WorldWideScience

Sample records for based thin films

  1. Crystallization of zirconia based thin films.

    Science.gov (United States)

    Stender, D; Frison, R; Conder, K; Rupp, J L M; Scherrer, B; Martynczuk, J M; Gauckler, L J; Schneider, C W; Lippert, T; Wokaun, A

    2015-07-28

    The crystallization kinetics of amorphous 3 and 8 mol% yttria stabilized zirconia (3YSZ and 8YSZ) thin films grown by pulsed laser deposition (PLD), spray pyrolysis and dc-magnetron sputtering are explored. The deposited films were heat treated up to 1000 °C ex situ and in situ in an X-ray diffractometer. A minimum temperature of 275 °C was determined at which as-deposited amorphous PLD grown 3YSZ films fully crystallize within five hours. Above 325 °C these films transform nearly instantaneously with a high degree of micro-strain when crystallized below 500 °C. In these films the t'' phase crystallizes which transforms at T > 600 °C to the t' phase upon relaxation of the micro-strain. Furthermore, the crystallization of 8YSZ thin films grown by PLD, spray pyrolysis and dc-sputtering are characterized by in situ XRD measurements. At a constant heating rate of 2.4 K min(-1) crystallization is accomplished after reaching 800 °C, while PLD grown thin films were completely crystallized already at ca. 300 °C. PMID:26119755

  2. Nanocrystalline silicon based thin film solar cells

    Science.gov (United States)

    Ray, Swati

    2012-06-01

    Amorphous silicon solar cells and panels on glass and flexible substrate are commercially available. Since last few years nanocrystalline silicon thin film has attracted remarkable attention due to its stability under light and ability to absorb longer wavelength portion of solar spectrum. For amorphous silicon/ nanocrystalline silicon double junction solar cell 14.7% efficiency has been achieved in small area and 13.5% for large area modules internationally. The device quality nanocrystalline silicon films have been fabricated by RF and VHF PECVD methods at IACS. Detailed characterizations of the materials have been done. Nanocrystalline films with low defect density and high stability have been developed and used as absorber layer of solar cells.

  3. Methods for preparing colloidal nanocrystal-based thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kagan, Cherie R.; Fafarman, Aaron T.; Choi, Ji-Hyuk; Koh, Weon-kyu; Kim, David K.; Oh, Soong Ju; Lai, Yuming; Hong, Sung-Hoon; Saudari, Sangameshwar Rao; Murray, Christopher B.

    2016-05-10

    Methods of exchanging ligands to form colloidal nanocrystals (NCs) with chalcogenocyanate (xCN)-based ligands and apparatuses using the same are disclosed. The ligands may be exchanged by assembling NCs into a thin film and immersing the thin film in a solution containing xCN-based ligands. The ligands may also be exchanged by mixing a xCN-based solution with a dispersion of NCs, flocculating the mixture, centrifuging the mixture, discarding the supernatant, adding a solvent to the pellet, and dispersing the solvent and pellet to form dispersed NCs with exchanged xCN-ligands. The NCs with xCN-based ligands may be used to form thin film devices and/or other electronic, optoelectronic, and photonic devices. Devices comprising nanocrystal-based thin films and methods for forming such devices are also disclosed. These devices may be constructed by depositing NCs on to a substrate to form an NC thin film and then doping the thin film by evaporation and thermal diffusion.

  4. Linear Microbolometric Array Based on VOx Thin Film

    Science.gov (United States)

    Chen, Xi-Qu

    2010-05-01

    In this paper, a linear microbolometric array based on VOx thin film is proposed. The linear microbolometric array is fabricated by using micromachining technology, and its thermo-sensitive VOx thin film has excellent infrared response spectrum and TCR characteristics. Integrated with CMOS circuit, an experimentally prototypical monolithic linear microbolometric array is designed and fabricated. The testing results of the experimental linear array show that the responsivity of linear array can approach 18KV/W and is potential for infrared image systems.

  5. A PC based thin film dosimeter system

    DEFF Research Database (Denmark)

    Miller, A.; Hargittai, P.; Kovacs, A.

    2000-01-01

    A dosimeter system based on the Riso B3 dosimeter film, an office scanner for use with PC and the associated software is presented. The scanned image is analyzed either with standard software (Paint Shop Pro 5 or Excel) functions or with the computer code "Scanalizer" that allows presentation...

  6. Hybrid Thin Films Based Upon Polyoxometalates-Polymer Assembly

    Science.gov (United States)

    Qi, Na; Jing, Benxin; Zhu, Yingxi

    2014-03-01

    Block copolymers (BCPs) and polyoxometalates (POMs) have been used individually as building blocks for design and synthesis of novel functional materials. POM nanoclusters, the assemblies of transition metal oxides with well-defined atomic coordination structure, have been recently explored as novel nanomaterials... for catalysis, semiconductors, and even anti-cancer treatment due to their unique chemical, optical and electrical characteristics. We have explored the blending of inorganic POM nanocluster with BCPs into hierarchaically structured inorganic-organic hybrid nanocomposites. Using polystyrene-b-poly(ethylene oxide) (PS-b-PEO) thin films as the template, we have observed that the spatial organization of BCP thin films is modified by molybdenum based POM nanocluster to form 2D in-plane hexagonal ordered or 3D ordered network of POM-BCP assemblies, depending on the concentration ratio of POM to PS-b-PEO. The dielectric properties of such hybrid thin films can be enhanced by embedded POMs but show a strong dependence on the supramolecular structures of POM-polymer complexes. The assembly of nanoclusters in BCP-templated thin films could pave a new path to design new hybrid nanocomposites with uniquely combined functionality and material properties.

  7. Organic Thin-Film Transistor (OTFT-Based Sensors

    Directory of Open Access Journals (Sweden)

    Daniel Elkington

    2014-04-01

    Full Text Available Organic thin film transistors have been a popular research topic in recent decades and have found applications from flexible displays to disposable sensors. In this review, we present an overview of some notable articles reporting sensing applications for organic transistors with a focus on the most recent publications. In particular, we concentrate on three main types of organic transistor-based sensors: biosensors, pressure sensors and “e-nose”/vapour sensors.

  8. Organic Thin-Film Transistor (OTFT)-Based Sensors

    OpenAIRE

    Daniel Elkington; Nathan Cooling; Warwick Belcher; Paul C. Dastoor; Xiaojing Zhou

    2014-01-01

    Organic thin film transistors have been a popular research topic in recent decades and have found applications from flexible displays to disposable sensors. In this review, we present an overview of some notable articles reporting sensing applications for organic transistors with a focus on the most recent publications. In particular, we concentrate on three main types of organic transistor-based sensors: biosensors, pressure sensors and “e-nose”/vapour sensors.

  9. MEMS-based thin-film fuel cells

    Science.gov (United States)

    Jankowksi, Alan F.; Morse, Jeffrey D.

    2003-10-28

    A micro-electro-mechanical systems (MEMS) based thin-film fuel cells for electrical power applications. The MEMS-based fuel cell may be of a solid oxide type (SOFC), a solid polymer type (SPFC), or a proton exchange membrane type (PEMFC), and each fuel cell basically consists of an anode and a cathode separated by an electrolyte layer. Additionally catalyst layers can also separate the electrodes (cathode and anode) from the electrolyte. Gas manifolds are utilized to transport the fuel and oxidant to each cell and provide a path for exhaust gases. The electrical current generated from each cell is drawn away with an interconnect and support structure integrated with the gas manifold. The fuel cells utilize integrated resistive heaters for efficient heating of the materials. By combining MEMS technology with thin-film deposition technology, thin-film fuel cells having microflow channels and full-integrated circuitry can be produced that will lower the operating temperature an will yield an order of magnitude greater power density than the currently known fuel cells.

  10. Tantalum-based thin film coatings for wear resistant arthroprostheses.

    Science.gov (United States)

    Balagna, C; Faga, M G; Spriano, S

    2011-10-01

    Cobalt-chromium-molybdenum alloys with high carbon content (HC-CoCrMo) are widely used as materials for arthroprosthesis, in particular in metal-on-metal (MoM) hip joints. In spite of their good wear and corrosion resistance, production of metallic wear particles and metal ion release will occur on a large time-scale. An enhancement of the metal ion level in the patient's blood and urine is often reported in clinical data. Hypersensitivity, inflammatory response and cell necrosis can occur as consequence. So implants on young patients and women on childbearing age are not so widespread. The aim of this research is the realization of a thin film coating in order to improve the biocompatibility of Co-based alloys and to reduce debris production, ion release and citotoxicity. The innovative process consists of a thermal treatment in molten salts, in order to obtain a tantalum enriched thin film coating. Tantalum is chosen because it is considered a biocompatible metal with high corrosion resistance and low ion release. Three HC-CoCrMo alloys, produced by different manufacturing processes, are tested as substrates. The coating is a thin film of TaC or it can be composed by a multilayer of two tantalum carbides and metallic tantalum, depending on the temperature of the treatment and on the carbon content of the substrate. The thin films as well the substrates are characterized from the structural, chemical and morphological point of view. Moreover mechanical behaviour of treated and untreated materials is analyzed by means of nanohardness, scratch and ball-on-disc wear tests. The coating increases the mechanical and tribological properties of HC-CoCrMo. PMID:22400292

  11. Electrochromic Devices Based on Porous Tungsten Oxide Thin Films

    Directory of Open Access Journals (Sweden)

    Y. Djaoued

    2012-01-01

    Full Text Available Recent developments in the synthesis of transition metal oxides in the form of porous thin films have opened up opportunities in the construction of electrochromic devices with enhanced properties. In this paper, synthesis, characterization and electrochromic applications of porous WO3 thin films with different nanocrystalline phases, such as hexagonal, monoclinic, and orthorhombic, are presented. Asymmetric electrochromic devices have been constructed based on these porous WO3 thin films. XRD measurements of the intercalation/deintercalation of Li+ into/from the WO3 layer of the device as a function of applied coloration/bleaching voltages show systematic changes in the lattice parameters associated with structural phase transitions in LixWO3. Micro-Raman studies show systematic crystalline phase changes in the spectra of WO3 layers during Li+ ion intercalation and deintercalation, which agree with the XRD data. These devices exhibit interesting optical modulation (up to ~70% due to intercalation/deintercalation of Li ions into/from the WO3 layer of the devices as a function of applied coloration/bleaching voltages. The obtained optical modulation of the electrochromic devices indicates that, they are suitable for applications in electrochromic smart windows.

  12. Copper zinc tin sulfide-based thin film solar cells

    CERN Document Server

    Ito, Kentaro

    2014-01-01

    Beginning with an overview and historical background of Copper Zinc Tin Sulphide (CZTS) technology, subsequent chapters cover properties of CZTS thin films, different preparation methods of CZTS thin films, a comparative study of CZTS and CIGS solar cell, computational approach, and future applications of CZTS thin film solar modules to both ground-mount and rooftop installation. The semiconducting compound (CZTS) is made up earth-abundant, low-cost and non-toxic elements, which make it an ideal candidate to replace Cu(In,Ga)Se2 (CIGS) and CdTe solar cells which face material scarcity and tox

  13. Optical switch based on nanocrystalline VOx thin film

    Science.gov (United States)

    Chen, Xiqu; Dai, Jun

    2009-11-01

    An optical switch is fabricated based on nanocrystalline vanadium oxide (VOx) thin film using micromachining technology. An "on" state with semiconducting phase to an "off" state with metallic phase is controlled by applying a DC power to Aurum electrodes of the optical switch. The optical switching performance for the fabricated device is investigated at optical communication wavelength of 1.55μm. The heater power requires to achieve switching action is about 15mW. The testing results show that the extinction ratio and switching response time are 14dB and 2ms, respectively.

  14. Large area radiation detectors based on II VI thin films

    Science.gov (United States)

    Quevedo-Lopez, Manuel

    2015-03-01

    The development of low temperature device technologies that have enabled flexible displays also present opportunities for flexible electronics and flexible integrated systems. Of particular interest are possible applications in flexible, low metal content, sensor systems for unattended ground sensors, smart medical bandages, electronic ID tags for geo-location, conformal antennas, neutron/gamma-ray/x-ray detectors, etc. In this talk, our efforts to develop novel CMOS integration schemes, circuits, memory, sensors as well as novel contacts, dielectrics and semiconductors for flexible electronics are presented. In particular, in this presentation we discuss fundamental materials properties including crystalline structure, interfacial reactions, doping, etc. defining performance and reliability of II-VI-based radiation sensors. We investigate the optimal thickness of a semiconductor diode for thin-film solid state thermal neutron detectors. Besides II-VI materials, we also evaluated several diode materials, Si, CdTe,GaAs, C (diamond), and ZnO, and two neutron converter materials,10B and 6LiF. We determine the minimum semiconductor thickness needed to achieve maximum neutron detection efficiency. By keeping the semiconductor thickness to a minimum, gamma rejection is kept as high as possible. In this way, we optimize detector performance for different thin-film semiconductor materials.

