WorldWideScience

Sample records for hybrid ultra-thin films

  1. Function and application of ultra thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sasabe, Hiroyuki

    1988-02-01

    A film 10-100mm thick which is strong dynamically to some extent and has possibility to manifest fuctions of high degree different from the nature extrapolated from the normal thin film is called an ultra thin film. As an example of its concrete application, there is an electro-luminescence element which is made by laminating 5 layers of LB films of poly-L-phenylalanine on a n-GaP and has vapor-deposited gold electrodes. When voltage of 5V is imposed to it, light emission of 565nm can be observed and the emission efficiency of 2% is obtained. Besides, it has an excellent stability through the lapse of time. There is also a junction element and the ion concentration injected into macromolecule films of this element has a Gaussian distribution from the surface towards the direction of depth. Accordingly, the most active domain in terms of semiconductor as the result of doping is the location in the neighborhood of the peak. Furthermore, a photo memory is also proposed. It is applied to the artificial hemoglobine which is made of LB films, suggesting the feasibility of creating the artificial protein capable of functioning in the conditions in which the natural protein is unable to function. (5 figs, 1 tab, 7 refs)

  2. Nanocoatings and ultra-thin films technologies and applications

    CERN Document Server

    Tiginyanu, Ion

    2011-01-01

    Gives a comprehensive account of the developments of nanocoatings and ultra-thin films. This book covers the fundamentals, processes of deposition and characterisation of nanocoatings, as well as the applications. It is suitable for the glass and glazing, automotive, electronics, aerospace, construction and biomedical industries in particular.$bCoatings are used for a wide range of applications, from anti-fogging coatings for glass through to corrosion control in the aerospace and automotive industries. Nanocoatings and ultra-thin films provides an up-to-date review of the fundamentals, processes of deposition, characterisation and applications of nanocoatings. Part one covers technologies used in the creation and analysis of thin films, including chapters on current and advanced coating technologies in industry, nanostructured thin films from amphiphilic molecules, chemical and physical vapour deposition methods and methods for analysing nanocoatings and ultra-thin films. Part two focuses on the applications...

  3. Ultra-thin zirconia films on Zr-alloys

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Joong Il Jake; Mayr-Schmoelzer, Wernfried; Mittendorfer, Florian; Redinger, Josef; Diebold, Ulrike; Schmid, Michael [Institute of Applied Physics, Vienna University of Technology (Austria); Li, Hao; Rupprechter, Guenther [Institute of Materials Chemistry, Vienna University of Technology (Austria)

    2014-07-01

    Zirconia ultra-thin films have been prepared by oxidation of Pt{sub 3}Zr(0001) and showed a structure equivalent to (111) of cubic zirconia. Following previous work, we have prepared ultra-thin zirconia by oxidation of a different alloy, Pd{sub 3}Zr(0001), which resulted in a similar structure with a slightly different lattice parameter, 351.2 ±0.4 pm. Unlike the oxide on Pt{sub 3}Zr, where Zr of the oxide binds to Pt in the substrate, here the oxide binds to substrate Zr via oxygen. This causes stronger distortion of the oxide structure, i.e. a stronger buckling of Zr in the oxide. After additional oxidation of ZrO{sub 2}/Pt{sub 3}Zr, a different ultra-thin zirconia phase is observed. A preliminary structure model for this film is based on (113)-oriented cubic zirconia. 3D oxide clusters are also present after growing ultra-thin zirconia films. They occur at the step edges, and the density is higher on Pd{sub 3}Zr. These clusters also appear on terraces after additional oxidation. XPS reveals different core level shifts of the oxide films, bulk, and oxide clusters.

  4. Resistive switching of organic–inorganic hybrid devices of conductive polymer and permeable ultra-thin SiO2 films

    Science.gov (United States)

    Yamamoto, Shunsuke; Kitanaka, Takahisa; Miyashita, Tokuji; Mitsuishi, Masaya

    2018-06-01

    We propose a resistive switching device composed of conductive polymer (PEDOT:PSS) and SiO2 ultra-thin films. The SiO2 film was fabricated from silsesquioxane polymer nanosheets as a resistive switching layer. Devices with metal (Ag or Au)∣SiO2∣PEDOT:PSS architecture show good resistive switching performance with set–reset voltages as low as several hundred millivolts. The device properties and the working mechanism were investigated by varying the electrode material, surrounding atmosphere, and SiO2 film thickness. Results show that resistive switching is based on water and ion migration at the PEDOT:PSS∣SiO2 interface.

  5. Optical properties of vacuum deposited polyaniline ultra-thin film

    International Nuclear Information System (INIS)

    Wahab, M. R. A.; Din, M.; Yunus, W. M. M.; Hasan, Z. A.; Kasim, A.

    2005-01-01

    Full text: Ultra-thin films of emeraldine base (EB) and emeraldine salt (ES) form of polyaniline (PANi) were prepared using electron-gun vacuum deposition. Thickness range studied was between 100AA and 450AA. Dielectric permittivity of the films determined from Kretchmann Configuration Surface Plasmon Resonance (SPR) angles-scanning set-up show shifts and narrowing of the SPR dip. Absorbance spectra of S-polarized and P-polarized light show the aging effect on orientation of the film. The effect of aging on its conductivity and photoluminescence is also correlated to the surface morphology

  6. Study of neural cells on organic semiconductor ultra thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bystrenova, Eva; Tonazzini, Ilaria; Stoliar, Pablo; Greco, Pierpaolo; Lazar, Adina; Dutta, Soumya; Dionigi, Chiara; Cacace, Marcello; Biscarini, Fabio [ISMN-CNR, Bologna (Italy); Jelitai, Marta; Madarasz, Emilia [IEM- HAS, Budapest (Hungary); Huth, Martin; Nickel, Bert [LMU, Munich (Germany); Martini, Claudia [Dept. PNPB, Univ. of Pisa (Italy)

    2008-07-01

    Many technological advances are currently being developed for nano-fabrication, offering the ability to create and control patterns of soft materials. We report the deposition of cells on organic semiconductor ultra-thin films. This is a first step towards the development of active bio/non bio systems for electrical transduction. Thin films of pentacene, whose thickness was systematically varied, were grown by high vacuum sublimation. We report adhesion, growth, and differentiation of human astroglial cells and mouse neural stem cells on an organic semiconductor. Viability of astroglial cells in time was measured as a function of the roughness and the characteristic morphology of ultra thin organic film, as well as the features of the patterned molecules. Optical fluorescence microscope coupled to atomic force microscope was used to monitor the presence, density and shape of deposited cells. Neural stem cells remain viable, differentiate by retinoic acid and form dense neuronal networks. We have shown the possibility to integrate living neural cells on organic semiconductor thin films.

  7. Ultra-thin films for plasmonics: a technology overview

    DEFF Research Database (Denmark)

    Malureanu, Radu; Lavrinenko, Andrei

    2015-01-01

    Ultra-thin films with low surface roughness that support surface plasmon-polaritons in the infra-red and visible ranges are needed in order to improve the performance of devices based on the manipulation of plasmon propagation. Increasing amount of efforts is made in order not only to improve...... the quality of the deposited layers but also to diminish their thickness and to find new materials that could be used in this field. In this review, we consider various thin films used in the field of plasmonics and metamaterials in the visible and IR range. We focus our presentation on technological issues...... of their deposition and reported characterization of film plasmonic performance....

  8. The strength limits of ultra-thin copper films

    Energy Technology Data Exchange (ETDEWEB)

    Wiederhirn, Guillaume

    2007-07-02

    Elucidating size effects in ultra-thin films is essential to ensure the performance and reliability of MEMS and electronic devices. In this dissertation, the influence of a capping layer on the mechanical behavior of copper (Cu) films was analyzed. Passivation is expected to shut down surface diffusion and thus to alter the contributions of dislocation- and diffusion-based plasticity in thin films. Experiments were carried out on 25 nm to 2 {mu}m thick Cu films magnetron-sputtered onto amorphous-silicon nitride coated silicon (111) substrates. These films were capped with 10 nm of aluminum oxide or silicon nitride passivation without breaking vacuum either directly after Cu deposition or after a 500 C anneal. The evolution of thermal stresses in these films was investigated mainly by the substrate curvature method between -160 C and 500 C. Negligible differences were detected for the silicon nitride vs. the aluminum oxide passivated Cu films. The processing parameters associated with the passivation deposition also had no noticeable effect on the stress-temperature behavior of the Cu. However, the thermomechanical behavior of passivated Cu films strongly depended on the Cu film thickness. For films in the micrometer range, the influence of the passivation layer was not significant, which suggests that the Cu deformed mainly by dislocation plasticity. However, diffusional creep plays an increasing role with decreasing film thickness since it becomes increasingly difficult to nucleate dislocations in smaller grains. Size effects were investigated by plotting the stress at room temperature after thermal cycling as a function of the inverse film thickness. Between 2 {mu}m and 200 nm, the room temperature stress was inversely proportional to the film thickness. The passivation exerted a strong effect on Cu films thinner than 100 nm by effectively shutting down surface diffusion mechanisms. Since dislocation processes were also shut off in these ultra-thin films, they

  9. Fabrication of Ultra-thin Color Films with Highly Absorbing Media Using Oblique Angle Deposition.

    Science.gov (United States)

    Yoo, Young Jin; Lee, Gil Ju; Jang, Kyung-In; Song, Young Min

    2017-08-29

    Ultra-thin film structures have been studied extensively for use as optical coatings, but performance and fabrication challenges remain.  We present an advanced method for fabricating ultra-thin color films with improved characteristics. The proposed process addresses several fabrication issues, including large area processing. Specifically, the protocol describes a process for fabricating ultra-thin color films using an electron beam evaporator for oblique angle deposition of germanium (Ge) and gold (Au) on silicon (Si) substrates.  Film porosity produced by the oblique angle deposition induces color changes in the ultra-thin film. The degree of color change depends on factors such as deposition angle and film thickness. Fabricated samples of the ultra-thin color films showed improved color tunability and color purity. In addition, the measured reflectance of the fabricated samples was converted into chromatic values and analyzed in terms of color. Our ultra-thin film fabricating method is expected to be used for various ultra-thin film applications such as flexible color electrodes, thin film solar cells, and optical filters. Also, the process developed here for analyzing the color of the fabricated samples is broadly useful for studying various color structures.

  10. Growth of ultra-thin Ag films on Ni(111)

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Axel; Flege, Jan Ingo; Falta, Jens [Institute of Solid State Physics, University of Bremen, 28359 Bremen (Germany); Senanayake, Sanjaya [Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Alamgir, Faisal [Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States)

    2009-07-01

    The physical and chemical properties of ultra-thin metal films on metallic substrates strongly depend on their morphology and the structure of the buried interface. Hence, detailed knowledge of the growth mechanisms is essential for the creation of new functional materials with novel characteristics. In this contribution, we present a comprehensive structural study of the growth and properties of epitaxial Ag films on Ni(111) by in-situ low energy electron microscopy (LEEM). For lower temperatures, the growth of the Ag film proceeds in a Stranski-Krastanov mode after completion of the wetting layer, while for higher temperatures layer-by-layer growth is observed. Quantitative information about the film structure were obtained by analyzing the intensity-voltage (I-V) dependence of the local electron reflectivity (IV-LEEM). The corresponding I(V) spectra showed intensity oscillations depending on local thickness of the Ag film due to the quantum size effect (QSE). Modeling of the I(V) spectra was performed both within the framework of a one-dimensional Kronig-Penney model and multiple scattering IV-LEED calculations. The results of both approaches concerning the variation of the layer spacings and interface characteristics for different temperatures and film thicknesses will be discussed.

  11. Spectroelectrochemical properties of ultra-thin indium tin oxide films under electric potential modulation

    Energy Technology Data Exchange (ETDEWEB)

    Han, Xue, E-mail: x0han004@louisville.edu; Mendes, Sergio B., E-mail: sbmend01@louisville.edu

    2016-03-31

    In this work, the spectroscopic properties of ultra-thin ITO films are characterized under an applied electric potential modulation. To detect minute spectroscopic features, the ultra-thin ITO film was coated over an extremely sensitive single-mode integrated optical waveguide, which provided a long pathlength with more than adequate sensitivity for optical interrogation of the ultra-thin film. Experimental configurations with broadband light and several laser lines at different modulation schemes of an applied electric potential were utilized to elucidate the nature of intrinsic changes. The imaginary component of the refractive index (absorption coefficient) of the ultra-thin ITO film is unequivocally shown to have a dependence on the applied potential and the profile of this dependence changes substantially even for wavelengths inside a small spectral window (500–600 nm). The characterization technique and the data reported here can be crucial to several applications of the ITO material as a transparent conductive electrode, as for example in spectroelectrochemical investigations of surface-confined redox species. - Highlights: • Optical waveguides are applied for spectroscopic investigations of ultra-thin films. • Ultra-thin ITO films in aqueous environment are studied under potential modulation. • Unique spectroscopic features of ultra-thin ITO films are unambiguously observed.

  12. Film-thickness dependence of structure formation in ultra-thin polymer blend films

    CERN Document Server

    Gutmann, J S; Stamm, M

    2002-01-01

    We investigated the film-thickness dependence of structure formation in ultra-thin polymer blend films prepared from solution. As a model system we used binary blends of statistical poly(styrene-co-p-bromostyrene) copolymers of different degrees of bromination. Ultra-thin-film samples differing in miscibility and film thickness were prepared via spin coating of common toluene solutions onto silicon (100) substrates. The resulting morphologies were investigated with scanning force microscopy, reflectometry and grazing-incidence scattering techniques using both X-rays and neutrons in order to obtain a picture of the sample structure at and below the sample surface. (orig.)

  13. Ultra-thin silicon/electro-optic polymer hybrid waveguide modulators

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Feng; Spring, Andrew M. [Institute for Materials Chemistry and Engineering, Kyushu University, 6-1 Kasuga-koen Kasuga, Fukuoka 816-8580 (Japan); Sato, Hiromu [Department of Molecular and Material Sciences, Kyushu University, 6-1 Kasuga-koen Kasuga, Fukuoka 816-8580 (Japan); Maeda, Daisuke; Ozawa, Masa-aki; Odoi, Keisuke [Nissan Chemical Industries, Ltd., 2-10-1 Tuboi Nishi, Funabashi, Chiba 274-8507 (Japan); Aoki, Isao; Otomo, Akira [National Institute of Information and Communications Technology, 588-2 Iwaoka, Nishi-ku, Kobe 651-2492 (Japan); Yokoyama, Shiyoshi, E-mail: s-yokoyama@cm.kyushu-u.ac.jp [Institute for Materials Chemistry and Engineering, Kyushu University, 6-1 Kasuga-koen Kasuga, Fukuoka 816-8580 (Japan); Department of Molecular and Material Sciences, Kyushu University, 6-1 Kasuga-koen Kasuga, Fukuoka 816-8580 (Japan)

    2015-09-21

    Ultra-thin silicon and electro-optic (EO) polymer hybrid waveguide modulators have been designed and fabricated. The waveguide consists of a silicon core with a thickness of 30 nm and a width of 2 μm. The cladding is an EO polymer. Optical mode calculation reveals that 55% of the optical field around the silicon extends into the EO polymer in the TE mode. A Mach-Zehnder interferometer (MZI) modulator was prepared using common coplanar electrodes. The measured half-wave voltage of the MZI with 7 μm spacing and 1.3 cm long electrodes is 4.6 V at 1550 nm. The evaluated EO coefficient is 70 pm/V, which is comparable to that of the bulk EO polymer film. Using ultra-thin silicon is beneficial in order to reduce the side-wall scattering loss, yielding a propagation loss of 4.0 dB/cm. We also investigated a mode converter which couples light from the hybrid EO waveguide into a strip silicon waveguide. The calculation indicates that the coupling loss between these two devices is small enough to exploit the potential fusion of a hybrid EO polymer modulator together with a silicon micro-photonics device.

  14. Epitaxial stabilization of ultra thin films of electron doped manganites

    Energy Technology Data Exchange (ETDEWEB)

    Middey, S., E-mail: smiddey@uark.edu; Kareev, M.; Meyers, D.; Liu, X.; Cao, Y.; Tripathi, S.; Chakhalian, J. [Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701 (United States); Yazici, D.; Maple, M. B. [Department of Physics, University of California, San Diego, La Jolla, California 92093 (United States); Ryan, P. J.; Freeland, J. W. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

    2014-05-19

    Ultra-thin films of the electron doped manganite La{sub 0.8}Ce{sub 0.2}MnO{sub 3} were grown in a layer-by-layer growth mode on SrTiO{sub 3} (001) substrates by pulsed laser interval deposition. High structural quality and surface morphology were confirmed by a combination of synchrotron based x-ray diffraction and atomic force microscopy. Resonant X-ray absorption spectroscopy measurements confirm the presence of Ce{sup 4+} and Mn{sup 2+} ions. In addition, the electron doping signature was corroborated by Hall effect measurements. All grown films show a ferromagnetic ground state as revealed by both dc magnetization and x-ray magnetic circular dichroism measurements and remain insulating contrary to earlier reports of a metal-insulator transition. Our results hint at the possibility of electron-hole asymmetry in the colossal magnetoresistive manganite phase diagram akin to the high-T{sub c} cuprates.

  15. Mesoporous polyaniline film on ultra-thin graphene sheets for high performance supercapacitors

    Science.gov (United States)

    Wang, Qian; Yan, Jun; Fan, Zhuangjun; Wei, Tong; Zhang, Milin; Jing, Xiaoyan

    2014-02-01

    A facile approach has been developed to fabricate mesoporous PANI film on ultra-thin graphene nanosheet (G-mPANI) hybrid by in situ polymerization using graphene-mesoporous silica composite as template. Due to its mesoporous structure, over-all conductive network, G-mPANI electrode displays a specific capacitance of 749 F g-1 at 0.5 A g-1 with excellent rate capability (remains 73% even at 5.0 A g-1), much higher than that of pristine PANI electrode (315 F g-1 at 0.5 A g-1, 39% retention at 5.0 A g-1) in 1 mol L-1 H2SO4 aqueous solution. More interestingly, the G-mPANI hybrid can maintain 88% of its initial capacitance compared to 45% for pristine PANI after 1000 cycles, suggesting a superior electrochemical cyclic stability.

  16. Colored ultra-thin hybrid photovoltaics with high quantum efficiency for decorative PV applications (Presentation Recording)

    Science.gov (United States)

    Guo, L. Jay

    2015-10-01

    This talk will describe an approach to create architecturally compatible and decorative thin-film-based hybrid photovoltaics [1]. Most current solar panels are fabricated via complex processes using expensive semiconductor materials, and they are rigid and heavy with a dull, black appearance. As a result of their non-aesthetic appearance and weight, they are primarily installed on rooftops to minimize their negative impact on building appearance. Recently we introduced dual-function solar cells based on ultra-thin dopant-free amorphous silicon embedded in an optical cavity that not only efficiently extract the photogenerated carriers but also display distinctive colors with the desired angle-insensitive appearances [1,2]. The angle-insensitive behavior is the result of an interesting phase cancellation effect in the optical cavity with respect to angle of light propagation [3]. In order to produce the desired optical effect, the semiconductor layer should be ultra-thin and the traditional doped layers need to be eliminated. We adopted the approach of employing charge transport/blocking layers used in organic solar cells to meet this demand. We showed that the ultra-thin (6 to 31 nm) undoped amorphous silicon/organic hybrid solar cell can transmit desired wavelength of light and that most of the absorbed photons in the undoped a-Si layer contributed to the extracted electric charges. This is because the a-Si layer thickness is smaller than the charge diffusion length, therefore the electron-hole recombination is strongly suppressed in such ultra-thin layer. Reflective colored PVs can be made in a similar fashion. Light-energy-harvesting colored signage was demonstrated. Furthermore, a cascaded photovoltaics scheme based on tunable spectrum splitting can be employed to increase power efficiency by absorbing a broader band of light energy. Our work provides a guideline for optimizing a photoactive layer thickness in high efficiency hybrid PV design, which can be

  17. COVALENTLY ATTACHED MULTILAYER ULTRA-THIN FILMS FROM DIAZORESIN AND CALIXARENES

    Institute of Scientific and Technical Information of China (English)

    Zhao-hui Yang; Wei-xiao Cao

    2003-01-01

    A kind of photosensitive ultra-thin film was fabricated from diazoresin (DR) and various calixarenes by using the self-assembly technique. Under UV irradiation both the ionic- and hydrogen bonds between the layers of the film will convert into covalent bonds. As a result, the stability of the film toward polar solvents increases dramatically.

  18. Ultra-thin film encapsulation processes for micro-electro-mechanical devices and systems

    International Nuclear Information System (INIS)

    Stoldt, Conrad R; Bright, Victor M

    2006-01-01

    A range of physical properties can be achieved in micro-electro-mechanical systems (MEMS) through their encapsulation with solid-state, ultra-thin coatings. This paper reviews the application of single source chemical vapour deposition and atomic layer deposition (ALD) in the growth of submicron films on polycrystalline silicon microstructures for the improvement of microscale reliability and performance. In particular, microstructure encapsulation with silicon carbide, tungsten, alumina and alumina-zinc oxide alloy ultra-thin films is highlighted, and the mechanical, electrical, tribological and chemical impact of these overlayers is detailed. The potential use of solid-state, ultra-thin coatings in commercial microsystems is explored using radio frequency MEMS as a case study for the ALD alloy alumina-zinc oxide thin film. (topical review)

  19. On the difference between optically and electrically determined resistivity of ultra-thin titanium nitride films

    NARCIS (Netherlands)

    Van Hao, B.; Kovalgin, Alexeij Y.; Wolters, Robertus A.M.

    2013-01-01

    This work reports on the determination and comparison of the resistivity of ultra-thin atomic layer deposited titanium nitride films in the thickness range 0.65–20 nm using spectroscopic ellipsometry and electrical test structures. We found that for films thicker than 4 nm, the resistivity values

  20. Nanometric thin film membranes manufactured on square meter scale: ultra-thin films for CO 2 capture

    KAUST Repository

    Yave, Wilfredo; Car, Anja; Wind, Jan; Peinemann, Klaus Viktor

    2010-01-01

    Miniaturization and manipulation of materials at nanometer scale are key challenges in nanoscience and nanotechnology. In membrane science and technology, the fabrication of ultra-thin polymer films (defect-free) on square meter scale with uniform

  1. How Do Organic Vapors Swell Ultra-Thin PIM-1 Films?

    KAUST Repository

    Ogieglo, Wojciech; Rahimi, Khosrow; Rauer, Sebastian Bernhard; Ghanem, Bader; Ma, Xiao-Hua; Pinnau, Ingo; Wessling, Matthias

    2017-01-01

    Dynamic sorption of ethanol and toluene vapor into ultra-thin supported PIM-1 films down to 6 nm are studied with a combination of in-situ spectroscopic ellipsometry and in-situ X-ray reflectivity. Both ethanol and toluene significantly swell

  2. Reliability assessment of ultra-thin HfO2 films deposited on silicon wafer

    International Nuclear Information System (INIS)

    Fu, Wei-En; Chang, Chia-Wei; Chang, Yong-Qing; Yao, Chih-Kai; Liao, Jiunn-Der

    2012-01-01

    Highlights: ► Nano-mechanical properties on annealed ultra-thin HfO 2 film are studied. ► By AFM analysis, hardness of the crystallized HfO 2 film significantly increases. ► By nano-indention, the film hardness increases with less contact stiffness. ► Quality assessment on the annealed ultra-thin films can thus be achieved. - Abstract: Ultra-thin hafnium dioxide (HfO 2 ) is used to replace silicon dioxide to meet the required transistor feature size in advanced semiconductor industry. The process integration compatibility and long-term reliability for the transistors depend on the mechanical performance of ultra-thin HfO 2 films. The criteria of reliability including wear resistance, thermal fatigue, and stress-driven failure rely on film adhesion significantly. The adhesion and variations in mechanical properties induced by thermal annealing of the ultra-thin HfO 2 films deposited on silicon wafers (HfO 2 /SiO 2 /Si) are not fully understood. In this work, the mechanical properties of an atomic layer deposited HfO 2 (nominal thickness ≈10 nm) on a silicon wafer were characterized by the diamond-coated tip of an atomic force microscope and compared with those of annealed samples. The results indicate that the annealing process leads to the formation of crystallized HfO 2 phases for the atomic layer deposited HfO 2 . The HfSi x O y complex formed at the interface between HfO 2 and SiO 2 /Si, where the thermal diffusion of Hf, Si, and O atoms occurred. The annealing process increases the surface hardness of crystallized HfO 2 film and therefore the resistance to nano-scratches. In addition, the annealing process significantly decreases the harmonic contact stiffness (or thereafter eliminate the stress at the interface) and increases the nano-hardness, as measured by vertically sensitive nano-indentation. Quality assessments on as-deposited and annealed HfO 2 films can be thereafter used to estimate the mechanical properties and adhesion of ultra-thin HfO 2

  3. Reliability assessment of ultra-thin HfO{sub 2} films deposited on silicon wafer

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Wei-En [Center for Measurement Standards, Industrial Technology Research Institute, Room 216, Building 8, 321 Kuang Fu Road Sec. 2, Hsinchu, Taiwan (China); Chang, Chia-Wei [Department of Materials Science and Engineering, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Chang, Yong-Qing [Center for Measurement Standards, Industrial Technology Research Institute, Room 216, Building 8, 321 Kuang Fu Road Sec. 2, Hsinchu, Taiwan (China); Yao, Chih-Kai [Department of Materials Science and Engineering, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Liao, Jiunn-Der, E-mail: jdliao@mail.ncku.edu.tw [Department of Materials Science and Engineering, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China)

    2012-09-01

    Highlights: Black-Right-Pointing-Pointer Nano-mechanical properties on annealed ultra-thin HfO{sub 2} film are studied. Black-Right-Pointing-Pointer By AFM analysis, hardness of the crystallized HfO{sub 2} film significantly increases. Black-Right-Pointing-Pointer By nano-indention, the film hardness increases with less contact stiffness. Black-Right-Pointing-Pointer Quality assessment on the annealed ultra-thin films can thus be achieved. - Abstract: Ultra-thin hafnium dioxide (HfO{sub 2}) is used to replace silicon dioxide to meet the required transistor feature size in advanced semiconductor industry. The process integration compatibility and long-term reliability for the transistors depend on the mechanical performance of ultra-thin HfO{sub 2} films. The criteria of reliability including wear resistance, thermal fatigue, and stress-driven failure rely on film adhesion significantly. The adhesion and variations in mechanical properties induced by thermal annealing of the ultra-thin HfO{sub 2} films deposited on silicon wafers (HfO{sub 2}/SiO{sub 2}/Si) are not fully understood. In this work, the mechanical properties of an atomic layer deposited HfO{sub 2} (nominal thickness Almost-Equal-To 10 nm) on a silicon wafer were characterized by the diamond-coated tip of an atomic force microscope and compared with those of annealed samples. The results indicate that the annealing process leads to the formation of crystallized HfO{sub 2} phases for the atomic layer deposited HfO{sub 2}. The HfSi{sub x}O{sub y} complex formed at the interface between HfO{sub 2} and SiO{sub 2}/Si, where the thermal diffusion of Hf, Si, and O atoms occurred. The annealing process increases the surface hardness of crystallized HfO{sub 2} film and therefore the resistance to nano-scratches. In addition, the annealing process significantly decreases the harmonic contact stiffness (or thereafter eliminate the stress at the interface) and increases the nano-hardness, as measured by vertically

  4. Field emission mechanism from a single-layer ultra-thin semiconductor film cathode

    International Nuclear Information System (INIS)

    Duan Zhiqiang; Wang Ruzhi; Yuan Ruiyang; Yang Wei; Wang Bo; Yan Hui

    2007-01-01

    Field emission (FE) from a single-layer ultra-thin semiconductor film cathode (SUSC) on a metal substrate has been investigated theoretically. The self-consistent quantum FE model is developed by synthetically considering the energy band bending and electron scattering. As a typical example, we calculate the FE properties of ultra-thin AlN film with an adjustable film thickness from 1 to 10 nm. The calculated results show that the FE characteristic is evidently modulated by varying the film thickness, and there is an optimum thickness of about 3 nm. Furthermore, a four-step FE mechanism is suggested such that the distinct FE current of a SUSC is rooted in the thickness sensitivity of its quantum structure, and the optimum FE properties of the SUSC should be attributed to the change in the effective potential combined with the attenuation of electron scattering

  5. Determining surface coverage of ultra-thin gold films from X-ray reflectivity measurements

    International Nuclear Information System (INIS)

    Kossoy, A.; Simakov, D.; Olafsson, S.; Leosson, K.

    2013-01-01

    The paper describes usage of X-ray reflectivity for characterization of surface coverage (i.e. film continuity) of ultra-thin gold films which are widely studied for optical, plasmonic and electronic applications. The demonstrated method is very sensitive and can be applied for layers below 1 nm. It has several advantages over other techniques which are often employed in characterization of ultra-thin metal films, such as optical absorption, Atomic Force Microscopy, Transmission Electron Microscopy or Scanning Electron Microscopy. In contrast to those techniques our method does not require specialized sample preparation and measurement process is insensitive to electrostatic charge and/or presence of surface absorbed water. We validate our results with image processing of Scanning Electron Microscopy images. To ensure precise quantitative analysis of the images we developed a generic local thresholding algorithm which allowed us to treat series of images with various values of surface coverage with similar image processing parameters. - Highlights: • Surface coverage/continuity of ultra-thin Au films (up to 7 nm) was determined. • Results from X-ray reflectivity were verified by scanning electron microscopy. • We developed local thresholding algorithm to treat non-homogeneous image contrast

  6. Structural studies on Langmuir-Blodgett ultra-thin films on tin (IV) stearate using X-ray diffraction technique

    International Nuclear Information System (INIS)

    Mohamad Deraman; Muhamad Mat Salleh; Mohd Ali Sulaiman; Mohd Ali Sufi

    1991-01-01

    X-ray diffraction measurements were carried out on Langmuir-Blodgett (LB) ultra-thin films of tin (IV) stearate for different numbers of layers. The structural information such as interplanar spacing, unit cells spacing, molecular length and orientation of molecular chains were obtained from the diffraction data. This information is discussed and compared with that previously published for LB ultra-thin films of manganese stearate and cadmium stearate

  7. Management of light absorption in extraordinary optical transmission based ultra-thin-film tandem solar cells

    International Nuclear Information System (INIS)

    Mashooq, Kishwar; Talukder, Muhammad Anisuzzaman

    2016-01-01

    Although ultra-thin-film solar cells can be attractive in reducing the cost, they suffer from low absorption as the thickness of the active layer is usually much smaller than the wavelength of incident light. Different nano-photonic techniques, including plasmonic structures, are being explored to increase the light absorption in ultra-thin-film solar cells. More than one layer of active materials with different energy bandgaps can be used in tandem to increase the light absorption as well. However, due to different amount of light absorption in different active layers, photo-generated currents in different active layers will not be the same. The current mismatch between the tandem layers makes them ineffective in increasing the efficiency. In this work, we investigate the light absorption properties of tandem solar cells with two ultra-thin active layers working as two subcells and a metal layer with periodically perforated holes in-between the two subcells. While the metal layer helps to overcome the current mismatch, the periodic holes increase the absorption of incident light by helping extraordinary optical transmission of the incident light from the top to the bottom subcell, and by coupling the incident light to plasmonic and photonic modes within ultra-thin active layers. We extensively study the effects of the geometry of holes in the intermediate metal layer on the light absorption properties of tandem solar cells with ultra-thin active layers. We also study how different metals in the intermediate layer affect the light absorption; how the geometry of holes in the intermediate layer affects the absorption when the active layer materials are changed; and how the intermediate metal layer affects the collection of photo-generated electron-hole pairs at the terminals. We find that in a solar cell with 6,6-phenyl C61-butyric acid methyl ester top subcell and copper indium gallium selenide bottom subcell, if the periodic holes in the metal layer are square or

  8. Management of light absorption in extraordinary optical transmission based ultra-thin-film tandem solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Mashooq, Kishwar; Talukder, Muhammad Anisuzzaman, E-mail: anis@eee.buet.ac.bd [Department of Electrical and Electronic Engineering, Bangladesh University of Engineering and Technology, Dhaka 1205 (Bangladesh)

    2016-05-21

    Although ultra-thin-film solar cells can be attractive in reducing the cost, they suffer from low absorption as the thickness of the active layer is usually much smaller than the wavelength of incident light. Different nano-photonic techniques, including plasmonic structures, are being explored to increase the light absorption in ultra-thin-film solar cells. More than one layer of active materials with different energy bandgaps can be used in tandem to increase the light absorption as well. However, due to different amount of light absorption in different active layers, photo-generated currents in different active layers will not be the same. The current mismatch between the tandem layers makes them ineffective in increasing the efficiency. In this work, we investigate the light absorption properties of tandem solar cells with two ultra-thin active layers working as two subcells and a metal layer with periodically perforated holes in-between the two subcells. While the metal layer helps to overcome the current mismatch, the periodic holes increase the absorption of incident light by helping extraordinary optical transmission of the incident light from the top to the bottom subcell, and by coupling the incident light to plasmonic and photonic modes within ultra-thin active layers. We extensively study the effects of the geometry of holes in the intermediate metal layer on the light absorption properties of tandem solar cells with ultra-thin active layers. We also study how different metals in the intermediate layer affect the light absorption; how the geometry of holes in the intermediate layer affects the absorption when the active layer materials are changed; and how the intermediate metal layer affects the collection of photo-generated electron-hole pairs at the terminals. We find that in a solar cell with 6,6-phenyl C61-butyric acid methyl ester top subcell and copper indium gallium selenide bottom subcell, if the periodic holes in the metal layer are square or

  9. Low-temperature transport in ultra-thin tungsten films

    Energy Technology Data Exchange (ETDEWEB)

    Chiatti, Olivio [Neue Materialien, Institut fuer Physik, Humboldt-Univ. Berlin (Germany); London Centre for Nanotechnology, University College London (United Kingdom); Nash, Christopher; Warburton, Paul [London Centre for Nanotechnology, University College London (United Kingdom)

    2012-07-01

    Tungsten-containing films, fabricated by focused-ion-beam-induced chemical vapour deposition, are known to have an enhanced superconducting transition temperature compared to bulk tungsten, and have been investigated previously for film thickness down to 25 nm. In this work, by using ion-beam doses below 50 pC/{mu}m{sup 2} on a substrate of amorphous silicon, we have grown continuous films with thickness below 20 nm. The electron transport properties were investigated at temperatures down to 350 mK and in magnetic fields up to 3 T, parallel and perpendicular to the films. The films in this work are closer to the limit of two-dimensional systems and are superconducting at low temperatures. Magnetoresistance measurements yield upper critical fields of the order of 1 T, and the resulting coherence length is smaller than the film thickness.

  10. Surface Acoustic Wave Monitor for Deposition and Analysis of Ultra-Thin Films

    Science.gov (United States)

    Hines, Jacqueline H. (Inventor)

    2015-01-01

    A surface acoustic wave (SAW) based thin film deposition monitor device and system for monitoring the deposition of ultra-thin films and nanomaterials and the analysis thereof is characterized by acoustic wave device embodiments that include differential delay line device designs, and which can optionally have integral reference devices fabricated on the same substrate as the sensing device, or on a separate device in thermal contact with the film monitoring/analysis device, in order to provide inherently temperature compensated measurements. These deposition monitor and analysis devices can include inherent temperature compensation, higher sensitivity to surface interactions than quartz crystal microbalance (QCM) devices, and the ability to operate at extreme temperatures.

  11. Non-ohmic transport behavior in ultra-thin gold films

    International Nuclear Information System (INIS)

    Alkhatib, A.; Souier, T.; Chiesa, M.

    2011-01-01

    Highlights: → C-AFM study on ultra-thin gold films. → Connection between ultra-thin film morphology and lateral electrical transport. → Transition between ohmic and non-ohmic behavior. → Electrical transition correlation to the film structure continuity. → Direct and indirect tunneling regimes related to discontinuous structures. - Abstract: Structure and local lateral electrical properties of Au films of thicknesses ranging from 10 to 140 nm are studied using conductive atomic force microscopy. Comparison of current maps taken at different thicknesses reveals surprising highly resistive regions (10 10 -10 11 Ω), the density of which increases strongly at lower thickness. The high resistivity is shown to be directly related to discontinuities in the metal sheet. Local I-V curves are acquired to show the nature of electrical behavior relative to thickness. Results show that in Au films of higher thickness the electrical behavior is ohmic, while it is non-ohmic in highly discontinuous films of lower thickness, with the transition happening between 34 and 39 nm. The non-ohmic behavior is explained with tunneling occurring between separated Au islands. The results explain the abrupt increase of electrical resistivity at lower thin film thicknesses.

  12. Dependence of the organic nonvolatile memory performance on the location of ultra-thin Ag film

    International Nuclear Information System (INIS)

    Jiao Bo; Wu Zhaoxin; He Qiang; Mao Guilin; Hou Xun; Tian Yuan

    2010-01-01

    We demonstrated organic nonvolatile memory devices based on 4,4',4''-tris[N-(3-methylphenyl)-N-phenylamino] triphenylamine (m-MTDATA) inserted by an ultra-thin Ag film. The memory devices with different locations of ultra-thin Ag film in m-MTDATA were investigated, and it was found that the location of the Ag film could affect the performance of the organic memory, such as ON/OFF ratio, retention time and cycling endurance. When the Ag film was located at the ITO/m-MTDATA interface, the largest ON/OFF ratio (about 10 5 ) could be achieved, but the cycling endurance was poor. When the Ag film was located in the middle region of the m-MTDATA layer, the ON/OFF ratios came down by about 10 3 , but better performance of cycling endurance was exhibited. When the Ag film was located close to the Al electrode, the ON/OFF ratios and the retention time of this device decreased sharply and the bistable phenomenon almost disappeared. Our works show a simple approach to improve the performance of organic memory by adjusting the location of the metal film.

  13. Electrical properties of single crystal Yttrium Iron Garnet ultra-thin films at high temperatures

    OpenAIRE

    Thiery, Nicolas; Naletov, Vladimir V.; Vila, Laurent; Marty, Alain; Brenac, Ariel; Jacquot, Jean-François; de Loubens, Grégoire; Viret, Michel; Anane, Abdelmadjid; Cros, Vincent; Youssef, Jamal Ben; Demidov, Vladislav E.; Demokritov, Sergej O.; Klein, Olivier

    2017-01-01

    We report a study on the electrical properties of 19 nm thick Yttrium Iron Garnet (YIG) films grown by liquid phase epitaxy. The electrical conductivity and Hall coefficient are measured in the high temperature range [300,400]~K using a Van der Pauw four-point probe technique. We find that the electrical resistivity decreases exponentially with increasing temperature following an activated behavior corresponding to a band-gap of $E_g\\approx 2$ eV, indicating that epitaxial YIG ultra-thin film...

  14. Mechanical properties of ultra thin metallic films revealed by synchrotron techniques

    Energy Technology Data Exchange (ETDEWEB)

    Gruber, Patric Alfons

    2007-07-20

    A prerequisite for the study of the scaling behavior of mechanical properties of ultra thin films is a suitable testing technique. Therefore synchrotron-based in situ testing techniques were developed and optimized in order to characterize the stress evolution in ultra thin metallic films on compliant polymer substrates during isothermal tensile tests. Experimental procedures for polycrystalline as well as single crystalline films were established. These techniques were used to systematically investigate the influence of microstructure, film thickness (20 to 1000 nm) and temperature (-150 to 200 C) on the mechanical properties. Passivated and unpassivated Au and Cu films as well as single crystalline Au films on polyimide substrates were tested. Special care was also dedicated to the microstructural characterization of the samples which was very important for the correct interpretation of the results of the mechanical tests. Down to a film thickness of about 100 to 200 nm the yield strength increased for all film systems (passivated and unpassivated) and microstructures (polycrystalline and singlecrystalline). The influence of different interfaces was smaller than expected. This could be explained by a dislocation source model based on the nucleation of perfect dislocations. For polycrystalline films the film thickness as well as the grain size distribution had to be considered. For smaller film thicknesses the increase in flow stress was weaker and the deformation behavior changed because the nucleation of perfect dislocations became unfavorable. Instead, the film materials used alternative mechanisms to relieve the high stresses. For regular and homogeneous deformation the total strain was accommodated by the nucleation and motion of partial dislocations. If the deformation was localized due to initial cracks in a brittle interlayer or local delamination, dislocation plasticity was not effective enough to relieve the stress concentration and the films showed

  15. Ultra thin hydro-films based on lactose-crosslinked fish gelatin for wound healing applications.

    Science.gov (United States)

    Etxabide, Alaitz; Vairo, Claudia; Santos-Vizcaino, Edorta; Guerrero, Pedro; Pedraz, Jose Luis; Igartua, Manoli; de la Caba, Koro; Hernandez, Rosa Maria

    2017-09-15

    This study focuses on the development and characterization of an ultra thin hydro-film based on lactose-mediated crosslinking of fish gelatin by Maillard reaction. Lactose results in the only efficient crosslinker able to produce resistant to handling hydro-films when compared to conventional crosslinkers such as glutaraldehyde or genipin (tested at 25 and 37°C in phosphate buffer saline solution (PBS)).The disappearance of the peak related to the N-containing groups (XPS) and the images obtained by SEM and AFM demonstrate the highly ordered nano-scaled structure of lactose-crosslinked gelatin, confirming the crosslinking efficiency. This dressing presents high hydrophilicity and mild occlusivity, as shown by the swelling curve (max swelling at 5min) and by the occlusion factor of 25.17±0.99%, respectively. It demonstrates high stability to hydrolysis or cell-mediated degradation. Moreover, ISO 10993-5:2009 biocompatibility assay results in undetectable cytotoxicity effects. Spreading, adhesion and proliferation assays confirm the excellent adaptability of the cells onto the hydro-film surface without invading the dressing. Finally, the hydro-film enables the controlled delivery of therapeutic factors, such as the epidermal growth factor (EGF). This study demonstrates that lactose-mediated crosslinking is able to produce ultra thin gelatin hydro-films with suitable properties for biomedical applications, such as wound healing. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Local variation of fragility and glass transition temperature of ultra-thin supported polymer films.

    Science.gov (United States)

    Hanakata, Paul Z; Douglas, Jack F; Starr, Francis W

    2012-12-28

    Despite extensive efforts, a definitive picture of the glass transition of ultra-thin polymer films has yet to emerge. The effect of film thickness h on the glass transition temperature T(g) has been widely examined, but this characterization does not account for the fragility of glass-formation, which quantifies how rapidly relaxation times vary with temperature T. Accordingly, we simulate supported polymer films of a bead-spring model and determine both T(g) and fragility, both as a function of h and film depth. We contrast changes in the relaxation dynamics with density ρ and demonstrate the limitations of the commonly invoked free-volume layer model. As opposed to bulk polymer materials, we find that the fragility and T(g) do not generally vary proportionately. Consequently, the determination of the fragility profile--both locally and for the film as a whole--is essential for the characterization of changes in film dynamics with confinement.

  17. Growth and hydrogenation of ultra-thin Mg films on Mo(111)

    DEFF Research Database (Denmark)

    Ostenfeld, Christopher Worsøe; Davies, Jonathan Conrad; Vegge, Tejs

    2005-01-01

    . Hydrogen cannot be adsorbed on magnesium films under UHV conditions. However, when evaporating Mg in a hydrogen background, a hydrogen overlayer is seen to adsorb at the Mg surface, due to the catalytic interaction with the Mo(1 1 1) substrate and subsequent spill-over. We show that two monolayers of Mg......The growth and hydrogenation of ultra-thin magnesium overlayers have been investigated on a Mo(1 1 1) single crystal substrate. For increasing magnesium coverages we observe intermediate stages in the TPD and LEISS profiles, which illustrate the transition from one monolayer to multilayer growth...

  18. Synchrotron-radiation XPS analysis of ultra-thin silane films: Specifying the organic silicon

    Energy Technology Data Exchange (ETDEWEB)

    Dietrich, Paul M., E-mail: paul.dietrich@yahoo.de [Bundesanstalt für Materialforschung und – prüfung (BAM), Unter den Eichen 87, 12205 Berlin (Germany); Glamsch, Stephan [Bundesanstalt für Materialforschung und – prüfung (BAM), Unter den Eichen 87, 12205 Berlin (Germany); Freie Universität Berlin, Institut für Chemie und Biochemie, Fabeckstr. 34/36, 14195 Berlin (Germany); Ehlert, Christopher [Bundesanstalt für Materialforschung und – prüfung (BAM), Unter den Eichen 87, 12205 Berlin (Germany); Institut für Chemie, Universität Potsdam, Karl-Liebknecht-Straße 24-25, 14476 Potsdam (Germany); Lippitz, Andreas [Bundesanstalt für Materialforschung und – prüfung (BAM), Unter den Eichen 87, 12205 Berlin (Germany); Kulak, Nora [Freie Universität Berlin, Institut für Chemie und Biochemie, Fabeckstr. 34/36, 14195 Berlin (Germany); Unger, Wolfgang E.S. [Bundesanstalt für Materialforschung und – prüfung (BAM), Unter den Eichen 87, 12205 Berlin (Germany)

    2016-02-15

    Graphical abstract: - Highlights: • A synchrotron-based XPS method to analyze ultra-thin silane films is presented. • Specification and quantification of organic next to inorganic silicon is demonstrated. • Non-destructive chemical depth profiles of the silane monolayers were obtained. - Abstract: The analysis of chemical and elemental in-depth variations in ultra-thin organic layers with thicknesses below 5 nm is very challenging. Energy- and angle-resolved XPS (ER/AR-XPS) opens up the possibility for non-destructive chemical ultra-shallow depth profiling of the outermost surface layer of ultra-thin organic films due to its exceptional surface sensitivity. For common organic materials a reliable chemical in-depth analysis with a lower limit of the XPS information depth z{sub 95} of about 1 nm can be performed. As a proof-of-principle example with relevance for industrial applications the ER/AR-XPS analysis of different organic monolayers made of amino- or benzamidosilane molecules on silicon oxide surfaces is presented. It is demonstrated how to use the Si 2p core-level region to non-destructively depth-profile the organic (silane monolayer) – inorganic (SiO{sub 2}/Si) interface and how to quantify Si species, ranging from elemental silicon over native silicon oxide to the silane itself. The main advantage of the applied ER/AR-XPS method is the improved specification of organic from inorganic silicon components in Si 2p core-level spectra with exceptional low uncertainties compared to conventional laboratory XPS.

  19. Operando SXRD of E-ALD deposited sulphides ultra-thin films: Crystallite strain and size

    Science.gov (United States)

    Giaccherini, Andrea; Russo, Francesca; Carlà, Francesco; Guerri, Annalisa; Picca, Rosaria Anna; Cioffi, Nicola; Cinotti, Serena; Montegrossi, Giordano; Passaponti, Maurizio; Di Benedetto, Francesco; Felici, Roberto; Innocenti, Massimo

    2018-02-01

    Electrochemical Atomic Layer Deposition (E-ALD), exploiting surface limited electrodeposition of atomic layers, can easily grow highly ordered ultra-thin films and 2D structures. Among other compounds CuxZnyS grown by means of E-ALD on Ag(111) has been found particularly suitable for the solar energy conversion due to its band gap (1.61 eV). However its growth seems to be characterized by a micrometric thread-like structure, probably overgrowing a smooth ultra-thin films. On this ground, a SXRD investigation has been performed, to address the open questions about the structure and the growth of CuxZnyS by means of E-ALD. The experiment shows a pseudo single crystal pattern as well as a powder pattern, confirming that part of the sample grows epitaxially on the Ag(111) substrate. The growth of the film was monitored by following the evolution of the Bragg peaks and Debye rings during the E-ALD steps. Breadth and profile analysis of the Bragg peaks lead to a qualitative interpretation of the growth mechanism. This study confirms that Zn lead to the growth of a strained Cu2S-like structure, while the growth of the thread-like structure is probably driven by the release of the stress from the epitaxial phase.

  20. Nanometric thin film membranes manufactured on square meter scale: ultra-thin films for CO 2 capture

    KAUST Repository

    Yave, Wilfredo

    2010-09-01

    Miniaturization and manipulation of materials at nanometer scale are key challenges in nanoscience and nanotechnology. In membrane science and technology, the fabrication of ultra-thin polymer films (defect-free) on square meter scale with uniform thickness (<100 nm) is crucial. By using a tailor-made polymer and by controlling the nanofabrication conditions, we developed and manufactured defect-free ultra-thin film membranes with unmatched carbon dioxide permeances, i.e. >5 m3 (STP) m-2 h -1 bar-1. The permeances are extremely high, because the membranes are made from a CO2 philic polymer material and they are only a few tens of nanometers thin. Thus, these thin film membranes have potential application in the treatment of large gas streams under low pressure like, e.g., carbon dioxide separation from flue gas. © 2010 IOP Publishing Ltd.

  1. Mixed-Penetrant Sorption in Ultra-Thin Films of Polymer of Intrinsic Microporosity PIM-1

    KAUST Repository

    Ogieglo, Wojciech; Furchner, Andreas; Ghanem, Bader; Ma, Xiao-Hua; Pinnau, Ingo; Wessling, Matthias

    2017-01-01

    Mixed penetrant sorption into ultra-thin films of a super-glassy polymer of intrinsic microporosity (PIM-1) was studied for the first time by using interference-enhanced in-situ spectroscopic ellipsometry. PIM-1 swelling and the concurrent changes in its refractive index were determined in ultra-thin (12 - 14 nm) films exposed to pure and mixed penetrants. The penetrants included water, n-hexane and ethanol and were chosen based on their significantly different penetrant-penetrant and penetrant-polymer affinities. This allowed studying microporous polymer responses at diverse ternary compositions and revealed effects such as competition for the sorption sites (for water / n-hexane or ethanol / n-hexane) or enhancement in sorption of typically weakly sorbing water in the presence of more highly sorbing ethanol. The results reveal details of the mutual sorption effects which often complicate comprehension of glassy polymers' behavior in applications such as high-performance membranes, adsorbents or catalysts. Mixed-penetrant effects are typically very challenging to study directly and their understanding is necessary owing to a broadly recognized inadequacy of simple extrapolations from measurements in pure component environment.

  2. Mixed-Penetrant Sorption in Ultra-Thin Films of Polymer of Intrinsic Microporosity PIM-1

    KAUST Repository

    Ogieglo, Wojciech

    2017-10-12

    Mixed penetrant sorption into ultra-thin films of a super-glassy polymer of intrinsic microporosity (PIM-1) was studied for the first time by using interference-enhanced in-situ spectroscopic ellipsometry. PIM-1 swelling and the concurrent changes in its refractive index were determined in ultra-thin (12 - 14 nm) films exposed to pure and mixed penetrants. The penetrants included water, n-hexane and ethanol and were chosen based on their significantly different penetrant-penetrant and penetrant-polymer affinities. This allowed studying microporous polymer responses at diverse ternary compositions and revealed effects such as competition for the sorption sites (for water / n-hexane or ethanol / n-hexane) or enhancement in sorption of typically weakly sorbing water in the presence of more highly sorbing ethanol. The results reveal details of the mutual sorption effects which often complicate comprehension of glassy polymers\\' behavior in applications such as high-performance membranes, adsorbents or catalysts. Mixed-penetrant effects are typically very challenging to study directly and their understanding is necessary owing to a broadly recognized inadequacy of simple extrapolations from measurements in pure component environment.

  3. How Do Organic Vapors Swell Ultra-Thin PIM-1 Films?

    KAUST Repository

    Ogieglo, Wojciech

    2017-06-22

    Dynamic sorption of ethanol and toluene vapor into ultra-thin supported PIM-1 films down to 6 nm are studied with a combination of in-situ spectroscopic ellipsometry and in-situ X-ray reflectivity. Both ethanol and toluene significantly swell the PIM-1 matrix and, at the same time, induce persistent structural relaxations of the frozen-in glassy PIM-1 morphology. For ethanol below 20 nm three effects were identified. First, the swelling magnitude at high vapor pressures is reduced by about 30% as compared to thicker films. Second, at low penetrant activities (below 0.3 p/p0) films below 20 nm are able to absorb slightly more penetrant as compared with thicker films despite similar swelling magnitude. Third, for the ultra-thin films the onset of the dynamic penetrant-induced glass transition Pg has been found to shift to higher values indicating higher resistance to plasticization. All of these effects are consistent with a view where immobilization of the super-glassy PIM-1 at the substrate surface leads to an arrested, even more rigid and plasticization-resistant, yet still very open, microporous structure. PIM-1 in contact with the larger and more condensable toluene shows very complex, heterogeneous swelling dynamics and two distinct penetrant-induced relaxation phenomena, probably associated with the film outer surface and the bulk, are detected. Following the direction of the penetrant\\'s diffusion the surface seems to plasticize earlier than the bulk and the two relaxations remain well separated down to 6 nm film thickness, where they remarkably merge to form just a single relaxation.

  4. Thermodynamical fluctuations and critical behavior in weakly disordered YBCO thin and ultra-thin films

    International Nuclear Information System (INIS)

    Lesueur, J.; Aprili, M.; Degoy, S.; Chambonnet, D.; Keller, D.

    1996-01-01

    The specific role of disorder in the transport properties of YBCO has been investigated, using both light-ion irradiation of thin films to finely tune the amount of atomic disorder, and ultra-thin films grown to study possible dimensional effects. For weak disorder, the samples display a resistive transition typical of the mean-field paraconductive regime of a homogeneous media, well described by the Lawrence and Doniach model for layered superconductors. As the disorder increases, two effects take place. First, the c-axis coherence length becomes shorter, leading to a more anisotropic material, as shown by the excess conductivity above T c . Second, an incipient granularity is revealed, leading to a less sharper transition, which is analyzed within the random 3D XY critical model for the paracoherence transition. Two main results are derived: an experimental test of the Ginzburg criteria for the paracoherence transition, and a new fluctuation regime in nanometric grain size superconductors

  5. Structural study and fabrication of nano-pattern on ultra thin film of Ag grown by magnetron sputtering

    International Nuclear Information System (INIS)

    Banerjee, S.; Mukherjee, S.; Kundu, S.

    2001-01-01

    We present the structural study of ultra thin Ag films using grazing incidence x-ray reflectivity and the modification of these films with the tip of an atomic force microscope. Ag thin films are deposited using dc magnetron sputtering on a Si(001) substrate. Initially, the growth of the film is carpet like and above a certain thickness (∼42 A) the film structure changes to form mounds. This ultra thin film of Ag having carpet-like growth can be modified by the tip of an atomic force microscope, which occurs due to the porous nature of the film. A periodic pattern of nanometer dimensions has been fabricated on this film using the atomic force microscope tip. (author)

  6. Solid-State Densification of Spun-Cast Self-Assembled Monolayers for Use in Ultra-Thin Hybrid Dielectrics.

    Science.gov (United States)

    Hutchins, Daniel O; Acton, Orb; Weidner, Tobias; Cernetic, Nathan; Baio, Joe E; Castner, David G; Ma, Hong; Jen, Alex K-Y

    2012-11-15

    Ultra-thin self-assembled monolayer (SAM)-oxide hybrid dielectrics have gained significant interest for their application in low-voltage organic thin film transistors (OTFTs). A [8-(11-phenoxy-undecyloxy)-octyl]phosphonic acid (PhO-19-PA) SAM on ultrathin AlO x (2.5 nm) has been developed to significantly enhance the dielectric performance of inorganic oxides through reduction of leakage current while maintaining similar capacitance to the underlying oxide structure. Rapid processing of this SAM in ambient conditions is achieved by spin coating, however, as-cast monolayer density is not sufficient for dielectric applications. Thermal annealing of a bulk spun-cast PhO-19-PA molecular film is explored as a mechanism for SAM densification. SAM density, or surface coverage, and order are examined as a function of annealing temperature. These SAM characteristics are probed through atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and near edge X-ray absorption fine structure spectroscopy (NEXAFS). It is found that at temperatures sufficient to melt the as-cast bulk molecular film, SAM densification is achieved; leading to a rapid processing technique for high performance SAM-oxide hybrid dielectric systems utilizing a single wet processing step. To demonstrate low-voltage devices based on this hybrid dielectric (with leakage current density of 7.7×10 -8 A cm -2 and capacitance density of 0.62 µF cm -2 at 3 V), pentacene thin-film transistors (OTFTs) are fabricated and yield sub 2 V operation and charge carrier mobilites of up to 1.1 cm 2 V -1 s -1 .

  7. Comment on 'extrinsic versus intrinsic ferroelectric switching : experimental investigations using ultra-thin PVDF Langmuir-Blodgett films'

    NARCIS (Netherlands)

    Naber, R.C.G.; Blom, P.W.M.; de Leeuw, DM

    2006-01-01

    Previous work on ultra-thin P(VDF-TrFE) Langmuir-Blodgett films has indicated a transition from extrinsic to intrinsic ferroelectric switching. The lack of several key features of intrinsic switching in the experimental work reported by Kliem et al argues against intrinsic switching. In this Comment

  8. Probing the surface swelling in ultra-thin supported polystyrene films during case II diffusion of n-hexane

    NARCIS (Netherlands)

    Ogieglo, Wojciech; Wormeester, Herbert; Wessling, Matthias; Benes, Nieck Edwin

    2013-01-01

    In situ time-resolved spectroscopic ellipsometry is used to study the dynamics of n-hexane diffusion into, and the corresponding induced swelling of, ultra-thin polystyrene films. The experimental conditions are carefully selected to facilitate the observation of anomalous Case II diffusion in the

  9. Mechanical properties of ultra-thin HfO2 films studied by nano scratches tests

    International Nuclear Information System (INIS)

    Fu, Wei-En; Chang, Yong-Qing; Chang, Chia-Wei; Yao, Chih-Kai; Liao, Jiunn-Der

    2013-01-01

    10-nm-thick atomic layer deposited HfO 2 films were characterized in terms of wear resistance and indentation hardness to investigate the thermal annealing induced impacts on mechanical properties. The wear resistance of ultra-thin films at low loads was characterized using nano-scratch tests with an atomic force microscope. The depth of the nano-scratches decreases with increasing annealing temperature, indicating that the hardness of the annealed films increases with the annealing temperatures. Surface nanoindentation was also performed to confirm the nanoscratch test results. The hardness variation of the annealed films is due to the generation of HfSi x O y induced by the thermal annealing. X-ray photoelectron spectroscopy measurements proved that the hardness of formed HfSi x O y with increasing annealing temperatures. The existence of HfSi x O y broadens the interface, and causes the increase of the interfacial layer thickness. As a result, the surface hardness increases with the increasing HfSi x O y induced by the thermal annealing. - Highlights: ► Mechanical properties of HfO 2 films were assessed by nano-scratch and indentation. ► Scratch depth of HfO 2 films decreased with the increase of annealing temperatures. ► Nano-hardness of HfO 2 films increased with the increase of annealing temperatures

  10. Dynamics and morphology of chiral magnetic bubbles in perpendicularly magnetized ultra-thin films

    Science.gov (United States)

    Sarma, Bhaskarjyoti; Garcia-Sanchez, Felipe; Nasseri, S. Ali; Casiraghi, Arianna; Durin, Gianfranco

    2018-06-01

    We study bubble domain wall dynamics using micromagnetic simulations in perpendicularly magnetized ultra-thin films with disorder and Dzyaloshinskii-Moriya interaction. Disorder is incorporated into the material as grains with randomly distributed sizes and varying exchange constant at the edges. As expected, magnetic bubbles expand asymmetrically along the axis of the in-plane field under the simultaneous application of out-of-plane and in-plane fields. Remarkably, the shape of the bubble has a ripple-like part which causes a kink-like (steep decrease) feature in the velocity versus in-plane field curve. We show that these ripples originate due to the nucleation and interaction of vertical Bloch lines. Furthermore, we show that the Dzyaloshinskii-Moriya interaction field is not constant but rather depends on the in-plane field. We also extend the collective coordinate model for domain wall motion to a magnetic bubble and compare it with the results of micromagnetic simulations.

  11. Structure of a zinc oxide ultra-thin film on Rh(100)

    Energy Technology Data Exchange (ETDEWEB)

    Yuhara, J.; Kato, D.; Matsui, T. [Department of Materials, Physics and Energy Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Mizuno, S. [Department of Molecular and Material Sciences, Kyushu University, Kasuga, Fukuoka 816–8580 (Japan)

    2015-11-07

    The structural parameters of ultra-thin zinc oxide films on Rh(100) are investigated using low-energy electron diffraction intensity (LEED I–V) curves, scanning tunneling microscopy (STM), and first-principles density functional theory (DFT) calculations. From the analysis of LEED I–V curves and DFT calculations, two optimized models A and B are determined. Their structures are basically similar to the planer h-BN ZnO(0001) structure, although some oxygen atoms protrude from the surface, associated with an in-plane shift of Zn atoms. From a comparison of experimental STM images and simulated STM images, majority and minority structures observed in the STM images represent the two optimized models A and B, respectively.

  12. Self organized striping in ultra thin polymer films near melt: An investigation using Monte Carlo simulation

    Science.gov (United States)

    Singh, Satya Pal

    2018-05-01

    This paper work presents the results of Monte Carlo simulation performed for ultra thin short chained polymer films near melt, under strong confinement. Thin polymer films get ruptured when annealed above their glass transition temperatures. The pattern formations are generally explained on the basis of spinodal mechanism, if the thickness of the film is of the order of few tens of nanometers i.e. film seems to tear apart in strips. The free end segments of the chains are more dynamic and coalescence into one another. This process seems to dominate over the spinodal waves resulting into a different type of dynamics. Polymer chains with 30 monomers are taken. 160, 200 and 240 chains are taken for three different cases of the studies. The three cases correspond to three different thickness of the films with 8, 10 and 12 layers of chains along direction perpendicular to the confining substrates. The bottom surface has affinity to monomers, whereas the upper surface has hard wall interaction with the monomers. Different time micrographs of the films are plotted along with density distributions of the monomers to explore the process.

  13. Enhancement of Heat and Mass Transfer in Mechanically Contstrained Ultra Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Kevin Drost; Jim Liburdy; Brian Paul; Richard Peterson

    2005-01-01

    Oregon State University (OSU) and the Pacific Northwest National Laboratory (PNNL) were funded by the U.S. Department of Energy to conduct research focused on resolving the key technical issues that limited the deployment of efficient and extremely compact microtechnology based heat actuated absorption heat pumps and gas absorbers. Success in demonstrating these technologies will reduce the main barriers to the deployment of a technology that can significantly reduce energy consumption in the building, automotive and industrial sectors while providing a technology that can improve our ability to sequester CO{sub 2}. The proposed research cost $939,477. $539,477 of the proposed amount funded research conducted at OSU while the balance ($400,000) was used at PNNL. The project lasted 42 months and started in April 2001. Recent developments at the Pacific Northwest National Laboratory and Oregon State University suggest that the performance of absorption and desorption systems can be significantly enhanced by the use of an ultra-thin film gas/liquid contactor. This device employs microtechnology-based structures to mechanically constrain the gas/liquid interface. This technology can be used to form very thin liquid films with a film thickness less then 100 microns while still allowing gas/liquid contact. When the resistance to mass transfer in gas desorption and absorption is dominated by diffusion in the liquid phase the use of extremely thin films (<100 microns) for desorption and absorption can radically reduce the size of a gas desorber or absorber. The development of compact absorbers and desorbers enables the deployment of small heat-actuated absorption heat pumps for distributed space heating and cooling applications, heat-actuated automotive air conditioning, manportable cooling, gas absorption units for the chemical process industry and the development of high capacity CO{sub 2} absorption devices for CO{sub 2} collection and sequestration. The energy

  14. Probing stress state and phase content in ultra-thin Ta films

    International Nuclear Information System (INIS)

    Whitacre, J.F.; Yalisove, S.M.; Bilello, J.C.; Rek, Z.U.

    1998-01-01

    Ta films 25 angstrom to 200 angstrom in thickness were sputter-deposited using different sputter gas (Ar) pressures and cathode power settings. The average in-plane stresses were determined using double crystal diffraction topography (DCDT). X-ray analysis (using the grazing incidence x-ray scattering (GIXS) geometry) was performed using a synchrotron light source. To study microstructure and phase content, transmission electron microscopy (TEM) and transmission electron diffraction (TED) were used. Well resolved x-ray patterns were collected for all of the films. The DCDT stress data was found to be consistent with stress effects evidence in the GIXS data. In general, residual stress state was not strongly dependent upon Ar pressure. The strongest evidence of amorphous content was found in both x-ray and TED data taken from 25 angstrom thick films deposited using 2mTorr Ar pressure and 460 W cathode power. These results show that it is possible to create and study ultra-thin Ta films which possess a range of residual stresses and phase compositions

  15. Characterization of ultra-thin TiO2 films grown on Mo(112)

    International Nuclear Information System (INIS)

    Kumar, D.; Chen, M.S.; Goodman, D.W.

    2006-01-01

    Ultra-thin TiO 2 films were grown on a Mo(112) substrate by stepwise vapor depositing of Ti onto the sample surface followed by oxidation at 850 K. X-ray photoelectron spectroscopy showed that the Ti 2p peak position shifts from lower to higher binding energy with an increase in the Ti coverage from sub- to multilayer. The Ti 2p peak of a TiO 2 film with more than a monolayer coverage can be resolved into two peaks, one at 458.1 eV corresponding to the first layer, where Ti atoms bind to the substrate Mo atoms through Ti-O-Mo linkages, and a second feature at 458.8 eV corresponding to multilayer TiO 2 where the Ti atoms are connected via Ti-O-Ti linkages. Based on these assignments, the single Ti 2p 3/2 peak at 455.75 eV observed for the Mo(112)-(8 x 2)-TiO x monolayer film can be assigned to Ti 3+ , consistent with our previous results obtained with high-resolution electron energy loss spectroscopy

  16. Magnetic structures in ultra-thin Holmium films: Influence of external magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, L.J. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, Natal 59600-900, RN (Brazil); Departamento de Física, Universidade do Estado do Rio Grande do Norte, Mossoró 59625-620, RN (Brazil); Mello, V.D. [Departamento de Física, Universidade do Estado do Rio Grande do Norte, Mossoró 59625-620, RN (Brazil); Anselmo, D.H.A.L. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, Natal 59600-900, RN (Brazil); Vasconcelos, M.S., E-mail: mvasconcelos@ect.ufrn.br [Escola de Ciência e Tecnologia, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, RN (Brazil)

    2015-03-01

    We address the magnetic phases in very thin Ho films at the temperature interval between 20 K and 132 K. We show that slab size, surface effects and magnetic field due to spin ordering impact significantly the magnetic phase diagram. Also we report that there is a relevant reduction of the external field strength required to saturate the magnetization and for ultra-thin films the helical state does not form. We explore the specific heat and the susceptibility as auxiliary tools to discuss the nature of the phase transitions, when in the presence of an external magnetic field and temperature effects. The presence of an external field gives rise to the magnetic phase Fan and the spin-slip structures. - Highlights: • We analyze the magnetic phases of very thin Ho films in the temperature interval 20–132 K. • We show that slab size, etc. due to spin ordering may impact the magnetic phase diagram. • All magnetic phase transitions, for strong magnetic fields, are marked by the specific heat. • The presence of an external field gives rise to the magnetic phase Fan and the spin-slip one.

  17. Solid-state densification of spun-cast self-assembled monolayers for use in ultra-thin hybrid dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Hutchins, Daniel O.; Acton, Orb [Department of Materials Science and Engineering, University of Washington, Seattle, WA 98195 (United States); Weidner, Tobias [Department of Bioengineering, University of Washington, Seattle, WA 98195 (United States); Cernetic, Nathan [Department of Materials Science and Engineering, University of Washington, Seattle, WA 98195 (United States); Baio, Joe E. [Department of Chemical Engineering, University of Washington, Seattle, WA 98195 (United States); Castner, David G. [Department of Bioengineering, University of Washington, Seattle, WA 98195 (United States); Department of Chemical Engineering, University of Washington, Seattle, WA 98195 (United States); Ma, Hong, E-mail: hma@uw.edu [Department of Materials Science and Engineering, University of Washington, Seattle, WA 98195 (United States); Jen, Alex K.-Y., E-mail: ajen@uw.edu [Department of Materials Science and Engineering, University of Washington, Seattle, WA 98195 (United States); Department of Chemistry, University of Washington, Seattle, WA 98195 (United States)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer Rapid processing of SAM in ambient conditions is achieved by spin coating. Black-Right-Pointing-Pointer Thermal annealing of a bulk spun-cast molecular film is explored as a mechanism for SAM densification. Black-Right-Pointing-Pointer High-performance SAM-oxide hybrid dielectric is obtained utilizing a single wet processing step. - Abstract: Ultra-thin self-assembled monolayer (SAM)-oxide hybrid dielectrics have gained significant interest for their application in low-voltage organic thin film transistors (OTFTs). A [8-(11-phenoxy-undecyloxy)-octyl]phosphonic acid (PhO-19-PA) SAM on ultrathin AlO{sub x} (2.5 nm) has been developed to significantly enhance the dielectric performance of inorganic oxides through reduction of leakage current while maintaining similar capacitance to the underlying oxide structure. Rapid processing of this SAM in ambient conditions is achieved by spin coating, however, as-cast monolayer density is not sufficient for dielectric applications. Thermal annealing of a bulk spun-cast PhO-19-PA molecular film is explored as a mechanism for SAM densification. SAM density, or surface coverage, and order are examined as a function of annealing temperature. These SAM characteristics are probed through atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and near edge X-ray absorption fine structure spectroscopy (NEXAFS). It is found that at temperatures sufficient to melt the as-cast bulk molecular film, SAM densification is achieved; leading to a rapid processing technique for high performance SAM-oxide hybrid dielectric systems utilizing a single wet processing step. To demonstrate low-voltage devices based on this hybrid dielectric (with leakage current density of 7.7 Multiplication-Sign 10{sup -8} A cm{sup -2} and capacitance density of 0.62 {mu}F cm{sup -2} at 3 V), pentacene thin-film transistors (OTFTs) are fabricated and yield sub 2 V operation and charge carrier mobilites of up to

  18. Flexible Mixed-Potential-Type (MPT) NO₂ Sensor Based on An Ultra-Thin Ceramic Film.

    Science.gov (United States)

    You, Rui; Jing, Gaoshan; Yu, Hongyan; Cui, Tianhong

    2017-07-29

    A novel flexible mixed-potential-type (MPT) sensor was designed and fabricated for NO₂ detection from 0 to 500 ppm at 200 °C. An ultra-thin Y₂O₃-doped ZrO₂ (YSZ) ceramic film 20 µm thick was sandwiched between a heating electrode and reference/sensing electrodes. The heating electrode was fabricated by a conventional lift-off process, while the porous reference and the sensing electrodes were fabricated by a two-step patterning method using shadow masks. The sensor's sensitivity is achieved as 58.4 mV/decade at the working temperature of 200 °C, as well as a detection limit of 26.7 ppm and small response time of less than 10 s at 200 ppm. Additionally, the flexible MPT sensor demonstrates superior mechanical stability after bending over 50 times due to the mechanical stability of the YSZ ceramic film. This simply structured, but highly reliable flexible MPT NO₂ sensor may lead to wide application in the automobile industry for vehicle emission systems to reduce NO₂ emissions and improve fuel efficiency.

  19. Oxygen-enabled control of Dzyaloshinskii-Moriya Interaction in ultra-thin magnetic films

    KAUST Repository

    Belabbes, Abderrezak

    2016-04-22

    The search for chiral magnetic textures in systems lacking spatial inversion symmetry has attracted a massive amount of interest in the recent years with the real space observation of novel exotic magnetic phases such as skyrmions lattices, but also domain walls and spin spirals with a defined chirality. The electrical control of these textures offers thrilling perspectives in terms of fast and robust ultrahigh density data manipulation. A powerful ingredient commonly used to stabilize chiral magnetic states is the so-called Dzyaloshinskii-Moriya interaction (DMI) arising from spin-orbit coupling in inversion asymmetric magnets. Such a large antisymmetric exchange has been obtained at interfaces between heavy metals and transition metal ferromagnets, resulting in spin spirals and nanoskyrmion lattices. Here, using relativistic first-principles calculations, we demonstrate that the magnitude and sign of DMI can be entirely controlled by tuning the oxygen coverage of the magnetic film, therefore enabling the smart design of chiral magnetism in ultra-thin films. We anticipate that these results extend to other electronegative ions and suggest the possibility of electrical tuning of exotic magnetic phases.

  20. Ultra-thin films of polysilsesquioxanes possessing 3-methacryloxypropyl groups as gate insulator for organic field-effect transistors

    International Nuclear Information System (INIS)

    Nakahara, Yoshio; Kawa, Haruna; Yoshiki, Jun; Kumei, Maki; Yamamoto, Hiroyuki; Oi, Fumio; Yamakado, Hideo; Fukuda, Hisashi; Kimura, Keiichi

    2012-01-01

    Polysilsesquioxanes (PSQs) possessing 3-methacryloxypropyl groups as an organic moiety of the side chain were synthesized by sol–gel condensation copolymerization of the corresponding trialkoxysilanes. The ultra-thin PSQ film with a radical initiator and a cross-linking agent was prepared by a spin-coating method, and the film was cured integrally at low temperatures of less than 120 °C through two different kinds of polymeric reactions, which were radical polymerization of vinyl groups and sol–gel condensation polymerization of terminated silanol and alkoxy groups. The obtained PSQ film showed the almost perfect solubilization resistance to acetone, which is a good solvent of PSQ before polymerization. It became clear by atomic force microscopy observation that the surface of the PSQ film was very smooth at a nano-meter level. Furthermore, pentacene-based organic field-effect transistor (OFET) with the PSQ film as a gate insulator showed typical p-channel enhancement mode operation characteristics and therefore the ultra-thin PSQ film has the potential to be applicable for solution-processed OFET systems. - Highlights: ► Polysilsesquioxanes (PSQs) possessing 3-methacryloxypropyl groups were synthesized. ► The ultra-thin PSQ film could be cured at low temperatures of less than 120 °C. ► The PSQ film showed the almost perfect solubilization resistance to organic solvent. ► The surface of the PSQ film was very smooth at a nano-meter level. ► Pentacene-based organic field-effect transistor with the PSQ film was fabricated.

  1. Ultra-thin films of polysilsesquioxanes possessing 3-methacryloxypropyl groups as gate insulator for organic field-effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Nakahara, Yoshio; Kawa, Haruna [Department of Applied Chemistry, Faculty of Systems Engineering, Wakayama University, 930 Sakae-dani, Wakayama 640-8510 (Japan); Yoshiki, Jun [Division of Information and Electronic Engineering, Faculty of Engineering, Muroran Institute of Technology, 27-1 Mizumoto-cho, Muroran 050-8585 (Japan); Kumei, Maki; Yamamoto, Hiroyuki; Oi, Fumio [Konishi Chemical IND. Co., LTD., 3-4-77 Kozaika, Wakayama 641-0007 (Japan); Yamakado, Hideo [Department of Applied Chemistry, Faculty of Systems Engineering, Wakayama University, 930 Sakae-dani, Wakayama 640-8510 (Japan); Fukuda, Hisashi [Division of Engineering for Composite Functions, Faculty of Engineering, Muroran Institute of Technology, 27-1 Mizumoto-cho, Muroran 050-8585 (Japan); Kimura, Keiichi, E-mail: kkimura@center.wakayama-u.ac.jp [Department of Applied Chemistry, Faculty of Systems Engineering, Wakayama University, 930 Sakae-dani, Wakayama 640-8510 (Japan)

    2012-10-01

    Polysilsesquioxanes (PSQs) possessing 3-methacryloxypropyl groups as an organic moiety of the side chain were synthesized by sol-gel condensation copolymerization of the corresponding trialkoxysilanes. The ultra-thin PSQ film with a radical initiator and a cross-linking agent was prepared by a spin-coating method, and the film was cured integrally at low temperatures of less than 120 Degree-Sign C through two different kinds of polymeric reactions, which were radical polymerization of vinyl groups and sol-gel condensation polymerization of terminated silanol and alkoxy groups. The obtained PSQ film showed the almost perfect solubilization resistance to acetone, which is a good solvent of PSQ before polymerization. It became clear by atomic force microscopy observation that the surface of the PSQ film was very smooth at a nano-meter level. Furthermore, pentacene-based organic field-effect transistor (OFET) with the PSQ film as a gate insulator showed typical p-channel enhancement mode operation characteristics and therefore the ultra-thin PSQ film has the potential to be applicable for solution-processed OFET systems. - Highlights: Black-Right-Pointing-Pointer Polysilsesquioxanes (PSQs) possessing 3-methacryloxypropyl groups were synthesized. Black-Right-Pointing-Pointer The ultra-thin PSQ film could be cured at low temperatures of less than 120 Degree-Sign C. Black-Right-Pointing-Pointer The PSQ film showed the almost perfect solubilization resistance to organic solvent. Black-Right-Pointing-Pointer The surface of the PSQ film was very smooth at a nano-meter level. Black-Right-Pointing-Pointer Pentacene-based organic field-effect transistor with the PSQ film was fabricated.

  2. Anomalous aging and strain induced time dependent phenomena in ultra-thin La0.65Ca0.35MnO3 films

    International Nuclear Information System (INIS)

    Egilmez, M.; Saber, M.M.; Abdelhadi, M.; Chow, K.H.; Jung, J.

    2011-01-01

    We have shown that ultra-thin La 0.65 Ca 0.35 MnO 3 films exhibit strong metastable behavior. The resistance can vary with time significantly, suggesting that a state of dynamic phase separation exists whereby one phase grows at the expense of another. Physical properties associated with the metastable behavior have been investigated on the films grown on different substrates. We have found that ultra-thin films age much faster than the thicker counterparts and more interestingly the metastability in the resistance of these films enhanced when aged. -- Highlights: → Ultra-thin La 0.67 Ca 0.33 MnO 3 films exhibit metastable behavior. → Physical properties associated with metastable behavior have been investigated. → The metastability in resistance of the films enhanced when films are aged. → Relaxation rates were used as a relative measure the metastability. → The metastable behavior is sensitive to the strain state of the film.