  15. Thin Films

    Directory of Open Access Journals (Sweden)

    M. Benmouss

    2003-01-01

    the optical absorption are consistent with the film color changes. Finally, the optical and electrochromic properties of the films prepared by this method are compared with those of our sputtered films already studied and with other works.

  16. Printed organic thin-film transistor-based integrated circuits

    International Nuclear Information System (INIS)

    Organic electronics is moving ahead on its journey towards reality. However, this technology will only be possible when it is able to meet specific criteria including flexibility, transparency, disposability and low cost. Printing is one of the conventional techniques to deposit thin films from solution-based ink. It is used worldwide for visual modes of information, and it is now poised to enter into the manufacturing processes of various consumer electronics. The continuous progress made in the field of functional organic semiconductors has achieved high solubility in common solvents as well as high charge carrier mobility, which offers ample opportunity for organic-based printed integrated circuits. In this paper, we present a comprehensive review of all-printed organic thin-film transistor-based integrated circuits, mainly ring oscillators. First, the necessity of all-printed organic integrated circuits is discussed; we consider how the gap between printed electronics and real applications can be bridged. Next, various materials for printed organic integrated circuits are discussed. The features of these circuits and their suitability for electronics using different printing and coating techniques follow. Interconnection technology is equally important to make this product industrially viable; much attention in this review is placed here. For high-frequency operation, channel length should be sufficiently small; this could be achievable with a combination of surface treatment-assisted printing or laser writing. Registration is also an important issue related to printing; the printed gate should be perfectly aligned with the source and drain to minimize parasitic capacitances. All-printed organic inverters and ring oscillators are discussed here, along with their importance. Finally, future applications of all-printed organic integrated circuits are highlighted. (paper)

  17. Lanthanide oxides thin films for graphene-based devices

    International Nuclear Information System (INIS)

    We study the application potential of gadolinium and dysprosium oxide for graphene-based devices. Lanthanide oxide thin films of defined thickness are deposited in the presence of oxygen as well as nitrogen at 400 C by thermal CVD on an n+-Si(100) substrate. The roughness of the films is determined by atomic force micrographs and the thickness by cross-section scanning electron microscopy. A breakdown field in the range of 0.3 Vnm-1 is determined by I-V measurements for both rare earth oxides. From C-V measurements at 1 MHz the dielectric constant of Gd2O3 (εr=9) and Dy2O3 (εr=8) are extracted. Since the dielectric constant of the rare earth oxides are higher compared to SiO2 we expect an improved screening of charged impurities and therefore an improved performance for graphene-based devices due to the oxides. By using a Fresnel-law based model the contrast of graphene is calculated as a function of wavelength for different oxide thicknesses and compared to optical and atomic force micrographs of exfoliated graphene on Gd2O3 and Dy2O3.

  18. Impedance effect of manganite thin film-based photodetectors

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    We report on the photodetector structures based on perovskite manganite La0.67Ca0.33MnO3 thin films on tilted SrTiO3 (001) substrates. The photovoltaic effect has been observed in response to excitation by 308 nm ultraviolet laser pulse irradiation in duration of 20 ns at room temperature. The outputs obtained required no amplification. To reduce the deformation of the signal detected, a series of testing measurements were made to investigate the impedance effect. When the impedance at the oscilloscope end matched to the co-axis cable, the signal trace was almost triangular and symmetrical, with response time equal to the excitation laser. In addation, the response linearly depends on the irradiated area for low on-sample energy. The devices work well under unbiased conditions and so are simple to configure for practical applications.

  19. Carbon nanotube thin film transistors based on aerosol methods

    International Nuclear Information System (INIS)

    We demonstrate a fabrication method for high-performance field-effect transistors (FETs) based on dry-processed random single-walled carbon nanotube networks (CNTNs) deposited at room temperature. This method is an advantageous alternative to solution-processed and direct CVD grown CNTN FETs, which allows using various substrate materials, including heat-intolerant plastic substrates, and enables an efficient, density-controlled, scalable deposition of as-produced single-walled CNTNs on the substrate directly from the aerosol (floating catalyst) synthesis reactor. Two types of thin film transistor (TFT) structures were fabricated to evaluate the FET performance of dry-processed CNTNs: bottom-gate transistors on Si/SiO2 substrates and top-gate transistors on polymer substrates. Devices exhibited on/off ratios up to 105 and field-effect mobilities up to 4 cm2 V-1 s-1. The suppression of hysteresis in the bottom-gate device transfer characteristics by means of thermal treatment in vacuum and passivation by an atomic layer deposited Al2O3 film was investigated. A 32 nm thick Al2O3 layer was found to be able to eliminate the hysteresis.

  20. Handbook of thin film technology

    CERN Document Server

    Frey, Hartmut

    2015-01-01

    “Handbook of Thin Film Technology” covers all aspects of coatings preparation, characterization and applications. Different deposition techniques based on vacuum and plasma processes are presented. Methods of surface and thin film analysis including coating thickness, structural, optical, electrical, mechanical and magnetic properties of films are detailed described. The several applications of thin coatings and a special chapter focusing on nanoparticle-based films can be found in this handbook. A complete reference for students and professionals interested in the science and technology of thin films.

  1. Bismuth pyrochlore-based thin films for dielectric energy storage

    Science.gov (United States)

    Michael, Elizabeth K.

    The drive towards the miniaturization of electronic devices has created a need for dielectric materials with large energy storage densities. These materials, which are used in capacitors, are a critical component in many electrical systems. Here, the development of dielectric energy storage materials for pulsed power applications, which require materials with the ability to accumulate a large amount of energy and then deliver it to the system rapidly, is explored. The amount of electrostatic energy that can be stored by a material is a function of the induced polarization and the dielectric breakdown strength of the material. An ideal energy storage dielectric would possess a high relative permittivity, high dielectric breakdown strength, and low loss tangent under high applied electric fields. The bismuth pyrochlores are a compositionally tunable family of materials that meet these requirements. Thin films of cubic pyrochlore bismuth zinc niobate, bismuth zinc tantalate, and bismuth zinc niobate tantalate, were fabricated using a novel solution chemistry based upon the Pechini method. This solution preparation is advantageous because it avoids the use of teratogenic solvents, such as 2-methoxyethanol. Crystalline films fabricated using this solution chemistry had very small grains that were approximately 27 nm in lateral size and 35 nm through the film thickness. Impedance measurements found that the resistivity of the grain boundaries was two orders of magnitude higher than the resistivity of the grain interior. The presence of many resistive grain boundaries impeded conduction through the films, resulting in high breakdown strengths for these materials. In addition to high breakdown strengths, this family of materials exhibited moderate relative permittivities of between 55 +/- 2 and 145 +/- 5, for bismuth zinc tantalate and bismuth zinc niobate, respectively, and low loss tangents on the order of 0.0008 +/- 0.0001. Increases in the concentration of the tantalum

  2. Thin-film chemical sensors based on electron tunneling

    Science.gov (United States)

    Khanna, S. K.; Lambe, J.; Leduc, H. G.; Thakoor, A. P.

    1985-01-01

    The physical mechanisms underlying a novel chemical sensor based on electron tunneling in metal-insulator-metal (MIM) tunnel junctions were studied. Chemical sensors based on electron tunneling were shown to be sensitive to a variety of substances that include iodine, mercury, bismuth, ethylenedibromide, and ethylenedichloride. A sensitivity of 13 parts per billion of iodine dissolved in hexane was demonstrated. The physical mechanisms involved in the chemical sensitivity of these devices were determined to be the chemical alteration of the surface electronic structure of the top metal electrode in the MIM structure. In addition, electroreflectance spectroscopy (ERS) was studied as a complementary surface-sensitive technique. ERS was shown to be sensitive to both iodine and mercury. Electrolyte electroreflectance and solid-state MIM electroreflectance revealed qualitatively the same chemical response. A modified thin-film structure was also studied in which a chemically active layer was introduced at the top Metal-Insulator interface of the MIM devices. Cobalt phthalocyanine was used for the chemically active layer in this study. Devices modified in this way were shown to be sensitive to iodine and nitrogen dioxide. The chemical sensitivity of the modified structure was due to conductance changes in the active layer.

  3. Design of camouflage material for visible and near infrared based on thin film technology

    Science.gov (United States)

    Miao, Lei; Shi, Jia-ming; Zhao, Da-peng; Liu, Hao; Wang, Chao; Xu, Yan-liang

    2015-11-01

    Visible light and near infrared based camouflage materials achieve good stealth under traditional optical detection equipment but its spectral differences with green plants can be taken advantage of by high spectrum based detection technologies. Based on the thin structure of bandpass filter, we designed an optical film with both green and near infrared spectrum. We conducted simulations using transfer matrix methods and optimized the result by simplex methods. The spectral reflectance curve of the proposed thin film matches that of green plants, and experiments show that the proposed thin film achieve good invisibility under visible light and near infrared in a wide viewing angle.

  4. Thin film processes II

    CERN Document Server

    Kern, Werner

    1991-01-01

    This sequel to the 1978 classic, Thin Film Processes, gives a clear, practical exposition of important thin film deposition and etching processes that have not yet been adequately reviewed. It discusses selected processes in tutorial overviews with implementation guide lines and an introduction to the literature. Though edited to stand alone, when taken together, Thin Film Processes II and its predecessor present a thorough grounding in modern thin film techniques.Key Features* Provides an all-new sequel to the 1978 classic, Thin Film Processes* Introduces new topics, and sever

  5. Pyrolyzed thin film carbon

    Science.gov (United States)

    Tai, Yu-Chong (Inventor); Liger, Matthieu (Inventor); Harder, Theodore (Inventor); Konishi, Satoshi (Inventor); Miserendino, Scott (Inventor)

    2010-01-01

    A method of making carbon thin films comprises depositing a catalyst on a substrate, depositing a hydrocarbon in contact with the catalyst and pyrolyzing the hydrocarbon. A method of controlling a carbon thin film density comprises etching a cavity into a substrate, depositing a hydrocarbon into the cavity, and pyrolyzing the hydrocarbon while in the cavity to form a carbon thin film. Controlling a carbon thin film density is achieved by changing the volume of the cavity. Methods of making carbon containing patterned structures are also provided. Carbon thin films and carbon containing patterned structures can be used in NEMS, MEMS, liquid chromatography, and sensor devices.

  6. Thin film lithium-based batteries and electrochromic devices fabricated with nanocomposite electrode materials

    Science.gov (United States)

    Gillaspie, Dane T; Lee, Se-Hee; Tracy, C. Edwin; Pitts, John Roland

    2014-02-04

    Thin-film lithium-based batteries and electrochromic devices (10) are fabricated with positive electrodes (12) comprising a nanocomposite material composed of lithiated metal oxide nanoparticles (40) dispersed in a matrix composed of lithium tungsten oxide.

  7. Thin Film Microbatteries

    International Nuclear Information System (INIS)

    Thin film batteries are built layer by layer by vapor deposition. The resulting battery is formed of parallel plates, much as an ordinary battery construction, just much thinner. The figure (Fig. 1) shows an example of a thin film battery layout where films are deposited symmetrically onto both sides of a supporting substrate. The full stack of films is only 10 to 15 (micro)m thick, but including the support at least doubles the overall battery thickness. When the support is thin, the entire battery can be flexible. At least six companies have commercialized or are very close to commercializing such all-solid-state thin film batteries and market research predicts a growing market and a variety of applications including sensors, RFID tags, and smarter cards. In principle with a large deposition system, a thin film battery might cover a square meter, but in practice, most development is targeting individual cells with active areas less than 25 cm2. For very small battery areas, 2, microfabrication processes have been developed. Typically the assembled batteries have capacities from 0.1 to 5 mAh. The operation of a thin film battery is depicted in the schematic diagram (Fig. 2). Very simply, when the battery is allowed to discharge, a Li+ ion migrates from the anode to the cathode film by diffusing through the solid electrolyte. When the anode and cathode reactions are reversible, as for an intercalation compound or alloy, the battery can be recharged by reversing the current. The difference in the electrochemical potential of the lithium determines the cell voltage. Most of the thin films used in current commercial variations of this thin film battery are deposited in vacuum chambers by RF and DC magnetron sputtering and by thermal evaporation onto unheated substrates. In addition, many publications report exploring a variety of other physical and chemical vapor deposition processes, such as pulsed laser deposition, electron cyclotron resonance sputtering, and

  8. Thermal conductivity and mechanical properties of AlN-based thin films

    Science.gov (United States)

    Moraes, V.; Riedl, H.; Rachbauer, R.; Kolozsvári, S.; Ikeda, M.; Prochaska, L.; Paschen, S.; Mayrhofer, P. H.