  3. Silicon nitride gradient film as the underlayer of ultra-thin tetrahedral amorphous carbon overcoat for magnetic recording slider

    Energy Technology Data Exchange (ETDEWEB)

    Wang Guigen, E-mail: wanggghit@yahoo.com [Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055 (China); Kuang Xuping; Zhang Huayu; Zhu Can [Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055 (China); Han Jiecai [Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055 (China); Center for Composite Materials, Harbin Institute of Technology, Harbin 150080 (China); Zuo Hongbo [Center for Composite Materials, Harbin Institute of Technology, Harbin 150080 (China); Ma Hongtao [SAE Technologies Development (Dongguan) Co., Ltd., Dongguan 523087 (China)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer The ultra-thin carbon films with different silicon nitride (Si-N) film underlayers were prepared. Black-Right-Pointing-Pointer It highlighted the influences of Si-N underlayers. Black-Right-Pointing-Pointer The carbon films with Si-N underlayers obtained by nitriding especially at the substrate bias of -150 V, can exhibit better corrosion protection properties - Abstract: There are higher technical requirements for protection overcoat of magnetic recording slider used in high-density storage fields for the future. In this study, silicon nitride (Si-N) composition-gradient films were firstly prepared by nitriding of silicon thin films pre-sputtered on silicon wafers and magnetic recording sliders, using microwave electron cyclotron resonance plasma source. The ultra-thin tetrahedral amorphous carbon films were then deposited on the Si-N films by filtered cathodic vacuum arc method. Compared with amorphous carbon overcoats with conventional silicon underlayers, the overcoats with Si-N underlayers obtained by plasma nitriding especially at the substrate bias of -150 V, can provide better corrosion protection for high-density magnetic recording sliders.

  4. Silicon nitride gradient film as the underlayer of ultra-thin tetrahedral amorphous carbon overcoat for magnetic recording slider

    International Nuclear Information System (INIS)

    Wang Guigen; Kuang Xuping; Zhang Huayu; Zhu Can; Han Jiecai; Zuo Hongbo; Ma Hongtao

    2011-01-01

    Highlights: ► The ultra-thin carbon films with different silicon nitride (Si-N) film underlayers were prepared. ► It highlighted the influences of Si-N underlayers. ► The carbon films with Si-N underlayers obtained by nitriding especially at the substrate bias of −150 V, can exhibit better corrosion protection properties - Abstract: There are higher technical requirements for protection overcoat of magnetic recording slider used in high-density storage fields for the future. In this study, silicon nitride (Si-N) composition-gradient films were firstly prepared by nitriding of silicon thin films pre-sputtered on silicon wafers and magnetic recording sliders, using microwave electron cyclotron resonance plasma source. The ultra-thin tetrahedral amorphous carbon films were then deposited on the Si-N films by filtered cathodic vacuum arc method. Compared with amorphous carbon overcoats with conventional silicon underlayers, the overcoats with Si-N underlayers obtained by plasma nitriding especially at the substrate bias of −150 V, can provide better corrosion protection for high-density magnetic recording sliders.

  5. Comment on 'Extrinsic versus intrinsic ferroelectric switching: experimental investigations using ultra-thin PVDF Langmuir-Blodgett films'

    International Nuclear Information System (INIS)

    Naber, R C G; Blom, P W M; Leeuw, D M de

    2006-01-01

    Previous work on ultra-thin P(VDF-TrFE) Langmuir-Blodgett films has indicated a transition from extrinsic to intrinsic ferroelectric switching. The lack of several key features of intrinsic switching in the experimental work reported by Kliem et al argues against intrinsic switching. In this Comment we discuss two published papers and new experimental results that support a lack of intrinsic switching and point to the conclusion that the thickness dependence of the Langmuir-Blodgett films is due to the influence of the electrode interfaces. (comment)

  6. Ultra-thin Glass Film Coated with Graphene: A New Material for Spontaneous Emission Enhancement of Quantum Emitter

    Institute of Scientific and Technical Information of China (English)

    Lu Sun; Chun Jiang

    2015-01-01

    We propose an ultra-thin glass film coated with graphene as a new kind of surrounding material which can greatly enhance spontaneous emission rate(SER) of dipole emitter embedded in it. With properly designed parameters,numerical results show that SER-enhanced factors as high as 1.286 9 106 can be achieved. The influences of glass film thickness and chemical potential/doping level of graphene on spontaneous emission enhancement are also studied in this paper. A comparison is made between graphene and other coating materials such as gold and silver to see their performances in SER enhancement.

  7. Magnetic field induced superconductor-insulator transitions for ultra-thin Bi films on the different underlayers

    International Nuclear Information System (INIS)

    Makise, K; Kawaguti, T; Shinozaki, B

    2009-01-01

    This work shows the experimental results of the superconductor-insulator (S-I) transition for ultra-thin Bi films in magnetic fields. The quench-condensed (q-c) Bi film onto insulating underlayers have been interpreted to be homogeneous. In contrast, the Bi film without underlayers has been regarded as a granular film. The electrical transport properties of ultra-thin metal films near the S-I transition depend on the structure of the film. In order to confirm the effect of the underlayer to the homogeneity of the superconducting films, we investigate the characteristics of S-I transitions of q-c nominally homogeneous Bi films on underlayers of two insulating materials, SiO, and Sb. Under almost the same deposition condition except for the material of underlayer, we prepared the Bi films by repeating the additional deposition and performed in-situ electrical measurement. It is found that the transport properties near the S-I transitions show the remarkable difference between two films on different underlayers. As for Bi films on SiO, it turned out that the temperature dependence of resistance per square R sq (T) of the field-tuned transition and the thickness-tuned transition shows similar behavior; it was a thermally activated form. On the other hand, the R sq (T) of Bi films on Sb for thickness-tuned S-I transition showed logarithmic temperature dependence, but that for field-tuned S-I transition showed a thermally activated form.

  8. Misfit strain-film thickness phase diagrams and related electromechanical properties of epitaxial ultra-thin lead zirconate titanate films

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Q.Y.; Mahjoub, R. [School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Alpay, S.P. [Materials Science and Engineering Program and Institute of Materials Science, University of Connecticut, Storrs, CT 06269 (United States); Nagarajan, V., E-mail: nagarajan@unsw.edu.au [School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052 (Australia)

    2010-02-15

    The phase stability of ultra-thin (0 0 1) oriented ferroelectric PbZr{sub 1-x}Ti{sub x}O{sub 3} (PZT) epitaxial thin films as a function of the film composition, film thickness, and the misfit strain is analyzed using a non-linear Landau-Ginzburg-Devonshire thermodynamic model taking into account the electrical and mechanical boundary conditions. The theoretical formalism incorporates the role of the depolarization field as well as the possibility of the relaxation of in-plane strains via the formation of microstructural features such as misfit dislocations at the growth temperature and ferroelastic polydomain patterns below the paraelectric-ferroelectric phase transformation temperature. Film thickness-misfit strain phase diagrams are developed for PZT films with four different compositions (x = 1, 0.9, 0.8 and 0.7) as a function of the film thickness. The results show that the so-called rotational r-phase appears in a very narrow range of misfit strain and thickness of the film. Furthermore, the in-plane and out-of-plane dielectric permittivities {epsilon}{sub 11} and {epsilon}{sub 33}, as well as the out-of-plane piezoelectric coefficients d{sub 33} for the PZT thin films, are computed as a function of misfit strain, taking into account substrate-induced clamping. The model reveals that previously predicted ultrahigh piezoelectric coefficients due to misfit-strain-induced phase transitions are practically achievable only in an extremely narrow range of film thickness, composition and misfit strain parameter space. We also show that the dielectric and piezoelectric properties of epitaxial ferroelectric films can be tailored through strain engineering and microstructural optimization.

  9. Acoustic Phonons and Mechanical Properties of Ultra-Thin Porous Low-k Films: A Surface Brillouin Scattering Study

    Science.gov (United States)

    Zizka, J.; King, S.; Every, A.; Sooryakumar, R.

    2018-04-01

    To reduce the RC (resistance-capacitance) time delay of interconnects, a key development of the past 20 years has been the introduction of porous low-k dielectrics to replace the traditional use of SiO2. Moreover, in keeping pace with concomitant reduction in technology nodes, these low-k materials have reached thicknesses below 100 nm wherein the porosity becomes a significant fraction of the film volume. The large degree of porosity not only reduces mechanical strength of the dielectric layer but also renders a need for non-destructive approaches to measure the mechanical properties of such ultra-thin films within device configurations. In this study, surface Brillouin scattering (SBS) is utilized to determine the elastic constants, Poisson's ratio, and Young's modulus of these porous low-k SiOC:H films (˜ 25-250 nm thick) grown on Si substrates by probing surface acoustic phonons and their dispersions.

  10. Ab initio thermodynamics for the growth of ultra-thin Cu film on a perfect Mg O(001) surface

    Energy Technology Data Exchange (ETDEWEB)

    Zhukovskii, Yuri F. [Institute for Solid State Physics, University of Latvia, Kengaraga str. 8, Riga LV-1063 (Latvia)]. E-mail: quantzh@latnet.lv; Fuks, David [Materials Engineering Department, Ben-Gurion University of the Negev, POB 653, Beer-Sheva IL-84105 (Israel); Kotomin, Eugene A. [Institute for Solid State Physics, University of Latvia, Kengaraga str. 8, Riga LV-1063 (Latvia); Dorfman, Simon [Department of Physics, Israel Institute of Technology-Technion, Haifa IL-32000 (Israel)

    2005-12-15

    Controlled growth of thin metallic films on oxide substrates is important for numerous micro-and nano electronic applications. Our ab initio study is devoted to the periodic slab simulations for a series of ordered 2a Cu superlattices on the regular Mg O(001) substrate. Submonolayer and monolayer substrate Cu coverages were calculated using the Daft-Gaga method, as implemented into the Crystal-98 code. The results of ab initio calculations have been combined with thermodynamic theory which allows US to predict the growth mode of ultra-thin metal films (spinodal decomposition vs. nucleation-and-growth regime) as a function of the metal coverage and the temperature, and to estimate the metal density in clusters. We show that 3a cluster formation becomes predominant already at low Cu coverages, in agreement with the experiment.

  11. Ab initio thermodynamics for the growth of ultra-thin Cu film on a perfect Mg O(001) surface

    International Nuclear Information System (INIS)

    Zhukovskii, Yuri F.; Fuks, David; Kotomin, Eugene A.; Dorfman, Simon

    2005-01-01

    Controlled growth of thin metallic films on oxide substrates is important for numerous micro-and nano electronic applications. Our ab initio study is devoted to the periodic slab simulations for a series of ordered 2a Cu superlattices on the regular Mg O(001) substrate. Submonolayer and monolayer substrate Cu coverages were calculated using the Daft-Gaga method, as implemented into the Crystal-98 code. The results of ab initio calculations have been combined with thermodynamic theory which allows US to predict the growth mode of ultra-thin metal films (spinodal decomposition vs. nucleation-and-growth regime) as a function of the metal coverage and the temperature, and to estimate the metal density in clusters. We show that 3a cluster formation becomes predominant already at low Cu coverages, in agreement with the experiment

  12. Molecular dynamics simulations of disjoining pressure effects in ultra-thin water films on a metal surface

    Science.gov (United States)

    Hu, Han; Sun, Ying

    2013-11-01

    Disjoining pressure, the excess pressure in an ultra-thin liquid film as a result of van der Waals interactions, is important in lubrication, wetting, flow boiling, and thin film evaporation. The classic theory of disjoining pressure is developed for simple monoatomic liquids. However, real world applications often utilize water, a polar liquid, for which fundamental understanding of disjoining pressure is lacking. In the present study, molecular dynamics (MD) simulations are used to gain insights into the effect of disjoining pressure in a water thin film. Our MD models were firstly validated against Derjaguin's experiments on gold-gold interactions across a water film and then verified against disjoining pressure in an argon thin film using the Lennard-Jones potential. Next, a water thin film adsorbed on a gold surface was simulated to examine the change of vapor pressure with film thickness. The results agree well with the classic theory of disjoining pressure, which implies that the polar nature of water molecules does not play an important role. Finally, the effects of disjoining pressure on thin film evaporation in nanoporous membrane and on bubble nucleation are discussed.

  13. Young's Modulus and Coefficient of Linear Thermal Expansion of ZnO Conductive and Transparent Ultra-Thin Films

    Directory of Open Access Journals (Sweden)

    Naoki Yamamoto

    2011-01-01

    Full Text Available A new technique for measuring Young's modulus of an ultra-thin film, with a thickness in the range of about 10 nm, was developed by combining an optical lever technique for measuring the residual stress and X-ray diffraction for measuring the strain in the film. The new technique was applied to analyze the mechanical properties of Ga-doped ZnO (GZO films, that have become the focus of significant attention as a substitute material for indium-tin-oxide transparent electrodes. Young's modulus of the as-deposited GZO films decreased with thickness; the values for 30 nm and 500 nm thick films were 205 GPa and 117 GPa, respectively. The coefficient of linear thermal expansion of the GZO films was measured using the new technique in combination with in-situ residual stress measurement during heat-cycle testing. GZO films with 30–100 nm thickness had a coefficient of linear thermal expansion in the range of 4.3 × 10−6 – 5.6 × 10−6 °C−1.

  14. Mechanical properties of ultra-thin HfO{sub 2} films studied by nano scratches tests

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Wei-En; Chang, Yong-Qing [Center for Measurement Standards, Industrial Technology Research Institute, Room 216, Building 8, 321, Kuang Fu Road Sec. 2, Hsinchu, Taiwan (China); Chang, Chia-Wei; Yao, Chih-Kai [Department of Materials Science and Engineering, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Liao, Jiunn-Der, E-mail: jdliao@mail.ncku.edu.tw [Department of Materials Science and Engineering, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Center for Micro/Nano Science and Technology, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China)

    2013-02-01

    10-nm-thick atomic layer deposited HfO{sub 2} films were characterized in terms of wear resistance and indentation hardness to investigate the thermal annealing induced impacts on mechanical properties. The wear resistance of ultra-thin films at low loads was characterized using nano-scratch tests with an atomic force microscope. The depth of the nano-scratches decreases with increasing annealing temperature, indicating that the hardness of the annealed films increases with the annealing temperatures. Surface nanoindentation was also performed to confirm the nanoscratch test results. The hardness variation of the annealed films is due to the generation of HfSi{sub x}O{sub y} induced by the thermal annealing. X-ray photoelectron spectroscopy measurements proved that the hardness of formed HfSi{sub x}O{sub y} with increasing annealing temperatures. The existence of HfSi{sub x}O{sub y} broadens the interface, and causes the increase of the interfacial layer thickness. As a result, the surface hardness increases with the increasing HfSi{sub x}O{sub y} induced by the thermal annealing. - Highlights: ► Mechanical properties of HfO{sub 2} films were assessed by nano-scratch and indentation. ► Scratch depth of HfO{sub 2} films decreased with the increase of annealing temperatures. ► Nano-hardness of HfO{sub 2} films increased with the increase of annealing temperatures.

  15. Structural characterization and comparison of iridium, platinum and gold/palladium ultra-thin film coatings for STM of biomolecules

    Energy Technology Data Exchange (ETDEWEB)

    Sebring, R.; Arendt, P.; Imai, B.; Bradbury, E.M.; Gatewood, J. [Los Alamos National Lab., NM (United States); Panitz, J. [Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Physics and Astronomy; Yau, P. [Univ. of California, Davis, CA (United States)

    1997-10-30

    Scanning tunneling microscopy (STM) is capable of atomic resolution and is ideally suited for imaging surfaces with uniform work function. A biological sample on a conducting substrate in air does not meet this criteria and requires a conductive coating for stable and reproducible STM imaging. In this paper, the authors describe the STM and transmission electron microscopy (TEM) characterization of ultra-thin ion-beam sputtered films of iridium and cathode sputtered gold/palladium and platinum films on highly ordered pyrolytic graphite (HOPG) which were developed for use as biomolecule coatings. The goals were the development of metal coatings sufficiently thin and fine grained that 15--20 {angstrom} features of biological molecules could be resolved using STM, and the development of a substrate/coating system which would allow complementary TEM information to be obtained for films and biological molecules. The authors demonstrate in this paper that ion-beam sputtered iridium on highly ordered pyrolytic graphite (HOPG) has met both these goals. The ion-beam sputtered iridium produced a very fine grained (< 10 {angstrom}) continuous film at 5--6 {angstrom} thickness suitable for stable air STM imaging. In comparison, cathode sputtered platinum produced 16 {angstrom} grains with the thinnest continuous film at 15 {angstrom} thickness, and the sputtered gold/palladium produced 25 {angstrom} grains with the thinnest continuous film at 18 {angstrom} thickness.

  16. Stepwise crystallization and the layered distribution in crystallization kinetics of ultra-thin poly(ethylene terephthalate) film

    Energy Technology Data Exchange (ETDEWEB)

    Zuo, Biao, E-mail: chemizuo@zstu.edu.cn, E-mail: wxinping@yahoo.com; Xu, Jianquan; Sun, Shuzheng; Liu, Yue; Yang, Juping; Zhang, Li; Wang, Xinping, E-mail: chemizuo@zstu.edu.cn, E-mail: wxinping@yahoo.com [Department of Chemistry, Key Laboratory of Advanced Textile Materials and Manufacturing Technology of the Education Ministry, Zhejiang Sci-Tech University, Hangzhou 310018 (China)

    2016-06-21

    Crystallization is an important property of polymeric materials. In conventional viewpoint, the transformation of disordered chains into crystals is usually a spatially homogeneous process (i.e., it occurs simultaneously throughout the sample), that is, the crystallization rate at each local position within the sample is almost the same. Here, we show that crystallization of ultra-thin poly(ethylene terephthalate) (PET) films can occur in the heterogeneous way, exhibiting a stepwise crystallization process. We found that the layered distribution of glass transition dynamics of thin film modifies the corresponding crystallization behavior, giving rise to the layered distribution of the crystallization kinetics of PET films, with an 11-nm-thick surface layer having faster crystallization rate and the underlying layer showing bulk-like behavior. The layered distribution in crystallization kinetics results in a particular stepwise crystallization behavior during heating the sample, with the two cold-crystallization temperatures separated by up to 20 K. Meanwhile, interfacial interaction is crucial for the occurrence of the heterogeneous crystallization, as the thin film crystallizes simultaneously if the interfacial interaction is relatively strong. We anticipate that this mechanism of stepwise crystallization of thin polymeric films will allow new insight into the chain organization in confined environments and permit independent manipulation of localized properties of nanomaterials.

  17. XPS and angle resolved XPS, in the semiconductor industry: Characterization and metrology control of ultra-thin films

    International Nuclear Information System (INIS)

    Brundle, C.R.; Conti, Giuseppina; Mack, Paul

    2010-01-01

    This review discusses the development of X-ray photoelectron spectroscopy, XPS, used as a characterization and metrology method for ultra-thin films in the semiconductor wafer processing industry. After a brief explanation of how the relative roles of XPS and Auger electron spectroscopy, AES, have changed over the last 15 years or so in the semiconductor industry, we go into some detail as to what is implied by metrology, as opposed to characterization, for thin films in the industry, and then describe how XPS, and particularly angle resolved XPS, ARXPS, have been implemented as a metrology 'tool' for thickness, chemical composition, and non-destructive depth profiling, of transistor gate oxide material, a key requirement in front-end processing. We take a historical approach, dealing first with the early use for SiO 2 films on Si(1 0 0), then moving to silicon oxynitride, SiO x N y in detail, and finally and briefly HfO 2 -based material, which is used today in the most advanced devices (32 nm node).

  18. Flexible Mixed-Potential-Type (MPT NO2 Sensor Based on An Ultra-Thin Ceramic Film

    Directory of Open Access Journals (Sweden)

    Rui You

    2017-07-01

    Full Text Available A novel flexible mixed-potential-type (MPT sensor was designed and fabricated for NO2 detection from 0 to 500 ppm at 200 °C. An ultra-thin Y2O3-doped ZrO2 (YSZ ceramic film 20 µm thick was sandwiched between a heating electrode and reference/sensing electrodes. The heating electrode was fabricated by a conventional lift-off process, while the porous reference and the sensing electrodes were fabricated by a two-step patterning method using shadow masks. The sensor’s sensitivity is achieved as 58.4 mV/decade at the working temperature of 200 °C, as well as a detection limit of 26.7 ppm and small response time of less than 10 s at 200 ppm. Additionally, the flexible MPT sensor demonstrates superior mechanical stability after bending over 50 times due to the mechanical stability of the YSZ ceramic film. This simply structured, but highly reliable flexible MPT NO2 sensor may lead to wide application in the automobile industry for vehicle emission systems to reduce NO2 emissions and improve fuel efficiency.

  19. General method for simultaneous optimization of light trapping and carrier collection in an ultra-thin film organic photovoltaic cell

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Cheng-Chia, E-mail: ct2443@columbia.edu; Grote, Richard R.; Beck, Jonathan H.; Kymissis, Ioannis [Department of Electrical Engineering, Columbia University, New York, New York 10027 (United States); Osgood, Richard M. [Department of Electrical Engineering, Columbia University, New York, New York 10027 (United States); Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States); Englund, Dirk [Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2014-07-14

    We describe a general method for maximizing the short-circuit current in thin planar organic photovoltaic (OPV) heterojunction cells by simultaneous optimization of light absorption and carrier collection. Based on the experimentally obtained complex refractive indices of the OPV materials and the thickness-dependence of the internal quantum efficiency of the OPV active layer, we analyze the potential benefits of light trapping strategies for maximizing the overall power conversion efficiency of the cell. This approach provides a general strategy for optimizing the power conversion efficiency of a wide range of OPV structures. In particular, as an experimental trial system, the approach is applied here to a ultra-thin film solar cell with a SubPc/C{sub 60} photovoltaic structure. Using a patterned indium tin oxide (ITO) top contact, the numerically optimized designs achieve short-circuit currents of 0.790 and 0.980 mA/cm{sup 2} for 30 nm and 45 nm SubPc/C{sub 60} heterojunction layer thicknesses, respectively. These values correspond to a power conversion efficiency enhancement of 78% for the 30 nm thick cell, but only of 32% for a 45 nm thick cell, for which the overall photocurrent is actually higher. Applied to other material systems, the general optimization method can elucidate if light trapping strategies can improve a given cell architecture.

  20. Logic circuits composed of flexible carbon nanotube thin-film transistor and ultra-thin polymer gate dielectric

    Science.gov (United States)

    Lee, Dongil; Yoon, Jinsu; Lee, Juhee; Lee, Byung-Hyun; Seol, Myeong-Lok; Bae, Hagyoul; Jeon, Seung-Bae; Seong, Hyejeong; Im, Sung Gap; Choi, Sung-Jin; Choi, Yang-Kyu

    2016-05-01

    Printing electronics has become increasingly prominent in the field of electronic engineering because this method is highly efficient at producing flexible, low-cost and large-scale thin-film transistors. However, TFTs are typically constructed with rigid insulating layers consisting of oxides and nitrides that are brittle and require high processing temperatures, which can cause a number of problems when used in printed flexible TFTs. In this study, we address these issues and demonstrate a method of producing inkjet-printed TFTs that include an ultra-thin polymeric dielectric layer produced by initiated chemical vapor deposition (iCVD) at room temperature and highly purified 99.9% semiconducting carbon nanotubes. Our integrated approach enables the production of flexible logic circuits consisting of CNT-TFTs on a polyethersulfone (PES) substrate that have a high mobility (up to 9.76 cm2 V-1 sec-1), a low operating voltage (less than 4 V), a high current on/off ratio (3 × 104), and a total device yield of 90%. Thus, it should be emphasized that this study delineates a guideline for the feasibility of producing flexible CNT-TFT logic circuits with high performance based on a low-cost and simple fabrication process.

  1. Discharge amplified photo-emission from ultra-thin films applied to tuning work function of transparent electrodes in organic opto-electronic devices

    International Nuclear Information System (INIS)

    Gentle, A.R.; Smith, G.B.; Watkins, S.E.

    2013-01-01

    A novel photoemission technique utilising localised discharge amplification of photo-yield is reported. It enables fast, accurate measurement of work function and ionisation potential for ultra-thin buffer layers vacuum deposited onto single and multilayer transparent conducting electrodes for organic solar cells and OLED's. Work function in most traditional transparent electrodes has to be raised to maximise charge transfer while high transmittance and high conductance must be retained. Results are presented for a range of metal oxide buffers, which achieve this goal. This compact photo-yield spectroscopy tool with its fast turn-around has been a valuable development aid since ionisation potential can vary significantly as deposition conditions change slightly, and as ultra-thin films grow. It has also been useful in tracking the impact of different post deposition cleaning treatments along with some storage and transport protocols, which can adversely reduce ionisation potential and hence subsequent device performance.

  2. Preparation and characterization of ultra-thin sol-gel films

    International Nuclear Information System (INIS)

    Shapiro, Leora; Marx, Sharon; Mandler, Daniel

    2007-01-01

    The formation and characterization of nanometer thick sol-gel films are reported. The films were prepared by spin-coating of a diluted solution of a silane precursor on a number of different substrates. The effect of dilution, rotation speed and nature of substrate on the thickness and homogeneity of the films was examined. Characterization of the films was carried out by profilometry, reflectance spectroscopy, atomic force microscopy, adhesion test and electrochemistry. We find that the dilution factor has a pronounced effect on the film thickness. Moreover, the time of dilution, namely, whether dilution was carried out before or after a period of hydrolysis, has a noticeable effect on the thickness as well as on the permeability of embedded species

  3. Robust ultra-thin RuMo alloy film as a seedless Cu diffusion barrier

    International Nuclear Information System (INIS)

    Hsu, Kuo-Chung; Perng, Dung-Ching; Wang, Yi-Chun

    2012-01-01

    Highlights: ► A 5 nm-thick Mo added Ru film has been investigated as a Cu diffusion barrier layer. ► RuMo film provides over 175 °C improvement in thermal stability than that of pure Ru layer. ► The 5 nm-thick RuMo film shows excellent barrier performance against Cu diffusion upon 725 °C. - Abstract: This study investigated the properties of 5 nm-thick RuMo film as a Cu diffusion barrier. The sheet resistance variation and X-ray diffraction patterns show that the RuMo alloy film has excellent barrier performance and that it is stable upon annealing at 725 °C against Cu. The transmission electron microscopy micrograph and diffraction patterns show that the RuMo film is an amorphous-like structure, whereas pure Ru film is a nano-crystalline structure. The elements’ depth profiles, analyzed by X-ray photoelectron spectroscopy, indicate no inter-diffusion behavior between the Cu and Si layer, even annealing at 700 °C. Lower leakage current has been achieved from the Cu/barrier/insulator/Si test structure using RuMo film as the barrier layer. A 5 nm ultrathin RuMo film provided two orders of magnitude improvement in leakage current and also exhibited a 175 °C improvement in thermal stability than that of the pure Ru film. It is a potential candidate as a seedless Cu diffusion barrier for advanced Cu interconnects.

  4. Oxygen-enabled control of Dzyaloshinskii-Moriya Interaction in ultra-thin magnetic films

    KAUST Repository

    Belabbes, Abderrezak; Bihlmayer, Gustav; Blü gel, Stefan; Manchon, Aurelien

    2016-01-01

    ferromagnets, resulting in spin spirals and nanoskyrmion lattices. Here, using relativistic first-principles calculations, we demonstrate that the magnitude and sign of DMI can be entirely controlled by tuning the oxygen coverage of the magnetic film, therefore

  5. In situ X-ray synchrotron study of organic semiconductor ultra-thin films growth

    International Nuclear Information System (INIS)

    Moulin, J.-F.; Dinelli, F.; Massi, M.; Albonetti, C.; Kshirsagar, R.; Biscarini, F.

    2006-01-01

    In this work we present an X-ray diffraction study of the early stages of growth of an organic semiconductor (sexithiophene, T 6 ) thin film prepared by high vacuum sublimation. Specular reflectometry and grazing incidence X-ray diffraction were used to monitor the formation of T 6 films on silicon oxide. Our results show that T 6 grows as a crystalline layer from the beginning of the evaporation. The reflectometry analysis suggests that, in the range of rates and temperatures studied, the growth is never layer by layer but rather 3D in nature. In-plane GIXD has allowed us to observe for the first time a thin film phase of T 6 formed of molecules standing normal to the substrate and arranged in a compressed unit cell with respect to the bulk, i.e. the unit cell parameters b and c are relatively smaller. We have followed the dynamics of formation of this new phase and identified the threshold of appearance of the bulk phase, which occurs above ∼5-6 monolayers. These results are relevant to the problem of organic thin film transistors, for which we have previously demonstrated experimentally that only the first two monolayers of T 6 films are involved in the electrical transport. The layers above the second one do not effectively contribute to charge mobility, either because they are more 'disordered' or because of a screening of the gate field

  6. Indigenous unit for bending and twisting tests of ultra-thin films on a flexible substrate

    Science.gov (United States)

    D'souza, Slavia Deeksha; Hazarika, Pratim; Prakasarao, Ch Surya; Kovendhan, M.; Kumar, R. Arockia; Joseph, D. Paul

    2018-04-01

    An indigenous unit is designed to test the stability of thin films deposited on to a flexible substrate by inducing a required number of bending and twisting under specific conditions. The unit is designed using aluminum and automated by sending pulse width modulated signals to servo motors using ATmega328 microcontroller. We have tested the unit by imparting stress on to a commercial ITO film deposited on a PET substrate. After a definite number of bending and twisting cycles, the electrical and surface properties are studied and the results are discussed.

  7. Morphology and N₂ Permeance of Sputtered Pd-Ag Ultra-Thin Film Membranes.

    Science.gov (United States)

    Fernandez, Ekain; Sanchez-Garcia, Jose Angel; Viviente, Jose Luis; van Sint Annaland, Martin; Gallucci, Fausto; Tanaka, David A Pacheco

    2016-02-10

    The influence of the temperature during the growth of Pd-Ag films by PVD magnetron sputtering onto polished silicon wafers was studied in order to avoid the effect of the support roughness on the layer growth. The surfaces of the Pd-Ag membrane films were analyzed by atomic force microscopy (AFM), and the results indicate an increase of the grain size from 120 to 250-270 nm and film surface roughness from 4-5 to 10-12 nm when increasing the temperature from around 360-510 K. After selecting the conditions for obtaining the smallest grain size onto silicon wafer, thin Pd-Ag (0.5-2-µm thick) films were deposited onto different types of porous supports to study the influence of the porous support, layer thickness and target power on the selective layer microstructure and membrane properties. The Pd-Ag layers deposited onto ZrO₂ 3-nm top layer supports (smallest pore size among all tested) present high N₂ permeance in the order of 10(-6) mol·m(-2)·s(-1)·Pa(-1) at room temperature.

  8. Morphology and N2 Permeance of Sputtered Pd-Ag Ultra-Thin Film Membranes

    Directory of Open Access Journals (Sweden)

    Ekain Fernandez

    2016-02-01

    Full Text Available The influence of the temperature during the growth of Pd-Ag films by PVD magnetron sputtering onto polished silicon wafers was studied in order to avoid the effect of the support roughness on the layer growth. The surfaces of the Pd-Ag membrane films were analyzed by atomic force microscopy (AFM, and the results indicate an increase of the grain size from 120 to 250–270 nm and film surface roughness from 4–5 to 10–12 nm when increasing the temperature from around 360–510 K. After selecting the conditions for obtaining the smallest grain size onto silicon wafer, thin Pd-Ag (0.5–2-µm thick films were deposited onto different types of porous supports to study the influence of the porous support, layer thickness and target power on the selective layer microstructure and membrane properties. The Pd-Ag layers deposited onto ZrO2 3-nm top layer supports (smallest pore size among all tested present high N2 permeance in the order of 10−6 mol·m−2·s−1·Pa−1 at room temperature.

  9. Deposition and properties of cobalt- and ruthenium-based ultra-thin films

    Science.gov (United States)

    Henderson, Lucas Benjamin

    Future copper interconnect systems will require replacement of the materials that currently comprise both the liner layer(s) and the capping layer. Ruthenium has previously been considered as a material that could function as a single material liner, however its poor ability to prevent copper diffusion makes it incompatible with liner requirements. A recently described chemical vapor deposition route to amorphous ruthenium-phosphorus alloy films could correct this problem by eliminating the grain boundaries found in pure ruthenium films. Bias-temperature stressing of capacitor structures using 5 nm ruthenium-phosphorus film as a barrier to copper diffusion and analysis of the times-to-failure at accelerated temperature and field conditions implies that ruthenium-phosphorus performs acceptably as a diffusion barrier for temperatures above 165°C. The future problems associated with the copper capping layer are primarily due to the poor adhesion between copper and the current Si-based capping layers. Cobalt, which adheres well to copper, has been widely proposed to replace the Si-based materials, but its ability to prevent copper diffusion must be improved if it is to be successfully implemented in the interconnect. Using a dual-source chemistry of dicobaltoctacarbonyl and trimethylphosphine at temperatures from 250-350°C, amorphous cobalt-phosphorus can be deposited by chemical vapor deposition. The films contain elemental cobalt and phosphorus, plus some carbon impurity, which is incorporated in the film as both graphitic and carbidic (bonded to cobalt) carbon. When deposited on copper, the adhesion between the two materials remains strong despite the presence of phosphorus and carbon at the interface, but the selectivity for growth on copper compared to silicon dioxide is poor and must be improved prior to consideration for application in interconnect systems. A single molecule precursor containing both cobalt and phosphorus atoms, tetrakis

  10. Writing on ultra thin uniaxially oriented polymer films with an electron beam

    International Nuclear Information System (INIS)

    Petermann, J.; Wenderoth, K.

    1990-01-01

    Information storage polymers have been described and used for many years. When using an electron beam to store information, chemical changes in the macromolecules via local radiation damage is utilized to print the information into the polymer. This letter reports the writing of optically detectable information into birefringent polymer films. The method is based on the fact that preferred orientation of the macromolecules can be destroyed by electron radiation damage. The damage is produced by an electron beam in a transmission electron microscope. The resulting information is observed optically in a polarizing microscope. The polymer films used in the present study were polybutene 1 (PB 1), polyethylene (PE) and polyvinyl-idenfluoride (PVDF). (author)

  11. Experimental study of ultra-thin films mechanical integrity by combined nanoindentation and nano-acoustic emission

    Science.gov (United States)

    Zhang, Zihou

    Advancement of interconnect technology has imposed significant challenge on interface characterization and reliability for blurred interfaces between layers. There is a need for material properties and these miniaturized length scales and assessment of reliability; including the intrinsic film fracture toughness and the interfacial fracture toughness. The nano-meter range of film thicknesses currently employed, impose significant challenges on evaluating these physical quantities and thereby impose significant challenge on the design cycle. In this study we attempted to use a combined nano-indentation and nano-acoustic emission to qualitatively and quantitatively characterize the failure modes in ultra-thin blanket films on Si substrates or stakes of different characteristics. We have performed and analyzed an exhaustive group of testes that cove many diverge combination of film-substrate combination, provided by both Intel and IBM. When the force-indentation depth curve shows excursion, a direct measure of the total energy release rate is estimated. The collected acoustic emission signal is then used to partition the total energy into two segments, one associated with the cohesive fracture toughness of the film and the other is for the adhesive fracture toughness of the interface. The acoustic emission signal is analyzed in both the time and frequency domain to achieve such energy division. In particular, the signal time domain analysis for signal skewness, time of arrival and total energy content are employed with the proper signal to noise ratio. In the frequency domain, an expansive group of acoustic emission signals are utilized to construct the details of the power spectral density. A bank of band-pass filters are designed to sort the individual signals to those associated with adhesive interlayer cracking, cohesive channel cracking, or other system induced noise. The attenuation time and the energy content within each spectral frequency were the key elements

  12. Epitaxial growth of ultra-thin NbN films on AlxGa1−xN buffer-layers

    International Nuclear Information System (INIS)

    Krause, S; Meledin, D; Desmaris, V; Pavolotsky, A; Belitsky, V; Rudziński, M; Pippel, E

    2014-01-01

    The suitability of Al x Ga 1−x N epilayers to deposit onto ultra-thin NbN films has been demonstrated for the first time. High quality single-crystal films with 5 nm thickness confirmed by high resolution transmission electron microscopy (HRTEM) have been deposited in a reproducible manner by means of reactive DC magnetron sputtering at elevated temperatures and exhibit critical temperatures (T c ) as high as 13.2 K and residual resistivity ratio (RRR) ∼1 on hexagonal GaN epilayers. On increasing the Al content x in the Al x Ga 1−x N epilayer above 20%, a gradual deterioration of T c to 10 K was observed. Deposition of NbN on bare silicon substrates served as a reference and comparison. Excellent spatial homogeneity of the fabricated films was confirmed by R(T) measurements of patterned micro-bridges across the entire film area. The superconducting properties of these films were further characterized by critical magnetic field and critical current measurements. It is expected that the employment of GaN material as a buffer-layer for the deposition of ultra-thin NbN films will prospectively benefit terahertz electronics, particularly hot electron bolometer (HEB) mixers. (paper)

  13. Facing-target sputtering deposition of ZnO films with Pt ultra-thin layers for gas-phase photocatalytic application

    International Nuclear Information System (INIS)

    Zhang Zhonghai; Hossain, Md. Faruk.; Arakawa, Takuya; Takahashi, Takakazu

    2010-01-01

    In this paper, various zinc oxide (ZnO) films are deposited by a versatile and effective dc-reactive facing-target sputtering method. The ratios of Ar to O 2 in the mixture gas are varied from 8:2 to 6:4 at a fixed sputtering pressure of 1.0 Pa. X-ray diffraction, spectrophotometer and scanning electron microscope are used to study the crystal structure, optical property and surface morphology of the as-deposited films. The Pt ultra-thin layer, ∼2 nm thick, is deposited on the surface of ZnO film by dc diode sputtering with a mesh mask controlling the coated area. The photocatalytic activity of ZnO films and Pt-ZnO films is evaluated by decomposition of methanol under UV-vis light irradiation. The variation of photocatalytic activity depends on the ratios of Ar to O 2 , which is mainly attributed to the different grain size and carrier mobility. Though the pure ZnO film normally shows a low gas-phase photocatalytic activity, its activity is significantly enhanced by depositing Pt ultra-thin layer.

  14. Atomic layer deposition assisted pattern transfer technology for ultra-thin block copolymer films

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Wenhui; Luo, Jun; Meng, Lingkuan; Li, Junjie; Xiang, Jinjuan; Li, Junfeng; Wang, Wenwu; Chen, Dapeng; Ye, Tianchun; Zhao, Chao

    2016-08-31

    As an emerging developing technique for next-generation lithography, directed self-assembly (DSA) of block copolymer (BCP) has attracted numerous attention and has been a potential alternative to supplement the intrinsic limitations of conventional photolithography. In this work, the self-assembling properties of a lamellar diblock copolymer poly(styrene-b-methylmethacrylate) (PS-b-PMMA, 22k-b-22k, L{sub 0} = 25 nm) on Si substrate and an atomic layer deposition (ALD)-assisted pattern transfer technology for the application of DSA beyond 16/14 nm complementary metal oxide semiconductor (CMOS) technology nodes, were investigated. Firstly, two key processing parameters of DSA, i.e. annealing temperatures and durations of BCP films, were optimized to achieve low defect density and high productivity. After phase separation of BCP films, self-assembling patterns of low defect density should be transferred to the substrate. However, due to the nano-scale thickness and the weak resistance of BCP films to dry etching, it is nearly impossible to transfer the BCP patterns directly to the substrate. Therefore, an ALD-based technology was explored in this work, in which deposited Al{sub 2}O{sub 3} selectively reacts with PMMA blocks thus hardening the PMMA patterns. After removing PS blocks by plasma etching, hardened PMMA patterns were left and transferred to underneath SiO{sub 2} hard mask layer. Using this patterned hard mask, nanowire array of 25 nm pitch were realized on Si substrate. From this work, a high-throughput DSA baseline flow and related ALD-assisted pattern transfer technique were developed and proved to have good capability with the mainstream CMOS technology. - Highlights: • Optimization on self-assembly process for high productivity and low defectivity • Enhancement of etching ratio and resistance by atomic layer deposition (ALD) • A hard mask was used for pattern quality improvement and contamination control.

  15. Thermal conductivity of ultra-thin chemical vapor deposited hexagonal boron nitride films

    International Nuclear Information System (INIS)

    Alam, M. T.; Haque, M. A.; Bresnehan, M. S.; Robinson, J. A.

    2014-01-01

    Thermal conductivity of freestanding 10 nm and 20 nm thick chemical vapor deposited hexagonal boron nitride films was measured using both steady state and transient techniques. The measured value for both thicknesses, about 100 ± 10 W m −1 K −1 , is lower than the bulk basal plane value (390 W m −1 K −1 ) due to the imperfections in the specimen microstructure. Impressively, this value is still 100 times higher than conventional dielectrics. Considering scalability and ease of integration, hexagonal boron nitride grown over large area is an excellent candidate for thermal management in two dimensional materials-based nanoelectronics

  16. Emergence of magnetic order in ultra-thin pyrochlore iridate films

    Science.gov (United States)

    Cheema, Suraj; Serrao, Claudy; Mundy, Julia; Patankar, Shreyas; Birgeneau, Robert; Orenstein, Joseph; Salahuddin, Sayeef; Ramesh, Ramamoorthy

    We report on thickness-dependent magnetotransport in (111) - oriented Pb2Ir2O7-x (Pb227) epitaxial thin films. For thicknesses greater than 4 nm, the magnetoresistance (MR) of metallic Pb227 is positive, linear and non-saturated up to 14 T. Meanwhile at 4 nm, the conduction turns nonmetallic and the MR becomes negative and asymmetric upon field-cooling; such traits are reminiscent of all-in-all-out (AIAO) magnetic order in the insulating pyrochlore iridates. Hysteretic low-field MR dips and trained-untrained resistivity bifurcations suggest the presence of magnetic conducting domain walls within the chiral AIAO spin structure. Beyond just AIAO order, angular-dependent MR indicates a magnetic phase space hosting 2-in-2-out (2I2O) spin ice order. Such anomalous magnetotransport calls for re-evaluation of the pyrochlore iridate phase diagram, as epitaxially strained Pb227 exhibits traits reminiscent of both the insulating magnetic and metallic spin-liquid members. Furthermore, these results open avenues for realizing topological phase predictions in (111) - oriented pyrochlore slabs of kagome-triangular iridate heterostructures. This work is supported by the Office of Basic Energy Sciences of the US Department of Energy under Contract No. DE-AC02-05CH11231.

  17. Influence of Oxygen Concentration on the Performance of Ultra-Thin RF Magnetron Sputter Deposited Indium Tin Oxide Films as a Top Electrode for Photovoltaic Devices

    Directory of Open Access Journals (Sweden)

    Jephias Gwamuri

    2016-01-01

    Full Text Available The opportunity for substantial efficiency enhancements of thin film hydrogenated amorphous silicon (a-Si:H solar photovoltaic (PV cells using plasmonic absorbers requires ultra-thin transparent conducting oxide top electrodes with low resistivity and high transmittances in the visible range of the electromagnetic spectrum. Fabricating ultra-thin indium tin oxide (ITO films (sub-50 nm using conventional methods has presented a number of challenges; however, a novel method involving chemical shaving of thicker (greater than 80 nm RF sputter deposited high-quality ITO films has been demonstrated. This study investigates the effect of oxygen concentration on the etch rates of RF sputter deposited ITO films to provide a detailed understanding of the interaction of all critical experimental parameters to help create even thinner layers to allow for more finely tune plasmonic resonances. ITO films were deposited on silicon substrates with a 98-nm, thermally grown oxide using RF magnetron sputtering with oxygen concentrations of 0, 0.4 and 1.0 sccm and annealed at 300 °C air ambient. Then the films were etched using a combination of water and hydrochloric and nitric acids for 1, 3, 5 and 8 min at room temperature. In-between each etching process cycle, the films were characterized by X-ray diffraction, atomic force microscopy, Raman Spectroscopy, 4-point probe (electrical conductivity, and variable angle spectroscopic ellipsometry. All the films were polycrystalline in nature and highly oriented along the (222 reflection. Ultra-thin ITO films with record low resistivity values (as low as 5.83 × 10−4 Ω·cm were obtained and high optical transparency is exhibited in the 300–1000 nm wavelength region for all the ITO films. The etch rate, preferred crystal lattice growth plane, d-spacing and lattice distortion were also observed to be highly dependent on the nature of growth environment for RF sputter deposited ITO films. The structural, electrical

  18. Fabrication and stability investigation of ultra-thin transparent and flexible Cu-Ag-Au tri-layer film on PET

    Science.gov (United States)

    Prakasarao, Ch Surya; D'souza, Slavia Deeksha; Hazarika, Pratim; Karthiselva N., S.; Ramesh Babu, R.; Kovendhan, M.; Kumar, R. Arockia; Joseph, D. Paul

    2018-04-01

    The need for transparent conducting electrodes with high transmittance, low sheet resistance and flexibility to replace Indium Tin Oxide is ever growing. We have deposited and studied the performance of ultra-thin Cu-Ag-Au tri-layer films over a flexible poly-ethylene terephthalate substrate. Scotch tape test showed good adhesion of the metallic film. Transmittance of the tri-layer was around 40 % in visible region. Optical profiler measurements were done to study the surface features. The XRD pattern revealed that film was amorphous. Sheet resistance measured by four probe technique was around 7.7 Ohm/Δ and was stable up to 423 K. The transport parameters by Hall effect showed high conductivity and carrier concentration with a mobility of 5.58 cm2/Vs. Tests performed in an indigenously designed bending unit indicated the films to be stable both mechanically and electrically even after 50,000 bending cycles.

  19. Foldover, quasi-periodicity, spin-wave instabilities in ultra-thin films subject to RF fields

    Energy Technology Data Exchange (ETDEWEB)

    D' Aquino, M. [Department of Electrical Engineering, University of Napoli ' Federico II' , Naples I-80125 (Italy)]. E-mail: mdaquino@unina.it; Bertotti, G. [Istituto Nazionale di Ricerca Metrologica (INRIM), I-10135 Turin (Italy); Serpico, C. [Department of Electrical Engineering, University of Napoli ' Federico II' , Naples I-80125 (Italy); Mayergoyz, I.D. [ECE Department and UMIACS, University of Maryland, College Park, MD 20742 (United States); Bonin, R. [Istituto Nazionale di Ricerca Metrologica (INRIM), I-10135 Turin (Italy); Guida, G. [Department of Electrical Engineering, University of Napoli ' Federico II' , Naples I-80125 (Italy)

    2007-09-15

    We study magnetization dynamics in a uniaxial ultra-thin ferromagnetic disk subject to spatially uniform microwave external fields. The rotational invariance of the system is such that the only admissible spatially uniform steady states are periodic (P-modes) and quasi-periodic (Q-modes) modes. The stability of P-modes versus spatially uniform and nonuniform perturbations is studied by using spin-wave analysis and the instability diagram for all possible P-modes is computed. The predictions of the spin-wave analysis are compared with micromagnetic simulations.

  20. Heteroepitaxial growth and surface structure of L1{sub 0}-MnGa(111) ultra-thin films on GaN(0001)

    Energy Technology Data Exchange (ETDEWEB)

    Mandru, Andrada-Oana; Wang, Kangkang; Cooper, Kevin; Ingram, David C.; Smith, Arthur R. [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States); Garcia Diaz, Reyes; Takeuchi, Noboru [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States); Centro de Nanociencias y Nanotecnologia, Universidad Nacional Autónoma de México, Apartado Postal 14, Ensenada Baja California, Codigo Postal 22800 (Mexico); Haider, Muhammad [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States); Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran, 31261 (Saudi Arabia)

    2013-10-14

    L1{sub 0}-structured MnGa(111) ultra-thin films were heteroepitaxially grown on GaN(0001) under lightly Mn-rich conditions using molecular beam epitaxy. Room-temperature scanning tunneling microscopy (STM) investigations reveal smooth terraces and angular step edges, with the surface structure consisting primarily of a 2 × 2 reconstruction along with small patches of 1 × 2. Theoretical calculations were carried out using density functional theory, and the simulated STM images were calculated using the Tersoff-Hamman approximation, revealing that a stoichiometric 1 × 2 and a Mn-rich 2 × 2 surface structure give the best agreement with the observed experimental images.

  1. Ion-beam mixed ultra-thin cobalt suicide (CoSi2) films by cobalt sputtering and rapid thermal annealing

    Science.gov (United States)

    Kal, S.; Kasko, I.; Ryssel, H.

    1995-10-01

    The influence of ion-beam mixing on ultra-thin cobalt silicide (CoSi2) formation was investigated by characterizing the ion-beam mixed and unmixed CoSi2 films. A Ge+ ion-implantation through the Co film prior to silicidation causes an interface mixing of the cobalt film with the silicon substrate and results in improved silicide-to-silicon interface roughness. Rapid thermal annealing was used to form Ge+ ion mixed and unmixed thin CoSi2 layer from 10 nm sputter deposited Co film. The silicide films were characterized by secondary neutral mass spectroscopy, x-ray diffraction, tunneling electron microscopy (TEM), Rutherford backscattering, and sheet resistance measurements. The experi-mental results indicate that the final rapid thermal annealing temperature should not exceed 800°C for thin (micrographs of the ion-beam mixed and unmixed CoSi2 films reveals that Ge+ ion mixing (45 keV, 1 × 1015 cm-2) produces homogeneous silicide with smooth silicide-to-silicon interface.

  2. Improvement of transistor characteristics and stability for solution-processed ultra-thin high-valence niobium doped zinc-tin oxide thin film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Jeng, Jiann-Shing, E-mail: jsjeng@mail.nutn.edu.tw

    2016-08-15

    Nb-doped Zinc tin oxide (NZTO) channel materials have been prepared by solution process in combination with the spin-coating method. All NZTO thin film transistors (TFTs) are n-type enhancement-mode devices, either without or with Nb additives. High-valence niobium ion (ionic charge = +5) has a larger ionic potential and similar ionic radius to Zn{sup 2+} and Sn{sup 4+} ions. As compared with the pure ZTO device, introducing Nb{sup 5+} ions into the ZTO channel layers can improve the electrical properties and bias stability of TFTs because of the reduction of the oxygen vacancies. This study discusses the connection among the material properties of the NZTO films and the electrical performance and bias stability of NZTO TFTs and how they are influenced by the Nb/(Nb + Sn) molar ratios of NZTO films. - Highlights: • Ultra-thin high-valence niobium doped zinc-tin oxide (NZTO) thin films are prepared using a solution process. • Nb dopants in ZTO films reduce the oxygen vacancy and subgap adsorption of the ZTO films. • The Nb-doping concentration of the NZTO channel layer has a strong influence on the TFT performance.

  3. Preparation of c-axis perpendicularly oriented ultra-thin L10-FePt films on MgO and VN underlayers

    Science.gov (United States)

    Futamoto, Masaaki; Shimizu, Tomoki; Ohtake, Mitsuru

    2018-05-01

    Ultra-thin L10-FePt films of 2 nm average thickness are prepared on (001) oriented MgO and VN underlayers epitaxially grown on base substrate of SrTiO3(001) single crystal. Detailed cross-sectional structures are observed by high-resolution transmission electron microscopy. Continuous L10-FePt(001) thin films with very flat surface are prepared on VN(001) underlayer whereas the films prepared on MgO(001) underlayer consist of isolated L10-FePt(001) crystal islands. Presence of misfit dislocation and lattice bending in L10-FePt material is reducing the effective lattice mismatch with respect to the underlayer to be less than 0.5 %. Formation of very flat and continuous FePt layer on VN underlayer is due to the large surface energy of VN material where de-wetting of FePt material at high temperature annealing process is suppressed under a force balance between the surface and interface energies of FePt and VN materials. An employment of underlayer or substrate material with the lattice constant and the surface energy larger than those of L10-FePt is important for the preparation of very thin FePt epitaxial thin continuous film with the c-axis controlled to be perpendicular to the substrate surface.

  4. Effect of anionic dopants on thickness, morphology and electrical properties of polypyrrole ultra-thin films prepared by in situ chemical polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Mahmoodian, Mehrnoosh [Dep. of Polymer Engineering, Nanostructured Materials Research Center, Sahand University of Technology, Tabriz 51335-1996 (Iran, Islamic Republic of); Pourabbas, Behzad, E-mail: pourabas@sut.ac.ir [Dep. of Polymer Engineering, Nanostructured Materials Research Center, Sahand University of Technology, Tabriz 51335-1996 (Iran, Islamic Republic of); Mohajerzadeh, Shams [Nano-Electronics and Thin Film Lab, School of Electrical and Computer Engineering, University of Tehran, P.O. Box 14395/515, Tehran (Iran, Islamic Republic of)

    2015-05-29

    The effect of different dopant anions on deposition and characteristics of polypyrrole (PPy) thin film has been studied in this work. Ultra-thin films of conducting PPy were deposited on insulating surfaces of glass and oxidized silicon wafer by in situ chemical polymerization in the presence of different anionic dopants including sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, α-naphthalene sulfonic acid, anthraquinone-2-sulfonic acid sodium salt monohydrate/5-sulfosalicylic acid dehydrate, and camphor sulfonic acid. Hydrophilic/hydrophobic properties and morphology of the self-assembled monolayer of N-(3-trimethoxysilylpropyl)pyrrole, the surface modifying agent in this work, and PPy thin films were characterized before and after deposition by contact angle measurements, field emission scanning electron microscopy, and atomic force microscopy. Chemical structure, thickness, and conductivity of the thin films were also studied by attenuated total reflectance Fourier transform infrared spectrometer, ellipsometry, and four-point probe measurements. The results showed deposition of thin films of conducting PPy with comparable thickness in the range of 6-31 nm and different morphologies, uniformity, and smoothness with average roughness in the range of 0.3-6 nm and relatively high range of conductivity on the modified surfaces. - Highlights: • Conducting thin films of polypyrrole were deposited on glass and SiO{sub 2} substrates. • Surface modification using pyrrole-silane was employed prior to polymerization. • Films as thin as ≈ 7 nm were deposited using different surfactant/counter ions. • Chemistry of the counter ion affects thickness, conductivity and morphology. • Lower thickness/higher conductivity were obtained by structurally flexible dopants.

  5. The effects of ultra-thin cerium fluoride film as the anode buffer layer on the electrical characteristics of organic light emitting diodes

    Science.gov (United States)

    Lu, Hsin-Wei; Tsai, Cheng-Che; Hong, Cheng-Shong; Kao, Po-Ching; Juang, Yung-Der; Chu, Sheng-Yuan

    2016-11-01

    In this study, the efficiency of organic light-emitting diodes (OLEDs) was enhanced by depositing a CeF3film as an ultra-thin buffer layer between the indium tin oxide (ITO) electrode and α-naphthylphenylbiphenyldiamine (NPB) hole transport layer, with the structure configuration ITO/CeF3 (0.5, 1, and 1.5 nm)/α-naphthylphenylbiphenyl diamine (NPB) (40 nm)/tris(8-hydroxyquinoline) aluminum (Alq3) (60 nm)/lithium fluoride (LiF) (1 nm)/Al (150 nm). The enhancement mechanism was systematically investigated via several approaches. The X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy results revealed the formation of the UV-ozone treated CeF3 film. The work function increased from 4.8 eV (standard ITO electrode) to 5.22 eV (0.5-nm-thick UV-ozone treated CeF3 film deposited on the ITO electrode). The surface roughness of the UV-ozone treated CeF3 film was smoother than that of the standard ITO electrode. Further, the UV-ozone treated CeF3 film increased both the surface energy and polarity, as determined from contact angle measurements. In addition, admittance spectroscopy measurements showed an increased capacitance and conductance of the OLEDs. Accordingly, the turn-on voltage decreased from 4.2 V to 3.6 V at 1 mA/cm2, the luminance increased from 7588 cd/m2 to 24760 cd/m2, and the current efficiency increased from 3.2 cd/A to 3.8 cd/A when the 0.5-nm-thick UV-ozone treated CeF3 film was inserted into the OLEDs.

  6. Investigation of defects in ultra-thin Al{sub 2}O{sub 3} films deposited on pure copper by the atomic layer deposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Chang, M.L.; Wang, L.C. [Department of Materials Science and Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan (China); Lin, H.C., E-mail: hclinntu@ntu.edu.tw [Department of Materials Science and Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan (China); Chen, M.J., E-mail: mjchen@ntu.edu.tw [Department of Materials Science and Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan (China); Lin, K.M. [Department of Materials Science and Engineering, Feng Chia University, No. 100, Wenhwa Road, Seatwen, Taichung 40724, Taiwan (China)

    2015-12-30

    Graphical abstract: Some residual OH ligands originating from incomplete reaction between TMA and surface species of OH* during ALD process induce the defects in deposited Al{sub 2}O{sub 3} films. Three possible types of defects are suggested. The analytic results indicate the defects are Type-I and/or Type-II but do not directly expose the substrate, like pinholes (Type-III). - Highlights: • Oxidation trials were conducted to investigate the defects in ultra-thin Al{sub 2}O{sub 3} films deposited ALD technique on pure copper. • The residual OH ligands in the deposited Al{sub 2}O{sub 3} films induce looser micro-structure which has worse oxidation resistance. • Superficial contamination particles on substrate surface are confirmed to be one of nucleation sites of the defects. - Abstract: Al{sub 2}O{sub 3} films with various thicknesses were deposited by the atomic layer deposition (ALD) technique on pure copper at temperatures of 100–200 °C. Oxidation trials were conducted in air at 200 °C to investigate the defects in these films. The analytic results show that the defects have a looser micro-structure compared to their surroundings, but do not directly expose the substrate, like pinholes. The film's crystallinity, mechanical properties and oxidation resistance could also be affected by these defects. Superficial contamination particles on the substrate surface are confirmed to be nucleation sites of the defects. A model for the mechanism of defect formation is proposed in this study.

  7. The influence of alloying on the phase formation sequence of ultra-thin nickel silicide films and on the inheritance of texture

    Science.gov (United States)

    Geenen, F. A.; Solano, E.; Jordan-Sweet, J.; Lavoie, C.; Mocuta, C.; Detavernier, C.

    2018-05-01

    The controlled formation of silicide materials is an ongoing challenge to facilitate the electrical contact of Si-based transistors. Due to the ongoing miniaturisation of the transistor, the silicide is trending to ever-thinner thickness's. The corresponding increase in surface-to-volume ratio emphasises the importance of low-energetic interfaces. Intriguingly, the thickness reduction of nickel silicides results in an abrupt change in phase sequence. This paper investigates the sequence of the silicides phases and their preferential orientation with respect to the Si(001) substrate, for both "thin" (i.e., 9 nm) and "ultra-thin" (i.e., 3 nm) Ni films. Furthermore, as the addition of ternary elements is often considered in order to tailor the silicides' properties, additives of Al, Co, and Pt are also included in this study. Our results show that the first silicide formed is epitaxial θ-Ni2Si, regardless of initial thickness or alloyed composition. The transformations towards subsequent silicides are changed through the additive elements, which can be understood through solubility arguments and classical nucleation theory. The crystalline alignment of the formed silicides with the substrate significantly differs through alloying. The observed textures of sequential silicides could be linked through texture inheritance. Our study illustrates the nucleation of a new phase drive to reduce the interfacial energy at the silicide-substrate interface as well as at the interface with the silicide which is being consumed for these sub-10 nm thin films.

  8. Study on characteristics of a double-conductible channel organic thin-film transistor with an ultra-thin hole-blocking layer

    International Nuclear Information System (INIS)

    Guang-Cai, Yuan; Zheng, Xu; Su-Ling, Zhao; Fu-Jun, Zhang; Xue-Yan, Tian; Xu-Rong, Xu; Na, Xu

    2009-01-01

    The properties of top-contact organic thin-film transistors (TC-OTFTs) using ultra-thin 2, 9-dimethyl-4, 7-diphenyl-1, 10-phenanthroline (BCP) as a hole-blocking interlayer have been improved significantly and a BCP interlayer was inserted into the middle of the pentacene active layer. This paper obtains a fire-new transport mode of an OTFT device with double-conductible channels. The accumulation and transfer of the hole carriers are limited by the BCP interlayer in the vertical region of the channel. A huge amount of carriers is located not only at the interface between pentacene and the gate insulator, but also at the two interfaces of pentacene/BCP interlayer and pentacene/gate insulator, respectively. The results suggest that the BCP interlayer may be useful to adjust the hole accumulation and transfer, and can increase the hole mobility and output current of OTFTs. The TC-OTFTs with a BCP interlayer at V DS = −20 V showed excellent hole mobility μFE and threshold voltage V TH of 0.58 cm 2 /(V·s) and −4.6 V, respectively

  9. A study of growth and thermal dewetting behavior of ultra-thin gold films using transmission electron microscopy

    Directory of Open Access Journals (Sweden)

    Sudheer

    2017-07-01

    Full Text Available The growth and solid-state dewetting behavior of Au thin films (0.7 to 8.4 nm deposited on the formvar film (substrate by sputtering technique have been studied using transmission electron microscopy. The size and number density of the Au nanoparticles (NPs change with an increase in the film thickness (0.7 to 2.8 nm. Nearly spherical Au NPs are obtained for 6 nm show capability to be used as an irreversible temperature sensor with a sensitivity of ∼0.1 CAF/°C. It is observed that annealing affects the crystallinity of the Au grains in the films. The electron diffraction measurement also shows annealing induced morphological evolution in the percolated Au thin films (≥3 nm during solid-state dewetting and recrystallization of the grains.

  10. Structure, optical and electrical properties of indium tin oxide ultra thin films prepared by jet nebulizer spray pyrolysis technique

    Directory of Open Access Journals (Sweden)

    M. Thirumoorthi

    2016-03-01

    Full Text Available Indium tin oxide (ITO thin films have been prepared by jet nebulizer spray pyrolysis technique for different Sn concentrations on glass substrates. X-ray diffraction patterns reveal that all the films are polycrystalline of cubic structure with preferentially oriented along (222 plane. SEM images show that films exhibit uniform surface morphology with well-defined spherical particles. The EDX spectrum confirms the presence of In, Sn and O elements in prepared films. AFM result indicates that the surface roughness of the films is reduced as Sn doping. The optical transmittance of ITO thin films is improved from 77% to 87% in visible region and optical band gap is increased from 3.59 to 4.07 eV. Photoluminescence spectra show mainly three emissions peaks (UV, blue and green and a shift observed in UV emission peak. The presence of functional groups and chemical bonding was analyzed by FTIR. Hall effect measurements show prepared films having n-type conductivity with low resistivity (3.9 × 10−4 Ω-cm and high carrier concentrations (6.1 × 1020 cm−3.

  11. Structure analysis of ultra-thin films. STM/AFM. Chousumaku no kozo kaiseki. STM/AFM

    Energy Technology Data Exchange (ETDEWEB)

    Nozoe, H; Yumura, M [National Institute of Materials and Chemical Research, Tsukuba (Japan)

    1994-03-30

    Fullerene (C60) and carbon nanotubes are expected as new carbon structures. This article describes the observation results of C60 and carbon nanotubes by means of STM (scanning tunnel microscope). The STM images of C60 thin films are illustrated, which have been obtained by annealing at 290 centigrade. It was confirmed that C60 monomolecular thin films are formed which conform to the substrate and have high regularity. The step height of C60 monomolecular thin films coincided with the step height of Cu (111) plane, which suggested that the step of films is reflected in that of Cu substrate. For the STM images under bias voltages, various images of C60 with three-fold axis of symmetry were observed. On the other hand, from STM observation of carbon nanotubes with diameter of about 30 nm which were separated and purified from the cathode deposits during the preparation process of C60, it was found that they have concentric multilayer structure. 18 refs., 7 figs.

  12. Temperature dependence of coercive field and fatigue in poly(vinylidene fluoride-trifluoroethylene) copolymer ultra-thin films

    International Nuclear Information System (INIS)

    Zhang Xiuli; Xu Haisheng; Zhang Yanni

    2011-01-01

    The experimental intrinsic coercive field of ferroelectric poly(vinylidene fluoride-trifluoethylene) copolymer films, with both bottom and top gold electrodes is measured at a wide temperature range. In the lower temperature region from -20 to 25 deg. C, the temperature dependence of coercive field shows good agreement with the prediction by the Landau-Ginzburg (LG) mean-field theory. In the higher temperature region from 25 to 80 deg. C, the coercive field shows a slow decrease with the increased temperature, where the LG theory is not applicable any more. The temperature-dependent changes in the polymer chains have been analysed. A reversible 'inherent fatigue' is observed from the partially recovered remanent polarization after re-annealing a fatigued P(VDF-TrFE) film. FTIR spectra indicate that the interchain spacing does not change from 10 to 10 7 switching cycles while the degree of all-trans ferroelectric phase decreases gradually with applied switching cycles. After a re-annealing treatment, ferroelectric phase recovers and dipoles at the boundary of crystallites acquire much higher energy.

  13. Encapsulate-and-peel: fabricating carbon nanotube CMOS integrated circuits in a flexible ultra-thin plastic film.

    Science.gov (United States)

    Gao, Pingqi; Zhang, Qing

    2014-02-14

    Fabrication of single-walled carbon nanotube thin film (SWNT-TF) based integrated circuits (ICs) on soft substrates has been challenging due to several processing-related obstacles, such as printed/transferred SWNT-TF pattern and electrode alignment, electrical pad/channel material/dielectric layer flatness, adherence of the circuits onto the soft substrates etc. Here, we report a new approach that circumvents these challenges by encapsulating pre-formed SWNT-TF-ICs on hard substrates into polyimide (PI) and peeling them off to form flexible ICs on a large scale. The flexible SWNT-TF-ICs show promising performance comparable to those circuits formed on hard substrates. The flexible p- and n-type SWNT-TF transistors have an average mobility of around 60 cm(2) V(-1) s(-1), a subthreshold slope as low as 150 mV dec(-1), operating gate voltages less than 2 V, on/off ratios larger than 10(4) and a switching speed of several kilohertz. The post-transfer technique described here is not only a simple and cost-effective pathway to realize scalable flexible ICs, but also a feasible method to fabricate flexible displays, sensors and solar cells etc.

  14. Formation of Surface and Quantum-Well States in Ultra Thin Pt Films on the Au(111 Surface

    Directory of Open Access Journals (Sweden)

    Igor V. Silkin

    2017-12-01

    Full Text Available The electronic structure of the Pt/Au(111 heterostructures with a number of Pt monolayers n ranging from one to three is studied in the density-functional-theory framework. The calculations demonstrate that the deposition of the Pt atomic thin films on gold substrate results in strong modifications of the electronic structure at the surface. In particular, the Au(111 s-p-type Shockley surface state becomes completely unoccupied at deposition of any number of Pt monolayers. The Pt adlayer generates numerous quantum-well states in various energy gaps of Au(111 with strong spatial confinement at the surface. As a result, strong enhancement in the local density of state at the surface Pt atomic layer in comparison with clean Pt surface is obtained. The excess in the density of states has maximal magnitude in the case of one monolayer Pt adlayer and gradually reduces with increasing number of Pt atomic layers. The spin–orbit coupling produces strong modification of the energy dispersion of the electronic states generated by the Pt adlayer and gives rise to certain quantum states with a characteristic Dirac-cone shape.

  15. Influences of ultra-thin Ti seed layers on the dewetting phenomenon of Au films deposited on Si oxide substrates

    Science.gov (United States)

    Kamiko, Masao; Kim, So-Mang; Jeong, Young-Seok; Ha, Jae-Ho; Koo, Sang-Mo; Ha, Jae-Geun

    2018-05-01

    The influences of a Ti seed layer (1 nm) on the dewetting phenomenon of Au films (5 nm) grown onto amorphous SiO2 substrates have been studied and compared. Atomic force microscopy results indicated that the introduction of Ti between the substrate and Au promoted the dewetting phenomenon. X-ray diffraction measurements suggested that the initial deposition of Ti promoted crystallinity of Au. A series of Auger electron spectroscopy and X-ray photoelectron spectroscopy results revealed that Ti transformed to a Ti oxide layer by reduction of the amorphous SiO2 substrate surface, and that the Ti seed layer remained on the substrate, without going through the dewetting process during annealing. We concluded that the enhancement of Au dewetting and the improvement in crystallinity of Au by the insertion of Ti could be attributed to the fact that Au location was changed from the surface of the amorphous SiO2 substrate to that of the Ti oxide layer.

  16. Encapsulate-and-peel: fabricating carbon nanotube CMOS integrated circuits in a flexible ultra-thin plastic film

    International Nuclear Information System (INIS)

    Gao, Pingqi; Zhang, Qing

    2014-01-01

    Fabrication of single-walled carbon nanotube thin film (SWNT-TF) based integrated circuits (ICs) on soft substrates has been challenging due to several processing-related obstacles, such as printed/transferred SWNT-TF pattern and electrode alignment, electrical pad/channel material/dielectric layer flatness, adherence of the circuits onto the soft substrates etc. Here, we report a new approach that circumvents these challenges by encapsulating pre-formed SWNT-TF-ICs on hard substrates into polyimide (PI) and peeling them off to form flexible ICs on a large scale. The flexible SWNT-TF-ICs show promising performance comparable to those circuits formed on hard substrates. The flexible p- and n-type SWNT-TF transistors have an average mobility of around 60 cm 2  V −1  s −1 , a subthreshold slope as low as 150 mV  dec −1 , operating gate voltages less than 2 V, on/off ratios larger than 10 4 and a switching speed of several kilohertz. The post-transfer technique described here is not only a simple and cost-effective pathway to realize scalable flexible ICs, but also a feasible method to fabricate flexible displays, sensors and solar cells etc. (paper)

  17. The impact of ultra-thin titania interlayers on open circuit voltage and carrier lifetime in thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Moerman, David; Colbert, Adam E.; Ginger, David S., E-mail: ginger@chem.washington.edu [Department of Chemistry, University of Washington, Seattle, Washington 98195 (United States); Kim, Hyungchul; Graham, Samuel, E-mail: sgraham@gatech.edu [School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)

    2016-03-14

    We study the effects of modifying indium tin oxide electrodes with ultrathin titania (TiO{sub 2}) layers grown via plasma-enhanced atomic layer deposition (PE-ALD). We find an optimal thickness of PE-ALD-grown titania by tracking performance, which initially increases, peaks, and eventually decreases with increasing TiO{sub 2} thickness. We use scanning Kelvin probe microscopy (SKPM) to measure both the local work function and its distribution as a function of TiO{sub 2} thickness. We find that the variance in contact potential difference across the surface of the film is related to either the amorphous or anatase TiO{sub 2} form. Finally, we use local SKPM recombination rate experiments, supported by bulk transient photovoltage and charge extraction measurements. We show that the optimum TiO{sub 2} thickness is the one for which the carrier lifetime is the longest and the charge carrier density is the highest, when the TiO{sub 2} is amorphous, in agreement with the device measurements.

  18. The impact of ultra-thin titania interlayers on open circuit voltage and carrier lifetime in thin film solar cells

    International Nuclear Information System (INIS)

    Moerman, David; Colbert, Adam E.; Ginger, David S.; Kim, Hyungchul; Graham, Samuel

    2016-01-01

    We study the effects of modifying indium tin oxide electrodes with ultrathin titania (TiO_2) layers grown via plasma-enhanced atomic layer deposition (PE-ALD). We find an optimal thickness of PE-ALD-grown titania by tracking performance, which initially increases, peaks, and eventually decreases with increasing TiO_2 thickness. We use scanning Kelvin probe microscopy (SKPM) to measure both the local work function and its distribution as a function of TiO_2 thickness. We find that the variance in contact potential difference across the surface of the film is related to either the amorphous or anatase TiO_2 form. Finally, we use local SKPM recombination rate experiments, supported by bulk transient photovoltage and charge extraction measurements. We show that the optimum TiO_2 thickness is the one for which the carrier lifetime is the longest and the charge carrier density is the highest, when the TiO_2 is amorphous, in agreement with the device measurements.

  19. Microstructure and growth kinetics of nickel silicide ultra-thin films synthesized by solid-state reactions

    Science.gov (United States)

    Coia, Cedrik

    The objective of the thesis is to develop a detailed fundamental understanding of the thermally induced solid-state reactions that lead to the formation of the NiSi. We use in situ synchrotron x-ray diffraction as well as wafer curvature measurements to monitor reactions as they occur during the annealing treatment. These analyses are complemented by ex situ transmission electron microscopy, Rutherford backscattering spectroscopy, and secondary ions mass spectroscopy. The solid-state reactions between 4 to 500 nm-thick Ni films and Si (001) are considerably more complex than previously believed. In addition to the commonly observed phases listed above, we observe the formation of three additional compounds---θ-Ni2Si, Ni31Si12 and Ni3Si2---before the complete transformation of the reacted film into NiSi. These compounds are found to co-exist laterally (within the same layer) with delta-Ni2Si and/or NiSi. The metastable compound θ-Ni2Si, which formation results from texture inheritance and rapid growth through vacancy diffusion, is present in all samples and forms at the same temperature (300+/-10°C) regardless of the initial Ni thickness. Indeed, this compound forms rapidly during ramps anneals, apparently consuming all the delta-Ni2Si for initial Ni films thickness of up to 10 nm. Its disappearance is also rapid and is correlated to both the growth of NiSi and to a surprising return of the orthorhombic delta-Ni 2Si. The formation sequence is therefore not monotonic in composition in contrast to what is usually expected in solid-state reactions. An investigation of the effect of alloying elements (Pt and Co) and impurities (B, P, As, F, N) on the Ni-Si reactions enables us to determine that nucleation plays a limiting role in the growth of metastable θ-Ni2Si and that the template provided by delta-Ni2Si is crucial in promoting this nucleation. Furthermore, reactions with amorphized and amorphous substrates indicate that the possibility of epitaxy with the Si

  20. Characterization of nano-powder grown ultra-thin film p-CuO/n-Si hetero-junctions by employing vapour-liquid-solid method for photovoltaic applications

    Energy Technology Data Exchange (ETDEWEB)

    Sultana, Jenifar; Das, Anindita [Centre for Research in Nanoscience and Nanotechnology (CRNN), Kolkata 700098 (India); Das, Avishek [Department of Electronic Science, University of Calcutta, Kolkata 700009 (India); Saha, Nayan Ranjan [Department of Polymer Science and Technology, University of Calcutta, Kolkata 700009 (India); Karmakar, Anupam [Department of Electronic Science, University of Calcutta, Kolkata 700009 (India); Chattopadhyay, Sanatan, E-mail: scelc@caluniv.ac.in [Department of Electronic Science, University of Calcutta, Kolkata 700009 (India)

    2016-08-01

    In this work, the CuO nano-powder has been synthesized by employing chemical bath deposition technique for its subsequent use to grow ultrathin film (20 nm) of p-CuO on n-Si substrate for the fabrication of p-CuO/n-Si hetero-junction diodes. The thin CuO film has been grown by employing vapour-liquid-solid method. The crystalline structure and chemical phase of the film are characterized by employing field-emission scanning electron microscopy and X-ray diffraction studies. Chemical stoichiometry of the film has been confirmed by using energy dispersive X-ray spectroscopy. The potential for photovoltaic applications of such films is investigated by measuring the junction current-voltage characteristics and by extracting the relevant parameters such as open circuit photo-generated voltage, short circuit current density, fill-factor and energy conversion efficiency. - Highlights: • Synthesis of CuO nano-powder by CBD method • Growth of ultra-thin film of CuO by employing VLS method for the first time • Physical and electrical characterization of such films for photovoltaic applications • Estimation of energy conversion efficiency of the p-CuO/n-Si p-n junction solar cell.

  1. 4P-NPD ultra thin-films as efficient exciton blocking layers in DBP/C70 based organic solar cells

    DEFF Research Database (Denmark)

    Patil, Bhushan Ramesh; Liu, Yiming; Qamar, Talha

    2017-01-01

    Exciton blocking effects from ultra thin layers of N,N'-di-1-naphthalenyl-N,N'-diphenyl [1,1':4',1'':4'',1'''-quaterphenyl]-4,4'''-diamine (4P-NPD) was investigated in small molecule based inverted Organic Solar Cells (OSCs) using Tetraphenyldibenzoperiflanthene (DBP) as the electron donor material...... and fullerene (C70) as the electron acceptor material. The short-circuit current density (Jsc) and PCE of the optimized OSCs with 0.7 nm thick 4P-NPD were approx. 16 % and 24 % higher, respectively, compared to reference devices without exciton blocking layers. Drift diffusion based device modeling...... was conducted to model the full Current density – Voltage (JV) characteristics and EQE spectrum of the OSCs, and photoluminescence measurements was conducted to investigate the exciton blocking effects with increasing thicknesses of the 4P-NPD layer. Importantly, coupled optical and electrical modeling studies...

  2. Ultra-thin chip technology and applications

    CERN Document Server

    2010-01-01

    Ultra-thin chips are the "smart skin" of a conventional silicon chip. This book shows how very thin and flexible chips can be fabricated and used in many new applications in microelectronics, microsystems, biomedical and other fields. It provides a comprehensive reference to the fabrication technology, post processing, characterization and the applications of ultra-thin chips.

  3. The Effect of Film Thickness on the Gas Sensing Properties of Ultra-Thin TiO₂ Films Deposited by Atomic Layer Deposition.

    Science.gov (United States)

    Wilson, Rachel L; Simion, Cristian Eugen; Blackman, Christopher S; Carmalt, Claire J; Stanoiu, Adelina; Di Maggio, Francesco; Covington, James A

    2018-03-01

    Analyte sensitivity for gas sensors based on semiconducting metal oxides should be highly dependent on the film thickness, particularly when that thickness is on the order of the Debye length. This thickness dependence has previously been demonstrated for SnO₂ and inferred for TiO₂. In this paper, TiO₂ thin films have been prepared by Atomic Layer Deposition (ALD) using titanium isopropoxide and water as precursors. The deposition process was performed on standard alumina gas sensor platforms and microscope slides (for analysis purposes), at a temperature of 200 °C. The TiO₂ films were exposed to different concentrations of CO, CH₄, NO₂, NH₃ and SO₂ to evaluate their gas sensitivities. These experiments showed that the TiO₂ film thickness played a dominant role within the conduction mechanism and the pattern of response for the electrical resistance towards CH₄ and NH₃ exposure indicated typical n -type semiconducting behavior. The effect of relative humidity on the gas sensitivity has also been demonstrated.

  4. The Effect of Film Thickness on the Gas Sensing Properties of Ultra-Thin TiO2 Films Deposited by Atomic Layer Deposition

    Directory of Open Access Journals (Sweden)

    Rachel L. Wilson

    2018-03-01

    Full Text Available Analyte sensitivity for gas sensors based on semiconducting metal oxides should be highly dependent on the film thickness, particularly when that thickness is on the order of the Debye length. This thickness dependence has previously been demonstrated for SnO2 and inferred for TiO2. In this paper, TiO2 thin films have been prepared by Atomic Layer Deposition (ALD using titanium isopropoxide and water as precursors. The deposition process was performed on standard alumina gas sensor platforms and microscope slides (for analysis purposes, at a temperature of 200 °C. The TiO2 films were exposed to different concentrations of CO, CH4, NO2, NH3 and SO2 to evaluate their gas sensitivities. These experiments showed that the TiO2 film thickness played a dominant role within the conduction mechanism and the pattern of response for the electrical resistance towards CH4 and NH3 exposure indicated typical n-type semiconducting behavior. The effect of relative humidity on the gas sensitivity has also been demonstrated.