    2016-06-01

    While many research activities concentrate on mechanical properties and thermal stabilities of protective thin films, only little is known about their thermal properties being essential for the thermal management in various industrial applications. Based on the 3ω-method, we show the influence of Al and Cr on the temperature dependent thermal conductivity of single-phase cubic structured TiN and single-phase wurtzite structured AlN thin films, respectively, and compare them with the results obtained for CrN thin films. The dc sputtered AlN thin films revealed a highly c-axis oriented growth for deposition temperatures of 250 to 700 °C. Their thermal conductivity was found to increase strongly with the film thickness, indicating progressing crystallization of the interface near amorphous regions during the sputtering process. For the 940 nm AlN film, we found a lower boundary for the thermal conductivity of 55.3 W m-1 K-1 . By the substitution of only 10 at. % Al with Cr, κ significantly reduces to ˜5.0 W m-1 K-1 , although the single-phase wurtzite structure is maintained. The single-phase face centered cubic TiN and Ti0.36Al0.64N thin films exhibit κ values of 3.1 W m-1 K-1 and 2.5 W m-1 K-1 , respectively, at room temperature. Hence, also here, the substitutional alloying reduces the thermal conductivity, although at a significantly lower level. Single-phase face centered cubic CrN thin films show κ values of 3.6 W m-1 K-1 . For all nitride based thin films investigated, the thermal conductivity slightly increases with increasing temperature between 200 and 330 K. This rather unusual behavior is based on the high defect density (especially point defects) within the thin films prepared by physical vapor deposition.

  9. Thin Film Absorbers Based on Plasmonic Phase Resonances

    CERN Document Server

    Cui, Yanxia; Xu, Jun; He, Sailing; Fang, Nicholas X

    2010-01-01

    We demonstrate an efficient double-layer light absorber by exciting plasmonic phase resonances. We show that the addition of grooves can cause mode splitting of the plasmonic waveguide cavity modes and all the new resonant modes exhibit large absorptivity greater than 90%. Some of the generated absorption peaks have wide-angle characteristics. Furthermore, we find that the proposed structure is fairly insensitive to the alignment error between different layers. The proposed plasmonic nano-structure designs may have exciting potential applications in thin film solar cells, thermal emitters, novel infrared detectors, and highly sensitive bio-sensors.

  10. A Naphthalenediimide-Based Metal-Organic Framework and Thin Film Exhibiting Photochromic and Electrochromic Properties.

    Science.gov (United States)

    Xie, Yi-Xin; Zhao, Wen-Na; Li, Guo-Chang; Liu, Peng-Fei; Han, Lei

    2016-01-19

    A multifunctional metal-organic framework, NBU-3, has been explored as a 2D three-connected network based on a naphthalenediimide-based ligand. The NBU-3 crystals display photochromic properties, and NBU-3 thin films on FTO substrates exhibit electrochromic properties. NBU-3 is the first example of MOF materials containing both photochromic and electrochromic properties, which can be desirable for thin film devices. PMID:26713454

  11. ZnO-Based Transparent Conductive Thin Films: Doping, Performance, and Processing

    International Nuclear Information System (INIS)

    ZnO-based transparent conductive thin films have attracted much attention as a promising substitute material to the currently used indium-tin-oxide thin films in transparent electrode applications. However, the detailed function of the dopants, acting on the electrical and optical properties of ZnO-based transparent conductive thin films, is not clear yet, which has limited the development and practical applications of ZnO transparent conductive thin films. Growth conditions such as substrate type, growth temperature, and ambient atmosphere all play important roles in structural, electrical, and optical properties of films. This paper takes a panoramic view on properties of ZnO thin films and reviews the very recent works on new, efficient, low-temperature, and high-speed deposition technologies. In addition, we highlighted the methods of producing ZnO-based transparent conductive film on flexible substrate, one of the most promising and rapidly emerging research areas. As optimum-processing-parameter conditions are being obtained and their influencing mechanism is becoming clear, we can see that there will be a promising future for ZnO-based transparent conductive films.

  12. Photoluminescence-based quality control for thin film absorber layers of photovoltaic devices

    Energy Technology Data Exchange (ETDEWEB)

    Repins, Ingrid L.; Kuciauskas, Darius

    2015-07-07

    A time-resolved photoluminescence-based system providing quality control during manufacture of thin film absorber layers for photovoltaic devices. The system includes a laser generating excitation beams and an optical fiber with an end used both for directing each excitation beam onto a thin film absorber layer and for collecting photoluminescence from the absorber layer. The system includes a processor determining a quality control parameter such as minority carrier lifetime of the thin film absorber layer based on the collected photoluminescence. In some implementations, the laser is a low power, pulsed diode laser having photon energy at least great enough to excite electron hole pairs in the thin film absorber layer. The scattered light may be filterable from the collected photoluminescence, and the system may include a dichroic beam splitter and a filter that transmit the photoluminescence and remove scattered laser light prior to delivery to a photodetector and a digital oscilloscope.

  13. Nonlinear model-based control of thin-film drying for continuous pharmaceutical manufacturing

    OpenAIRE

    Mesbah, A.; Ford Versypt, AN; Zhu, X.; Braatz, RD

    2014-01-01

    This paper considers the model-based control of composition and thickness for a thin-film drying process used in the continuous manufacturing of pharmaceutical tablets. In this nonlinear distributed dynamical system, a drug formulation solution is coated onto a moving surface and then dried to form thin films of approximately 250 μm in thickness. A dynamic optimizer is designed that employs a first-principles process model to simulate the spatial distribution of solvent concentration in the f...

  14. Ferroelectric memory element based on thin film field effect transistor

    Science.gov (United States)

    Poghosyan, A. R.; Aghamalyan, N. R.; Elbakyan, E. Y.; Guo, R.; Hovsepyan, R. K.

    2013-09-01

    We report the preparation and investigation of ferroelectric field effect transistors (FET) using ZnO:Li films with high field mobility of the charge carriers as a FET channel and as a ferroelectric active element simultaneously. The possibility for using of ferroelectric FET based on the ZnO:Li films in the ZnO:Li/LaB6 heterostructure as a bi-stable memory element for information recording is shown. The proposed ferroelectric memory structure does not manifest a fatigue after multiple readout of once recorded information.

  15. Amorphous IZO-based transparent thin film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Paine, David C. [Division of Engineering, Brown University, Providence, RI 02912 (United States)], E-mail: David_Paine@Brown.edu; Yaglioglu, Burag; Beiley, Zach; Lee, Sunghwan [Division of Engineering, Brown University, Providence, RI 02912 (United States)

    2008-07-01

    Active electronics implemented on cheap flexible polymer substrates offer the promise of novel display technologies, wearable electronics, large area memory, and a multitude of other, as-yet-unthought-of applications that require low cost and high volume manufacturing. Thin film transistors (TFT's) fabricated on temperature-sensitive plastic substrates at low temperatures are the key to this technology. TFT's that use metal (In, Zn, Sn, Ga) oxide channels offer both high mobility (relative to amorphous Si) and the advantage of optical transparency in the visible regime. We report on the fabrication and performance of amorphous oxide transparent thin film transistors that use dc-magnetron sputter techniques to deposit IZO (In{sub 2}O{sub 3} - 10 wt.% ZnO) at low oxygen potential (0 vol.% O{sub 2}) for the source, drain, and gate-contact metallization and, at higher oxygen partial pressures (10 vol.% O{sub 2}), for the semi-conducting channel. The devices in this study were processed at room temperature except for a single 280 {sup o}C PECVD deposition step to deposit a 230 nm-thick SiO{sub x} gate dielectric. The devices are optically transparent and operate in depletion mode with a threshold voltage of - 5 V, mobility of 15 cm{sup 2}/V s, an on-off ratio of > 10{sup 6} and, a sub-threshold slope of 1.2 V/decade. In addition, we report persistent photo-conductivity in the channel region of these devices when exposed to UV illumination.

  16. Ferroelectricity and antiferroelectricity of doped thin HfO2-based films.

    Science.gov (United States)

    Park, Min Hyuk; Lee, Young Hwan; Kim, Han Joon; Kim, Yu Jin; Moon, Taehwan; Kim, Keum Do; Müller, Johannes; Kersch, Alfred; Schroeder, Uwe; Mikolajick, Thomas; Hwang, Cheol Seong

    2015-03-18

    The recent progress in ferroelectricity and antiferroelectricity in HfO2-based thin films is reported. Most ferroelectric thin film research focuses on perovskite structure materials, such as Pb(Zr,Ti)O3, BaTiO3, and SrBi2Ta2O9, which are considered to be feasible candidate materials for non-volatile semiconductor memory devices. However, these conventional ferroelectrics suffer from various problems including poor Si-compatibility, environmental issues related to Pb, large physical thickness, low resistance to hydrogen, and small bandgap. In 2011, ferroelectricity in Si-doped HfO2 thin films was first reported. Various dopants, such as Si, Zr, Al, Y, Gd, Sr, and La can induce ferro-electricity or antiferroelectricity in thin HfO2 films. They have large remanent polarization of up to 45 μC cm(-2), and their coercive field (≈1-2 MV cm(-1)) is larger than conventional ferroelectric films by approximately one order of magnitude. Furthermore, they can be extremely thin (5 eV). These differences are believed to overcome the barriers of conventional ferroelectrics in memory applications, including ferroelectric field-effect-transistors and three-dimensional capacitors. Moreover, the coupling of electric and thermal properties of the antiferroelectric thin films is expected to be useful for various applications, including energy harvesting/storage, solid-state-cooling, and infrared sensors. PMID:25677113

  17. Optical characterization of antimony-based bismuth-doped thin films with different annealing temperatures

    Institute of Scientific and Technical Information of China (English)

    Xinmiao Lu; Yiqun Wu; Yang Wang; Jinsong Wei

    2011-01-01

    Antimony-b ased bismuth-doped thin film,a new kind of super-resolution mask layer,is prepared by magnetron sputtering.The structures and optical constants of the thin films before and after annealing are examined in detail.The as-deposited film is mainly in an amorphous state.After annealing at 170-370℃,it is converted to the rhombohedral-type of structure.The extent of crystallization increased with the annealing temperature.When the thin film is annealed,its refractive index decreased in the most visible region,whereas the extinction coefficient and reflectivity are markedly increased.The results indicate that the optical parameters of the film strongly depend on its microstructure and the bonding of the atoms.As demand for ultrahigh-density information storage continues to grow the recording mark size in optical memory is reduced to the nanometer scale [1- 4].Exceeding the optical diffraction limit with traditional optical storage technology has become a challenge[5-6].%Antimony-based bismuth-doped thin film, a new kind of super-resolution mask layer, is prepared by magnetron sputtering. The structures and optical constants of the thin films before and after annealing are examined in detail. The as-deposited film is mainly in an amorphous state. After annealing at 170-370℃, it is converted to the rhombohedral-type of structure. The extent of crystallization increased with the annealing temperature. When the thin film is annealed, its refractive index decreased in the most visible region, whereas the extinction coefficient and reflectivity are markedly increased. The results indicate that the optical parameters of the film strongly depend on its microstructure and the bonding of the atoms.

  18. Chiral atomically thin films

    Science.gov (United States)

    Kim, Cheol-Joo; Sánchez-Castillo, A.; Ziegler, Zack; Ogawa, Yui; Noguez, Cecilia; Park, Jiwoong

    2016-06-01

    Chiral materials possess left- and right-handed counterparts linked by mirror symmetry. These materials are useful for advanced applications in polarization optics, stereochemistry and spintronics. In particular, the realization of spatially uniform chiral films with atomic-scale control of their handedness could provide a powerful means for developing nanodevices with novel chiral properties. However, previous approaches based on natural or grown films, or arrays of fabricated building blocks, could not offer a direct means to program intrinsic chiral properties of the film on the atomic scale. Here, we report a chiral stacking approach, where two-dimensional materials are positioned layer-by-layer with precise control of the interlayer rotation (θ) and polarity, resulting in tunable chiral properties of the final stack. Using this method, we produce left- and right-handed bilayer graphene, that is, a two-atom-thick chiral film. The film displays one of the highest intrinsic ellipticity values (6.5 deg μm-1) ever reported, and a remarkably strong circular dichroism (CD) with the peak energy and sign tuned by θ and polarity. We show that these chiral properties originate from the large in-plane magnetic moment associated with the interlayer optical transition. Furthermore, we show that we can program the chiral properties of atomically thin films layer-by-layer by producing three-layer graphene films with structurally controlled CD spectra.

  19. Ceramic Composite Thin Films

    Science.gov (United States)

    Ruoff, Rodney S. (Inventor); Stankovich, Sasha (Inventor); Dikin, Dmitriy A. (Inventor); Nguyen, SonBinh T. (Inventor)

    2013-01-01

    A ceramic composite thin film or layer includes individual graphene oxide and/or electrically conductive graphene sheets dispersed in a ceramic (e.g. silica) matrix. The thin film or layer can be electrically conductive film or layer depending the amount of graphene sheets present. The composite films or layers are transparent, chemically inert and compatible with both glass and hydrophilic SiOx/silicon substrates. The composite film or layer can be produced by making a suspension of graphene oxide sheet fragments, introducing a silica-precursor or silica to the suspension to form a sol, depositing the sol on a substrate as thin film or layer, at least partially reducing the graphene oxide sheets to conductive graphene sheets, and thermally consolidating the thin film or layer to form a silica matrix in which the graphene oxide and/or graphene sheets are dispersed.

  20. Nucleophilic stabilization of water-based reactive ink for titania-based thin film inkjet printing

    DEFF Research Database (Denmark)

    Gadea, Christophe; Marani, Debora; Esposito, Vincenzo

    2017-01-01

    Drop on demand deposition (DoD) of titanium oxide thin films (<500 nm) is performed via a novel titanium-alkoxide-based solution that is tailored as a reactive ink for inkjet printing. The ink is developed as water-based solution by a combined use of titanium isopropoxide and n-methyldiethanolami......Drop on demand deposition (DoD) of titanium oxide thin films (reactive ink for inkjet printing. The ink is developed as water-based solution by a combined use of titanium isopropoxide and n......-methyldiethanolamine (MDEA) used as nucleophilic ligand. The function of the ligand is to control the fast hydrolysis/condensation reactions in water for the metal alkoxide before deposition, leading to formation of the TiO2 only after the jet process. The evolution of the titanium-ligand interactions at increasing amount...... of MDEA is here elucidated in terms of long term stability. The ink printability parameter (Z) is optimized, resulting in a reactive solution with printability, Z, >1, and chemical stability up to 600 h. Thin titanium oxide films (

  1. Optical fiber hydrogen sensor based on light reflection and a palladium-sliver thin film

    Institute of Scientific and Technical Information of China (English)

    CUI Lu-jun; SHANG Hui-chao; ZHANG Gang; ZHAO Ze-xiang; ZHOU Jun

    2011-01-01

    Thin alloy films of palladium (Pd) and silver (Ag) are deposited onto glass substrates via the direct current (DC) magnetron technique. The hydrogen sensor probe consists of optical fiber bundle and Pd/Ag optical thin film. When the sensor is exposed to hydrogen, the refractive index of Pd/Ag optical thin layer will diminish and cause attenuation changes of the reflective light. It is observed that the thickness of Pd/Ag alloy layer can affect the hydrogen sensor signal. Under different substrate temperatures, several Pd/Ag samples are coated with different thicknesses of Pd/Ag alloy, and the results of a hydrogen sensor based on reflective light from the Pd/Ag alloy thin film are discussed.

  2. Thin films on cantilevers

    NARCIS (Netherlands)

    Nazeer, Hammad

    2012-01-01

    The main goal of the work compiled in this thesis is to investigate thin films for integration in micro electromechanical systems (MEMS). The miniaturization of MEMS actuators and sensors without compromising their performance requires thin films of different active materials with specific propertie

  3. Thermal recrystallization of physical vapor deposition based germanium thin films on bulk silicon (100)

    KAUST Repository

    Hussain, Aftab M.

    2013-08-16

    We demonstrate a simple, low-cost, and scalable process for obtaining uniform, smooth surfaced, high quality mono-crystalline germanium (100) thin films on silicon (100). The germanium thin films were deposited on a silicon substrate using plasma-assisted sputtering based physical vapor deposition. They were crystallized by annealing at various temperatures ranging from 700 °C to 1100 °C. We report that the best quality germanium thin films are obtained above the melting point of germanium (937 °C), thus offering a method for in-situ Czochralski process. We show well-behaved high-κ /metal gate metal-oxide-semiconductor capacitors (MOSCAPs) using this film. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Tunable electrical conductivity in oriented thin films of tetrathiafulvalene-based covalent organic framework

    Energy Technology Data Exchange (ETDEWEB)

    Cai, SL; Zhang, YB; Pun, AB; He, B; Yang, JH; Toma, FM; Sharp, ID; Yaghi, OM; Fan, J; Zheng, SR; Zhang, WG; Liu, Y

    2014-09-16

    Despite the high charge-carrier mobility in covalent organic frameworks (COFs), the low intrinsic conductivity and poor solution processability still impose a great challenge for their applications in flexible electronics. We report the growth of oriented thin films of a tetrathiafulvalene-based COF (TTF-COF) and its tunable doping. The porous structure of the crystalline TTF-COF thin film allows the diffusion of dopants such as I-2 and tetracyanoquinodimethane (TCNQ) for redox reactions, while the closely packed 2D grid sheets facilitate the cross-layer delocalization of thus-formed TTF radical cations to generate more conductive mixed-valence TTF species, as is verified by UV-vis-NIR and electron paramagnetic resonance spectra. Conductivity as high as 0.28 S m(-1) is observed for the doped COF thin films, which is three orders of magnitude higher than that of the pristine film and is among the highest for COF materials.

  5. Optical band gap tuning of Sb-Se thin films for xerographic based applications

    Science.gov (United States)

    Kaur, Ramandeep; Singh, Palwinder; Singh, Kulwinder; Kumar, Akshay; Thakur, Anup

    2016-10-01

    In the present paper we have studied the effect of Sb addition on the optical band gap tuning of thermally evaporated SbxSe100-x (x = 0, 5, 20, 50 and 60) thin films. The structural investigations revealed that all thin films were amorphous in nature. Transmission spectrum was taken in the range 400-2500 nm shows that all films are highly transparent in the near infrared region. The fundamental absorption edge shifts towards longer wavelength with Sb incorporation. The optical band gap decreases with addition of antimony in a-Se thin films. A good correlation has been drawn between experimentally estimated and theoretically calculated optical band gap. The decrease in optical band gap of thin films has been explained using chemical bond approach and density of states model. Decrease in optical band gap with Sb addition increases the concentration of electron deep traps which increases the X-ray sensitivity of Sb-Se thin films. Thus by tuning the optical band gap of Sb-Se alloy, it could be utilized for xerographic based applications.

  6. Biocompatibility evaluation of sputtered zirconium-based thin film metallic glass-coated steels

    Directory of Open Access Journals (Sweden)

    Subramanian B

    2015-10-01

    Full Text Available Balasubramanian Subramanian,1 Sundaram Maruthamuthu,2 Senthilperumal Thanka Rajan1 1Electrochemical Material Science Division, 2Corrosion and Materials Protection Division, Central Electrochemical Research Institute, Karaikudi, India Abstract: Thin film metallic glasses comprised of Zr48Cu36Al8Ag8 (at.% of approximately 1.5 µm and 3 µm in thickness were prepared using magnetron sputtering onto medical grade 316L stainless steel. Their structural and mechanical properties, in vitro corrosion, and antimicrobial activity were analyzed. The amorphous thin film metallic glasses consisted of a single glassy phase, with an absence of any detectable peaks corresponding to crystalline phases. Elemental composition close to the target alloy was noted from EDAX analysis of the thin film. The surface morphology of the film showed a smooth surface on scanning electron microscopy and atomic force microscopy. In vitro electrochemical corrosion studies indicated that the zirconium-based metallic glass could withstand body fluid, showing superior resistance to corrosion and electrochemical stability. Interactions between the coated surface and bacteria were investigated by agar diffusion, solution suspension, and wet interfacial contact methods. The results indicated a clear zone of inhibition against the growth of microorganisms such as Escherichia coli and Staphylococcus aureus, confirming the antimicrobial activity of the thin film metallic glasses. Cytotoxicity studies using L929 fibroblast cells showed these coatings to be noncytotoxic in nature. Keywords: thin film metallic glasses, sputtering, biocompatibility, corrosion, antimicrobial activity

  7. Perpendicular Magnetic Anisotropy in Co-Based Full Heusler Alloy Thin Films

    Science.gov (United States)

    Wu, Y.; Xu, X. G.; Miao, J.; Jiang, Y.

    2015-12-01

    Half-metallic Co-based full Heusler alloys have been qualified as promising functional materials in spintronic devices due to their high spin polarization. The lack of perpendicular magnetic anisotropy (PMA) is one of the biggest obstacles restricting their application in next generation ultrahigh density storage such as magnetic random access memory (MARM). How to induce the PMA in Co-based full Heusler alloy thin films has attracted much research interest of scientists. This paper presents an overview of recent progress in this research area. We hope that this paper would provide some guidance and ideas to develop highly spin-polarized Co-based Heusler alloy thin films with PMA.

  8. Transparent conductive thin films based on polyaniline nanofibers

    International Nuclear Information System (INIS)

    Conducting polyaniline (PANI) nanofibers doped with sulphuric acid were synthesized by a sonochemical method and dispersed in methyl isobutyl ketone (MIBK) with ultrasonicating. The dispersion was mixed with poly(methyl methacrylate) (PMMA) solution in MIBK and cast to fabricate transparent conductive films with evaporation of the solvent. With only a mixing procedure and without any dispersant added, the PANI nanofibers were well dispersed in the matrix polymer as indicated by scanning electron microscopy (SEM) examination. The conductive composite films showed a percolation threshold at ca. 2.2 wt% owing to the relatively larger one-dimensional aspect ratios of the nanofibers. With loadings of PANI nanofibers in the range of 5-20 wt%, composite coatings in thickness of 1 μm with conductivities of 10-4 to 10-2 S/cm and transmittances higher than 40% in the visible spectrum can be achieved. The composite coatings showed good stability in air and solvents like water and isopropanol. Combined with their relatively easy preparing procedures, the PANI nanofibers based transparent conductive films can be great promise in practical applications

  9. Functionally graded alumina-based thin film systems

    Science.gov (United States)

    Moore, John J.; Zhong, Dalong

    2006-08-29

    The present invention provides coating systems that minimize thermal and residual stresses to create a fatigue- and soldering-resistant coating for aluminum die casting dies. The coating systems include at least three layers. The outer layer is an alumina- or boro-carbide-based outer layer that has superior non-wettability characteristics with molten aluminum coupled with oxidation and wear resistance. A functionally-graded intermediate layer or "interlayer" enhances the erosive wear, toughness, and corrosion resistance of the die. A thin adhesion layer of reactive metal is used between the die substrate and the interlayer to increase adhesion of the coating system to the die surface.

  10. PEALD YSZ-based bilayer electrolyte for thin film-solid oxide fuel cells

    Science.gov (United States)

    Yu, Wonjong; Cho, Gu Young; Hong, Soonwook; Lee, Yeageun; Kim, Young Beom; An, Jihwan; Cha, Suk Won

    2016-10-01

    Yttria-stabilized zirconia (YSZ) thin film electrolyte deposited by plasma enhanced atomic layer deposition (PEALD) was investigated. PEALD YSZ-based bi-layered thin film electrolyte was employed for thin film solid oxide fuel cells on nanoporous anodic aluminum oxide substrates, whose electrochemical performance was compared to the cell with sputtered YSZ-based electrolyte. The cell with PEALD YSZ electrolyte showed higher open circuit voltage (OCV) of 1.0 V and peak power density of 182 mW cm-2 at 450 °C compared to the one with sputtered YSZ electrolyte(0.88 V(OCV), 70 mW cm-2(peak power density)). High OCV and high power density of the cell with PEALD YSZ-based electrolyte is due to the reduction in ohmic and activation losses as well as the gas and electrical current tightness.