  5. Wavelength-tunable colloidal quantum dot laser on ultra-thin flexible glass

    Energy Technology Data Exchange (ETDEWEB)

    Foucher, C.; Guilhabert, B.; Laurand, N.; Dawson, M. D. [Institute of Photonics, SUPA, University of Strathclyde, Glasgow (United Kingdom)

    2014-04-07

    A mechanically flexible and wavelength-tunable laser with an ultra-thin glass membrane as substrate is demonstrated. The optically pumped hybrid device has a distributed feedback cavity that combines a colloidal quantum dot gain film with a grating-patterned polymeric underlayer, all on a 30-μm thick glass sheet. The total thickness of the structure is only 75 μm. The hybrid laser has an average threshold fluence of 450 ± 80 μJ/cm{sup 2} (for 5-ns excitation pulses) at an emitting wavelength of 607 nm. Mechanically bending the thin-glass substrate enables continuous tuning of the laser emission wavelength over an 18-nm range, from 600 nm to 618 nm. The correlation between the wavelength tunability and the mechanical properties of the thin laser structure is verified theoretically and experimentally.

  6. 4P-NPD ultra-thin films as efficient exciton blocking layers in DBP/C70 based organic solar cells

    Science.gov (United States)

    Patil, Bhushan R.; Liu, Yiming; Qamar, Talha; Rubahn, Horst-Günter; Madsen, Morten

    2017-09-01

    Exciton blocking effects from ultra-thin layers of N,N‧-di-1-naphthalenyl-N,N‧-diphenyl [1,1‧:4‧,1″:4″,1‴-quaterphenyl]-4,4‴-diamine (4P-NPD) were investigated in small molecule-based inverted organic solar cells (OSCs) using tetraphenyldibenzoperiflanthene as the electron donor material and fullerene (C70) as the electron acceptor material. The short-circuit current density (J SC) and power conversion efficiency (PCE) of the optimized OSCs with 0.7 nm thick 4P-NPD were approximately 16% and 24% higher, respectively, compared to reference devices without exciton blocking layers (EBLs). Drift diffusion-based device modeling was conducted to model the full current density-voltage (JV) characteristics and external quantum efficiency spectrum of the OSCs, and photoluminescence measurements were conducted to investigate the exciton blocking effects with increasing thicknesses of the 4P-NPD layer. Importantly, coupled optical and electrical modeling studies of the device behaviors and exciton generation rates and densities in the active layer for different 4P-NPD layer thicknesses were conducted, in order to gain a complete understanding of the observed increase in PCE for 4P-NPD layer thicknesses up to 1 nm, and the observed decrease in PCE for layer thicknesses beyond 1 nm. This work demonstrates a route for guiding the integration of EBLs in OSC devices.

  7. Feasibility of Ultra-Thin Fiber-Optic Dosimeters for Radiotherapy Dosimetry.

    Science.gov (United States)

    Lee, Bongsoo; Kwon, Guwon; Shin, Sang Hun; Kim, Jaeseok; Yoo, Wook Jae; Ji, Young Hoon; Jang, Kyoung Won

    2015-11-17

    In this study, prototype ultra-thin fiber-optic dosimeters were fabricated using organic scintillators, wavelength shifting fibers, and plastic optical fibers. The sensor probes of the ultra-thin fiber-optic dosimeters consisted of very thin organic scintillators with thicknesses of 100, 150 and 200 μm. These types of sensors cannot only be used to measure skin or surface doses but also provide depth dose measurements with high spatial resolution. With the ultra-thin fiber-optic dosimeters, surface doses for gamma rays generated from a Co-60 therapy machine were measured. Additionally, percentage depth doses in the build-up regions were obtained by using the ultra-thin fiber-optic dosimeters, and the results were compared with those of external beam therapy films and a conventional fiber-optic dosimeter.

  8. Energy level alignment at the Si(1 1 1)/RCA–SiO2/copper(II) phthalocyanine ultra-thin film interface

    International Nuclear Information System (INIS)

    Krzywiecki, Maciej; Grządziel, Lucyna

    2014-01-01

    Graphical abstract: - Highlights: • The interface formation studies between CuPc and Si by photoemission methods. • Charge rearrangement detected at the inorganic/organic interface. • Existence of disordered/polarization layer at the initial stages of CuPc deposition. • Examined structures applicable for organic transistors development. - Abstract: The photoemission experimental techniques (i.e. ultraviolet photoelectron spectroscopy—UPS and X-ray photoelectron spectroscopy—XPS) were used to investigate the charge–rearrangement–related phenomena occuring at organic–inorganic semiconductor interface. Examined samples were copper phthalocyanine (CuPc) ultra-thin (up to 16 nm) layers deposited onto oxidized silicon Si(1 1 1) of n- and p-type of conductivity. The 1.3-nm-thick silicon oxide was prepared by means of RCA wet cleaning procedure. The analysis of the photoemission data (mainly UPS) suggested the existance of the polarization layer within first 3 nm of CuPc layer thickness. Basing on the UPS and XPS results the energy level diagrams of examined structures have been constructed. In present paper it is suggested that the existance of the polarization layer could be assigned to the disordered adsorption and continous molecular reorientation of the CuPc molecules during the interface formation process. In the terms of the lack of the charge transfer via substrate/organic overlayer interface and disordered adsorption the fluctuations of CuPc electronic parameters were detected. Moreover the ionization energy and the work function parameters of final CuPc layer were affected. The values were more consistent with those obtained for much thicker (over 500 nm) CuPc layers. Performed studies showed that contrary to CuPc layers deposited on native substrates (where the charge transfer via tunnelable oxide – determined as dipole effect – has been detected), the thicker RCA-prepared oxide seems to be non-tunnelable hence the possibility for Si(1 1 1

  9. Ultra-thin Metal and Dielectric Layers for Nanophotonic Applications

    DEFF Research Database (Denmark)

    Shkondin, Evgeniy; Leandro, Lorenzo; Malureanu, Radu

    2015-01-01

    In our talk we first give an overview of the various thin films used in the field of nanophotonics. Then we describe our own activity in fabrication and characterization of ultra-thin films of high quality. We particularly focus on uniform gold layers having thicknesses down to 6 nm fabricated by......-beam deposition on dielectric substrates and Al-oxides/Ti-oxides multilayers prepared by atomic layer deposition in high aspect ratio trenches. In the latter case we show more than 1:20 aspect ratio structures can be achieved....

  10. Ultra thin metallic coatings to control near field radiative heat transfer

    Science.gov (United States)

    Esquivel-Sirvent, R.

    2016-09-01

    We present a theoretical calculation of the changes in the near field radiative heat transfer between two surfaces due to the presence of ultra thin metallic coatings on semiconductors. Depending on the substrates, the radiative heat transfer is modulated by the thickness of the ultra thin film. In particular we consider gold thin films with thicknesses varying from 4 to 20 nm. The ultra-thin film has an insulator-conductor transition close to a critical thickness of dc = 6.4 nm and there is an increase in the near field spectral heat transfer just before the percolation transition. Depending on the substrates (Si or SiC) and the thickness of the metallic coatings we show how the near field heat transfer can be increased or decreased as a function of the metallic coating thickness. The calculations are based on available experimental data for the optical properties of ultrathin coatings.

  11. Ultra-Thin Atomic Layer Deposited TiN Films: Non-Linear I–V Behaviour and the Importance of Surface Passivation

    NARCIS (Netherlands)

    Van Hao, B.; Aarnink, Antonius A.I.; Kovalgin, Alexeij Y.; Wolters, Robertus A.M.

    2011-01-01

    We report the electrical resistivity of atomic layer deposited TiN thin films in the thickness range 2.5-20 nm. The measurements were carried out using the circular transfer length method structures. For the films with thickness in the range of 10-20 nm, the measurements exhibited linear

  12. Enhancement of absorption and color contrast in ultra-thin highly absorbing optical coatings

    Science.gov (United States)

    Kats, Mikhail A.; Byrnes, Steven J.; Blanchard, Romain; Kolle, Mathias; Genevet, Patrice; Aizenberg, Joanna; Capasso, Federico

    2013-09-01

    Recently a new class of optical interference coatings was introduced which comprises ultra-thin, highly absorbing dielectric layers on metal substrates. We show that these lossy coatings can be augmented by an additional transparent subwavelength layer. We fabricated a sample comprising a gold substrate, an ultra-thin film of germanium with a thickness gradient, and several alumina films. The experimental reflectivity spectra showed that the additional alumina layer increases the color range that can be obtained, in agreement with calculations. More generally, this transparent layer can be used to enhance optical absorption, protect against erosion, or as a transparent electrode for optoelectronic devices.

  13. Ultra thin continuously reinforced concrete pavement research in south Africa

    CSIR Research Space (South Africa)

    Perrie, BD

    2007-08-01

    Full Text Available Ultra thin continuously reinforced concrete pavements (UTCRCP), in literature also referred to as Ultra Thin Reinforced High Performance Concrete (UTHRHPC), have been used in Europe successfully as a rehabilitation measure on steel bridge decks...

  14. Ab initio understanding of magnetic properties in Zn2+ substitution of Fe3O4 ultra-thin film with dilute Zn substitution

    Science.gov (United States)

    Huang, Zhaocong; Chen, Qian; Jiang, Sheng; Dong, Shuai; Zhai, Ya

    2018-05-01

    The mechanism of the magnetic properties on the Zn2+ substituted Fe3O4 film have been investigated based on first principle calculations. It is found that the surface effect plays an important role in the occupation of Zn ion, and in turn changes the magnetic moment. It may also destroy the half metallic behavior of Fe3O4 film even if the Zn2+ concentration only is one Zn2+ per unit cell (4%), which is different from that in bulk material.

  15. Growth and characterization of epitaxial ultra-thin NbN films on 3C-SiC/Si substrate for terahertz applications

    International Nuclear Information System (INIS)

    Dochev, D; Desmaris, V; Pavolotsky, A; Meledin, D; Belitsky, V; Lai, Z; Henry, A; Janzen, E; Pippel, E; Woltersdorf, J

    2011-01-01

    We report on electrical properties and microstructure of epitaxial thin NbN films grown on 3C-SiC/Si substrates by means of reactive magnetron sputtering. A complete epitaxial growth at the NbN/3C-SiC interface has been confirmed by means of high resolution transmission electron microscopy (HRTEM) along with x-ray diffractometry (XRD). Resistivity measurements of the films have shown that the superconducting transition onset temperature (T C ) for the best specimen is 11.8 K. Using these epitaxial NbN films, we have fabricated submicron-size hot-electron bolometer (HEB) devices on 3C-SiC/Si substrate and performed their complete DC characterization. The observed critical temperature T C = 11.3 K and critical current density of about 2.5 MA cm -2 at 4.2 K of the submicron-size bridges were uniform across the sample. This suggests that the deposited NbN films possess the necessary homogeneity to sustain reliable hot-electron bolometer device fabrication for THz mixer applications.

  16. Growth and characterization of epitaxial ultra-thin NbN films on 3C-SiC/Si substrate for terahertz applications

    Energy Technology Data Exchange (ETDEWEB)

    Dochev, D; Desmaris, V; Pavolotsky, A; Meledin, D; Belitsky, V [Group for Advanced Receiver Development, Department of Earth and Space Sciences, Chalmers University of Technology, SE-412 96 Gothenburg (Sweden); Lai, Z [Nanofabrication Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE-412 96 Gothenburg (Sweden); Henry, A; Janzen, E [Department of Physics, Chemistry and Biology, Linkoeping University, SE-581 83 Linkoeping (Sweden); Pippel, E; Woltersdorf, J, E-mail: dimitar.dochev@chalmers.se [Max-Planck-Institute of Microstructure Physics, Weinberg 2, D-06120 Halle (Germany)

    2011-03-15

    We report on electrical properties and microstructure of epitaxial thin NbN films grown on 3C-SiC/Si substrates by means of reactive magnetron sputtering. A complete epitaxial growth at the NbN/3C-SiC interface has been confirmed by means of high resolution transmission electron microscopy (HRTEM) along with x-ray diffractometry (XRD). Resistivity measurements of the films have shown that the superconducting transition onset temperature (T{sub C}) for the best specimen is 11.8 K. Using these epitaxial NbN films, we have fabricated submicron-size hot-electron bolometer (HEB) devices on 3C-SiC/Si substrate and performed their complete DC characterization. The observed critical temperature T{sub C} = 11.3 K and critical current density of about 2.5 MA cm{sup -2} at 4.2 K of the submicron-size bridges were uniform across the sample. This suggests that the deposited NbN films possess the necessary homogeneity to sustain reliable hot-electron bolometer device fabrication for THz mixer applications.

  17. Temperature-induced transition of the diffusion mechanism of n-hexane in ultra-thin polystyrene films, resolved by in-situ Spectroscopic Ellipsometry

    NARCIS (Netherlands)

    Ogieglo, Wojciech; Wormeester, Herbert; Wessling, Matthias; Benes, Nieck Edwin

    2013-01-01

    In-situ Spectroscopic Ellipsometry is used to study diffusion of liquid n-hexane in silicon wafer supported 150 nm thick polystyrene films, in the temperature range 16e28 C. In the higher part of this temperature range Case II diffusion is shown to be dominant. In this case the temporal evolution of

  18. Effects of ultraviolet irradiation treatment on low-k SiOC(-H) ultra-thin films deposited by using TMS/O2 PEALD

    International Nuclear Information System (INIS)

    Kim, Changyoung; Woo, Jongkwan; Choi, Chikyu; Navamathavan, R.

    2012-01-01

    We report on the electrical characteristics for the metal-insulator-semiconductor (MIS) structure of low-dielectric-constant SiOC(-H) films. The SiOC(-H) thin films were deposited on p-Si(100) substrates by using a plasma-enhanced atomic layer deposition (PEALD) system. To improve the structural and the electrical characteristics, we post-treated the SiOC(-H) films deposited using PEALD with ultraviolet (UV) irradiation for various time intervals. The radical intensities in the bulk plasma were observed to be influenced strongly by the radio-frequency (rf) power. A complete dissociation of the trimethylsilane (TMS) precursor took place for rf powers greater than 300 W. As the UV treatment time was increased, the bonding structure of the SiOC(-H) film clearly separated to Si-O-Si and Si-O-C bonds. Also, the fixed charge density and the interface state density on the SiOC(-H)/p-Si(100) interface decreased as the UV treatment time was increased to 6 min. Therefore, we were able to minimize the defects and to reduce the interface charge by adjusting the UV dose.

  19. Towards a uniform and large-scale deposition of MoS2 nanosheets via sulfurization of ultra-thin Mo-based solid films.

    Science.gov (United States)

    Vangelista, Silvia; Cinquanta, Eugenio; Martella, Christian; Alia, Mario; Longo, Massimo; Lamperti, Alessio; Mantovan, Roberto; Basset, Francesco Basso; Pezzoli, Fabio; Molle, Alessandro

    2016-04-29

    Large-scale integration of MoS2 in electronic devices requires the development of reliable and cost-effective deposition processes, leading to uniform MoS2 layers on a wafer scale. Here we report on the detailed study of the heterogeneous vapor-solid reaction between a pre-deposited molybdenum solid film and sulfur vapor, thus resulting in a controlled growth of MoS2 films onto SiO2/Si substrates with a tunable thickness and cm(2)-scale uniformity. Based on Raman spectroscopy and photoluminescence, we show that the degree of crystallinity in the MoS2 layers is dictated by the deposition temperature and thickness. In particular, the MoS2 structural disorder observed at low temperature (<750 °C) and low thickness (two layers) evolves to a more ordered crystalline structure at high temperature (1000 °C) and high thickness (four layers). From an atomic force microscopy investigation prior to and after sulfurization, this parametrical dependence is associated with the inherent granularity of the MoS2 nanosheet that is inherited by the pristine morphology of the pre-deposited Mo film. This work paves the way to a closer control of the synthesis of wafer-scale and atomically thin MoS2, potentially extendable to other transition metal dichalcogenides and hence targeting massive and high-volume production for electronic device manufacturing.

  20. Ultra-Thin Coatings Beautify Art

    Science.gov (United States)

    2013-01-01

    The craftsmen in the Roman Empire who constructed the Lycurgus Cup 17 centuries ago probably didn't think their artifact would survive for nearly 2,000 years as a prized possession. And they certainly couldn't have known that the technology they used to make it would eventually become an important part of space exploration. Carved from one solid mass, the cup is one of the few complete glass objects from that period, and the only one made from dichroic glass. Meaning "two-colored" in Greek, dichroic glass was originally created by adding trace amounts of gold and silver to a large volume of glass melt. The resulting medium partially reflects the light passing through it, causing an observer to see different colors depending on the direction of the light source. The Lycurgus Cup, for example, is famous for appearing green in daylight and red when lit at night, symbolic of the ripening grapes used to fill it with wine. NASA revitalized the production of dichroic glass in the 1950s and 1960s as a means of protecting its astronauts. Ordinary clear substances cannot protect human vision from the harsh rays of unfiltered sunlight, and everything from the human body to spacecraft sensors and computers are at risk if left unprotected from the radiation that permeates space. The microscopic amounts of metal present in dichroic glass make it an effective barrier against such harmful radiation. While the ancient manufacturing technique called for adding metals to glass melt, NASA developed a process in which metals are vaporized by electron beams in a vacuum chamber and then applied directly to surfaces in an ultra-thin film. The vapor condenses in the form of crystal structures, and the process is repeated for up to several dozen coatings. The resulting material, still only about 30 millionths of an inch thick, is sufficient to reflect radiation even while the glass, or polycarbonate, as in the case of space suit helmets, remains transparent to the human eye.

  1. Nanowire decorated, ultra-thin, single crystalline silicon for photovoltaic devices.

    Science.gov (United States)

    Aurang, Pantea; Turan, Rasit; Unalan, Husnu Emrah

    2017-10-06

    Reducing silicon (Si) wafer thickness in the photovoltaic industry has always been demanded for lowering the overall cost. Further benefits such as short collection lengths and improved open circuit voltages can also be achieved by Si thickness reduction. However, the problem with thin films is poor light absorption. One way to decrease optical losses in photovoltaic devices is to minimize the front side reflection. This approach can be applied to front contacted ultra-thin crystalline Si solar cells to increase the light absorption. In this work, homojunction solar cells were fabricated using ultra-thin and flexible single crystal Si wafers. A metal assisted chemical etching method was used for the nanowire (NW) texturization of ultra-thin Si wafers to compensate weak light absorption. A relative improvement of 56% in the reflectivity was observed for ultra-thin Si wafers with the thickness of 20 ± 0.2 μm upon NW texturization. NW length and top contact optimization resulted in a relative enhancement of 23% ± 5% in photovoltaic conversion efficiency.

  2. Ultra-thin titanium nanolayers for plasmon-assisted enhancement of bioluminescence of chloroplast in biological light emitting devices

    Energy Technology Data Exchange (ETDEWEB)

    Hsun Su, Yen [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 70101, Taiwan (China); Hsu, Chia-Yun; Chang, Chung-Chien [Science and Technology of Accelerator Light Source, Hsinchu 300, Taiwan (China); Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 300, Taiwan (China); Tu, Sheng-Lung; Shen, Yun-Hwei [Department of Resource Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China)

    2013-08-05

    Ultra-thin titanium films were deposited via ultra-high vacuum ion beam sputter deposition. Since the asymmetric electric field of the metal foil plane matches the B-band absorption of chlorophyll a, the ultra-thin titanium nanolayers were able to generate surface plasmon resonance, thus enhancing the photoluminescence of chlorophyll a. Because the density of the states of plasmon resonance increases, the enhancement of photoluminescence also rises. Due to the biocompatibility and inexpensiveness of titanium, it can be utilized to enhance the bioluminescence of chloroplast in biological light emitting devices, bio-laser, and biophotonics.

  3. The properties of TiN ultra-thin films grown on SiO{sub 2} substrate by reactive high power impulse magnetron sputtering under various growth angles

    Energy Technology Data Exchange (ETDEWEB)

    Shayestehaminzadeh, S., E-mail: ses30@hi.is [Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik (Iceland); Tryggvason, T.K. [Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik (Iceland); Karlsson, L. [School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen (Germany); Olafsson, S. [Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik (Iceland); Gudmundsson, J.T. [Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik (Iceland); University of Michigan-Shanghai Jiao Tong University, University Joint Institute, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai 200240 (China)

    2013-12-02

    Thin TiN films were grown on SiO{sub 2} by reactive high power impulse magnetron sputtering (HiPIMS) and conventional dc magnetron sputtering (dcMS) while varying the angle between the target and the substrate surface from 0° (on-axis growth) to 90° (off-axis growth). Surface morphology and structural characterization were carried out using X-ray diffraction and reflection methods and the film properties were compared. The dcMS process shows higher growth rate than the HiPIMS process for on-axis grown films but the dcMS growth rate drops drastically for off-axis growth while the HiPIMS growth rate decreases slowly with increased angle between target and substrate for off-axis growth and becomes comparable to the dcMS growth rate. The dcMS grown films exhibit angle dependence in the density and surface roughness while the HiPIMS process creates denser and smoother films that are less angle dependent in all aspects. It was observed that the HiPIMS grown films remain poly-crystalline for all angles of rotation while the dcMS grown films are somewhat amorphous after 60°. The [111] and [200] grain sizes are comparable to the total film thickness in the HiPIMS grown films for all angles of rotation. In the case of dcMS, the [111], [200] and [220] grain sizes are roughly of the same size and much smaller than the total thickness for all growth angles except at 60° and higher. - Highlights: • TiN films were grown on SiO{sub 2} by HiPIMS and dcMS under various growth angles. • Influence of growth angle α = 0–90° on deposition rate and film quality was studied. • The HiPIMS process produces denser and smoother films for all growth angles. • At α = 0°, the growth rate of HiPIMS is 25% of dcMS while it is 50% at 90°. • The HiPIMS grown films remain poly-crystalline for all growth angles.

  4. Electroluminescence of organic light-emitting diodes with an ultra-thin layer of dopant

    Energy Technology Data Exchange (ETDEWEB)

    Li Weizhi [State Key Lab of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China); Yu Junsheng [State Key Lab of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China)], E-mail: jsyu@uestc.edu.cn; Wang, Tao [State Key Lab of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China); Jiang, Yadong [State Key Lab of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China)], E-mail: jiangyd@uestc.edu.cn; Wei, Bangxiong [State Key Lab of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China)

    2008-03-15

    Conventional fluorescent dyes, i.e., 4-(dicyanomethylene)-2-t-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB), 5,12-dihydro-5,12-dimethylquino [2,3-b]acridine-7,14-dione (DMQA) and 5,6,11,12-tetraphenylnaphthacene (Rubrene), were used to investigate the performance of organic light-emitting diodes (OLEDs) based on indium tin oxide (ITO)/N,N'-bis-(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (NPB)/tris-(8-hydroxyquinolate)-aluminum (Alq{sub 3})/MgAg. The dyes were either inserted into devices as an ultra-thin film at the NPB/Alq{sub 3} interface by sequential evaporation, or doped into the Alq{sub 3} emission layer by co-evaporation with the doping ratio about 2%. Electroluminescence (EL) spectra of devices indicated that concentration quenching effect (CQE) of the dye-dopant was slightly bigger in the former than in the latter, while the degrees of CQE for three dopants are in the order of DMQA > DCJTB > Rubrene suggested by the difference in EL spectra and performances of devices. In addition, EL process of device with an ultra-thin layer of dopant is dominated by direct carrier trapping (DCT) process due to almost no holes recombine with electrons in Alq{sub 3}-host layer.

  5. Ultra-Thin Optically Transparent Carbon Electrodes Produced from Layers of Adsorbed Proteins

    Science.gov (United States)

    Alharthi, Sarah A.; Benavidez, Tomas E.; Garcia, Carlos D.

    2013-01-01

    This work describes a simple, versatile, and inexpensive procedure to prepare optically transparent carbon electrodes, using proteins as precursors. Upon adsorption, the protein-coated substrates were pyrolyzed under reductive conditions (5% H2) to form ultra-thin, conductive electrodes. Because proteins spontaneously adsorb to interfaces forming uniform layers, the proposed method does not require a precise control of the preparation conditions, specialized instrumentation, or expensive precursors. The resulting electrodes were characterized by a combination of electrochemical, optical, and spectroscopic means. As a proof-of-concept, the optically-transparent electrodes were also used as substrate for the development of an electrochemical glucose biosensor. The proposed films represent a convenient alternative to more sophisticated, and less available, carbon-based nanomaterials. Furthermore, these films could be formed on a variety of substrates, without classical limitations of size or shape. PMID:23421732

  6. Highly reflective rear surface passivation design for ultra-thin Cu(In,Ga)Se{sub 2} solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Vermang, Bart, E-mail: Bart.Vermang@angstrom.uu.se [Ångström Solar Center, University of Uppsala, Uppsala 75121 (Sweden); ESAT-KU Leuven, University of Leuven, Leuven 3001 (Belgium); Wätjen, Jörn Timo; Fjällström, Viktor; Rostvall, Fredrik; Edoff, Marika [Ångström Solar Center, University of Uppsala, Uppsala 75121 (Sweden); Gunnarsson, Rickard; Pilch, Iris; Helmersson, Ulf [Plasma & Coatings Physics, University of Linköping, Linköping 58183 (Sweden); Kotipalli, Ratan; Henry, Frederic; Flandre, Denis [ICTEAM/IMNC, Université Catholique de Louvain, Louvain-la-Neuve 1348 (Belgium)

    2015-05-01

    Al{sub 2}O{sub 3} rear surface passivated ultra-thin Cu(In,Ga)Se{sub 2} (CIGS) solar cells with Mo nano-particles (NPs) as local rear contacts are developed to demonstrate their potential to improve optical confinement in ultra-thin CIGS solar cells. The CIGS absorber layer is 380 nm thick and the Mo NPs are deposited uniformly by an up-scalable technique and have typical diameters of 150 to 200 nm. The Al{sub 2}O{sub 3} layer passivates the CIGS rear surface between the Mo NPs, while the rear CIGS interface in contact with the Mo NP is passivated by [Ga]/([Ga] + [In]) (GGI) grading. It is shown that photon scattering due to the Mo NP contributes to an absolute increase in short circuit current density of 3.4 mA/cm{sup 2}; as compared to equivalent CIGS solar cells with a standard back contact. - Highlights: • Proof-of-principle ultra-thin CIGS solar cells have been fabricated. • The cells have Mo nano-particles (NPs) as local rear contacts. • An Al{sub 2}O{sub 3} film passivates the CIGS rear surface between these nano-particles. • [Ga]/([Ga] + [In]) grading is used to reduce Mo-NP/CIGS interface recombination.

  7. Performance regeneration of InGaZnO transistors with ultra-thin channels

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Binglei; Li, He; Zhang, Xijian, E-mail: zhangxijian@sdu.edu.cn, E-mail: songam@sdu.edu.cn; Luo, Yi; Wang, Qingpu [School of Physics, Shandong University, Jinan 250100 (China); Song, Aimin, E-mail: zhangxijian@sdu.edu.cn, E-mail: songam@sdu.edu.cn [School of Physics, Shandong University, Jinan 250100 (China); School of Electrical and Electronic Engineering, University of Manchester, Manchester M13 9PL (United Kingdom)

    2015-03-02

    Thin-film transistors (TFTs) based on ultra-thin amorphous indium gallium zinc oxide (a-IGZO) semiconductors down to 4 nm were studied motivated by the increasing cost of indium. At and below 5 nm, it was found that the field-effect mobility was severely degraded, the threshold voltage increased, and the output characteristics became abnormal showing no saturated current. By encapsulating a layer of polymethyl methacrylate on the IGZO TFTs, the performance of the 5-nm-thick device was effectively recovered. The devices also showed much higher on/off ratios, improved hysteresis, and normal output characteristic curves as compared with devices not encapsulated. The stability of the encapsulated devices was also studied over a four month period.

  8. Ultra-thin alumina and silicon nitride MEMS fabricated membranes for the electron multiplication

    Science.gov (United States)

    Prodanović, V.; Chan, H. W.; Graaf, H. V. D.; Sarro, P. M.

    2018-04-01

    In this paper we demonstrate the fabrication of large arrays of ultrathin freestanding membranes (tynodes) for application in a timed photon counter (TiPC), a novel photomultiplier for single electron detection. Low pressure chemical vapour deposited silicon nitride (Si x N y ) and atomic layer deposited alumina (Al2O3) with thicknesses down to only 5 nm are employed for the membrane fabrication. Detailed characterization of structural, mechanical and chemical properties of the utilized films is carried out for different process conditions and thicknesses. Furthermore, the performance of the tynodes is investigated in terms of secondary electron emission, a fundamental attribute that determines their applicability in TiPC. Studied features and presented fabrication methods may be of interest for other MEMS application of alumina and silicon nitride as well, in particular where strong ultra-thin membranes are required.

  9. Design of an ultra-thin dual band infrared system

    Science.gov (United States)

    Du, Ke; Cheng, Xuemin; Lv, Qichao; Hu, YiFei

    2014-11-01

    The ultra-thin imaging system using reflective multiple-fold structure has smaller volume and less weight while maintaining high resolution compared with conventional optical systems. The multi-folded approach can significantly extend focal distance within wide spectral range without incurring chromatic aberrations. In this paper, we present a dual infrared imaging system of four-folded reflection with two air-spaced concentric reflective surfaces. The dual brand IR system has 107mm effective focal length, 0.7NA, +/-4° FOV, and 50mm effective aperture with 80mm outer diameter into a 25mm total thickness, which spectral response is 3~12μm.

  10. Design of a CMOS readout circuit on ultra-thin flexible silicon chip for printed strain gauges

    Directory of Open Access Journals (Sweden)

    M. Elsobky

    2017-09-01

    Full Text Available Flexible electronics represents an emerging technology with features enabling several new applications such as wearable electronics and bendable displays. Precise and high-performance sensors readout chips are crucial for high quality flexible electronic products. In this work, the design of a CMOS readout circuit for an array of printed strain gauges is presented. The ultra-thin readout chip and the printed sensors are combined on a thin Benzocyclobutene/Polyimide (BCB/PI substrate to form a Hybrid System-in-Foil (HySiF, which is used as an electronic skin for robotic applications. Each strain gauge utilizes a Wheatstone bridge circuit, where four Aerosol Jet® printed meander-shaped resistors form a full-bridge topology. The readout chip amplifies the output voltage difference (about 5 mV full-scale swing of the strain gauge. One challenge during the sensor interface circuit design is to compensate for the relatively large dc offset (about 30 mV at 1 mA in the bridge output voltage so that the amplified signal span matches the input range of an analog-to-digital converter (ADC. The circuit design uses the 0. 5 µm mixed-signal GATEFORESTTM technology. In order to achieve the mechanical flexibility, the chip fabrication is based on either back thinned wafers or the ChipFilmTM technology, which enables the manufacturing of silicon chips with a thickness of about 20 µm. The implemented readout chip uses a supply of 5 V and includes a 5-bit digital-to-analog converter (DAC, a differential difference amplifier (DDA, and a 10-bit successive approximation register (SAR ADC. The circuit is simulated across process, supply and temperature corners and the simulation results indicate excellent performance in terms of circuit stability and linearity.

  11. Characterization of Ultra thin chromium layers deposited ou to SiO2 using the Le-PIXE and the RB S techniques

    International Nuclear Information System (INIS)

    Zahraman, K.; Nsouli, B.; Roumie, M.

    2007-01-01

    In this paper, we demonstrate the ability of the Le-PIXE (Low Energy PIXE) technique, using proton energies < 1 MeV, for the monitoring of the thickness and the thickness uniformity of ultra thin (0.5 nm < t < 20 nm) chromium layers deposited onto quartz substrates. Chromium is a good candidate for obtaining conductive ultra thin layers on insulator substrates such as quartz (SiO2). The resistivity of such layers is highly related to the quality of the deposited chromium film. In order to optimize the deposition process, there is a need for rapid and accurate monitoring of such films (film thickness, thickness uniformity over a big surface...). The acquisition time needed to obtain results with less than 3-4 % precision was 5 minutes for the thinnest layers. The validation for the use of the Le-PIXE technique was checked by means of conventional RB S technique.

  12. Sensitive thermal transitions of nanoscale polymer samples using the bimetallic effect: application to ultra-thin polythiophene.

    Science.gov (United States)

    Ahumada, O; Pérez-Madrigal, M M; Ramirez, J; Curcó, D; Esteves, C; Salvador-Matar, A; Luongo, G; Armelin, E; Puiggalí, J; Alemán, C

    2013-05-01

    A sensitive nanocalorimetric technology based on microcantilever sensors is presented. The technology, which combines very short response times with very small sample consumption, uses the bimetallic effect to detect thermal transitions. Specifically, abrupt variations in the Young's modulus and the thermal expansion coefficient produced by temperature changes have been employed to detect thermodynamic transitions. The technology has been used to determine the glass transition of poly(3-thiophene methyl acetate), a soluble semiconducting polymer with different nanotechnological applications. The glass transition temperature determined using microcantilevers coated with ultra-thin films of mass = 10(-13) g is 5.2 °C higher than that obtained using a conventional differential scanning calorimeter for bulk powder samples of mass = 5 × 10(-3) g. Atomistic molecular dynamics simulations on models that represent the bulk powder and the ultra-thin films have been carried out to provide understanding and rationalization of this feature. Simulations indicate that the film-air interface plays a crucial role in films with very small thickness, affecting both the organization of the molecular chains and the response of the molecules against the temperature.

  13. Ultra-thin infrared metamaterial detector for multicolor imaging applications.

    Science.gov (United States)

    Montoya, John A; Tian, Zhao-Bing; Krishna, Sanjay; Padilla, Willie J

    2017-09-18

    The next generation of infrared imaging systems requires control of fundamental electromagnetic processes - absorption, polarization, spectral bandwidth - at the pixel level to acquire desirable information about the environment with low system latency. Metamaterial absorbers have sparked interest in the infrared imaging community for their ability to enhance absorption of incoming radiation with color, polarization and/or phase information. However, most metamaterial-based sensors fail to focus incoming radiation into the active region of a ultra-thin detecting element, thus achieving poor detection metrics. Here our multifunctional metamaterial absorber is directly integrated with a novel mid-wave infrared (MWIR) and long-wave infrared (LWIR) detector with an ultra-thin (~λ/15) InAs/GaSb Type-II superlattice (T2SL) interband cascade detector. The deep sub-wavelength metamaterial detector architecture proposed and demonstrated here, thus significantly improves the detection quantum efficiency (QE) and absorption of incoming radiation in a regime typically dominated by Fabry-Perot etalons. Our work evinces the ability of multifunctional metamaterials to realize efficient wavelength selective detection across the infrared spectrum for enhanced multispectral infrared imaging applications.

  14. Ultra thin films for sensing and heating of microprobes

    NARCIS (Netherlands)

    Gaitas, A.

    2013-01-01

    This dissertation aims to advance the current state of cantilevers with integrated metal thermal and deflection sensing elements. Metallic sensing elements enable the use of alternative substrate materials (such as polymers), that tend to exhibit higher compliance properties and are more robust

  15. Ultra thin films of nanocrystalline Ge studied by AFM and ...

    Indian Academy of Sciences (India)

    Unknown

    peak position and an asymmetrical broadening on the lower frequency side when compared with the spectrum of the bulk Ge sample. The shift of the Raman .... resultant fit to Ic(ω) (1) (thin line) and a Lorentzian function (dotted line). Figure 6 shows Raman spectra of the samples B and C. A shoulder at 280 cm–1 can be.

  16. Mechanical and electrical properties of ultra-thin chips and flexible electronics assemblies during bending

    NARCIS (Netherlands)

    Van Den Ende, D.A.; Van De Wiel, H.J.; Kusters, R.H.L.; Sridhar, A.; Schram, J.F.M.; Cauwe, M.; Van Den Brand, J.

    2014-01-01

    Ultra-thin chips of less than 20 μm become flexible, allowing integration of silicon IC technology with highly flexible electronics such as food packaging sensor systems or healthcare and sport monitoring tags as wearable patches or even directly in clothing textile. The ultra-thin chips in these

  17. A novel high performance, ultra thin heat sink for electronics

    International Nuclear Information System (INIS)

    Escher, W.; Michel, B.; Poulikakos, D.

    2010-01-01

    We present an ultra thin heat sink for electronics, combining optimized impinging slot-jets, micro-channels and manifolds for efficient cooling. We first introduce a three-dimensional numerical model of the heat transfer structure, to investigate its hydrodynamic and thermal performance and its sensitivity to geometric parameters. In a second step we propose a three-dimensional hydrodynamic numerical model representing the complete system. Based on this model we design a novel manifold providing uniform fluid distribution. In order to save computational time a simpler semi-empirical model is proposed and validated. The semi-empirical model allows a robust optimization of the heat sink geometric parameters. The design is optimized for a 2 x 2 cm 2 chip and provides a total thermal resistance of 0.087 cm 2 K/W for flow rates 2 for a temperature difference between fluid inlet and chip of 65 K.

  18. Transport properties of ultra-thin granular YBa2Cu3O7−δ nanobridges

    International Nuclear Information System (INIS)

    Bar, E.; Levi, D.; Koren, G.; Shaulov, A.; Yeshurun, Y.

    2014-01-01

    Highlights: • Nano bridges were patterned on laser ablated ultra-thin YBa 2 Cu 3 O 7 films. • Magneto-transport measurements reveal phenomena that are usually absent in the bulk. • Magnetoresistance (MR) oscillation point to effect of granularity. • Negative MR at low fields and negative MR slope at high fields were observed. • V-I curves exhibit voltage jumps at temperatures well below T c . - Abstract: Magneto-transport measurements in YBa 2 Cu 3 O 7 nanobridges, patterned on laser ablated ultra-thin films, reveal phenomena that are usually absent in the bulk of the material. These include broadening of the resistive transition, magnetoresistance oscillation, negative magnetoresistance at low fields, negative magnetoresistance slope at high fields, and V–I curves that exhibit voltage jumps at temperatures well below T c . These phenomena, attributed to the granular nature of the bridges, should be taken into account in any future attempts to utilize such bridges in technological applications

  19. Integration of plasmonic Ag nanoparticles as a back reflector in ultra-thin Cu(In,Ga)Se_2 solar cells

    International Nuclear Information System (INIS)

    Yin, Guanchao; Steigert, Alexander; Andrae, Patrick; Goebelt, Manuela; Latzel, Michael; Manley, Phillip; Lauermann, Iver; Christiansen, Silke; Schmid, Martina

    2015-01-01

    Graphical abstract: Plasmonic Ag nanoparticles as a back reflector in ultra-thin Cu(In,Ga)Se_2 (CIGSe) solar cells are investigated. Ag diffusion is successfully passivated by reducing the substrate temperature and introducing a 50 nm atomic layer deposition (ALD) prepared Al_2O_3 film. This clears the thermal obstacle in incorporating Ag nanoparticles in CIGSe solar cells. Simulations show that Ag nanoparticles have the potential to greatly enhance the light absorption in ultra-thin CIGSe solar cells. - Highlights: • Ag nanoparticles are able to diffuse through ITO substrate into CIGSe absorber even at a low substrate temperature of 440 °C. • The direction (inserting a dielectric passivation layer) to thermally block the Ag diffusion and the requirements for the passivation layer are indicated and generalized. • An atomic layer deposited Al_2O_3 layer is experimentally proved to be able to thermally passivate the Ag nanoparticles, which clears the thermal obstacle in using Ag nanoparticles as a back reflector in ultra-thin CIGSe solar cells. • It is theoretically proved that the Ag nanoparticles as a back reflector have the potential to effectively enhance the absorption in ultra-thin CIGSe solar cells. - Abstract: Integration of plasmonic Ag nanoparticles as a back reflector in ultra-thin Cu(In,Ga)Se_2 (CIGSe) solar cells is investigated. X-ray photoelectron spectroscopy results show that Ag nanoparticles underneath a Sn:In_2O_3 back contact could not be thermally passivated even at a low substrate temperature of 440 °C during CIGSe deposition. It is shown that a 50 nm thick Al_2O_3 film prepared by atomic layer deposition is able to block the diffusion of Ag, clearing the thermal obstacle in utilizing Ag nanoparticles as a back reflector in ultra-thin CIGSe solar cells. Via 3-D finite element optical simulation, it is proved that the Ag nanoparticles show the potential to contribute the effective absorption in CIGSe solar cells.

  20. Fatigue-resistant epitaxial Pb(Zr,Ti)O3 capacitors on Pt electrode with ultra-thin SrTiO3 template layers

    International Nuclear Information System (INIS)

    Takahara, Seiichi; Morimoto, Akiharu; Kawae, Takeshi; Kumeda, Minoru; Yamada, Satoru; Ohtsubo, Shigeru; Yonezawa, Yasuto

    2008-01-01

    Lead zirconate-titanate Pb(Zr,Ti)O 3 (PZT) capacitors with Pt bottom electrodes were prepared on MgO substrates by pulsed laser deposition (PLD) technique employing SrTiO 3 (STO) template layer. Perovskite PZT thin films are prepared via stoichiometric target using the ultra-thin STO template layers while it is quite difficult to obtain the perovskite PZT on Pt electrode via stoichiometric target in PLD process. The PZT capacitor prepared with the STO template layer showed good hysteresis and leakage current characteristics, and it showed an excellent fatigue resistance. The ultra-thin STO template layers were characterized by angle-resolved X-ray photoelectron spectroscopy measurement. The effect of the STO template layer is discussed based on the viewpoint of the perovskite nucleation and diffusion of Pb and O atoms

  1. Ultrasonic force microscopy: detection and imaging of ultra-thin molecular domains.

    Science.gov (United States)

    Dinelli, Franco; Albonetti, Cristiano; Kolosov, Oleg V

    2011-03-01

    The analysis of the formation of ultra-thin organic films is a very important issue. In fact, it is known that the properties of organic light emitting diodes and field effect transistors are strongly affected by the early growth stages. For instance, in the case of sexithiophene, the presence of domains made of molecules with the backbone parallel to the substrate surface has been indirectly evidenced by photoluminescence spectroscopy and confocal microscopy. On the contrary, conventional scanning force microscopy both in contact and intermittent contact modes have failed to detect such domains. In this paper, we show that Ultrasonic Force Microscopy (UFM), sensitive to nanomechanical properties, allows one to directly identify the structure of sub-monolayer thick films. Sexithiophene flat domains have been imaged for the first time with nanometer scale spatial resolution. A comparison with lateral force and intermittent contact modes has been carried out in order to explain the origins of the UFM contrast and its advantages. In particular, it indicates that UFM is highly suitable for investigations where high sensitivity to material properties, low specimen damage and high spatial resolution are required. Copyright © 2010 Elsevier B.V. All rights reserved.

  2. Ultra-Thin Solid-State Nanopores: Fabrication and Applications

    Science.gov (United States)

    Kuan, Aaron Tzeyang

    Solid-state nanopores are a nanofluidic platform with unique advantages for single-molecule analysis and filtration applications. However, significant improvements in device performance and scalable fabrication methods are needed to make nanopore devices competitive with existing technologies. This dissertation investigates the potential advantages of ultra-thin nanopores in which the thickness of the membrane is significantly smaller than the nanopore diameter. Novel, scalable fabrication methods were first developed and then utilized to examine device performance for water filtration and single molecule sensing applications. Fabrication of nanometer-thin pores in silicon nitride membranes was achieved using a feedback-controlled ion beam method in which ion sputtering is arrested upon detection of the first few ions that drill through the membrane. Performing fabrication at liquid nitrogen temperatures prevents surface atom rearrangements that have previously complicated similar processes. A novel cross-sectional imaging method was also developed to allow careful examination of the full nanopore geometry. Atomically-thin graphene nanopores were fabricated via an electrical pulse method in which sub-microsecond electrical pulses applied across a graphene membrane in electrolyte solution are used to create a defect in the membrane and controllably enlarge it into a nanopore. This method dramatically increases the accuracy and reliability of graphene nanopore production, allowing consistent production of single nanopores down to subnanometer sizes. In filtration applications in which nanopores are used to selectively restrict the passage of dissolved contaminants, ultra-thin nanopores minimize the flow resistance, increasing throughput and energy-efficiency. The ability of graphene nanopores to separate different ions was characterized via ionic conductance and reversal potential measurements. Graphene nanopores were observed to conduct cations preferentially over

  3. Electronic structures of ultra-thin silicon carbides deposited on graphite

    International Nuclear Information System (INIS)

    Baba, Y.; Sekiguchi, T.; Shimoyama, I.; Nath, Krishna G.

    2004-01-01

    Electronic structures of ultra-thin silicon carbide films have been investigated by X-ray photoelectron spectroscopy (XPS) and Si K-edge X-ray absorption near edge structure (XANES) using linearly polarized synchrotron soft X-rays. Silicon carbide films were deposited on the surface of highly oriented pyrolytic graphite (HOPG) by ion beam deposition method. Tetramethylsilane (Si(CH 3 ) 4 ) was used as a discharge gas. The XPS and XANES features for the thick layers were similar to those for the bulk SiC. For sub-monolayered films, the Si 1s binding energy in XPS was higher by 2.5 eV than that for bulk SiC. This suggests the existence of low-dimensional SiC x where the silicon atoms are more positively charged than those in bulk SiC. After annealing the sub-monolayered film at 850 deg. C, a new peak appeared around 1840 eV in the XANES spectrum. The energy of this new peak was lower than those for any other silicon compounds. The low-energy feature of the XANES peak suggests the existence of π*-like orbitals around the silicon atom. On the basis of the polarization dependencies of the XANES spectra, it was revealed that the direction of the π*-like orbitals are nearly perpendicular to the surface. We conclude that sub-monolayered SiC x film exhibits flat-lying structure of which configuration is similar to a single sheet of graphite

  4. Role of interlayer coupling in ultra thin MoS2

    KAUST Repository

    Cheng, Yingchun; Zhu, Zhiyong; Schwingenschlö gl, Udo

    2012-01-01

    The effects of interlayer coupling on the vibrational and electronic properties of ultra thin MoS 2 were studied by ab initio calculations. For smaller slab thickness, the interlayer distance is significantly elongated because of reduced interlayer

  5. Ultra thin layer activation by recoil implantation of radioactive heavy ions. Applicability in wear and corrosion studies

    International Nuclear Information System (INIS)

    Lacroix, O.; Sauvage, T.; Blondiaux, G.; Guinard, L.

    1997-07-01

    A new calibration procedure is proposed for the application of recoil implantation of radioactive heavy ions (energies between a few hundred keV and a few MeV) into the near surface of materials as part of a research programme on sub-micrometric wear or corrosion phenomena. The depth profile of implanted radioelements is performed by using ultra thin deposited films obtained by cathode sputtering under argon plasma. Two curves for 56 Co ion in nickel have been determined for implantation depths of 110 and 200 nm, respectively, and stress the feasibility and reproducibility of this method for such activated depths. The achieved surface loss detection sensitivities are about 1 and 2 nm respectively. The on line detection mode is performed directly on the sample of interest. A general description of the method is presented. A study of the reaction kinematics followed by a general treatment on the irradiation parameters to be adopted are also developed with the intention of using the ultra thin layer activation method (UTLA) to further applications in research and industry. (author)

  6. Axial ion channeling patterns from ultra-thin silicon membranes

    International Nuclear Information System (INIS)

    Motapothula, M.; Dang, Z.Y.; Venkatesan, T.; Breese, M.B.H.; Rana, M.A.; Osman, A.

    2012-01-01

    We present channeling patterns produced by MeV protons transmitted through 55 nm thick [0 0 1] silicon membranes showing the early evolution of the axially channeled beam angular distribution for small tilts away from the [0 0 1], [0 1 1] and [1 1 1] axes. Instead of a ring-like “doughnut” distribution previously observed at small tilts to major axes in thicker membranes, geometric shapes such as squares and hexagons are observed along different axes in ultra-thin membranes. The different shapes arise because of the highly non-equilibrium transverse momentum distribution of the channeled beam during its initial propagation in the crystal and the reduced multiple scattering which allows the fine angular structure to be resolved. We describe a simple geometric construction of the intersecting planar channels at an axis to gain insight into the origin of the geometric shapes observed in such patterns and how they evolve into the ‘doughnut’ distributions in thicker crystals.

  7. Oxygen Sensing by the Hybrid Langmuir-Blodgett Films of Iridium(III Complexes and Synthetic Saponite on the Basis of Energy Transfer

    Directory of Open Access Journals (Sweden)

    Hisako Sato

    2017-09-01

    Full Text Available An ultra-thin hybrid film of amphiphilic iridium(III complexes and synthetic saponite was manipulated by means of the modified Langmuir-Blodgett method. In the film deposited onto a quartz substrate, the external mixed molecular layer of amphiphilic iridium(III complexes was reinforced by the inner layer of exfoliated synthetic saponite. As components of the molecular layer, two iridium(III complexes were used: [Ir(dfppy2(dc9bpy]+ (dfppyH = 2-(4′,6′-difluorophenyl pyridine; dc9bpy = 4,4′-dinonyl-2,2′-bipyridine (denoted as DFPPY and [Ir(piq2(dc9bpy]+ (piqH = 1-phenyisoquinoline denoted as PIQ. The emission spectra from the films changed from blue to red maxima with the decrease of a ratio of DFPPY/PIQ due to the energy transfer from excited DFPPY to PIQ. The intensity of red decreased with the increase of oxygen pressure through the quenching of excited iridium(III complexes, promising a possibility as an oxygen-sensing film.

  8. Prediction of transmittance spectra for transparent composite electrodes with ultra-thin metal layers

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Zhao; Alford, T. L., E-mail: TA@asu.edu [School for Engineering of Matter, Transport, and Energy, Arizona State University, Tempe, Arizona 85287 (United States); Khorasani, Arash Elhami [ON Semiconductor Corp., Phoenix, Arizona 85005 (United States); Theodore, N. D. [CHD-Fab, Freescale Semiconductor Inc., Tempe, Arizona 85224 (United States); Dhar, A. [Intel Corp., 2501 NW 229th Ave, Hillsboro, Oregon 97124 (United States)

    2015-11-28

    Recent interest in indium-free transparent composite-electrodes (TCEs) has motivated theoretical and experimental efforts to better understand and enhance their electrical and optical properties. Various tools have been developed to calculate the optical transmittance of multilayer thin-film structures based on the transfer-matrix method. However, the factors that affect the accuracy of these calculations have not been investigated very much. In this study, two sets of TCEs, TiO{sub 2}/Au/TiO{sub 2} and TiO{sub 2}/Ag/TiO{sub 2}, were fabricated to study the factors that affect the accuracy of transmittance predictions. We found that the predicted transmittance can deviate significantly from measured transmittance for TCEs that have ultra-thin plasmonic metal layers. The ultrathin metal layer in the TCE is typically discontinuous. When light interacts with the metallic islands in this discontinuous layer, localized surface plasmons are generated. This causes extra light absorption, which then leads to the actual transmittance being lower than the predicted transmittance.

  9. Laser Radiation Pressure Acceleration of Monoenergetic Protons in an Ultra-Thin Foil

    Science.gov (United States)

    Eliasson, Bengt; Liu, Chuan S.; Shao, Xi; Sagdeev, Roald Z.; Shukla, Padma K.

    2009-11-01

    We present theoretical and numerical studies of the acceleration of monoenergetic protons in a double layer formed by the laser irradiation of an ultra-thin film. The stability of the foil is investigated by direct Vlasov-Maxwell simulations for different sets of laser-plasma parameters. It is found that the foil is stable, due to the trapping of both electrons and ions in the thin laser-plasma interaction region, where the electrons are trapped in a potential well composed of the ponderomo-tive potential of the laser light and the electrostatic potential due to the ions, and the ions are trapped in a potential well composed of the inertial potential in an accelerated frame and the electrostatic potential due to the electrons. The result is a stable double layer, where the trapped ions are accelerated to monoenergetic energies up to 100 MeV and beyond, which makes them suitable for medical applications cancer treatment. The underlying physics of trapped and untapped ions in a double layer is also investigated theoretically and numerically.

  10. Dual-side and three-dimensional microelectrode arrays fabricated from ultra-thin silicon substrates

    International Nuclear Information System (INIS)

    Du, Jiangang; Masmanidis, Sotiris C; Roukes, Michael L

    2009-01-01

    A method for fabricating planar implantable microelectrode arrays was demonstrated using a process that relied on ultra-thin silicon substrates, which ranged in thickness from 25 to 50 µm. The challenge of handling these fragile materials was met via a temporary substrate support mechanism. In order to compensate for putative electrical shielding of extracellular neuronal fields, separately addressable electrode arrays were defined on each side of the silicon device. Deep reactive ion etching was employed to create sharp implantable shafts with lengths of up to 5 mm. The devices were flip-chip bonded onto printed circuit boards (PCBs) by means of an anisotropic conductive adhesive film. This scalable assembly technique enabled three-dimensional (3D) integration through formation of stacks of multiple silicon and PCB layers. Simulations and measurements of microelectrode noise appear to suggest that low impedance surfaces, which could be formed by electrodeposition of gold or other materials, are required to ensure an optimal signal-to-noise ratio as well a low level of interchannel crosstalk

  11. Interface analysis of Ge ultra thin layers intercalated between GaAs substrates and oxide stacks

    Energy Technology Data Exchange (ETDEWEB)

    Molle, Alessandro, E-mail: alessandro.molle@mdm.infm.i [Laboratorio Nazionale MDM, CNR-INFM, Via C. Olivetti 2, 20041 Agrate Brianza (Italy); Lamagna, Luca; Spiga, Sabina [Laboratorio Nazionale MDM, CNR-INFM, Via C. Olivetti 2, 20041 Agrate Brianza (Italy); Fanciulli, Marco [Laboratorio Nazionale MDM, CNR-INFM, Via C. Olivetti 2, 20041 Agrate Brianza (MI) (Italy); Dipartimento di Scienza dei Materiali, Universita di Milano Bicocca, Milano (Italy); Brammertz, Guy; Meuris, Marc [IMEC, 75 Kapeldreef, B-3001 Leuven (Belgium)

    2010-01-01

    Capping III-V compound surfaces with Ge ultra-thin layer might be a viable pathway to passivate the electrically active interface traps which usually jeopardize the integration of III-V materials in metal-oxide-semiconductor devices. As the physical nature of such traps is intrinsically related to the chemical details of the interface composition, the structural and compositional features of the Ge/GaAs interface were thoroughly investigated in two different configurations, the atomic layer deposition of La-doped ZrO{sub 2} films on Ge-capped GaAs and the ultra-high vacuum based molecular beam deposition of GeO{sub 2}/Ge double stack on in situ prepared GaAs. In the former case, the intercalation of a Ge interface layer is shown to suppress the concentration of interface Ga-O, As-O and elemental As bonding which were significantly detected in case of the direct oxide deposition on GaAs. In the latter case, the incidence of two different in situ surface preparations, the Ar sputtering and the atomic H cleaning, on the interface composition is elucidated and the beneficial role played by the atomic H exposure in reducing the semiconductor-oxygen bonds at the interface level is demonstrated.

  12. Electrodeposition of hybrid ZnO/organic dye films

    Energy Technology Data Exchange (ETDEWEB)

    Moya, Monica; Mari, Bernabe; Mollar, Miquel [Department de Fisica Aplicada-IDF, Universitat Politecnica de Valencia, Cami de Vera s/n, 46022 Valencia (Spain)

    2011-06-15

    The viability of the electrodeposition as a suitable technique for preparing new porous hybrid materials has been tested in this paper. Hybrid ZnO films with two different organic dyes: Eosin-Y and Tetrasulphonated-Cu-phtalocyanine were prepared. Their physical and chemical properties as well as their dependence on the growth conditions were investigated. It is found that the type of dye has a big influence on the morphology and porosity of hybrid films. Open and connected pores are created in hybrid ZnO/Eosin-Y films while both open and closed pores coexist in hybrid ZnO/Tetrasulfonated-Cu-phthalocyanine. As one of the promising applications of hybrid materials is photovoltaic conversion of sunlight, photoelectrochemical characterization of hybrid films is also reported. Photocurrent generation owing to both contributions ZnO and Eosin-Y is observed in ZnO/Eosin-Y films but no photocurrent has been observed in ZnO/Tetrasulfonated-Cu-phthalocyanine films. SEM micrographs of hybrid ZnO films grown in aqueous bath; (Left) ZnO/Eosin-Y films grown at 70 C, -0.9 V (Right) ZnO/Ts-CuPc films grown at 70 C, -0.9 V. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Ultra-thin Polyethylene glycol Coatings for Stem Cell Culture

    Science.gov (United States)

    Schmitt, Samantha K.

    Human mesenchymal stem cells (hMSCs) are a widely accessible and a clinically relevant cell type that are having a transformative impact on regenerative medicine. However, current clinical expansion methods can lead to selective changes in hMSC phenotype resulting from relatively undefined cell culture surfaces. Chemically defined synthetic surfaces can aid in understanding stem cell behavior. In particular we have developed chemically defined ultra-thin coatings that are stable over timeframes relevant to differentiation of hMSCs (several weeks). The approach employs synthesis of a copolymer with distinct chemistry in solution before application to a substrate. This provides wide compositional flexibility and allows for characterization of the orthogonal crosslinking and peptide binding groups. Characterization is done in solution by proton NMR and after crosslinking by X-ray photoelectron spectroscopy (XPS). The solubility of the copolymer in ethanol and low temperature crosslinking, expands its applicability to plastic substrates, in addition to silicon, glass, and gold. Cell adhesive peptides, namely Arg-Gly-Asp (RGD) fragments, are coupled to coating via different chemistries resulting in the urethane, amide or the thioester polymer-peptide bonds. Development of azlactone-based chemistry allowed for coupling in water at low peptide concentrations and resulted in either an amide or thioester bonds, depending on reactants. Characterization of the peptide functionalized coating by XPS, infrared spectroscopy and cell culture assays, showed that the amide linkages can present peptides for multiple weeks, while shorter-term presentation of a few days is possible using the more labile thioester bond. Regardless, coatings promoted initial adhesion and spreading of hMSCs in a peptide density dependent manner. These coatings address the following challenges in chemically defined cell culture simultaneously: (i) substrate adaptability, (ii) scalability over large areas

  14. Dielectric properties of PMMA-SiO2 hybrid films

    KAUST Repository

    Morales-Acosta, M. D.; Quevedo-Ló pez, Manuel Angel Quevedo; Alshareef, Husam N.; Gnade, Bruce E.; Ramí rez-Bon, Rafael

    2010-01-01

    Organic-inorganic hybrid films were synthesized by a modified sol-gel process. PMMASiO2 films were prepared using methylmethacrylate (MMA), tetraethil-orthosilicate (TEOS) as silicon dioxide source, and 3-trimetoxi-silil-propil-methacrylate (TMSPM) as coupling agent. FTIR measurements were performed on the hybrid films to confirm the presence of PMMA-SiO2 bonding. In addition, metal-insulator-metal (MIM) devices were fabricated to study the dielectric constant of the films as function of frequency (1 KHz to 1 MHz). Electrical results show a weak trend of the dielectric constant of the hybrid films with MMA molar ratio. More importantly, the PMMA-SiO2 hybrid films showed a higher dielectric constant than SiO2 and PMMA layers, which is likely due to the presence of additional C-O-C bond. © (2010) Trans Tech Publications.

  15. Dielectric properties of PMMA-SiO2 hybrid films

    KAUST Repository

    Morales-Acosta, M. D.

    2010-03-01

    Organic-inorganic hybrid films were synthesized by a modified sol-gel process. PMMASiO2 films were prepared using methylmethacrylate (MMA), tetraethil-orthosilicate (TEOS) as silicon dioxide source, and 3-trimetoxi-silil-propil-methacrylate (TMSPM) as coupling agent. FTIR measurements were performed on the hybrid films to confirm the presence of PMMA-SiO2 bonding. In addition, metal-insulator-metal (MIM) devices were fabricated to study the dielectric constant of the films as function of frequency (1 KHz to 1 MHz). Electrical results show a weak trend of the dielectric constant of the hybrid films with MMA molar ratio. More importantly, the PMMA-SiO2 hybrid films showed a higher dielectric constant than SiO2 and PMMA layers, which is likely due to the presence of additional C-O-C bond. © (2010) Trans Tech Publications.

  16. Analyzing nitrogen concentration using carrier illumination (CI) technology for DPN ultra-thin gate oxide

    International Nuclear Information System (INIS)

    Li, W.S.; Wu, Bill; Fan, Aki; Kuo, C.W.; Segovia, M.; Kek, H.A.

    2005-01-01

    Nitrogen concentration in the gate oxide plays a key role for 90 nm and below ULSI technology. Techniques like secondary ionization mass spectroscopy (SIMS) and X-ray photoelectron spectroscopy (XPS) are commonly used for understanding N concentration. This paper describes the application of the carrier illuminationTM (CI) technique to measure the nitrogen concentration in ultra-thin gate oxides. A set of ultra-thin gate oxide wafers with different DPN (decoupled plasma nitridation) treatment conditions were measured using the CI technique. The CI signal has excellent correlation with the N concentration as measured by XPS

  17. Ultra-thin Cu2ZnSnS4 solar cell by pulsed laser deposition

    DEFF Research Database (Denmark)

    Cazzaniga, Andrea Carlo; Crovetto, Andrea; Yan, Chang

    2017-01-01

    We report on the fabrication of a 5.2% efficiency Cu2ZnSnS4 (CZTS) solar cell made by pulsed laser deposition (PLD) featuring an ultra-thin absorber layer (less than 450 nm). Solutions to the issues of reproducibility and micro-particulate ejection often encountered with PLD are proposed. At the ......We report on the fabrication of a 5.2% efficiency Cu2ZnSnS4 (CZTS) solar cell made by pulsed laser deposition (PLD) featuring an ultra-thin absorber layer (less than 450 nm). Solutions to the issues of reproducibility and micro-particulate ejection often encountered with PLD are proposed...

  18. The kinetics of dewetting ultra-thin Si layers from silicon dioxide

    International Nuclear Information System (INIS)

    Aouassa, M; Favre, L; Ronda, A; Berbezier, I; Maaref, H

    2012-01-01

    In this study, we investigate the kinetically driven dewetting of ultra-thin silicon films on silicon oxide substrate under ultra-high vacuum, at temperatures where oxide desorption and silicon lost could be ruled out. We show that in ultra-clean experimental conditions, the three different regimes of dewetting, namely (i) nucleation of holes, (ii) film retraction and (iii) coalescence of holes, can be quantitatively measured as a function of temperature, time and thickness. For a nominal flat clean sample these three regimes co-exist during the film retraction until complete dewetting. To discriminate their roles in the kinetics of dewetting, we have compared the dewetting evolution of flat unpatterned crystalline silicon layers (homogeneous dewetting), patterned crystalline silicon layers (heterogeneous dewetting) and amorphous silicon layers (crystallization-induced dewetting). The first regime (nucleation) is described by a breaking time which follows an exponential evolution with temperature with an activation energy E H ∼ 3.2 eV. The second regime (retraction) is controlled by surface diffusion of matter from the edges of the holes. It involves a very fast redistribution of matter onto the flat Si layer, which prevents the formation of a rim on the edges of the holes during both heterogeneous and homogeneous dewetting. The time evolution of the linear dewetting front measured during heterogeneous dewetting follows a characteristic power law x ∼ t 0.45 consistent with a surface diffusion-limited mechanism. It also evolves as x ∼ h -1 as expected from mass conservation in the absence of thickened rim. When the surface energy is isotropic (during dewetting of amorphous Si) the dynamics of dewetting is considerably modified: firstly, there is no measurable breaking time; secondly, the speed of dewetting is two orders of magnitude larger than for crystalline Si; and thirdly, the activation energy of dewetting is much smaller due to the different driving

  19. Finite Element Modelling of Bends and Creases during Folding Ultra Thin Stainless Steel Foils

    NARCIS (Netherlands)

    Datta, K.; Akagi, H.; Geijselaers, Hubertus J.M.; Huetink, Han

    2003-01-01

    Finite Element Modelling of an ultra thin foil of SUS 304 stainless steel is carried out. These foils are 20 mm and below in thickness. The development of stresses and strains during folding of these foils is studied. The objective of this study is to induce qualities of paper in the foils of

  20. Development and implementation of ultra-thin concrete road technology for suburban streets in South Africa

    CSIR Research Space (South Africa)

    Louw, MR

    2011-01-01

    Full Text Available Louw, FC Rust, AO Bergh and AH McKay DEVELOPMENT AND IMPLEMENTATIONN OF ULTRA- THIN CONCRETE ROAD TECHNOLOGY FOR SUBURBAN STREETS IN SOUTH AFRICA MR Louw, FC Rust, AO Bergh and AH McKay CSIR, Republic of South Africa rlouw...

  1. Ultra-thin ZnSe: Anisotropic and flexible crystal structure

    Energy Technology Data Exchange (ETDEWEB)

    Bacaksiz, C., E-mail: cihanbacaksiz@iyte.edu.tr [Department of Physics, Izmir Institute of Technology, 35430 Izmir (Turkey); Senger, R.T. [Department of Physics, Izmir Institute of Technology, 35430 Izmir (Turkey); Sahin, H. [Department of Photonics, Izmir Institute of Technology, 35430 Izmir (Turkey)

    2017-07-01

    Highlights: • Ultra-thin ZnSe is dynamically stable. • Ultra-thin ZnSe is electronically direct-gap semiconductor. • Ultra-thin ZnSe is ultra-flexible. • Ultra-thin ZnSe is mechanically in-plane anisotropic. - Abstract: By performing density functional theory-based calculations, we investigate the structural, electronic, and mechanical properties of the thinnest ever ZnSe crystal . The vibrational spectrum analysis reveals that the monolayer ZnSe is dynamically stable and has flexible nature with its soft phonon modes. In addition, a direct electronic band gap is found at the gamma point for the monolayer structure of ZnSe. We also elucidate that the monolayer ZnSe has angle dependent in-plane elastic parameters. In particular, the in-plane stiffness values are found to be 2.07 and 6.89 N/m for the arm-chair and zig-zag directions, respectively. The angle dependency is also valid for the Poisson ratio of the monolayer ZnSe. More significantly, the in-plane stiffness of the monolayer ZnSe is the one-tenth of Young modulus of bulk zb-ZnSe which indicates that the monolayer ZnSe is a quite flexible single layer crystal. With its flexible nature and in-plane anisotropic mechanical properties, the monolayer ZnSe is a good candidate for nanoscale mechanical applications.

  2. Ultra-thin ZnSe: Anisotropic and flexible crystal structure

    International Nuclear Information System (INIS)

    Bacaksiz, C.; Senger, R.T.; Sahin, H.

    2017-01-01

    Highlights: • Ultra-thin ZnSe is dynamically stable. • Ultra-thin ZnSe is electronically direct-gap semiconductor. • Ultra-thin ZnSe is ultra-flexible. • Ultra-thin ZnSe is mechanically in-plane anisotropic. - Abstract: By performing density functional theory-based calculations, we investigate the structural, electronic, and mechanical properties of the thinnest ever ZnSe crystal . The vibrational spectrum analysis reveals that the monolayer ZnSe is dynamically stable and has flexible nature with its soft phonon modes. In addition, a direct electronic band gap is found at the gamma point for the monolayer structure of ZnSe. We also elucidate that the monolayer ZnSe has angle dependent in-plane elastic parameters. In particular, the in-plane stiffness values are found to be 2.07 and 6.89 N/m for the arm-chair and zig-zag directions, respectively. The angle dependency is also valid for the Poisson ratio of the monolayer ZnSe. More significantly, the in-plane stiffness of the monolayer ZnSe is the one-tenth of Young modulus of bulk zb-ZnSe which indicates that the monolayer ZnSe is a quite flexible single layer crystal. With its flexible nature and in-plane anisotropic mechanical properties, the monolayer ZnSe is a good candidate for nanoscale mechanical applications.

  3. Opto-electrical approaches for high efficiency and ultra-thin c-Si solar cells

    NARCIS (Netherlands)

    Ingenito, A.; Isabella, O.; Zeman, M.

    2014-01-01

    The need for cost reduction requires using less raw material and cost-effective processes without sacrificing the conversion efficiency. For keeping high the generated photo-current, an advanced light trapping scheme for ultra-thin silicon wafers is here proposed, exhibiting absorptances up to 99%

  4. Estimating the thickness of ultra thin sections for electron microscopy by image statistics

    DEFF Research Database (Denmark)

    Sporring, Jon; Khanmohammadi, Mahdieh; Darkner, Sune

    2014-01-01

    We propose a method for estimating the thickness of ultra thin histological sections by image statistics alone. Our method works for images, that are the realisations of a stationary and isotropic stochastic process, and it relies on the existence of statistical image-measures that are strictly m...

  5. Nano-Photonic Structures for Light Trapping in Ultra-Thin Crystalline Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    Prathap Pathi

    2017-01-01

    Full Text Available Thick wafer-silicon is the dominant solar cell technology. It is of great interest to develop ultra-thin solar cells that can reduce materials usage, but still achieve acceptable performance and high solar absorption. Accordingly, we developed a highly absorbing ultra-thin crystalline Si based solar cell architecture using periodically patterned front and rear dielectric nanocone arrays which provide enhanced light trapping. The rear nanocones are embedded in a silver back reflector. In contrast to previous approaches, we utilize dielectric photonic crystals with a completely flat silicon absorber layer, providing expected high electronic quality and low carrier recombination. This architecture creates a dense mesh of wave-guided modes at near-infrared wavelengths in the absorber layer, generating enhanced absorption. For thin silicon (<2 μm and 750 nm pitch arrays, scattering matrix simulations predict enhancements exceeding 90%. Absorption approaches the Lambertian limit at small thicknesses (<10 μm and is slightly lower (by ~5% at wafer-scale thicknesses. Parasitic losses are ~25% for ultra-thin (2 μm silicon and just 1%–2% for thicker (>100 μm cells. There is potential for 20 μm thick cells to provide 30 mA/cm2 photo-current and >20% efficiency. This architecture has great promise for ultra-thin silicon solar panels with reduced material utilization and enhanced light-trapping.

  6. Nanostructured hybrid ZnO thin films for energy conversion

    Directory of Open Access Journals (Sweden)

    Samantilleke Anura

    2011-01-01

    Full Text Available Abstract We report on hybrid films based on ZnO/organic dye prepared by electrodeposition using tetrasulfonated copper phthalocyanines (TS-CuPc and Eosin-Y (EoY. Both the morphology and porosity of hybrid ZnO films are highly dependent on the type of dyes used in the synthesis. High photosensitivity was observed for ZnO/EoY films, while a very weak photoresponse was obtained for ZnO/TS-CuPc films. Despite a higher absorption coefficient of TS-CuPc than EoY, in ZnO/EoY hybrid films, the excited photoelectrons between the EoY levels can be extracted through ZnO, and the porosity of ZnO/EoY can also be controlled.

  7. Ultra-thin lithium micro-batteries. Performances and applications; Microaccumulateurs ultra minces au lithium. Performances et applications

    Energy Technology Data Exchange (ETDEWEB)

    Martin, M.; Terrat, J.P. [Hydromecanique et frottement (HEF), 42 - Andrezieux Boutheon (France); Levasseur, A.; Vinatier, P.; Meunier, G. [Centre National de la Recherche Scientifique (CNRS), 33 - Talence (France). Institut de Chimie de la Matiere Condensee et Physique de Bordeaux

    1996-12-31

    This short paper (abstract) describes the characteristics and performances of prototypes of ultra-thin lithium micro-batteries (thickness < 0.2 mm) which can be incorporated into microelectronic circuits. (J.S.)

  8. Ultra-thin lithium micro-batteries. Performances and applications; Microaccumulateurs ultra minces au lithium. Performances et applications

    Energy Technology Data Exchange (ETDEWEB)

    Martin, M; Terrat, J P [Hydromecanique et frottement (HEF), 42 - Andrezieux Boutheon (France); Levasseur, A; Vinatier, P; Meunier, G [Centre National de la Recherche Scientifique (CNRS), 33 - Talence (France). Institut de Chimie de la Matiere Condensee et Physique de Bordeaux

    1997-12-31

    This short paper (abstract) describes the characteristics and performances of prototypes of ultra-thin lithium micro-batteries (thickness < 0.2 mm) which can be incorporated into microelectronic circuits. (J.S.)

  9. Ultra-thin flexible polyimide neural probe embedded in a dissolvable maltose-coated microneedle

    International Nuclear Information System (INIS)

    Xiang, Zhuolin; Yen, Shih-Cheng; Zhang, Songsong; Lee, Chengkuo; Xue, Ning; Sun, Tao; Tsang, Wei Mong; Liao, Lun-De; Thakor, Nitish V

    2014-01-01

    The ultra-thin flexible polyimide neural probe can reduce the glial sheath growth on the probe body while its flexibility can minimize the micromotion between the probe and brain tissue. To provide sufficient stiffness for penetration purposes, we developed a drawing lithography technology for uniform maltose coating to make the maltose-coated polyimide neural probe become a stiff microneedle. The coating thicknesses under different temperature and the corresponding stiffness are studied. It has been proven that the coated maltose is dissolved by body fluids after implantation for a few seconds. Moreover, carbon nanotubes are coated on the neural probe recording electrodes to improve the charge delivery ability and reduce the impedance. Last but not least, the feasibility and recording characteristic of this ultra-thin polyimide neural probe embedded in a maltose-coated microneedle are further demonstrated by in vivo tests. (paper)

  10. Ultra-thin flexible polyimide neural probe embedded in a dissolvable maltose-coated microneedle

    Science.gov (United States)

    Xiang, Zhuolin; Yen, Shih-Cheng; Xue, Ning; Sun, Tao; Mong Tsang, Wei; Zhang, Songsong; Liao, Lun-De; Thakor, Nitish V.; Lee, Chengkuo

    2014-06-01

    The ultra-thin flexible polyimide neural probe can reduce the glial sheath growth on the probe body while its flexibility can minimize the micromotion between the probe and brain tissue. To provide sufficient stiffness for penetration purposes, we developed a drawing lithography technology for uniform maltose coating to make the maltose-coated polyimide neural probe become a stiff microneedle. The coating thicknesses under different temperature and the corresponding stiffness are studied. It has been proven that the coated maltose is dissolved by body fluids after implantation for a few seconds. Moreover, carbon nanotubes are coated on the neural probe recording electrodes to improve the charge delivery ability and reduce the impedance. Last but not least, the feasibility and recording characteristic of this ultra-thin polyimide neural probe embedded in a maltose-coated microneedle are further demonstrated by in vivo tests.

  11. Designable ultra-smooth ultra-thin solid-electrolyte interphases of three alkali metal anodes.

    Science.gov (United States)

    Gu, Yu; Wang, Wei-Wei; Li, Yi-Juan; Wu, Qi-Hui; Tang, Shuai; Yan, Jia-Wei; Zheng, Ming-Sen; Wu, De-Yin; Fan, Chun-Hai; Hu, Wei-Qiang; Chen, Zhao-Bin; Fang, Yuan; Zhang, Qing-Hong; Dong, Quan-Feng; Mao, Bing-Wei

    2018-04-09

    Dendrite growth of alkali metal anodes limited their lifetime for charge/discharge cycling. Here, we report near-perfect anodes of lithium, sodium, and potassium metals achieved by electrochemical polishing, which removes microscopic defects and creates ultra-smooth ultra-thin solid-electrolyte interphase layers at metal surfaces for providing a homogeneous environment. Precise characterizations by AFM force probing with corroborative in-depth XPS profile analysis reveal that the ultra-smooth ultra-thin solid-electrolyte interphase can be designed to have alternating inorganic-rich and organic-rich/mixed multi-layered structure, which offers mechanical property of coupled rigidity and elasticity. The polished metal anodes exhibit significantly enhanced cycling stability, specifically the lithium anodes can cycle for over 200 times at a real current density of 2 mA cm -2 with 100% depth of discharge. Our work illustrates that an ultra-smooth ultra-thin solid-electrolyte interphase may be robust enough to suppress dendrite growth and thus serve as an initial layer for further improved protection of alkali metal anodes.

  12. Research on precision grinding technology of large scale and ultra thin optics

    Science.gov (United States)

    Zhou, Lian; Wei, Qiancai; Li, Jie; Chen, Xianhua; Zhang, Qinghua

    2018-03-01

    The flatness and parallelism error of large scale and ultra thin optics have an important influence on the subsequent polishing efficiency and accuracy. In order to realize the high precision grinding of those ductile elements, the low deformation vacuum chuck was designed first, which was used for clamping the optics with high supporting rigidity in the full aperture. Then the optics was planar grinded under vacuum adsorption. After machining, the vacuum system was turned off. The form error of optics was on-machine measured using displacement sensor after elastic restitution. The flatness would be convergenced with high accuracy by compensation machining, whose trajectories were integrated with the measurement result. For purpose of getting high parallelism, the optics was turned over and compensation grinded using the form error of vacuum chuck. Finally, the grinding experiment of large scale and ultra thin fused silica optics with aperture of 430mm×430mm×10mm was performed. The best P-V flatness of optics was below 3 μm, and parallelism was below 3 ″. This machining technique has applied in batch grinding of large scale and ultra thin optics.

  13. Ultra-thin Oxide Membranes: Synthesis and Carrier Transport

    Science.gov (United States)

    Sim, Jai Sung

    Self-supported freestanding membranes are films that are devoid of any underlying supporting layers. The key advantage of such structures is that, due to the lack of substrate effects - both mechanical and chemical, the true native properties of the material can be probed. This is crucial since many of the studies done on materials that are used as freestanding membranes are done as films clamped to substrates or in the bulk form. This thesis focuses on the synthesis and fabrication as well as electrical studies of free standing ultrathin controllable thin film deposition process. Taking things a step further, to electrically probe these membranes required design of complex device architecture and extensive optimization of nano-fabrication processes. The challenges and optimized fabrication method of such membranes are demonstrated. Three materials are probed in this study, VO2, TiO2, and CeO2. VO2 for understanding structural considerations for electronic phase change and nature of ionic liquid gating, TiO2 and CeO2 for understanding surface conduction properties and surface chemistry. The VO2 study shows shift in metal-insulator transition (MIT) temperature arising from stress relaxation and opening of the hysteresis. The ionic liquid gating studies showed reversible modulation of channel resistance and allowed distinguishing bulk process from the surface effects. Comparing the ionic liquid gating experiments to hydrogen doping experiments illustrated that ionic liquid gating can be a surface limited electrostatic effect, if the critical voltage threshold is not exceeded. TiO2 study shows creation of non-stoichiometric forms under ion milling. Utilizing focused ion beam milling, thin membranes of Ti xOy of 100-300 nm thickness have been created. TEM studies indicated polycrystallinity and presence of twins in the FIB-milled nanowalls. Compositional analysis in the transmission electron microscope also showed reduced content of oxygen, confirming non

  14. Multispectral surface plasmon resonance approach for ultra-thin silver layer characterization: Application to top-emitting OLED cathode

    Science.gov (United States)

    Taverne, S.; Caron, B.; Gétin, S.; Lartigue, O.; Lopez, C.; Meunier-Della-Gatta, S.; Gorge, V.; Reymermier, M.; Racine, B.; Maindron, T.; Quesnel, E.