  11. Preparation routes based on magnetron sputtering for tungsten disulfide (WS2) films for thin-film solar cells

    International Nuclear Information System (INIS)

    The semiconductor tungsten disulfide (WS2) exhibits van der Waals bonding, crystallizes in a layer-type structure and is of interest as an absorber layer for thin-film solar cells. In this review article different preparation routes for WS2 thin films, based on magnetron sputtering, are reviewed. Films prepared by direct magnetron sputtering, though exhibiting quite a good structural quality, are not or only poorly photoactive. This can be attributed to the generation of recombination centers, especially sulfur vacancies, during the ion bombardment of the films, due to the low defect-formation energy of tungsten disulfide, an intrinsic property of transition metal dichalcogenides. A promising preparation route, which leads to photoactive WS2 films, is a two-step process, where, in a first step, a sulfur-rich, X-ray amorphous tungsten sulfide is deposited at low substrate temperatures onto a thin metal film (Ni, Co). This film sandwich is after wards annealed in an ampoule in a sulfur atmosphere or in flowing gas with a sufficient H2S partial pressure. From in-situ transmission electron microscopy and energy-dispersive X-ray diffraction, it was found that the WS2 film crystallization with a pronounced (001) texture is closely related to the formation of the liquid (eutectic) metal-sulfur phase. Based on these in-situ investigations the growth of the 2-dimensional WS2 nanosheets from an amorphous WS3+x precursor can be described as an amorphous solid-liquid-crystalline solid process (SLS), somewhat similar to the well-known vapor-liquid-solid (VLS) process for the growth of whiskers or nanorods and nanotubes. Research opportunities, to overcome current limitations for a broad use of WS2 (and MoS2) as thin-film solar cell absorbers are given. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. Development of Low-cost Chemical and Micromechanical Sensors Based on Thick-film,Thin-film and Electroplated Films

    Institute of Scientific and Technical Information of China (English)

    Wenmin Qu; Kurt Drescher

    2000-01-01

    Various films could be used as sensing materials or as constructional materials for the fabrication of chemical and micromechanical sensors. To illustrate this potential, three sensors fabricated by very different film deposition technologies are given as examples. The sensors are a humidity sensor in thickfilm technology, a multi-functional gas sensor in thin-film technology and a three-dimensional acceleration sensor chip manufactured by electroplating techniques. Design, fabrication and characterisation of these sensors are described in this paper.

  13. Thin films stress modeling : a novel approach

    OpenAIRE

    Bhattacharyya, A. S.; Ramgiri, Praveen Kumar

    2015-01-01

    A novel approach to estimate the thin film stress was discussed based on surface tension. The effect of temperature and film thickness was studies. The effect of stress on the film mechanical properties was observed.

  14. Biomimetic thin film synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Graff, G.L.; Campbell, A.A.; Gordon, N.R.

    1995-05-01

    The purpose of this program is to develop a new process for forming thin film coatings and to demonstrate that the biomimetic thin film technology developed at PNL is useful for industrial applications. In the biomimetic process, mineral deposition from aqueous solution is controlled by organic functional groups attached to the underlying substrate surface. The coatings process is simple, benign, inexpensive, energy efficient, and particularly suited for temperature sensitive substrate materials (such as polymers). In addition, biomimetic thin films can be deposited uniformly on complex shaped and porous substrates providing a unique capability over more traditional line-of-sight methods.

  15. Selective hydrogen gas sensor using CuFe2O4 nanoparticle based thin film

    Science.gov (United States)

    Haija, Mohammad Abu; Ayesh, Ahmad I.; Ahmed, Sadiqa; Katsiotis, Marios S.

    2016-04-01

    Hydrogen gas sensors based on CuFe2O4 nanoparticle thin films are presented in this work. Each gas sensor was prepared by depositing CuFe2O4 thin film on a glass substrate by dc sputtering inside a high vacuum chamber. Argon inert gas was used to sputter the material from a composite sputtering target. Interdigitated metal electrodes were deposited on top of the thin films by thermal evaporation and shadow masking. The produced sensors were tested against hydrogen, hydrogen sulfide, and ethylene gases where they were found to be selective for hydrogen. The sensitivity of the produced sensors was maximum for hydrogen gas at 50 °C. In addition, the produced sensors exhibit linear response signal for hydrogen gas with concentrations up to 5%. Those sensors have potential to be used for industrial applications because of their low power requirement, functionality at low temperatures, and low production cost.

  16. Optical Sensors Based on Single Arm Thin Film Waveguide Interferometer

    Science.gov (United States)

    Sarkisov, S. S.; Diggs, D.; Curley, M.; Adamovsky, Grigory (Technical Monitor)

    2001-01-01

    Single-arm double-mode double-order optical waveguide interferometer utilizes interference between two propagating modes of different orders. Sensing effect results from the change in propagation conditions of the modes caused by the environment. The waveguide is made as an open asymmetric slab structure containing a dye-doped polymer film onto a fused quartz substrate. It is more sensitive to the change of environment than its conventional polarimetric analog using orthogonal modes (TE and TM) of the same order. The sensor still preserves the option of operating in polarimetric regime using a variety of mode combinations such as TE(sub 0)/TM(sub 0) (conventional), TE(sub 0)/TM(sub 1), TE(sub 1)/TM(sub 0), or TE(sub 1)/TM(sub 1) but can also work in nonpolarimetric regime using combinations TE(sub 0)/TM(sub 1) or TE(sub 0)/TM(sub 1). Utilization of different mode combinations simultaneously makes the device more versatile. Application of the sensor to gas sensing is based on doping polymer film with an organic indicator dye sensitive to a particular gas. Change of optical absorption spectrum of the dye caused by the gaseous pollutant results change of the reactive index of the dye-doped polymer film that can be detected by the sensor. As an indicator dyes, we utilize Bromocresol Purple doped into polymer poly(methyl) methacrylate, which shows a reversible growth of the absorption peak neat 600 nm after exposure to wet ammonia. We have built a breadboard prototype of the sensor with He-Ne laser as a light source and with a single mode fiber input and a multimode fiber output. The prototype showed sensitivity to temperature change of the order of 2 C per one full oscillation of the signal. The sensitivity of the sensor to the presence of wet ammonia is 200 ppm per one full oscillation of the signal. The further improvements include switching to a longer wavelength laser source (750-nm semiconductor laser), substitution of poly(methyl) methacrylate with hydrophilic

  17. Transparent indium zinc oxide thin films used in photovoltaic cells based on polymer blends

    Energy Technology Data Exchange (ETDEWEB)

    Besleaga, Cristina; Ion, L. [University of Bucharest, Faculty of Physics, 405 Atomistilor Street, PO Box MG-11, 077125, Magurele-Ilfov (Romania); Ghenescu, Veta [University of Bucharest, Faculty of Physics, 405 Atomistilor Street, PO Box MG-11, 077125, Magurele-Ilfov (Romania); Institute for Space Sciences, 409 Atomistilor Street, PO Box MG-23, 077125, Magurele-Ilfov (Romania); Socol, G. [National Institute for Lasers, Plasma and Radiation Physics, PO Box MG-36, 077125, Magurele-Ilfov (Romania); Radu, A. [University of Bucharest, Faculty of Physics, 405 Atomistilor Street, PO Box MG-11, 077125, Magurele-Ilfov (Romania); Arghir, Iulia; Florica, Camelia [University of Bucharest, Faculty of Physics, 405 Atomistilor Street, PO Box MG-11, 077125, Magurele-Ilfov (Romania); National Institute of Materials Physics, 105 bis Atomistilor, PO Box MG.7, 077125 Magurele-Ilfov (Romania); Antohe, S., E-mail: santohe@solid.fizica.unibuc.ro [University of Bucharest, Faculty of Physics, 405 Atomistilor Street, PO Box MG-11, 077125, Magurele-Ilfov (Romania)

    2012-09-01

    Indium zinc oxide (IZO) thin films were obtained using pulsed laser deposition. The samples were prepared by ablation of targets with In concentrations, In/(In + Zn), of 80 at.%, at low substrate temperatures under reactive atmosphere. IZO films were used as transparent electrodes in polymer-based - poly(3-hexylthiophene) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61 1:1 blend - photovoltaic cells. The action spectra measurements revealed that IZO-based photovoltaic structures have performances comparable with those using indium-tin-oxide as transparent electrode. - Highlights: Black-Right-Pointing-Pointer Indium zinc oxide films were grown by pulsed laser deposition at room temperature. Black-Right-Pointing-Pointer The films had large free carrier density and reasonably high mobility. Black-Right-Pointing-Pointer These films fit for transparent electrodes in polymer-based photovoltaic cells.

  18. Thin film device applications

    CERN Document Server

    Kaur, Inderjeet

    1983-01-01

    Two-dimensional materials created ab initio by the process of condensation of atoms, molecules, or ions, called thin films, have unique properties significantly different from the corresponding bulk materials as a result of their physical dimensions, geometry, nonequilibrium microstructure, and metallurgy. Further, these characteristic features of thin films can be drasti­ cally modified and tailored to obtain the desired and required physical characteristics. These features form the basis of development of a host of extraordinary active and passive thin film device applications in the last two decades. On the one extreme, these applications are in the submicron dimensions in such areas as very large scale integration (VLSI), Josephson junction quantum interference devices, magnetic bubbles, and integrated optics. On the other extreme, large-area thin films are being used as selective coatings for solar thermal conversion, solar cells for photovoltaic conver­ sion, and protection and passivating layers. Ind...

  19. Development of a fluorescence based flux sensor for thin film growth and nanoparticle deposition

    Science.gov (United States)

    De Roo, Bert; Vervaele, Mattias; Rajala, Markku; Miller, Toni; Guillon, Herve; Seo, Jin Won; Locquet, Jean-Pierre

    2016-07-01

    An optical flux sensor, based on the fluorescence properties of materials and nanoparticles, has been developed to control the deposition rate in thin film deposition systems. Using a simple diode laser and a photomultiplier tube with a light filter, we report the detection of gallium atoms and CdSe-ZnS quantum dots. This setup has a high sensitivity and reproducibility.

  20. Excimer-like electroluminescence from thin films of switchable supermolecular anthracene-based rotaxanes

    NARCIS (Netherlands)

    Giro, G.; Cocchi, M.; Fattori, V.; Gadret, G.; Ruani, G.; Murgia, M.; Cavallini, M.; Biscarini, F.; Zamboni, R.; Loontjens, T.; Thies, J.; Leigh, D.A.; Morales, A.F.

    2001-01-01

    Thin films of 10-[3,5-di(terbutyl)phenoxy]decyl-2-({2-[(9-anthrylcarbonyl)amino]acetyl}amino) acetate (ANTPEP), the thread of an anthracene-based rotaxane, have been processed by the spin coating technique in a polycarbonate (PC) matrix. A single layer organic light emitting diode (OLED) has been de

  1. Fabrication of semi-transparent superoleophobic thin film from fabrics and nanoparticle-based hierarchical structure

    Directory of Open Access Journals (Sweden)

    Nishizawa S.

    2013-08-01

    Full Text Available Superoleophobic thin films have many potential applications including fluid transfer, fluid power systems, stain resistant and antifouling materials, and microfluidics among others. Transparency is also desired with superhydrophobicity for their numerous applications; however transparency and oleophobicity are almost incompatible relationship with each other in the point of surface structure. Because oleophobicity required rougher structure at nano-micro scale than hydrophobicity, and these rough structure brings light scattering. So far, there is very few report of the compatible of transparency and superoleophobicity. In this report, we proposed the see-through type fabrics using the nanoparticle-based hierarchical structure thin film for improving both of oleophobicity and transparency. The vacant space between fibrils of fabrics has two important roles: the one is to through the light, another one is to introduce air layer to realize Cassie state of liquid droplet on thin film. To realize the low surface energy and nanoscale rough structure surface on fibrils, we used the spray method with perfluoroalkyl methacrylic copolymer (PMC, silica nano particles and volatile solvent. From the SEM image, the hierarchical structures of nanoparticle were formed uniformly on the fabrics. The transparency of thin film obtained was approximately 61% and the change of transparency between pre-coated fabrics and coated was 11%. From investigation of the surface wettability, the contact angles of oils (rapeseed oil and hexadecane and water droplet on the fabricated film were over 150 degree.

  2. Positron and positronium annihilation in silica-based thin films studied by a pulsed positron beam

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, R. E-mail: r-suzuki@aist.go.jp; Ohdaira, T.; Kobayashi, Y.; Ito, K.; Shioya, Y.; Ishimaru, T

    2003-11-01

    Positron and positronium annihilation in silica-based thin films has been investigated by means of measurement techniques with a monoenergetic pulsed positron beam. The age-momentum correlation study revealed that positron annihilation in thermally grown SiO{sub 2} is basically the same as that in bulk amorphous SiO{sub 2} while o-Ps in the PECVD grown SiCOH film predominantly annihilate with electrons of C and H at the microvoid surfaces. We also discuss time-dependent three-gamma annihilation in porous low-k films by two-dimensional positron annihilation lifetime spectroscopy.

  3. Nanoresonator Enabled Ultrafast All-optical Terahertz Switching Based on Vanadium Dioxide Thin Film

    Science.gov (United States)

    Kyoung, J. S.; Choi, S. B.; Kim, H. S.; Kim, B. J.; Ahn, Y. H.; Kim, H. T.; Kim, D. S.

    2011-12-01

    We demonstrate nanoresonator enabled ultrafast all-optical switching of terahertz transmission based on phase transition of vanadium dioxide (VO2) thin film. Nanoresonators, nm-width slot antenna patterns on the gold layer, are fabricated on the VO2 films. Without nanoresonators, THz wave shows negligible change through bare VO2 film even though optical pumping exists, while about 20 percents switching ratio is clearly seen with nanoresonator patterns on the VO2. The switching time is in a few hundreds femtosecond time scales.

  4. Tunneling Nanoelectromechanical Switches Based on Compressible Molecular Thin Films.

    Science.gov (United States)

    Niroui, Farnaz; Wang, Annie I; Sletten, Ellen M; Song, Yi; Kong, Jing; Yablonovitch, Eli; Swager, Timothy M; Lang, Jeffrey H; Bulović, Vladimir

    2015-08-25

    Abrupt switching behavior and near-zero leakage current of nanoelectromechanical (NEM) switches are advantageous properties through which NEMs can outperform conventional semiconductor electrical switches. To date, however, typical NEMs structures require high actuation voltages and can prematurely fail through permanent adhesion (defined as stiction) of device components. To overcome these challenges, in the present work we propose a NEM switch, termed a "squitch," which is designed to electromechanically modulate the tunneling current through a nanometer-scale gap defined by an organic molecular film sandwiched between two electrodes. When voltage is applied across the electrodes, the generated electrostatic force compresses the sandwiched molecular layer, thereby reducing the tunneling gap and causing an exponential increase in the current through the device. The presence of the molecular layer avoids direct contact of the electrodes during the switching process. Furthermore, as the layer is compressed, the increasing surface adhesion forces are balanced by the elastic restoring force of the deformed molecules which can promote zero net stiction and recoverable switching. Through numerical analysis, we demonstrate the potential of optimizing squitch design to enable large on-off ratios beyond 6 orders of magnitude with operation in the sub-1 V regime and with nanoseconds switching times. Our preliminary experimental results based on metal-molecule-graphene devices suggest the feasibility of the proposed tunneling switching mechanism. With optimization of device design and material engineering, squitches can give rise to a broad range of low-power electronic applications. PMID:26244821

  5. Thermally Sprayed Coatings as Interlayers for DLC-Based Thin Films

    Science.gov (United States)

    Bolelli, G.; Gualtieri, E.; Lusvarghi, L.; Pighetti Mantini, F.; Pitacco, F.; Valeri, S.; Volz, H.

    2009-06-01

    This article examines the usefulness of a thick thermally sprayed interlayer (plasma-sprayed Ni-50%Cr, plasma-sprayed Al2O3-13%TiO2, or high-velocity oxygen-fuel-sprayed WC-17%Co) for enhancing the wear resistance and the corrosion protectiveness of a diamond-like carbon (DLC)-based thin film deposited onto a carbon steel substrate. Scratch tests indicate that the Al2O3-13%TiO2 and WC-17%Co interlayers definitely increase the critical spallation load of the thin film, but the Al2O3-13%TiO2 interlayer itself undergoes brittle fracture under high-contact loads. Accordingly, during ball-on-disk tests at room temperature, no cracking and spallation occur in the DLC-based film deposited onto the WC-17%Co interlayer, whereas the one onto the Al2O3-13%TiO2 interlayer is rapidly removed because the interlayer itself is fractured. At 300 °C, by contrast, the DLC-based film on the Al2O3-13%TiO2 interlayer offers the best tribological performance, possibly thanks to the increased toughness of the ceramic interlayer at this temperature. Electrochemical polarization tests indicate that the thin film/WC-Co systems possess the lowest corrosion current density.

  6. Evaporated VOx Thin Films

    Science.gov (United States)

    Stapinski, Tomasz; Leja, E.

    1989-03-01

    VOx thin films on glass were obtained by thermal evaporation of V205, powder. The structural investigations were carried out with the use of X-ray diffractometer. The electrical properties of the film were examined by means of temperature measurements of resistivity for the samples heat-treated in various conditions. Optical transmission and reflection spectra of VOX films of various composition showed the influence of the heat treatment.

  7. High-energy-density sol-gel thin film based on neat 2-cyanoethyltrimethoxysilane.

    Science.gov (United States)

    Kim, Yunsang; Kathaperumal, Mohanalingam; Smith, O'Neil L; Pan, Ming-Jen; Cai, Ye; Sandhage, Kenneth H; Perry, Joseph W

    2013-03-13

    Hybrid organic-inorganic sol-gel dielectric thin films from a neat 2-cyanoethyltrimethoxysilane (CNETMS) precursor have been fabricated and their permittivity, dielectric strength, and energy density characterized. CNETMS sol-gel films possess compact, polar cyanoethyl groups and exhibit a relative permittivity of 20 at 1 kHz and breakdown strengths ranging from 650 V/μm to 250 V/μm for film thicknesses of 1.3 to 3.5 μm. Capacitors based on CNETMS films exhibit extractable energy densities of 7 J/cm(3) at 300 V/μm, as determined by charge-discharge and polarization-electric field measurements, as well as an energy extraction efficiency of ~91%. The large extractable energy resulting from the linear dielectric polarization behavior suggests that CNETMS films are promising sol-gel materials for pulsed power applications. PMID:23427818

  8. New routes for epitaxial thin films of Fe-based superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Thersleff, Thomas; Haindl, Silvia; Iida, Kazumasa; Kurth, Fritz; Engelmann, Jan; Kidszun, Martin; Trommler, Sascha; Haenisch, Jens; Kauffmann, Alexander; Reich, Elke; Huehne, Ruben; Pohl, Darius; Hartmann, Andreas; Rellinghaus, Bernd; Schultz, Ludwig; Holzapfel, Bernhard [Institute for Metallic Materials, IFW Dresden (Germany)

    2011-07-01

    With the recent discovery of the Fe-based superconductors, a major question raised is their suitability for applications. Many of the most interesting devices require the controlled production of thin films with clean interfaces. During the laboratory production of Fe-based superconductor thin films, a detailed analysis by TEM of the substrate/film interface revealed evidence for secondary phase formation. On the basis of the observation of the formation of an Fe layer at the substrate/film interface for Co-doped BaFe{sub 2}As{sub 2}, we designed a bonding scheme between Fe and the iron pnictide phase, resulting in a new thin film architecture we have termed the 'Fe/Ba-122' bilayer system. The first results from this system reveal greatly enhanced growth properties and critical current densities with regard to deposition on pure oxide substrates and may provide a key to understanding a more general growth mechanism in this system.

  9. Structure and physicochemical properties of thin film photosemiconductor cells based on porphine derivatives

    Science.gov (United States)

    Kazak, A. V.; Usol'tseva, N. V.; Smirnova, A. I.; Bodnarchuk, V. V.; Sul'yanov, S. N.; Yablonskii, S. V.

    2016-05-01

    Photosemiconductor thin films based on two organic porphine derivatives have been investigated. These compounds have different pendent groups; the film morphology, along with the specific fabrication technique, is determined to a great extent by these groups. The films have been fabricated by vacuum sputtering and using the Langmuir-Schaefer method. According to the atomic force microscopy (AFM) data, the Langmuir-Schaefer films are more homogeneous than the sputtered ones. It is shown that the sputtered films based on substituted porphine have a looser stacking than the initial analog. A spectroscopy study revealed a bathochromic shift of the Soret band in the Langmuir-Schaefer films-sputtered films series. This shift is explained by the increase in the concentration and size of molecular aggregates in sputtered films. It is shown that a polycrystalline C60 fullerene film deposited onto an amorphous substituted porphine layer improves the photoelectric characteristics of the latter. Both the time stability of the photodiode structure and its ampere‒watt sensitivity increase (by a factor of 10 in the transition regime). The steady-state current does not change. The effect of polarity reversal of the photovoltaic signal is observed in a planar C60‒substituted metalloporphine heterostructure, which is similar to the pyroelectric effect. The polarity reversal can be explained by the contribution of the trap charge and discharge current at the interface between the amorphous photosemiconductor and crystalline photosemiconductor to the resulting photoelectric current.

  10. Progress in Thin Film Solar Cells Based on Cu2ZnSnS4

    Directory of Open Access Journals (Sweden)

    Hongxia Wang

    2011-01-01

    Full Text Available The research in thin film solar cells has been dominated by light absorber materials based on CdTe and Cu(In,GaSe2 (CIGS in the last several decades. The concerns of environment impact of cadmium and the limited availability of indium in those materials have driven the research towards developing new substitute light absorbers made from earth abundant, environment benign materials. Cu2ZnSnS4 (CZTS semiconductor material has emerged as one of the most promising candidates for this aim and has attracted considerable interest recently. Significant progress in this relatively new research area has been achieved in the last three years. Over 130 papers on CZTS have been published since 2007, and the majority of them are on the preparation of CZTS thin films by different methods. This paper, will review the wide range of techniques that have been used to deposit CZTS semiconductor thin films. The performance of the thin film solar cells using the CZTS material will also be discussed.

  11. Ti doped ZnO thin film based UV photodetector: Fabrication and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Shewale, P.S.; Lee, N.K.; Lee, S.H.; Kang, K.Y. [Convergence of IT Devices Institute, Dong-Eui University, Busan 614-714 (Korea, Republic of); Yu, Y.S., E-mail: ysyu@deu.ac.kr [Convergence of IT Devices Institute, Dong-Eui University, Busan 614-714 (Korea, Republic of); Department of Radiological Science, Dong-Eui University, Busan 614-714 (Korea, Republic of)

    2015-03-05

    Highlights: • UV photoconductive undoped and Ti doped ZnO films were grown by spray pyrolysis. • Ti doping effects on physical and UV detection properties of films were studied. • Samples are polycrystalline with a hexagonal wurtzite crystal structure. • Ti doping increases the optical transmittance and band gap of ZnO film. • Ti doping improves the responsivity of ZnO film based MSM UV photodetector. - Abstract: This paper presents the synthesis of undoped and 2 wt.% titanium (Ti) doped zinc oxide (ZnO) thin films onto glass substrates by chemical spray pyrolysis technique. Both films are deposited at 375 °C substrate temperature. The influence of Ti doping on structural, morphological, optical and UV detection properties of ZnO film was studied. Both films revealed to be of polycrystalline nature with a hexagonal wurtzite structure; and the ZnO film crystallinity improved on Ti doping. Surface morphological observations agreed well with structural results. The Ti incorporation in ZnO thin films were confirmed by an energy dispersive X-ray spectroscopic analysis (EDX). The Ti doping increased the optical transmittance (∼96% at 550) and band gap (∼3.2927 eV) of ZnO thin film. Further, the metal–semiconductor–metal (MSM) planar ultraviolet photodetectors (UV PDs) were fabricated from deposition of tin (Sn) contacts onto undoped and Ti doped ZnO films using e-beam evaporation technique. To investigate UV photodetection properties, the MSM devices were subjected to current–voltage (I–V) characteristics measurements of forward and reverse bias in dark and UV light conditions. The photocurrent and responsivity were measured as a function of optical power density and applied voltage, respectively. The reproducibility of the UV detection performance of MSM devices was ensured by constantly switching UV light on and off at regular time intervals. The Ti doped ZnO film based UV PD demonstrates highest responsivity of about 0.051 A/W upon 2 mW/cm{sup 2

  12. Chemical sensing employingpH sensitive emeraldine base thin film for carbon dioxide detection

    Science.gov (United States)