    2018-01-01

    While dielectric/metal/dielectric (DMD) multilayer thin films have raised considerable interest as transparent and conductive electrodes in various optoelectronic devices, the knowledge of optical characteristics of thin metallic layers integrated in such structures is still rather approximate. The multispectral surface plasmon resonance characterization approach described in this work precisely aims at providing a rigorous methodology able to accurately determine the optical constants of ultra-thin metallic films. As a practical example, the refractive index and extinction dispersion curves of 8 to 25 nm-thick silver layers have been investigated. As a result, their extreme dependence on the layer thickness is highlighted, in particular in a thickness range close to the critical threshold value (˜10 nm) where the silver film becomes continuous and its electrical conductance/optical transmittance ratio particularly interesting. To check the validity of the revisited Ag layers constant dispersion curves deduced from this study, they were introduced into a commercial optical model software to simulate the behavior of various optoelectronic building blocks from the simplest ones (DMD electrodes) to much more complex structures [full organic light emitting device (OLED) stacks]. As a result, a much better prediction of the emission spectrum profile as well as the angular emission pattern of top-emitting OLEDs is obtained. On this basis, it is also shown how a redesign of the top encapsulation thin film of OLEDs is necessary to better take benefit from the advanced DMD electrode. These results should particularly interest the micro-OLED display field where bright and directive single color pixel emission is required.

  15. Development of thin-film Si HYBRID solar module

    Energy Technology Data Exchange (ETDEWEB)

    Nakajima, Akihiko; Gotoh, Masahiro; Sawada, Toru; Fukuda, Susumu; Yoshimi, Masashi; Yamamoto, Kenji; Nomura, Takuji [Kaneka Corporation, 2-1-1, Hieitsuji, Otsu, Shiga 520-0104 (Japan)

    2009-06-15

    The device current-voltage (I-V) characteristics of thin-film silicon stacked tandem solar modules (HYBRID modules), consisting of a hydrogenated amorphous silicon (a-Si:H) cell and a thin-film crystalline silicon solar cell ({mu}c-Si), have been investigated under various spectral irradiance distributions. The performance of the HYBRID module varied periodically in natural sunlight due to the current-limiting property of the HYBRID module and the environmental effects. The behavior based on the current-limiting property was demonstrated by the modelling of the I-V curves using the linear interpolation method for each component cell. The improvement of the performance for the HYBRID module in natural sunlight will also be discussed from the viewpoint of the device design of the component cells. (author)

  16. Questing and the application for silicon based ternary compound within ultra-thin layer of SIS intermediate region

    International Nuclear Information System (INIS)

    Chen, Shumin; Gao, Ming; Wan, Yazhou; Du, Huiwei; Li, Yong; Ma, Zhongquan

    2016-01-01

    Highlights: • A new kind of functional material with plasticity of dielectric was obtained. • Powerful characterization methods was exploited to determine this ultra-thin layer. • The electronic structures and properties of this intermediate layer were analyzed. • A potential application of this structure were investigated. - Abstract: A silicon based ternary compound was supposed to be solid synthesized with In, Si and O elements by magnetron sputtering of indium tin oxide target (ITO) onto crystal silicon substrate at 250 °C. To make clear the configuration of the intermediate region, a potential method to obtain the chemical bonding of Si with other existing elements was exploited by X-ray photoelectron spectroscopy (XPS) instrument combined with other assisted techniques. The phase composition and solid structure of the interfacial region between ITO and Si substrate were investigated by X-ray diffraction (XRD) and high resolution cross sectional transmission electron microscope (HR-TEM). A photovoltaic device with structure of Al/Ag/ITO/SiOx/p-Si/Al was assembled by depositing ITO films onto the p-Si substrate by using magnetron sputtering. The new matter has been assumed to be a buffer layer for semiconductor-insulator-semiconductor (SIS) photovoltaic device and plays critical role for the promotion of optoelectronic conversion performance from the view point of device physics.

  17. Uncorrelated multiple conductive filament nucleation and rupture in ultra-thin high-κ dielectric based resistive random access memory

    KAUST Repository

    Wu, Xing

    2011-08-29

    Resistive switching in transition metal oxides could form the basis for next-generation non-volatile memory (NVM). It has been reported that the current in the high-conductivity state of several technologically relevant oxide materials flows through localized filaments, but these filaments have been characterized only individually, limiting our understanding of the possibility of multiple conductive filaments nucleation and rupture and the correlation kinetics of their evolution. In this study, direct visualization of uncorrelated multiple conductive filaments in ultra-thin HfO2-based high-κ dielectricresistive random access memory (RRAM) device has been achieved by high-resolution transmission electron microscopy (HRTEM), along with electron energy loss spectroscopy(EELS), for nanoscale chemical analysis. The locations of these multiple filaments are found to be spatially uncorrelated. The evolution of these microstructural changes and chemical properties of these filaments will provide a fundamental understanding of the switching mechanism for RRAM in thin oxide films and pave way for the investigation into improving the stability and scalability of switching memory devices.

  18. Thin layer activation and ultra thin layer activation: two complementary techniques for wear and corrosion studies in various fields

    International Nuclear Information System (INIS)

    Sauvage, T.; Vincent, L.; Blondiaux, G.

    2002-01-01

    Thin layer activation (TLA) is widely used since more than 25 years to study surface wear or corrosion. This well known technique uses most of the time charged particles activation, which gives sensitivity in the range of the micrometer, except when the fluid mode of detection is utilized. In this case application of the method is limited to phenomena where we have transport of radioactive fragments to detection point. The main disadvantage of this procedure is the error due to trapping phenomena between the wear or corrosion point and detection setup. So the ultra thin layer activation (UTLA) has been developed to get nanometric sensitivity without using any fluid for radioactivity transportation, which is the main source of error of the TLA technique. In this paper we shall briefly describe the TLA technique and the most important fields of application. Then we shall emphasise on UTLA with a presentation of the principle of the method and actual running of application. The main problem concerning UTLA is calibration which requires the use of thin films (usually 10 to 100 nanometers) deposited on substrate. This process is time consuming and we shall demonstrate how running software developed in the lab can solve it. We shall finish the presentation by giving some potential application of the technique in various fields. (authors)

  19. Questing and the application for silicon based ternary compound within ultra-thin layer of SIS intermediate region

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shumin; Gao, Ming; Wan, Yazhou; Du, Huiwei; Li, Yong [SHU-SolarE R& D Lab, Department of Physics, Shanghai University, Shanghai 200444 (China); Ma, Zhongquan, E-mail: zqma@shu.edu.cn [SHU-SolarE R& D Lab, Department of Physics, Shanghai University, Shanghai 200444 (China); Instrumental Analysis & Research Center, Shanghai University, Shanghai 200444 (China)

    2016-12-01

    Highlights: • A new kind of functional material with plasticity of dielectric was obtained. • Powerful characterization methods was exploited to determine this ultra-thin layer. • The electronic structures and properties of this intermediate layer were analyzed. • A potential application of this structure were investigated. - Abstract: A silicon based ternary compound was supposed to be solid synthesized with In, Si and O elements by magnetron sputtering of indium tin oxide target (ITO) onto crystal silicon substrate at 250 °C. To make clear the configuration of the intermediate region, a potential method to obtain the chemical bonding of Si with other existing elements was exploited by X-ray photoelectron spectroscopy (XPS) instrument combined with other assisted techniques. The phase composition and solid structure of the interfacial region between ITO and Si substrate were investigated by X-ray diffraction (XRD) and high resolution cross sectional transmission electron microscope (HR-TEM). A photovoltaic device with structure of Al/Ag/ITO/SiOx/p-Si/Al was assembled by depositing ITO films onto the p-Si substrate by using magnetron sputtering. The new matter has been assumed to be a buffer layer for semiconductor-insulator-semiconductor (SIS) photovoltaic device and plays critical role for the promotion of optoelectronic conversion performance from the view point of device physics.

  20. A tunable hybrid metamaterial absorber based on vanadium oxide films

    International Nuclear Information System (INIS)

    Wen Qiye; Zhang Huaiwu; Yang Qinghui; Long Yang; Jing Yulan; Lin Yuan; Chen Zhi; Zhang Peixin

    2012-01-01

    A tunable hybrid metamaterial absorber (MA) in the microwave band was designed, fabricated and characterized. The hybrid MA was realized by incorporating a VO 2 film into the conventional resonant MA. By thermally triggering the insulator-metal phase transition of the VO 2 film, the impedance match condition was broken and a deep amplitude modulation of about 63.3% to the electromagnetic wave absorption was achieved. A moderate blue-shift of the resonance frequency was observed which is promising for practical applications. This VO 2 -based MA exhibits many advantages such as strong tunability, frequency agility, simple fabrication and ease of scaling to the terahertz band. (paper)

  1. Development of Cutaneous Bioadhesive Ureasil-Polyether Hybrid Films

    Directory of Open Access Journals (Sweden)

    João Augusto Oshiro Junior

    2015-01-01

    Full Text Available The hydrolysis and condensation reactions involved in synthesis of ureasil-polyether films influence the film formation time and the number of chemical groups able to form hydrogen bonds, responsible for the bioadhesion, with the biological substrate. The objective of this work was to study the influence of the use of an acid catalyst (hydrochloric acid and a basic catalyst (ammonium fluoride in the hydrolysis and condensation reactions on the time formation and bioadhesion of ureasil-polyether films. The toxicity of the films was evaluated. The MTT assay has shown cell viability of human skin keratinocytes higher than 70% of all analyzed materials suggesting low cytotoxicity. The bioadhesion of the films is strongly dependent on the viscosity and hydrophilic/hydrophobic balance of the polyether chains used to synthetize the hybrid molecules. The use of acid catalyst promotes the formation of less viscous films with higher bioadhesion. The hybrids formed by more hydrophilic PEO chains are more bioadherent, since they can interact more efficiently with the water present in the stratum corneum increasing the bioadhesion. Due to their low toxicity and high bioadhesion, the ureasil-PEO films obtained by using HCl as catalyst agent are good candidates for application to the skin as bioadhesive films.

  2. High performance organic field-effect transistors with ultra-thin HfO2 gate insulator deposited directly onto the organic semiconductor

    International Nuclear Information System (INIS)

    Ono, S.; Häusermann, R.; Chiba, D.; Shimamura, K.; Ono, T.; Batlogg, B.

    2014-01-01

    We have produced stable organic field-effect transistors (OFETs) with an ultra-thin HfO 2 gate insulator deposited directly on top of rubrene single crystals by atomic layer deposition (ALD). We find that ALD is a gentle deposition process to grow thin films without damaging rubrene single crystals, as results these devices have a negligibly small threshold voltage and are very stable against gate-bias-stress, and the mobility exceeds 1 cm 2 /V s. Moreover, the devices show very little degradation even when kept in air for more than 2 months. These results demonstrate thin HfO 2 layers deposited by ALD to be well suited as high capacitance gate dielectrics in OFETs operating at small gate voltage. In addition, the dielectric layer acts as an effective passivation layer to protect the organic semiconductor

  3. Culturing of primary rat neurons and glia on ultra-thin parylene-C

    International Nuclear Information System (INIS)

    Unsworth, C.P.; Delivopoulos, E.; Murray, A.F.

    2010-01-01

    Full text: In this article, we will describe how we have successfully cultured dissociated embryonic cortical neurons and glia from the postnatal rat hippocampus on extremely thin layers (up to 10 nm) of Parylene-C on a silicon dioxide substrate. Silicon wafers were oxidised, deposited with the biomaterial, Parylene-C, photo-lithographically patterned and plasma etched to produce chips that consisted of lines of Paryl ene-C with varying widths, thickness and lengths. The chips produced were then immersed in Horse Serum and plated with the cells. Ratios of Neurons; Glia; Cell Body were measured on, adjacent to and away from the Parylene-C. Our initial results show how these ratios remained roughly constant for ultra-thin Parylene-C thicknesses of 10 nm as compared to a benchmark thickness of 100 nm (where such cells are known to grow well). Thus, our findings demonstrate that it is possible to culture primary rat neurons and glia to practically cell membrane thicknesses of Parylene-C. Being able to culture cells on such ultra thin levels of Parylene-C will open up the possibility to develop Multi-Electrode Arrays (MEA) that can capacitively couple embedded electrodes through the parylene to the cells on its surface. Thus, providing a neat, insulated passive electrode. Only the ultra-thin thicknesses of Parylene demonstrated here would allow for the rea isation of such a technology. Hence, the outcome of this work, will be of great interest to the Neuroengineering and the Multi-Electrode Array (MEA) community, as an alternative material for the fabric tion of passive electrodes, used in capacitive coupling mode.

  4. Ultra-thin smart acoustic metasurface for low-frequency sound insulation

    Science.gov (United States)

    Zhang, Hao; Xiao, Yong; Wen, Jihong; Yu, Dianlong; Wen, Xisen

    2016-04-01

    Insulating low-frequency sound is a conventional challenge due to the high areal mass required by mass law. In this letter, we propose a smart acoustic metasurface consisting of an ultra-thin aluminum foil bonded with piezoelectric resonators. Numerical and experimental results show that the metasurface can break the conventional mass law of sound insulation by 30 dB in the low frequency regime (sound insulation performance is attributed to the infinite effective dynamic mass density produced by the smart resonators. It is also demonstrated that the excellent sound insulation property can be conveniently tuned by simply adjusting the external circuits instead of modifying the structure of the metasurface.

  5. Role of interlayer coupling in ultra thin MoS2

    KAUST Repository

    Cheng, Yingchun

    2012-01-01

    The effects of interlayer coupling on the vibrational and electronic properties of ultra thin MoS 2 were studied by ab initio calculations. For smaller slab thickness, the interlayer distance is significantly elongated because of reduced interlayer coupling. This explains the anomalous thickness dependence of the lattice vibrations observed by Lee et al. (ACS Nano, 2010, 4, 2695). The absence of interlayer coupling in mono-layer MoS 2 induces a transition from direct to indirect band gap behaviour. Our results demonstrate a strong interplay between the intralayer chemical bonding and the interlayer van-der-Waals interaction. This journal is © 2012 The Royal Society of Chemistry.

  6. Nanostructured hybrid films containing nanophosphor: Fabrication and electronic spectral properties

    Energy Technology Data Exchange (ETDEWEB)

    Camacho, S.A. [Instituto de Biociencias, Letras e Ciencias Exatas, UNESP - Univ Estadual Paulista, Rua Cristovao Colombo, 2265, 15054-000 Sao Jose do Rio Preto, SP (Brazil); Aoki, P.H.B.; Constantino, C.J.L. [Faculdade de Ciencias e Tecnologia, UNESP - Univ Estadual Paulista, Rua Roberto Simonsen, 305, 19060-900 Presidente Prudente, SP (Brazil); Aroca, R.F. [Materials and Surface Science Group, University of Windsor, Windsor, Ont., Canada N9B3P4 (Canada); Pires, A.M., E-mail: anapires@fct.unesp.br [Faculdade de Ciencias e Tecnologia, UNESP - Univ Estadual Paulista, Rua Roberto Simonsen, 305, 19060-900 Presidente Prudente, SP (Brazil)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer Hybrid film containing the cationic polyelectrolyte PAH and Y{sub 2}O{sub 3}: Er, Yb nanophosphor. Black-Right-Pointing-Pointer LbL film growth was monitored by absorbance x concentration in UV-Vis absorption. Black-Right-Pointing-Pointer FTIR indicated existence of secondary interactions between PAH - nanophosphor layers. Black-Right-Pointing-Pointer The morphology and the spatial distribution of the LbL film were analyzed by Raman. Black-Right-Pointing-Pointer We observed intense electronic emission lines from doping ions in the micro-Raman. - Abstract: The intensive research of the optical properties of rare-earth ions is due to the high quantum efficiency of their emission, very narrow bands, and excellent fluorescence monochromaticity. The photoluminescence data presented here show that the nanophosphor remains a green emitter in Layer-by-Layer (LbL) films leading to potential application in optical devices or biological labeling. The LbL technique, an established method for thin film fabrication with molecular architecture control, is used in the manufacture of a hybrid film containing the cationic polyelectrolyte poly (allylamine hydrochloride) (PAH) and Y{sub 2}O{sub 3}: Er, Yb nanophosphor. The spectroscopic properties of this luminescent nanomaterial are extracted from the spectral data of the powder, cast film and LbL films. The growth of the LbL film was monitored by absorbance versus concentration plots in ultraviolet-visible (UV-Vis) absorption spectroscopy. The presence of both PAH and nanophosphor in the LbL film was confirmed by Fourier transform infrared (FTIR) absorption spectroscopy. The FTIR data also ruled out the existence of chemical interactions between the PAH and nanophosphor layers, which means that secondary interactions (like Van der Waals forces) might be the driving forces for LbL film growth. The morphology and the spatial distribution of the LbL film components along the film surface were

  7. Low temperature synthesis of Mo2C/W2C superlattices via ultra-thin modulated reactants

    International Nuclear Information System (INIS)

    Johnson, C.D.; Johnson, D.C.

    1996-01-01

    The authors report here a synthesis method of preparing carbide superlattices using ultra-thin modulated reactants. Initial investigations into the synthesis of the binary systems, Mo 2 C and W 2 C using ultra-thin modulated reactants revealed that both can be formed at relatively low temperatures (500 and 600 C respectively). DSC and XRD data suggested a two step reaction pathway involving interdiffusion of the initial modulated reactant followed by crystallization of the final product, if the modulation length is on the order of 10 angstrom. This information was used to form Mo 2 C/W 2 C superlattices using the structure of the ultra-thin modulated reactant to control the final superlattice period. Relatively large superlattice modulations were kinetically trapped by having several repeat units of each binary within the total repeat of the initial reactant. DSC and XRD data again are consistent with a two step reaction pathway leading to the formation of carbide superlattices

  8. Nanometric hybrid films of xanthan and magnetite

    International Nuclear Information System (INIS)

    Pereira, Edla M.A.; Silva, Anielle M.; Petri, Denise F.S.

    2011-01-01

    Magnetite nanoparticles (NMM) were synthesized by co-characterized by means of X-ray diffraction, infrared spectroscopy and potentiometric titration. Xanthan thin films and NMM were deposited alternately onto Si wafers. The attachment of first xanthan layer onto Si wafer was obtained in the presence of Ca 2+ 1 mM and at pH 10. Under these conditions calcium ions interact electrostatically with both silanol groups and xanthan carboxylate groups, yielding stable xanthan (1.5 ± 0.5) nm thick films. The deposition of NMM was forced by applying a magnetic field set under the sample. The following bilayers were formed by 'layer-by-layer' electrostatic process and magnetic field action. The bilayers formation was monitored by the variation in the ellipsometric angles values, Δ e ψ, and atomic force microscopy. (author)

  9. GaAs detectors with an ultra-thin Schottky contact for spectrometry of charged particles

    Energy Technology Data Exchange (ETDEWEB)

    Chernykh, S.V., E-mail: chsv_84@mail.ru [National University of Science and Technology “MISIS”, Moscow (Russian Federation); Research Institute of Experimental and Theoretical Physics, Almaty (Kazakhstan); Chernykh, A.V. [National University of Science and Technology “MISIS”, Moscow (Russian Federation); Didenko, S.I.; Baryshnikov, F.M. [National University of Science and Technology “MISIS”, Moscow (Russian Federation); Research Institute of Experimental and Theoretical Physics, Almaty (Kazakhstan); Burtebayev, N. [Research Institute of Experimental and Theoretical Physics, Almaty (Kazakhstan); Institute of Nuclear Physics, Almaty (Kazakhstan); Britvich, G.I. [Institute of High Energy Physics, Protvino, Moscow region (Russian Federation); Chubenko, A.P. [Research Institute of Experimental and Theoretical Physics, Almaty (Kazakhstan); P.N. Lebedev Physical Institute of the Russian Academy of Sciences, Moscow (Russian Federation); Guly, V.G.; Glybin, Yu.N. [LLC “SNIIP Plus”, Moscow (Russian Federation); Zholdybayev, T.K.; Burtebayeva, J.T.; Nassurlla, M. [Research Institute of Experimental and Theoretical Physics, Almaty (Kazakhstan); Institute of Nuclear Physics, Almaty (Kazakhstan)

    2017-02-11

    For the first time, samples of particle detectors based on high-purity GaAs epilayers with an active area of 25 and 80 mm{sup 2} and an ultra-thin Pt Schottky barrier were fabricated for use in the spectrometry of charged particles and their operating characteristics were studied. The obtained FWHM of 14.2 (for 25 mm{sup 2} detector) and 15.5 keV (for 80 mm{sup 2} detector) on the 5.499 MeV line of {sup 238}Pu is at the level of silicon spectrometric detectors. It was found that the main component that determines the energy resolution of the detector is a fluctuation in the number of collected electron–hole pairs. This allows us to state that the obtained energy resolution is close to the limit for VPE GaAs. - Highlights: • VPE GaAs particle detectors with an active area of 25 and 80 mm{sup 2} were fabricated. • 120 Å ultra-thin Pt Schottky barrier was used as a rectifying contact. • The obtained FWHM of 14.2 keV ({sup 238}Pu) is at the level of Si spectrometric detectors. • Various components of the total energy resolution were analyzed. • It was shown that obtained energy resolution is close to its limit for VPE GaAs.

  10. Performance enhancement in organic photovoltaic solar cells using iridium (Ir) ultra-thin surface modifier (USM)

    Science.gov (United States)

    Pandey, Rina; Lim, Ju Won; Kim, Jung Hyuk; Angadi, Basavaraj; Choi, Ji Won; Choi, Won Kook

    2018-06-01

    In this study, Iridium (Ir) metallic layer as an ultra-thin surface modifier (USM) was deposited on ITO coated glass substrate using radio frequency magnetron sputtering for improving the photo-conversion efficiency of organic photovoltaic cells. Ultra-thin Ir acts as a surface modifier replacing the conventional hole transport layer (HTL) PEDOT:PSS in organic photovoltaic (OPV) cells with two different active layers P3HT:PC60BM and PTB7:PC70BM. The Ir USM (1.0 nm) coated on ITO glass substrate showed transmittance of 84.1% and work function of >5.0 eV, which is higher than that of ITO (4.5-4.7 eV). The OPV cells with Ir USM (1.0 nm) exhibits increased power conversion efficiency of 3.70% (for P3HT:PC60BM active layer) and 7.28% (for PTB7:PC70BM active layer) under 100 mW/cm2 illumination (AM 1.5G) which are higher than those of 3.26% and 6.95% for the same OPV cells but with PEDOT:PSS as HTL instead of Ir USM. The results reveal that the chemically stable Ir USM layer could be used as an alternative material for PEDOT:PSS in organic photovoltaic cells.

  11. Towards ultra-thin plasmonic silicon wafer solar cells with minimized efficiency loss.

    Science.gov (United States)

    Zhang, Yinan; Stokes, Nicholas; Jia, Baohua; Fan, Shanhui; Gu, Min

    2014-05-13

    The cost-effectiveness of market-dominating silicon wafer solar cells plays a key role in determining the competiveness of solar energy with other exhaustible energy sources. Reducing the silicon wafer thickness at a minimized efficiency loss represents a mainstream trend in increasing the cost-effectiveness of wafer-based solar cells. In this paper we demonstrate that, using the advanced light trapping strategy with a properly designed nanoparticle architecture, the wafer thickness can be dramatically reduced to only around 1/10 of the current thickness (180 μm) without any solar cell efficiency loss at 18.2%. Nanoparticle integrated ultra-thin solar cells with only 3% of the current wafer thickness can potentially achieve 15.3% efficiency combining the absorption enhancement with the benefit of thinner wafer induced open circuit voltage increase. This represents a 97% material saving with only 15% relative efficiency loss. These results demonstrate the feasibility and prospect of achieving high-efficiency ultra-thin silicon wafer cells with plasmonic light trapping.

  12. Ultra-thin distributed Bragg reflectors via stacked single-crystal silicon nanomembranes

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Minkyu; Seo, Jung-Hun; Lee, Jaeseong; Mi, Hongyi; Kim, Munho; Ma, Zhenqiang, E-mail: mazq@engr.wisc.edu [Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Zhao, Deyin; Zhou, Weidong [Nanophotonics Lab, Department of Electrical Engineering, University of Texas at Arlington, Arlington, Texas 76019 (United States); Yin, Xin; Wang, Xudong [Department of Material Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

    2015-05-04

    In this paper, we report ultra-thin distributed Bragg reflectors (DBRs) via stacked single-crystal silicon (Si) nanomembranes (NMs). Mesh hole-free single-crystal Si NMs were released from a Si-on-insulator substrate and transferred to quartz and Si substrates. Thermal oxidation was applied to the transferred Si NM to form high-quality SiO{sub 2} and thus a Si/SiO{sub 2} pair with uniform and precisely controlled thicknesses. The Si/SiO{sub 2} layers, as smooth as epitaxial grown layers, minimize scattering loss at the interface and in between the layers. As a result, a reflection of 99.8% at the wavelength range from 1350 nm to 1650 nm can be measured from a 2.5-pair DBR on a quartz substrate and 3-pair DBR on a Si substrate with thickness of 0.87 μm and 1.14 μm, respectively. The high reflection, ultra-thin DBRs developed here, which can be applied to almost any devices and materials, holds potential for application in high performance optoelectronic devices and photonics applications.

  13. Breakthrough to Non-Vacuum Deposition of Single-Crystal, Ultra-Thin, Homogeneous Nanoparticle Layers: A Better Alternative to Chemical Bath Deposition and Atomic Layer Deposition

    Directory of Open Access Journals (Sweden)

    Yu-Kuang Liao

    2017-04-01

    Full Text Available Most thin-film techniques require a multiple vacuum process, and cannot produce high-coverage continuous thin films with the thickness of a few nanometers on rough surfaces. We present a new ”paradigm shift” non-vacuum process to deposit high-quality, ultra-thin, single-crystal layers of coalesced sulfide nanoparticles (NPs with controllable thickness down to a few nanometers, based on thermal decomposition. This provides high-coverage, homogeneous thickness, and large-area deposition over a rough surface, with little material loss or liquid chemical waste, and deposition rates of 10 nm/min. This technique can potentially replace conventional thin-film deposition methods, such as atomic layer deposition (ALD and chemical bath deposition (CBD as used by the Cu(In,GaSe2 (CIGS thin-film solar cell industry for decades. We demonstrate 32% improvement of CIGS thin-film solar cell efficiency in comparison to reference devices prepared by conventional CBD deposition method by depositing the ZnS NPs buffer layer using the new process. The new ZnS NPs layer allows reduction of an intrinsic ZnO layer, which can lead to severe shunt leakage in case of a CBD buffer layer. This leads to a 65% relative efficiency increase.

  14. In situ synthesis of silver benzene-dithiolate hybrid films

    Energy Technology Data Exchange (ETDEWEB)

    Brenier, Roger, E-mail: roger.brenier@univ-lyon1.fr [Institut Lumière Matière, UMR 5306, Université Lyon 1-CNRS, Université de Lyon, Domaine Scientifique de La Doua, Batiment Kastler, 10 rue Ada Byron, 69622 Villeurbanne, Cedex (France); Piednoir, Agnès, E-mail: agnes.piednoir@univ-lyon1.fr [Institut Lumière Matière, UMR 5306, Université Lyon 1-CNRS, Université de Lyon, Domaine Scientifique de La Doua, Batiment Kastler, 10 rue Ada Byron, 69622 Villeurbanne, Cedex (France); Bertorelle, Franck, E-mail: franck.bertorelle@univ-lyon1.fr [Institut Lumière Matière, UMR 5306, Université Lyon 1-CNRS, Université de Lyon, Domaine Scientifique de La Doua, Batiment Kastler, 10 rue Ada Byron, 69622 Villeurbanne, Cedex (France); Penuelas, José, E-mail: jose.penuelas@ec-lyon.fr [Université de Lyon, Institut des Nanotechnologies de Lyon, Ecole Centrale de Lyon, CNRS, UMR 5270, 36 rue Guy de Collongues, F69134 Ecully (France); Grenet, Geneviève, E-mail: genevieve.grenet@ec-lyon.fr [Université de Lyon, Institut des Nanotechnologies de Lyon, Ecole Centrale de Lyon, CNRS, UMR 5270, 36 rue Guy de Collongues, F69134 Ecully (France)

    2016-02-01

    In this article, a method for in situ synthesis of silver benzene-dithiolate hybrid films is presented. Silver nanoparticles, generated on ZrO{sub 2} films, are transformed into silver benzene 1,4-dithiolate or, partially, into silver benzene 1,2-dithiolate after sample immersion in the corresponding thiol solutions. These transformations occur at room temperature owing to the catalytic action of ZrO{sub 2}. It is also shown that TiO{sub 2} in place of ZrO{sub 2} is very efficient, both for the catalytic generation of silver nanoparticles and for their further transformation in benzene 1,4-dithiolate compound. This latter semiconductor has an optical bandgap of about 3 eV and the film is made of touching nanoparticles in an amorphous state. Our work has potential applications in the electronic and photovoltaic fields. - Highlights: • A method for in situ synthesis of silver benzene-dithiolate hybrid semiconductor films is presented. • Silver nanoparticles are, first, generated on ZrO{sub 2} or on TiO{sub 2} coated silica substrates. • The samples are immersed in benzene dithiol solution for two days at room temperature. • During the immersion, the silver nanoparticles are transformed into silver benzene dithiolate. • The silver benzene dithiolate film is made of amorphous nanoparticles with a banbgap of 3 eV.

  15. Electronic structure evolution in doping of fullerene (C{sub 60}) by ultra-thin layer molybdenum trioxide

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chenggong; Wang, Congcong; Kauppi, John [Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627 (United States); Liu, Xiaoliang [Institute for Super-microstructure and Ultrafast Process in Advanced Materials (ISUPAM), Central South University, Changsha, Hunan 410083 (China); Gao, Yongli, E-mail: ygao@pas.rochester.edu [Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627 (United States); Institute for Super-microstructure and Ultrafast Process in Advanced Materials (ISUPAM), Central South University, Changsha, Hunan 410083 (China)

    2015-08-28

    Ultra-thin layer molybdenum oxide doping of fullerene has been investigated using ultraviolet photoemission spectroscopy (UPS) and X-ray photoemission spectroscopy (XPS). The highest occupied molecular orbital (HOMO) can be observed directly with UPS. It is observed that the Fermi level position in fullerene is modified by ultra-thin-layer molybdenum oxide doping, and the HOMO onset is shifted to less than 1.3 eV below the Fermi level. The XPS results indicate that charge transfer was observed from the C{sub 60} to MoO{sub x} and Mo{sup 6+} oxides is the basis as hole dopants.

  16. Ultra-thin silicon (UTSi) on insulator CMOS transceiver and time-division multiplexed switch chips for smart pixel integration

    Science.gov (United States)

    Zhang, Liping; Sawchuk, Alexander A.

    2001-12-01

    We describe the design, fabrication and functionality of two different 0.5 micron CMOS optoelectronic integrated circuit (OEIC) chips based on the Peregrine Semiconductor Ultra-Thin Silicon on insulator technology. The Peregrine UTSi silicon- on-sapphire (SOS) technology is a member of the silicon-on- insulator (SOI) family. The low-loss synthetic sapphire substrate is optically transparent and has good thermal conductivity and coefficient of thermal expansion properties, which meet the requirements for flip-chip bonding of VCSELs and other optoelectronic input-output components. One chip contains transceiver and network components, including four channel high-speed CMOS transceiver modules, pseudo-random bit stream (PRBS) generators, a voltage controlled oscillator (VCO) and other test circuits. The transceiver chips can operate in both self-testing mode and networking mode. An on- chip clock and true-single-phase-clock (TSPC) D-flip-flop have been designed to generate a PRBS at over 2.5 Gb/s for the high-speed transceiver arrays to operate in self-testing mode. In the networking mode, an even number of transceiver chips forms a ring network through free-space or fiber ribbon interconnections. The second chip contains four channel optical time-division multiplex (TDM) switches, optical transceiver arrays, an active pixel detector and additional test devices. The eventual applications of these chips will require monolithic OEICs with integrated optical input and output. After fabrication and testing, the CMOS transceiver array dies will be packaged with 850 nm vertical cavity surface emitting lasers (VCSELs), and metal-semiconductor- metal (MSM) or GaAs p-i-n detector die arrays to achieve high- speed optical interconnections. The hybrid technique could be either wire bonding or flip-chip bonding of the CMOS SOS smart-pixel arrays with arrays of VCSELs and photodetectors onto an optoelectronic chip carrier as a multi-chip module (MCM).

  17. UV light induced insulator-metal transition in ultra-thin ZnO/TiO{sub x} stacked layer grown by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Saha, D., E-mail: sahaphys@gmail.com, E-mail: pmisra@rrcat.gov.in; Misra, P., E-mail: sahaphys@gmail.com, E-mail: pmisra@rrcat.gov.in; Joshi, M. P.; Kukreja, L. M. [Laser Materials Processing Division, Raja Ramanna Centre for Advanced Technology, Indore 452 013 (India)

    2016-08-28

    In the present study, atomic layer deposition has been used to grow a series of Ti incorporated ZnO thin films by vertically stacking different numbers (n = 1–7) of ZnO/TiO{sub x} layers on (0001) sapphire substrates. The effects of defect states mediated chemisorption of O{sub 2} and/OH groups on the electrical properties of these films have been investigated by illuminating the samples under UV light inside a high vacuum optical cryostat. The ultra-thin film having one stacked layer (n = 1) did not show any change in its electrical resistance upon UV light exposure. On the contrary, marginal drop in the electrical resistivity was measured for the samples with n ≥ 3. Most surprisingly, the sample with n = 2 (thickness ∼ 12 nm) showed an insulator to metal transition upon UV light exposure. The temperature dependent electrical resistivity measurement on the as grown film (n = 2) showed insulating behaviour, i.e., diverging resistivity on extrapolation to T→ 0 K. However, upon UV light exposure, it transformed to a metallic state, i.e., finite resistivity at T → 0 K. Such an insulator-metal transition plausibly arises due to the de-trapping of conduction electrons from the surface defect sites which resulted in an upward shift of the Fermi level above the mobility edge. The low-temperature electron transport properties on the insulating film (n = 2) were investigated by a combined study of zero field electrical resistivity ρ(T) and magnetoresistance (MR) measurements. The observed negative MR was found to be in good agreement with the magnetic field induced suppression of quantum interference between forward-going paths of tunnelling electrons. Both ρ(T) and MR measurements provided strong evidence for the Efros-Shklovskii type variable range hopping conduction in the low-temperature (≤40 K) regime. Such studies on electron transport in ultra-thin n-type doped ZnO films are crucial to achieve optimum functionality

  18. High-frequency electromagnetic properties of soft magnetic metal-polyimide hybrid thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sang Woo [Nano-Materials Research Center, Korea Institute of Science and Technology, 39-1 Haweoulgog-dong, Sungbuk-gu, Seoul 136-791 (Korea, Republic of)]. E-mail: swkim@kist.re.kr; Yoon, Chong S. [Division of Advanced Materials Science, Hanyang University, Seoul 133-791 (Korea, Republic of)

    2007-09-15

    Although there are a lot of demands for suppression of unwanted high-frequency electromagnetic noise in highly integrated electronic devices such as mobile phones and notebook computers, electromagnetic thin films that effectively work in the high-frequency range have still been underdeveloped. Soft magnetic metal-polyimide (PI) hybrid films with high electrical resistivity were prepared by thermal imidization and selective oxidation between the metal alloy layer and polyamic acid (PAA) layer. Electromagnetic properties of the hybrid thin films in the radio-frequency range were characterized by using the microstrip line method and were correlated with their material parameters. Although anisotropy field of the CoFe/NiFe hybrid film was two times lower than that of the NiFe hybrid film, the saturation magnetization of the CoFe/NiFe hybrid film was three times higher than that of the NiFe hybrid film. The CoFe/NiFe hybrid film showed higher power loss in the frequency range of 3-6 GHz compared to the NiFe hybrid film. The high power loss of the CoFe/NiFe hybrid film was caused by high relative permeability and high ferromagnetic resonance (FMR) frequency due to high saturation magnetization.

  19. High-frequency electromagnetic properties of soft magnetic metal-polyimide hybrid thin films

    International Nuclear Information System (INIS)

    Kim, Sang Woo; Yoon, Chong S.

    2007-01-01

    Although there are a lot of demands for suppression of unwanted high-frequency electromagnetic noise in highly integrated electronic devices such as mobile phones and notebook computers, electromagnetic thin films that effectively work in the high-frequency range have still been underdeveloped. Soft magnetic metal-polyimide (PI) hybrid films with high electrical resistivity were prepared by thermal imidization and selective oxidation between the metal alloy layer and polyamic acid (PAA) layer. Electromagnetic properties of the hybrid thin films in the radio-frequency range were characterized by using the microstrip line method and were correlated with their material parameters. Although anisotropy field of the CoFe/NiFe hybrid film was two times lower than that of the NiFe hybrid film, the saturation magnetization of the CoFe/NiFe hybrid film was three times higher than that of the NiFe hybrid film. The CoFe/NiFe hybrid film showed higher power loss in the frequency range of 3-6 GHz compared to the NiFe hybrid film. The high power loss of the CoFe/NiFe hybrid film was caused by high relative permeability and high ferromagnetic resonance (FMR) frequency due to high saturation magnetization

  20. Characterization of a high performance ultra-thin heat pipe cooling module for mobile hand held electronic devices

    Science.gov (United States)

    Ahamed, Mohammad Shahed; Saito, Yuji; Mashiko, Koichi; Mochizuki, Masataka

    2017-11-01

    In recent years, heat pipes have been widely used in various hand held mobile electronic devices such as smart phones, tablet PCs, digital cameras. With the development of technology these devices have different user friendly features and applications; which require very high clock speeds of the processor. In general, a high clock speed generates a lot of heat, which needs to be spreaded or removed to eliminate the hot spot on the processor surface. However, it is a challenging task to achieve proper cooling of such electronic devices mentioned above because of their confined spaces and concentrated heat sources. Regarding this challenge, we introduced an ultra-thin heat pipe; this heat pipe consists of a special fiber wick structure named as "Center Fiber Wick" which can provide sufficient vapor space on the both sides of the wick structure. We also developed a cooling module that uses this kind of ultra-thin heat pipe to eliminate the hot spot issue. This cooling module consists of an ultra-thin heat pipe and a metal plate. By changing the width, the flattened thickness and the effective length of the ultra-thin heat pipe, several experiments have been conducted to characterize the thermal properties of the developed cooling module. In addition, other experiments were also conducted to determine the effects of changes in the number of heat pipes in a single module. Characterization and comparison of the module have also been conducted both experimentally and theoretically.

  1. DNA hybridization sensor based on pentacene thin film transistor.

    Science.gov (United States)

    Kim, Jung-Min; Jha, Sandeep Kumar; Chand, Rohit; Lee, Dong-Hoon; Kim, Yong-Sang

    2011-01-15

    A DNA hybridization sensor using pentacene thin film transistors (TFTs) is an excellent candidate for disposable sensor applications due to their low-cost fabrication process and fast detection. We fabricated pentacene TFTs on glass substrate for the sensing of DNA hybridization. The ss-DNA (polyA/polyT) or ds-DNA (polyA/polyT hybrid) were immobilized directly on the surface of the pentacene, producing a dramatic change in the electrical properties of the devices. The electrical characteristics of devices were studied as a function of DNA immobilization, single-stranded vs. double-stranded DNA, DNA length and concentration. The TFT device was further tested for detection of λ-phage genomic DNA using probe hybridization. Based on these results, we propose that a "label-free" detection technique for DNA hybridization is possible through direct measurement of electrical properties of DNA-immobilized pentacene TFTs. Copyright © 2010 Elsevier B.V. All rights reserved.

  2. Intrinsic radiation tolerance of ultra-thin GaAs solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Hirst, L. C.; Yakes, M. K.; Warner, J. H.; Schmieder, K. J.; Walters, R. J.; Jenkins, P. P. [U.S. Naval Research Laboratory, 4555 Overlook Ave. SW., Washington, D.C. 20375 (United States); Bennett, M. F. [Sotera Defense Solutions, Inc., Annapolis Junction, Maryland 20701-1067 (United States)

    2016-07-18

    Radiation tolerance is a critical performance criterion of photovoltaic devices for space power applications. In this paper we demonstrate the intrinsic radiation tolerance of an ultra-thin solar cell geometry. Device characteristics of GaAs solar cells with absorber layer thicknesses 80 nm and 800 nm were compared before and after 3 MeV proton irradiation. Both cells showed a similar degradation in V{sub oc} with increasing fluence; however, the 80 nm cell showed no degradation in I{sub sc} for fluences up to 10{sup 14 }p{sup +} cm{sup −2}. For the same exposure, the I{sub sc} of the 800 nm cell had severely degraded leaving a remaining factor of 0.26.

  3. Effect of ambient on electrical transport properties of ultra-thin Au nanowires

    Science.gov (United States)

    Amin, Kazi Rafsanjani; Kundu, Subhajit; Biswas, Sangram; Roy, Ahin; Singh, Abhishek Kumar; Ravishankar, N.; Bid, Aveek

    2016-12-01

    In this letter we present systematic studies of the dynamics of surface adsorption of various chemicals on ultra-thin single crystalline gold nanowires (AuNW) through sensitive resistance fluctuation spectroscopy measurements coupled with ab initio simulations. We show that, contrary to expectations, the adsorption of common chemicals like methanol and acetone has a profound impact on the electrical transport properties of the AuNW. Our measurements and subsequent calculations establish conclusively that in AuNW, semiconductor-like sensitivity to the ambient arises because of changes induced in its local density of states by the surface adsorbed molecules. The extreme sensitivity of the resistance fluctuations of the AuNW to ambient suggests their possible use as solid-state sensors.

  4. Ultra-thin, conformal, and hydratable color-absorbers using silk protein hydrogel

    Science.gov (United States)

    Umar, Muhammad; Min, Kyungtaek; Jo, Minsik; Kim, Sunghwan

    2018-06-01

    Planar and multilayered photonic devices offer unprecedented opportunities in biological and chemical sensing due to strong light-matter interactions. However, uses of rigid substances such as semiconductors and dielectrics confront photonic devices with issues of biocompatibility and a mechanical mismatch for their application on humid, uneven, and soft biological surfaces. Here, we report that favorable material traits of natural silk protein led to the fabrication of an ultra-thin, conformal, and water-permeable (hydratable) metal-insulator-metal (MIM) color absorber that was mapped on soft, curved, and hydrated biological interfaces. Strong absorption was induced in the MIM structure and could be tuned by hydration and tilting of the sample. The transferred MIM color absorbers reached the exhibition of a very strong resonant absorption in the visible and near infra-red ranges. In addition, we demonstrated that the conformal resonator could function as a refractometric glucose sensor applied on a contact lens.

  5. Static and low frequency noise characterization of ultra-thin body InAs MOSFETs

    Science.gov (United States)

    Karatsori, T. A.; Pastorek, M.; Theodorou, C. G.; Fadjie, A.; Wichmann, N.; Desplanque, L.; Wallart, X.; Bollaert, S.; Dimitriadis, C. A.; Ghibaudo, G.

    2018-05-01

    A complete static and low frequency noise characterization of ultra-thin body InAs MOSFETs is presented. Characterization techniques, such as the well-known Y-function method established for Si MOSFETs, are applied in order to extract the electrical parameters and study the behavior of these research grade devices. Additionally, the Lambert-W function parameter extraction methodology valid from weak to strong inversion is also used in order to verify its applicability in these experimental level devices. Moreover, a low-frequency noise characterization of the UTB InAs MOSFETs is presented, revealing carrier trapping/detrapping in slow oxide traps and remote Coulomb scattering as origin of 1/f noise, which allowed for the extraction of the oxide trap areal density. Finally, Lorentzian-like noise is also observed in the sub-micron area devices and attributed to both Random Telegraph Noise from oxide individual traps and g-r noise from the semiconductor interface.

  6. Degradation of Ultra-Thin Gate Oxide NMOSFETs under CVDT and SHE Stresses

    International Nuclear Information System (INIS)

    Shi-Gang, Hu; Yan-Rong, Cao; Yue, Hao; Xiao-Hua, Ma; Chi, Chen; Xiao-Feng, Wu; Qing-Jun, Zhou

    2008-01-01

    Degradation of device under substrate hot-electron (SHE) and constant voltage direct-tunnelling (CVDT) stresses are studied using NMOSFET with 1.4-nm gate oxides. The degradation of device parameters and the degradation of the stress induced leakage current (SILC) under these two stresses are reported. The emphasis of this paper is on SILC and breakdown of ultra-thin-gate-oxide under these two stresses. SILC increases with stress time and several soft breakdown events occur during direct-tunnelling (DT) stress. During SHE stress, SILC firstly decreases with stress time and suddenly jumps to a high level, and no soft breakdown event is observed. For DT injection, the positive hole trapped in the oxide and hole direct-tunnelling play important roles in the breakdown. For SHE injection, it is because injected hot electrons accelerate the formation of defects and these defects formed by hot electrons induce breakdown. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  7. Test beam analysis of ultra-thin hybrid pixel detector assemblies with Timepix readout ASICs

    CERN Document Server

    Alipour Tehrani, Niloufar; Dannheim, Dominik; Firu, Elena; Kulis, Szymon; Redford, Sophie; Sicking, Eva

    2016-01-01

    The requirements for the vertex detector at the proposed Compact Linear Collider imply a very small material budget: less than 0.2% of a radiation length per detection layer including services and mechanical supports. We present here a study using Timepix readout ASICs hybridised to pixel sensors of 50 − 500 μm thickness, including assemblies with 100 μm thick sensors bonded to thinned 100μm thick ASICs. Sensors from three producers (Advacam, Micron Semiconductor Ltd, Canberra) with different edge termination technologies (active edge, slim edge) were bonded to Timepix ASICs. These devices were characterised with the EUDET telescope at the DESY II test beam using 5.6 GeV electrons. Their performance for the detection and tracking of minimum ionising particles was evaluated in terms of charge sharing, detection efficiency, single-point resolution and energy deposition.

  8. Advanced engineering materials and thick film hybrid circuit technology

    International Nuclear Information System (INIS)

    Faisal, S.; Aslam, M.; Mehmood, K.

    2006-01-01

    The use of Thick Film hybrid Technology to manufacture electronic circuits and passive components continues to grow at rapid rate. Thick Film Technology can be viewed as a means of packaging active devices, spanning the gap between monolithic integrated circuit chips and printed circuit boards with attached active and passive components. An advancement in engineering materials has moved from a formulating art to a base of greater understanding of relationship of material chemistry to the details of electrical and mechanical performance. This amazing advancement in the field of engineering materials has brought us up to a magnificent standard that we are able to manufacture small size, low cost and sophisticated electronic circuits of Military, Satellite systems, Robotics, Medical and Telecommunications. (author)

  9. In-situ fabrication of hybrid polyoxometalate nanoparticles composite films

    International Nuclear Information System (INIS)

    Lan Yang; Mao Baodong; Wang Enbo; Song Yonghai; Kang Zhenhui; Wang Chunlei; Tian Chungui; Zhang Chao; Xu Lin; Li Zhuang

    2007-01-01

    Inorganic-organic hybrid nanoparticles multilayer films were fabricated by extending the method of nucleation and growth of particles in polymer assemblies. The polyelectrolyte matrix was constructed by layer-by-layer self-assembly method. Synthesis of polyoxometalate nanoparticles was achieved by alternately dipping the precursor polyelectrolyte matrix into AgNO 3 and H 4 SiW 12 O 40 aqueous solutions. Repeating the above synthesis process, Ag 4 SiW 12 O 40 nanoparticles with controllable diameters of 20 to 77 nm were synthesized in the multilayer films in-situ. UV-vis absorption spectra indicate that the nanoparticles grew gradually in the synthesis process. Transmission electron microscopy was used to observe the size and morphology of the nanoparticles

  10. Silicon nanowires in polymer nanocomposites for photovoltaic hybrid thin films

    International Nuclear Information System (INIS)

    Ben Dkhil, S.; Bourguiga, R.; Davenas, J.; Cornu, D.

    2012-01-01

    Highlights: ► Hybrid solar cells based on blends of poly(N-vinylcarbazole) and silicon nanowires have been fabricated. ► We have investigated the charge transfer between PVK and SiNWs by the way of the quenching of the PVK photoluminescence. ► The relation between the morphology of the composite thin films and the charge transfer between SiNWs and PVK has been examined. ► We have investigated the effects of SiNWs concentration on the photovoltaic characteristics leading to the optimization of a critical SiNWs concentration. - Abstract: Hybrid thin films combining the high optical absorption of a semiconducting polymer film and the electronic properties of silicon fillers have been investigated in the perspective of the development of low cost solar cells. Bulk heterojunction photovoltaic materials based on blends of a semiconductor polymer poly(N-vinylcarbazole) (PVK) as electron donor and silicon nanowires (SiNWs) as electron acceptor have been studied. Composite PVK/SiNWs films were cast from a common solvent mixture. UV–visible spectrometry and photoluminescence of the composites have been studied as a function of the SiNWs concentration. Photoluminescence spectroscopy (PL) shows the existence of a critical SiNWs concentration of about 10 wt % for PL quenching corresponding to the most efficient charge pair separation. The photovoltaic (PV) effect has been studied under illumination. The optimum open-circuit voltage V oc and short-circuit current density J sc are obtained for 10 wt % SiNWs whereas a degradation of these parameters is observed at higher SiNWs concentrations. These results are correlated to the formation of aggregates in the composite leading to recombination of the photogenerated charge pairs competing with the dissociation mechanism.

  11. Extrinsic versus intrinsic ferroelectric switching: experimental investigations using ultra-thin PVDF Langmuir-Blodgett films

    International Nuclear Information System (INIS)

    Kliem, H; Tadros-Morgane, R

    2005-01-01

    Mechanisms of extrinsic and intrinsic switching phenomena in ferroelectrics are explained and existing models are summarized. Then, criteria for an experimental distinction between both models are elaborated. Samples with thicknesses ranging from 2.7 to 63.8 nm prepared by a Langmuir-Blodgett technique were investigated with respect to these criteria. Measurements of their polarization switching behaviour, their polarization hysteresis loops, and their coercive fields were carried out. It is found that the coercive fields increase with decreasing sample thickness. Also, the switching time increases with decreasing sample thickness and it increases with decreasing field strength. The switching process turns out to be thermally activated. We find that neither intrinsic nor extrinsic models are sufficient to describe the experimental situation

  12. First-Principles Study of Superconductivity in Ultra- thin Pb Films

    Science.gov (United States)

    Noffsinger, Jesse; Cohen, Marvin L.

    2010-03-01

    Recently, superconductivity in ultrathin layered Pb has been confirmed in samples with as few as two atomic layers [S. Qin, J. Kim, Q. Niu, and C.-K. Shih, Science 2009]. Interestingly, the prototypical strong-coupling superconductor exhibits different Tc's for differing surface reconstructions in samples with only two monolayers. Additionally, Tc is seen to oscillate as the number of atomic layers is increased. Using first principles techniques based on Wannier functions, we analyze the electronic structure, lattice dynamics and electron-phonon coupling for varying thicknesses and surface reconstructions of layered Pb. We discuss results as they relate to superconductivity in the bulk, for which accurate calculations of superconducting properties can be compared to experiment [W. L. McMillan and J.M. Rowell, PRL 1965]. This work was supported by National Science Foundation Grant No. DMR07-05941, the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Computational resources have been provided by the Lawrencium computational cluster resource provided by the IT Division at the Lawrence Berkeley National Laboratory (Supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231)

  13. Nanostructure Control: Nucleation and Diffusion Studies for Predictable Ultra Thin Film Morphologies

    Science.gov (United States)

    Hershberger, Matthew Thomas

    This thesis covers PhD research on two systems with unique and interesting physics. The first system is lead (Pb) deposited on the silicon (111) surface with the 7x7 reconstruction. Pb and Si are mutually bulk insolubility resulting in this system being an ideal case for studying metal and semiconductor interactions. Initial Pb deposition causes an amorphous wetting layer to form across to surface. Continued deposition results in Pb(111) island growth. Classic literature has classified this system as the Stranski-Krastanov growth mode although the system is not near equilibrium conditions. Our research shows a growth mode distinctly different than classical expectations and begins a discussion of reclassifying diffusion and nucleation for systems far away from the well-studied equilibrium cases. The second system studied investigates the interactions of the Rare Earth metal Dysprosium (Dy) with a carbon based 2D lattice called graphene. Graphene is a 2D material composed of carbon atoms arranged in hexagons, similar to a honeycomb with carbon atoms at each corner. The graphene we used is grown epitaxially from a substrate of silicon carbide. This creates a multilayered playground to study how metals interact both on the surface of graphene and intercalated in between graphene layers. Many types of atoms have been studied in graphene systems, but the rare earths and in particular Dy have not been well investigated. This thesis contributes to the knowledge base of graphene on SiC structure and metal-graphene interactions. These systems have been investigated in ultra-high vacuum (UHV) environments with base pressures around 5.0x10-11 torr. The Pb/Si(111)-7x7 system was investigated with scanning tunneling microscopy (STM) and the Graphene/SiC system was investigated with both STM and Spot Profile Analyzing Low Energy Electron Diffraction (SPA-LEED).

  14. Nanostructure control: Nucleation and diffusion studies for predictable ultra thin film morphologies

    Energy Technology Data Exchange (ETDEWEB)

    Hershberger, Matthew [Iowa State Univ., Ames, IA (United States)

    2017-05-06

    This thesis covers PhD research on two systems with unique and interesting physics. The first system is lead (Pb) deposited on the silicon (111) surface with the 7x7 reconstruction. Pb and Si are mutually bulk insoluble resulting in this system being an ideal case for studying metal and semiconductor interactions. Initial Pb deposition causes an amorphous wetting layer to form across to surface. Continued deposition results in Pb(111) island growth. Classic literature has classified this system as the Stranski-Krastanov growth mode although the system is not near equilibrium conditions. Our research shows a growth mode distinctly different than classical expectations and begins a discussion of reclassifying diffusion and nucleation for systems far away from the well-studied equilibrium cases.

  15. Continuous Ultra-Thin MOS2 Films Grown by Low-Temperature Physical Vapor Deposition (Postprint)

    Science.gov (United States)

    2014-07-01

    MoS2 target of 99.95% purity. The SiO2 and highly oriented pyrolitic graphite (HOPG) substrates were intro- duced via a vacuum load- lock and mounted on...im- mediately prior insertion into a sample vacuum load- lock . In this work, the samples were heated to 350 C and allowed to rotate at approximately...136805 (2010). 6H. Terrones, F. Lopez-Urias, and M. Terrones, Sci. Rep. 3(203), 1549 (2013). 7H. Li, Q. Zhang, C. C. R. Yap, B. K. Tay, T. H. T. Edwin

  16. Anatase TiO2 hierarchical structures composed of ultra-thin nano-sheets exposing high percentage {0 0 1} facets and their application in quantum-dot sensitized solar cells

    International Nuclear Information System (INIS)

    Wu, Dapeng; Zhang, Shuo; Jiang, Shiwei; He, Jinjin; Jiang, Kai

    2015-01-01

    Graphical abstract: TiO 2 hierarchical structures assembled from ultra-thin nanosheets exposing ∼90% {0 0 1} facets were employed as photoanode materials to improve the performance of CdS/CdSe co-sensitized solar cells. - Highlights: • THSs composited of nanosheets exposing high percent {0 0 1} facets were prepared. • THSs improve the QDs loading amount and light scattering of the photoanode. • THSs suppress the carrier recombination and finally lead to ∼25% PCE improvement. - Abstract: TiO 2 hierarchical structures (THSs) composed of ultra-thin nano-sheets exposing ∼90% {0 0 1} facets were prepared via a hydrothermal method. Time dependent trails revealed the formation of THSs experienced a self-assemble process. The as-prepared product were used as the photoanode materials for CdS/CdSe co-sensitized solar cells, and the THSs/nanoparticle hybrid photoanode demonstrated a power conversion efficiency of 3.47%, indicating ∼25% improvement compared with the nanoparticle cell

  17. Anatase TiO{sub 2} hierarchical structures composed of ultra-thin nano-sheets exposing high percentage {0 0 1} facets and their application in quantum-dot sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Dapeng, E-mail: dpengwu@126.com [School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007 (China); Collaborative Innovation Center of Henan Province for Green Motive Power and Key Materials, Henan Key Laboratory of Photovoltaic Materials, Henan Normal University, Xinxiang, Henan 453007 (China); Zhang, Shuo; Jiang, Shiwei; He, Jinjin [School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007 (China); Jiang, Kai [School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007 (China); Collaborative Innovation Center of Henan Province for Green Motive Power and Key Materials, Henan Key Laboratory of Photovoltaic Materials, Henan Normal University, Xinxiang, Henan 453007 (China)

    2015-03-05

    Graphical abstract: TiO{sub 2} hierarchical structures assembled from ultra-thin nanosheets exposing ∼90% {0 0 1} facets were employed as photoanode materials to improve the performance of CdS/CdSe co-sensitized solar cells. - Highlights: • THSs composited of nanosheets exposing high percent {0 0 1} facets were prepared. • THSs improve the QDs loading amount and light scattering of the photoanode. • THSs suppress the carrier recombination and finally lead to ∼25% PCE improvement. - Abstract: TiO{sub 2} hierarchical structures (THSs) composed of ultra-thin nano-sheets exposing ∼90% {0 0 1} facets were prepared via a hydrothermal method. Time dependent trails revealed the formation of THSs experienced a self-assemble process. The as-prepared product were used as the photoanode materials for CdS/CdSe co-sensitized solar cells, and the THSs/nanoparticle hybrid photoanode demonstrated a power conversion efficiency of 3.47%, indicating ∼25% improvement compared with the nanoparticle cell.

  18. Tunnelling conductive hybrid films of gold nanoparticles and cellulose and their applications as electrochemical electrodes

    International Nuclear Information System (INIS)

    Liu, Zhiming; Wang, Xuefeng; Wu, Wenjian; Li, Mei

    2015-01-01

    Conductive hybrid films of metal nanoparticles and polymers have practical applications in the fields of sensing, microelectronics and catalysis, etc. Herein, we present the electrochemical availability of tunnelling conductive hybrid films of gold nanoparticles (GNPs) and cellulose. The hybrid films were provided with stable tunnelling conductive properties with 12 nm GNPs of 12.7% (in weight). For the first time, the conductive hybrid films were used as substrates of electrochemical electrodes to load calmodulin (CaM) proteins for sensing of calcium cations. The electrodes of hybrid films with 20 nm GNPs of 46.7% (in weight) exhibited stable electrochemical properties, and showed significant responses to calcium cations with concentrations as low as 10 −9 M after being loaded with CaM proteins. (paper)

  19. 2D Organic-Inorganic Hybrid Thin Films for Flexible UV-Visible Photodetectors

    KAUST Repository

    Velusamy, Dhinesh Babu

    2017-02-13

    Flexible 2D inorganic MoS and organic g-CN hybrid thin film photodetectors with tunable composition and photodetection properties are developed using simple solution processing. The hybrid films fabricated on paper substrate show broadband photodetection suitable for both UV and visible light with good responsivity, detectivity, and reliable and rapid photoswitching characteristics comparable to monolayer devices. This excellent performance is retained even after the films are severely deformed at a bending radius of ≈2 mm for hundreds of cycles. The detailed charge transfer and separation processes at the interface between the 2D materials in the hybrid films are confirmed by femtosecond transient absorption spectroscopy with broadband capability.

  20. Ultra-thin flexible GaAs photovoltaics in vertical forms printed on metal surfaces without interlayer adhesives

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Juho; Song, Kwangsun; Kim, Namyun; Lee, Jongho, E-mail: jong@gist.ac.kr [School of Mechanical Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005 (Korea, Republic of); Research Institute for Solar and Sustainable Energies (RISE), Gwangju Institute of Science and Technology (GIST), Gwangju 61005 (Korea, Republic of); Hwang, Jeongwoo [Photonic Bio Research Center, Korea Photonics Technology Institute (KOPTI), 9 Cheomdanventure-ro 108beon-gil, Gwangju 61007 (Korea, Republic of); Shin, Jae Cheol [Department of Physics, Yeungnam University, Gyeongsan, Gyeongbuk 38541 (Korea, Republic of)

    2016-06-20

    Wearable flexible electronics often require sustainable power sources that are also mechanically flexible to survive the extreme bending that accompanies their general use. In general, thinner microelectronic devices are under less strain when bent. This paper describes strategies to realize ultra-thin GaAs photovoltaics through the interlayer adhesiveless transfer-printing of vertical-type devices onto metal surfaces. The vertical-type GaAs photovoltaic devices recycle reflected photons by means of bottom electrodes. Systematic studies with four different types of solar microcells indicate that the vertical-type solar microcells, at only a quarter of the thickness of similarly designed lateral-type cells, generate a level of electric power similar to that of thicker cells. The experimental results along with the theoretical analysis conducted here show that the ultra-thin vertical-type solar microcells are durable under extreme bending and thus suitable for use in the manufacturing of wearable flexible electronics.

  1. Synthesis and characterization of polyimide-epoxy hybrid films

    International Nuclear Information System (INIS)

    Butt, M.S.; Akhter, Z.; Siddiqi, H.M.

    2011-01-01

    Composites from polyimide and epoxy-amine were prepared aiming for enhancing its thermal and mechanical properties. Polyimide-epoxy-amine hybrid films were prepared by blending of polyimide and epoxy-amine in different ratios whereas, polyimide was prepared by reacting 1,2-di(p-aminophenyloxy)ethylene with 3,3/sub '/4,4/sub '/-benzophenone tetracarboxylic acid dianhydride. The blend systems with Araldite LY564 (1,4-butanediolediglycidyl ether) (BDDE) and Hardener HY2954 (3,3/sub '/-dimethyl-4,4/sub '/-diamino dicyclohexyl)methane (MACM) were investigated in term of thermal, mechanical and viscoelastic measurements. Thermal stability was determined using thermogravimetric analysis. The effect of the polyimide content on the glass transition temperature (Tg) and thermal stability was observed. Viscoelastic measurements showed that the glass transition temperature shifted with the increase of polyimide content. The composites showed higher thermal stability in comparison with neat epoxy-amine matrix for higher polyimide concentration. The effect of polyimide content on the mechanical properties was also investigated. The tensile measurements of the films showed that with the increase of polyimide content the tensile modulus of the films was increased. (author)

  2. The production of ultra-thin layers of ion-exchange resin and metallic silver by electrospraying

    International Nuclear Information System (INIS)

    Wyllie, H.A.

    1988-10-01

    Highly efficient radioactive sources for use in radioisotope metrology have been prepared on ultra-thin layers of electrosprayed ion-exchange resin. The efficiency of these sources can be reduced for the purpose of radioactivity standardisation by coating them with conducting silver layers which are also produced by electrospraying. A description is given of improvements to the electrospraying methods, together with details of the rotating, oscillating source-mount turntable

  3. Creation of a longitudinally polarized subwavelength hotspot with an ultra-thin planar lens: vectorial Rayleigh–Sommerfeld method

    International Nuclear Information System (INIS)

    Ye, Huapeng; Qiu, Cheng-Wei; Huang, Kun; Yeo, Swee Ping; Teng, Jinghua; Luk’yanchuk, Boris

    2013-01-01

    This letter shows how a longitudinally polarized hotspot can be created by a planar ultra-thin lens that beats the diffraction limit. On the imaging plane, a subwavelength optical resolution 0.39λ with almost purely longitudinal electric component has been demonstrated in air ambient. This novel paradigm addresses simultaneously both longitudinal polarization and deep sub-diffraction imaging, by a planar lens composed of ultra-thin opaque concentric annuli. The vectorial Rayleigh–Sommerfeld (VRS) approach, offering the advantage of significant reduction in computation, has been developed for a particular optimization of a flat lens with full control of polarization. Empowered by the robustness of VRS in dealing with polarization states, the proposed roadmap may be universally and efficiently integrated with other optimization algorithms to design super-resolution imaging with controlled polarization states at any wavelength without luminescence of the object. The lens, which is empowered by the proposed method, opens an avenue for the first time toward a highly integrated imaging system with advanced functionalities in far-field super-imaging, tailored polarization states and flat ultra-thin geometry simultaneously. (letter)

  4. Enhanced cooling in mono-crystalline ultra-thin silicon by embedded micro-air channels

    Directory of Open Access Journals (Sweden)

    Mohamed T. Ghoneim

    2015-12-01

    Full Text Available In today’s digital world, complementary metal oxide semiconductor (CMOS technology enabled scaling of bulk mono-crystalline silicon (100 based electronics has resulted in their higher performance but with increased dynamic and off-state power consumption. Such trade-off has caused excessive heat generation which eventually drains the charge of battery in portable devices. The traditional solution utilizing off-chip fans and heat sinks used for heat management make the whole system bulky and less mobile. Here we show, an enhanced cooling phenomenon in ultra-thin (>10 μm mono-crystalline (100 silicon (detached from bulk substrate by utilizing deterministic pattern of porous network of vertical “through silicon” micro-air channels that offer remarkable heat and weight management for ultra-mobile electronics, in a cost effective way with 20× reduction in substrate weight and a 12% lower maximum temperature at sustained loads. We also show the effectiveness of this event in functional MOS field effect transistors (MOSFETs with high-κ/metal gate stacks.

  5. Effects of ultra-thin Si-fin body widths upon SOI PMOS FinFETs

    Science.gov (United States)

    Liaw, Yue-Gie; Chen, Chii-Wen; Liao, Wen-Shiang; Wang, Mu-Chun; Zou, Xuecheng

    2018-05-01

    Nano-node tri-gate FinFET devices have been developed after integrating a 14 Å nitrided gate oxide upon the silicon-on-insulator (SOI) wafers established on an advanced CMOS logic platform. These vertical double gate (FinFET) devices with ultra-thin silicon fin (Si-fin) widths ranging from 27 nm to 17 nm and gate length down to 30 nm have been successfully developed with a 193 nm scanner lithography tool. Combining the cobalt fully silicidation and the CESL strain technology beneficial for PMOS FinFETs was incorporated into this work. Detailed analyses of Id-Vg characteristics, threshold voltage (Vt), and drain-induced barrier lowering (DIBL) illustrate that the thinnest 17 nm Si-fin width FinFET exhibits the best gate controllability due to its better suppression of short channel effect (SCE). However, higher source/drain resistance (RSD), channel mobility degradation due to dry etch steps, or “current crowding effect” will slightly limit its transconductance (Gm) and drive current.

  6. Micro-architecture embedding ultra-thin interlayer to bond diamond and silicon via direct fusion

    Science.gov (United States)

    Kim, Jong Cheol; Kim, Jongsik; Xin, Yan; Lee, Jinhyung; Kim, Young-Gyun; Subhash, Ghatu; Singh, Rajiv K.; Arjunan, Arul C.; Lee, Haigun

    2018-05-01

    The continuous demand on miniaturized electronic circuits bearing high power density illuminates the need to modify the silicon-on-insulator-based chip architecture. This is because of the low thermal conductivity of the few hundred nanometer-thick insulator present between the silicon substrate and active layers. The thick insulator is notorious for releasing the heat generated from the active layers during the operation of devices, leading to degradation in their performance and thus reducing their lifetime. To avoid the heat accumulation, we propose a method to fabricate the silicon-on-diamond (SOD) microstructure featured by an exceptionally thin silicon oxycarbide interlayer (˜3 nm). While exploiting the diamond as an insulator, we employ spark plasma sintering to render the silicon directly fused to the diamond. Notably, this process can manufacture the SOD microarchitecture via a simple/rapid way and incorporates the ultra-thin interlayer for minute thermal resistance. The method invented herein expects to minimize the thermal interfacial resistance of the devices and is thus deemed as a breakthrough appealing to the current chip industry.

  7. Proton probing of ultra-thin foil dynamics in high intensity regime

    Science.gov (United States)

    Prasad, Rajendra; Aktan, Esin; Aurand, Bastian; Cerchez, Mirela; Willi, Oswald

    2017-10-01

    The field of laser driven ion acceleration has been enriched significantly over the past decade, thanks to the advanced laser technologies. Already, from 100s TW class systems, laser driven sources of particles and radiations are being considered in number of potential applications in science and medicine due to their unique properties. New physical effects unearthed at these systems may help understand and conduct successful experiments at several PW class multi-beam facilities with high rep rate systems, e.g. ELI. Here we present the first experimental results on ultra-thin foil dynamics irradiated by an ultra-high intensity (1020 W/cm2) , ultra-high contrast (10-12) laser pulse at ARCTURUS laser facility at HHU Duesseldorf. By employing the elegant proton probing technique it is observed that for the circular polarization of laser light, a 100nm thin target is pushed forward as a compressed layer due to the radiation pressure of light. Whereas, the linear polarization seems to decompress the target drastically. 2D particle-in-cell simulations corroborate the experimental findings. Our results confirm the previous simulation studies investigating the fundamental role played by light polarization, finite focus spot size effect and eventually electron heating including the oblique incidence at the target edges.

  8. Formation of a highly doped ultra-thin amorphous carbon layer by ion bombardment of graphene

    Science.gov (United States)

    Piotr Michałowski, Paweł; Pasternak, Iwona; Ciepielewski, Paweł; Guinea, Francisco; Strupiński, Włodek

    2018-07-01

    Ion bombardment of graphene leads to the formation of defects which may be used to tune properties of the graphene based devices. In this work, however, we present that the presence of the graphene layer on a surface of a sample has a significant impact on the ion bombardment process: broken sp2 bonds react with the incoming ions and trap them close to the surface of the sample, preventing a standard ion implantation. For an ion bombardment with a low impact energy and significant dose (in the range of 1014 atoms cm‑2) an amorphization of the graphene layer is observed but at the same time, most of the incoming ions do not penetrate the sample but stop at the surface, thus forming a highly doped ultra-thin amorphous carbon layer. The effect may be used to create thin layers containing desired atoms if no other technique is available. This approach is particularly useful for secondary ion mass spectrometry where a high concentration of Cs at the surface of a sample significantly enhances the negative ionization probability, allowing it to reach better detection limits.

  9. On-chip ultra-thin layer chromatography and surface enhanced Raman spectroscopy.

    Science.gov (United States)

    Chen, Jing; Abell, Justin; Huang, Yao-wen; Zhao, Yiping

    2012-09-07

    We demonstrate that silver nanorod (AgNR) array substrates can be used for on-chip separation and detection of chemical mixtures by combining ultra-thin layer chromatography (UTLC) and surface enhanced Raman spectroscopy (SERS). The UTLC-SERS plate consists of an AgNR array fabricated by oblique angle deposition. The capability of the AgNR substrates to separate the different compounds in a mixture was explored using a mixture of four dyes and a mixture of melamine and Rhodamine 6G at varied concentrations with different mobile phase solvents. After UTLC separation, spatially-resolved SERS spectra were collected along the mobile phase development direction and the intensities of specific SERS peaks from each component were used to generate chromatograms. The AgNR substrates demonstrate the potential for separating the test dyes with plate heights as low as 9.6 μm. The limits of detection are between 10(-5)-10(-6) M. Furthermore, we show that the coupling of UTLC with SERS improves the SERS detection specificity, as small amounts of target analytes can be separated from the interfering background components.

  10. Facile design of ultra-thin anodic aluminum oxide membranes for the fabrication of plasmonic nanoarrays

    Science.gov (United States)

    Hao, Qi; Huang, Hao; Fan, Xingce; Hou, Xiangyu; Yin, Yin; Li, Wan; Si, Lifang; Nan, Haiyan; Wang, Huaiyu; Mei, Yongfeng; Qiu, Teng; Chu, Paul K.

    2017-03-01

    Ultra-thin anodic aluminum oxide (AAO) membranes are efficient templates for the fabrication of patterned nanostructures. Herein, a three-step etching method to control the morphology of AAO is described. The morphological evolution of the AAO during phosphoric acid etching is systematically investigated and a nonlinear growth mechanism during unsteady-state anodization is revealed. The thickness of the AAO can be quantitatively controlled from ˜100 nm to several micrometers while maintaining the tunablity of the pore diameter. The AAO membranes are robust and readily transferable to different types of substrates to prepare patterned plasmonic nanoarrays such as nanoislands, nanoclusters, ultra-small nanodots, and core-satellite superstructures. The localized surface plasmon resonance from these nanostructures can be easily tuned by adjusting the morphology of the AAO template. The custom AAO template provides a platform for the fabrication of low-cost and large-scale functional nanoarrays suitable for fundamental studies as well as applications including biochemical sensing, imaging, photocatalysis, and photovoltaics.

  11. Enhanced cooling in mono-crystalline ultra-thin silicon by embedded micro-air channels

    KAUST Repository

    Ghoneim, Mohamed T.; Fahad, Hossain M.; Hussain, Aftab M.; Rojas, Jhonathan Prieto; Sevilla, Galo T.; Alfaraj, Nasir; Lizardo, Ernesto B.; Hussain, Muhammad Mustafa

    2015-01-01

    In today’s digital world, complementary metal oxide semiconductor (CMOS) technology enabled scaling of bulk mono-crystalline silicon (100) based electronics has resulted in their higher performance but with increased dynamic and off-state power consumption. Such trade-off has caused excessive heat generation which eventually drains the charge of battery in portable devices. The traditional solution utilizing off-chip fans and heat sinks used for heat management make the whole system bulky and less mobile. Here we show, an enhanced cooling phenomenon in ultra-thin (>10 μm) mono-crystalline (100) silicon (detached from bulk substrate) by utilizing deterministic pattern of porous network of vertical “through silicon” micro-air channels that offer remarkable heat and weight management for ultra-mobile electronics, in a cost effective way with 20× reduction in substrate weight and a 12% lower maximum temperature at sustained loads. We also show the effectiveness of this event in functional MOS field effect transistors (MOSFETs) with high-κ/metal gate stacks.

  12. Analysis of switching characteristics for negative capacitance ultra-thin-body germanium-on-insulator MOSFETs

    Science.gov (United States)

    Pi-Ho Hu, Vita; Chiu, Pin-Chieh

    2018-04-01

    The impact of device parameters on the switching characteristics of negative capacitance ultra-thin-body (UTB) germanium-on-insulator (NC-GeOI) MOSFETs is analyzed. NC-GeOI MOSFETs with smaller gate length (L g), EOT, and buried oxide thickness (T box) and thicker ferroelectric layer thickness (T FE) exhibit larger subthreshold swing improvements over GeOI MOSFETs due to better capacitance matching. Compared with GeOI MOSFETs, NC-GeOI MOSFETs exhibit better switching time due to improvements in effective drive current (I eff) and subthreshold swing. NC-GeOI MOSFET exhibits larger ST improvements at V dd = 0.3 V (-82.9%) than at V dd = 0.86 V (-9.7%), because NC-GeOI MOSFET shows 18.2 times higher I eff than the GeOI MOSFET at V dd = 0.3 V, while 2.5 times higher I eff at V dd = 0.86 V. This work provides the device design guideline of NC-GeOI MOSFETs for ultra-low power applications.

  13. Enhanced cooling in mono-crystalline ultra-thin silicon by embedded micro-air channels

    KAUST Repository

    Ghoneim, Mohamed T.

    2015-12-11

    In today’s digital world, complementary metal oxide semiconductor (CMOS) technology enabled scaling of bulk mono-crystalline silicon (100) based electronics has resulted in their higher performance but with increased dynamic and off-state power consumption. Such trade-off has caused excessive heat generation which eventually drains the charge of battery in portable devices. The traditional solution utilizing off-chip fans and heat sinks used for heat management make the whole system bulky and less mobile. Here we show, an enhanced cooling phenomenon in ultra-thin (>10 μm) mono-crystalline (100) silicon (detached from bulk substrate) by utilizing deterministic pattern of porous network of vertical “through silicon” micro-air channels that offer remarkable heat and weight management for ultra-mobile electronics, in a cost effective way with 20× reduction in substrate weight and a 12% lower maximum temperature at sustained loads. We also show the effectiveness of this event in functional MOS field effect transistors (MOSFETs) with high-κ/metal gate stacks.

  14. Design of a superhydrophobic and superoleophilic film using cured fluoropolymer@silica hybrid

    International Nuclear Information System (INIS)

    Yang, Hao; Pi, Pihui; Yang, Zhuo-ru; Lu, Zhong; Chen, Rong

    2016-01-01

    Graphical abstract: - Highlights: • Cured fluoropolymer@silica hybrid was coated on stainless steel mesh. • The hybrid film showed superhydrophobicity and superoleophilicity by adjusting silica dosage. • The hybrid film exhibited good thermal stability and excellent oil/water separation efficiency. - Abstract: Recently, considerable efforts have been made on superhydrophobic–superoleophilic filter to satisfy the requirements of the applications to oil/water separation. In this work, we obtained a superhydrophobic and superoleophilic film by coating cured fluoropolymer@silica hybrid on stainless steel mesh. Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and thermogravimetric-differential scanning calorimetry (TG-DSC) were used to determine the chemical composition and thermal stability of the sample. The effect of silica nanoparticles (NPs) concentration on the surface property of the hybrid film was analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle analyzer. The results indicate that silica NPs not only enhance the thermal stability, but also strengthen the hydrophobicity and oleophilicity of the film. When 20 wt% silica NPs was added into the thermosetting fluoropolymer, the hybrid film shows both superhydrophobicity and superoleophilicity owing to the large surface roughness factor (RMS) and porous structure. Moreover, the hybrid film could be used to separate water from different oils effectively. When the pore size of the mesh is less than 300 μm, the oil/water separation efficiency of the film reaches above 99%, which shows a great potential application to dehydrate fuel oils.

  15. Design of a superhydrophobic and superoleophilic film using cured fluoropolymer@silica hybrid

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Hao [Key Laboratory for Green Chemical Process of Ministry of Education and School of Chemistry and Environmental Engineering, Wuhan Institute of Technology, Xiongchu Street, Wuhan, 430073 (China); Pi, Pihui; Yang, Zhuo-ru [School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 510640 (China); Lu, Zhong [Key Laboratory for Green Chemical Process of Ministry of Education and School of Chemistry and Environmental Engineering, Wuhan Institute of Technology, Xiongchu Street, Wuhan, 430073 (China); Chen, Rong, E-mail: rchenhku@hotmail.com [Key Laboratory for Green Chemical Process of Ministry of Education and School of Chemistry and Environmental Engineering, Wuhan Institute of Technology, Xiongchu Street, Wuhan, 430073 (China)

    2016-12-01

    Graphical abstract: - Highlights: • Cured fluoropolymer@silica hybrid was coated on stainless steel mesh. • The hybrid film showed superhydrophobicity and superoleophilicity by adjusting silica dosage. • The hybrid film exhibited good thermal stability and excellent oil/water separation efficiency. - Abstract: Recently, considerable efforts have been made on superhydrophobic–superoleophilic filter to satisfy the requirements of the applications to oil/water separation. In this work, we obtained a superhydrophobic and superoleophilic film by coating cured fluoropolymer@silica hybrid on stainless steel mesh. Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and thermogravimetric-differential scanning calorimetry (TG-DSC) were used to determine the chemical composition and thermal stability of the sample. The effect of silica nanoparticles (NPs) concentration on the surface property of the hybrid film was analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle analyzer. The results indicate that silica NPs not only enhance the thermal stability, but also strengthen the hydrophobicity and oleophilicity of the film. When 20 wt% silica NPs was added into the thermosetting fluoropolymer, the hybrid film shows both superhydrophobicity and superoleophilicity owing to the large surface roughness factor (RMS) and porous structure. Moreover, the hybrid film could be used to separate water from different oils effectively. When the pore size of the mesh is less than 300 μm, the oil/water separation efficiency of the film reaches above 99%, which shows a great potential application to dehydrate fuel oils.

  16. Micropatterned superconducting film circuitry for operation in hybrid quantum devices

    International Nuclear Information System (INIS)

    Bothner, Daniel

    2013-01-01

    This thesis discusses three aspects of the arduous way towards hybrid quantum systems consisting of superconducting circuits and ensembles of ultracold paramagnetic atoms. In the first part of the thesis, superconducting coplanar microwave resonators as used for quantum information processing with superconducting qubits are investigated in magnetic fields. In the second part of the thesis integrated atom chips are designed and fabricated, which offer the possibility to trap an ensemble of ultracold atoms close to a superconducting coplanar resonator on that chip. In the third and last part of the thesis, unconventional disordered and quasiperiodic arrangements of microfabricated holes (antidots) in superconducting films are patterned and investigated with respect to the impact of the arrangement on the superconductor transport properties in magnetic fields.

  17. Impact of built-in fields and contact configuration on the characteristics of ultra-thin GaAs solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Aeberhard, Urs, E-mail: u.aeberhard@fz-juelich.de [IEK-5 Photovoltaik, Forschungszentrum Jülich, D-52425 Jülich (Germany)

    2016-07-18

    We discuss the effects of built-in fields and contact configuration on the photovoltaic characteristics of ultra-thin GaAs solar cells. The investigation is based on advanced quantum-kinetic simulations reaching beyond the standard semi-classical bulk picture concerning the consideration of charge carrier states and dynamics in complex potential profiles. The thickness dependence of dark and photocurrent in the ultra-scaled regime is related to the corresponding variation of both, the built-in electric fields and associated modification of the density of states, and the optical intensity in the films. Losses in open-circuit voltage and short-circuit current due to the leakage of electronically and optically injected carriers at minority carrier contacts are investigated for different contact configurations including electron and hole blocking barrier layers. The microscopic picture of leakage currents is connected to the effect of finite surface recombination velocities in the semi-classical description, and the impact of these non-classical contact regions on carrier generation and extraction is analyzed.

  18. Impact of ultra-thin Al2O3-y layers on TiO2-x ReRAM switching characteristics

    Science.gov (United States)

    Trapatseli, Maria; Cortese, Simone; Serb, Alexander; Khiat, Ali; Prodromakis, Themistoklis

    2017-05-01

    Transition metal-oxide resistive random access memory devices have demonstrated excellent performance in switching speed, versatility of switching and low-power operation. However, this technology still faces challenges like poor cycling endurance, degradation due to high electroforming (EF) switching voltages and low yields. Approaches such as engineering of the active layer by doping or addition of thin oxide buffer layers have been often adopted to tackle these problems. Here, we have followed a strategy that combines the two; we have used ultra-thin Al2O3-y buffer layers incorporated between TiO2-x thin films taking into account both 3+/4+ oxidation states of Al/Ti cations. Our devices were tested by DC and pulsed voltage sweeping and in both cases demonstrated improved switching voltages. We believe that the Al2O3-y layers act as reservoirs of oxygen vacancies which are injected during EF, facilitate a filamentary switching mechanism and provide enhanced filament stability, as shown by the cycling endurance measurements.

  19. Enhanced thermoelectric properties of bismuth telluride-organic hybrid films via graphene doping

    International Nuclear Information System (INIS)

    Rahman, Airul Azha Abd; Umar, Akrajas Ali; Salleh, Muhamad Mat; Chen, Xiaomei; Oyama, Munetaka

    2016-01-01

    The thermoelectric properties of graphene-doped bismuth telluride-PEDOT:PSS-glycerol (hybrid) films were investigated. Prior to the study, p-type and n-type hybrid films were prepared by doping the PEDOT:PSS-glycerol with the p- and n-type bismuth telluride. Graphene-doped hybrid films were prepared by adding graphene particles of concentration ranging from 0.02 to 0.1 wt% into the hybrid films. Films of graphene-doped hybrid system were then prepared on a glass substrate using a spin-coating technique. It was found that the electrical conductivity of the hybrid films increases with the increasing of the graphene-dopant concentration and optimum at 0.08 wt% for both p- and n-type films, namely 400 and 195 S/cm, respectively. Further increasing in the concentration caused a decreasing in the electrical conductivity. Analysis of the thermoelectric properties of the films obtained that the p-type film exhibited significant improvement in its thermoelectric properties, where the thermoelectric properties increased with the increasing of the doping concentration. Meanwhile, for the case of n-type film, graphene doping showed a negative effect to the thermoelectrical properties, where the thermoelectric properties decreased with the increasing of doping concentration. Seebeck coefficient (and power factor) for optimum p-type and n-type hybrid thin films, i.e., doped with 0.08 wt% of graphene, is 20 μV/K (and 160 μW m -1 K -2 ) and 10 μV/K (and 19.5 μW m -1 K -2 ), respectively. The obtained electrical conductivity and thermoelectric properties of graphene-doped hybrid film are interestingly several orders higher than the pristine hybrid films. A thermocouple device fabricated utilizing the p- and n-type graphene-doped hybrid films can generate an electric voltage as high as 2.2 mV under a temperature difference between the hot-side and the cold-side terminal as only low as 55 K. This is equivalent to the output power as high as 24.2 nW (for output load as high as 50

  20. Hemicelluloses/montmorillonite hybrid films with improved mechanical and barrier properties

    Science.gov (United States)

    Chen, Ge-Gu; Qi, Xian-Ming; Li, Ming-Peng; Guan, Ying; Bian, Jing; Peng, Feng; Yao, Chun-Li; Sun, Run-Cang

    2015-11-01

    A facile and environmentally friendly method was introduced to incorporate montmorillonite (MMT) as an inorganic phase into quaternized hemicelluloses (QH) for forming hemicellulose-based films. Two fillers, polyvinyl alcohol (PVA) and chitin nanowhiskers (NCH), were added into the hemicelluloses/MMT hybrid matrices to prepare hybrid films, respectively. The hybrid films were nanocomposites with nacre-like structure and multifunctional characteristics including higher strength and good oxygen barrier properties via the electrostatic and hydrogen bonding interactions. The addition of PVA and NCH could induce changes in surface topography, and effectively enhance mechanical strength, thermal stability, transparency, and oxygen barrier properties. The tensile strengths of the composite films FPVA(0.3), FPVA(0.5), and FNCH(0.8) were 53.7, 46.3, and 50.1 MPa, respectively, which were 171%, 134%, and 153% larger than the FQH-MMT film (19.8 MPa). The tensile strength, and oxygen transmission rate of QH-MMT-PVA film were better than those of quaternized hemicelluloses/MMT films. Thus, the proper filler is very important for the strength of the hybrid film. These results provide insights into the understanding of the structural relationships of hemicellulose-based composite films in coating and packaging application for the future.

  1. Horizontally-connected ZnO-graphene hybrid films for multifunctional devices

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Yi Rang [Thin Film Materials Research Center, Korea Research Institute of Chemical Technology, Yuseong Post Office Box 107, Daejeon 305-600 (Korea, Republic of); School of Semiconductor and Chemical Engineering, Semiconductor Physics Research Center (SPRC), Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Song, Wooseok; Lee, Young Bum; Kim, Seong Ku; Han, Jin Kyu; Myung, Sung; Lee, Sun Sook; An, Ki-Seok [Thin Film Materials Research Center, Korea Research Institute of Chemical Technology, Yuseong Post Office Box 107, Daejeon 305-600 (Korea, Republic of); Choi, Chel-Jong [School of Semiconductor and Chemical Engineering, Semiconductor Physics Research Center (SPRC), Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Lim, Jongsun, E-mail: jslim@krict.re.kr [Thin Film Materials Research Center, Korea Research Institute of Chemical Technology, Yuseong Post Office Box 107, Daejeon 305-600 (Korea, Republic of)

    2016-08-30

    Highlights: • We designed horizontally-connected ZnO and graphene hybrid nanofilms with improved flexibility for multifunctional nanodevices including high performance TFTs. • The photocurrent on-off ratio, response time, and recovery time of the hybrid photodetectors were estimated to be 10{sup 2}, 34 s, and 27 s, respectively. The photocurrent from the hybrid photodetector decreased only by two-fold, whereas a significant decrease in photocurrent by two orders of magnitude was observed from the ZnO thin film based photodetectors after 10{sup 5} cycles of 5-mm radius bending. • The hybrid thin film transistors exhibited unipolar n-channel transistor behavior with electron mobility of 68.7 cm{sup 2}/V s and on-off ratio of 10{sup 7}. - Abstract: Here we designed horizontally-connected ZnO thin films and graphene in order to combine advantages of ZnO thin films, which are high on/off ratio and photo responsivity, and the superior mobility and sensitivity of graphene for applications in thin film transistors (TFTs) and flexible photodetectors. To synthesize the ZnO/graphene hybrid films, a 70-nm-thick ZnO thin film with a uniformly flat surface deposited by the atomic layer deposition process was horizontally connected with highly crystalline monolayer graphene grown by thermal chemical vapor deposition. The photocurrent on-off ratio, response time, and recovery time of the hybrid photodetectors were estimated to be 10{sup 2}, 34 s, and 27 s, respectively. The photocurrent from the hybrid photodetector decreased only by two-fold, whereas a significant decrease in photocurrent by two orders of magnitude was observed from the ZnO thin film based photodetectors after 10{sup 5} cycles of 5-mm radius bending. The hybrid TFT exhibited unipolar n-channel transistor behavior with electron mobility of 68.7 cm{sup 2}/V s and on-off ratio of 10{sup 7}.

  2. Mechanisms involved in the hydrothermal growth of ultra-thin and high aspect ratio ZnO nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Demes, Thomas [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France); Ternon, Céline, E-mail: celine.ternon@grenoble-inp.fr [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France); Univ. Grenoble Alpes, CNRS, LTM, F-38000 Grenoble (France); Morisot, Fanny [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France); Univ. Grenoble Alpes, CNRS, Grenoble-INP" 2, IMEP-LaHC, F-38000 Grenoble (France); Riassetto, David [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France); Legallais, Maxime [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France); Univ. Grenoble Alpes, CNRS, Grenoble-INP" 2, IMEP-LaHC, F-38000 Grenoble (France); Roussel, Hervé; Langlet, Michel [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France)

    2017-07-15

    Highlights: • ZnO nanowires are grown on sol-gel ZnO seed layers by hydrothermal synthesis. • Ultra-thin and high aspect ratio nanowires are obtained without using additives. • Nanowire diameter is 20–25 nm regardless of growth time and seed morphology. • A nanowire growth model is developed on the basis of thermodynamic considerations. • The nanowires are intended for integration into electrically conductive nanonets. - Abstract: Hydrothermal synthesis of ZnO nanowires (NWs) with tailored dimensions, notably high aspect ratios (AR) and small diameters, is a major concern for a wide range of applications and still represents a challenging and recurring issue. In this work, an additive-free and reproducible hydrothermal procedure has been developed to grow ultra-thin and high AR ZnO NWs on sol-gel deposited ZnO seed layers. Controlling the substrate temperature and using a low reagent concentration (1 mM) has been found to be essential for obtaining such NWs. We show that the NW diameter remains constant at about 20–25 nm with growth time contrary to the NW length that can be selectively increased leading to NWs with ARs up to 400. On the basis of investigated experimental conditions along with thermodynamic and kinetic considerations, a ZnO NW growth mechanism has been developed which involves the formation and growth of nuclei followed by NW growth when the nuclei reach a critical size of about 20–25 nm. The low reagent concentration inhibits NW lateral growth leading to ultra-thin and high AR NWs. These NWs have been assembled into electrically conductive ZnO nanowire networks, which opens attractive perspectives toward the development of highly sensitive low-cost gas- or bio-sensors.

  3. Bibliography: Sandia Laboratories hybrid microcircuit and related thin film technology (revised)

    International Nuclear Information System (INIS)

    Oswalt, J.A.

    1975-12-01

    Sandia originated documents (94) describing aspects of technology development related to hybrid microcircuits and thin films are summarized. Authors, titles, and abstracts are given for each unclassified document. The papers are categorized according to the various technologies involved in hybrid microcircuit production

  4. Facile fabrication of boron nitride nanosheets-amorphous carbon hybrid film for optoelectronic applications

    KAUST Repository

    Wan, Shanhong

    2015-01-01

    A novel boron nitride nanosheets (BNNSs)-amorphous carbon (a-C) hybrid film has been deposited successfully on silicon substrates by simultaneous electrochemical deposition, and showed a good integrity of this B-C-N composite film by the interfacial bonding. This synthesis can potentially provide the facile control of the B-C-N composite film for the potential optoelectronic devices. This journal is

  5. Hybrid thin films derived from UV-curable acrylate-modified waterborne polyurethane and monodispersed colloidal silica

    Directory of Open Access Journals (Sweden)

    C. H. Yang

    2012-01-01

    Full Text Available Hybrid thin films containing nano-sized inorganic domains were synthesized from UV-curable acrylate-modified waterborne polyurethane (WPU-AC and monodispersed colloidal silica with coupling agent. The coupling agent, 3-(trimethoxysilylpropyl methacrylate (MSMA, was bonded onto colloidal silica first, and then mixed with WPU-AC to form a precursor solution. This precursor was spin coated, dried and UV-cured to generate the hybrid films. The silica content in the hybrid thin films was varied from 0 to 30 wt%. Experimental results showed the aggregation of silica particles in the hybrid films. Thus, the silica domain in the hybrid films was varied from 30 to 50 nm by the different ratios of MSMAsilica to WPU-AC. The prepared hybrid films from the crosslinked WPU-AC/MSMA-silica showed much better thermal stability and mechanical properties than pure WPU-AC.

  6. Effect of injection parameters on mechanical and physical properties of super ultra-thin wall propylene packaging by Taguchi method

    Science.gov (United States)

    Ginghtong, Thatchanok; Nakpathomkun, Natthapon; Pechyen, Chiravoot

    2018-06-01

    The parameters of the plastic injection molding process have been investigated for the manufacture of a 64 oz. ultra-thin polypropylene bucket. The 3 main parameters, such as injection speed, melting temperature, holding pressure, were investigated to study their effect on the physical appearance and compressive strength. The orthogonal array of Taguchi's L9 (33) was used to carry out the experimental plan. The physical properties were measured and the compressive strength was determined using linear regression analysis. The differential scanning calorimeter (DSC) was used to analyze the crystalline structure of the product. The optimization results show that the proposed approach can help engineers identify optimal process parameters and achieve competitive advantages of energy consumption and product quality. In addition, the injection molding of the product includes 24 mm of shot stroke, 1.47 mm position transfer, 268 rpm screw speed, injection speed 100 mm/s, 172 ton clamping force, 800 kgf holding pressure, 0.9 s holding time and 1.4 s cooling time, make the products in the shape and proportion of the product satisfactory. The parameters of influence are injection speed 71.07%, melting temperature 23.31% and holding pressure 5.62%, respectively. The compressive strength of the product was able to withstand a pressure of up to 839 N before the product became plastic. The low melting temperature was caused by the superior crystalline structure of the super-ultra-thin wall product which leads to a lower compressive strength.

  7. Surface modification of ultra thin PES-zeolite using thermal annealing to increase flux and rejection of produced water treatment

    Energy Technology Data Exchange (ETDEWEB)

    Kusworo, T. D., E-mail: tdkusworo@che.undip.ac.id; Widayat,; Pradini, A. W.; Armeli, Y. P. [Department of Chemical Engineering, University of Diponegoro Prof. Soedarto, Tembalang, Semarang, 50239, Phone/Fax : (024) 7460058 (Indonesia)

    2015-12-29

    Membrane technology is an alternative of water treatment based on filtration that is being developed. Surface Modification using heat treatment has been investigated to improve the performance of ultra thin PES-Zeolite nanocomposite membrane for produced water treatment from Pertamina Balongan. Two types of membranes with surface modification and without modification were prepared to study the effect of surface modification on its permeation properties. Asymmetric ultra thin PES-Zeolite nanocomposite membrane for produced water treatment was casted using the dry/wet phase inversion technique from dope solutions containing polyethersulfone, N-methyl-2-pyrrolidone (NMP) as a solvent and zeolite as a filler. Experimental results showed that the heat treatment at near glass transition temperature was increase the rejection of COD, Turbidity and ion Ca{sup 2+}. The better adherence of zeolite particles in the polymer matrix combined with formation of charge transfer complexes (CTCs) and cross-linking might be the main factors to enhance the percent of rejection. Field emission scanning electron microscopy (FESEM) micrographs showed that the selective layer and the substructure of PES-zeolite membrane became denser and more compact after the heat treatment. The FESEM micrographs also showed that the heat treatment was increased the adherence of zeolite particle and polymer. Membranes treated at 180 °C for 15 seconds indicated increase the rejection and small decrease in flux for produced water treatment.

  8. Synthesis of ultra-thin tellurium nanoflakes on textiles for high-performance flexible and wearable nanogenerators

    Energy Technology Data Exchange (ETDEWEB)

    He, Wen; Van Ngoc, Huynh; Qian, Yong Teng; Hwang, Jae Seok; Yan, Ya Ping [Department of Physics and Interdisciplinary Course of Physics and Chemistry, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon 16419, Gyeoggi-do (Korea, Republic of); Choi, Hongsoo [Department of Robotics Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 711-873, Daegu (Korea, Republic of); Kang, Dae Joon, E-mail: djkang@skku.edu [Department of Physics and Interdisciplinary Course of Physics and Chemistry, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon 16419, Gyeoggi-do (Korea, Republic of)

    2017-01-15

    Highlights: • Ultra-thin tellurium (Te) nanoflakes were successfully grown on textile and used as an active piezoelectric material. • Te nanoflake nanogenerator device was systematically studied by bending and compressing test. • The ultra-high output power during compressing test can light up 10 LEDs without any external power source. • The device can offer a breakthrough in applying tellurium nanoflakes into high-performance flexible and wearable piezoelectric nanogenerator. - Abstract: We report that ultra-thin tellurium (Te) nanoflakes were successfully grown on a sample of a gold-coated textile, which then was used as an active piezoelectric material. An output voltage of 4 V and a current of 300 nA were obtained from the bending test under a driving frequency of 10 Hz. To test the practical applications, Te nanoflake nanogenerator (TFNG) device was attached to the subject’s arm, and mechanical energy was converted to electrical energy by means of periodic arm-bending motions. The optimized open-circuit voltage and short-circuit current density of approximately 125 V and 17 μA/cm{sup 2}, respectively, were observed when a TFNG device underwent a compression test with a compressive force of 8 N and driving frequency of 10 Hz. This high-power generation enabled the instantaneous powering of 10 green light-emitting diodes that shone without any assistance from an external power source.

  9. Optical spin-to-orbital angular momentum conversion in ultra-thin metasurfaces with arbitrary topological charges

    Energy Technology Data Exchange (ETDEWEB)

    Bouchard, Frédéric; De Leon, Israel; Schulz, Sebastian A.; Upham, Jeremy; Karimi, Ebrahim, E-mail: ekarimi@uottawa.ca [Department of Physics, University of Ottawa, 25 Templeton, Ottawa, Ontario K1N 6N5 Canada (Canada); Boyd, Robert W. [Department of Physics, University of Ottawa, 25 Templeton, Ottawa, Ontario K1N 6N5 Canada (Canada); Institute of Optics, University of Rochester, Rochester, New York 14627 (United States)

    2014-09-08

    Orbital angular momentum associated with the helical phase-front of optical beams provides an unbounded “space” for both classical and quantum communications. Among the different approaches to generate and manipulate orbital angular momentum states of light, coupling between spin and orbital angular momentum allows a faster manipulation of orbital angular momentum states because it depends on manipulating the polarisation state of light, which is simpler and generally faster than manipulating conventional orbital angular momentum generators. In this work, we design and fabricate an ultra-thin spin-to-orbital angular momentum converter, based on plasmonic nano-antennas and operating in the visible wavelength range that is capable of converting spin to an arbitrary value of orbital angular momentum ℓ. The nano-antennas are arranged in an array with a well-defined geometry in the transverse plane of the beam, possessing a specific integer or half-integer topological charge q. When a circularly polarised light beam traverses this metasurface, the output beam polarisation switches handedness and the orbital angular momentum changes in value by ℓ=±2qℏ per photon. We experimentally demonstrate ℓ values ranging from ±1 to ±25 with conversion efficiencies of 8.6% ± 0.4%. Our ultra-thin devices are integratable and thus suitable for applications in quantum communications, quantum computations, and nano-scale sensing.

  10. Mechanisms involved in the hydrothermal growth of ultra-thin and high aspect ratio ZnO nanowires

    Science.gov (United States)

    Demes, Thomas; Ternon, Céline; Morisot, Fanny; Riassetto, David; Legallais, Maxime; Roussel, Hervé; Langlet, Michel

    2017-07-01

    Hydrothermal synthesis of ZnO nanowires (NWs) with tailored dimensions, notably high aspect ratios (AR) and small diameters, is a major concern for a wide range of applications and still represents a challenging and recurring issue. In this work, an additive-free and reproducible hydrothermal procedure has been developed to grow ultra-thin and high AR ZnO NWs on sol-gel deposited ZnO seed layers. Controlling the substrate temperature and using a low reagent concentration (1 mM) has been found to be essential for obtaining such NWs. We show that the NW diameter remains constant at about 20-25 nm with growth time contrary to the NW length that can be selectively increased leading to NWs with ARs up to 400. On the basis of investigated experimental conditions along with thermodynamic and kinetic considerations, a ZnO NW growth mechanism has been developed which involves the formation and growth of nuclei followed by NW growth when the nuclei reach a critical size of about 20-25 nm. The low reagent concentration inhibits NW lateral growth leading to ultra-thin and high AR NWs. These NWs have been assembled into electrically conductive ZnO nanowire networks, which opens attractive perspectives toward the development of highly sensitive low-cost gas- or bio-sensors.

  11. Optical spin-to-orbital angular momentum conversion in ultra-thin metasurfaces with arbitrary topological charges

    International Nuclear Information System (INIS)

    Bouchard, Frédéric; De Leon, Israel; Schulz, Sebastian A.; Upham, Jeremy; Karimi, Ebrahim; Boyd, Robert W.

    2014-01-01

    Orbital angular momentum associated with the helical phase-front of optical beams provides an unbounded “space” for both classical and quantum communications. Among the different approaches to generate and manipulate orbital angular momentum states of light, coupling between spin and orbital angular momentum allows a faster manipulation of orbital angular momentum states because it depends on manipulating the polarisation state of light, which is simpler and generally faster than manipulating conventional orbital angular momentum generators. In this work, we design and fabricate an ultra-thin spin-to-orbital angular momentum converter, based on plasmonic nano-antennas and operating in the visible wavelength range that is capable of converting spin to an arbitrary value of orbital angular momentum ℓ. The nano-antennas are arranged in an array with a well-defined geometry in the transverse plane of the beam, possessing a specific integer or half-integer topological charge q. When a circularly polarised light beam traverses this metasurface, the output beam polarisation switches handedness and the orbital angular momentum changes in value by ℓ=±2qℏ per photon. We experimentally demonstrate ℓ values ranging from ±1 to ±25 with conversion efficiencies of 8.6% ± 0.4%. Our ultra-thin devices are integratable and thus suitable for applications in quantum communications, quantum computations, and nano-scale sensing.

  12. Organic-inorganic hybrid materials as semiconducting channels in thin-film field-effect transistors

    Science.gov (United States)

    Kagan; Mitzi; Dimitrakopoulos

    1999-10-29

    Organic-inorganic hybrid materials promise both the superior carrier mobility of inorganic semiconductors and the processability of organic materials. A thin-film field-effect transistor having an organic-inorganic hybrid material as the semiconducting channel was demonstrated. Hybrids based on the perovskite structure crystallize from solution to form oriented molecular-scale composites of alternating organic and inorganic sheets. Spin-coated thin films of the semiconducting perovskite (C(6)H(5)C(2)H(4)NH(3))(2)SnI(4) form the conducting channel, with field-effect mobilities of 0.6 square centimeters per volt-second and current modulation greater than 10(4). Molecular engineering of the organic and inorganic components of the hybrids is expected to further improve device performance for low-cost thin-film transistors.

  13. Electrocatalytic behaviour of hybrid cobalt–manganese hexacyanoferrate film on glassy carbon electrode

    International Nuclear Information System (INIS)

    Vinu Mohan, A.M.; Rambabu, Gutru; Aswini, K.K.; Biju, V.M.

    2014-01-01

    A thin film of hybrid cobalt–manganese hexacyanoferrate (CoMnHCF), a redox mediator was electrodeposited on a glassy carbon (GC) electrode and was employed as an amperometric sensor towards L-Tryptophan (L-Trp). The hybrid film was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction technique (XRD), scanning electron microscope–energy dispersive X-ray spectroscopy (SEM–EDAX), and electrochemical techniques. The atomic absorption spectroscopic analysis provided the stoichiometry of the hybrid film to be K 1.74-y Co y Mn 0.78 [Fe(CN) 6 ], y ≤ 0.68. The electrochemical impedance study revealed the excellent charge transfer properties of GC/CoMnHCF electrode. The voltammetric investigations demonstrated exceptional electrocatalytic properties of the hybrid film modified electrode when compared to that of bare GC, GC/CoHCF and GC/MnHCF electrodes, towards the L-Trp oxidation. The kinetic parameters such as electron transfer coefficient, the electron transfer rate constant, the diffusion coefficient and the catalytic rate constant for the electrooxidation process of L-Trp were investigated. The amperometric detection of L-Trp employing GC/CoMnHCF electrode possessed a good sensitivity of 10 × 10 −2 A M −1 cm −2 in a wide range of detection (2–200 μM) at a reduced overpotential of 680 mV. In addition, the proposed amperometric method was applied to the detection of L-Trp in commercial milk samples with reproducible results. - Highlights: • A hybrid cobalt–manganese hexacyanoferrate film was prepared. • The hybrid film possesses excellent charge transfer properties. • The hybrid film exhibits excellent electrocatalytic properties towards Tryptophan. • Tryptophan detection is possible from commercial milk samples

  14. Role of direct covalent bonding in enhanced heat dissipation property of flexible graphene oxide–carbon nanotube hybrid film

    International Nuclear Information System (INIS)

    Hwang, Yongseon; Kim, Myeongjin; Kim, Jooheon

    2013-01-01

    The thermal conductivity of graphene oxide/multiwalled carbon nanotube (GO/MWCNT) hybrid films with and without covalent bonding is examined in this study. To fabricate chemically bonded GO/MWCNT hybrid films, chlorinated GO and amino-functionalized MWCNTs are bonded covalently. The mixtures of surface modified GO and MWCNT were filtered and then subjected to hot pressing to fabricate stacked films. Examination of these chemically bonded hybrid films reveal that chlorine-doped GO exhibits enhanced electrical properties because it creates hole charge carriers by attracting the electrons in GO towards chlorine. Enhanced electrical conductivity and low sheet resistance are observed also with increasing MWCNT loadings. On comparing the through-plane thermal properties, the chemically bonded hybrid films were found to exhibit higher thermal conductivity than do the physically bonded hybrid films because of the synergetic interaction of functional groups in GO and MWCNTs in the former films. However, excess addition of MWCNTs to the films leads to an increasing phonon scattering density and a decreased thermal conductivity. - Highlights: • Graphene oxide/carbon nanotube (GO/CNT) films are bonded covalently. • GO/CNT hybrid films are prepared through filtering and hot-pressing method. • Chemically bonded hybrid films exhibit enhanced electrical and thermal properties. • Enhanced thermal conductivity is explained according to increasing CNT contents

  15. Fabrication of molecular hybrid films of gold nanoparticle and polythiophene by covalent assembly

    Energy Technology Data Exchange (ETDEWEB)

    Sundaramurthy, Jayaraman, E-mail: jsu2@np.edu.sg [Department of Chemical & Biomolecular Engineering, National University of Singapore, Block E5, 4 Engineering Drive 4, 117576 (Singapore); Environmental & Water Technology Centre of Innovation, Ngee Ann Polytechnic, 599489 (Singapore); Dharmarajan, Rajarathnam [CERAR, University of South Australia, Mawson Lakes, SA 5095 (Australia); Srinivasan, M.P., E-mail: chesmp@nus.edu.sg [Department of Chemical & Biomolecular Engineering, National University of Singapore, Block E5, 4 Engineering Drive 4, 117576 (Singapore)

    2015-08-31

    This work demonstrates the fabrication of molecular hybrid films comprising gold nanoparticles (AuNPs) incorporated in covalently assembled, substituted polythiophene (poly(3-(2-bromoethoxy)ethoxymethylthiophene-2,5-diyl (PBrEEMT))) films by different surface chemistry routes. AuNPs are incorporated in the immobilized polythiophene matrix due to its affinity for amine and sulfur. The amount of AuNPs present depends on the nature of the incorporation, the extent of film coverage and interaction of thiophene and amine groups. PBrEEMT films functionalized with amine rich polyallylamine immobilize greater numbers of AuNPs due to more extensive gold–amine interactions. Covalent binding between AuNP and PBrEEMT films was accomplished by using pre-functionalised AuNPs (4-aminothiophenol functionalized AuNPs). Atomic force microscopy, field emission scanning electron microscopy and X-ray photoelectron spectroscopy were used to study the morphology and chemical constituents of assembled films. These approaches will pave the way for developing facile methods for nanoparticle incorporation and will also facilitate direct interaction of nanoparticles with the conducting polymer matrix and enhance the electrical properties of the films. - Highlights: • Covalent molecular assembly enabled the fabrication of molecular hybrid films. • Monomeric and polymeric species were employed as intermediate linkers. • Adopted approaches facilitated the direct interaction of gold nanoparticle in films. • The amount of nanoparticle incorporation depended on the extent of film coverage.

  16. Cage and linear structured polysiloxane/epoxy hybrids for coatings: Surface property and film permeability.

    Science.gov (United States)

    Ma, Yanli; He, Ling; Jia, Mengjun; Zhao, Lingru; Zuo, Yanyan; Hu, Pingan

    2017-08-15

    Three polysiloxane/epoxy hybrids obtained by evolving cage- or linear-structured polysiloxane into poly glycidyl methacrylate (PGMA) matrix are compared used as coatings. One is the cage-structured hybrid of P(GMA/MA-POSS) copolymer obtained by GMA and methacrylisobutyl polyhedral oligomeric silsesquioxane (MA-POSS) via free radical polymerization, the other two are PGMA/NH 2 -POSS and PGMA/NH 2 -PDMS hybrids by cage-structured aminopropyllsobutyl POSS (NH 2 -POSS) or linear-structured diamino terminated poly(dimethylsiloxane) (NH 2 -PDMS) to cure PGMA. The effect of MA-POSS, NH 2 -POSS and NH 2 -PDMS on polysiloxane/epoxy hybrid films is characterized according to their surface morphology, transparency, permeability, adhesive strength and thermo-mechanical properties. Due to caged POSS tending to agglomerate onto the film surface, P(GMA/MA-POSS) and PGMA/NH 2 -POSS films exhibit much more heterogeneous surfaces than PGMA/NH 2 -PDMS film, but the well-compatibility between epoxy matrix and MA-POSS has provided P(GMA/MA-POSS) film with much higher transmittance (98%) than PGMA/NH 2 -POSS film (24%), PGMA/NH 2 -PDMS film (27%) and traditional epoxy resin film (5%). The introduction of polysiloxane into epoxy matrix is confirmed to create hybrids with strong adhesive strength (526-1113N) and high thermos-stability (T g =262-282°C), especially the cage-structured P(GMA/MA-POSS) hybrid (1113N and 282°C), but the flexible PDMS improves PGMA/NH 2 -PDMS hybrid with much higher storage modulus (519MPa) than PGMA/NH 2 -POSS (271MPa), which suggests that PDMS is advantage in improving the film stiffness than POSS cages. However, cage-structured P(GMA/MA-POSS) and PGMA/NH 2 -POSS indicate higher permeability than PGMA/NH 2 -PDMS and traditional epoxy resin. Comparatively, the cage-structured P(GMA/MA-POSS) hybrid is the best coating in transparency, permeability, adhesive strength and thermostability, but linear-structured PGMA/NH 2 -PDMS hybrid behaviors the best coating in

  17. In-situ spectroscopic ellipsometry for studies of thin films and membranes

    NARCIS (Netherlands)

    Ogieglo, Wojciech

    2014-01-01

    The properties of a thin polymer film can be significantly affected by the presence of a penetrant. It is also known that the behavior of ultra-thin polymer films (<100 nm) may deviate from the bulk behavior. This sole impact of film thickness reduction is often referred to as a nano-confinement

  18. Photoelectrochemical Cell of Hybrid Regioregular POLY(3-HEXYLTHIOPHENE-2,5-DIYL) and Molybdenum Disulfide Film

    Science.gov (United States)

    Abdelmola, Fatmaelzahraa M.; Ram, Manoj K.; Takshi, Arash; Stafanakos, Elias; Kumar, Ashok; Goswami, D. Yogi

    The photoelectrochemical cell attracts attention worldwide due to conversion of optical energy into electricity, production of hydrogen through water splitting and use in photodetector and photo-sensor applications. We have been working on the photochemical cell based on regioregular polyhexylthiophenes hybrid-structured films for photoelectrochemical and photovoltaic applications. This paper discusses the hybrid film studies on regioregular poly(3-hexylthiophene-2,5-diyl) (P3HT) with 2D molybdenum disulfide (MoS2) for photoelectrochemical cell. The hybrid P3HT/MoS2 films deposited over indium tin oxide (ITO)-coated glass plate or n-type silicon substrates were characterized using FTIR, UV/vis, electrochemical and scanning electron microscopy (SEM) techniques. The optical measurements showed a higher absorption magnitude with low reflection properties of P3HT/MoS2 hybrid films revealing a superior photocurrent compared to both P3HT and MoS2 films. The P3HT/MoS2 hybrid-based photoelectrochemical cell yielded a short-circuit current (Isc) of 183.16μAṡcm-2, open-circuit voltage (Voc) of 0.92V, fill factor (FF) of 25% and power conversion efficiency (η) of 0.18% under the light intensity of 242Wṡm-2. The estimated power conversion efficiency and fill factor are comparable to organic-based photovoltaic devices.

  19. MgB2 thin films by hybrid physical-chemical vapor deposition

    International Nuclear Information System (INIS)

    Xi, X.X.; Pogrebnyakov, A.V.; Xu, S.Y.; Chen, K.; Cui, Y.; Maertz, E.C.; Zhuang, C.G.; Li, Qi; Lamborn, D.R.; Redwing, J.M.; Liu, Z.K.; Soukiassian, A.; Schlom, D.G.; Weng, X.J.; Dickey, E.C.; Chen, Y.B.; Tian, W.; Pan, X.Q.; Cybart, S.A.; Dynes, R.C.

    2007-01-01

    Hybrid physical-chemical vapor deposition (HPCVD) has been the most effective technique for depositing MgB 2 thin films. It generates high magnesium vapor pressures and provides a clean environment for the growth of high purity MgB 2 films. The epitaxial pure MgB 2 films grown by HPCVD show higher-than-bulk T c due to tensile strain in the films. The HPCVD films are the cleanest MgB 2 materials reported, allowing basic research, such as on magnetoresistance, that reveals the two-band nature of MgB 2 . The carbon-alloyed HPCVD films demonstrate record-high H c2 values promising for high magnetic field applications. The HPCVD films and multilayers have enabled the fabrication of high quality MgB 2 Josephson junctions

  20. Controlled fabrication of PANI/CNF hybrid films: molecular interaction induced various micromorphologies and electrochemical properties.

    Science.gov (United States)

    Xu, Guiheng; Xu, Dongdong; Zhang, Jianan; Wang, Kaixi; Chen, Zhimin; Chen, Jiafu; Xu, Qun

    2013-12-01

    In this paper, a facile and efficient method is reported to prepare polyaniline/carbon nanofiber (PANI/CNF) hybrid films by in situ chemical polymerization of aniline. The various morphologies and microstructures of PANI/CNF hybrid films can be controlled by adjusting the concentration of aniline and different acids as the protonation reagent, and the formation mechanism is illustrated in this study. The surface morphologies and chemical structure of the PANI/CNF hybrid films are characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), water contact angle (CA), FT-IR, Raman, and UV-vis spectrophotometers. The different morphology of uniformly coated, twist-tangled, and needle-like PANI built on CNF films are obtained by using HCl, H2SO4, and HClO4 as protonation reagent and the obtained hybrid films are labeled as PANI/CNF-f1, PANI/CNF-f2, and PANI/CNF-f3, respectively. We demonstrated that the different protonation reagent has the determined effect on the surface properties of the obtained hybrid films that can transfer from hydrophilic to hydrophobic. Besides, the various morphologies of PANI play an important role in their electrochemical properties. PANI/CNF-f3 exhibits higher specific capacitance and better stability than that of the PANI/CNF-f1 and PANI/CNF-f2. Considering its unique needle-like structure, this work is a proof of concept that micro-structure and morphology can determine the macro-properties. And this study supplies a facile method to fabricate PANI/CNF hybrid films that can be used as electrode materials in supercapacitors. Copyright © 2013 Elsevier Inc. All rights reserved.

  1. Preparation and antibacterial properties of hybrid-zirconia films with silver nanoparticles

    International Nuclear Information System (INIS)

    Azócar, Ignacio; Vargas, Esteban; Duran, Nicole; Arrieta, Abel; González, Evelyn

    2012-01-01

    The antimicrobial effect of incorporating silver nanoparticles (AgNps) into zirconia matrix–polyether glycol was studied. AgNps of 4–6 nm in size were synthesized using the inverse micelles method, and different doses of metallic nanoparticles were incorporated into zirconia–polyether glycol mixtures during the ageing procedure. Atomic force microscopy (AFM) of the modified hybrid film showed a homogenous distribution of 20–80 nm diameter AgNps, indicating agglomeration of these structures during film modification; such agglomerations were greater when increasing the dosage of the colloidal system. The AgNps-hybrid films showed higher antimicrobial activity against Gram-positive bacteria than for Gram-negative bacteria. Hybrid films prepared with dioctyl sodium sulfosuccinate (AOT) stabilized AgNps presented enhanced antibacterial activity compared to that obtained through the addition of a high AgNO 3 concentration (0.3 wt%). -- Graphical abstract: Atomic Force Micrographs, top and cross section view, showing silver nanoparticles embedded in a zirconia–polyether glycol hybrid film. Highlights: ► Antibacterial activity of films (zirconia–polyether glycol) modified with silver nanoparticles. ► Biofilm formation is prevented. ► High sensibility against gram positive bacteria.

  2. Preparation and antibacterial properties of hybrid-zirconia films with silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Azocar, Ignacio, E-mail: manuel.azocar@usach.cl [Departamento de Quimica de los Materiales, Facultad de Quimica y Biologia, Universidad de Santiago de Chile, USACH, Avenida Bernardo O' Higgins 3363, Casilla 40, Correo 33, Santiago (Chile); Vargas, Esteban [Facultad de Ingenieria, Departamento de Metalurgia, Universidad de Santiago de Chile, USACH (Chile); Duran, Nicole [Departamento de Quimica de los Materiales, Facultad de Quimica y Biologia, Universidad de Santiago de Chile, USACH, Avenida Bernardo O' Higgins 3363, Casilla 40, Correo 33, Santiago (Chile); Arrieta, Abel [Departamento de Biologia, Facultad de Quimica y Biologia, Universidad de Santiago de Chile, USACH (Chile); Gonzalez, Evelyn [Departamento de Quimica de los Materiales, Facultad de Quimica y Biologia, Universidad de Santiago de Chile, USACH, Avenida Bernardo O' Higgins 3363, Casilla 40, Correo 33, Santiago (Chile); Facultad de Ingenieria, Departamento de Metalurgia, Universidad de Santiago de Chile, USACH (Chile); Departamento de Biologia, Facultad de Quimica y Biologia, Universidad de Santiago de Chile, USACH (Chile); Departamento de Quimica Farmacologica y Toxicologica, Facultad de Ciencias Quimicas, Universidad de Chile, Sergio Livingstone Polhammer 1007, Santiago (Chile); and others

    2012-11-15

    The antimicrobial effect of incorporating silver nanoparticles (AgNps) into zirconia matrix-polyether glycol was studied. AgNps of 4-6 nm in size were synthesized using the inverse micelles method, and different doses of metallic nanoparticles were incorporated into zirconia-polyether glycol mixtures during the ageing procedure. Atomic force microscopy (AFM) of the modified hybrid film showed a homogenous distribution of 20-80 nm diameter AgNps, indicating agglomeration of these structures during film modification; such agglomerations were greater when increasing the dosage of the colloidal system. The AgNps-hybrid films showed higher antimicrobial activity against Gram-positive bacteria than for Gram-negative bacteria. Hybrid films prepared with dioctyl sodium sulfosuccinate (AOT) stabilized AgNps presented enhanced antibacterial activity compared to that obtained through the addition of a high AgNO{sub 3} concentration (0.3 wt%). -- Graphical abstract: Atomic Force Micrographs, top and cross section view, showing silver nanoparticles embedded in a zirconia-polyether glycol hybrid film. Highlights: Black-Right-Pointing-Pointer Antibacterial activity of films (zirconia-polyether glycol) modified with silver nanoparticles. Black-Right-Pointing-Pointer Biofilm formation is prevented. Black-Right-Pointing-Pointer High sensibility against gram positive bacteria.

  3. The TDDB Characteristics of Ultra-Thin Gate Oxide MOS Capacitors under Constant Voltage Stress and Substrate Hot-Carrier Injection

    Directory of Open Access Journals (Sweden)

    Jingyu Shen

    2018-01-01

    Full Text Available The breakdown characteristics of ultra-thin gate oxide MOS capacitors fabricated in 65 nm CMOS technology under constant voltage stress and substrate hot-carrier injection are investigated. Compared to normal thick gate oxide, the degradation mechanism of time-dependent dielectric breakdown (TDDB of ultra-thin gate oxide is found to be different. It is found that the gate current (Ig of ultra-thin gate oxide MOS capacitor is more likely to be induced not only by Fowler-Nordheim (F-N tunneling electrons, but also by electrons surmounting barrier and penetrating electrons in the condition of constant voltage stress. Moreover it is shown that the time to breakdown (tbd under substrate hot-carrier injection is far less than that under constant voltage stress when the failure criterion is defined as a hard breakdown according to the experimental results. The TDDB mechanism of ultra-thin gate oxide will be detailed. The differences in TDDB characteristics of MOS capacitors induced by constant voltage stress and substrate hot-carrier injection will be also discussed.

  4. Effects of Cold Rolling Reduction and Initial Goss Grains Orientation on Texture Evolution and Magnetic Performance of Ultra-thin Grain-oriented Silicon Steel

    Directory of Open Access Journals (Sweden)

    LIANG Rui-yang

    2017-06-01

    Full Text Available The ultra-thin grain-oriented silicon steel strips with a thickness of 0.06-0.12mm were produced by one-step-rolling methods with different Goss-orientation of grain-oriented silicon steel sheets. The effect of cold rolling reduction and initial Goss-orientation of samples on texture evolution and magnetic performance of ultra-thin grain-oriented silicon steel strips was studied by EBSD. The result shows that with the increase of cold rolling reduction and decrease of strips thickness, the recrystallization texture is enhanced after annealing.When the cold rolling reduction is 70%,RD//〈001〉 recrystallization texture is the sharpest, and the magnetic performance is the best. The higher degree of Goss orientation in initial sample is, the better magnetic performance of ultra-thin grain-oriented silicon steel.Therefore, for producing an ultra-thin grain-oriented silicon steel with high performance, a material with a concentrated orientation of Goss grains can be used.

  5. Hybrid composite thin films composed of tin oxide nanoparticles and cellulose

    International Nuclear Information System (INIS)

    Mahadeva, Suresha K; Nayak, Jyoti; Kim, Jaehwan

    2013-01-01

    This paper reports the preparation and characterization of hybrid thin films consisting of tin oxide (SnO 2 ) nanoparticles and cellulose. SnO 2 nanoparticle loaded cellulose hybrid thin films were fabricated by a solution blending technique, using sodium dodecyl sulfate as a dispersion agent. Scanning and transmission electron microscopy studies revealed uniform dispersion of the SnO 2 nanoparticles in the cellulose matrix. Reduction in the crystalline melting transition temperature and tensile properties of cellulose was observed due to the SnO 2 nanoparticle loading. Potential application of these hybrid thin films as low cost, flexible and biodegradable humidity sensors is examined in terms of the change in electrical resistivity of the material exposed to a wide range of humidity as well as its response–recovery behavior. (paper)

  6. Realization of dual-heterojunction solar cells on ultra-thin ∼25 μm, flexible silicon substrates

    KAUST Repository

    Onyegam, Emmanuel U.; Sarkar, Dabraj; Hilali, Mohamed M.; Saha, Sayan; Mathew, Leo; Rao, Rajesh A.; Smith, Ryan S.; Xu, Dewei; Jawarani, Dharmesh; Garcia, Ricardo; Ainom, Moses; Banerjee, Sanjay K.

    2014-01-01

    Silicon heterojunction (HJ) solar cells with different rear passivation and contact designs were fabricated on ∼ 25 μ m semiconductor-on-metal (SOM) exfoliated substrates. It was found that the performance of these cells is limited by recombination at the rear-surface. Employing the dual-HJ architecture resulted in the improvement of open-circuit voltage (Voc) from 605 mV (single-HJ) to 645 mV with no front side intrinsic amorphous silicon (i-layer) passivation. Addition of un-optimized front side i-layer passivation resulted in further enhancement in Voc to 662 mV. Pathways to achieving further improvement in the performance of HJ solar cells on ultra-thin SOM substrates are discussed. © 2014 AIP Publishing LLC.

  7. Congenital cheek teratoma with temporo-mandibular joint ankylosis managed with ultra-thin silicone sheet interpositional arthroplasty.

    Science.gov (United States)

    Bhatnagar, Ankur; Verma, Vinay Kumar; Purohit, Vishal

    2013-01-01

    Primary cheek teratomas are rare with joint ankylosis (TMJA). The fundamental aim in the treatment of TMJA is the successful surgical resection of ankylotic bone, prevention of recurrence, and aesthetic improvement by ensuring functional occlusion. Early treatment is necessary to promote proper growth and function of mandible and to facilitate the positive psychological development of child. Inter-positional arthroplasty with ultra-thin silicone sheet was performed. Advantages include short operative time, less foreign material in the joint space leading to negligible foreign body reactions and least chances of implant extrusion. Instead of excising a large bony segment, a thin silicone sheet was interposed and then sutured ensuring preservation of mandibular height. Aggressive post-operative physiotherapy with custom made dynamic jaw exerciser was used to prevent recurrence.

  8. Ultra-thin layer chromatography and surface enhanced Raman spectroscopy on silver nanorod array substrates prepared by oblique angle deposition

    Science.gov (United States)

    Chen, Jing; Abell, Justin; Huang, Yao-wen; Zhao, Yiping

    2012-06-01

    We demonstrate the potential use of silver nanorod (AgNR) array substrates for on-chip separation and detection of chemical mixtures by ultra-thin layer chromatography (UTLC) and surface enhanced Raman spectroscopy (SERS). The capability of the AgNR substrates to separate different compounds in a mixture was explored using a mixture of the food colorant Brilliant Blue FCF and lactic acid, and the mixtures of Methylene Violet and BSA at various concentrations. After the UTLC process, spatially-resolved SERS spectra were collected along the mobile phase development direction and the intensities of specific SERS peaks from each component were used to generate chromatograms. The AgNR substrates demonstrate the capability of separating Brilliant Blue from lactic acid, as well as revealing the SERS signal of Methylene Violet from the massive BSA background after a simple UTLC step. This technique may have significant practical implications in actual detection of small molecules from complex food or clinical backgrounds.

  9. Realization of dual-heterojunction solar cells on ultra-thin ∼25 μm, flexible silicon substrates

    KAUST Repository

    Onyegam, Emmanuel U.

    2014-04-14

    Silicon heterojunction (HJ) solar cells with different rear passivation and contact designs were fabricated on ∼ 25 μ m semiconductor-on-metal (SOM) exfoliated substrates. It was found that the performance of these cells is limited by recombination at the rear-surface. Employing the dual-HJ architecture resulted in the improvement of open-circuit voltage (Voc) from 605 mV (single-HJ) to 645 mV with no front side intrinsic amorphous silicon (i-layer) passivation. Addition of un-optimized front side i-layer passivation resulted in further enhancement in Voc to 662 mV. Pathways to achieving further improvement in the performance of HJ solar cells on ultra-thin SOM substrates are discussed. © 2014 AIP Publishing LLC.

  10. Planar ultra thin glass seals with optical fiber interface for monitoring tamper attacks on security eminent components

    Science.gov (United States)

    Thiel, M.; Flachenecker, G.; Schade, W.; Gorecki, C.; Thoma, A.; Rathje, R.

    2017-11-01

    Optical seals consisting of waveguide Bragg grating sensor structures in ultra thin glass transparencies have been developed to cover security relevant objects for detection of unauthorized access. For generation of optical signature in the seals, femtosecond laser pulses were used. The optical seals were connected with an optical fiber to enable external read out of the seal. Different attack scenarios for getting undetected access to the object, covered by the seal, were proven and evaluated. The results presented here, verify a very high level of security. An unauthorized detaching and subsequent replacement by original or copy of the seals for tampering would be accompanied with a very high technological effort, posing a substantial barrier towards an attacker. Additionally, environmental influences like temperature effects have a strong but reproducible influence on signature, which in context of a temperature reference database increases the level of security significantly.

  11. 3D lumped components and miniaturized bandpass filter in an ultra-thin M-LCP for SOP applications

    KAUST Repository

    Arabi, Eyad A.

    2013-01-01

    In this work, a library of 3D lumped components completely embedded in the thinnest, multilayer LCP (M-LCP) stack- up with four metallization layers and 100 μm of total thickness, is reported for the first time. A vertically and horizontally interdigitated capacitor, realized in this stack-up, provides higher self resonant frequency as compared to a similarly sized conventional parallel plate capacitor. Based on the above mentioned library, a miniaturized bandpass filter is presented for the GPS application. It utilizes mutually coupled inductors and is the smallest reported in the literature with a size of (0.035×0.028×0.00089)λg. Finally, the same filter realized in a competing ceramic technology (LTCC) is compared in performance with the ultra-thin M-LCP design. The M-LCP module presented in this work is inherently exible and offers great potential for wearable and conformal applications.

  12. Well-constructed cellulose acetate membranes for forward osmosis: Minimized internal concentration polarization with an ultra-thin selective layer

    KAUST Repository

    Zhang, Sui

    2010-09-01

    The design and engineering of membrane structure that produces low salt leakage and minimized internal concentration polarization (ICP) in forward osmosis (FO) processes have been explored in this work. The fundamentals of phase inversion of cellulose acetate (CA) regarding the formation of an ultra-thin selective layer at the bottom interface of polymer and casting substrate were investigated by using substrates with different hydrophilicity. An in-depth understanding of membrane structure and pore size distribution has been elucidated with field emission scanning electronic microscopy (FESEM) and positron annihilation spectroscopy (PAS). A double dense-layer structure is formed when glass plate is used as the casting substrate and water as the coagulant. The thickness of the ultra-thin bottom layer resulted from hydrophilic-hydrophilic interaction is identified to be around 95nm, while a fully porous, open-cell structure is formed in the middle support layer due to spinodal decomposition. Consequently, the membrane shows low salt leakage with mitigated ICP in the FO process for seawater desalination. The structural parameter (St) of the membrane is analyzed by modeling water flux using the theory that considers both external concentration polarization (ECP) and ICP, and the St value of the double dense-layer membrane is much smaller than those reported in literatures. Furthermore, the effects of an intermediate immersion into a solvent/water mixed bath prior to complete immersion in water on membrane formation have been studied. The resultant membranes may have a single dense layer with an even lower St value. A comparison of fouling behavior in a simple FO-membrane bioreactor (MBR) system is evaluated for these two types of membranes. The double dense-layer membrane shows a less fouling propensity. This study may help pave the way to improve the membrane design for new-generation FO membranes. © 2010 Elsevier B.V.

  13. Transparent Conducting Graphene Hybrid Films To Improve Electromagnetic Interference (EMI) Shielding Performance of Graphene.

    Science.gov (United States)

    Ma, Limin; Lu, Zhengang; Tan, Jiubin; Liu, Jian; Ding, Xuemei; Black, Nicola; Li, Tianyi; Gallop, John; Hao, Ling

    2017-10-04

    Conducting graphene-based hybrids have attracted considerable attention in recent years for their scientific and technological significance in many applications. In this work, conductive graphene hybrid films, consisting of a metallic network fully encapsulated between monolayer graphene and quartz-glass substrate, were fabricated and characterized for their electromagnetic interference shielding capabilities. Experimental results show that by integration with a metallic network the sheet resistance of graphene was significantly suppressed from 813.27 to 5.53 Ω/sq with an optical transmittance at 91%. Consequently, the microwave shielding effectiveness (SE) exceeded 23.60 dB at the K u -band and 13.48 dB at the K a -band. The maximum SE value was 28.91 dB at 12 GHz. Compared with the SE of pristine monolayer graphene (3.46 dB), the SE of graphene hybrid film was enhanced by 25.45 dB (99.7% energy attenuation). At 94% optical transmittance, the sheet resistance was 20.67 Ω/sq and the maximum SE value was 20.86 dB at 12 GHz. Our results show that hybrid graphene films incorporate both high conductivity and superior electromagnetic shielding comparable to existing ITO shielding modalities. The combination of high conductivity and shielding along with the materials' earth-abundant nature, and facile large-scale fabrication, make these graphene hybrid films highly attractive for transparent EMI shielding.

  14. Investigations of LRE-HRE-TM thin films for hybrid recording

    Science.gov (United States)

    Li, Zuoyi; Cheng, Xiaomin; Jin, Fang; Li, Zhen; Lin, Gengqi; Yang, Xiaofei

    2005-09-01

    Light rare earth-heavy rare earth-transition metal (LRE-HRE-TM) thin films are a kind of important recording media. A lot of researches have been carried out on the LRE-HRE-TM thin films to improve its properties for data storage application and fruitful results have been achieved. This report gives a glance on the evolution of the research on LRE-HRE-TM recording media. At the same time, combined with the hybrid recording technology, some experimental results obtained on LRE-HRE-TM recording media are discussed, which suggest the promising prospect of the LRE-HRE-TM media in hybrid recording application.

  15. Diamond-like carbon films deposited by a hybrid ECRCVD system

    International Nuclear Information System (INIS)

    Guo, C.T.; Dittrich, K.-H.

    2007-01-01

    A novel hybrid technique for diamond-like carbon (DLC) film deposition has been developed. This technique combines the electron cyclotron resonance chemical vapor deposition (ECRCVD) of C 2 H 2 and metallic magnetron sputtering. Here we described how DLC film is used for a variety of applications such as stamper, PCB micro-tools, and threading form-tools by taking advantage of hybrid ECRCVD system. The structure of the DLC films is delineated by a function of bias voltages by Raman spectroscopy. This function includes parameters such as dependence of G peak positions and the intensity ratio (I D /I G ). Atomic force microscope (AFM) examines the root-mean-square (R.M.S.) roughness and the surface morphology. Excellent adhesion and lower friction coefficients of a DLC film were also assessed

  16. Transparent and flexible conducting hybrid film combined with 3-Aminopropyltriethoxysilane-coated polymer and graphene

    International Nuclear Information System (INIS)

    Jung, Daesung; Ko, Yong-Hun; Cho, Jumi; Adhikari, Prashanta Dhoj; Lee, Su Il; Kim, Yooseok; Song, Wooseok; Jung, Min Wook; Jang, Sung Won; Lee, Seung Youb; An, Ki-Seok; Park, Chong-Yun

    2015-01-01

    A simple approach to fabricate graphene hybrid film consisted of Graphene/3-aminopropyltriethoxysilane (APTES)/polyethylene terephthalate (PET) is presented, using self-assembled monolayers (SAMs) for enhancement of conductivity. The SAMs of APTES was prepared on ultraviolet-ozone (UVO)-irradiated PET films via wet chemical technique. The density of APTES was saturated after UV treatment time of 1 h for PET films; the carrier density and the optical transmittance were 9.3 × 10 12 /cm 2 and 82% for pristine graphene and 1.16 × 10 13 /cm 2 and 86% for graphene hybrid films, respectively, and experienced at inflection point at 30 min in UV treatment time. This behavior can be explained by surface morphology transition due to coalescence or clustering of mobile and low-molecular-weight oxidized components of PET.

  17. Hybrid AC EL structures with thin protective ZnO film

    International Nuclear Information System (INIS)

    Tsvetkova, E; Dikov, H; Kolentsov, K; Yourukova, L; Zhechev, D; Steflekova, V

    2008-01-01

    Alternating current hybrid electroluminescent Al/SnO 2 /ZnS: Cu/ZnO/Al structures with blue emission have been prepared. In these ZnO films are used as protective layers. The optical properties of different RF magnetron sputtered ZnO films have been studied. The voltage - brightness characteristics of AC EL structures with a ZnO protective film and conventional structures with a TiO 2 protective layer are compared. The investigation shows that the brightness of the structures with a ZnO protective film is higher. The improved characteristics of these new hybrid structures could be used in preparing various systems for representation of permanent or variable light information

  18. Hybrid dextran-iron oxide thin films deposited by laser techniques for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Predoi, D.; Ciobanu, C.S. [National Institute for Physics of Materials, P.O. Box MG 07, Bucharest, Magurele (Romania); Radu, M.; Costache, M.; Dinischiotu, A. [Molecular Biology Center, University of Bucharest, 91-95 Splaiul Independentei, 76201, Bucharest 5 (Romania); Popescu, C.; Axente, E.; Mihailescu, I.N. [National Institute for Lasers, Plasma and Radiations Physics, P. O. Box MG 36, 77125 Bucharest (Romania); Gyorgy, E., E-mail: egyorgy@cin2.es [National Institute for Lasers, Plasma and Radiations Physics, P. O. Box MG 36, 77125 Bucharest (Romania); Consejo Superior de Investigaciones Cientificas, Centre d' Investigacions en Nanociencia i Nanotecnologia (CSIC-CIN2), Campus UAB, 08193 Bellaterra (Spain)

    2012-02-01

    Iron oxide nanoparticles were prepared by chemical co-precipitation method. The nanoparticles were mixed with dextran in distilled water. The obtained solutions were frozen in liquid nitrogen and used as targets during matrix assisted pulsed laser evaporation for the growth of hybrid, iron oxide nanoparticles-dextran thin films. Fourier Transform Infrared Spectroscopy and X-ray diffraction investigations revealed that the obtained films preserve the structure and composition of the initial, non-irradiated iron oxide-dextran composite material. The biocompatibility of the iron oxide-dextran thin films was demonstrated by 3-(4.5 dimethylthiazol-2yl)-2.5-diphenyltetrazolium bromide-based colorimetric assay, using human liver hepatocellular carcinoma cells. - Highlights: Black-Right-Pointing-Pointer Hybrid, dextran-iron oxide nanoparticles and thin films. Black-Right-Pointing-Pointer Laser immobilization. Black-Right-Pointing-Pointer Biocompatibility of dextran-iron oxide nanoparticles.

  19. Hybrid dextran-iron oxide thin films deposited by laser techniques for biomedical applications

    International Nuclear Information System (INIS)

    Predoi, D.; Ciobanu, C.S.; Radu, M.; Costache, M.; Dinischiotu, A.; Popescu, C.; Axente, E.; Mihailescu, I.N.; Gyorgy, E.

    2012-01-01

    Iron oxide nanoparticles were prepared by chemical co-precipitation method. The nanoparticles were mixed with dextran in distilled water. The obtained solutions were frozen in liquid nitrogen and used as targets during matrix assisted pulsed laser evaporation for the growth of hybrid, iron oxide nanoparticles-dextran thin films. Fourier Transform Infrared Spectroscopy and X-ray diffraction investigations revealed that the obtained films preserve the structure and composition of the initial, non-irradiated iron oxide-dextran composite material. The biocompatibility of the iron oxide-dextran thin films was demonstrated by 3-(4.5 dimethylthiazol-2yl)-2.5-diphenyltetrazolium bromide-based colorimetric assay, using human liver hepatocellular carcinoma cells. - Highlights: ► Hybrid, dextran-iron oxide nanoparticles and thin films. ► Laser immobilization. ► Biocompatibility of dextran-iron oxide nanoparticles.

  20. Hybrid Perovskite Thin-Film Photovoltaics: In Situ Diagnostics and Importance of the Precursor Solvate Phases

    KAUST Repository

    Munir, Rahim

    2016-11-07

    Solution-processed hybrid perovskite semiconductors attract a great deal of attention, but little is known about their formation process. The one-step spin-coating process of perovskites is investigated in situ, revealing that thin-film formation is mediated by solid-state precursor solvates and their nature. The stability of these intermediate phases directly impacts the quality and reproducibility of thermally converted perovskite films and their photovoltaic performance.

  1. Hybrid Perovskite Thin-Film Photovoltaics: In Situ Diagnostics and Importance of the Precursor Solvate Phases

    KAUST Repository

    Munir, Rahim; Sheikh, Arif D.; Abdelsamie, Maged; Hu, Hanlin; Yu, Liyang; Zhao, Kui; Kim, Taesoo; El Tall, Omar; Li, Ruipeng; Smilgies, Detlef M.; Amassian, Aram

    2016-01-01

    Solution-processed hybrid perovskite semiconductors attract a great deal of attention, but little is known about their formation process. The one-step spin-coating process of perovskites is investigated in situ, revealing that thin-film formation is mediated by solid-state precursor solvates and their nature. The stability of these intermediate phases directly impacts the quality and reproducibility of thermally converted perovskite films and their photovoltaic performance.

  2. Low temperature fabrication of barium titanate hybrid films and their dielectric properties

    International Nuclear Information System (INIS)

    Kobayashi, Yoshio; Saito, Hirobumi; Kinoshita, Takafumi; Nagao, Daisuke; Konno, Mikio

    2011-01-01

    A method for incorporating BT nano-crystalline into barium titanate (BT) films is proposed for a low temperature fabrication of high dielectric constant films. BT nanoparticles were synthesized by hydrolysis of a BT complex alkoxide in 2-methoxyethanol (ME)/ethanol cosolvent. As the ME volume fraction in the cosolvent (ME fraction) increased from 0 to 100%, the particle and crystal sizes tended to increase from 13.4 to 30.2 nm and from 15.8 to 31.4 nm, respectively, and the particle dispersion in the solution became more improved. The BT particles were mixed with BT complex alkoxide dissolved in an ME/ethanol cosolvent for preparing a precursor solution that was then spin-coated on a Pt substrate and dried at 150 o C. The dielectric constant of the spin-coated BT hybrid film increased with an increase in the volume fraction of the BT particles in the film. The dissipation factor of the hybrid film tended to decrease with an increase in the ME fraction in the precursor solution. The hybrid film fabricated at a BT fraction of 30% and an ME fraction of 25% attained a dielectric constant as high as 94.5 with a surface roughness of 14.0 nm and a dissipation factor of 0.11.

  3. Preparation and characterization of ultra-thin amphiphobic coatings on silicon wafers

    International Nuclear Information System (INIS)

    Mou, Chun-Yueh; Yuan, Wei-Li; Shih, Chih-Hsin

    2013-01-01

    Fluorine-based amphiphobic coatings have been widely used in commercial domestic utensils and textiles to repel water and oil contaminants. However, few reports from the literature survey have discussed the effects on amphiphobicity of the nano- to micro-scale surface features of such a coating. In this research thin amphiphobic epoxy coatings based on a mixture of bisphenol A diglycidyl ether, tetraethylorthosilicate (TEOS), and a particular alkoxy silane with fluorinated side chains (F-silane) are deposited on silicon wafers. Film amphiphobicity is characterized by the measurement of water and oil contact angles of the coating. Film morphology is revealed in the scanned images using atomic force microscopy. The deposited films free of F-silane are about 10 nm thick. When a small amount of F-silane was firstly added, the water and oil contact angles of the deposited films jumped up to 107° and 69° respectively and then flattened out with increased F-silane. Water droplets gave an average plateau contact angle about 110°, while vegetable oil ones, 40°. It was noted that there is a dramatic decrease in the lyophobicity causing a reduction in contact angles. However, surface lyophobicity also depends on sub-microscopic surface structures. In addition, by increasing TEOS, it was shown that the formed silica sols or granules were helpful in enhancing the mechanical strength along with retaining the lyophobicity of the film. - Highlights: • Epoxy ultrathin films about 10 nm thick deposited on silicon wafer. • Nominal fluorinated silane added to epoxy coatings for amphiphobicity. • Surface lyophobicity retained by sub-micrometer granules in ultrathin coatings. • Film hardness improved by adding tetraethylorthosilicate

  4. Preparation and characterization of ultra-thin amphiphobic coatings on silicon wafers

    Energy Technology Data Exchange (ETDEWEB)

    Mou, Chun-Yueh, E-mail: cymou165@gmail.com; Yuan, Wei-Li; Shih, Chih-Hsin

    2013-06-30

    Fluorine-based amphiphobic coatings have been widely used in commercial domestic utensils and textiles to repel water and oil contaminants. However, few reports from the literature survey have discussed the effects on amphiphobicity of the nano- to micro-scale surface features of such a coating. In this research thin amphiphobic epoxy coatings based on a mixture of bisphenol A diglycidyl ether, tetraethylorthosilicate (TEOS), and a particular alkoxy silane with fluorinated side chains (F-silane) are deposited on silicon wafers. Film amphiphobicity is characterized by the measurement of water and oil contact angles of the coating. Film morphology is revealed in the scanned images using atomic force microscopy. The deposited films free of F-silane are about 10 nm thick. When a small amount of F-silane was firstly added, the water and oil contact angles of the deposited films jumped up to 107° and 69° respectively and then flattened out with increased F-silane. Water droplets gave an average plateau contact angle about 110°, while vegetable oil ones, 40°. It was noted that there is a dramatic decrease in the lyophobicity causing a reduction in contact angles. However, surface lyophobicity also depends on sub-microscopic surface structures. In addition, by increasing TEOS, it was shown that the formed silica sols or granules were helpful in enhancing the mechanical strength along with retaining the lyophobicity of the film. - Highlights: • Epoxy ultrathin films about 10 nm thick deposited on silicon wafer. • Nominal fluorinated silane added to epoxy coatings for amphiphobicity. • Surface lyophobicity retained by sub-micrometer granules in ultrathin coatings. • Film hardness improved by adding tetraethylorthosilicate.

  5. Voltage control of a magnetization easy axis in piezoelectric/ferromagnetic hybrid films

    International Nuclear Information System (INIS)

    Kim, Sang-Koog; Lee, Jeong-Won; Shin, Sung-Chul; Song, Han Wook; Lee, Chang Ho; No, Kwangsoo

    2003-01-01

    We have established a spontaneous magnetization-axis switching in ferromagnetic films by applying a low voltage to a piezoelectric layer in a newly developed hybrid system comprised of the ferromagnetic and piezoelectric films. The magnetization easy axis along which a spontaneous magnetization is oriented, is readily switchable by a voltage without applying an external magnetic field through both the inverse magnetostrictive and piezoelectric effects of CoPd and lead-zirconate-titanate alloy films, respectively. This challenging work provides a new way into the memory writing as well as storage means of ultrahigh bit densities in nonvolatile magnetic random access memory

  6. Hybrid methyl green/cobalt-polyoxotungstate nanostructured films: Self-assembly, electrochemical and electrocatalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Novais, Hugo C.; Fernandes, Diana M., E-mail: diana.fernandes@fc.up.pt; Freire, Cristina, E-mail: acfreire@fc.up.pt

    2015-08-30

    Graphical abstract: Hybrid {MG/Co(PW9)2}{sub n} multilayer films were successfully prepared and exhibit W-based electrocatalytic activity towards reduction of nitrite and iodate anions. - Highlights: • Layer-by-layer hybrid films {MG/Co(PW_9)_2}{sub n} were sucessfully prepared. • UV–vis was used to monitor film build-up and showed regular stepwise film growth. • XPS confirmed sucessfull {MG/Co(PW_9)_2}{sub n} film fabrication. • Films showed excellent electrocatalytic activity towards nitrite and iodate reduction. - Abstract: Hybrid multilayer films were prepared by alternately depositing cationic dye methyl green (MG) and anionic sandwich-type polyoxometalate K{sub 10}[Co{sub 4}(H{sub 2}O){sub 2}(PW{sub 9}O{sub 34}){sub 2}] (Co(PW{sub 9}){sub 2}) via electrostatic layer-by-layer (LbL) self-assembly method. Film build-up was monitored by UV–vis spectroscopy which showed a regular stepwise growth. X-ray photoelectron spectroscopy data confirmed the successful fabrication of the hybrid films with MG-Co(PW{sub 9}){sub 2} composition and scanning electron microscopy images revealed a completely covered surface with a non-uniform distribution of the molecular species. Electrochemical characterization of films by cyclic voltammetry revealed two tungsten-based reduction processes in the potential range between −0.9 and −0.5 V due to W{sup VI} → W{sup V} in Co(PW{sub 9}){sub 2}. Studies with the redox probes, [Fe(CN){sub 6}]{sup 3−/4−} and [Ru(NH{sub 3}){sub 6}]{sup 3+/2+}, revealed that not only the electrostatic attractions or repulsions have effects on the kinetics of the probe reactions, but also the film thickness. Additionally, the {MG/Co(PW_9)_2}{sub n} multilayer films exhibit efficient W-based electrocatalytic activity towards reduction of nitrite and iodate.

  7. MgB2 ultrathin films fabricated by hybrid physical chemical vapor deposition and ion milling

    Directory of Open Access Journals (Sweden)

    Narendra Acharya

    2016-08-01

    Full Text Available In this letter, we report on the structural and transport measurements of ultrathin MgB2 films grown by hybrid physical-chemical vapor deposition followed by low incident angle Ar ion milling. The ultrathin films as thin as 1.8 nm, or 6 unit cells, exhibit excellent superconducting properties such as high critical temperature (Tc and high critical current density (Jc. The results show the great potential of these ultrathin films for superconducting devices and present a possibility to explore superconductivity in MgB2 at the 2D limit.

  8. Preparation and characterization of B-C-N hybrid thin films

    International Nuclear Information System (INIS)

    Uddin, Md. Nizam; Shimoyama, Iwao; Sekiguchi, Tetsuhiro; Baba, Yuji; Nath, Krishna G.; Nagano, Masamitsu

    2006-06-01

    Two dimensional thin films composed of boron, carbon and nitrogen (B-C-N hybrid) were synthesized by ion beam deposition, and their electronic and geometrical structures were characterized by core-level spectroscopy using synchrotron radiation. B-C-N hybrid thin films were grown from ion beam plasma of borazine on highly oriented pyrolitic graphite (HOPG) at various temperatures. The films were characterized in-situ by X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS). XPS study suggested that B, N and C atoms in the deposited films were in a wide variety of chemical bonds e.g., B-C, B-N, N-C, and B-C-N. It was found that B-C-N hybrid formation was enhanced at high temperature, and that the B-C-N component was dominantly synthesized at low boron content. In the NEXAFS spectra, the resonance peaks from B 1s to unoccupied π * -like orbitals were clearly observed. The polarization dependence of the B 1s → π * resonance peaks confirmed that the highly oriented graphite-like B-C-N hybrids surely exist at low boron content. (author)

  9. Voltammetry of osmium-modified DNA at a mercury film electrode application in detecting DNA hybridization

    Czech Academy of Sciences Publication Activity Database

    Kostečka, Pavel; Havran, Luděk; Pivoňková, Hana; Fojta, Miroslav

    2004-01-01

    Roč. 63, 1-2 (2004), s. 245-248 ISSN 1567-5394 R&D Projects: GA AV ČR IAA4004108; GA AV ČR KJB4004302 Institutional research plan: CEZ:AV0Z5004920 Keywords : osmium * DNA hybridization * mercury film electrode Subject RIV: BO - Biophysics Impact factor: 2.261, year: 2004

  10. III-V Ultra-Thin-Body InGaAs/InAs MOSFETs for Low Standby Power Logic Applications

    Science.gov (United States)

    Huang, Cheng-Ying

    As device scaling continues to sub-10-nm regime, III-V InGaAs/InAs metal- oxide-semiconductor ?eld-e?ect transistors (MOSFETs) are promising candidates for replacing Si-based MOSFETs for future very-large-scale integration (VLSI) logic applications. III-V InGaAs materials have low electron effective mass and high electron velocity, allowing higher on-state current at lower VDD and reducing the switching power consumption. However, III-V InGaAs materials have a narrower band gap and higher permittivity, leading to large band-to-band tunneling (BTBT) leakage or gate-induced drain leakage (GIDL) at the drain end of the channel, and large subthreshold leakage due to worse electrostatic integrity. To utilize III-V MOSFETs in future logic circuits, III-V MOSFETs must have high on-state performance over Si MOSFETs as well as very low leakage current and low standby power consumption. In this dissertation, we will report InGaAs/InAs ultra-thin-body MOSFETs. Three techniques for reducing the leakage currents in InGaAs/InAs MOSFETs are reported as described below. 1) Wide band-gap barriers: We developed AlAs0.44Sb0.56 barriers lattice-match to InP by molecular beam epitaxy (MBE), and studied the electron transport in In0.53Ga0.47As/AlAs 0.44Sb0.56 heterostructures. The InGaAs channel MOSFETs using AlAs0.44Sb0.56 bottom barriers or p-doped In0.52 Al0.48As barriers were demonstrated, showing significant suppression on the back barrier leakage. 2) Ultra-thin channels: We investigated the electron transport in InGaAs and InAs ultra-thin quantum wells and ultra-thin body MOSFETs (t ch ~ 2-4 nm). For high performance logic, InAs channels enable higher on-state current, while for low power logic, InGaAs channels allow lower BTBT leakage current. 3) Source/Drain engineering: We developed raised InGaAs and recessed InP source/drain spacers. The raised InGaAs source/drain spacers improve electrostatics, reducing subthreshold leakage, and smooth the electric field near drain, reducing

  11. Efficient photovoltaic conversion of graphene–carbon nanotube hybrid films grown from solid precursors

    International Nuclear Information System (INIS)

    Gan, Xin; Lv, Ruitao; Bai, Junfei; Zhang, Zexia; Wei, Jinquan; Huang, Zheng-Hong; Zhu, Hongwei; Kang, Feiyu; Terrones, Mauricio

    2015-01-01

    Large-area (e.g. centimeter size) graphene sheets are usually synthesized via pyrolysis of gaseous carbon precursors (e.g. methane) on metal substrates like Cu using chemical vapor deposition (CVD), but the presence of grain boundaries and the residual polymers during transfer deteriorates significantly the properties of the CVD graphene. If carbon nanotubes (CNTs) can be covalently bonded to graphene, the hybrid system could possess excellent electrical conductivity, transparency and mechanical strength. In this work, conducting and transparent CNT–graphene hybrid films were synthesized by a facile solid precursor pyrolysis method. Furthermore, the synthesized CNT–graphene hybrid films display enhanced photovoltaic conversion efficiency when compared to devices based on CNT membranes or graphene sheets. Upon chemical doping, the graphene–CNT/Si solar cells reveal power conversion efficiencies up to 8.50%. (paper)

  12. Photothermally Activated Pyroelectric Polymer Films for Harvesting of Solar Heat with a Hybrid Energy Cell Structure.

    Science.gov (United States)

    Park, Teahoon; Na, Jongbeom; Kim, Byeonggwan; Kim, Younghoon; Shin, Haijin; Kim, Eunkyoung

    2015-12-22

    Photothermal effects in poly(3,4-ethylenedioxythiophene)s (PEDOTs) were explored for pyroelectric conversion. A poled ferroelectric film was coated on both sides with PEDOT via solution casting polymerization of EDOT, to give highly conductive and effective photothermal thin films of PEDOT. The PEDOT films not only provided heat source upon light exposure but worked as electrodes for the output energy from the pyroelectric layer in an energy harvester hybridized with a thermoelectric layer. Compared to a bare thermoelectric system under NIR irradiation, the photothermal-pyro-thermoelectric device showed more than 6 times higher thermoelectric output with the additional pyroelectric output. The photothermally driven pyroelectric harvesting film provided a very fast electric output with a high voltage output (Vout) of 15 V. The pyroelectric effect was significant due to the transparent and high photothermal PEDOT film, which could also work as an electrode. A hybrid energy harvester was assembled to enhance photoconversion efficiency (PCE) of a solar cell with a thermoelectric device operated by the photothermally generated heat. The PCE was increased more than 20% under sunlight irradiation (AM 1.5G) utilizing the transmitted light through the photovoltaic cell as a heat source that was converted into pyroelectric and thermoelectric output simultaneously from the high photothermal PEDOT electrodes. Overall, this work provides a dynamic and static hybrid energy cell to harvest solar energy in full spectral range and thermal energy, to allow solar powered switching of an electrochromic display.