    Irimia-Vladu, Mihai

    Respiration, or CO2 evolution, is a universal indicator for all the biological activities. Among many potential applications, the measurement of CO2 evolution has been found to be a rapid and nondestructive means for examining microbial contamination of food. The sensor developed in this work consists of a thin emeraldine base-polyaniline (EB-PAni) film. In the first half of the project the effect of carbon dioxide over the conductivity of a composite film of emeraldine base polyaniline and poly(vinyl alcohol) in N-methyl pyrrolidone (NMP) respectively was tested. Argon gas or mixture of argon and 5% CO2 were circulated through the glass cell containing the polymer film deposited on interdigitated electrode and exposed to specific humidity levels fixed by aqueous supersaturated salt solutions. In the second half of the project, a thin emeraldine base film in NMP was directly deposited on interdigitated electrode and the respective sensor inserted in water. Carbonic acid solutions of various pHs were generated by bubbling specific mixtures of carbon dioxide and argon. Conductivity measurements were performed by impedance spectroscopy throughout the project. The sensing mechanism is based on intermediate stages of the transformation of the emeraldine base polyaniline to a conductive salt type (ES-PAni). This EB-ES transformation is the consequence of the exposure of EB-PAni to a protonic acid and is accompanied by a change in the conductivity of the polymer film. Carbonic acid, unfortunately, is a very weak acid and is unable to induce a conductivity change, but the intermediate steps that predetermine this transformation are detected by impedance spectroscopy even when the overall conductivity of the film is unchanged. The composite thin film developed in the first part of the project showed poor sensing characteristics: limited dynamic range, drift, instability and slow time response. However, the sensor design employed in the second half of this work, coupled with

  13. Heterogeneity in Polymer Thin Films

    OpenAIRE

    Kanaya, Toshiji; Inoue, Rintaro; Nishida, Koji

    2011-01-01

    In the last two decades very extensive studies have been performed on polymer thin films to reveal very interesting but unusual properties. One of the most interesting findings is the decrease in glass transition temperature Tg with film thickness in polystyrene (PS) thin film supported on Si substrate. Another interesting finding is apparent negative thermal expansivity in glassy state for thin films below ∼25 nm. In order to understand the unusual properties of polymer thin films we have st...

  14. Thin films and nanomaterials

    International Nuclear Information System (INIS)

    The objective of this book is to disseminate the most recent research in Thin Films, Nanomaterials, Corrosion and Metallurgy presented at the International Conference on Advanced Materials (ICAM 2011) held in PSG College of Technology, Coimbatore, India during 12-16 December 2011. The book is a compilation of 113 chapters written by active researchers providing information and critical insights into the recent advancements that have taken place. Important new applications are possible today in the fields of microelectronics, opto-electronics, metallurgy and energy by the application of thin films on solid surfaces. Recent progress in high vacuum technology and new materials has a remarkable effect in thin film quality and cost. This has led to the development of new single or multi-layered thin film devices with diverse applications in a multitude of production areas, such as optics, thermal barrier coatings and wear protections, enhancing service life of tools and to protect materials against thermal and atmospheric influence. On the other hand, thin film process techniques and research are strongly related to the basic research activities in nano technology, an increasingly important field with countless opportunities for applications due to the emergence of new properties at the nanoscale level. Materials and structures that are designed and fabricated at the nano scale level, offer the potential to produce new devices and processes that may enhance efficiencies and reduce costs in many areas, as photovoltaic systems, hydrogen storage, fuel cells and solar thermal systems. In the book, the contributed papers are classified under two sections i) thin films and ii) nanomaterials. The thin film section includes single or multi layer conducting, insulating or semiconducting films synthesized by a wide variety of physical or chemical techniques and characterized or analyzed for different applications. The nanomaterials section deals with novel or exciting materials

  15. Thin film photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Zweibel, K; Ullal, H S

    1989-05-01

    Thin films are considered a potentially attractive technological approach to making cost-effective electricity by photovoltaics. Over the last twenty years, many have been investigated and some (cadmium telluride, copper indium diselenide, amorphous silicon) have become leading candidates for future large-scale commercialization. This paper surveys the past development of these key thin films and gives their status and future prospects. In all cases, significant progress toward cost-effective PV electricity has been made. If this progress continues, it appears that thin film PV could provide electricity that is competitive for summer daytime peaking power requirements by the middle of the 1990s; and electricity in a range that is competitive with fossil fuel costs (i.e., 6 cents/kilowatt-hour) should be available from PV around the turn of the century. 22 refs., 9 figs.

  16. Thin film temperature sensor

    Science.gov (United States)

    Grant, H. P.; Przybyszewski, J. S.

    1980-01-01

    Thin film surface temperature sensors were developed. The sensors were made of platinum-platinum/10 percent rhodium thermocouples with associated thin film-to-lead wire connections and sputtered on aluminum oxide coated simulated turbine blades for testing. Tests included exposure to vibration, low velocity hydrocarbon hot gas flow to 1250 K, and furnace calibrations. Thermal electromotive force was typically two percent below standard type S thermocouples. Mean time to failure was 42 hours at a hot gas flow temperature of 1250 K and an average of 15 cycles to room temperature. Failures were mainly due to separation of the platinum thin film from the aluminum oxide surface. Several techniques to improve the adhesion of the platinum are discussed.

  17. Copper Oxide Thin Films through Solution Based Methods for Electrical Energy Conversion and Storage

    Science.gov (United States)

    Zhu, Changqiong

    Copper oxides (Cu2O and CuO), composed of non-toxic and earth abundant elements, are promising materials for electrical energy generation and storage devices. Solution based techniques for creating thin films of these materials, such as electrodeposition, are important to understand and develop because of their potential for realizing substantial energy savings compared to traditional fabrication methods. Cuprous oxide (Cu2O), with its direct band gap, is a p-type semiconductor that is well suited for creating solution-processed photovoltaic devices (solar cells); several key advancements made toward this application are the primary focus of this thesis. Electrodeposition of single-phase, crystalline Cu2O thin films is demonstrated using previously unexplored, acidic lactate/Cu2+ solutions, which has provided additional understanding of the impacts of growth solution chemistry on film formation. The influence of pH on the resulting Cu2O thin film properties is revealed by using the same ligand (sodium lactate) at various solution pH values. Cu2O films grown from acidic lactate solutions can exhibit a distinctive flowerlike, dendritic morphology, in contrast to the faceted, dense films obtained using alkaline lactate solutions. Relative speciation distributions of the various metal complex ions present under different growth conditions are calculated using reported equilibrium association constants and experimentally supported by UV-Visible absorption spectroscopy. Dependence of thin film morphology on the lactate/Cu2+ molar ratio and applied potential is described. Cu2O/eutectic gallium-indium Schottky junction devices are formed and devices are tested under monochromatic green LED illumination. Further surface examination of the Cu2O films using X-ray photoelectron spectroscopy (XPS) reveals the fact that films grown from acidic lactate solution with a small lactate/Cu2+ molar ratio, which exhibit improved photovoltaic performance compared to films grown from

  18. Magnetic properties of FeNi-based thin film materials with different additives

    KAUST Repository

    Liang, C.

    2014-07-04

    This paper presents a study of FeNi-based thin film materials deposited with Mo, Al and B using a co-sputtering process. The existence of soft magnetic properties in combination with strong magneto-mechanical coupling makes these materials attractive for sensor applications. Our findings show that FeNi deposited with Mo or Al yields magnetically soft materials and that depositing with B further increases the softness. The out-of-plane magnetic anisotropy of FeNi thin films is reduced by depositing with Al and completely removed by depositing with B. The effect of depositing with Mo is dependent on the Mo concentration. The coercivity of FeNiMo and FeNiAl is reduced to less than a half of that of FeNi, and a value as low as 40 A/m is obtained for FeNiB. The surfaces of the obtained FeNiMo, FeNiAl and FeNiB thin films reveal very different morphologies. The surface of FeNiMo shows nano-cracks, while the FeNiAl films show large clusters and fewer nano-cracks. When FeNi is deposited with B, a very smooth morphology is obtained. The crystal structure of FeNiMo strongly depends on the depositant concentration and changes into an amorphous structure at a higher Mo level. FeNiAl thin films remain polycrystalline, even at a very high concentration of Al, and FeNiB films are amorphous, even at a very low concentration of B. 2014 by the authors.

  19. Magnetic Properties of FeNi-Based Thin Film Materials with Different Additives

    Directory of Open Access Journals (Sweden)

    Cai Liang

    2014-07-01

    Full Text Available This paper presents a study of FeNi-based thin film materials deposited with Mo, Al and B using a co-sputtering process. The existence of soft magnetic properties in combination with strong magneto-mechanical coupling makes these materials attractive for sensor applications. Our findings show that FeNi deposited with Mo or Al yields magnetically soft materials and that depositing with B further increases the softness. The out-of-plane magnetic anisotropy of FeNi thin films is reduced by depositing with Al and completely removed by depositing with B. The effect of depositing with Mo is dependent on the Mo concentration. The coercivity of FeNiMo and FeNiAl is reduced to less than a half of that of FeNi, and a value as low as 40 A/m is obtained for FeNiB. The surfaces of the obtained FeNiMo, FeNiAl and FeNiB thin films reveal very different morphologies. The surface of FeNiMo shows nano-cracks, while the FeNiAl films show large clusters and fewer nano-cracks. When FeNi is deposited with B, a very smooth morphology is obtained. The crystal structure of FeNiMo strongly depends on the depositant concentration and changes into an amorphous structure at a higher Mo level. FeNiAl thin films remain polycrystalline, even at a very high concentration of Al, and FeNiB films are amorphous, even at a very low concentration of B.

  20. Color-neutral switchable mirrors based on magnesium-titanium thin films

    Science.gov (United States)

    Bao, S.; Tajima, K.; Yamada, Y.; Okada, M.; Yoshimura, K.

    2007-06-01

    In an investigation of smart-window applications of switchable mirror thin films, Pd-capped magnesium-titanium thin films were prepared by dc magnetron sputtering. Their optical properties, switching durability and crystalline structures have been investigated. We show that Pd/Mg-Ti thin films with specific thicknesses are completely color-neutral in the transparent state and their optical switching properties are suitable for building and automobile window glass applications. The ternary hydrides of Mg(1-x)Tix thin films with Pd overlayers are identified by in situ X-ray diffraction measurements during a hydrogen gas loading of 4%. Pd/Mg(1-x)Tix thin film switchable mirrors show fast hydriding and dehydriding kinetics as compared to a Pd-capped pure Mg thin film due to the catalytic role of doped metallic Ti.

  1. Thin film superfluid optomechanics

    CERN Document Server

    Baker, Christopher G; McAuslan, David L; Sachkou, Yauhen; He, Xin; Bowen, Warwick P

    2016-01-01

    Excitations in superfluid helium represent attractive mechanical degrees of freedom for cavity optomechanics schemes. Here we numerically and analytically investigate the properties of optomechanical resonators formed by thin films of superfluid $^4$He covering micrometer-scale whispering gallery mode cavities. We predict that through proper optimization of the interaction between film and optical field, large optomechanical coupling rates $g_0>2\\pi \\times 100$ kHz and single photon cooperativities $C_0>10$ are achievable. Our analytical model reveals the unconventional behaviour of these thin films, such as thicker and heavier films exhibiting smaller effective mass and larger zero point motion. The optomechanical system outlined here provides access to unusual regimes such as $g_0>\\Omega_M$ and opens the prospect of laser cooling a liquid into its quantum ground state.

  2. Thin film ceramic thermocouples

    Science.gov (United States)

    Gregory, Otto (Inventor); Fralick, Gustave (Inventor); Wrbanek, John (Inventor); You, Tao (Inventor)

    2011-01-01

    A thin film ceramic thermocouple (10) having two ceramic thermocouple (12, 14) that are in contact with each other in at least on point to form a junction, and wherein each element was prepared in a different oxygen/nitrogen/argon plasma. Since each element is prepared under different plasma conditions, they have different electrical conductivity and different charge carrier concentration. The thin film thermocouple (10) can be transparent. A versatile ceramic sensor system having an RTD heat flux sensor can be combined with a thermocouple and a strain sensor to yield a multifunctional ceramic sensor array. The transparent ceramic temperature sensor that could ultimately be used for calibration of optical sensors.