  13. Carbon nanotube-TiO(2) hybrid films for detecting traces of O(2).

    Science.gov (United States)

    Llobet, E; Espinosa, E H; Sotter, E; Ionescu, R; Vilanova, X; Torres, J; Felten, A; Pireaux, J J; Ke, X; Van Tendeloo, G; Renaux, F; Paint, Y; Hecq, M; Bittencourt, C

    2008-09-17

    Hybrid titania films have been prepared using an adapted sol-gel method for obtaining well-dispersed hydrogen plasma-treated multiwall carbon nanotubes in either pure titania or Nb-doped titania. The drop-coating method has been used to fabricate resistive oxygen sensors based on titania or on titania and carbon nanotube hybrids. Morphology and composition studies have revealed that the dispersion of low amounts of carbon nanotubes within the titania matrix does not significantly alter its crystallization behaviour. The gas sensitivity studies performed on the different samples have shown that the hybrid layers based on titania and carbon nanotubes possess an unprecedented responsiveness towards oxygen (i.e. more than four times higher than that shown by optimized Nb-doped TiO(2) films). Furthermore, hybrid sensors containing carbon nanotubes respond at significantly lower operating temperatures than their non-hybrid counterparts. These new hybrid sensors show a strong potential for monitoring traces of oxygen (i.e. ≤10 ppm) in a flow of CO(2), which is of interest for the beverage industry.

  14. Carbon nanotube-TiO2 hybrid films for detecting traces of O2

    International Nuclear Information System (INIS)

    Llobet, E; Espinosa, E H; Sotter, E; Ionescu, R; Vilanova, X; Torres, J; Felten, A; Pireaux, J J; Ke, X; Tendeloo, G Van; Renaux, F; Paint, Y; Hecq, M; Bittencourt, C

    2008-01-01

    Hybrid titania films have been prepared using an adapted sol-gel method for obtaining well-dispersed hydrogen plasma-treated multiwall carbon nanotubes in either pure titania or Nb-doped titania. The drop-coating method has been used to fabricate resistive oxygen sensors based on titania or on titania and carbon nanotube hybrids. Morphology and composition studies have revealed that the dispersion of low amounts of carbon nanotubes within the titania matrix does not significantly alter its crystallization behaviour. The gas sensitivity studies performed on the different samples have shown that the hybrid layers based on titania and carbon nanotubes possess an unprecedented responsiveness towards oxygen (i.e. more than four times higher than that shown by optimized Nb-doped TiO 2 films). Furthermore, hybrid sensors containing carbon nanotubes respond at significantly lower operating temperatures than their non-hybrid counterparts. These new hybrid sensors show a strong potential for monitoring traces of oxygen (i.e. ≤10 ppm) in a flow of CO 2 , which is of interest for the beverage industry

  15. Carbon nanotube TiO2 hybrid films for detecting traces of O2

    Science.gov (United States)

    Llobet, E.; Espinosa, E. H.; Sotter, E.; Ionescu, R.; Vilanova, X.; Torres, J.; Felten, A.; Pireaux, J. J.; Ke, X.; Van Tendeloo, G.; Renaux, F.; Paint, Y.; Hecq, M.; Bittencourt, C.

    2008-09-01

    Hybrid titania films have been prepared using an adapted sol-gel method for obtaining well-dispersed hydrogen plasma-treated multiwall carbon nanotubes in either pure titania or Nb-doped titania. The drop-coating method has been used to fabricate resistive oxygen sensors based on titania or on titania and carbon nanotube hybrids. Morphology and composition studies have revealed that the dispersion of low amounts of carbon nanotubes within the titania matrix does not significantly alter its crystallization behaviour. The gas sensitivity studies performed on the different samples have shown that the hybrid layers based on titania and carbon nanotubes possess an unprecedented responsiveness towards oxygen (i.e. more than four times higher than that shown by optimized Nb-doped TiO2 films). Furthermore, hybrid sensors containing carbon nanotubes respond at significantly lower operating temperatures than their non-hybrid counterparts. These new hybrid sensors show a strong potential for monitoring traces of oxygen (i.e. beverage industry.

  16. Diode behavior in ultra-thin low temperature ALD grown zinc-oxide on silicon

    Directory of Open Access Journals (Sweden)

    Nazek El-Atab

    2013-10-01

    Full Text Available A thin-film ZnO(n/Si(p+ heterojunction diode is demonstrated. The thin film ZnO layer is deposited by Atomic Layer Deposition (ALD at different temperatures on a p-type silicon substrate. Atomic force microscopy (AFM AC-in-Air method in addition to conductive AFM (CAFM were used for the characterization of ZnO layer and to measure the current-voltage characteristics. Forward and reverse bias n-p diode behavior with good rectification properties is achieved. The diode with ZnO grown at 80°C exhibited the highest on/off ratio with a turn-on voltage (VON ∼3.5 V. The measured breakdown voltage (VBR and electric field (EBR for this diode are 5.4 V and 3.86 MV/cm, respectively.

  17. High-resolution structural studies of ultra-thin magnetic, transition metal overlayers and two-dimensional transition metal oxides using synchrotron radiation

    International Nuclear Information System (INIS)

    Kellar, S.A.; Lawrence Berkeley National Lab., CA

    1997-05-01

    This thesis report the surface-structure determination of three, ultra-thin magnetic transition-metal films, Fe/Au(100), Mn/Ni(100), and Mn/Cu(100) using Angle-Resolved Photoemission Extended Fine Structure (ARPEFS) and photoelectron holography. These structural studies are the first to use non-s initial states in the ARPEFS procedure. This thesis also reports an ARPEFS surface-structure determination of a two-dimensional transition-metal oxide, [(1 x 1)O/W(110)] x 12. The authors have analyzed the ARPFES signal from the Au 4f 7/5 core level of the Au(1 ML)/Fe(15 ML)/Au(100) system. The analysis shows that the Fe grows layer by layer with one monolayer of gold, acting as a surfactant, remaining on top of the growing Fe layers. These surface gold atoms sit in the four-fold hollow site, 1.67 ± 0.02 A above the iron surface. The grown Fe layer is very much like the bulk, bcc iron, with an interlayer spacing of 1.43 ± 0.03 A. Analysis of the Mn 3p ARPEFS signals from c(2 x 2)Mn/Ni(100) and c(2 x 2)Mn/Cu(100) shows that the Mn forms highly corrugated surface alloys. The corrugation of the Mn/Ni(100) and Mn/Cu(100) systems are 0.24 ± 0.02 A and 0.30 ± 0.04 A respectively. In both cases the Mn is sticking above the plane of the surface substrate atoms. For the Mn/Ni(100) system the first layer Ni is contracted 4% from the bulk value. The Mn/Cu(100) system shows bulk spacing for the substrate Cu. Photoelectron holography shows that the Mn/Ni interface is very abrupt with very little Mn leaking into the second layer, while the Mn/Cu(100) case has a significant amount of Mn leaking into the second layer. A new, five-element electrostatic electron lens was developed for hemispherical electron-energy analyzers. This lens system can be operated at constant transverse or constants angular magnification, and has been optimized for use with the very small photon-spot sizes. Improvements to the hemispherical electron-energy analyzer are also discussed

  18. High-resolution structural studies of ultra-thin magnetic, transition metal overlayers and two-dimensional transition metal oxides using synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Kellar, S.A. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry]|[Lawrence Berkeley National Lab., CA (United States). Advanced Light Source Div.

    1997-05-01

    This thesis report the surface-structure determination of three, ultra-thin magnetic transition-metal films, Fe/Au(100), Mn/Ni(100), and Mn/Cu(100) using Angle-Resolved Photoemission Extended Fine Structure (ARPEFS) and photoelectron holography. These structural studies are the first to use non-s initial states in the ARPEFS procedure. This thesis also reports an ARPEFS surface-structure determination of a two-dimensional transition-metal oxide, [(1 x 1)O/W(110)] x 12. The authors have analyzed the ARPFES signal from the Au 4f{sub 7/5} core level of the Au(1 ML)/Fe(15 ML)/Au(100) system. The analysis shows that the Fe grows layer by layer with one monolayer of gold, acting as a surfactant, remaining on top of the growing Fe layers. These surface gold atoms sit in the four-fold hollow site, 1.67 {+-} 0.02 A above the iron surface. The grown Fe layer is very much like the bulk, bcc iron, with an interlayer spacing of 1.43 {+-} 0.03 A. Analysis of the Mn 3p ARPEFS signals from c(2 x 2)Mn/Ni(100) and c(2 x 2)Mn/Cu(100) shows that the Mn forms highly corrugated surface alloys. The corrugation of the Mn/Ni(100) and Mn/Cu(100) systems are 0.24 {+-} 0.02 A and 0.30 {+-} 0.04 A respectively. In both cases the Mn is sticking above the plane of the surface substrate atoms. For the Mn/Ni(100) system the first layer Ni is contracted 4% from the bulk value. The Mn/Cu(100) system shows bulk spacing for the substrate Cu. Photoelectron holography shows that the Mn/Ni interface is very abrupt with very little Mn leaking into the second layer, while the Mn/Cu(100) case has a significant amount of Mn leaking into the second layer. A new, five-element electrostatic electron lens was developed for hemispherical electron-energy analyzers. This lens system can be operated at constant transverse or constants angular magnification, and has been optimized for use with the very small photon-spot sizes. Improvements to the hemispherical electron-energy analyzer are also discussed.

  19. Preparation of ultra-thin polypyrrole nanosheets decorated with Ag nanoparticles and their application in hydrogen peroxide detection

    International Nuclear Information System (INIS)

    Mahmoudian, M.R.; Alias, Y.; Basirun, W.J.; Ebadi, M.

    2012-01-01

    Highlights: ► Ag nanoparticles-decorated ultra thin polypyrrole nanosheets were prepared. ► Higher surface area of the polymer increased interaction between the polymer and Ag + . ► The sensitivity was estimated to be 4.477 μA mM −1 for linear segment. ► The LOD and LOQ (S/N = 3) were estimated to be 0.57 μM and 1.93 μM, respectively. - Abstract: This study examines the preparation of ultra-thin polypyrrole nanosheets decorated with Ag nanoparticles (Ag-UTPNSs) and their application in the enzyme-less detection of hydrogen peroxide (H 2 O 2 ) detection. The X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) results confirmed that Ag nanoparticles (NPs) were deposited onto the surface of the UTPNSs. The increase of the H 2 O 2 reduction current peak to 120 μA in the presence of the Ag-UTPNS/glassy carbon electrode (GCE) as compared to the UTPNS/GCE indicates that the sensitivity of the electrode to H 2 O 2 is significant. This observation can be explained by the larger surface area of the UTPNSs, which can increase the interactions between the polymer and the AgNO 3 solution during the deposition of the Ag NPs, and by the small size of the deposited Ag NPs, which can produce a surface area of Ag that is suitable for the reaction with H 2 O 2 . The amperometric responses show that the limit of detection, the limit of quantification (S/N = 3) and the sensitivity are estimated to be 0.57 μM, 1.93 μM and 4.477 μA mM −1 , respectively, for the linear segment. The results of the reproducibility experiments show that the use of Ag-UTPNS/GCE is feasible for the quantitative detection of certain concentration ranges of H 2 O 2 .

  20. Self-regulated growth of LaVO3 thin films by hybrid molecular beam epitaxy

    International Nuclear Information System (INIS)

    Zhang, Hai-Tian; Engel-Herbert, Roman; Dedon, Liv R.; Martin, Lane W.

    2015-01-01

    LaVO 3 thin films were grown on SrTiO 3 (001) by hybrid molecular beam epitaxy. A volatile metalorganic precursor, vanadium oxytriisopropoxide (VTIP), and elemental La were co-supplied in the presence of a molecular oxygen flux. By keeping the La flux fixed and varying the VTIP flux, stoichiometric LaVO 3 films were obtained for a range of cation flux ratios, indicating the presence of a self-regulated growth window. Films grown under stoichiometric conditions were found to have the largest lattice parameter, which decreased monotonically with increasing amounts of excess La or V. Energy dispersive X-ray spectroscopy and Rutherford backscattering measurements were carried out to confirm film compositions. Stoichiometric growth of complex vanadate thin films independent of cation flux ratios expands upon the previously reported self-regulated growth of perovskite titanates using hybrid molecular beam epitaxy, thus demonstrating the general applicability of this growth approach to other complex oxide materials, where a precise control over film stoichiometry is demanded by the application

  1. Organic thin film transistor integration: a hybrid approach

    National Research Council Canada - National Science Library

    Li, F. M

    2011-01-01

    .... Her research interests are in the field of nanoand thin-film technology for applications in large area and flexible electronics, including displays, sensors, photovoltaics, circuits and systems. Dr. Li has co-authored a book entitled CCD Image Sensors in Deep-Ultraviolet (2005), and has published articles in various scientific journals. Arokia Nathan holds the...

  2. Structure and morphology of magnetron sputter deposited ultrathin ZnO films on confined polymeric template

    Science.gov (United States)

    Singh, Ajaib; Schipmann, Susanne; Mathur, Aakash; Pal, Dipayan; Sengupta, Amartya; Klemradt, Uwe; Chattopadhyay, Sudeshna

    2017-08-01

    The structure and morphology of ultra-thin zinc oxide (ZnO) films with different film thicknesses on confined polymer template were studied through X-ray reflectivity (XRR) and grazing incidence small angle X-ray scattering (GISAXS). Using magnetron sputter deposition technique ZnO thin films with different film thicknesses (weight of polystyrene). The detailed internal structure, along the surface/interfaces and the growth direction of the system were explored in this study, which provides insight into the growth procedure of ZnO on confined polymer and reveals that a thin layer of ZnO, with very low surface and interface roughness, can be grown by DC magnetron sputtering technique, with approximately full coverage (with bulk like electron density) even in nm order of thickness, in 2-7 nm range on confined polymer template, without disturbing the structure of the underneath template. The resulting ZnO-polystyrene hybrid systems show strong ZnO near band edge (NBE) and deep-level (DLE) emissions in their room temperature photoluminescence spectra, where the contribution of DLE gets relatively stronger with decreasing ZnO film thickness, indicating a significant enhancement of surface defects because of the greater surface to volume ratio in thinner films.

  3. Orbital hybridization, crystal structure and anomalous resistivity of ultrathin CrZrx alloy films on polymeric substrates

    International Nuclear Information System (INIS)

    Evans, Drew; Zuber, Kamil; Merkens, Kerstin; Murphy, Peter

    2012-01-01

    The orbital hybridization and crystal structure are experimentally explored for ultrathin chrome zirconium (CrZr x ) alloy films co-sputtered on precoated polymeric substrates. We determine the level of orbital hybridization and crystal structure using X-ray photoelectron spectroscopy and electron diffraction. Body-centred cubic and Ω-hexagonally close-packed phases are observed to coexist in the sputtered Cr-based films. Experiments reveal the orbital hybridization and crystal structure combine to produce anomalous resistivity for these ultrathin films.

  4. High Refractive Organic–Inorganic Hybrid Films Prepared by Low Water Sol-Gel and UV-Irradiation Processes

    Directory of Open Access Journals (Sweden)

    Hsiao-Yuan Ma

    2016-03-01

    Full Text Available Organic-inorganic hybrid sols (Ti–O–Si precursor were first synthesized by the sol-gel method at low addition of water, and were then employed to prepare a highly refractive hybrid optical film. This film was obtained by blending the Ti–O–Si precursor with 2-phenylphenoxyethyl acrylate (OPPEA to perform photo-polymerization by ultraviolet (UV irradiation. Results show that the film transparency of poly(Ti–O–Si precursor-co-OPPEA film is higher than that of a pure poly(Ti–O–Si precursor film, and that this poly(Ti–O–Si precursor-co-OPPEA hybrid film exhibits a high transparency of ~93.7% coupled with a high refractive index (n of 1.83 corresponding to a thickness of 2.59 μm.

  5. Nacre-like hybrid films: Structure, properties, and the effect of relative humidity.

    Science.gov (United States)

    Abba, Mohammed T; Hunger, Philipp M; Kalidindi, Surya R; Wegst, Ulrike G K

    2015-03-01

    Functional materials often are hybrids composed of biopolymers and mineral constituents. The arrangement and interactions of the constituents frequently lead to hierarchical structures with exceptional mechanical properties and multifunctionality. In this study, hybrid thin films with a nacre-like brick-and-mortar microstructure were fabricated in a straightforward and reproducible manner through manual shear casting using the biopolymer chitosan as the matrix material (mortar) and alumina platelets as the reinforcing particles (bricks). The ratio of inorganic to organic content was varied from 0% to 15% and the relative humidities from 36% to 75% to determine their effects on the mechanical properties. It was found that increasing the volume fraction of alumina from 0% to 15% results in a twofold increase in the modulus of the film, but decreases the tensile strength by up to 30%, when the volume fraction of alumina is higher than 5%. Additionally, this study quantifies and illustrates the critical role of the relative humidity on the mechanical properties of the hybrid film. Increasing the relative humidity from 36% to 75% decreases the modulus and strength by about 45% and triples the strain at failure. These results suggest that complex hybrid materials can be manufactured and tailor made for specific applications or environmental conditions. Copyright © 2015. Published by Elsevier Ltd.

  6. Development and characterization of ultra-thin dosemeters of aluminium oxide

    International Nuclear Information System (INIS)

    Villagran V, E.

    2003-01-01

    The aim of the present thesis work has been to investigate the thermoluminescent (Tl) response of aluminium oxide thin films with thicknesses of the order of 300 nm prepared by laser ablation. Aluminium oxide thin films show Tl response after they are subject to ultraviolet, beta and gamma radiation. The Tl curves exhibit peaks around 75 C and 169 C for UV radiation, 112 C and 180 C for beta particles and 110 C and 176 C for gamma radiation. In order to improve the Tl response some growth parameters such as power density and distance target-substrate were varied. The relation dose-response shows a non-linear behavior for UV irradiation; a linear behavior for beta-particles dose from 150 mGy to 50 Gy, and a linear behavior for gamma radiation dose from 5 Gy to 100 Gy. The kinetic Tl parameters were determined by Computerized Glow Curve Deconvolution (CGCD) method as well as using analytical methods. The CGCD results show that the high temperature peak is composed by four peaks with maximums in 165.7, 188.1, 215.3, 246.5 C. These obey a second order kinetics. The trap depth (E) values are 1.4, 1.6, 1.8 and 2.0 eV respectively. The different analytical results show a trap depth values of 0.914, 0.82 and 0.656 eV respectively. Oxide aluminium thin films obtained would be a suitable tool owing to their potential applications in clinical dosimetry, in the dose distributions due to weekly penetrating radiation determination, and in interfaces dosimetry. (Author)

  7. Structure and morphology of magnetron sputter deposited ultrathin ZnO films on confined polymeric template

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Ajaib [Discipline of Metallurgy Engineering and Materials Science, Indian Institute of Technology Indore, Indore 453552 (India); Schipmann, Susanne [II. Insatitute of Physics and JARA-FIT, RWTH Aachen University, 52056 Aachen (Germany); Mathur, Aakash; Pal, Dipayan [Discipline of Metallurgy Engineering and Materials Science, Indian Institute of Technology Indore, Indore 453552 (India); Sengupta, Amartya [Department of Physics, Indian Institute of Technology Delhi, Delhi 110016 (India); Klemradt, Uwe [II. Insatitute of Physics and JARA-FIT, RWTH Aachen University, 52056 Aachen (Germany); Chattopadhyay, Sudeshna, E-mail: sudeshna@iiti.ac.in [Discipline of Metallurgy Engineering and Materials Science, Indian Institute of Technology Indore, Indore 453552 (India); Discipline of Physics, Indian Institute of Technology Indore, Indore 453552 (India); Centre for Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Indore 453552 (India)

    2017-08-31

    Highlights: • Ultra-thin ZnO films grown on confined polymeric (polystyrene, PS) template. • XRR and GISAXS explore the surface/interfaces structure and morphology of ZnO/PS. • Insights into the growth mechanism of magnetron sputtered ZnO thin film on PS template. • Nucleated disk-like cylindrical particles are the basis of the formation of ZnO layers. • Effect of ZnO film thickness on room temperature PL spectra in ZnO/PS systems. - Abstract: The structure and morphology of ultra-thin zinc oxide (ZnO) films with different film thicknesses on confined polymer template were studied through X-ray reflectivity (XRR) and grazing incidence small angle X-ray scattering (GISAXS). Using magnetron sputter deposition technique ZnO thin films with different film thicknesses (<10 nm) were grown on confined polystyrene with ∼2R{sub g} film thickness, where R{sub g} ∼ 20 nm (R{sub g} is the unperturbed radius of gyration of polystyrene, defined by R{sub g} = 0.272 √M{sub 0}, and M{sub 0} is the molecular weight of polystyrene). The detailed internal structure, along the surface/interfaces and the growth direction of the system were explored in this study, which provides insight into the growth procedure of ZnO on confined polymer and reveals that a thin layer of ZnO, with very low surface and interface roughness, can be grown by DC magnetron sputtering technique, with approximately full coverage (with bulk like electron density) even in nm order of thickness, in 2–7 nm range on confined polymer template, without disturbing the structure of the underneath template. The resulting ZnO-polystyrene hybrid systems show strong ZnO near band edge (NBE) and deep-level (DLE) emissions in their room temperature photoluminescence spectra, where the contribution of DLE gets relatively stronger with decreasing ZnO film thickness, indicating a significant enhancement of surface defects because of the greater surface to volume ratio in thinner films.

  8. Tuning Structure and Properties of Graded Triblock Terpolymer-Based Mesoporous and Hybrid Films

    KAUST Repository

    Phillip, William A.

    2011-07-13

    Despite considerable efforts toward fabricating ordered, water-permeable, mesoporous films from block copolymers, fine control over pore dimensions, structural characteristics, and mechanical behavior of graded structures remains a major challenge. To this end, we describe the fabrication and performance characteristics of graded mesoporous and hybrid films derived from the newly synthesized triblock terpolymer, poly(isoprene-b-styrene-b-4-vinylpyridine). A unique morphology, unachievable in diblock copolymer systems, with enhanced mechanical integrity is evidenced. The film structure comprises a thin selective layer containing vertically aligned and nearly monodisperse mesopores at a density of more than 1014 per m2 above a graded macroporous layer. Hybridization via homopolymer blending enables tuning of pore size within the range of 16 to 30 nm. Solvent flow and solute separation experiments demonstrate that the terpolymer films have permeabilities comparable to commercial membranes, are stimuli-responsive, and contain pores with a nearly monodisperse diameter. These results suggest that moving to multiblock polymers and their hybrids may open new paths to produce high-performance graded membranes for filtration, separations, nanofluidics, catalysis, and drug delivery. © 2011 American Chemical Society.

  9. Hybrid manganese oxide films for supercapacitor application prepared by sol-gel technique

    International Nuclear Information System (INIS)

    Chen, Chin-Yi; Wang, Sheng-Chang; Tien, Yue-Han; Tsai, Wen-Ta; Lin, Chung-Kwei

    2009-01-01

    Hybrid films were prepared by adding various concentrations of meso-carbon microbeads (MCMB) during sol-gel processing of manganese oxide films. The heat-treated films were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). In addition, electrochemical performance of the MCMB-added Mn-oxide hybrid coatings was evaluated by cyclic voltammetry (CV) and compared with its unadded counterpart. Experimental results showed that Mn-oxide films exhibited a mixture of Mn 2 O 3 and Mn 3 O 4 phases. The higher the heat-treatment temperature, the more Mn 2 O 3 can be observed. The specific capacitance of the unadded Mn-oxide electrodes is 209 F/g. Because the MCMB particles provide more interfacial surface area for electrochemical reactions, a significant improvement can be noticed by adding MCMB in Mn-oxide coatings. The 300 o C heat-treated hybrid Mn-oxide coating with a Mn/MCMB ratio of 10/1 exhibits the highest value of 350 F/g, showing a ∼ 170% increase in specific capacitance.

  10. High adhesion transparent conducting films using graphene oxide hybrid carbon nanotubes

    International Nuclear Information System (INIS)

    Da, Shi-Xun; Wang, Jie; Geng, Hong-Zhang; Jia, Song-Lin; Xu, Chun-Xia; Li, Lin-Ge; Shi, Pei-Pei; Li, Guangfen

    2017-01-01

    Graphical abstract: The GO hybrid CNTs to fabricate TCFs could dramatically enhance the conductivity, adhesion, flatness, and wettability of the films, all these improvements are advantageous for optoelectronic applications. - Highlights: • TCFs were fabricated using GO/CNT hybrid inks by a simple spray method. • Conductivity of TCFs was improved through the hybrid of GO/CNT, sheet resistance of TCFs was 146 Ω/sq at the transmittance of 86.0% when the ratio of GO/CNT got 1.5:1.0. • The flatness and wettability of TCFs were improved dramatically, which is advantageous for the solution-based processing of organic electronics for spraying and printing. • The adhesion of the TCFs increased dramatically with the raise of the ratio GO/CNT hybrid. - Abstract: Flexible transparent conducting films (TCFs) with carbon nanotubes (CNTs) have attracted more and more attention for their wide range of potential applications. While, there are still some problems to be solved on several aspects. In this study, a graphene oxide/carbon nanotube (GO/CNT) hybrid TCF was fabricated through the simple spray coating method. GO sheets were introduced to form new electron transporting channels. It was found that the best optoelectronic property films were fabricated when the ratio of GO/CNT is 1.5:1.0, which the sheet resistance of the film was found to be 146 Ω/sq at the transmittance of 86.0%. Due to the two-dimensional structure and the oxidation groups of GO sheets, flatness and wettability of the electrode surface was improved obviously. Adhesion factor of the TCFs was calculated by the change of transparent and sheet resistance after trial test, the addition of GO sheets enhanced the adhesion dramatically and the mechanism was analyzed. Improvements of conductivity, flatness, wettability and adhesion above are all advantageous for the solution-based processing of organic electronics for spraying and printing.

  11. High adhesion transparent conducting films using graphene oxide hybrid carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Da, Shi-Xun; Wang, Jie; Geng, Hong-Zhang, E-mail: genghz@tjpu.edu.cn; Jia, Song-Lin; Xu, Chun-Xia; Li, Lin-Ge; Shi, Pei-Pei; Li, Guangfen

    2017-01-15

    Graphical abstract: The GO hybrid CNTs to fabricate TCFs could dramatically enhance the conductivity, adhesion, flatness, and wettability of the films, all these improvements are advantageous for optoelectronic applications. - Highlights: • TCFs were fabricated using GO/CNT hybrid inks by a simple spray method. • Conductivity of TCFs was improved through the hybrid of GO/CNT, sheet resistance of TCFs was 146 Ω/sq at the transmittance of 86.0% when the ratio of GO/CNT got 1.5:1.0. • The flatness and wettability of TCFs were improved dramatically, which is advantageous for the solution-based processing of organic electronics for spraying and printing. • The adhesion of the TCFs increased dramatically with the raise of the ratio GO/CNT hybrid. - Abstract: Flexible transparent conducting films (TCFs) with carbon nanotubes (CNTs) have attracted more and more attention for their wide range of potential applications. While, there are still some problems to be solved on several aspects. In this study, a graphene oxide/carbon nanotube (GO/CNT) hybrid TCF was fabricated through the simple spray coating method. GO sheets were introduced to form new electron transporting channels. It was found that the best optoelectronic property films were fabricated when the ratio of GO/CNT is 1.5:1.0, which the sheet resistance of the film was found to be 146 Ω/sq at the transmittance of 86.0%. Due to the two-dimensional structure and the oxidation groups of GO sheets, flatness and wettability of the electrode surface was improved obviously. Adhesion factor of the TCFs was calculated by the change of transparent and sheet resistance after trial test, the addition of GO sheets enhanced the adhesion dramatically and the mechanism was analyzed. Improvements of conductivity, flatness, wettability and adhesion above are all advantageous for the solution-based processing of organic electronics for spraying and printing.

  12. Polyoxometalate coordination induced controllable release of quinolone in hybrid film

    Science.gov (United States)

    Yang, Fan; Li, Yang; Lv, Yu-Guang; Zhou, Shu-Jing; Li, Si; Gao, Guang-Gang; Liu, Hong

    2018-05-01

    Due to some side effects of quinolones in vivo, it is an urgent issue to extend their new applications in vitro. In this paper, structure-determined vanadium-quinolone functionalized polymolybdates of (NH4)2 [(γ-Mo8O26){VO(CF)2}2] (1) and (NH4)2 [(γ-Mo8O26){VO(NF)2}2] (2) (CF = ciprofloxacin; NF = norfloxacin) have been designed and synthesized. Complex 1 or 2 features a γ-type [Mo8O26]4- polyanion functionalized by two monocapped vanadium-quinolone complexes. Different H-bonds and π···π interactions allow 1 or 2 to form a 2D layered structure at solid state. When complex 1 or 2 is transferred into polyvinyl alcohol (PVA) film, its release rate in solution is lower than that of CF- or NF-PVA film and thus forming a novel quinolone delivery system. This is the first time that slow release effect of quinolone is achieved by polyoxometalate coordination effect. The slow release of 1 or 2 in PVA film is mainly ascribed to the coordination of quinolone with polyoxometalate anions.

  13. The Effect of Nb on the Continuous Cooling Transformation Curves of Ultra-Thin Strip CASTRIP© Steels

    Directory of Open Access Journals (Sweden)

    Kristin R. Carpenter

    2015-10-01

    Full Text Available The effect of Nb on the hardenability of ultra-thin cast strip (UCS steels produced via the unique regime of rapid solidification, large austenite grain size, and inclusion engineering of the CASTRIP© process was investigated. Continuous cooling transformation (CCT diagrams were constructed for 0, 0.014, 0.024, 0.04, 0.06 and 0.08 wt% Nb containing UCS steels. Phase nomenclature for the identification of lower transformation product in low carbon steels was reviewed. Even a small addition of 0.014 wt% Nb showed a potent effect on hardenability, shifting the ferrite C-curve to the right and expanding the bainitic ferrite and acicular ferrite phase fields. Higher Nb additions increased hardenability further, suppressed the formation of ferrite to even lower cooling rates, progressively lowered the transformation start and finish temperatures and promoted the transformation of bainite instead of acicular ferrite. The latter was due to Nb suppressing the formation of allotriomorphic ferrite and allowing bainite to nucleate at prior austenite grain boundaries, a lower energy site than that for the intragranular nucleation of acicular ferrite at inclusions. Strength and hardness increased with increasing Nb additions, largely due to microstructural strengthening and solid solution hardening, but not from precipitation hardening.

  14. Ultra-thin and strong formvar-based membranes with controlled porosity for micro- and nano-scale systems

    Science.gov (United States)

    Auchter, Eric; Marquez, Justin; Stevens, Garrison; Silva, Rebecca; Mcculloch, Quinn; Guengerich, Quintessa; Blair, Andrew; Litchfield, Sebastian; Li, Nan; Sheehan, Chris; Chamberlin, Rebecca; Yarbro, Stephen L.; Dervishi, Enkeleda

    2018-05-01

    We present a methodology for developing ultra-thin and strong formvar-based membranes with controlled morphologies. Formvar is a thin hydrophilic and oleophilic polymer inert to most chemicals and resistant to radiation. The formvar-based membranes are viable materials as support structures in micro- and macro-scale systems depending on thinness and porosity control. Tunable sub-micron thick porous membranes with 20%–65% porosity were synthesized by controlling the ratios of formvar, glycerol, and chloroform. This synthesis process does not require complex separation or handling methods and allows for the production of strong, thin, and porous formvar-based membranes. An expansive array of these membrane characterizations including chemical compatibility, mechanical responses, wettability, as well as the mathematical simulations as a function of porosity has been presented. The wide range of chemical compatibility allows for membrane applications in various environments, where other polymers would not be suitable. Our formvar-based membranes were found to have an elastic modulus of 7.8 GPa, a surface free energy of 50 mN m‑1 and an average thickness of 125 nm. Stochastic model simulations indicate that formvar with the porosity of ∼50% is the optimal membrane formulation, allowing the most material transfer across the membrane while also withstanding the highest simulated pressure loadings before tearing. Development of novel, resilient and versatile membranes with controlled porosity offers a wide range of exciting applications in the fields of nanoscience, microfluidics, and MEMS.

  15. Fabrication of Through via Holes in Ultra-Thin Fused Silica Wafers for Microwave and Millimeter-Wave Applications

    Directory of Open Access Journals (Sweden)

    Xiao Li

    2018-03-01

    Full Text Available Through via holes in fused silica are a key infrastructure element of microwave and millimeter-wave circuits and 3D integration. In this work, etching through via holes in ultra-thin fused silica wafers using deep reactive-ion etching (DRIE and laser ablation was developed and analyzed. The experimental setup and process parameters for both methods are presented and compared. For DRIE, three types of mask materials including KMPR 1035 (Nippon Kayaku, Tokyo, Japan photoresist, amorphous silicon and chromium—with their corresponding optimized processing recipes—were tested, aiming at etching through a 100 μm fused silica wafer. From the experiments, we concluded that using chromium as the masking material is the best choice when using DRIE. However, we found that the laser ablation method with a laser pulse fluence of 2.89 J/cm2 and a pulse overlap of 91% has advantages over DRIE. The laser ablation method has a simpler process complexity, while offering a fair etching result. In particular, the sidewall profile angle is measured to be 75° to the bottom surface of the wafer, which is ideal for the subsequent metallization process. As a demonstration, a two-inch wafer with 624 via holes was processed using both technologies, and the laser ablation method showed better efficiency compared to DRIE.

  16. The design of an ultra-thin and multiple channels optical receiving antenna system with freeform lenses

    Science.gov (United States)

    Zhang, Lingyun; Cheng, Dewen; Hu, Yuan; Song, Weitao; Wang, Yongtian

    2014-11-01

    Visible Light Communications (VLC) has become an emerging area of research since it can provide higher data transmission speed and wider bandwidth. The white LEDs are very important components of the VLC system, because it has the advantages of higher brightness, lower power consumption, and a longer lifetime. More importantly, their intensity and color are modulatable. Besides the light source, the optical antenna system also plays a very important role in the VLC system since it determines the optical gain, effective working area and transmission rate of the VLC system. In this paper, we propose to design an ultra-thin and multiple channels optical antenna system by tiling multiple off-axis lenses, each of which consists of two reflective and two refractive freeform surfaces. The tiling of multiple systems and detectors but with different band filters makes it possible to design a wavelength division multiplexing VLC system to highly improve the system capacity. The field of view of the designed antenna system is 30°, the entrance pupil diameter is 1.5mm, and the thickness of the system is under 4mm. The design methods are presented and the results are discussed in the last section of this paper. Besides the optical gain is analyzed and calculated. The antenna system can be tiled up to four channels but without the increase of thickness.

  17. Design and analyses of an ultra-thin flat lens for wave front shaping in the visible

    International Nuclear Information System (INIS)

    Huang, Kai; Li, Yiyan; Tian, Xuelong; Zeng, Dajun; Gao, Xueli

    2015-01-01

    An ultra-thin flat lens is proposed for focusing circularly polarized light in the visible range. Anisotropic C-shaped nanoantennas with phase discontinuities are used to form the metasurface of the lens. The phase response of the C-shaped nanoantennas can be manipulated by simply rotating the angle of the unit nanoantenna. A 600 nm incident circularly polarized light is focused by the proposed techniques. Good agreements are observed by using our MoM and a commercial FDTD software package. The computation time spent by using MoM is approximately 10–100 times smaller than using FDTD. All the results show the proposed nanoantenna array has a great potential for nanoscale optical microscopy, solar cell energy conversion enhancement, as well as integrated optical circuits. - Highlights: • Successfully focusing a 600 nm light using a circularly C-shaped nanoantenna array. • The computation time spent by using MoM is approximately 10–100 times smaller than FDTD. • A good agreement is observed using our MoM to the classic FDTD method.

  18. Thickness effect of ultra-thin Ta2O5 resistance switching layer in 28 nm-diameter memory cell

    Science.gov (United States)

    Park, Tae Hyung; Song, Seul Ji; Kim, Hae Jin; Kim, Soo Gil; Chung, Suock; Kim, Beom Yong; Lee, Kee Jeung; Kim, Kyung Min; Choi, Byung Joon; Hwang, Cheol Seong

    2015-11-01

    Resistance switching (RS) devices with ultra-thin Ta2O5 switching layer (0.5-2.0 nm) with a cell diameter of 28 nm were fabricated. The performance of the devices was tested by voltage-driven current—voltage (I-V) sweep and closed-loop pulse switching (CLPS) tests. A Ta layer was placed beneath the Ta2O5 switching layer to act as an oxygen vacancy reservoir. The device with the smallest Ta2O5 thickness (0.5 nm) showed normal switching properties with gradual change in resistance in I-V sweep or CLPS and high reliability. By contrast, other devices with higher Ta2O5 thickness (1.0-2.0 nm) showed abrupt switching with several abnormal behaviours, degraded resistance distribution, especially in high resistance state, and much lower reliability performance. A single conical or hour-glass shaped double conical conducting filament shape was conceived to explain these behavioural differences that depended on the Ta2O5 switching layer thickness. Loss of oxygen via lateral diffusion to the encapsulating Si3N4/SiO2 layer was suggested as the main degradation mechanism for reliability, and a method to improve reliability was also proposed.

  19. Simplified tunnelling current calculation for MOS structures with ultra-thin oxides for conductive atomic force microscopy investigations

    International Nuclear Information System (INIS)

    Frammelsberger, Werner; Benstetter, Guenther; Stamp, Richard; Kiely, Janice; Schweinboeck, Thomas

    2005-01-01

    As charge tunnelling through thin and ultra-thin silicon dioxide layers is regarded as the driving force for MOS device degradation the determination and characterisation of electrically week spots is of paramount importance for device reliability and failure analysis. Conductive atomic force microscopy (C-AFM) is able to address this issue with a spatial resolution smaller than the expected breakdown spot. For the determination of the electrically active oxide thickness in practice an easy to use model with sufficient accuracy and which is largely independent of the oxide thickness is required. In this work a simplified method is presented that meets these demands. The electrically active oxide thickness is determined by matching of C-AFM voltage-current curves and a tunnelling current model, which is based on an analytical tunnelling current approximation. The model holds for both the Fowler-Nordheim tunnelling and the direct tunnelling regime with one single tunnelling parameter set. The results show good agreement with macroscopic measurements for gate voltages larger than approximately 0.5-1 V, and with microscopic C-AFM measurements. For this reason arbitrary oxides in the DT and the FNT regime may be analysed with high lateral resolution by C-AFM, without the need of a preselection of the tunnelling regime to be addressed

  20. Pure crystal orientation and anisotropic charge transport in large-area hybrid perovskite films

    KAUST Repository

    Cho, Nam Chul

    2016-11-10

    Controlling crystal orientations and macroscopic morphology is vital to develop the electronic properties of hybrid perovskites. Here we show that a large-area, orientationally pure crystalline (OPC) methylammonium lead iodide (MAPbI3) hybrid perovskite film can be fabricated using a thermal-gradient-assisted directional crystallization method that relies on the sharp liquid-to-solid transition of MAPbI3 from ionic liquid solution. We find that the OPC films spontaneously form periodic microarrays that are distinguishable from general polycrystalline perovskite materials in terms of their crystal orientation, film morphology and electronic properties. X-ray diffraction patterns reveal that the film is strongly oriented in the (112) and (200) planes parallel to the substrate. This film is structurally confined by directional crystal growth, inducing intense anisotropy in charge transport. In addition, the low trap-state density (7.9 × 1013 cm−3) leads to strong amplified stimulated emission. This ability to control crystal orientation and morphology could be widely adopted in optoelectronic devices.

  1. Ultra-thin fluoropolymer buffer layer as an anode stabilizer of organic light emitting devices

    International Nuclear Information System (INIS)

    Yang, Nam Chul; Lee, Jaeho; Song, Myung-Won; Ahn, Nari; Kim, Mu-Hyun; Lee, Songtaek; Chin, Byung Doo

    2007-01-01

    We have investigated the effect of thin fluoro-acrylic polymer as an anode stabilizer on the lifetime of an organic light emitting device (OLED). Surface chemical properties of commercial fluoropolymer, FC-722 (Fluorad(TM) of 3M), on indium-tin oxide (ITO) were characterized by x-ray photoemission spectroscopy. An OLED with 1 nm thick fluoropolymeric film showed identical brightness and efficiency behaviour and improved operational stability compared with the reference device with UV-O 3 treated ITO. The improvement in the lifetime was accompanied by the suppression of the voltage increase at the initial stage of constant-current driving, which can be attributed to the action of the FC-722 layer by smoothing the ITO surface. Fluoropolymer coating, therefore, improves the lifetime of the small molecular OLED by the simple and reliable anode-stabilizing process

  2. Ferromagnetism carried by highly delocalized hybrid states in Sc-doped ZnO thin films

    KAUST Repository

    Benali Kanoun, Mohammed

    2012-05-29

    We present first-principles results for Sc-doped ZnOthin films. Neighboring Sc atoms in the surface and/or subsurface layers are found to be coupled ferromagnetically, where only two of the possible configurations induce spin polarization. In the first configuration, the polarization is carried by the Sc d states as expected for transition metaldoping. However, there is a second configuration which is energetically favorable. It is governed by polarized hybrid states of the Zns, O p, and Sc d orbitals. Such highly delocalized states can be an important ingredient for understanding the magnetism of dopedZnOthin films.

  3. Immobilization of carbon nanotubes on functionalized graphene film grown by chemical vapor deposition and characterization of the hybrid material

    Directory of Open Access Journals (Sweden)

    Prashanta Dhoj Adhikari

    2014-01-01

    Full Text Available We report the surface functionalization of graphene films grown by chemical vapor deposition and fabrication of a hybrid material combining multi-walled carbon nanotubes and graphene (CNT–G. Amine-terminated self-assembled monolayers were prepared on graphene by the UV-modification of oxidized groups introduced onto the film surface. Amine-termination led to effective interaction with functionalized CNTs to assemble a CNT–G hybrid through covalent bonding. Characterization clearly showed no defects of the graphene film after the immobilization reaction with CNT. In addition, the hybrid graphene material revealed a distinctive CNT–G structure and p–n type electrical properties. The introduction of functional groups on the graphene film surface and fabrication of CNT–G hybrids with the present technique could provide an efficient, novel route to device fabrication.

  4. Tunneling magnetoresistance of ultra-thin Co-SiO2 granular films with narrow current channels

    International Nuclear Information System (INIS)

    Honda, S.; Hirata, M.; Ishimaru, M.

    2005-01-01

    We have constructed the tunneling magnetoresistance (TMR) junction of AuCr/SiO 2 /Co-SiO 2 /SiO 2 /AuCr with narrow current channels, where the TMR occurs in the Co-SiO 2 layer with 10-50 nm thickness. The magnetic properties are independent of thickness, while the TMR properties depend fairly on thickness. The current (I)-bias voltage (V B ) curve is nonlinear, namely the differential resistivity decreases with increasing V B , and also the magnetoresistance ratio decreases

  5. Passivation Effects in Copper Thin Films

    International Nuclear Information System (INIS)

    Wiederhirn, G.; Nucci, J.; Richter, G.; Arzt, E.; Balk, T. J.; Dehm, G.

    2006-01-01

    We studied the influence of a 10 nm AlxOy passivation on the stress-temperature behavior of 100 nm and 1 μm thick Cu films. At low temperatures, the passivation induces a large tensile stress increase in the 100 nm film; however, its effect on the 1 μm film is negligible. At high temperatures, the opposite behavior is observed; while the passivation does not change the 100 nm film behavior, it strengthens the 1 μm film by driving it deeper into compression. These observations are explained in light of a combination of constrained diffusional creep and dislocation dynamics unique to ultra-thin films

  6. Polyhydroxyalkanoate-based natural-synthetic hybrid copolymer films: A small-angle neutron scattering study

    International Nuclear Information System (INIS)

    Foster, L. John R.; Knott, Robert; Sanguanchaipaiwong, Vorapat; Holden, Peter J.

    2006-01-01

    Polyhydroxyalkanoates have attracted attention as biodegradable alternatives to conventional thermoplastics and as biomaterials. Through modification of their biosynthesis using Pseudomonas oleovorans, we have manipulated the material properties of these biopolyesters and produced a natural-synthetic hybrid copolymer of polyhydroxyoctanoate-block-diethylene glycol (PHO-b-DEG). A mixture of PHO and PHO-DEG were solvent cast from analytical grade chloroform and analysed using small-angle neutron scattering. A scattering pattern, easily distinguished above the background, was displayed by the films with a diffraction ring at q∼0.12 A -1 . This narrow ring of intensity is suggestive of a highly ordered system. Analysis of the diffraction pattern supported this concept and showed a d-spacing of approximately 50 A. In addition, conformation of the hybrid polymer chains can be manipulated to support their self-assembly into ordered microporous films

  7. Luminescent hybrid films obtained by covalent grafting of terbium complex to silica network

    International Nuclear Information System (INIS)

    Liu Fengyi; Fu Lianshe; Wang Jun; Liu Ze; Li Huanrong; Zhang Hongjie

    2002-01-01

    Luminescent hybrid thin films consisting of terbium complex covalently bonded to a silica-based network have been obtained in situ via a sol-gel approach. A new monomer, N-(4-benzoic acid-yl), N'-(propyltriethoxysilyl)urea (PABI), has been synthesized by grafting isocyanatopropyltriethoxysilane (ICPTES) to p-aminobenzoic acid and characterized by 1 H NMR, IR and MS. The monomer acts as a ligand for Tb 3+ ion and as a sol-gel precursor. Band emission from Tb 3+ ion due to an efficient ligand-to-metal energy transfer was observed by UV excitation. The decay curves of Tb 3+ in the hybrid films were measured. The energy difference between the triplet state energy of PABI and the 5 D 4 level of Tb 3+ ion falls in the exciting range to sensitize Tb 3+ ion fluorescence

  8. Large-area self-assembled reduced graphene oxide/electrochemically exfoliated graphene hybrid films for transparent electrothermal heaters

    Science.gov (United States)

    Sun, Hongyan; Chen, Ding; Ye, Chen; Li, Xinming; Dai, Dan; Yuan, Qilong; Chee, Kuan W. A.; Zhao, Pei; Jiang, Nan; Lin, Cheng-Te

    2018-03-01

    Graphene shows great promise as a high-efficiency electrothermal film for flexible transparent defoggers/defrosters. However, it remains a great challenge to achieve a good balance between the production cost and the properties of graphene films. Here, we proposed a cost-effective self-assembly method to fabricate high-performance, large-area graphene oxide/electrochemically exfoliated graphene hybrid films for heater applications. The self-assembled graphene hybrid films with the area of 20 × 20 cm2 could be transferred onto arbitrary substrates with nonplanar surfaces and simply patterned with the hard mask. After reduction by hydrogen iodide vapor followed by 800 °C thermal treatment, the hybrid films with the transmittance of 76.2% exhibit good heating characteristics and defogging performance, which reach a saturation temperature of up to 127.5 °C when 40 V was applied for 60 s.

  9. Hybrid organic-inorganic coatings and films containing conducting polyaniline nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Špírková, Milena; Stejskal, Jaroslav; Prokeš, J.

    2004-01-01

    Roč. 212, č. 1 (2004), s. 343-348 ISSN 1022-1360. [Electrical and Related Properties of Polymers and Other Organic Solids /9./. Prague, 14.07.2002-18.07.2002] R&D Projects: GA AV ČR KSK4050111; GA ČR GA203/01/0735 Institutional research plan: CEZ:AV0Z4050913 Keywords : atomic force microscopy * films * hybrid networks Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.691, year: 2004

  10. Optical properties of self assembled oriented island evolution of ultra-thin gold layers

    International Nuclear Information System (INIS)

    Worsch, Christian; Kracker, Michael; Wisniewski, Wolfgang; Rüssel, Christian

    2012-01-01

    Gold layers with a thickness of only 8 to 21 nm were sputtered on soda–lime–silica glasses. Subsequent annealing at 300 and 400 °C for 1 and 24 h resulted in the formation of separated round gold particles with diameters from 8 to 200 nm. Crystal orientations were described using X-ray diffraction and electron backscatter diffraction. The gold particles are oriented with their (111) planes perpendicular to the surface. Most gold nano particles are single crystalline, some particles are twinned. Thermal annealing of sputtered gold layers resulted in purple samples with a coloration comparable to that of gold ruby glasses. The color can be controlled by the thickness of the sputtered gold layer and the annealing conditions. The simple method of gold film preparation and the annealing temperature dependent properties of the layers make them appropriate for practical applications. - Highlights: ► We produce gold nano particle layers on amorphous substrates. ► Thin sputtered gold layers were annealed at low temperatures. ► Various colors can be achieved reproducibly and UV–vis-NIR spectra are reported. ► A 111-texture of the particles is described as well as twinning. ► The process is suitable for mass production.

  11. Preparation, characterization and electrocatalytic behavior of zinc oxide/zinchexacyanoferrate and ruthenium oxide hexacyanoferrate hybrid film-modified electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Chu, H.-W.; Thangamuthu, R. [Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, No. 1, Section 3, Chung-Hsiao East Road, Taipei 106, Taiwan (China); Chen, S.-M. [Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, No. 1, Section 3, Chung-Hsiao East Road, Taipei 106, Taiwan (China)], E-mail: smchen78@ms15.hinet.net

    2008-02-15

    Polynuclear mixed-valent hybrid films of zinc oxide/zinchexacyanoferrate and ruthenium oxide hexacyanoferrate (ZnO/ZnHCF-RuOHCF) have been deposited on electrode surfaces from H{sub 2}SO{sub 4} solution containing Zn(NO{sub 3}){sub 2}, RuCl{sub 3} and K{sub 3}[Fe(CN){sub 6}] by potentiodynamic cycling method. Simultaneous cyclic voltammetry and electrochemical quartz crystal microbalance (EQCM) measurements demonstrate the steady growth of hybrid film. Surface morphology of hybrid film was investigated using scanning electron microscopy (SEM). Energy dispersive spectrometer (EDS) data confirm existence of zinc oxide and ruthenium oxide hexacyanoferrate (RuOHCF) in the hybrid film. The effect of type of monovalent cations on the redox behavior of hybrid film was investigated. In pure supporting electrolyte, electrochemical responses of Ru{sup II/III} redox transition occurring at negative potential region resemble with that of a surface immobilized redox couple. The electrocatalytic activity of ZnO/ZnHCF-RuOHCF hybrid film was investigated towards oxidation of epinephrine, dopamine and L-cysteine, and reduction of S{sub 2}O{sub 8}{sup 2-} and SO{sub 5}{sup 2-} as well as IO{sub 3}{sup -} using cyclic voltammetry and rotating ring disc electrode (RRDE) techniques.

  12. Hybrid Solar Cell with TiO2 Film: BBOT Polymer and Copper Phthalocyanine as Sensitizer

    Directory of Open Access Journals (Sweden)

    Saptadip Saha

    2016-01-01

    Full Text Available An organic-inorganic hybrid solar cell was fabricated using Titanium dioxide (TiO2: 2,5-bis(5-tert-butyl-2-benzoxazolyl thiophene (BBOT film and Copper Phthalocyanine (CuPc as a sensitizer. BBOT was used in photodetector in other reported research works, but as per best of our knowledge, it was not implemented in solar cells till date. The blend of TiO2: BBOT blend was used to fabricate the film on ITO-coated glass and further a thin layer of CuPc was coated on the film. This was acted as photoanode and another ITO coated glass with a platinum coating was used as a counter electrode (cathode. An optimal blend of acetonitrile (solvent (50-100%, 1,3-dimethylimidazolium iodide (10-25%, iodine (2.5-10% and lithium iodide, pyridine derivative and thiocyanate was used as electrolytes in the hybrid solar cell. The different structural, optical and electrical characteristics were measured. The Hybrid solar cell showed a maximum conversion efficiency of 6.51%.

  13. Micropatterned 2D Hybrid Perovskite Thin Films with Enhanced Photoluminescence Lifetimes.

    Science.gov (United States)

    Kamminga, Machteld E; Fang, Hong-Hua; Loi, Maria Antonietta; Ten Brink, Gert H; Blake, Graeme R; Palstra, Thomas T M; Ten Elshof, Johan E

    2018-04-18

    The application of luminescent materials in display screens and devices requires micropatterned structures. In this work, we have successfully printed microstructures of a two-dimensional (2D), orange-colored organic/inorganic hybrid perovskite ((C 6 H 5 CH 2 NH 3 ) 2 PbI 4 ) using two different soft lithography techniques. Notably, both techniques yield microstructures with very high aspect ratios in the range of 1.5-1.8. X-ray diffraction reveals a strong preferential orientation of the crystallites along the c-axis in both patterned structures, when compared to nonpatterned, drop-casted thin films. Furthermore, (time-resolved) photoluminescence (PL) measurements reveal that the optical properties of (C 6 H 5 CH 2 NH 3 ) 2 PbI 4 are conserved upon patterning. We find that the larger grain sizes of the patterned films with respect to the nonpatterned film give rise to an enhanced PL lifetime. Thus, our results demonstrate easy and cost-effective ways to manufacture patterns of 2D organic/inorganic hybrid perovskites, while even improving their optical properties. This demonstrates the potential use of color-tunable 2D hybrids in optoelectronic devices.

  14. Dopamine/TiO{sub 2} hybrid thin films prepared by the liquid phase deposition method

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez-Tauste, David [Departament de Quimica, Universitat Autonoma de Barcelona, Campus UAB, Edifici Cn, 08290 Cerdanyola del Valles, Barcelona (Spain)], E-mail: davidg@qf.uab.es; Domenech, Xavier [Departament de Quimica, Universitat Autonoma de Barcelona, Campus UAB, Edifici Cn, 08290 Cerdanyola del Valles, Barcelona (Spain); Domingo, Concepcion [Instituto de Ciencia de Materiales (CSIC), Campus UAB, 08290 Cerdanyola del Valles, Barcelona (Spain); Ayllon, Jose A. [Departament de Quimica, Universitat Autonoma de Barcelona, Campus UAB, Edifici Cn, 08290 Cerdanyola del Valles, Barcelona (Spain)

    2008-04-30

    Liquid phase deposition method is applied to one-step production of a hybrid material composed by dopamine(DA) and TiO{sub 2} anatase. An optimized amount of the enediol derivative is added to a fluoride titania precursor aqueous solution in order to entrap this modifier within the growing TiO{sub 2}, yielding a DA/TiO{sub 2} nanocomposite material. Uniform, well-adhered and brown-colored thin films are deposited on indium tin oxide covered glass substrate. The DA/TiO{sub 2} hybrid material has been characterized by infrared spectroscopy, electronic microscopy, X-ray diffraction and UV-vis spectroscopy. The formation of the hybrid material seems to be reasonably explained by linkage of different TiO{sub 2} nanocrystallites taking advantage of both enediol and amine groups of DA.

  15. Thin film hybrid Josephson junctions with Co doped Ba-122

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Stefan; Doering, Sebastian; Schmidl, Frank; Tympel, Volker; Grosse, Veit; Seidel, Paul [Friedrich-Schiller-Universitaet Jena, Institut fuer Festkoerperphysik, Helmholtzweg 5, 07743 Jena (Germany); Haindl, Silvia; Iida, Kazumasa; Kurth, Fritz; Holzapfel, Bernhard [IFW Dresden, Institut fuer Metallische Werkstoffe, Helmholtzstrasse 20, 01069 Dresden (Germany); Moench, Ingolf [IFW Dresden, Institut fuer Integrative Nanowissenschaften, Helmholtzstrasse 20, 01069 Dresden (Germany)

    2011-07-01

    Josephson junctions are a strong tool to investigate fundamental superconducting properties, such as gap behaviour, dependencies from external fields and the order parameter symmetry. Finding secure values enables the possibility of theoretical descriptions to understand the physical processes within the new iron-based superconductors. Based on Co-doped BaFe{sub 2}As{sub 2} (Ba-122) layers produced via pulsed laser deposition (PLD) on (La,Sr)(Al,Ta)O{sub 3} substrates, we manufactured superconductor-normal conductor-superconductor (S-N-S) junctions structures by using photolithography, ion beam etching as well as insulating SiO{sub 2} layers. We present working Ba-122/Au/PbIn thin film Josephson junctions with different contact areas and barrier thicknesses, their temperature dependence and response to microwave irradiation. The calculated I{sub c}R{sub N} product is in the range of a couple of microvolts.

  16. Enhancement of sp3 hybridized C in amorphous carbon films by Ar ion bombardment and Si incorporation

    International Nuclear Information System (INIS)

    Jung, Hae-Suk; Park, Hyung-Ho; Mendieta, I.R.; Smith, D.A.

    2003-01-01

    We report an effective method of increasing the sp 3 hybridization fraction in sputtered amorphous carbon (a-C) film by the combination of Ar ion bombardment and Si incorporation. In the deposition of an a-C film, Ar ion bombardment by controlling the applied bias voltage plays a role in creating high stress in film and causes the local bonding configuration to change to a sp 3 hybridized bond. Simultaneously, the incorporated Si in an a-C network breaks the sp 2 hybridized bonded ring and promotes the formation of a sp 3 hybridized bond. This enhancement of the sp 3 hybridized bonding characteristic is maximized for an a-C film with 23 at. % of Si and 100-150 V of applied bias voltage. In this region, the increase of resistivity, optical band gap, and mechanical hardness of a-C is attributed to the reduction of the sp 2 hybridized bonded ring and increased fraction of the sp 3 hybridized bond. However, at a higher bias voltage above 150 V, the enhancement effect is reduced due to the resputtering and thermally activated reconversion of a sp 3 to a sp 2 hybridized bond

  17. Solution-processing of ultra-thin CdTe/ZnO nanocrystal solar cells

    International Nuclear Information System (INIS)

    MacDonald, Brandon I.; Gengenbach, Thomas R.; Watkins, Scott E.; Mulvaney, Paul; Jasieniak, Jacek J.

    2014-01-01

    We have carried out a detailed study into how modifications of the physical, chemical and optical properties of solution-processed, nanocrystalline CdTe layers influence the photovoltaic performance of sintered CdTe/ZnO nanocrystal solar cells. Such solar cells are fabricated through layer-by-layer assembly, which is enabled through an inter layer chemical and thermal treatment cycle. In this manner we are able to fabricate working solar cells with sintered CdTe layers as low as 90 nm, provided that grain size is precisely controlled. We show that the extent of grain growth achieved during the CdTe sintering process is strongly dependent on nanocrystal surface chemistry and chemical environment, with the removal of the organic capping ligands and the introduction of CdCl 2 prior to annealing leading to greatly enhanced growth. Due to the air processing involved and the nanocrystalline nature of the CdTe, the overall performance of these solar cells is shown to be strongly dependent on both annealing temperature and time, with optimal results requiring a balance between crystal growth and degradation due to oxidation. Using this simple bi-layer device structure, optimized treatment conditions result in power conversion efficiencies of up to 7.7% and peak internal quantum efficiencies in excess of 95%. - Highlights: • We study the growth of nanocrystalline CdTe thin films from colloidal nanocrystals. • We examine the CdTe growth profiles as a function of surface chemistry. • We show that nanocrystalline CdTe is susceptible to oxidation under air annealing. • We show how this oxidation influences performance in CdTe/ZnO solar cells. • We demonstrate CdTe/ZnO solar cells with an efficiency of 7.7% fabricated in air

  18. Organic/hybrid thin films deposited by matrix-assisted pulsed laser evaporation (MAPLE)

    Science.gov (United States)

    Stiff-Roberts, Adrienne D.; Ge, Wangyao

    2017-12-01

    Some of the most exciting materials research in the 21st century attempts to resolve the challenge of simulating, synthesizing, and characterizing new materials with unique properties designed from first principles. Achievements in such development for organic and organic-inorganic hybrid materials make them important options for electronic and/or photonic devices because they can impart multi-functionality, flexibility, transparency, and sustainability to emerging systems, such as wearable electronics. Functional organic materials include small molecules, oligomers, and polymers, while hybrid materials include inorganic nanomaterials (such as zero-dimensional quantum dots, one-dimensional carbon nanotubes, or two-dimensional nanosheets) combined with organic matrices. A critically important step to implementing new electronic and photonic devices using such materials is the processing of thin films. While solution-based processing is the most common laboratory technique for organic and hybrid materials, vacuum-based deposition has been critical to the commercialization of organic light emitting diodes based on small molecules, for example. Therefore, it is desirable to explore vacuum-based deposition of organic and hybrid materials that include larger macromolecules, such as polymers. This review article motivates the need for physical vapor deposition of polymeric and hybrid thin films using matrix-assisted pulsed laser evaporation (MAPLE), which is a type of pulsed laser deposition. This review describes the development of variations in the MAPLE technique, discusses the current understanding of laser-target interactions and growth mechanisms for different MAPLE variations, surveys demonstrations of MAPLE-deposited organic and hybrid materials for electronic and photonic devices, and provides a future outlook for the technique.

  19. Hemocompatibility and biocompatibility of antibacterial biomimetic hybrid films

    Energy Technology Data Exchange (ETDEWEB)

    Coll Ferrer, M. Carme [Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA 19104 (United States); Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104 (United States); Eckmann, Uriel N. [Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA 19104 (United States); Composto, Russell J. [Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104 (United States); Eckmann, David M., E-mail: eckmanndm@uphs.upenn.edu [Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA 19104 (United States)

    2013-11-01

    In previous work, we developed novel antibacterial hybrid coatings based on dextran containing dispersed Ag NPs (∼ 5 nm, DEX-Ag) aimed to offer dual protection against two of the most common complications associated with implant surgery, infections and rejection of the implant. However, their blood-material interactions are unknown. In this study, we assess the hemocompatibility and biocompatibility of DEX-Ag using fresh blood and two cell lines of the immune system, monocytes (THP-1 cells) and macrophages (PMA-stimulated THP-1 cells). Glass, polyurethane (PU) and bare dextran (DEX) were used as reference surfaces. PU, DEX and DEX-Ag exhibited non-hemolytic properties. Relative to glass (100%), platelet attachment on PU, DEX and DEX-Ag was 15%, 10% and 34%, respectively. Further, we assessed cell morphology and viability, pro-inflammatory cytokines expression (TNF-α and IL-1β), pro-inflammatory eicosanoid expression (Prostaglandin E{sub 2}, PGE{sub 2}) and release of reactive oxygen species (ROS, superoxide and H{sub 2}O{sub 2}) following incubation of the cells with the surfaces. The morphology and cell viability of THP-1 cells were not affected by DEX-Ag whereas DEX-Ag minimized spreading of PMA-stimulated THP-1 cells and caused a reduction in cell viability (16% relative to other surfaces). Although DEX-Ag slightly enhanced release of ROS, the expression of pro-inflammatory cytokines remained minimal with similar levels of PGE{sub 2}, as compared to the other surfaces studied. These results highlight low toxicity of DEX-Ag and hold promise for future applications in vivo. - Highlights: • We examined specific blood-contact reactions of dextran doped with Ag NPs coatings. • Biocompatibility was assessed with THP-1 cells and PMA-stimulated THP-1 cells. • Glass, polyurethane and dextran were used as reference surfaces. • Hybrid coatings exhibited non-hemolytic properties. • Low toxicity, inflammatory response and ROS suggest potential for in vivo use.

  20. Hybrid chemical vapour and nanoceramic aerosol assisted deposition for multifunctional nanocomposite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Warwick, Michael E.A.; Dunnill, Charles W.; Goodall, Josie; Darr, Jawwad A.; Binions, Russell, E-mail: uccarbi@ucl.ac.uk

    2011-07-01

    Hybrid atmospheric pressure chemical vapour and aerosol assisted deposition via the reaction of vanadium acetylacetonate and a suspension of preformed titanium dioxide or cerium dioxide nanoparticles, led to the production of vanadium dioxide nanocomposite thin films on glass substrates. The preformed nanoparticle oxides used for the aerosol were synthesised using a continuous hydrothermal flow synthesis route involving the rapid reaction of a metal salt solution with a flow of supercritical water in a flow reactor. Multifunctional nanocomposite thin films from the hybrid deposition process were characterised using scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The functional properties of the films were evaluated using variable temperature optical measurements to assess thermochromic behaviour and methylene blue photodecolourisation experiments to assess photocatalytic activity. The tests show that the films are multifunctional in that they are thermochromic (having a large change in infra-red reflectivity upon exceeding the thermochromic transition temperature) and have significant photocatalytic activity under irradiation with 254 nm light.

  1. Nanocomposite metal amorphous-carbon thin films deposited by hybrid PVD and PECVD technique.

    Science.gov (United States)

    Teixeira, V; Soares, P; Martins, A J; Carneiro, J; Cerqueira, F

    2009-07-01

    Carbon based films can combine the properties of solid lubricating graphite structure and hard diamond crystal structure, i.e., high hardness, chemical inertness, high thermal conductivity and optical transparency without the crystalline structure of diamond. Issues of fundamental importance associated with nanocarbon coatings are reducing stress, improving adhesion and compatibility with substrates. In this work new nanocomposite coatings with improved toughness based in nanocrystalline phases of metals and ceramics embedded in amorphous carbon matrix are being developed within the frame of a research project: nc-MeNxCy/a-C(Me) with Me = Mo, Si, Al, Ti, etc. Carbide forming metal/carbon (Me/C) composite films with Me = Mo, W or Ti possess appropriate properties to overcome the limitation of pure DLC films. These novel coating architectures will be adopted with the objective to decrease residual stress, improve adherence and fracture toughness, obtain low friction coefficient and high wear-resistance. Nanocomposite DLC's films were deposited by hybrid technique using a PVD-Physically Vapor Deposition (magnetron sputtering) and Plasma Enhanced Chemical Vapor Deposition (PECVD), by the use of CH4 gas. The parameters varied were: deposition time, substrate temperature (180 degrees C) and dopant (Si + Mo) of the amorphous carbon matrix. All the depositions were made on silicon wafers and steel substrates precoated with a silicon inter-layer. The characterisation of the film's physico-mechanical properties will be presented in order to understand the influence of the deposition parameters and metal content used within the a-C matrix in the thin film properties. Film microstructure and film hybridization state was characterized by Raman Spectroscopy. In order to characterize morphology SEM and AFM will be used. Film composition was measured by Energy-Dispersive X-ray analysis (EDS) and by X-ray photoelectron spectroscopy (XPS). The contact angle for the produced DLC's on

  2. Influence of Hybrid Perovskite Fabrication Methods on Film Formation, Electronic Structure, and Solar Cell Performance

    Science.gov (United States)

    Schnier, Tobias; Emara, Jennifer; Olthof, Selina; Meerholz, Klaus

    2017-01-01

    Hybrid organic/inorganic halide perovskites have lately been a topic of great interest in the field of solar cell applications, with the potential to achieve device efficiencies exceeding other thin film device technologies. Yet, large variations in device efficiency and basic physical properties are reported. This is due to unintentional variations during film processing, which have not been sufficiently investigated so far. We therefore conducted an extensive study of the morphology and electronic structure of a large number of CH3NH3PbI3 perovskite where we show how the preparation method as well as the mixing ratio of educts methylammonium iodide and lead(II) iodide impact properties like film formation, crystal structure, density of states, energy levels, and ultimately the solar cell performance. PMID:28287555

  3. Controllable growth of stable germanium dioxide ultra-thin layer by means of capacitively driven radio frequency discharge

    Energy Technology Data Exchange (ETDEWEB)

    Svarnas, P., E-mail: svarnas@ece.upatras.gr [High Voltage Laboratory, Department of Electrical and Computer Engineering, University of Patras, Rion 26 504, Patras (Greece); Botzakaki, M.A. [Department of Physics, University of Patras, Rion 26 504 (Greece); Skoulatakis, G.; Kennou, S.; Ladas, S. [Surface Science Laboratory, Department of Chemical Engineering, University of Patras, Rion 26 504 (Greece); Tsamis, C. [NCSR “Demokritos”, Institute of Advanced Materials, Physicochemical Processes, Nanotechnology & Microsystems, Aghia Paraskevi 15 310, Athens (Greece); Georga, S.N.; Krontiras, C.A. [Department of Physics, University of Patras, Rion 26 504 (Greece)

    2016-01-29

    It is well recognized that native oxide of germanium is hygroscopic and water soluble, while germanium dioxide is thermally unstable and it is converted to volatile germanium oxide at approximately 400 °C. Different techniques, implementing quite complicated plasma setups, gas mixtures and substrate heating, have been used in order to grow a stable germanium oxide. In the present work a traditional “RF diode” is used for germanium oxidation by cold plasma. Following growth, X-ray photoelectron spectroscopy demonstrates that traditional capacitively driven radio frequency discharges, using molecular oxygen as sole feedstock gas, provide the possibility of germanium dioxide layer growth in a fully reproducible and controllable manner. Post treatment ex-situ analyses on day-scale periods disclose the stability of germanium oxide at room ambient conditions, offering thus the ability to grow (ex-situ) ultra-thin high-k dielectrics on top of germanium oxide layers. Atomic force microscopy excludes any morphological modification in respect to the bare germanium surface. These results suggest a simple method for a controllable and stable germanium oxide growth, and contribute to the challenge to switch to high-k dielectrics as gate insulators for high-performance metal-oxide-semiconductor field-effect transistors and to exploit in large scale the superior properties of germanium as an alternative channel material in future technology nodes. - Highlights: • Simple one-frequency reactive ion etcher develops GeO{sub 2} thin layers controllably. • The layers remain chemically stable at ambient conditions over day-scale periods. • The layers are unaffected by the ex-situ deposition of high-k dielectrics onto them. • GeO{sub 2} oxidation and high-k deposition don't affect the Ge morphology significantly. • These conditions contribute to improved Ge-based MOS structure fabrication.

  4. Employing Si solar cell technology to increase efficiency of ultra-thin Cu(In,Ga)Se2 solar cells.

    Science.gov (United States)

    Vermang, Bart; Wätjen, Jörn Timo; Fjällström, Viktor; Rostvall, Fredrik; Edoff, Marika; Kotipalli, Ratan; Henry, Frederic; Flandre, Denis

    2014-10-01

    Reducing absorber layer thickness below 500 nm in regular Cu(In,Ga)Se 2 (CIGS) solar cells decreases cell efficiency considerably, as both short-circuit current and open-circuit voltage are reduced because of incomplete absorption and high Mo/CIGS rear interface recombination. In this work, an innovative rear cell design is developed to avoid both effects: a highly reflective rear surface passivation layer with nano-sized local point contact openings is employed to enhance rear internal reflection and decrease the rear surface recombination velocity significantly, as compared with a standard Mo/CIGS rear interface. The formation of nano-sphere shaped precipitates in chemical bath deposition of CdS is used to generate nano-sized point contact openings. Evaporation of MgF 2 coated with a thin atomic layer deposited Al 2 O 3 layer, or direct current magnetron sputtering of Al 2 O 3 are used as rear surface passivation layers. Rear internal reflection is enhanced substantially by the increased thickness of the passivation layer, and also the rear surface recombination velocity is reduced at the Al 2 O 3 /CIGS rear interface. (MgF 2 /)Al 2 O 3 rear surface passivated ultra-thin CIGS solar cells are fabricated, showing an increase in short circuit current and open circuit voltage compared to unpassivated reference cells with equivalent CIGS thickness. Accordingly, average solar cell efficiencies of 13.5% are realized for 385 nm thick CIGS absorber layers, compared with 9.1% efficiency for the corresponding unpassivated reference cells.

  5. Hadron-therapy beam monitoring: Towards a new generation of ultra-thin p-type silicon strip detectors

    International Nuclear Information System (INIS)

    Bouterfa, M.; Aouadi, K.; Bertrand, D.; Olbrechts, B.; Delamare, R.; Raskin, J. P.; Gil, E. C.; Flandre, D.

    2011-01-01

    Hadron-therapy has gained increasing interest for cancer treatment especially within the last decade. System commissioning and quality assurance procedures impose to monitor the particle beam using 2D dose measurements. Nowadays, several monitoring systems exist for hadron-therapy but all show a relatively high influence on the beam properties: indeed, most devices consist of several layers of materials that degrade the beam through scattering and energy losses. For precise treatment purposes, ultra-thin silicon strip detectors are investigated in order to reduce this beam scattering. We assess the beam size increase provoked by the Multiple Coulomb Scattering when passing through Si, to derive a target thickness. Monte-Carlo based simulations show a characteristic scattering opening angle lower than 1 mrad for thicknesses below 20 μm. We then evaluated the fabrication process feasibility. We successfully thinned down silicon wafers to thicknesses lower than 10 μm over areas of several cm 2 . Strip detectors are presently being processed and they will tentatively be thinned down to 20 μm. Moreover, two-dimensional TCAD simulations were carried out to investigate the beam detector performances on p-type Si substrates. Additionally, thick and thin substrates have been compared thanks to electrical simulations. Reducing the pitch between the strips increases breakdown voltage, whereas leakage current is quite insensitive to strips geometrical configuration. The samples are to be characterized as soon as possible in one of the IBA hadron-therapy facilities. For hadron-therapy, this would represent a considerable step forward in terms of treatment precision. (authors)

  6. Employing Si solar cell technology to increase efficiency of ultra-thin Cu(In,Ga)Se2 solar cells

    Science.gov (United States)

    Vermang, Bart; Wätjen, Jörn Timo; Fjällström, Viktor; Rostvall, Fredrik; Edoff, Marika; Kotipalli, Ratan; Henry, Frederic; Flandre, Denis

    2014-01-01

    Reducing absorber layer thickness below 500 nm in regular Cu(In,Ga)Se2 (CIGS) solar cells decreases cell efficiency considerably, as both short-circuit current and open-circuit voltage are reduced because of incomplete absorption and high Mo/CIGS rear interface recombination. In this work, an innovative rear cell design is developed to avoid both effects: a highly reflective rear surface passivation layer with nano-sized local point contact openings is employed to enhance rear internal reflection and decrease the rear surface recombination velocity significantly, as compared with a standard Mo/CIGS rear interface. The formation of nano-sphere shaped precipitates in chemical bath deposition of CdS is used to generate nano-sized point contact openings. Evaporation of MgF2 coated with a thin atomic layer deposited Al2O3 layer, or direct current magnetron sputtering of Al2O3 are used as rear surface passivation layers. Rear internal reflection is enhanced substantially by the increased thickness of the passivation layer, and also the rear surface recombination velocity is reduced at the Al2O3/CIGS rear interface. (MgF2/)Al2O3 rear surface passivated ultra-thin CIGS solar cells are fabricated, showing an increase in short circuit current and open circuit voltage compared to unpassivated reference cells with equivalent CIGS thickness. Accordingly, average solar cell efficiencies of 13.5% are realized for 385 nm thick CIGS absorber layers, compared with 9.1% efficiency for the corresponding unpassivated reference cells. PMID:26300619

  7. Photovoltammetric behavior and photoelectrochemical determination of p-phenylenediamine on CdS quantum dots and graphene hybrid film

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Yuhan; Yan, Kai; Liu, Yong; Zhang, Jingdong, E-mail: zhangjd@mail.hust.edu.cn

    2015-07-16

    Highlights: • Photovoltammetric behavior of PPD on CdS–GS hybrid film was studied. • GS doped in CdS greatly improved the photoelectrochemical response of PPD. • CV of PPD on CdS–GS film became a sigmoidal shape under photoirradiation. • Novel photoelectrochemical strategy for PPD determination was developed. - Abstract: A photoelectroactive film composed of CdS quantum dots and graphene sheets (GS) was coated on F-doped SnO{sub 2} (FTO) conducting glass for studying the electrochemical response of p-phenylenediamine (PPD) under photoirradiation. The result indicated that the cyclic voltammogram of PPD on CdS–GS hybrid film became sigmoidal in shape after exposed under visible light, due to the photoelectrocatalytic reaction. Such a photovoltammetric response was used to rapidly optimize the photoelectrocatalytic activity of hybrid films composed of different ratios of CdS to GS toward PPD. The influences of scan rate and pH on the photovoltammetric behavior of PPD on CdS–GS film revealed that although the controlled step for electrochemical process was not changed under photoirradiation, more electrons than protons might participate the photoelectrocatalytic process. Furthermore, the photoelectroactive CdS–GS hybrid film was explored for PPD determination based on the photocurrent response of film toward PPD. Under optimal conditions, the photocurrent signal on CdS–GS film was linearly proportional to the concentration of PPD ranging from 1.0 × 10{sup −7} to 3.0 × 10{sup −6} mol L{sup −1}, with a detection limit (3S/N) of 4.3 × 10{sup −8} mol L{sup −1}. Our work based on CdS–GS hybrid film not only demonstrated a new facile photovoltammetric way to study the photoinduced electron transfer process of PPD, but also developed a sensitive photoelectrochemical strategy for PPD determination.

  8. Excitation of epsilon-near-zero resonance in ultra-thin indium tin oxide shell embedded nanostructured optical fiber.

    Science.gov (United States)

    Minn, Khant; Anopchenko, Aleksei; Yang, Jingyi; Lee, Ho Wai Howard

    2018-02-05

    We report a novel optical waveguide design of a hollow step index fiber modified with a thin layer of indium tin oxide (ITO). We show an excitation of highly confined waveguide mode in the proposed fiber near the wavelength where permittivity of ITO approaches zero. Due to the high field confinement within thin ITO shell inside the fiber, the epsilon-near-zero (ENZ) mode can be characterized by a peak in modal loss of the hybrid waveguide. Our results show that such in-fiber excitation of ENZ mode is due to the coupling of the guided core mode to the thin-film ENZ mode. We also show that the phase matching wavelength, where the coupling takes place, varies depending on the refractive index of the constituents inside the central bore of the fiber. These ENZ nanostructured optical fibers have many potential applications, for example, in ENZ nonlinear and magneto-optics, as in-fiber wavelength-dependent filters, and as subwavelength fluid channel for optical and bio-photonic sensing.

  9. Ultra-tough and strong, hybrid thin films based on ionically crosslinked polymers and 2D inorganic platelets

    Science.gov (United States)

    Ji, Dong Hwan; Choi, Suji; Kim, Jaeyun; nanobiomaterials lab Team

    Integration of high strength and toughness tend to be mutually exclusive and synthesized hybrid films with superior mechanical properties have been difficult to fabricate controllable shapes and various scales. Although diverse synthesized hybrid films consisting of organic matrix and inorganic materials with brick-and-mortar structure, show improved mechanical properties, these films are still limited in toughness and fabrication methods. Herein, we report ultra-tough and strong hybrid thin films with self-assembled uniform microstructures with controllable shapes and various scale based on hydrogel-mediated process. Ca2+-crosslinking in alginate chains and well-aligned alumina platelets in alginate matrix lead to a synergistic enhancement of strength and toughness in the resulting film. Consequentially, Ca2+-crosslinked Alg/Alu films showed outstanding toughness of 29 MJ m-3 and tensile strength of 160 MPa. Furthermore, modifying Alu surface with polyvinylpyrrolidone (PVP), tensile strength was further improved up to 200 MPa. Our results suggest an alternative approach to design and processing of self-assembled hydrogel-mediated hybrid films with outstanding mechanical properties.

  10. Low temperature excitonic spectroscopy and dynamics as a probe of quality in hybrid perovskite thin films.

    Science.gov (United States)

    Sarang, Som; Ishihara, Hidetaka; Chen, Yen-Chang; Lin, Oliver; Gopinathan, Ajay; Tung, Vincent C; Ghosh, Sayantani

    2016-10-19

    We have developed a framework for using temperature dependent static and dynamic photoluminescence (PL) of hybrid organic-inorganic perovskites (PVSKs) to characterize lattice defects in thin films, based on the presence of nanodomains at low temperature. Our high-stability PVSK films are fabricated using a novel continuous liquid interface propagation technique, and in the tetragonal phase (T > 120 K), they exhibit bi-exponential recombination from free charge carriers with an average PL lifetime of ∼200 ns. Below 120 K, the emergence of the orthorhombic phase is accompanied by a reduction in lifetimes by an order of magnitude, which we establish to be the result of a crossover from free carrier to exciton-dominated radiative recombination. Analysis of the PL as a function of excitation power at different temperatures provides direct evidence that the exciton binding energy is different in the two phases, and using these results, we present a theoretical approach to estimate this variable binding energy. Our findings explain this anomalous low temperature behavior for the first time, attributing it to an inherent fundamental property of the hybrid PVSKs that can be used as an effective probe of thin film quality.

  11. CMOS compatible fabrication of flexible and semi-transparent FeRAM on ultra-thin bulk monocrystalline silicon (100) fabric

    KAUST Repository

    Ghoneim, Mohamed T.; Hanna, Amir; Hussain, Muhammad Mustafa

    2014-01-01

    Commercialization of flexible electronics requires reliable, high performance, ultra-compact and low power devices. To achieve them, we fabricate traditional electronics on bulk mono-crystalline silicon (100) and transform the top portion into an ultra-thin flexible silicon fabric with prefabricated devices, preserving ultra-large-scale-integration density and same device performance. This can be done in a cost effective manner due to its full compatibility with standard CMOS processes. In this paper, using the same approach, for the first time we demonstrate a ferroelectric random access memory (FeRAM) cell on flexible silicon fabric platform and assess its functionality and practical potential.

  12. Charge selective contact on ultra-thin In(OH)xS y/Pb(OH) xS y heterostructure prepared by SILAR

    International Nuclear Information System (INIS)

    Gavrilov, S.; Oja, I.; Lim, B.; Belaidi, A.; Bohne, W.; Strub, E.; Roehrich, J.; Lux-Steiner, M.-Ch.; Dittrich, Th.

    2006-01-01

    Ultra-thin In(OH) x S y /Pb(OH) x S y heterostructures were formed by the wet chemical SILAR (successive ion layer adsorption and reaction) technique. ERDA (elastic recoil detection analysis) was used for stoichiometry analysis. The heterocontacts were conditioned by joint annealing of the two layers at different low temperatures in air. The charge selectivity was demonstrated with various small area solar cell structures. The results are discussed on the base of formation of bonds between sulphide clusters and passivation of defects with hydrogen containing species in hydroxy-sulphides. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. CMOS compatible fabrication of flexible and semi-transparent FeRAM on ultra-thin bulk monocrystalline silicon (100) fabric

    KAUST Repository

    Ghoneim, Mohamed T.

    2014-08-01

    Commercialization of flexible electronics requires reliable, high performance, ultra-compact and low power devices. To achieve them, we fabricate traditional electronics on bulk mono-crystalline silicon (100) and transform the top portion into an ultra-thin flexible silicon fabric with prefabricated devices, preserving ultra-large-scale-integration density and same device performance. This can be done in a cost effective manner due to its full compatibility with standard CMOS processes. In this paper, using the same approach, for the first time we demonstrate a ferroelectric random access memory (FeRAM) cell on flexible silicon fabric platform and assess its functionality and practical potential.

  14. Substrate effects on photoluminescence and low temperature phase transition of methylammonium lead iodide hybrid perovskite thin films

    Science.gov (United States)

    Shojaee, S. A.; Harriman, T. A.; Han, G. S.; Lee, J.-K.; Lucca, D. A.

    2017-07-01

    We examine the effects of substrates on the low temperature photoluminescence (PL) spectra and phase transition in methylammonium lead iodide hybrid perovskite (CH3NH3PbI3) thin films. Structural characterization at room temperature with X-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy indicated that while the chemical structure of films deposited on glass and quartz was similar, the glass substrate induced strain in the perovskite films and suppressed the grain growth. The luminescence response and phase transition of the perovskite thin films were studied by PL spectroscopy. The induced strain was found to affect both the room temperature and low temperature PL spectra of the hybrid perovskite films. In addition, it was found that the effects of the glass substrate inhibited a tetragonal to orthorhombic phase transition such that it occurred at lower temperatures.

  15. Understanding the role of ultra-thin polymeric interlayers in improving efficiency of polymer light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Bailey, Jim; Wang, Xuhua; Bradley, Donal D. C.; Kim, Ji-Seon, E-mail: ji-seon.kim@imperial.ac.uk [Department of Physics and Centre for Plastic Electronics, South Kensington Campus, Imperial College London, London SW7 2AZ (United Kingdom); Wright, Edward N.; Walker, Alison B. [Department of Physics, University of Bath, Bath BA2 7AY (United Kingdom)

    2014-05-28

    Insertion of ultra-thin polymeric interlayers (ILs) between the poly(3,4-ethylenedioxythiophene):polystyrene sulphonate hole injection and poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT) light emission layers of polymer light emitting diodes (PLEDs) can significantly increase their efficiency. In this paper, we investigate experimentally a broad range of probable causes of this enhancement with an eye to determining which IL parameters have the most significant effects. The importance of hole injection and electron blocking was studied through varying the IL material (and consequently its electronic energy levels) for both PLED and hole-only diode structures. The role of IL conductivity was examined by introducing a varying level of charge-transfer doping through blending the IL materials with a strong electron-accepting small molecule in concentrations from 1% to 7% by weight. Depositing ILs with thicknesses below the exciton diffusion length of ∼15 nm allowed the role of the IL as a physical barrier to exciton quenching to be probed. IL containing PLEDs was also fabricated with Lumation Green Series 1300 (LG 1300) light emission layers. On the other hand, the PLEDs were modeled using a 3D multi-particle Kinetic Monte Carlo simulation coupled with an optical model describing how light is extracted from the PLED. The model describes charge carrier transport and interactions between electrons, holes, singlets, and triplets, with the current density, luminance, and recombination zone (RZ) locations calculated for each PLED. The model shows F8BT PLEDs have a narrow charge RZ adjacent to the anode, while LG 1300 PLEDs have a wide charge RZ that is evenly distributed across the light emitting layer. Varying the light emitting layer from F8BT to Lumation Green Series 1300, we therefore experimentally examine the dependence of the IL function, specifically in regard to anode-side exciton quenching, on the location of the RZ. We found an exponential dependence of

  16. A novel ultra-thin 3D detector-For plasma diagnostics at JET and ITER tokamaks

    International Nuclear Information System (INIS)

    Garcia, Francisco; Pelligrini, G.; Balbuena, J.; Lozano, M.; Orava, R.; Ullan, M.

    2009-01-01

    A novel ultra-thin silicon detector called U3DTHIN has been designed and built for applications that range from Neutral Particle Analyzers (NPA) used in Corpuscular Diagnostics of High Temperature Plasma to very low X-ray spectroscopy. The main purpose of this detector is to provide a state-of-the-art solution to upgrade the current detector system of the NPAs at JET and also to pave the road for the future detection systems of the ITER experimental reactor. Currently the NPAs use a very thin scintillator-photomultiplier tube [F. Garcia, S.S. Kozlovsky, D.V. Balin, Background Properties of CEM, MCP and PMT detectors at n-γ irradiation. Preprint PNPI-2392, Gatchina, 2000, p. 9 ; F. Garcia, S.S. Kozlovsky, V.V. Ianovsky, Scintillation Detectors with Low Sensitivity to n-γ Background. Preprint PNPI-2391, Gatchina, 2000, p. 8 ], and their main drawbacks are poor energy resolution, intrinsic scintillator nonlinearity, and relative low count rate capability and finally poor signal-to-background discrimination for the low-energy channels. The proposed new U3DTHIN detector is based on very thin sensitive substrate, which will provide nearly 100% detection efficiency for ions and at the same time very low sensitivity for neutron and gamma backgrounds. To achieve a very fast collection of the charge carriers generated by the incident ions, a 3D electrode structure [S. Parker, C. Kenney, J. Segal, Nucl. Instr. and Meth. A 395 (1997) 328 ; G. Pellegrini, P. Roy, A. Al-Ajili, R. Bates, L. Haddad, M. Horn, K. Mathieson, J. Melone, V. O'Shea, K.M. Smith, Nucl. Instr. and Meth. A 487 (2002) 19 ] has been introduced in the sensitive volume of the detector. The geometry of the electrode is known to be rad-hard. One of the most innovative features of these detectors is the optimal combination of the thin entrance window and the sensitive substrate thickness, which allows a very large dynamic range for ion detection. GEANT4 simulations were performed to find the losses of energy in

  17. Hybrid thin films based on bilayer heterojunction of titania nanocrystals/polypyrrole/natural dyes (Kappaphycus alvarezii) materials

    Science.gov (United States)

    Ghazali, Salmah Mohd; Salleh, Hasiah; Dagang, Ahmad Nazri; Ghazali, Mohd Sabri Mohd; Ali, Nik Aziz Nik; Rashid, Norlaily Abdul; Kamarulzaman, Nurul Huda; Ahmad, Wan Almaz Dhafina Che Wan

    2017-09-01

    In this research, hybrid thin films which consist of a combination of organic red seaweed (RS) (Kappaphycus alvarezii) and polypyrrole (PPy) with inorganic titania nanocrystals (TiO2 NCs) materials were fabricated. These hybrid thin films were fabricated accordingly with bilayer heterojunction of ITO/TiO2 NCs/PPy/RS via electrochemical method using Electrochemical Impedance Spectroscopy (EIS). The effect of number of scans (thickness) of titania on optical and electrical properties of hybrid thin films were studied. TiO2 NCs function as an electron acceptor and electronic conductor. Meanwhile, PPy acts as holes conductor and RS dye acts as a photosensitizer enhances the optical and electrical properties of the thin films. The UV absorption spectrum of TiO2 NCs, PPy and RS are characterized by UV-Visible spectroscopy, while the functional group of RS was characterized by Fourier transform infrared spectroscopy (FTIR). The UV-Vis spectra showed that TiO2 NCs, PPy and RS were absorbed over a wide range of light spectrum which were 200-300 nm, 300-900 nm and 250-900 nm; respectively. The FTIR spectra of the RS showed the presence of hydroxyl group which was responsible for a good sensitizer for these hybrid solar cells. The electrical conductivity of these hybrid thin films were measured by using four point probes. The electrical conductivity of ITO/ (1)TiO2 NCs/PPy/RS thin film under the radiation of 100 Wm-2 was 0.062 Scm-1, hence this hybrid thin films can be applied in solar cell application.

  18. A Review on the Low-Dimensional and Hybridized Nanostructured Diamond Films

    Directory of Open Access Journals (Sweden)

    Hongdong Li

    2015-01-01

    Full Text Available In the last decade, besides the breakthrough of high-rate growth of chemical vapor deposited single-crystal diamonds, numerous nanostructured diamond films have been rapidly developed in the research fields of the diamond-based sciences and industrial applications. The low-dimensional diamonds of two-dimensional atomic-thick nanofilms and nanostructural diamond on the surface of bulk diamond films have been theoretically and experimentally investigated. In addition, the diamond-related hybrid nanostructures of n-type oxide/p-type diamond and n-type nitride/p-type diamond, having high performance physical and chemical properties, are proposed for further applications. In this review, we first briefly introduce the three categories of diamond nanostructures and then outline the current advances in these topics, including their design, fabrication, characterization, and properties. Finally, we address the remaining challenges in the research field and the future activities.

  19. Andreev reflexion studies on planar hybrid SNS-junctions based on 122-thin films

    Energy Technology Data Exchange (ETDEWEB)

    Doering, Sebastian; Schmidt, Stefan; Schmidl, Frank; Tympel, Volker; Seidel, Paul [Friedrich-Schiller-Universitaet Jena, Institut fuer Festkoerperphysik, Helmholtzweg 5, Jena (Germany); Haindl, Silvia; Kurth, Fritz; Iida, Kazumasa; Holzapfel, Bernhard [IFW Dresden, Institut fuer Metallische Werkstoffe, 01069 Dresden (Germany)

    2012-07-01

    To investigate the properties of iron-based superconductors, we prepared hybrid junctions in thin film technique. Therefore two geometries were prepared, a planar SNS-junction and an edge junction. The base electrode was made of Ba(Fe{sub 0.9}Co{sub 0.1}){sub 2}As{sub 2} thin films, a sputtered gold layer acts as normal barrier for the planar junction and for the counter electrode we used the conventional superconductor lead. We measured the electrical properties of each electrode, as well as the junctions itself. To obtain information about the order parameter symmetry, we show the differential conductance and compare with different variations of an extended BTK-model. We show differences and commonalities between the results of both junction geometries.

  20. Disorder Improves Light Absorption in Thin Film Silicon Solar Cells with Hybrid Light Trapping Structure

    Directory of Open Access Journals (Sweden)

    Yanpeng Shi

    2016-01-01

    Full Text Available We present a systematic simulation study on the impact of disorder in thin film silicon solar cells with hybrid light trapping structure. For the periodical structures introducing certain randomness in some parameters, the nanophotonic light trapping effect is demonstrated to be superior to their periodic counterparts. The nanophotonic light trapping effect can be associated with the increased modes induced by the structural disorders. Our study is a systematic proof that certain disorder is conceptually an advantage for nanophotonic light trapping concepts in thin film solar cells. The result is relevant to the large field of research on nanophotonic light trapping which currently investigates and prototypes a number of new concepts including disordered periodic and quasiperiodic textures. The random effect on the shape of the pattern (position, height, and radius investigated in this paper could be a good approach to estimate the influence of experimental inaccuracies for periodic or quasi-periodic structures.

  1. The Effect of Drawing Ratio on Mechanical Property of Nano-Hybrid Polyimide Composite Films

    Directory of Open Access Journals (Sweden)

    CHEN Hao

    2017-06-01

    Full Text Available In order to investigate the impact of drawing ratio of inorganic nano-hybrid polyamide three-layer composite films,the stretched composite films with different draw ratio were prepared by drawing partial imido polyamide film and then through the ring closing reaction in the high temperature,and the draw ratio was 0% ,2% , 4% ,6% ,8% ,10% ,12% ,14% etc. Under the same conditions,we made different draw ratio of three-layer composite film tensile test with the electronic universal material testing machine. The results show: doped inorganic nanometer oxide made PI film elastic modulus increase slightly,the tensile strength and elongation at break decrease obviously,but the nano hybrid three-layer composite PI films still had good mechanical properties; The yield of polyimide film should be caused by forced high-elastic deformation of polyimide molecular chain,and it had nothing to do with whether doped inorganic nano-oxide or whether through stretched processing; With the increase of draw ratio,the elastic modulus of the nano hybrid three-layer composite PI films existed the trend of first increased and then slow down gradually,and the tensile strength and elongation at break first decreased and then increased.

  2. Influence of Surface Passivation on AlN Barrier Stress and Scattering Mechanism in Ultra-thin AlN/GaN Heterostructure Field-Effect Transistors.

    Science.gov (United States)

    Lv, Y J; Song, X B; Wang, Y G; Fang, Y L; Feng, Z H

    2016-12-01

    Ultra-thin AlN/GaN heterostructure field-effect transistors (HFETs) with, and without, SiN passivation were fabricated by the same growth and device processes. Based on the measured DC characteristics, including the capacitance-voltage (C-V) and output current-voltage (I-V) curves, the variation of electron mobility with gate bias was found to be quite different for devices with, and without, SiN passivation. Although the AlN barrier layer is ultra thin (c. 3 nm), it was proved that SiN passivation induces no additional tensile stress and has no significant influence on the piezoelectric polarization of the AlN layer using Hall and Raman measurements. The SiN passivation was found to affect the surface properties, thereby increasing the electron density of the two-dimensional electron gas (2DEG) under the access region. The higher electron density in the access region after SiN passivation enhanced the electrostatic screening for the non-uniform distributed polarization charges, meaning that the polarization Coulomb field scattering has a weaker effect on the electron drift mobility in AlN/GaN-based devices.

  3. Tuning of Rashba/Dresselhaus Spin Splittings by Inserting Ultra-Thin InAs Layers at Interfaces in Insulating GaAs/AlGaAs Quantum Wells.

    Science.gov (United States)

    Yu, Jinling; Zeng, Xiaolin; Cheng, Shuying; Chen, Yonghai; Liu, Yu; Lai, Yunfeng; Zheng, Qiao; Ren, Jun

    2016-12-01

    The ratio of Rashba and Dresselhaus spin splittings of the (001)-grown GaAs/AlGaAs quantum wells (QWs), investigated by the spin photocurrent spectra induced by circular photogalvanic effect (CPGE) at inter-band excitation, has been effectively tuned by changing the well width of QWs and by inserting a one-monolayer-thick InAs layer at interfaces of GaAs/AlGaAs QWs. Reflectance difference spectroscopy (RDS) is also employed to study the interface asymmetry of the QWs, whose results are in good agreement with that obtained by CPGE measurements. It is demonstrated that the inserted ultra-thin InAs layers will not only introduce structure inversion asymmetry (SIA), but also result in additional interface inversion asymmetry (IIA), whose effect is much stronger in QWs with smaller well width. It is also found that the inserted InAs layer brings in larger SIA than IIA. The origins of the additional SIA and IIA introduced by the inserted ultra-thin InAs layer have been discussed.

  4. Using an ultra-thin non-doped orange emission layer to realize high efficiency white organic light-emitting diodes with low efficiency roll-off

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Liping; Chen, Jiangshan; Ma, Dongge, E-mail: mdg1014@ciac.ac.cn [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Graduate University of the Chinese Academy of Sciences, Changchun 130022 (China); Zhao, Yongbiao [Luminous Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore); Zhang, Hongmei [Department of Materials Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023 (China)

    2014-06-28

    By adopting an ultra-thin non-doped orange emission layer sandwiched between two blue emission layers, high efficiency white organic light-emitting diodes (WOLEDs) with reduced efficiency roll-off were fabricated. The optimized devices show a balanced white emission with Internationale de L'Eclairage of (0.41, 0.44) at the luminance of 1000 cd/m{sup 2}, and the maximum power efficiency, current efficiency (CE), and external quantum efficiency reach 63.2 lm/W, 59.3 cd/A, and 23.1%, which slightly shift to 53.4 lm/W, 57.1 cd/A, and 22.2% at 1000 cd/m{sup 2}, respectively, showing low efficiency roll-off. Detailed investigations on the recombination zone and the transient electroluminescence (EL) clearly reveal the EL processes of the ultra-thin non-doped orange emission layer in WOLEDs.

  5. Hybrid chitosan–Pluronic F-127 films with BaTiO3:Co nanoparticles: Synthesis and properties

    International Nuclear Information System (INIS)

    Fuentes, S.; Dubo, J.; Barraza, N.; González, R.; Veloso, E.

    2015-01-01

    In this study, magnetic BaTiO 3 :Co (BT:Co) nanoparticles prepared using a combined sol–gel–hydrothermal technique were dispersed in a chitosan/Pluronic F-127 solution (QO/Pl) to obtain a nanocomposite hybrid films. Nanoparticles and hybrid films were characterized by X-ray powder diffraction, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and alternating gradient magnetometry (AGM). Experimental results indicated that the BT:Co nanoparticles were encapsulated in the QO/Pl hybrid films and that the magnetic properties of the QO/Pl/BT:Co nanocomposites are similar to the naked BT:Co nanoparticles. Results indicate that Co doping produces an enhancement in the ferromagnetic behavior of the BT nanoparticle. The coating restricts this enhancement only to low-fields, leaving the diamagnetic behavior of BT at high-fields. Magnetically stable sizes (PSD) were obtained at 3% Co doping for both naked nanoparticles and hybrid films. These show an increased magnetic memory capacity and a softer magnetic hardness with respect to non-doped BT nanoparticles. - Highlights: • We described the synthesis of magnetic BaTiO 3 :Co dispersed in chitosan (QO)/Pluronic F-127 (Pl) solution by sonication to obtain nanocomposite hybrid films. • We describe the physical and magnetic properties of BaTiO 3 :Co nanoparticles and QO/Pl/BT:Co hybrid films. • The magnetic properties are defines by the presence of magnetic domains. These magnetic domains are close related with the amount of Co in the host lattice. • The prepared phases could be considered as multifunctional materials, with magnetic and ferri-electrical properties, with potential uses in the design of devices

  6. Hybrid chitosan–Pluronic F-127 films with BaTiO{sub 3}:Co nanoparticles: Synthesis and properties

    Energy Technology Data Exchange (ETDEWEB)

    Fuentes, S., E-mail: sfuentes@ucn.cl [Departamento de Ciencias Farmacéuticas, Facultad de Ciencias, Universidad Católica del Norte, Casilla 1280, Antofagasta (Chile); Center for the Development of Nanoscience and Nanotechnology, CEDENNA, Santiago (Chile); Dubo, J. [Departamento de Ciencias Farmacéuticas, Facultad de Ciencias, Universidad Católica del Norte, Casilla 1280, Antofagasta (Chile); Barraza, N. [Departamento de Física, Facultad de Ciencias, Universidad Católica del Norte, Casilla 1280, Antofagasta (Chile); González, R. [Laboratorio de Magnetismo, Departamento de Ciencias Geológicas, Universidad Católica del Norte, Antofagasta (Chile); Veloso, E. [Dirección de Investigaciones Científicas y Tecnológicas, Pontificia Universidad Católica de Chile, Avenida Vicuña Mackenna 4860, Santiago (Chile)

    2015-03-01

    In this study, magnetic BaTiO{sub 3}:Co (BT:Co) nanoparticles prepared using a combined sol–gel–hydrothermal technique were dispersed in a chitosan/Pluronic F-127 solution (QO/Pl) to obtain a nanocomposite hybrid films. Nanoparticles and hybrid films were characterized by X-ray powder diffraction, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and alternating gradient magnetometry (AGM). Experimental results indicated that the BT:Co nanoparticles were encapsulated in the QO/Pl hybrid films and that the magnetic properties of the QO/Pl/BT:Co nanocomposites are similar to the naked BT:Co nanoparticles. Results indicate that Co doping produces an enhancement in the ferromagnetic behavior of the BT nanoparticle. The coating restricts this enhancement only to low-fields, leaving the diamagnetic behavior of BT at high-fields. Magnetically stable sizes (PSD) were obtained at 3% Co doping for both naked nanoparticles and hybrid films. These show an increased magnetic memory capacity and a softer magnetic hardness with respect to non-doped BT nanoparticles. - Highlights: • We described the synthesis of magnetic BaTiO{sub 3}:Co dispersed in chitosan (QO)/Pluronic F-127 (Pl) solution by sonication to obtain nanocomposite hybrid films. • We describe the physical and magnetic properties of BaTiO{sub 3}:Co nanoparticles and QO/Pl/BT:Co hybrid films. • The magnetic properties are defines by the presence of magnetic domains. These magnetic domains are close related with the amount of Co in the host lattice. • The prepared phases could be considered as multifunctional materials, with magnetic and ferri-electrical properties, with potential uses in the design of devices.

  7. Enhancement of TE polarized light extraction efficiency in nanoscale (AlN)m /(GaN)n (m>n) superlattice substitution for Al-rich AlGaN disorder alloy: ultra-thin GaN layer modulation

    International Nuclear Information System (INIS)

    Jiang, Xin-he; Shi, Jun-jie; Zhong, Hong-xia; Huang, Pu; Ding, Yi-min; Yu, Tong-jun; Shen, Bo; Lu, Jing; Zhang, Min; Wang, Xihua

    2014-01-01

    The problem of achieving high light extraction efficiency in Al-rich Al x Ga 1−x N is of paramount importance for the realization of AlGaN-based deep ultraviolet (DUV) optoelectronic devices. To solve this problem, we investigate the microscopic mechanism of valence band inversion and light polarization, a crucial factor for enhancing light extraction efficiency, in Al-rich Al x Ga 1−x N alloy using the Heyd–Scuseria–Ernzerhof hybrid functional, local-density approximation with 1/2 occupation, and the Perdew–Burke–Ernzerhof functional, in which the spin–orbit coupling effect is included. We find that the microscopic Ga-atom distribution can effectively modulate the valence band structure of Al-rich Al x Ga 1−x N. Moreover, we prove that the valence band arrangement in the decreasing order of heavy hole, light hole, and crystal-field split-off hole can be realized by using nanoscale (AlN) m /(GaN) n (m>n) superlattice (SL) substituting for Al-rich Al x Ga 1−x N disorder alloy as the active layer of optoelectronic devices due to the ultra-thin GaN layer modulation. The valence band maximum, i.e., the heavy hole band, has p x - and p y -like characteristics and is highly localized in the SL structure, which leads to the desired transverse electric (TE) polarized (E⊥c) light emission with improved light extraction efficiency in the DUV spectral region. Some important band-structure parameters and electron/hole effective masses are also given. The physical origin for the valence band inversion and TE polarization in (AlN) m /(GaN) n SL is analyzed in depth. (paper)

  8. Few-Layer MoS2-Organic Thin-Film Hybrid Complementary Inverter Pixel Fabricated on a Glass Substrate.

    Science.gov (United States)

    Lee, Hee Sung; Shin, Jae Min; Jeon, Pyo Jin; Lee, Junyeong; Kim, Jin Sung; Hwang, Hyun Chul; Park, Eunyoung; Yoon, Woojin; Ju, Sang-Yong; Im, Seongil

    2015-05-13

    Few-layer MoS2-organic thin-film hybrid complementary inverters demonstrate a great deal of device performance with a decent voltage gain of ≈12, a few hundred pW power consumption, and 480 Hz switching speed. As fabricated on glass, this hybrid CMOS inverter operates as a light-detecting pixel as well, using a thin MoS2 channel. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. ZnO nanostructures as electron extraction layers for hybrid perovskite thin films

    Science.gov (United States)

    Nikolaidou, Katerina; Sarang, Som; Tung, Vincent; Lu, Jennifer; Ghosh, Sayantani

    Optimum interaction between light harvesting media and electron transport layers is critical for the efficient operation of photovoltaic devices. In this work, ZnO layers of different morphologies are implemented as electron extraction and transport layers for hybrid perovskite CH3NH3PbI3 thin films. These include nanowires, nanoparticles, and single crystalline film. Charge transfer at the ZnO/perovskite interface is investigated and compared through ultra-fast characterization techniques, including temperature and power dependent spectroscopy, and time-resolved photoluminescence. The nanowires cause an enhancement in perovskite emission, which may be attributed to increased scattering and grain boundary formation. However, the ZnO layers with decreasing surface roughness exhibit better electron extraction, as inferred from photoluminescence quenching, reduction in the number of bound excitons, and reduced exciton lifetime in CH3NH3PbI3 samples. This systematic study is expected to provide an understanding of the fundamental processes occurring at the ZnO-CH3NH3PbI3 interface and ultimately, provide guidelines for the ideal configuration of ZnO-based hybrid Perovskite devices. This research was supported by National Aeronautics and Space administration (NASA) Grant No: NNX15AQ01A.

  10. Dendritic Ni(Cu)-polypyrrole hybrid films for a pseudo-capacitor.

    Science.gov (United States)

    Choi, Bit Na; Chun, Woo Won; Qian, Aniu; Lee, So Jeong; Chung, Chan-Hwa

    2015-11-28

    Dendritic Ni(Cu)-polypyrrole hybrid films are fabricated for a pseudo-capacitor in a unique morphology using two simple methods: electro-deposition and electrochemical de-alloying. Three-dimensional structures of porous dendrites are prepared by electro-deposition within the hydrogen evolution reaction (HER) at a high cathodic potential; the high-surface-area structure provides sufficient redox reactions between the electrodes and the electrolyte. The dependence of the active-layer thickness on the super-capacitor performance is also investigated, and the 60 μm-thick Ni(Cu)PPy hybrid electrode presents the highest performance of 659.52 F g(-1) at the scan rate of 5 mV s(-1). In the thicker layers, the specific capacitance became smaller due to the diffusion limitation of the ions in an electrolyte. The polypyrrole-hybridization on the porous dendritic Ni(Cu) electrode provides superior specific capacitance and excellent cycling stability due to the improvement in electric conductivity by the addition of conducting polypyrrole in the matrices of the dendritic nano-porous Ni(Cu) layer and the synergistic effect of composite materials.

  11. Hybrid phototransistors based on bulk heterojunction films of poly(3-hexylthiophene) and zinc oxide nanoparticle.

    Science.gov (United States)

    Nam, Sungho; Seo, Jooyeok; Park, Soohyeong; Lee, Sooyong; Jeong, Jaehoon; Lee, Hyena; Kim, Hwajeong; Kim, Youngkyoo

    2013-02-01

    Hybrid phototransistors (HPTRs) were fabricated on glass substrates using organic/inorganic hybrid bulk heterojunction films of p-type poly(3-hexylthiophene) (P3HT) and n-type zinc oxide nanoparticles (ZnO(NP)). The content of ZnO(NP) was varied up to 50 wt % in order to understand the composition effect of ZnO(NP) on the performance of HPTRs. The morphology and nanostructure of the P3HT:ZnO(NP) films was examined by employing high resolution electron microscopes and synchrotron radiation grazing angle X-ray diffraction system. The incident light intensity (P(IN)) was varied up to 43.6 μW/cm², whereas three major wavelengths (525 nm, 555 nm, 605 nm) corresponded to the optical absorption of P3HT were applied. Results showed that the present HPTRs showed typical p-type transistor performance even though the n-type ZnO(NP) content increased up to 50 wt %. The highest transistor performance was obtained at 50 wt %, whereas the lowest performance was measured at 23 wt % because of the immature bulk heterojunction morphology. The drain current (I(D)) was proportionally increased with P(IN) due to the photocurrent generation in addition to the field-effect current. The highest apparent and corrected responsivities (R(A) = 4.7 A/W and R(C) = 2.07 A/W) were achieved for the HPTR with the P3HT:ZnO(NP) film (50 wt % ZnO(NP)) at P(IN) = 0.27 μW/cm² (555 nm).

  12. Synthesis and electrical characterization of low-temperature thermal-cured epoxy resin/functionalized silica hybrid-thin films for application as gate dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Na, Moonkyong, E-mail: nmk@keri.re.kr [HVDC Research Division, Korea Electrotechnology Research Institute, Changwon, 642-120 (Korea, Republic of); System on Chip Chemical Process Research Center, Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 790-784 (Korea, Republic of); Kang, Young Taec [Creative and Fundamental Research Division, Korea Electrotechnology Research Institute, Changwon, 642-120 (Korea, Republic of); Department of Polymer Science and Engineering, Pusan National University, Busan, 609-735 (Korea, Republic of); Kim, Sang Cheol [HVDC Research Division, Korea Electrotechnology Research Institute, Changwon, 642-120 (Korea, Republic of); Kim, Eun Dong [Creative and Fundamental Research Division, Korea Electrotechnology Research Institute, Changwon, 642-120 (Korea, Republic of)

    2013-07-31

    Thermal-cured hybrid materials were synthesized from homogenous hybrid sols of epoxy resins and organoalkoxysilane-functionalized silica. The chemical structures of raw materials and obtained hybrid materials were characterized using Fourier transform infrared spectroscopy. The thermal resistance of the hybrids was enhanced by hybridization. The interaction between epoxy matrix and the silica particles, which caused hydrogen bonding and van der Waals force was strengthened by organoalkoxysilane. The degradation temperature of the hybrids was improved by approximately 30 °C over that of the parent epoxy material. The hybrid materials were formed into uniformly coated thin films of about 50 nm-thick using a spin coater. An optimum mixing ratio was used to form smooth-surfaced hybrid films. The electrical property of the hybrid film was characterized, and the leakage current was found to be well below 10{sup −6} A cm{sup −2}. - Highlights: • Preparation of thermal-curable hybrid materials using epoxy resin and silica. • The thermal stability was enhanced through hybridization. • The insulation property of hybrid film was investigated as gate dielectrics.

  13. The Effect of Drawing Ratio on Mechanical Property of Nano-Hybrid Polyimide Composite Films

    OpenAIRE

    CHEN Hao; YANG Rui-xiao; WU Chuan-gang; FAN Yong

    2017-01-01

    In order to investigate the impact of drawing ratio of inorganic nano-hybrid polyamide three-layer composite films,the stretched composite films with different draw ratio were prepared by drawing partial imido polyamide film and then through the ring closing reaction in the high temperature,and the draw ratio was 0% ,2% , 4% ,6% ,8% ,10% ,12% ,14% etc. Under the same conditions,we made different draw ratio of three-layer composite film tensile test with the electronic universal material testi...

  14. Nano-Protrusive Gold Nanoparticle-Hybridized Polymer Thin Film as a Sensitive, Multipatternable, and Antifouling Biosensor Platform.

    Science.gov (United States)

    Lee, Jeong-Hoon; Park, Byung-Soo; Ghang, Hyun-Gu; Song, Hyunjoon; Yang, Sung Yun

    2018-04-25

    Hybrid films consisting of anisotropic octahedral gold nanoparticles (AuNPs) and polymers had their surfaces functionalized and were immobilized on surface plasmon resonance (SPR) sensors for biomolecule detection. Specifically, carboxylated octahedral AuNPs (C-Oh-AuNPs) and poly(allylamine hydrochloride) (PAH) were assembled as ultrathin films by using a layer-by-layer process. The ionic strength generated from the functional groups of C-Oh-AuNP and PAH influenced the composition, its surface morphology, and the reactivity of the film toward further chemical reactions such as the synthesis of spherical AuNPs (S-AuNPs). We were thus able to control the size and the structure of the C-Oh-AuNP and S-AuNPs converted to nano-raspberry-shaped particles. This hierarchical AuNP hybrid film exhibits much more sensitive and stable detection of biomolecules than regular flat chip systems, and this result may be due to the SPR of the AuNP at its surface being able to markedly enhance the local optical field of the chip. The micropatterning of the hybrid coating was also studied by using a soft lithographic patterning method. We, in particular, worked on creating multiplex patterns having different combinations of shapes and fluorescent colors. We expect our hybrid coating system with multicode biomolecular arrays to be used as a powerful platform for biosensor applications.

  15. A thin-film silicon/silicon hetero-junction hybrid solar cell for photoelectrochemical water-reduction applications

    NARCIS (Netherlands)

    Vasudevan, R.A.; Thanawala, Z; Han, L.; Buijs, Thom; Tan, H.; Deligiannis, D.; Perez Rodriguez, P.; Digdaya, I.A.; Smith, W.A.; Zeman, M.; Smets, A.H.M.

    2016-01-01

    A hybrid tandem solar cell consisting of a thin-film, nanocrystalline silicon top junction and a siliconheterojunction bottom junction is proposed as a supporting solar cell for photoelectrochemical applications.Tunneling recombination junction engineering is shown to be an important consideration

  16. Plasma assisted fabrication of multi-layer graphene/nickel hybrid film as enhanced micro-supercapacitor electrodes

    Science.gov (United States)

    Ding, Q.; Li, W. L.; Zhao, W. L.; Wang, J. Y.; Xing, Y. P.; Li, X.; Xue, T.; Qi, W.; Zhang, K. L.; Yang, Z. C.; Zhao, J. S.

    2017-03-01

    A facile synthesis strategy has been developed for fabricating multi-layer graphene/nickel hybrid film as micro-supercapacitor electrodes by using plasma enhanced chemical vapor deposition. The as-presented method is advantageous for rapid graphene growth at relatively low temperature of 650 °C. In addition, after pre-treating for the as-deposited nickel film by using argon plasma bombardment, the surface-to-volume ratio of graphene film on the treated nickel substrate is effectively increased by the increasing of surface roughness. This is demonstrated by the characterization results from transmission electron microscopy, scanning electron microscope and atomic force microscopy. Moreover, the electrochemical performance of the resultant graphene/nickel hybrid film as micro-supercapacitor working electrode was investigated by cyclic voltammetry and galvanostatic charge/discharge measurements. It was found that the increase of the surface-to-volume ratio of graphene/nickel hybrid film improved the specific capacitance of 10 times as the working electrode of micro-supercapacitor. Finally, by using comb columnar shadow mask pattern, the micro-supercapacitor full cell device was fabricated. The electrochemical performance measurements of the micro-supercapacitor devices indicate that the method presented in this study provides an effective way to fabricate micro-supercapacitor device with enhanced energy storage property.

  17. Enhanced electrocatalytic activity of reduced graphene oxide-Os nanoparticle hybrid films obtained at a liquid/liquid interface

    Science.gov (United States)

    Bramhaiah, K.; Pandey, Indu; Singh, Vidya N.; Kavitha, C.; John, Neena S.

    2018-03-01

    Hybrid films of reduced graphene oxide-osmium nanoparticles (rGO-Os NPs) synthesized at a liquid/liquid interface are explored for their electrocatalytic activity towards the oxidation of rhodamine B (RhB), a popular colourant found in textile industry effluents and a non-permitted food colour. The free-standing nature of the films enables them to be lifted directly on to electrodes without the aid of any binders. The films consist of aggregates of ultra-small Os NPs interspersed with rGO layers. The hybrid film exhibits enhanced RhB oxidation when compared to its constituents arising from the synergic effect between rGO and Os NPs, Os contributing to electrocatalysis and rGO contributing to high surface area and conductance as well as stabilization of Os nanoparticles. The electrochemical sensor based on rGO-Os NP hybrid film on pencil graphite electrode shows a remarkable performance for the quantitative detection of RhB with a linear variation in a wide range of concentrations, 4-1300 ppb (8.3 nM-2.71 μM). The modified electrode presents good stability over more than 6 months, reproducibility and anti-interference capability. The use of developed sensor for adequate detection of RhB in real samples such as food samples and pen markers is also demonstrated.

  18. Vortex pinning landscape in YBa2Cu3O7 films grown by hybrid liquid phase epitaxy

    International Nuclear Information System (INIS)

    Maiorov, B; Kursumovic, A; Stan, L; Zhou, H; Wang, H; Civale, L; Feenstra, R; MacManus-Driscoll, J L

    2007-01-01

    The influence of film thickness and growth rate on the vortex pinning in hybrid liquid phase epitaxy (HLPE) films was explored. Film growth rates as high as 12 nm s -1 (0.7 μm min -1 ) produced high J c films. Weak or no thickness dependence was found in films of thickness ranging from 0.4 to 3 μm. Field and angular measurements of the critical current density (J c ) and the power-law exponent (N) of the current-voltage curves were used to determine the nature of pinning. Films thinner than 0.6 μm showed a higher density of correlated defects parallel to the ab plane than thicker films. Using HLPE, it was possible to achieve very strong pinning in films ∼3 μm thick, yielding critical currents over 300 A cm -1 width at self-field, and as high as 35 A cm -1 width at μ 0 H = 3 T at T = 75.5 K. Decreasing the deposition rate allowed improving the high field performance, opening up the possibility to engineer the pinning landscape of the HLPE films

  19. Experimental validation of an ultra-thin metasurface cloak for hiding a metallic obstacle from an antenna radiation at low frequencies

    Science.gov (United States)

    Teperik, Tatiana V.; Burokur, Shah Nawaz; de Lustrac, André; Sabanowski, Guy; Piau, Gérard-Pascal

    2017-07-01

    We demonstrate numerically and experimentally an ultra-thin (≈ λ/240) metasurface-based invisibility cloak for low frequency antenna applications. We consider a monopole antenna mounted on a ground plane and a cylindrical metallic obstacle of diameter smaller than the wavelength located in its near-field. To restore the intrinsic radiation patterns of the antenna perturbed by this obstacle, a metasurface cloak consisting simply of a metallic patch printed on a dielectric substrate is wrapped around the obstacle. Using a finite element method based commercial electromagnetic solver, we show that the radiation patterns of the monopole antenna can be restored completely owing to electromagnetic modes of the resonant cavity formed between the patch and obstacle. The metasurface cloak is fabricated, and the concept is experimentally demonstrated at 125 MHz. Performed measurements are in good agreement with numerical simulations, verifying the efficiency of the proposed cloak.

  20. ANALYSIS ON THE BEHAVIOR OF PRECIPITATES IN ULTRA-THIN HOT STRIP OF PLAIN LOW CARBON STEEL PRODUCED BY COMPACT STRIP PRODUCTION

    Institute of Scientific and Technical Information of China (English)

    H. Yu; Y.L. Kang; H.B. Dong; D.L. Liu; J. Fu

    2002-01-01

    This paper investigated the mechanism of precipitation and its influence upon prop-erties of ultra-thin hot strips of low carbon steel produced by CSP techniques usingexperiment and thermodynamics theory. The experimental results show that thereare lots of fine and dispersive precipitates in microstructures. By analysis, most ofaluminum nitrides are in grains, while coexisted precipitates of MnS are along grainboundaries. Coexisted precipitates compose cation-vacancy type oxides such as Al2O3in the core, while MnS is at the fringe of surface. The precipitation behavior of AlNand MnS in the hot strip is studied by thermodynamic calculation. At last, implica-tions between strengthening effect and techniques are analyzed using obtained solubilityproducts.

  1. Metal-organic chemical vapor deposition of ultra-thin photovoltaic devices using a pyrite based p-i-n structure

    Energy Technology Data Exchange (ETDEWEB)

    Clayton, A.J., E-mail: andy.clayton@optictechnium.com [CSER, Glyndwr University, OpTIC Technium, St Asaph, LL17 0JD (United Kingdom); Irvine, S.J.C.; Barrioz, V.; Brooks, W.S.M. [CSER, Glyndwr University, OpTIC Technium, St Asaph, LL17 0JD (United Kingdom); Zoppi, G.; Forbes, I. [NPAC, Northumbria University, Newcastle upon Tyne, NE1 8ST (United Kingdom); Rogers, K.D.; Lane, D.W.; Hutchings, K.; Roncallo, S. [Centre for Material Science and Engineering, Cranfield University, Swindon, SN6 8LA (United Kingdom)

    2011-08-31

    Ultra-thin photovoltaic (PV) devices were produced by atmospheric pressure metal organic chemical vapour deposition (AP-MOCVD) incorporating a highly absorbing intermediate sulphurised FeS{sub x} layer into a CdS/CdTe structure. X-ray diffraction (XRD) confirmed a transitional phase change to pyrite FeS{sub 2} after post growth sulphur (S) annealing of the FeS{sub x} layer between 400 deg. C and 500 deg. C. Devices using a superstrate configuration incorporating a sulphurised or non-sulphurised FeS{sub x} layer were compared to p-n devices with only a CdS/CdTe structure. Devices with sulphurised FeS{sub x} layers performed least efficiently, even though pyrite fractions were present. Rutherford back scattering (RBS) confirmed deterioration of the CdS/FeS{sub x} interface due to S inter-diffusion during the annealing process.

  2. CO2 laser cutting of ultra thin (75 μm) glass based rigid optical solar reflector (OSR) for spacecraft application

    Science.gov (United States)

    Mishra, Shubham; Sridhara, N.; Mitra, Avijit; Yougandar, B.; Dash, Sarat Kumar; Agarwal, Sanjay; Dey, Arjun

    2017-03-01

    Present study reports for the first time laser cutting of multilayered coatings on both side of ultra thin (i.e., 75 μm) glass substrate based rigid optical solar reflector (OSR) for spacecraft thermal control application. The optimization of cutting parameters was carried out as a function of laser power, cutting speed and number of cutting passes and their effect on cutting edge quality. Systematic and in-detail microstructural characterizations were carried out by optical and scanning electron microscopy techniques to study the laser affected zone and cutting edge quality. Sheet resistance and water contact angle experiments were also conducted locally both prior and after laser cut to investigate the changes of electrical and surface properties, if any.

  3. A study on the optics of copper indium gallium (di)selenide (CIGS) solar cells with ultra-thin absorber layers.

    Science.gov (United States)

    Xu, Man; Wachters, Arthur J H; van Deelen, Joop; Mourad, Maurice C D; Buskens, Pascal J P

    2014-03-10

    We present a systematic study of the effect of variation of the zinc oxide (ZnO) and copper indium gallium (di)selenide (CIGS) layer thickness on the absorption characteristics of CIGS solar cells using a simulation program based on finite element method (FEM). We show that the absorption in the CIGS layer does not decrease monotonically with its layer thickness due to interference effects. Ergo, high precision is required in the CIGS production process, especially when using ultra-thin absorber layers, to accurately realize the required thickness of the ZnO, cadmium sulfide (CdS) and CIGS layer. We show that patterning the ZnO window layer can strongly suppress these interference effects allowing a higher tolerance in the production process.

  4. Optical investigation of atomic steps in ultra-thin InGaAs/InP quantum wells grown by vapor levitation epitaxy

    International Nuclear Information System (INIS)

    Morais, P.C.

    1988-09-01

    Ultra-thin InGaAs/InP single-quantum-well structures, grown by chloride transport vapor levitation epitaxy, have been investigated by low temperature photoluminescence (PL). Well resolved peaks are observed in the PL spectra which we attribute to monolayer (a/2=2.93 A) variations in quantum well (QW) thickness. Separate peak positions for QW thicknesses corresponding to 2-6 monolayers have been determined, providing an unambiguous thickness calibration for spectral shifts due to quantum confinement. The PL peak corresponding to two monolayers occurs at 1.314 eV corresponding to an energy shift of 524 meV. Experimental data agree very well with a simple effective-mass theory. (author) [pt

  5. Carbon nanotube-TiO{sub 2} hybrid films for detecting traces of O{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Llobet, E; Espinosa, E H; Sotter, E; Ionescu, R; Vilanova, X [MINOS, EMaS, Universitat Rovira i Virgili, 43007 Tarragona (Spain); Torres, J [Research Department, Carburos Metalicos, MATGAS, Campus UAB, 08193 Cerdanyola del Valles (Spain); Felten, A; Pireaux, J J [LISE, University of Namur, B-5000 Namur (Belgium); Ke, X; Tendeloo, G Van [EMAT, University of Antwerp, B-2020 Antwerp (Belgium); Renaux, F; Paint, Y; Hecq, M; Bittencourt, C [LCIA, University of Mons-Hainaut, B-7000, Mons (Belgium)

    2008-09-17

    Hybrid titania films have been prepared using an adapted sol-gel method for obtaining well-dispersed hydrogen plasma-treated multiwall carbon nanotubes in either pure titania or Nb-doped titania. The drop-coating method has been used to fabricate resistive oxygen sensors based on titania or on titania and carbon nanotube hybrids. Morphology and composition studies have revealed that the dispersion of low amounts of carbon nanotubes within the titania matrix does not significantly alter its crystallization behaviour. The gas sensitivity studies performed on the different samples have shown that the hybrid layers based on titania and carbon nanotubes possess an unprecedented responsiveness towards oxygen (i.e. more than four times higher than that shown by optimized Nb-doped TiO{sub 2} films). Furthermore, hybrid sensors containing carbon nanotubes respond at significantly lower operating temperatures than their non-hybrid counterparts. These new hybrid sensors show a strong potential for monitoring traces of oxygen (i.e. {<=}10 ppm) in a flow of CO{sub 2}, which is of interest for the beverage industry.

  6. Deposition and properties of Al-containing diamond-like carbon films by a hybrid ion beam sources

    International Nuclear Information System (INIS)

    Dai Wei; Wang Aiying

    2011-01-01

    Research highlights: → Weak carbide former, Al element, was incorporated into DLC films using a hybrid ion beams system comprising an anode-layer ion source and a magnetron sputtering unit. → The structure disorder of the films tended to decrease with Al atoms doping, which resulted in the distinct reduction of the film internal stress and hardness, but the internal stress dropped faster than the hardness. → The DLC films with low internal stress and high hardness can be acquired by Al incorporation. - Abstract: Metal incorporation is one of the most effective methods for relaxing internal stress in diamond-like carbon (DLC) films. It was reported that the chemical state of the incorporated metal atoms has a significant influence on the film internal stress. The doped atoms embedding in the DLC matrix without bonding with C atoms can reduce the structure disorder of the DLC films through bond angle distortion and thus relax the internal stress of the films. In present paper, Al atoms, which are inert to carbon, were incorporated into the DLC films deposited by a hybrid ion beams system comprising an anode-layer ion source and a magnetron sputtering unit. The film composition, microstructure and atomic bond structure were characterized using X-ray photoelectron spectroscopy, transmission electron microscopy and Raman spectroscopy. The internal stress, mechanical properties and tribogoical behavior were studied as a function of Al concentration using a stress-tester, nanoindentation and ball-on-disc tribo-tester, respectively. The results indicated that the incorporated Al atoms were dissolved in the DLC matrix without bonding with C atoms and the films exhibited the feature of amorphous carbon. The structure disorder of the films tended to decrease with Al atoms incorporation. This resulted in the distinct reduction of the internal stress in the films. All Al-DLC films exhibited a lower friction coefficient compared with pure DLC film. The formation of the

  7. Modification of metal–InGaAs Schottky barrier behaviour by atomic layer deposition of ultra-thin Al2O3 interlayers

    International Nuclear Information System (INIS)

    Chauhan, Lalit; Gupta, Suman; Jaiswal, Piyush; Bhat, Navakanta; Shivashankar, S.A.; Hughes, G.

    2015-01-01

    The effect of inserting ultra-thin atomic layer deposited Al 2 O 3 dielectric layers (1 nm and 2 nm thick) on the Schottky barrier behaviour for high (Pt) and low (Al) work function metals on n- and p-doped InGaAs substrates has been investigated. Rectifying behaviour was observed for the p-type substrates (both native oxide and sulphur passivated) for both the Al/p-InGaAs and Al/Al 2 O 3 /p-InGaAs contacts. The Pt contacts directly deposited on p-InGaAs displayed evidence of limited rectification which increased with Al 2 O 3 interlayer thickness. Ohmic contacts were formed for both metals on n-InGaAs in the absence of an Al 2 O 3 interlayer, regardless of surface passivation. However, limited rectifying behaviour was observed for both metals on the 2 nm Al 2 O 3 /n-InGaAs samples for the sulphur passivated InGaAs surface, indicating the importance of both surface passivation and the presence of an ultra-thin dielectric interlayer on the current–voltage characteristics displayed by these devices. - Highlights: • Investigation of the modification of metal–InGaAs Schottky barrier (SB) behaviour • Improving metal–InGaAs interface by sulphur passivation and ultrathin interlayer • Examine the effect of low work function and high work function metals on SB • Different SB behaviours observed on both n-type InGaAs and p-type InGaAs • Metal/n-InGaAs interface is more strongly pinned than the metal/p-InGaAs interface

  8. Advanced technique for ultra-thin residue inspection with sub-10nm thickness using high-energy back-scattered electrons

    Science.gov (United States)

    Han, Jin-Hee

    2018-03-01

    Recently the aspect ratio of capacitor and via hole of memory semiconductor device has been dramatically increasing in order to store more information in a limited area. A small amount of remained residues after etch process on the bottom of the high aspect ratio structure can make a critical failure in device operation. Back-scattered electrons (BSE) are mainly used for inspecting the defect located at the bottom of the high aspect ratio structure or analyzing the overlay of the multi-layer structure because these electrons have a high linearity with the direction of emission and a high kinetic energy above 50eV. However, there is a limitation on that it cannot detect ultra-thin residue material having a thickness of several nanometers because the surface sensitivity is extremely low. We studied the characteristics of BSE spectra using Monte Carlo simulations for several cases which the high aspect ratio structures have extreme microscopic residues. Based on the assumption that most of the electrons emitted without energy loss are localized on the surface, we selected the detection energy window which has a range of 20eV below the maximum energy of the BSE. This window section is named as the high-energy BSE region. As a result of comparing the detection sensitivity of the conventional and the high-energy BSE detection mode, we found that the detection sensitivity for the residuals which have 2nm thickness is improved by more than 10 times in the high-energy BSE mode. This BSE technology is a new inspection method that can greatly be improved the inspection sensitivity for the ultra-thin residual material presented in the high aspect ratio structure, and its application will be expanded.

  9. Modification of metal–InGaAs Schottky barrier behaviour by atomic layer deposition of ultra-thin Al{sub 2}O{sub 3} interlayers

    Energy Technology Data Exchange (ETDEWEB)

    Chauhan, Lalit [School of Physical Sciences, Dublin City University, Dublin 9 (Ireland); Gupta, Suman; Jaiswal, Piyush; Bhat, Navakanta; Shivashankar, S.A. [Centre for Nano Science and Engineering (CeNSE), Indian Institute of Science, Bangalore 560012 (India); Hughes, G. [School of Physical Sciences, Dublin City University, Dublin 9 (Ireland)

    2015-08-31

    The effect of inserting ultra-thin atomic layer deposited Al{sub 2}O{sub 3} dielectric layers (1 nm and 2 nm thick) on the Schottky barrier behaviour for high (Pt) and low (Al) work function metals on n- and p-doped InGaAs substrates has been investigated. Rectifying behaviour was observed for the p-type substrates (both native oxide and sulphur passivated) for both the Al/p-InGaAs and Al/Al{sub 2}O{sub 3}/p-InGaAs contacts. The Pt contacts directly deposited on p-InGaAs displayed evidence of limited rectification which increased with Al{sub 2}O{sub 3} interlayer thickness. Ohmic contacts were formed for both metals on n-InGaAs in the absence of an Al{sub 2}O{sub 3} interlayer, regardless of surface passivation. However, limited rectifying behaviour was observed for both metals on the 2 nm Al{sub 2}O{sub 3}/n-InGaAs samples for the sulphur passivated InGaAs surface, indicating the importance of both surface passivation and the presence of an ultra-thin dielectric interlayer on the current–voltage characteristics displayed by these devices. - Highlights: • Investigation of the modification of metal–InGaAs Schottky barrier (SB) behaviour • Improving metal–InGaAs interface by sulphur passivation and ultrathin interlayer • Examine the effect of low work function and high work function metals on SB • Different SB behaviours observed on both n-type InGaAs and p-type InGaAs • Metal/n-InGaAs interface is more strongly pinned than the metal/p-InGaAs interface.

  10. Hybrid Thin Film Organosilica Sol-Gel Coatings To Support Neuronal Growth and Limit Astrocyte Growth.

    Science.gov (United States)

    Capeletti, Larissa Brentano; Cardoso, Mateus Borba; Dos Santos, João Henrique Zimnoch; He, Wei

    2016-10-07

    Thin films of silica prepared by a sol-gel process are becoming a feasible coating option for surface modification of implantable neural sensors without imposing adverse effects on the devices' electrical properties. In order to advance the application of such silica-based coatings in the context of neural interfacing, the characteristics of silica sol-gel are further tailored to gain active control of interactions between cells and the coating materials. By incorporating various readily available organotrialkoxysilanes carrying distinct organic functional groups during the sol-gel process, a library of hybrid organosilica coatings is developed and investigated. In vitro neural cultures using PC12 cells and primary cortical neurons both reveal that, among these different types of hybrid organosilica, the introduction of aminopropyl groups drastically transforms the silica into robust neural permissive substrate, supporting neuron adhesion and neurite outgrowth. Moreover, when this organosilica is cultured with astrocytes, a key type of glial cells responsible for glial scar response toward neural implants, such cell growth promoting effect is not observed. These findings highlight the potential of organo-group-bearing silica sol-gel to function as advanced coating materials to selectively modulate cell response and promote neural integration with implantable sensing devices.

  11. The Enhanced Formaldehyde-Sensing Properties of P3HT-ZnO Hybrid Thin Film OTFT Sensor and Further Insight into Its Stability

    Directory of Open Access Journals (Sweden)

    Huiling Tai

    2015-01-01

    Full Text Available A thin-film transistor (TFT having an organic–inorganic hybrid thin film combines the advantage of TFT sensors and the enhanced sensing performance of hybrid materials. In this work, poly(3-hexylthiophene (P3HT-zinc oxide (ZnO nanoparticles’ hybrid thin film was fabricated by a spraying process as the active layer of TFT for the employment of a room temperature operated formaldehyde (HCHO gas sensor. The effects of ZnO nanoparticles on morphological and compositional features, electronic and HCHO-sensing properties of P3HT-ZnO thin film were systematically investigated. The results showed that P3HT-ZnO hybrid thin film sensor exhibited considerable improvement of sensing response (more than two times and reversibility compared to the pristine P3HT film sensor. An accumulation p-n heterojunction mechanism model was developed to understand the mechanism of enhanced sensing properties by incorporation of ZnO nanoparticles. X-ray photoelectron spectroscope (XPS and atomic force microscopy (AFM characterizations were used to investigate the stability of the sensor in-depth, which reveals the performance deterioration was due to the changes of element composition and the chemical state of hybrid thin film surface induced by light and oxygen. Our study demonstrated that P3HT-ZnO hybrid thin film TFT sensor is beneficial in the advancement of novel room temperature HCHO sensing technology.

  12. Synergy Between Plasma-Assisted ALD and Roll-to-Roll Atmospheric Pressure PE-CVD Processing of Moisture Barrier Films on Polymers

    NARCIS (Netherlands)

    Starostin, S. A.; Keuning, W.; Schalken, J.; Creatore, M.; Kessels, W. M. M.; Bouwstra, J. B.; van de Sanden, M. C. M.; de Vries, H. W.

    2016-01-01

    The synergy between fast (1600 nm · min−1), roll-to-roll plasma-enhanced chemical vapor deposited (PE-CVD) SiO2 layers and plasma-assisted atomic layer deposited (PA-ALD) ultra-thin Al2O3 films has been investigated in terms of moisture permeation barrier properties. The effective and intrinsic

  13. Synergy between plasma-assisted ALD and roll-to-roll atmospheric pressure PE-CVD processing of moisture barrier films on polymers

    NARCIS (Netherlands)

    Starostin, S.A.; Keuning, W.; Schalken, J.R.G.; Creatore, M.; Kessels, W.M.M.; Bouwstra, J.B.; Sanden, van de M.C.M.; Vries, de H.W.

    2016-01-01

    The synergy between fast (1600 nm · min−1), roll-to-roll plasma-enhanced chemical vapor deposited (PE-CVD) SiO2 layers and plasma-assisted atomic layer deposited (PA-ALD) ultra-thin Al2O3 films has been investigated in terms of moisture permeation barrier properties. The effective and intrinsic

  14. Planar structured perovskite solar cells by hybrid physical chemical vapor deposition with optimized perovskite film thickness

    Science.gov (United States)

    Wei, Xiangyang; Peng, Yanke; Jing, Gaoshan; Cui, Tianhong

    2018-05-01

    The thickness of perovskite absorber layer is a critical parameter to determine a planar structured perovskite solar cell’s performance. By modifying the spin coating speed and PbI2/N,N-dimethylformamide (DMF) solution concentration, the thickness of perovskite absorber layer was optimized to obtain high-performance solar cells. Using a PbI2/DMF solution of 1.3 mol/L, maximum power conversion efficiency (PCE) of a perovskite solar cell is 15.5% with a perovskite film of 413 nm at 5000 rpm, and PCE of 14.3% was also obtained for a solar cell with a perovskite film of 182 nm thick. It is derived that higher concentration of PbI2/DMF will result in better perovskite solar cells. Additionally, these perovskite solar cells are highly uniform. In 14 sets of solar cells, standard deviations of 11 sets of solar cells were less than 0.50% and the smallest standard deviation was 0.25%, which demonstrates the reliability and effectiveness of hybrid physical chemical vapor deposition (HPCVD) method.

  15. Poly(3-hexylthiophene) films by electrospray deposition for crystalline silicon/organic hybrid junction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Hiate, Taiga; Miyauchi, Naoto; Tang, Zeguo; Ishikawa, Ryo; Ueno, Keiji; Shirai, Hajime [Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura, Saitama 858-3676 (Japan)

    2012-10-15

    The electrospray deposition (ESD) of poly(3-hexylthiophene) (P3HT) and conductive poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) on P3HT for use in crystalline silicon/organic hybrid heterojunction solar cells on CZ crystalline silicon (c-Si) (100) wafer was investigated using real-time characterization by spectroscopic ellipsometry (SE). In contrast to the nonuniform deposition of products frequently obtained by conventional spin-coating, a uniform deposition of P3HT and PEDOT:PSS films were achieved on flat and textured hydrophobic c-Si(100) wafers by adjusting the deposition conditions. The c-Si/P3HT/PEDOT:PSS heterojunction solar cells exhibited efficiencies of 4.1 and 6.3% on flat and textured c-Si(100) wafers, respectively. These findings suggest that ESD is a promising method for the uniform deposition of P3HT and PEDOT:PSS films on flat and textured hydrophobic substrates. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Resonant silicon nanoparticles for enhancement of light absorption and photoluminescence from hybrid perovskite films and metasurfaces.

    Science.gov (United States)

    Tiguntseva, E; Chebykin, A; Ishteev, A; Haroldson, R; Balachandran, B; Ushakova, E; Komissarenko, F; Wang, H; Milichko, V; Tsypkin, A; Zuev, D; Hu, W; Makarov, S; Zakhidov, A

    2017-08-31

    Recently, hybrid halide perovskites have emerged as one of the most promising types of materials for thin-film photovoltaic and light-emitting devices because of their low-cost and potential for high efficiency. Further boosting their performance without detrimentally increasing the complexity of the architecture is critically important for commercialization. Despite a number of plasmonic nanoparticle based designs having been proposed for solar cell improvement, inherent optical losses of the nanoparticles reduce photoluminescence from perovskites. Here we use low-loss high-refractive-index dielectric (silicon) nanoparticles for improving the optical properties of organo-metallic perovskite (MAPbI 3 ) films and metasurfaces to achieve strong enhancement of photoluminescence as well as useful light absorption. As a result, we observed experimentally a 50% enhancement of photoluminescence intensity from a perovskite layer with silicon nanoparticles and 200% enhancement for a nanoimprinted metasurface with silicon nanoparticles on top. Strong increase in light absorption is also demonstrated and described by theoretical calculations. Since both silicon nanoparticle fabrication/deposition and metasurface nanoimprinting techniques are low-cost, we believe that the developed all-dielectric approach paves the way to novel scalable and highly effective designs of perovskite based metadevices.

  17. Two-dimensional photonic crystal bandedge laser with hybrid perovskite thin film for optical gain

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Hyungrae [Department of Biophysics and Chemical Biology, Seoul National University, Seoul 08826 (Korea, Republic of); Inter-University Semiconductor Research Center, Seoul National University, Seoul 08826 (Korea, Republic of); Bae, Seunghwan [Department of Materials Science and Engineering, Seoul National University, Seoul 08826 (Korea, Republic of); Lee, Myungjae [Inter-University Semiconductor Research Center, Seoul National University, Seoul 08826 (Korea, Republic of); Department of Physics and Astronomy, Seoul National University, Seoul 08826 (Korea, Republic of); Jeon, Heonsu, E-mail: hsjeon@snu.ac.kr [Department of Biophysics and Chemical Biology, Seoul National University, Seoul 08826 (Korea, Republic of); Inter-University Semiconductor Research Center, Seoul National University, Seoul 08826 (Korea, Republic of); Department of Physics and Astronomy, Seoul National University, Seoul 08826 (Korea, Republic of)

    2016-05-02

    We report optically pumped room temperature single mode laser that contains a thin film of hybrid perovskite, an emerging photonic material, as gain medium. Two-dimensional square lattice photonic crystal (PhC) backbone structure enables single mode laser operation via a photonic bandedge mode, while a thin film of methyl-ammonium lead iodide (CH{sub 3}NH{sub 3}PbI{sub 3}) spin-coated atop provides optical gain for lasing. Two kinds of bandedge modes, Γ and M, are employed, and both devices laser in single mode at similar laser thresholds of ∼200 μJ/cm{sup 2} in pulse energy density. Polarization dependence measurements reveal a clear difference between the two kinds of bandedge lasers: isotropic for the Γ-point laser and highly anisotropic for the M-point laser. These observations are consistent with expected modal properties, confirming that the lasing actions indeed originate from the corresponding PhC bandedge modes.

  18. Hybrid pulse anodization for the fabrication of porous anodic alumina films from commercial purity (99%) aluminum at room temperature

    International Nuclear Information System (INIS)

    Chung, C K; Zhou, R X; Chang, W T; Liu, T Y

    2009-01-01

    Most porous anodic alumina (PAA) or anodic aluminum oxide (AAO) films are fabricated using the potentiostatic method from high-purity (99.999%) aluminum films at a low temperature of approximately 0-10 deg. C to avoid dissolution effects at room temperature (RT). In this study, we have demonstrated the fabrication of PAA film from commercial purity (99%) aluminum at RT using a hybrid pulse technique which combines pulse reverse and pulse voltages for the two-step anodization. The reaction mechanism is investigated by the real-time monitoring of current. A possible mechanism of hybrid pulse anodization is proposed for the formation of pronounced nanoporous film at RT. The structure and morphology of the anodic films were greatly influenced by the duration of anodization and the type of voltage. The best result was obtained by first applying pulse reverse voltage and then pulse voltage. The first pulse reverse anodization step was used to form new small cells and pre-texture concave aluminum as a self-assembled mask while the second pulse anodization step was for the resulting PAA film. The diameter of the nanopores in the arrays could reach 30-60 nm.

  19. Controlling the formation and stability of ultra-thin nickel silicides - An alloying strategy for preventing agglomeration

    Science.gov (United States)

    Geenen, F. A.; van Stiphout, K.; Nanakoudis, A.; Bals, S.; Vantomme, A.; Jordan-Sweet, J.; Lavoie, C.; Detavernier, C.

    2018-02-01

    The electrical contact of the source and drain regions in state-of-the-art CMOS transistors is nowadays facilitated through NiSi, which is often alloyed with Pt in order to avoid morphological agglomeration of the silicide film. However, the solid-state reaction between as-deposited Ni and the Si substrate exhibits a peculiar change for as-deposited Ni films thinner than a critical thickness of tc = 5 nm. Whereas thicker films form polycrystalline NiSi upon annealing above 450 ° C , thinner films form epitaxial NiSi2 films that exhibit a high resistance toward agglomeration. For industrial applications, it is therefore of utmost importance to assess the critical thickness with high certainty and find novel methodologies to either increase or decrease its value, depending on the aimed silicide formation. This paper investigates Ni films between 0 and 15 nm initial thickness by use of "thickness gradients," which provide semi-continuous information on silicide formation and stability as a function of as-deposited layer thickness. The alloying of these Ni layers with 10% Al, Co, Ge, Pd, or Pt renders a significant change in the phase sequence as a function of thickness and dependent on the alloying element. The addition of these ternary impurities therefore changes the critical thickness tc. The results are discussed in the framework of classical nucleation theory.

  20. Hybrid Perovskite Thin Film Formation: From Lab Scale Spin Coating to Large Area Blade Coating

    KAUST Repository

    Munir, Rahim

    2017-11-22

    Our reliance on semiconductors is on the rise with the ever growing use of electronics in our daily life. Organic-inorganic hybrid lead halide perovskites have emerged as a prime alternative to current standard and expensive semiconductors because of its use of abundant elements and the ease of solution processing. This thesis has shed light on the ink-to-solid conversion during the one-step solution process of hybrid perovskite formulations from DMF. We utilize a suite of in situ diagnostic probes including high speed optical microscopy, optical reflectance and absorbance, and grazing incidence wide angle x-ray scattering (GIWAXS), all performed during spin coating, to monitor the solution thinning behavior, changes in optical absorbance, and nucleation and growth of crystalline phases of the precursor and perovskite. The starting formulation experiences solvent-solute interactions within seconds of casting, leading to the formation of a wet gel with nanoscale features visible by in situ GIWAXS. The wet gel subsequently gives way to the formation of ordered precursor solvates (equimolar iodide and chloride solutions) or disordered precursor solvates (equimolar bromide or 3:1 chloride), depending upon the halide and MAI content. The ordered precursor solute phases are stable and retain the solvent for long durations, resulting in consistent conversion behavior to the perovskite phase and solar-cell performance. In this thesis, we develop a firm understanding of the solvent engineering process in which an anti-solvent is used during the coating process through the solvent mixture of GBL and DMSO in different ratios. It has been shown that solvent engineering produce pin hole-free films, justifying its wide adoption across the field. We then translate our learnings from the lab scale spin coating process to the industrial friendly blade coating process. Here we compare the ink solidification and film formation mechanisms of CH3NH3PbI3 in solutions we used to

  1. Microwave-assisted synthesis and characterization of poly(acrylic)/SiO2-TiO2 core-shell nanoparticle hybrid thin films

    International Nuclear Information System (INIS)

    Chien, Wen-Chen; Yu, Yang-Yen; Chen, Po-Kan; Yu, Hui-Huan

    2011-01-01

    In this study, poly(acrylic)/SiO 2 -TiO 2 core-shell nanoparticle hybrid thin films were successfully synthesized by microwave-assisted polymerization. The coupling agent 3-(trimethoxysilyl) propyl methacrylate (MSMA) was hydrolyzed with colloidal SiO 2 -TiO 2 core-shell nanoparticles, and then polymerized with two acrylic monomers and initiator to form a precursor solution. The results of this study showed that the spin-coated hybrid films had relatively good surface planarity, high thermal stability, a tunable refractive index (1.525 2 -TiO 2 core-shell nanoparticle hybrid thin films, for potential use in optical applications.

  2. Synthesis and electrochemical properties of Ti-doped DLC films by a hybrid PVD/PECVD process

    Science.gov (United States)

    Jo, Yeong Ju; Zhang, Teng Fei; Son, Myoung Jun; Kim, Kwang Ho

    2018-03-01

    Low electrical conductivity and poor adhesion to metallic substrates are the main drawbacks of diamond-like carbon (DLC) films when used in electrode applications. In this study, Ti-doped DLC films with various Ti contents were synthesized on metal Ti substrates by a hybrid PVD/PECVD process, where PECVD was used for deposition of DLC films and PVD was used for Ti doping. The effects of the Ti doping ratio on the microstructure, adhesion strength, and electrical and electrochemical properties of the DLC films were systematically investigated. An increase in the Ti content led to increased surface roughness and a higher sp2/sp3 ratio of the Ti-DLC films. Ti atoms existed as amorphous-phase Ti carbide when the Ti doping ratio was less than 2.8 at.%, while the nanocrystalline TiC phase was formed in DLC films when the Ti doping ratio was exceeded 4.0 at.%. The adhesion strength, electrical resistivity, electrochemical activity and reversibility of the DLC films were greatly improved by Ti doping. The influence of Ti doping ratio on the electrical and electrochemical properties of the DLC films were also investigated and the best performance was obtained at a Ti content of 2.8 at.%.

  3. Nanostructured films of inorganic-organic hybrid materials for application in photovoltaics; Nanostrukturierte Filme aus anorganisch-organischen Hybridmaterialien fuer die Photovoltaik

    Energy Technology Data Exchange (ETDEWEB)

    Perlich, Jan

    2009-06-25

    Nanostructured thin films of crystalline TiO{sub 2} for applications in photovoltaics were studied. The fabrication of the thin films is based on a hybrid approach. The anorganic metal oxide prepared via a sol-gel synthesis is structurated by the template properties of the applied organic block-copolymer. Via the film epitaxy by means of centrifugal coating first hybrid films (polymer-nanocomposite films) were fabricated, which were changed by calcination into crystalline TiO{sub 2} films with taylored morphology. The successful development of novel preparation approaches to the adaption to consisting conditions in the application field of photovoltaics contains a route to the fine-tuning of the morphology as well as the fabrication of hierarchical morphologies in different configurations. The structural study of the single nanostructurated TiO{sub 2} films up to the functional multilayer arrangement as photovoltaic demonstration cell was performed with conventionally imaging methods, as for instance scanning force microscopy and electron microscopy as well as the special small-angle X-ray scattering method under rigid incident angle (GISAXS). [German] Es wurden nanostrukturierte duenne Filme aus kristallinem TiO{sub 2} fuer Anwendungen in der Photovoltaik untersucht. Die Herstellung der duennen Filme basiert auf einem Hybridansatz. Das ueber eine Sol-Gel-Synthese bereitgestellte anorganische Metalloxid wird durch die Template-Eigenschaften des eingesetzten organischen Block-Copolymers strukturiert. Ueber die Filmaufbringung mittels Schleuderbeschichtung wurden zunaechst Hybridfilme (Polymer-Nanokompositfilme) hergestellt, die durch Kalzinierung in kristalline TiO{sub 2}-Filme mit massgeschneiderter Morphologie umgewandelt werden. Die erfolgreiche Entwicklung von neuartigen Praeparationsansaetzen zur Adaption an bestehende Gegebenheiten im Anwendungsgebiet der Photovoltaik beinhaltet eine Route zur Feineinstellung der Morphologie sowie die Herstellung von

  4. Electrodeposition of zinc oxide/tetrasulfonated copper phthalocyanine hybrid thin film for dye-sensitized solar cell application

    Energy Technology Data Exchange (ETDEWEB)

    Luo Xinze [Key Laboratory of Polyoxometalates Science of Ministry of Education, College of Chemistry, Northeast Normal University, Changchun 130024 (China); College of Chemistry and Biological Science, Yili Normal University, Yining 835000, (China); Xu Lin, E-mail: linxu@nenu.edu.cn [Key Laboratory of Polyoxometalates Science of Ministry of Education, College of Chemistry, Northeast Normal University, Changchun 130024 (China); Xu Bingbing; Li Fengyan [Key Laboratory of Polyoxometalates Science of Ministry of Education, College of Chemistry, Northeast Normal University, Changchun 130024 (China)

    2011-05-15

    Hybrid film of zinc oxide (ZnO) and tetrasulfonated copper phthalocyanine (TSPcCu) was grown on an indium tin oxide (ITO) glass by one-step cathodic electrodeposition from aqueous mixtures of Zn(NO{sub 3}){sub 2}, TSPcCu and KCl. The addition of TSPcCu strongly influences the morphology and crystallographic orientation of the ZnO. The nanosheets stack of ZnO leads to a porous surface structure which is advantageous to further adsorb organic dyes. The photovoltaic properties were investigated by assembling the DSSC device based on both the only ZnO film and the ZnO/TSPcCu hybrid films. Photoelectrochemical analysis revealed that the optimized DSSC device with TSPcCu represented a more than three-fold improvement in power conversion efficiency than the device without TSPcCu. The DSSC based on ZnO/TSPcCu hybrid films demonstrates an open circuit voltage of 0.308 V, a short circuit current of 90 {mu}A cm{sup -2}, a fill factor of 0.26, and a power conversion efficiency of 0.14%.

  5. Electrodeposition of zinc oxide/tetrasulfonated copper phthalocyanine hybrid thin film for dye-sensitized solar cell application

    International Nuclear Information System (INIS)

    Luo Xinze; Xu Lin; Xu Bingbing; Li Fengyan

    2011-01-01

    Hybrid film of zinc oxide (ZnO) and tetrasulfonated copper phthalocyanine (TSPcCu) was grown on an indium tin oxide (ITO) glass by one-step cathodic electrodeposition from aqueous mixtures of Zn(NO 3 ) 2 , TSPcCu and KCl. The addition of TSPcCu strongly influences the morphology and crystallographic orientation of the ZnO. The nanosheets stack of ZnO leads to a porous surface structure which is advantageous to further adsorb organic dyes. The photovoltaic properties were investigated by assembling the DSSC device based on both the only ZnO film and the ZnO/TSPcCu hybrid films. Photoelectrochemical analysis revealed that the optimized DSSC device with TSPcCu represented a more than three-fold improvement in power conversion efficiency than the device without TSPcCu. The DSSC based on ZnO/TSPcCu hybrid films demonstrates an open circuit voltage of 0.308 V, a short circuit current of 90 μA cm -2 , a fill factor of 0.26, and a power conversion efficiency of 0.14%.

  6. Purple-bacterial photosynthetic reaction centers and quantum-dot hybrid-assemblies in lecithin liposomes and thin films.

    Science.gov (United States)

    Lukashev, Eugeny P; Knox, Petr P; Gorokhov, Vladimir V; Grishanova, Nadezda P; Seifullina, Nuranija Kh; Krikunova, Maria; Lokstein, Heiko; Paschenko, Vladimir Z

    2016-11-01

    Quantum dots (QDs) absorb ultraviolet and long-wavelength visible light energy much more efficiently than natural bacterial light-harvesting proteins and can transfer the excitation energy to photosynthetic reaction centers (RCs). Inclusion of RCs combined with QDs as antennae into liposomes opens new opportunities for using such hybrid systems as a basis for artificial energy-transforming devices that potentially can operate with greater efficiency and stability than devices based only on biological components or inorganic components alone. RCs from Rhodobacter sphaeroides and QDs (CdSe/ZnS with hydrophilic covering) were embedded in lecithin liposomes by extrusion of a solution of multilayer lipid vesicles through a polycarbonate membrane or by dialysis of lipids and proteins dispersed with excess detergent. The efficiency of RC and QD interaction within the liposomes was estimated using fluorescence excitation spectra of the photoactive bacteriochlorophyll of the RCs and by measuring the fluorescence decay kinetics of the QDs. The functional activity of the RCs in hybrid complexes was fully maintained, and their stability was even increased. The efficiency of energy transfer between QDs and RCs and conditions of long-term stability of function of such hybrid complexes in film preparations were investigated as well. It was found that dry films containing RCs and QDs, maintained at atmospheric humidity, are capable of maintaining their functional activity for at least some months as judged by measurements of their spectral characteristics, efficiency of energy transfer from QDs to RCs and RC electron transport activity. Addition of trehalose to the films increases the stability further, especially for films maintained at low humidity. These stable hybrid film structures are promising for further studies towards developing new phototransformation devices for biotechnological applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Tailoring the vortex pinning strength of YBCO thin films by systematic incorporation of hybrid artificial pinning centers

    International Nuclear Information System (INIS)

    Jha, Alok K; Matsumoto, Kaname; Horide, Tomoya; Saini, Shrikant; Mele, Paolo; Ichinose, Ataru; Yoshida, Yutaka; Awaji, Satoshi

    2015-01-01

    The effect of hybrid (columnar and spherical together) artificial pinning centers (APCs) on the vortex pinning properties of YBa 2 Cu 3 O 7−δ (YBCO) thin films is investigated in detail on the basis of variation of critical current density (J C ) with applied magnetic field and also with the orientation of the applied magnetic field at 65 K and 77 K. Premixed YBCO + BaSnO 3 composite targets are used for the deposition of the YBCO films which consist of self-assembled BaSnO 3 nanocolumns (1D APCs); on the other hand, for the deposition of the YBCO films with hybrid APCs (BaSnO 3 nanocolumns together with Y 2 O 3 nanoparticles), the surface of the premixed YBCO + BaSnO 3 composite targets are modified by putting a thin Y 2 O 3 sectored piece on the premixed YBCO + BaSnO 3 composite targets by means of silver paste. F pmax value increases systematically with incorporation of 1D and 1D and 3D APCs and it also shifts towards higher applied magnetic fields. Films with 1D APCs exhibit a strong J C peak at Θ = 0° (H//c-axis) whereas films consisting of hybrid APCs exhibit enhanced J C at all the investigated angular regimes. A possible mechanism of vortex pinning in samples with hybrid APCs is also discussed suggesting the role of 1D and 3D APCs. (paper)

  8. Color-sensitive photoconductivity of nanostructured ZnO/dye hybrid films prepared by one-step electrodeposition

    Energy Technology Data Exchange (ETDEWEB)

    Oekermann, T. [Gifu University, Graduate School of Engineering, Yanagido 1-1, Gifu 501-1193 (Japan) and University of Hannover, Institute of Physical Chemistry and Electrochemistry, Callinstrasse 3-3A, 30167 Hannover (Germany)]. E-mail: torsten.oekermann@pci.uni-hannover.de; Yoshida, T. [Gifu University, Graduate School of Engineering, Yanagido 1-1, Gifu 501-1193 (Japan)]. E-mail: yoshida@apchem.gifu-u.ac.jp; Tada, H. [Institute for Molecular Science, Okazaki National Research Institutes, Myodaiji, Okazaki 444-8585 (Japan); Minoura, H. [Gifu University, Graduate School of Engineering, Yanagido 1-1, Gifu 501-1193 (Japan)

    2006-07-26

    Nanostructured ZnO/dye hybrid films prepared by one-step electrodeposition have been investigated in conductivity and photoconductivity measurements in view of applications in dye-sensitized solar cells (DSSC) and in optoelectronics. Highly porous ZnO/eosin Y films, which were obtained at potentials < - 0.9 V vs. SCE, were found to have a very high conductivity already in the dark, probably because of a higher n-doping, which is due to a higher concentration of Zn atoms in the film. On the other hand, less porous or non-porous films, which were obtained at more positive potentials and in which the dye molecules are located within the ZnO crystals, were found to show a much higher sensitivity to illumination with visible light in photoconductivity measurements due to a higher absolute photoconductivity and a lower conductivity in the dark.

  9. Color-sensitive photoconductivity of nanostructured ZnO/dye hybrid films prepared by one-step electrodeposition

    International Nuclear Information System (INIS)

    Oekermann, T.; Yoshida, T.; Tada, H.; Minoura, H.

    2006-01-01

    Nanostructured ZnO/dye hybrid films prepared by one-step electrodeposition have been investigated in conductivity and photoconductivity measurements in view of applications in dye-sensitized solar cells (DSSC) and in optoelectronics. Highly porous ZnO/eosin Y films, which were obtained at potentials < - 0.9 V vs. SCE, were found to have a very high conductivity already in the dark, probably because of a higher n-doping, which is due to a higher concentration of Zn atoms in the film. On the other hand, less porous or non-porous films, which were obtained at more positive potentials and in which the dye molecules are located within the ZnO crystals, were found to show a much higher sensitivity to illumination with visible light in photoconductivity measurements due to a higher absolute photoconductivity and a lower conductivity in the dark

  10. Indium–gallium–zinc oxide thin film transistors with a hybrid-channel structure for defect suppression and mobility improvement

    International Nuclear Information System (INIS)

    Lin, Huang-Kai; Su, Liang-Yu; Hung, Chia-Chin; Huang, JianJang

    2013-01-01

    In this work, we explore an indium gallium zinc oxide (IGZO) thin film transistor structure with a vacuum annealed IGZO thin film inserted between the dielectric and typical channel layers. The device demonstrates a better subthreshold swing and field-effect mobility due to the suppression of defects in the channel and the channel/dielectric interface. The hybrid channel structure also exhibits the flexibility of adjusting the threshold voltage. The superior carrier mobility was then verified from the transient response of the inverter circuit constructed by the devices. - Highlights: • Additional in-situ annealed In–Ga–ZnO film was inserted in thin film transistor (TFT). • Traps are suppressed and field effect mobility is improved in the TFT. • An inverter with the device structure has a better transient response

  11. Influence of the supporting salt concentration on the electrodeposition of ZnO/eosin Y hybrid films

    Energy Technology Data Exchange (ETDEWEB)

    Boeckler, C.; Oekermann, T. [Institute of Physical Chemistry and Electrochemistry, Leibniz University Hannover (Germany); Saruban, M.; Ichinose, K.; Yoshida, T. [Center of Innovative Photovoltaic Systems (CIPS), Environmental and Renewable Energy Systems (ERES) Division, Graduate School of Engineering, Gifu University (Japan)

    2008-10-15

    ZnO/eosin Y hybrid films were electrodeposited from O{sub 2}-saturated ZnCl{sub 2}-solution under variation of the concentration of the supporting salt KCl. The supporting salt concentration was found to have a significant influence on the amount of dye loading and the morphology of the ZnO/eosin Y films. By decreasing the supporting salt concentration to 0.01 M KCl, porous films with a high dye loading can be obtained at potentials of -0.8 V vs. SCE at low eosin Y concentrations in the electrodeposition bath, which usually only lead to porous films at potentials where eosin Y is reduced (<-0.9 V vs. SCE). (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. Indium–gallium–zinc oxide thin film transistors with a hybrid-channel structure for defect suppression and mobility improvement

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Huang-Kai; Su, Liang-Yu; Hung, Chia-Chin [Graduate Institute of Photonics and Optoelectronics, National Taiwan University, 1, Roosevelt Road, Sec. 4, Taipei 106, Taiwan (China); Huang, JianJang, E-mail: jjhuang@cc.ee.ntu.edu.tw [Graduate Institute of Photonics and Optoelectronics, National Taiwan University, 1, Roosevelt Road, Sec. 4, Taipei 106, Taiwan (China); Department of Electrical Engineering, National Taiwan University, 1, Roosevelt Road, Sec. 4, Taipei 106, Taiwan (China)

    2013-07-01

    In this work, we explore an indium gallium zinc oxide (IGZO) thin film transistor structure with a vacuum annealed IGZO thin film inserted between the dielectric and typical channel layers. The device demonstrates a better subthreshold swing and field-effect mobility due to the suppression of defects in the channel and the channel/dielectric interface. The hybrid channel structure also exhibits the flexibility of adjusting the threshold voltage. The superior carrier mobility was then verified from the transient response of the inverter circuit constructed by the devices. - Highlights: • Additional in-situ annealed In–Ga–ZnO film was inserted in thin film transistor (TFT). • Traps are suppressed and field effect mobility is improved in the TFT. • An inverter with the device structure has a better transient response.

  13. Bioelectrochemistry of heme peptide at seamless three-dimensional carbon nanotubes/graphene hybrid films for highly sensitive electrochemical biosensing.

    Science.gov (United States)

    Komori, Kikuo; Terse-Thakoor, Trupti; Mulchandani, Ashok

    2015-02-18

    A seamless three-dimensional hybrid film consisting of carbon nanotubes grown at the graphene surface (CNTs/G) is a promising material for the application to highly sensitive enzyme-based electrochemical biosensors. The CNTs/G film was used as a conductive nanoscaffold for enzymes. The heme peptide (HP) was immobilized on the surface of the CNTs/G film for amperometric sensing of H2O2. Compared with flat graphene electrodes modified with HP, the catalytic current for H2O2 reduction at the HP-modified CNTs/G electrode increased due to the increase in the surface coverage of HP. In addition, microvoids in the CNTs/G film contributed to diffusion of H2O2 to modified HP, resulting in the enhancement of the catalytic cathodic currents. The kinetics of the direct electron transfer from the CNTs/G electrode to compound I and II of modified HP was also analyzed.

  14. Enhanced luminescence properties of hybrid Alq{sub 3}/ZnO (organic/inorganic) composite films

    Energy Technology Data Exchange (ETDEWEB)

    Cuba, M.; Muralidharan, G., E-mail: muraligru@gmail.com

    2014-12-15

    Pristine tris-(8-hydroxyquionoline)aluminum(Alq{sub 3}) and (Alq{sub 3}/ZnO hybrid) composites containing different weight percentages (5 wt%, 10 wt%, 20 wt%, 30 wt%, 40 wt% and 50 wt%) of ZnO in Alq{sub 3} were synthesized and coated on to a glass substrate using the dip coating method. The optimum concentration of ZnO in Alq{sub 3} films to get the best luminescence yield has been identified. XRD pattern reveals the amorphous nature of pure Alq{sub 3} film. The Alq{sub 3} films containing different weight percentages of ZnO show the presence of crystalline ZnO in Alq{sub 3}/ZnO composite films. The FTIR spectrum confirms the formation of quinoline with absorption in the region 600−800 cm{sup −1}. The hybrid Alq{sub 3}/ZnO composite films indicate the presence of Zn−O vibration band along with the corresponding Alq{sub 3} band. The band gap (HOMO–LUMO) of Alq{sub 3} film was calculated using absorption spectra and it is 2.87 eV for pristine films while it is 3.26 eV, 3.21 eV, 3.14 eV, 3.10 eV, 3.13 eV and 3.20 eV for the composite films containing 5–50 wt% of ZnO. The photoluminescence (PL) spectra of Alq{sub 3} films show a maximum PL intensity at 514 nm when excited at 390 nm. The ZnO incorporated composite films (Alq{sub 3}/ZnO) exhibit an emission in 485 nm and 514 nm. The composite films containing 30 wt% of ZnO exhibit maximum luminescence yield. - Highlights: • The pure Alq{sub 3} and Alq{sub 3}/ZnO composite were synthesized and coated on to a glass substrate using dip coating method. • Alq{sub 3}/ZnO composite film containing 30 wt% of ZnO exhibits two fold increases in luminescence intensity. • The shielding effect of ZnO on the Alq{sub 3} material suppresses the interactions among the host molecules in the excited state. • This leads to enhance the luminescence intensity in composite films.

  15. Layered Ni(OH)2-Co(OH)2 films prepared by electrodeposition as charge storage electrodes for hybrid supercapacitors.

    Science.gov (United States)

    Nguyen, Tuyen; Boudard, Michel; Carmezim, M João; Montemor, M Fátima

    2017-01-04

    Consecutive layers of Ni(OH) 2 and Co(OH) 2 were electrodeposited on stainless steel current collectors for preparing charge storage electrodes of high specific capacity with potential application in hybrid supercapacitors. Different electrodes were prepared consisting on films of Ni(OH) 2 , Co(OH) 2 , Ni 1/2 Co 1/2 (OH) 2 and layered films of Ni(OH) 2 on Co(OH) 2 and Co(OH) 2 on Ni(OH) 2 to highlight the advantages of the new architecture. The microscopy studies revealed the formation of nanosheets in the Co(OH) 2 films and of particles agglomerates in the Ni(OH) 2 films. Important morphological changes were observed in the double hydroxides films and layered films. Film growth by electrodeposition was governed by instantaneous nucleation mechanism. The new architecture composed of Ni(OH) 2 on Co(OH) 2 displayed a redox response characterized by the presence of two peaks in the cyclic voltammograms, arising from redox reactions of the metallic species present in the layered film. These electrodes revealed a specific capacity of 762 C g -1 at the specific current of 1 A g -1 . The hybrid cell using Ni(OH) 2 on Co(OH) 2 as positive electrode and carbon nanofoam paper as negative electrode display specific energies of 101.3 W h g -1 and 37.8 W h g -1 at specific powers of 0.2 W g -1 and 2.45 W g -1 , respectively.

  16. Research Update: Hybrid organic-inorganic perovskite (HOIP thin films and solar cells by vapor phase reaction

    Directory of Open Access Journals (Sweden)

    Po-Shen Shen

    2016-09-01

    Full Text Available With the rapid progress in deposition techniques for hybrid organic-inorganic perovskite (HOIP thin films, this new class of photovoltaic (PV technology has achieved material quality and power conversion efficiency comparable to those established technologies. Among the various techniques for HOIP thin films preparation, vapor based deposition technique is considered as a promising alternative process to substitute solution spin-coating method for large-area or scale-up preparation. This technique provides some unique benefits for high-quality perovskite crystallization, which are discussed in this research update.

  17. Incorporated W Roles on Microstructure and Properties of W-C:H Films by a Hybrid Linear Ion Beam Systems

    Directory of Open Access Journals (Sweden)

    Peng Guo

    2013-01-01

    Full Text Available W-incorporated diamond-like carbon (W-C:H films were fabricated by a hybrid beams system consisting of a DC magnetron sputtering and a linear ion source. The W concentration (1.08~31.74 at.% in the film was controlled by varying the sputtering current. The cross-sectional topography, composition, and microstructure of the W-C:H films were investigated by SEM, XPS, TEM, and Raman spectroscopy. The mechanical and tribological properties of the films as a function of W concentration were evaluated by a stress-tester, nanoindentation, and ball-on-disk tribometer, respectively. The results showed that films mainly exhibited the feature of amorphous carbon when W concentration of the films was less than 4.38 at.%, where the incorporated W atoms would be bonded with C atoms and resulted in the formation of WC1-x nanoparticles. The W-C:H film with 4.38 at.% W concentration showed a minimum value of residual compressive stress, a higher hardness, and better tribological properties. Beyond this W concentration range, both the residual stress and mechanical properties were deteriorated due to the growth of tungsten carbide nanoparticles in the carbon matrix.

  18. Effects of Na incorporation and plasma treatment on Bi{sub 2}S{sub 3} ultra-thin layers

    Energy Technology Data Exchange (ETDEWEB)

    Moreno-Garcia, H., E-mail: hamog@ier.unam.mx [Laboratorio de Espectroscopía, Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Apartado Postal 48-3, 62210 Cuernavaca, Morelos (Mexico); Messina, S. [Universidad Autónoma de Nayarit, Ciudad de la Cultura “Amado Nervo” S/N, C.P. 63155 Tepic, Nayarit (Mexico); Calixto-Rodriguez, M. [Universidad Tecnológica Emiliano Zapata del Estado de Morelos, Av. Universidad Tecnológica No. 1, C.P. 62760 Emiliano Zapata, Morelos (Mexico); Martínez, H. [Laboratorio de Espectroscopía, Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Apartado Postal 48-3, 62210 Cuernavaca, Morelos (Mexico)

    2016-04-01

    As-deposited bismuth sulfide thin films prepared by means of a chemical bath deposition were treated with argon AC plasma. In this paper, we present the results on the physical modifications which were observed when a pre-treatment, containing a solution of 1 M sodium hydroxide, was applied to the glass substrates before depositing the bismuth sulfide. The bismuth sulfide thin films were characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy, atomic force microscopy, UV–VIS, and electrical measurements. The XRD analysis demonstrated an enhancement in the crystalline properties, as well as an increment in the crystal size. The energy band gap value was calculated as 1.60 eV. Changes in photoconductivity (σ{sub p}) values were also observed due to the pre-treatment in NaOH. A value of σ{sub p} = 6.2 × 10{sup −6} (Ω cm){sup −1} was found for samples grown on substrates without pre-treatment, and a value of σ{sub p} = 0.28 (Ω cm){sup −1} for samples grown on substrates with pre-treatment. Such σ{sub p} values are optimal for the improvement of solar cells based on Bi{sub 2}S{sub 3} thin films as absorber material. - Highlights: • We report our findings about Na incorporation and plasma treatment on Bi{sub 2}S{sub 3} thin layers. • The Na pre-treatment improves the structural and electrical properties of Bi{sub 2}S{sub 3} films. • The E{sub g} value was 1.60 eV for films with pre-treatment with NaOH and treatment in Ar plasma.

  19. Enhanced performance of GaN-based light-emitting diodes with graphene/Ag nanowires hybrid films

    Directory of Open Access Journals (Sweden)

    Zhi Li

    2013-04-01

    Full Text Available Incorporating Ag nanowires with graphene resulted in improved electrical conductivity and enhanced contact properties between graphene and p-GaN. The graphene/AgNWs hybrid films exhibited high transmittance and lower sheet resistance compared to bare graphene. The specific contact resistance between graphene and p-GaN reduced nearly an order of magnitude with the introduction of AgNWs. As a result, light emitting diodes based on the hybrid films showed 44% lower forward voltage and 2-fold higher light output power. The enhanced performance was attributed to the bridging by AgNWs of cracks, grain boundaries in graphene and the reduction of Schottky barrier height at graphene/ p-GaN interface.

  20. Radiation preparation of graphene/carbon nanotubes hybrid fillers for mechanical reinforcement of poly(vinyl alcohol) films

    Science.gov (United States)

    Ma, Hui-Ling; Zhang, Long; Zhang, Youwei; Wang, Shuojue; Sun, Chao; Yu, Hongyan; Zeng, Xinmiao; Zhai, Maolin

    2016-01-01

    Graphene/carbon nanotubes (G/CNTs) hybrid fillers were synthesized by γ-ray radiation reduction of graphene oxide (GO) in presence of CNTs. The obtained hybrid fillers with three-dimensional (3D) interconnected network structure were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Poly(vinyl alcohol) (PVA) composite films with enhanced mechanical properties and thermal stability were subsequently prepared by solution blending of G/CNTs with PVA matrix. The tensile strength and Young's modulus of PVA composite films containing 1 wt% G/CNTs were measured to be 81.9 MPa and 3.9 GPa respectively, which were 56% and 33.6% higher than those of pure PVA. These substantial improvements could be attributed to the interconnected 3D structure of G/CNTs, homogeneous dispersion as well as the strong hydrogen-bonding interaction between G/CNTs and PVA macromolecular chains.

  1. Bio-hybridization of nanobactericides with cellulose films for effective treatment against members of ESKAPE multi-drug-resistant pathogens

    Science.gov (United States)

    Baker, Syed; Volova, Tatiana; Prudnikova, Svetlana V.; Shumilova, Anna A.; Perianova, Olga V.; Zharkov, Sergey M.; Kuzmin, Andrey; Olga, Kondratenka; Bogdan, Kiryukhin; Shidlovskiy, Ivan P.; Potkina, Zoya K.; Khohlova, Olga Y.; Lobova, Tatiana I.

    2018-03-01

    The rapid expansion of drug-resistant pathogens has created huge global impact and development of novel antimicrobial leads is one of the top priority studies in the current scenario. The present study aims to develop bio-hybridized nanocellulose films which comprise of phytogenic silver nanobactericides. The nanobactericides were synthesized by treating 1 mM silver nitrate with aqueous extract of Chamerion angustifolium which reduced the metal salt to produce polydispersed nanobactericides which were tested against the members of ESKAPE drug-resistant communities. The synthesized silver nanobactericides were subjected to characterization with UV-visible spectra which displayed maximum absorbance at 408 nm. The bio-molecular interaction of phyto-constituents to mediate synthesis and stabilization of nanobactericides was studied with Fourier-transform infrared spectroscopy (FTIR) which depicted functional groups associated with nanobactericides. The crystalline nature was studied with X-ray diffraction (XRD) which showed Bragg's intensities at 2θ angle which denoted (111), (200), (220), and (311) planes. The morphological characteristics of silver nanobactericides were defined with transmission electron Microscopy (TEM) image which displayed polydispersity of silver nanobactericides with size ranging from 2 to 40 nm. The synthesized nanobactericides showed a significant activity against MRSA strain with 21 mm zone of inhibition. The minimal inhibitory concentration of silver nanobactericides to inhibit the growth of test pathogens was also determined which ranged between 0.625 and 1.25 μg/ml. The silver nanobactericides were bio-hybridized onto nanocellulose films produced by Komagataeibacter xylinus B-12068 culture strain. The films were dried to determine the mechanical properties which showed increased in Young's modulus and tensile strength in comparison with control bacterial cellulose films. Overall, the results obtained in the present investigation are

  2. Measurement of radiation induced transients in hybrid microcircuits by magnetic thin film sensor/recorders

    International Nuclear Information System (INIS)

    Hsieh, E.J.; Vindelov, K.E.; Brown, T.G.; Miller, D.E.

    1976-01-01

    Magnetic thin film transient current sensor/recorders were modified to make two types of nuclear test measurements, transient currents in hybrid microcircuits and internal electromagnetic pulse (IEMP) fields. The measurements were made possible by the invention of split-domain sensor/recorders which can measure bilateral currents and can be reset and readout on location. The sensor/recorders were used in two underground nuclear tests and numerous calibration tests in radiation-simulation machines. The data showed that the nuclear environment had negligible effect on the sensor/recorder's operation and the recorded informations on the sensor/recorders were the signals intended to be monitored. Also, the experimental data agreed with the theoretical analysis in controlled experiments. The data were examined first by on location readout with a magnetic tape viewer and later by Kerr magneto-optic readout in the laboratory. To translate the data into current readings, we reconstructed facsimile data (on each of the sensor/recorders) in the laboratory by current pulses with the same pulse width as the radiation event. An additional check on the accuracy of the data was made by using both the sensor/recorder and the conventional pickup-oscilloscope-camera technique to monitor the same current lead in a simulated radiation environment. Over five runs were made, and the agreement among the two measurement methods was within 25%. The data collectively implied that the measurements were reliable and dependable

  3. Sunlight-charged electrochromic battery based on hybrid film of tungsten oxide and polyaniline

    Science.gov (United States)

    Chang, Xueting; Hu, Ruirui; Sun, Shibin; Liu, Jingrong; Lei, Yanhua; Liu, Tao; Dong, Lihua; Yin, Yansheng

    2018-05-01

    Electrochromic (EC) energy storage devices that could realize the multifunctional integration of energy storage and electrochromism have gained much recent attention. Herein, an EC battery based on the hybrid film of W18O49 and polyaniline (PANI) is developed and assembled, which integrates energy storage and EC functions in one device. The W18O49/PANI-EC battery delivers a discharging capacity of 52.96 mA h g-1, which is about two times higher than that of the W18O49-EC battery. Sunlight irradiation could greatly promote the oxidation reactions of both W18O49 and PANI during the charging process of the W18O49/PANI-EC battery, thus effectively accelerating the charging rate. This work provides a green, convenient, environmentally friendly, and cost-free charging strategy for the EC energy systems and could further advance the development of the multifunctional EC devices based on the organic/inorganic composites.

  4. Novel Flexible Transparent Conductive Films with Enhanced Chemical and Electromechanical Sustainability: TiO2 Nanosheet-Ag Nanowire Hybrid.

    Science.gov (United States)

    Sohn, Hiesang; Kim, Seyun; Shin, Weonho; Lee, Jong Min; Lee, Hyangsook; Yun, Dong-Jin; Moon, Kyoung-Seok; Han, In Taek; Kwak, Chan; Hwang, Seong-Ju

    2018-01-24

    Flexible transparent conductive films (TCFs) of TiO 2 nanosheet (TiO 2 NS) and silver nanowire (Ag NW) network hybrid were prepared through a simple and scalable solution-based process. The as-formed TiO 2 NS-Ag NW hybrid TCF shows a high optical transmittance (TT: 97% (90.2% including plastic substrate)) and low sheet resistance (R s : 40 Ω/sq). In addition, the TiO 2 NS-Ag NW hybrid TCF exhibits a long-time chemical/aging and electromechanical stability. As for the chemical/aging stability, the hybrid TCF of Ag NW and TiO 2 NS reveals a retained initial conductivity (ΔR s /R s 4000%) or RuO 2 NS-Ag NW hybrid (ΔR s /R s > 200%). As corroborated by the density functional theory simulation, the superb chemical stability of TiO 2 NS-Ag NW hybrid is attributable to the unique role of TiO 2 NS as a barrier, which prevents Ag NW's chemical corrosion via the attenuated adsorption of sulfidation molecules (H 2 S) on TiO 2 NS. With respect to the electromechanical stability, in contrast to Ag NWs (ΔR/R 0 ∼ 152.9%), our hybrid TCF shows a limited increment of fractional resistivity (ΔR/R 0 ∼ 14.4%) after 200 000 cycles of the 1R bending test (strain: 6.7%) owing to mechanically welded Ag NW networks by TiO 2 NS. Overall, our unique hybrid of TiO 2 NS and Ag NW exhibits excellent electrical/optical properties and reliable chemical/electromechanical stabilities.

  5. Supercapacitive properties of hybrid films of manganese dioxide and polyaniline based on active carbon in organic electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Wu-yuan; Wang, Wei; He, Ben-lin; Sun, Ming-liang; Yin, Yan-sheng [Institute of Materials Science and Engineering, Ocean University of China, Songling Road 238, Qingdao 266100, Shandong Province (China)

    2010-11-01

    This is the first report about supercapacitive performance of hybrid film of manganese dioxide (MnO{sub 2}) and polyaniline (PANI) in an organic electrolyte (1.0 M LiClO{sub 4} in acetonitrile). In this work, a high surface area and conductivity of active carbon (AC) electrode is used as a substrate for PANI/MnO{sub 2} film electro-codeposition. The redox properties of the coated PANI/MnO{sub 2} thin film exhibit ideal capacitive behaviour in 1 M LiClO{sub 4}/AN. The specific capacitance (SC) of PANI/MnO{sub 2} hybrid film is as high as 1292 F g{sup -1} and maintains about 82% of the initial capacitance after 1500 cycles at a current density of 4.0 mA cm{sup -2}, and the coulombic efficiency ({eta}) is higher than 95%. An asymmetric capacitor has been developed with the PANI/MnO{sub 2}/AC positive and pure AC negative electrodes, which is able to deliver a specific energy as high as 61 Wh kg{sup -1} at a specific power of 172 W kg{sup -1} in the range of 0-2.0 V. These results indicate that the organic electrolyte is a promising candidate for PANI/MnO{sub 2} material application in supercapacitors. (author)

  6. Enhanced efficiency of hybrid amorphous silicon solar cells based on single-walled carbon nanotubes/polymer composite thin film.

    Science.gov (United States)

    Rajanna, Pramod Mulbagal; Gilshteyn, Evgenia; Yagafarov, Timur; Alekseeva, Alena; Anisimov, Anton; Sergeev, Oleg; Neumueller, Alex; Bereznev, Sergei; Maricheva, Jelena; Nasibulin, Albert

    2018-01-09

    We report a simple approach to fabricate hybrid solar cells (HSCs) based on a single-walled carbon nanotube (SWCNT) film and a thin film hydrogenated amorphous silicon (a-Si:H). Randomly oriented high quality SWCNTs with an enhanced conductivity by means of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate are used as a window layer and a front electrode. A series of HSCs are fabricated in ambient conditions with different SWCNT film thicknesses. The polymethylmethacrylate layer drop-casted on fabricated HSCs reduces the reflection fourfold and enhances the short-circuit Jsc, open-circuit Voc, and efficiency by nearly 10%. A state-of-the-art J-V performance is shown for SWCNT/a-Si HSC with an open-circuit voltage of 900 mV and efficiency of 3.4% under simulated one-sun AM 1.5G direct illumination. © 2018 IOP Publishing Ltd.

  7. Enhanced efficiency of hybrid amorphous silicon solar cells based on single-walled carbon nanotubes and polymer composite thin film

    Science.gov (United States)

    Rajanna, Pramod M.; Gilshteyn, Evgenia P.; Yagafarov, Timur; Aleekseeva, Alena K.; Anisimov, Anton S.; Neumüller, Alex; Sergeev, Oleg; Bereznev, Sergei; Maricheva, Jelena; Nasibulin, Albert G.

    2018-03-01

    We report a simple approach to fabricate hybrid solar cells (HSCs) based on a single-walled carbon nanotube (SWCNT) film and thin film hydrogenated amorphous silicon (a-Si:H). Randomly oriented high-quality SWCNTs with conductivity enhanced by means of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate are used as a window layer and a front electrode. A series of HSCs are fabricated in ambient conditions with varying SWCNT film thicknesses. The polymethylmethacrylate layer drop-casted on fabricated HSCs reduces the reflection fourfold and enhances the short-circuit J sc , open-circuit V oc , and efficiency by nearly 10%. A state-of-the-art J-V performance is shown for SWCNT/a-Si HSC with an open-circuit voltage of 900 mV and an efficiency of 3.4% under simulated one-sun AM 1.5 G direct illumination.

  8. Corrosion resistance of siloxane–poly(methyl methacrylate) hybrid films modified with acetic acid on tin plate substrates: Influence of tetraethoxysilane addition

    Energy Technology Data Exchange (ETDEWEB)

    Kunst, S.R.; Cardoso, H.R.P. [LAPEC, Federal University of Rio Grande do Sul – UFRGS, Avenida Bento Gonçalves, 9500 Porto Alegre, RS (Brazil); Oliveira, C.T. [ICET, University Feevale, RS-239, 2755 Novo Hamburgo, RS (Brazil); Santana, J.A.; Sarmento, V.H.V. [Department of Chemistry, Federal University of Sergipe – UFS, Av. Vereador Olímpio Grande s/n, Centro, Itabaiana, SE (Brazil); Muller, I.L. [LAPEC, Federal University of Rio Grande do Sul – UFRGS, Avenida Bento Gonçalves, 9500 Porto Alegre, RS (Brazil); Malfatti, C.F., E-mail: celia.malfatti@ufrgs.br [LAPEC, Federal University of Rio Grande do Sul – UFRGS, Avenida Bento Gonçalves, 9500 Porto Alegre, RS (Brazil)

    2014-04-01

    Highlights: • Siloxane–PMMA film was produced by dip-coating on tin plate substrate. • It was evaluated the influence of (TEOS) addition on siloxane–PMMA hybrid films. • Siloxane–PMMA films without TEOS presented a regular coverage and lowest roughness. • The TEOS addition decrease the corrosion resistance of siloxane–PMMA films. • Siloxane–PMMA without TEOS presented is higher durability in the film wear test. - Abstract: The aim of this paper is to study the corrosion resistance of hybrid films. Tin plate was coated with a siloxane–poly (methyl methacrylate) (PMMA) hybrid film prepared by sol–gel route with covalent bonds between the organic (PMMA) and inorganic (siloxane) phases obtained by hydrolysis and polycondensation of 3-(trimethoxysilylpropyl) methacrylate (TMSM) and polymerization of methyl methacrylate (MMA) using benzoyl peroxide (BPO) as a thermic initiator. Hydrolysis reactions were catalyzed by acetic acid solution avoiding the use of chlorine or stronger acids in the film preparation. The effect of the addition of tetraethoxysilane (TEOS) on the protective properties of the film was evaluated. The hydrophobicity of the film was determined by contact angle measurements, and the morphology was evaluated by scanning electron microscopy (SEM) and profilometry. The local nanostructure was investigated by Fourier transform infrared spectroscopy (FT-IR). The electrochemical behavior of the films was assessed by open circuit potential monitoring, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements in a 0.05 M NaCl solution. The mechanical behavior was evaluated by tribology. The results highlighted that the siloxane–PMMA hybrid films modified with acetic acid are promising anti-corrosive coatings that acts as an efficient diffusion barrier, protecting tin plates against corrosion. However, the coating properties were affected by the TEOS addition, which contributed for the thickness increase

  9. Microstructure and texture evolution of ultra-thin grain-oriented silicon steel sheet fabricated using strip casting and three-stage cold rolling method

    Energy Technology Data Exchange (ETDEWEB)

    Song, Hong-Yu; Liu, Hai-Tao, E-mail: liuht@ral.neu.edu.cn; Wang, Yin-Ping; Wang, Guo-Dong

    2017-03-15

    A 0.1 mm-thick grain-oriented silicon steel sheet was successfully produced using strip casting and three-stage cold rolling method. The microstructure, texture and inhibitor evolution during the processing was briefly analyzed. It was found that Goss texture was absent in the hot rolled sheet because of the lack of shear deformation. After normalizing, a large number of dispersed MnS precipitates with the size range of 15–90 nm were produced. During first cold rolling, dense shear bands were generated in the deformed ferrite grains, resulting in the intense Goss texture after first intermediate annealing. The microstructure was further refined and homogenized during the subsequent cold rolling and annealing processes. After primary recrystallization annealing, a homogeneous microstructure consisting of fine and equiaxed grains was produced while the associated texture was characterized by a strong γ-fiber texture. Finally, a complete secondary recrystallization microstructure consisting of entirely large Goss grains was produced. The magnetic induction B{sub 8} and iron loss P{sub 10/400} was 1.79 T and 6.9 W/kg, respectively. - Highlights: • Ultra-thin grain-oriented silicon steel was produced by strip casting process. • Microstructure, texture and inhibitor evolution was briefly investigated. • Goss texture was absent in primary recrystallization annealed sheet. • MnS precipitates with a size range of 15–90 nm formed after normalizing. • A complete secondary recrystallization microstructure was produced.

  10. Nitrogen-doped biomass-based ultra-thin carbon nanosheets with interconnected framework for High-Performance Lithium-Ion Batteries

    Science.gov (United States)

    Guo, Shasha; Chen, Yaxin; Shi, Liluo; Dong, Yue; Ma, Jing; Chen, Xiaohong; Song, Huaihe

    2018-04-01

    In this paper, a low-cost and environmental friendly synthesis strategy is proposed to fabricate nitrogen-doped biomass-based ultra-thin carbon nanosheets (N-CNS) with interconnected framework by using soybean milk as the carbon precursor and sodium chloride as the template. The interconnected porous nanosheet structure is beneficial for lithium ion transportation, and the defects introduced by pyridine nitrogen doping are favorable for lithium storage. When used as the anodes for lithium-ion batteries, the N-CNS electrode shows a high initial reversible specific capacity of 1334 mAh g-1 at 50 mA g-1, excellent rate performance (1212, 555 and 336 mAh g-1 at 0.05, 0.5 and 2 A g-1, respectively) and good cycling stability (355 mAh g-1 at 1 A g-1 after 1000 cycles). Furthermore, this study demonstrates the prospects of biomass and soybean milk, as the potential anode for the application of electrochemical energy storage devices.

  11. Quantitative measurement of mean inner potential and specimen thickness from high-resolution off-axis electron holograms of ultra-thin layered WSe{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Winkler, Florian, E-mail: f.winkler@fz-juelich.de [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), Forschungszentrum Jülich, D-52425 Jülich (Germany); Peter Grünberg Institute 5 (PGI-5), Forschungszentrum Jülich, D-52425 Jülich (Germany); Tavabi, Amir H. [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), Forschungszentrum Jülich, D-52425 Jülich (Germany); Peter Grünberg Institute 5 (PGI-5), Forschungszentrum Jülich, D-52425 Jülich (Germany); Barthel, Juri [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), Forschungszentrum Jülich, D-52425 Jülich (Germany); Gemeinschaftslabor für Elektronenmikroskopie (GFE), RWTH Aachen University, D-52074 Aachen (Germany); Duchamp, Martial [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), Forschungszentrum Jülich, D-52425 Jülich (Germany); Peter Grünberg Institute 5 (PGI-5), Forschungszentrum Jülich, D-52425 Jülich (Germany); Yucelen, Emrah [FEI Company, Achtseweg Noord 5, Eindhoven 5600 KA (Netherlands); Borghardt, Sven; Kardynal, Beata E. [Peter Grünberg Institute 9 (PGI-9), Forschungszentrum Jülich, D-52425 Jülich (Germany); and others

    2017-07-15

    The phase and amplitude of the electron wavefunction that has passed through ultra-thin flakes of WSe{sub 2} is measured from high-resolution off-axis electron holograms. Both the experimental measurements and corresponding computer simulations are used to show that, as a result of dynamical diffraction, the spatially averaged phase does not increase linearly with specimen thickness close to an [001] zone axis orientation even when the specimen has a thickness of only a few layers. It is then not possible to infer the local specimen thickness of the WSe{sub 2} from either the phase or the amplitude alone. Instead, we show that the combined analysis of phase and amplitude from experimental measurements and simulations allows an accurate determination of the local specimen thickness. The relationship between phase and projected potential is shown to be approximately linear for extremely thin specimens that are tilted by several degrees in certain directions from the [001] zone axis. A knowledge of the specimen thickness then allows the electrostatic potential to be determined from the measured phase. By using this combined approach, we determine a value for the mean inner potential of WSe{sub 2} of 18.9±0.8 V, which is 12% lower than the value calculated from neutral atom scattering factors. - Highlights: • Quantitative analysis of high resolution electron holograms of WSe{sub 2}. • Local specimen thickness determination and estimation of tilt angle. • Mean inner potential evaluation of WSe2 avoiding dynamical diffraction.

  12. Rapid Biochemical Mixture Screening by Three-Dimensional Patterned Multifunctional Substrate with Ultra-Thin Layer Chromatography (UTLC) and Surface Enhanced Raman Scattering (SERS).

    Science.gov (United States)

    Lee, Bi-Shen; Lin, Pi-Chen; Lin, Ding-Zheng; Yen, Ta-Jen

    2018-01-11

    We present a three-dimensional patterned (3DP) multifunctional substrate with the functions of ultra-thin layer chromatography (UTLC) and surface enhanced Raman scattering (SERS), which simultaneously enables mixture separation, target localization and label-free detection. This multifunctional substrate is comprised of a 3DP silicon nanowires array (3DP-SiNWA), decorated with silver nano-dendrites (AgNDs) atop. The 3DP-SiNWA is fabricated by a facile photolithographic process and low-cost metal assisted chemical etching (MaCE) process. Then, the AgNDs are decorated onto 3DP-SiNWA by a wet chemical reduction process, obtaining 3DP-AgNDs@SiNWA multifunctional substrates. With various patterns designed on the substrates, the signal intensity could be maximized by the excellent confinement and concentrated effects of patterns. By using this 3DP-AgNDs@SiNWA substrate to scrutinize the mixture of two visible dyes, the individual target could be recognized and further boosted the Raman signal of target 15.42 times comparing to the un-patterned AgNDs@SiNWA substrate. Therefore, such a three-dimensional patterned multifunctional substrate empowers rapid mixture screening, and can be readily employed in practical applications for biochemical assays, food safety and other fields.

  13. Quantitative measurement of mean inner potential and specimen thickness from high-resolution off-axis electron holograms of ultra-thin layered WSe2.

    Science.gov (United States)

    Winkler, Florian; Tavabi, Amir H; Barthel, Juri; Duchamp, Martial; Yucelen, Emrah; Borghardt, Sven; Kardynal, Beata E; Dunin-Borkowski, Rafal E

    2017-07-01

    The phase and amplitude of the electron wavefunction that has passed through ultra-thin flakes of WSe 2 is measured from high-resolution off-axis electron holograms. Both the experimental measurements and corresponding computer simulations are used to show that, as a result of dynamical diffraction, the spatially averaged phase does not increase linearly with specimen thickness close to an [001] zone axis orientation even when the specimen has a thickness of only a few layers. It is then not possible to infer the local specimen thickness of the WSe 2 from either the phase or the amplitude alone. Instead, we show that the combined analysis of phase and amplitude from experimental measurements and simulations allows an accurate determination of the local specimen thickness. The relationship between phase and projected potential is shown to be approximately linear for extremely thin specimens that are tilted by several degrees in certain directions from the [001] zone axis. A knowledge of the specimen thickness then allows the electrostatic potential to be determined from the measured phase. By using this combined approach, we determine a value for the mean inner potential of WSe 2 of 18.9±0.8V, which is 12% lower than the value calculated from neutral atom scattering factors. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  14. Ultra-thin MoS2 coated Ag@Si nanosphere arrays as efficient and stable photocathode for solar-driven hydrogen production.

    Science.gov (United States)

    Zhou, Qingwei; Su, Shaoqiang; Hu, Die; Lin, Lin; Yan, Zhibo; Gao, Xingsen; Zhang, Zhang; Liu, Junming

    2018-01-02

    Solar-driven photoelectrochemical (PEC) water splitting has recently attracted much attention. Silicon (Si) is an ideal light absorber for solar energy conversion. However, the poor stability and inefficient surface catalysis of Si photocathode for hydrogen evolution reaction (HER) have been remained as the key challenges. Alternatively, MoS2 has been reported to exhibit the excellent catalysis performance if sufficient active sites for the HER are available. Here, ultra-thin MoS2 nanoflakes are directly synthesized to coat on the arrays of Ag-core Si-shell nanospheres (Ag@Si NSs) using the chemical vapor deposition (CVD). Due to the high surface area ratio and large curvature of these NSs, the as-grown MoS2 nanoflakes can accommodate more active sites. Meanwhile, the high-quality coating of MoS2 nanoflakes on the Ag@Si NSs protects the photocathode from damage during the PEC reaction. A high efficiency with a photocurrent of 33.3 mA cm-2 at a voltage of -0.4 V vs. the reversible hydrogen electrode is obtained. The as-prepared nanostructure as hydrogen photocathode is evidenced to have high stability over 12 hour PEC performance. This work opens opportunities for composite photocathode with high activity and stability using cheap and stable co-catalysts. © 2017 IOP Publishing Ltd.

  15. Innovative Method for Automatic Shape Generation and 3D Printing of Reduced-Scale Models of Ultra-Thin Concrete Shells

    Directory of Open Access Journals (Sweden)

    Ana Tomé

    2018-02-01

    Full Text Available A research and development project has been conducted aiming to design and produce ultra-thin concrete shells. In this paper, the first part of the project is described, consisting of an innovative method for shape generation and the consequent production of reduced-scale models of the selected geometries. First, the shape generation is explained, consisting of a geometrically nonlinear analysis based on the Finite Element Method (FEM to define the antifunicular of the shell’s deadweight. Next, the scale model production is described, consisting of 3D printing, specifically developed to evaluate the aesthetics and visual impact, as well as to study the aerodynamic behaviour of the concrete shells in a wind tunnel. The goals and constraints of the method are identified and a step-by-step guidelines presented, aiming to be used as a reference in future studies. The printed geometry is validated by high-resolution assessment achieved by photogrammetry. The results are compared with the geometry computed through geometric nonlinear finite-element-based analysis, and no significant differences are recorded. The method is revealed to be an important tool for automatic shape generation and building scale models of shells. The latter enables the performing of wind tunnel tests to obtain pressure coefficients, essential for structural analysis of this type of structures.

  16. Ultra-Thin Multi-Band Polarization-Insensitive Microwave Metamaterial Absorber Based on Multiple-Order Responses Using a Single Resonator Structure

    Directory of Open Access Journals (Sweden)

    Yong Zhi Cheng

    2017-10-01

    Full Text Available We design an ultra-thin multi-band polarization-insensitive metamaterial absorber (MMA using a single circular sector resonator (CSR structure in the microwave region. Simulated results show that the proposed MMA has three distinctive absorption peaks at 3.35 GHz, 8.65 GHz, and 12.44 GHz, with absorbance of 98.8%, 99.7%, and 98.3%, respectively, which agree well with an experiment. Simulated surface current distributions of the unit-cell structure reveal that the triple-band absorption mainly originates from multiple-harmonic magnetic resonance. The proposed triple-band MMA can remain at a high absorption level for all polarization of both transverse-electric (TE and transverse-magnetic (TM modes under normal incidence. Moreover, by further optimizing the geometric parameters of the CSRs, four-band and five-band MMAs can also be obtained. Thus, our design will have potential application in detection, sensing, and stealth technology.

  17. Improved integration of ultra-thin high-k dielectrics in few-layer MoS2 FET by remote forming gas plasma pretreatment

    Science.gov (United States)

    Wang, Xiao; Zhang, Tian-Bao; Yang, Wen; Zhu, Hao; Chen, Lin; Sun, Qing-Qing; Zhang, David Wei

    2017-01-01

    The effective and high-quality integration of high-k dielectrics on two-dimensional (2D) crystals is essential to the device structure engineering and performance improvement of field-effect transistor (FET) based on the 2D semiconductors. We report a 2D MoS2 transistor with ultra-thin Al2O3 top-gate dielectric (6.1 nm) and extremely low leakage current. Remote forming gas plasma pretreatment was carried out prior to the atomic layer deposition, providing nucleation sites with the physically adsorbed ions on the MoS2 surface. The top gate MoS2 FET exhibited excellent electrical performance, including high on/off current ratio over 109, subthreshold swing of 85 mV/decade and field-effect mobility of 45.03 cm2/V s. Top gate leakage current less than 0.08 pA/μm2 at 4 MV/cm has been obtained, which is the smallest compared with the reported top-gated MoS2 transistors. Such an optimized integration of high-k dielectric in 2D semiconductor FET with enhanced performance is very attractive, and it paves the way towards the realization of more advanced 2D nanoelectronic devices and integrated circuits.

  18. Fabricating high-energy quantum dots in ultra-thin LiFePO4 nanosheets using a multifunctional high-energy biomolecule-ATP

    DEFF Research Database (Denmark)

    Zhang, X.D.; Bi, Z.Y.; He, W.

    2014-01-01

    By using a multifunctional high-energy biomolecule—adenosine triphosphate (ATP)—we fabricated highenergy quantum dots (HEQDs) with a feature size of less than 10 nm and used them in high-power lithium-ion batteries. We introduced high-energy phosphate bonds into the crystal structure of LiFePO4...... nanoparticles and synthesized the mesoporous biocarbon nanowire coated LiFePO4 with HEQDs (MBCNW-LFP-HEQDs) by using ATP as a phosphorus source, a nucleating agent, a structural template and a biocarbon source. HEGDs were homogeneously formed inside the ultra-thin LiFePO4 nanosheet and the mesoporous biocarbon...... nanowire network structure was coated on the surface of the nanosheet. In LiFePO4 nanoparticles, HEQDs result in more storage sites of Li+ ions and easier transfer kinetics of electrons and lithium ions, where the kinetic transformation path between LiFePO4 and FePO4 is rather different from the path...

  19. Thin NbN film structures on SOI for SNSPD

    Energy Technology Data Exchange (ETDEWEB)

    Il' in, Konstantin; Kurz, Stephan; Henrich, Dagmar; Hofherr, Matthias; Siegel, Michael [IMS, KIT, Karlsruhe (Germany); Semenov, Alexei; Huebers, Heinz-Wilhelm [DLR, Berlin (Germany)

    2012-07-01

    Superconducting Nanowire Single-Photon Detectors (SNSPD) made from ultra-thin NbN films on sapphire demonstrate almost 100% intrinsic detection efficiency (DE). However the system DE values is less than 10% mostly limited by a very low absorptance of NbN films thinner than 5 nm. Integration of SNSPD in Si photonic circuit is a promising way to overcome this problem. We present results on optimization of technology of thin NbN film nanostructures on SOI (Silicon on Insulator) substrate used in Si photonics technology. Superconducting and normal state properties of these structures important for SNSPD development are presented and discussed.

  20. An investigation into which factors control the nanotribological behaviour of thin sputtered carbon films

    International Nuclear Information System (INIS)

    Shi Baogui; Sullivan, John L; Beake, Ben D

    2008-01-01

    Ultra-thin (20-100 nm) films deposited on Si surfaces can improve their mechanical and tribological properties. As a stepping stone towards the optimization of such ultra-thin films, herein we report experimental nanoscratch and nanowear data on a-C films of thickness in the range 200-1000 nm on Si aiming to (1) understand the role of film thickness on the nanoscratch behaviour, (2) determine whether the same factors (substrate bias, H/E ratio, etc) are at play for thick films as for the thin films, (3) determine possible design rules for thinner films enabling their optimization for MEMS applications and (4) evaluate the use of the multi-pass (3-scan) procedure for clarifying the locus of failure. To a first approximation, the critical load for total film failure in the nanoscratch test is proportional to thickness provided the films are not too stressed. a-C films of 1 μm with very high H/E, deposited under high substrate bias, perform well at low load but very poorly in more highly loaded situations. Not only do they exhibit low critical loads but also failure involves extensive delamination outside of the scratch track. This is not observed on thinner films. A suitable strategy for optimizing wear resistance for thin films for MEMS applications is to aim to maximize H/E. For the 200 nm films studied here, the films with the highest H/E showed slightly improved scratch resistance

  1. Preparation and characterization of flexible asymmetric supercapacitors based on transition-metal-oxide nanowire/single-walled carbon nanotube hybrid thin-film electrodes.

    Science.gov (United States)

    Chen, Po-Chiang; Shen, Guozhen; Shi, Yi; Chen, Haitian; Zhou, Chongwu

    2010-08-24

    In the work described in this paper, we have successfully fabricated flexible asymmetric supercapacitors (ASCs) based on transition-metal-oxide nanowire/single-walled carbon nanotube (SWNT) hybrid thin-film electrodes. These hybrid nanostructured films, with advantages of mechanical flexibility, uniform layered structures, and mesoporous surface morphology, were produced by using a filtration method. Here, manganese dioxide nanowire/SWNT hybrid films worked as the positive electrode, and indium oxide nanowire/SWNT hybrid films served as the negative electrode in a designed ASC. In our design, charges can be stored not only via electrochemical double-layer capacitance from SWNT films but also through a reversible faradic process from transition-metal-oxide nanowires. In addition, to obtain stable electrochemical behavior during charging/discharging cycles in a 2 V potential window, the mass balance between two electrodes has been optimized. Our optimized hybrid nanostructured ASCs exhibited a superior device performance with specific capacitance of 184 F/g, energy density of 25.5 Wh/kg, and columbic efficiency of approximately 90%. In addition, our ASCs exhibited a power density of 50.3 kW/kg, which is 10-fold higher than obtained in early reported ASC work. The high-performance hybrid nanostructured ASCs can find applications in conformal electrics, portable electronics, and electrical vehicles.

  2. Pure crystal orientation and anisotropic charge transport in large-area hybrid perovskite films

    KAUST Repository

    Cho, Nam Chul; Li, Feng; Turedi, Bekir; Sinatra, Lutfan; Sarmah, Smritakshi P.; Parida, Manas R.; Saidaminov, Makhsud I.; Banavoth, Murali; Burlakov, Victor M.; Goriely, Alain; Mohammed, Omar F.; Wu, Tao; Bakr, Osman

    2016-01-01

    Controlling crystal orientations and macroscopic morphology is vital to develop the electronic properties of hybrid perovskites. Here we show that a large-area, orientationally pure crystalline (OPC) methylammonium lead iodide (MAPbI3) hybrid

  3. Ultra-thin solution-based coating of molybdenum oxide on multiwall carbon nanotubes for high-performance supercapacitor electrodes

    KAUST Repository

    Shakir, Imran

    2014-02-01

    Uniform and conformal coating of ultrathin molybdenum oxide (MoO 3) thin film onto conducting MWCNTs was successfully synthesized through a facile, nontoxic and generally applicable precipitation method, followed by a simple heat treatment. The ultrathin MoO3 coating enables a fast and reversible redox reaction which improves the specific capacitance by utilizing the maximum number of active sites for the redox reaction, while the high porosity of the MWCNTs facilitates ion migration in the electrolyte and shorten the ion diffusion path. The ultrathin MoO3 coated MWCNTs electrodes show a very high specific capacitance of 1145 Fg -1 in 2 M Na2SO4 aqueous solution when 5 nm thick MoO3 was considered alone despite the low weight percentage of the MoO3 (16wt%). Furthermore, the ultrathin MoO3 coated MWCNTs supercapacitor electrodes exhibited excellent cycling performance of > 97% capacitance retention over 1000 cycles. © 2013 Elsevier Ltd.

  4. Hybrid thin-film solar cells comprising mesoporous titanium dioxide and conjugated polymers; Hybride Duennschicht-Solarzellen aus mesoporoesem Titandioxid und konjugierten Polymeren

    Energy Technology Data Exchange (ETDEWEB)

    Schattauer, Sylvia

    2010-12-01

    The main objective of this thesis is to study the active components and their interactions in so called organic hybrid solar cells. These consist of a thin inorganic titanium dioxide layer, combined with a polymer layer. In general, the efficiency of these hybrid solar cells is determined by the light absorption in the donor polymer, the dissociation of excitons at the heterojunction between TiO{sub 2} and polymer, as well as the generation and extraction of free charge carriers. To optimize the solar cells, the physical interactions between the materials are modified and the influences of various preparation parameters are systematically investigated. Among others, important findings regarding the optimal use of materials and preparation conditions as well as detailed investigations of fundamental factors such as film morphology and polymer infiltration are presented in more detail. First, a variety of titanium dioxide layer were produced, from which a selection for use in hybrid solar cells was made. The obtained films show differences in surface structure, film morphology and crystallinity, depending on the way how the TiO{sub 2} layer has been prepared. All these properties of the TiO{sub 2} films may strongly affect the performance of the hybrid solar cells, by influencing e.g. the exciton diffusion length, the efficiency of exciton dissociation at the hybrid interface, and the carrier transport properties. Detailed investigations were made for mesoporous TiO{sub 2} layer following a new nanoparticle synthesis route, which allows to produce crystalline particles during the synthesis. As donor component, conjugated polymers, either derivatives of cyclohexylamino-poly(p-phenylene vinylene) (PPV) or a thiophene are used. The preparation routine also includes a thermal treatment of the TiO{sub 2} layers, revealing a temperature-dependent change in morphology, but not of the crystal structure. The effects on the solar cell properties have been documented and

  5. Structural properties and surface wettability of Cu-containing diamond-like carbon films prepared by a hybrid linear ion beam deposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Peng; Sun, Lili; Li, Xiaowei [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Xu, Sheng [Gao Hong Coating Technology Co., Ltd, Huzhou 313000 (China); Ke, Peiling [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Wang, Aiying, E-mail: aywang@nimte.ac.cn [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)

    2015-06-01

    Cu-containing diamond-like carbon (Cu-DLC) films were deposited on Si/glass substrate by a hybrid ion beam deposition system. The Cu concentration (0.1–39.7 at.%) in the film was controlled by varying the sputtering current. The microstructure and composition of Cu-DLC films were investigated systematically. The surface topography, roughness and surface wettability of the films were also studied. Results indicated that with increasing the Cu concentration, the water contact angle of the films changed from 66.8° for pure carbon film to more than 104.4° for Cu-DLC films with Cu concentration larger than 24.4 at.%. In the hydrophilic region, the polar surface energy decreased from 30.54 mJ/m{sup 2} for pure carbon film to 2.48 mJ/m{sup 2} for the film with Cu 7.0 at.%. - Highlights: • Cu-containing diamond-like carbon (DLC) films were deposited by a hybrid ion beam system. • Cu-containing DLC films exhibited a wide range of water contact angle. • The water contact angles vary with the surface energies and surface roughness.

  6. Facile fabrication of nano-structured silica hybrid film with superhydrophobicity by one-step VAFS approach

    Science.gov (United States)

    Jia, Yi; Yue, Renliang; Liu, Gang; Yang, Jie; Ni, Yong; Wu, Xiaofeng; Chen, Yunfa

    2013-01-01

    Here we report a novel one-step vapor-fed aerosol flame synthesis (VAFS) method to attain silica hybrid film with superhydrophobicity on normal glass and other engineering material substrates using hexamethyldisiloxane (HMDSO) as precursor. The deposited nano-structured silica films represent excellent superhydrophobicity with contact angle larger than 150° and sliding angle below 5°, without any surface modification or other post treatments. SEM photographs proved that flame-made SiO2 nanoparticles formed dual-scale surface roughness on the substrates. It was confirmed by FTIR and XPS that the in situ formed organic fragments on the particle surface as species like (CH3)xSiO2-x/2 (x = 1, 2, 3) which progressively lowered the surface energy of fabricated films. Thus, these combined dual-scale roughness and lowered surface energy cooperatively produced superhydrophobic films. IR camera had been used to monitor the real-time flame temperature. It is found that the inert dilution gas inflow played a critical role in attaining superhydrophobicity due to its cooling and anti-oxidation effect. This method is facile and scalable for diverse substrates, without any requirement of complex equipments and multiple processing steps. It may contribute to the industrial fabrication of superhydrophobic films.

  7. Dielectric relaxation and ac conductivity behaviour of polyvinyl alcohol–HgSe quantum dot hybrid films

    International Nuclear Information System (INIS)

    Sinha, Subhojyoti; Chatterjee, Sanat Kumar; Meikap, Ajit Kumar; Ghosh, Jiten

    2014-01-01

    Here we report a comparative study on the dielectric relaxation and ac conductivity behaviour of pure polyvinyl alcohol (PVA) and PVA–mercury selenide (HgSe) quantum dot hybrid films in the temperature range 298 K ⩽ T ⩽ 420 K and in the frequency range 100 Hz ⩽ f ⩽ 1 MHz. The prepared nanocomposite exhibits a larger dielectric constant as compared to the pure PVA. The real and imaginary parts of the dielectric constants were found to fit appreciably with the modified Cole–Cole equation, from which temperature-dependent values of the relaxation times, free charge carrier conductivity and space charge carrier conductivity were calculated. The relaxation time decreases with the quantum dot's inclusion in the PVA matrix and with an increase in temperature, whereas free charge carrier conductivity and space charge carrier conductivity increases with an increase in temperature. An increase in ac conductivity for the nanocomposites has also been observed, while the charge transport mechanism was found to follow the correlated barrier hopping model in both cases. An easy-path model with a suitable electrical equivalent circuit has been employed to analyse the temperature-dependent impedance spectra. The imaginary part of the complex electric modulus spectra exhibit an asymmetric nature and a non-Debye type of behaviour, which has been elucidated considering a generalized susceptibility function. The electric modulus spectra of the nanocomposite demonstrate a smaller amplitude and broader width, as compared to the pure PVA sample. (paper)

  8. CdO nanosheet film with a (200)-preferred orientation with sensitivity to liquefied petroleum gas (LPG) at low-temperatures.

    Science.gov (United States)

    Cui, Guangliang; Li, Zimeng; Gao, Liang; Zhang, Mingzhe

    2012-12-21

    CdO nanosheet film can be synthesized by electrochemical deposition in an ultra-thin liquid layer by using Cd(NO(3))(2) and HNO(3) as source materials for Cd and oxygen respectively. HNO(3) is also used to adjust the pH of the electrolyte. Studies on the detailed structure indicate that the synthesized CdO nanosheet film has a face-centered cubic structure with (200)-preferred orientation. The response of the CdO nanosheet film to liquefied petroleum gas (LPG) at low temperature has been significantly improved by the novel structure of film. It has exhibited excellent sensitivity and selectivity to LPG at low temperature. A new growth mechanism of electrochemical deposition has been proposed to elaborate the formation of nanosheet in an ultra-thin liquid layer. The self-oscillation of potential in the growth interface and intermediate hydroxide are responsible for the formation of nanosheets.

  9. Synthesis of aluminum nitride films by plasma immersion ion implantation-deposition using hybrid gas-metal cathodic arc gun

    International Nuclear Information System (INIS)

    Shen Liru; Fu, Ricky K.Y.; Chu, Paul K.

    2004-01-01

    Aluminum nitride (AlN) is of interest in the industry because of its excellent electronic, optical, acoustic, thermal, and mechanical properties. In this work, aluminum nitride films are deposited on silicon wafers (100) by metal plasma immersion ion implantation and deposition (PIIID) using a modified hybrid gas-metal cathodic arc plasma source and with no intentional heating to the substrate. The mixed metal and gaseous plasma is generated by feeding the gas into the arc discharge region. The deposition rate is found to mainly depend on the Al ion flux from the cathodic arc source and is only slightly affected by the N 2 flow rate. The AlN films fabricated by this method exhibit a cubic crystalline microstructure with stable and low internal stress. The surface of the AlN films is quite smooth with the surface roughness on the order of 1/2 nm as determined by atomic force microscopy, homogeneous, and continuous, and the dense granular microstructures give rise to good adhesion with the substrate. The N to Al ratio increases with the bias voltage applied to the substrates. A fairly large amount of O originating from the residual vacuum is found in the samples with low N:Al ratios, but a high bias reduces the oxygen concentration. The compositions, microstructures and crystal states of the deposited films are quite stable and remain unchanged after annealing at 800 deg. C for 1 h. Our hybrid gas-metal source cathodic arc source delivers better AlN thin films than conventional PIIID employing dual plasmas

  10. Free-Standing and Self-Crosslinkable Hybrid Films by Core–Shell Particle Design and Processing

    Directory of Open Access Journals (Sweden)

    Steffen Vowinkel

    2017-11-01

    Full Text Available The utilization and preparation of functional hybrid films for optical sensing applications and membranes is of utmost importance. In this work, we report the convenient and scalable preparation of self-crosslinking particle-based films derived by directed self-assembly of alkoxysilane-based cross-linkers as part of a core-shell particle architecture. The synthesis of well-designed monodisperse core-shell particles by emulsion polymerization is the basic prerequisite for subsequent particle processing via the melt-shear organization technique. In more detail, the core particles consist of polystyrene (PS or poly(methyl methacrylate (PMMA, while the comparably soft particle shell consists of poly(ethyl acrylate (PEA and different alkoxysilane-based poly(methacrylates. For hybrid film formation and convenient self-cross-linking, different alkyl groups at the siloxane moieties were investigated in detail by solid-state Magic-Angle Spinning Nuclear Magnetic Resonance (MAS, NMR spectroscopy revealing different crosslinking capabilities, which strongly influence the properties of the core or shell particle films with respect to transparency and iridescent reflection colors. Furthermore, solid-state NMR spectroscopy and investigation of the thermal properties by differential scanning calorimetry (DSC measurements allow for insights into the cross-linking capabilities prior to and after synthesis, as well as after the thermally and pressure-induced processing steps. Subsequently, free-standing and self-crosslinked particle-based films featuring excellent particle order are obtained by application of the melt-shear organization technique, as shown by microscopy (TEM, SEM.

  11. Particle Induced X-ray Emission (PIXE) Approach for the Quantification of Thin Al Films

    International Nuclear Information System (INIS)

    Younes, G; Zahraman, K; Nsouli, B; Soueidan, M; Ferro, G

    2008-01-01

    Particle Induced X-ray Emission (PIXE) has been used as a fast and non-destructive technique for sensitive characterization of ultra thin Al films deposited by evaporation onto Si substrate. In this work the PIXE technique was optimized, using proton beam at different energies and different angles of incidence, for the characterization of ultra thin Al films (few nanometers) deposited onto Si substrate. The PIXE results showed that a proton beam of 300 keV under tilting angle of 80 degree permits an accurate determination of Al with high sensitivity within few minutes of acquisition time and a LOD of less than 0.2 nm. The LOD versus energy and tilting angle will be presented and discussed. (author)

  12. Organic photovoltaics using thin gold film as an alternative anode to indium tin oxide

    International Nuclear Information System (INIS)

    Haldar, Amrita; Yambem, Soniya D.; Liao, Kang-Shyang; Alley, Nigel J.; Dillon, Eoghan P.; Barron, Andrew R.; Curran, Seamus A.

    2011-01-01

    Indium Tin Oxide (ITO) is the most commonly used anode as a transparent electrode and more recently as an anode for organic photovoltaics (OPVs). However, there are significant drawbacks in using ITO which include high material costs, mechanical instability including brittleness and poor electrical properties which limit its use in low-cost flexible devices. We present initial results of poly(3-hexylthiophene): phenyl-C 61 -butyric acid methyl ester OPVs showing that an efficiency of 1.9% (short-circuit current 7.01 mA/cm 2 , open-circuit voltage 0.55 V, fill factor 0.49) can be attained using an ultra thin film of gold coated glass as the device anode. The initial I-V characteristics demonstrate that using high work function metals when the thin film is kept ultra thin can be used as a replacement to ITO due to their greater stability and better morphological control.

  13. Large-scale complementary macroelectronics using hybrid integration of carbon nanotubes and IGZO thin-film transistors.

    Science.gov (United States)

    Chen, Haitian; Cao, Yu; Zhang, Jialu; Zhou, Chongwu

    2014-06-13

    Carbon nanotubes and metal oxide semiconductors have emerged as important materials for p-type and n-type thin-film transistors, respectively; however, realizing sophisticated macroelectronics operating in complementary mode has been challenging due to the difficulty in making n-type carbon nanotube transistors and p-type metal oxide transistors. Here we report a hybrid integration of p-type carbon nanotube and n-type indium-gallium-zinc-oxide thin-film transistors to achieve large-scale (>1,000 transistors for 501-stage ring oscillators) complementary macroelectronic circuits on both rigid and flexible substrates. This approach of hybrid integration allows us to combine the strength of p-type carbon nanotube and n-type indium-gallium-zinc-oxide thin-film transistors, and offers high device yield and low device variation. Based on this approach, we report the successful demonstration of various logic gates (inverter, NAND and NOR gates), ring oscillators (from 51 stages to 501 stages) and dynamic logic circuits (dynamic inverter, NAND and NOR gates).

  14. Fabrication of Ultra-Thin Printed Organic TFT CMOS Logic Circuits Optimized for Low-Voltage Wearable Sensor Applications.

    Science.gov (United States)

    Takeda, Yasunori; Hayasaka, Kazuma; Shiwaku, Rei; Yokosawa, Koji; Shiba, Takeo; Mamada, Masashi; Kumaki, Daisuke; Fukuda, Kenjiro; Tokito, Shizuo

    2016-05-09

    Ultrathin electronic circuits that can be manufactured by using conventional printing technologies are key elements necessary to realize wearable health sensors and next-generation flexible electronic devices. Due to their low level of power consumption, complementary (CMOS) circuits using both types of semiconductors can be easily employed in wireless devices. Here, we describe ultrathin CMOS logic circuits, for which not only the source/drain electrodes but also the semiconductor layers were printed. Both p-type and n-type organic thin film transistor devices were employed in a D-flip flop circuit in the newly developed stacked structure and exhibited excellent electrical characteristics, including good carrier mobilities of 0.34 and 0.21 cm(2) V(-1) sec(-1), and threshold voltages of nearly 0 V with low operating voltages. These printed organic CMOS D-flip flop circuits exhibit operating frequencies of 75 Hz and demonstrate great potential for flexible and printed electronics technology, particularly for wearable sensor applications with wireless connectivity.

  15. Effects of DC gate and drain bias stresses on the degradation of excimer laser crystallized polysilicon thin film transistors

    International Nuclear Information System (INIS)

    Kouvatsos, D N; Michalas, L; Voutsas, A T; Papaioannou, G J

    2005-01-01

    The effects of gate and drain bias stresses on thin film transistors fabricated in polysilicon films crystallized using the advanced sequential lateral solidification excimer laser annealing (SLS ELA) process, which yields very elongated polysilicon grains and allows the fabrication of TFTs without grain boundary barriers to current flow, are investigated as a function of the active layer thickness and of the TFT orientation relative to the grains. The application of hot carrier stress, with a condition of V GS = V DS /2, was determined to induce threshold voltage, subthreshold swing and transconductance degradation for TFTs in thicker polysilicon films and the associated stress-induced increase in the active layer trap density was evaluated. However, this device degradation was drastically reduced for TFTs fabricated in ultra-thin films. Furthermore, the application of the same stress condition to TFTs oriented vertically to the elongated grains resulted in similar threshold voltage shift but in substantially decreased subthreshold swing and transconductance degradation. The immunity of ultra-thin active layer devices to degradation under hot carrier stress clearly suggests the implementation of ultra thin SLS ELA polysilicon films for the fabrication of TFTs exhibiting not only high performance but, especially, the high reliability needed for integrated systems on panel

  16. Degradation of TiO2 and/or SiO2 hybrid films doped with different cationic dyes

    International Nuclear Information System (INIS)

    Purcar, Violeta; Caprarescu, Simona; Donescu, Dan; Petcu, Cristian; Stamatin, Ioan; Ianchis, Raluca; Stroescu, Hermine

    2013-01-01

    Hybrid thin films, silica–titanium oxides and silica–aluminum oxides, designed based on the sol–gel process are evaluated as catalysts in the photo-degradation of the cationic dyes. Silica matrices from different precursors with various organic functional groups and cross-linked with titanium or aluminum agents (tetraisopropyl orthotitanate and aluminum sec-butoxide) allow the surface property tailoring related to the high capacity of the dye adsorption respective, high photo-degradation activity. The cationic dyes (methylene blue, rhodamine B, crystal violet, malachite green) embedded on the hybrid silica matrix, under ultraviolet light, have a first order kinetics of photodegradation. The cross-linking agents play a key role in the photocatalytic degradation and silica matrix as dye absorbent. The photo-degradation rate for the binary system derived from methyltriethoxysilane/vinyltriethoxysilane precursors with both cross linkers showed a significant improvement by comparison with other hybrid materials. The significant increasing in the photodecomposition rate is related to the capacity to generate additional oxidizing species by each silica hybrid compounds. - Highlights: ► Dyes display different electrostatic interactions to the silica matrix. ► Cross-linking agent influences the photocatalytic degradation of dyes. ► Photodegradation reaction obeyed the rules of a pseudo-first-order kinetic reaction. ► UV radiation can be the origin of the photodegradation

  17. A hybrid tandem solar cell based on hydrogenated amorphous silicon and dye-sensitized TiO{sub 2} film

    Energy Technology Data Exchange (ETDEWEB)

    Hao Sancun [Institute of Materials Physical Chemistry, Huaqiao University, Quanzhou, 362021 (China); Institute of Photo-Electronics of Nankai University, Tianjin 300071 (China); Jiangsu Shuangdeng Group Co. Ltd, Thaizhou, Jiangsu, 225526 (China); Wu Jihuai, E-mail: jhwu@hqu.edu.cn [Institute of Materials Physical Chemistry, Huaqiao University, Quanzhou, 362021 (China); Sun Zhonglin [Institute of Photo-Electronics of Nankai University, Tianjin 300071 (China)

    2012-01-01

    Hydrogenated amorphous silicon film (a-Si:H) as top cell is introduced to dye-sensitized titanium dioxide nanocrystalline solar cell (DSSC) as bottom cell to assemble a hybrid tandem solar cell. The hybrid tandem solar cell fabricated with the thicknesses a-Si:H layer of 235 nm, ZnO/Pt interlayer of 100 nm and DSSC layer of 8.5 {mu}m achieves a photo-to-electric energy conversion efficiency of 8.31%, a short circuit current density of 10.61 mA{center_dot}cm{sup -2} and an open-circuit voltage of 1.45 V under a simulated solar light irradiation of 100 mW{center_dot}cm{sup -2}.

  18. General Space-Confined On-Substrate Fabrication of Thickness-Adjustable Hybrid Perovskite Single-Crystalline Thin Films.

    Science.gov (United States)

    Chen, Yao-Xuan; Ge, Qian-Qing; Shi, Yang; Liu, Jie; Xue, Ding-Jiang; Ma, Jing-Yuan; Ding, Jie; Yan, Hui-Juan; Hu, Jin-Song; Wan, Li-Jun

    2016-12-21

    Organic-inorganic hybrid perovskite single-crystalline thin films (SCTFs) are promising for enhancing photoelectric device performance due to high carrier mobility, long diffusion length, and carrier lifetime. However, bulk perovskite single crystals available today are not suitable for practical device application due to the unfavorable thickness. Herein, we report a facile space-confined solution-processed strategy to on-substrate grow various hybrid perovskite SCTFs in a size of submillimeter with adjustable thicknesses from nano- to micrometers. These SCTFs exhibit photoelectric properties comparable to bulk single crystals with low defect density and good air stability. The clear thickness-dependent colors allow fast visual selection of SCTFs with a suitable thickness for specific device application. The present substrate-independent growth of perovskite SCTFs opens up opportunities for on-chip fabrication of diverse high-performance devices.

  19. Scanning electrochemical microscopy of graphene/polymer hybrid thin films as supercapacitors: Physical-chemical interfacial processes

    Directory of Open Access Journals (Sweden)

    Sanju Gupta

    2015-10-01

    Full Text Available Hybrid electrode comprising an electric double-layer capacitor of graphene nanosheets and a pseudocapacitor of the electrically conducting polymers namely, polyaniline; PAni and polypyrrole; PPy are constructed that exhibited synergistic effect with excellent electrochemical performance as thin film supercapacitors for alternative energy. The hybrid supercapacitors were prepared by layer-by-layer (LbL assembly based on controlled electrochemical polymerization followed by reduction of graphene oxide electrochemically producing ErGO, for establishing intimate electronic contact through nanoscale architecture and chemical stability, producing a single bilayer of (PAni/ErGO1, (PPy/ErGO1, (PAni/GO1 and (PPy/GO1. The rationale design is to create thin films that possess interconnected graphene nanosheets (GNS with polymer nanostructures forming well-defined tailored interfaces allowing sufficient surface adsorption and faster ion transport due to short diffusion distances. We investigated their electrochemical properties and performance in terms of gravimetric specific capacitance, Cs, from cyclic voltammograms. The LbL-assembled bilayer films exhibited an excellent Cs of ≥350 F g−1 as compared with constituents (∼70 F g−1 at discharge current density of 0.3 A g−1 that outperformed many other hybrid supercapacitors. To gain deeper insights into the physical-chemical interfacial processes occurring at the electrode/electrolyte interface that govern their operation, we have used scanning electrochemical microscopy (SECM technique in feedback and probe approach modes. We present our findings from viewpoint of reinforcing the role played by heterogeneous electrode surface composed of nanoscale graphene sheets (conducting and conducting polymers (semiconducting backbone with ordered polymer chains via higher/lower probe current distribution maps. Also targeted is SECM imaging that allowed to determine electrochemical (reactivity of surface ion

  20. Scanning electrochemical microscopy of graphene/polymer hybrid thin films as supercapacitors: Physical-chemical interfacial processes

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Sanju, E-mail: sanju.gupta@wku.edu; Price, Carson [Department of Physics and Astronomy, Western Kentucky University, 1906 College Heights Blvd., Bowling Green, KY 42101-3576 (United States)

    2015-10-15

    Hybrid electrode comprising an electric double-layer capacitor of graphene nanosheets and a pseudocapacitor of the electrically conducting polymers namely, polyaniline; PAni and polypyrrole; PPy are constructed that exhibited synergistic effect with excellent electrochemical performance as thin film supercapacitors for alternative energy. The hybrid supercapacitors were prepared by layer-by-layer (LbL) assembly based on controlled electrochemical polymerization followed by reduction of graphene oxide electrochemically producing ErGO, for establishing intimate electronic contact through nanoscale architecture and chemical stability, producing a single bilayer of (PAni/ErGO){sub 1}, (PPy/ErGO){sub 1}, (PAni/GO){sub 1} and (PPy/GO){sub 1}. The rationale design is to create thin films that possess interconnected graphene nanosheets (GNS) with polymer nanostructures forming well-defined tailored interfaces allowing sufficient surface adsorption and faster ion transport due to short diffusion distances. We investigated their electrochemical properties and performance in terms of gravimetric specific capacitance, C{sub s}, from cyclic voltammograms. The LbL-assembled bilayer films exhibited an excellent C{sub s} of ≥350 F g{sup −1} as compared with constituents (∼70 F g{sup −1}) at discharge current density of 0.3 A g{sup −1} that outperformed many other hybrid supercapacitors. To gain deeper insights into the physical-chemical interfacial processes occurring at the electrode/electrolyte interface that govern their operation, we have used scanning electrochemical microscopy (SECM) technique in feedback and probe approach modes. We present our findings from viewpoint of reinforcing the role played by heterogeneous electrode surface composed of nanoscale graphene sheets (conducting) and conducting polymers (semiconducting) backbone with ordered polymer chains via higher/lower probe current distribution maps. Also targeted is SECM imaging that allowed to determine

  1. Scanning electrochemical microscopy of graphene/polymer hybrid thin films as supercapacitors: Physical-chemical interfacial processes

    Science.gov (United States)

    Gupta, Sanju; Price, Carson

    2015-10-01

    Hybrid electrode comprising an electric double-layer capacitor of graphene nanosheets and a pseudocapacitor of the electrically conducting polymers namely, polyaniline; PAni and polypyrrole; PPy are constructed that exhibited synergistic effect with excellent electrochemical performance as thin film supercapacitors for alternative energy. The hybrid supercapacitors were prepared by layer-by-layer (LbL) assembly based on controlled electrochemical polymerization followed by reduction of graphene oxide electrochemically producing ErGO, for establishing intimate electronic contact through nanoscale architecture and chemical stability, producing a single bilayer of (PAni/ErGO)1, (PPy/ErGO)1, (PAni/GO)1 and (PPy/GO)1. The rationale design is to create thin films that possess interconnected graphene nanosheets (GNS) with polymer nanostructures forming well-defined tailored interfaces allowing sufficient surface adsorption and faster ion transport due to short diffusion distances. We investigated their electrochemical properties and performance in terms of gravimetric specific capacitance, Cs, from cyclic voltammograms. The LbL-assembled bilayer films exhibited an excellent Cs of ≥350 F g-1 as compared with constituents (˜70 F g-1) at discharge current density of 0.3 A g-1 that outperformed many other hybrid supercapacitors. To gain deeper insights into the physical-chemical interfacial processes occurring at the electrode/electrolyte interface that govern their operation, we have used scanning electrochemical microscopy (SECM) technique in feedback and probe approach modes. We present our findings from viewpoint of reinforcing the role played by heterogeneous electrode surface composed of nanoscale graphene sheets (conducting) and conducting polymers (semiconducting) backbone with ordered polymer chains via higher/lower probe current distribution maps. Also targeted is SECM imaging that allowed to determine electrochemical (re)activity of surface ion adsorption sites

  2. Fabrication of ridge waveguide structure from photosensitive TiO2/ormosil hybrid films by using an ultraviolet soft imprint technique

    International Nuclear Information System (INIS)

    Zhang, Xuehua; Que, Wenxiu; Chen, Jing; Gao, Tianxi; Hu, Jiaxing; Liu, Weiguo

    2013-01-01

    Photosensitive TiO 2 /organically modified silane hybrid films were prepared by combining a low-temperature sol–gel process with a spin-coating technique. Optical properties and photochemical activities of the as-prepared hybrid sol–gel films under different UV irradiation time were characterized and monitored by prism coupling technique, UV–visible spectroscopy, and Fourier transform infrared spectroscopy. Surface morphology of the hybrid films was also observed by an atomic force microscopy. Advantages for fabrication of ridge waveguide structure based on the photosensitive hybrid films were demonstrated by an ultraviolet soft imprint technique. Effects of imprint force, imprint time, and UV irradiation time on high replication fidelity of the ridge waveguide structure were also investigated. An altitude replication fidelity of 99.7% can be obtained when the imprint force of 2 MPa, imprint time of 30 min and UV irradiation time of 45 min were chosen. Scanning electron microscopy and surface profiler were used to characterize the morphological and surface profile properties of the as fabricated ridge waveguide structure. Results indicate that the as-prepared photosensitive hybrid materials have great applicability for the fabrication of micro-optical elements and advantage as the imprint layer under the ultraviolet soft imprint technique. - Highlights: ► Photosensitive TiO 2 /ormosil hybrid film is prepared by a sol–gel process. ► Optical properties of the