  3. Superconducting detector of IR single-photons based on thin WSi films

    CERN Document Server

    Seleznev, V A; Vakhtomin, Yu B; Morozov, P V; Zolotov, P I; Vasilev, D D; Moiseev, K M; Malevannaya, E I; Smirnov, K V

    2016-01-01

    We have developed the deposition technology of WSi thin films 4 to 9 nm thick with high temperature values of superconducting transition (Tc~4 K). Based on deposed films there were produced nanostructures with indicative planar sizes ~100 nm, and the research revealed that even on nanoscale the films possess of high critical temperature values of the superconducting transition (Tc~3.3-3.7K ) which certifies high quality and homogeneity of the films created. The first experiments on creating superconducting single-photon detectors showed that the detectors SDE (system detection efficiency) with increasing bias current (Ib) reaches a constant value of ~30% (for 1550 nm) defined by infrared radiation absorption by the superconducting structure. To enhance radiation absorption by the superconductor there were created detectors with cavity structures which demonstrated a practically constant value of quantum efficiency >65% for bias currents Ib>=0.6Ic. The minimal dark counts level (DC) made 1 s^-1 limited with ba...

  4. PMMA–SiO{sub 2} hybrid films as gate dielectric for ZnO based thin-film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Morales-Acosta, M.D. [Centro de Investigación y de Estudios Avanzados del IPN, Unidad Querétaro, Apdo. Postal 1-798, Querétaro, Qro. 76001 (Mexico); Quevedo-López, M.A. [Department of Materials Science and Engineering, The University of Texas at Dallas, Richardson, TX 75083 (United States); Ramírez-Bon, R., E-mail: rrbon@qro.cinvestav.mx [Centro de Investigación y de Estudios Avanzados del IPN, Unidad Querétaro, Apdo. Postal 1-798, Querétaro, Qro. 76001 (Mexico)

    2014-08-01

    In this paper we report a low temperature sol–gel deposition process of PMMA–SiO{sub 2} hybrid films, with variable dielectric properties depending on the composition of the precursor solution, for applications to gate dielectric layers in field-effect thin film transistors (FE-TFT). The hybrid layers were processed by a modified sol–gel route using as precursors Tetraethyl orthosilicate (TEOS) and Methyl methacrylate (MMA), and 3-(Trimethoxysilyl)propyl methacrylate (TMSPM) as the coupling agent. Three types of hybrid films were processed with molar ratios of the precursors in the initial solution 1.0: 0.25, 0.50, 0.75: 1.0 for TEOS: TMSPM: MMA, respectively. The hybrid films were deposited by spin coating of the hybrid precursor solutions onto p-type Si (100) substrates and heat-treated at 90 °C for 24 h. The chemical bonding in the hybrid films was analyzed by Fourier Transform Infrared Spectroscopy to confirm their hybrid nature. The refractive index of the hybrid films as a function of the TMSPM coupling agent concentration, were determined from a simultaneous analysis of optical reflectance and spectroscopic ellipsometry experimental data. The PMMA–SiO{sub 2} hybrid films were studied as dielectric films using metal-insulator-metal structures. Capacitance–Voltage (C–V) and current–voltage (I–V) electrical methods were used to extract the dielectric properties of the different hybrid layers. The three types of hybrid films were tested as gate dielectric layers in thin film transistors with structure ZnO/PMMA–SiO{sub 2}/p-Si with a common bottom gate and patterned Al source/drain contacts, with different channel lengths. We analyzed the output electrical responses of the ZnO-based TFTs to determine their performance parameters as a function of channel length and hybrid gate dielectric layer. - Highlights: • PMMA–SiO{sub 2} hybrid films as dielectric material synthesized by sol–gel process at low temperature. • PMMA–SiO{sub 2

  5. Fission-fragment detector for DANCE based on thin scintillating films

    Science.gov (United States)

    Rusev, G.; Roman, A. R.; Daum, J. K.; Springs, R. K.; Bond, E. M.; Jandel, M.; Baramsai, B.; Bredeweg, T. A.; Couture, A.; Favalli, A.; Ianakiev, K. D.; Iliev, M. L.; Mosby, S.; Ullmann, J. L.; Walker, C. L.

    2015-12-01

    A fission-fragment detector based on thin scintillating films has been built to serve as a trigger/veto detector in neutron-induced fission measurements at DANCE. The fissile material is surrounded by scintillating films providing 4 π detection of the fission fragments. The scintillation photons were registered with silicon photomultipliers. A measurement of the 235U (n , f) reaction with this detector at DANCE revealed a correct time-of-flight spectrum and provided an estimate for the efficiency of the prototype detector of 11.6(7)%. Design and test measurements with the detector are described.

  6. The fabrication and characterization of nano-SQUIDs based on Nb thin films

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xixi; Liu, Xiaoyu; Wang, Hao; Chen, Lei, E-mail: leichen@mail.sim.ac.cn; Wang, Zhen

    2015-08-15

    Highlights: • We developed a nano-SQUID fabrication process starting from a high-quality thin film. • The fabricated nano-SQUIDs exhibited flux modulation depth up to 10.3% at 4.6 K. • The measured data agreed with the Ginzburg–Landau simulation. • We found that a small critical current <50 μA is important for a deep flux modulation. • The suggestions in improving the nano-SQUID’s performance were discussed. - Abstract: SQUIDs with nano-junctions (or nano-SQUIDs) are able to be miniaturized into nanoscale to measure a single Bohr magneton. Here, we reported the development of a fabrication process for Nb (niobium) nano-SQUIDs using the thin film deposition and the electron-beam lithography technology. The developed process started from a high-quality superconducting thin film so that it is compatible with a variety of film growing techniques. The as-fabricated nano-SQUIDs exhibited functional flux modulation depth up to 10.3% at 4.6 K, in agreement with the numerical simulation based on the Ginzburg–Landau equation. By further comparing the results from both experiments and simulations, we found that a small critical current below ∼50 μA played a leading role in order to obtain a decent flux-modulation depth for Nb nano-SQUIDs.

  7. Thin film metal-oxides

    CERN Document Server

    Ramanathan, Shriram

    2009-01-01

    Presents an account of the fundamental structure-property relations in oxide thin films. This title discusses the functional properties of thin film oxides in the context of applications in the electronics and renewable energy technologies.

  8. Thin films for material engineering

    Science.gov (United States)

    Wasa, Kiyotaka

    2016-07-01

    Thin films are defined as two-dimensional materials formed by condensing one by one atomic/molecular/ionic species of matter in contrast to bulk three-dimensional sintered ceramics. They are grown through atomic collisional chemical reaction on a substrate surface. Thin film growth processes are fascinating for developing innovative exotic materials. On the basis of my long research on sputtering deposition, this paper firstly describes the kinetic energy effect of sputtered adatoms on thin film growth and discusses on a possibility of room-temperature growth of cubic diamond crystallites and the perovskite thin films of binary compound PbTiO3. Secondly, high-performance sputtered ferroelectric thin films with extraordinary excellent crystallinity compatible with MBE deposited thin films are described in relation to a possible application for thin-film MEMS. Finally, the present thin-film technologies are discussed in terms of a future material science and engineering.

  9. Rare Earth Oxide Thin Films

    CERN Document Server

    Fanciulli, Marco

    2007-01-01

    Thin rare earth (RE) oxide films are emerging materials for microelectronic, nanoelectronic, and spintronic applications. The state-of-the-art of thin film deposition techniques as well as the structural, physical, chemical, and electrical properties of thin RE oxide films and of their interface with semiconducting substrates are discussed. The aim is to identify proper methodologies for the development of RE oxides thin films and to evaluate their effectiveness as innovative materials in different applications.

  10. NMR characterization of thin films

    Science.gov (United States)

    Gerald, II, Rex E.; Klingler, Robert J.; Rathke, Jerome W.; Diaz, Rocio; Vukovic, Lela

    2008-11-25

    A method, apparatus, and system for characterizing thin film materials. The method, apparatus, and system includes a container for receiving a starting material, applying a gravitational force, a magnetic force, and an electric force or combinations thereof to at least the starting material, forming a thin film material, sensing an NMR signal from the thin film material and analyzing the NMR signal to characterize the thin film of material.

  11. Selective inorganic thin films

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, M.L.F.; Weisenbach, L.A.; Anderson, M.T. [Sandia National Laboratories, Albuquerque, NM (United States)] [and others

    1995-05-01

    This project is developing inorganic thin films as membranes for gas separation applications, and as discriminating coatings for liquid-phase chemical sensors. Our goal is to synthesize these coatings with tailored porosity and surface chemistry on porous substrates and on acoustic and optical sensors. Molecular sieve films offer the possibility of performing separations involving hydrogen, air, and natural gas constituents at elevated temperatures with very high separation factors. We are focusing on improving permeability and molecular sieve properties of crystalline zeolitic membranes made by hydrothermally reacting layered multicomponent sol-gel films deposited on mesoporous substrates. We also used acoustic plate mode (APM) oscillator and surface plasmon resonance (SPR) sensor elements as substrates for sol-gel films, and have both used these modified sensors to determine physical properties of the films and have determined the sensitivity and selectivity of these sensors to aqueous chemical species.

  12. Protein Thin Film Machines

    OpenAIRE

    Federici, Stefania; Oliviero, Giulio; Hamad-Schifferli, Kimberly; Bergese, Paolo

    2010-01-01

    We report the first example of microcantilever beams that are reversibly driven by protein thin film machines fuelled by cycling the salt concentration of the surrounding solution. We also show that upon the same salinity stimulus the drive can be completely reversed in its direction by introducing a surface coating ligand. Experimental results are throughout discussed within a general yet simple thermodynamic model.

  13. InGaN-based thin film solar cells: Epitaxy, structural design, and photovoltaic properties

    Energy Technology Data Exchange (ETDEWEB)

    Sang, Liwen, E-mail: SANG.Liwen@nims.go.jp [International Center for Material Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); JST-PRESTO, The Japan Science and Technology Agency, Tokyo 102-0076 (Japan); Liao, Meiyong; Koide, Yasuo [Wide Bandgap Materials Group, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Sumiya, Masatomo [Wide Bandgap Materials Group, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); JST-ALCA, The Japan Science and Technology Agency, Tokyo 102-0076 (Japan)

    2015-03-14

    In{sub x}Ga{sub 1−x}N, with the tunable direct bandgaps from ultraviolet to near infrared region, offers a promising candidate for the high-efficiency next-generation thin-film photovoltaic applications. Although the adoption of thick InGaN film as the active region is desirable to obtain efficient light absorption and carrier collection compared to InGaN/GaN quantum wells structure, the understanding on the effect from structural design is still unclear due to the poor-quality InGaN films with thickness and difficulty of p-type doping. In this paper, we comprehensively investigate the effects from film epitaxy, doping, and device structural design on the performances of the InGaN-based solar cells. The high-quality InGaN thick film is obtained on AlN/sapphire template, and p-In{sub 0.08}Ga{sub 0.92}N is achieved with a high hole concentration of more than 10{sup 18 }cm{sup −3}. The dependence of the photovoltaic performances on different structures, such as active regions and p-type regions is analyzed with respect to the carrier transport mechanism in the dark and under illumination. The strategy of improving the p-i interface by using a super-thin AlN interlayer is provided, which successfully enhances the performance of the solar cells.

  14. Nanotribological Behavior of Carbon Based Thin Films: Friction and Lubricity Mechanisms at the Nanoscale

    Directory of Open Access Journals (Sweden)

    Costas A. Charitidis

    2013-04-01

    Full Text Available The use of materials with very attractive friction and wear properties has raised much attention in research and industrial sectors. A wide range of tribological applications, including rolling and sliding bearings, machining, mechanical seals, biomedical implants and microelectromechanical systems (MEMS, require thin films with high mechanical strength, chemical inertness, broad optical transparency, high refractive index, wide bandgap excellent thermal conductivity and extremely low thermal expansion. Carbon based thin films like diamond, diamond-like carbon, carbon nitride and cubic boron nitride known as “super-hard” material have been studied thoroughly as the ideal candidate for tribological applications. In this study, the results of experimental and simulation works on the nanotribological behavior of carbon films and fundamental mechanisms of friction and lubricity at the nano-scale are reviewed. The study is focused on the nanomechanical properties and analysis of the nanoscratching processes at low loads to obtain quantitative analysis, the comparison obtain quantitative analysis, the comparison of their elastic/plastic deformation response, and nanotribological behavior of the a-C, ta-C, a-C:H, CNx, and a-C:M films. For ta-C and a-C:M films new data are presented and discussed.

  15. Materials science and fabrication processes for a new MEMS technology based on ultrananocrystalline diamond thin films

    International Nuclear Information System (INIS)

    Most MEMS devices are currently based on silicon because of the available surface machining technology. However, Si has poor mechanical and tribological properties which makes it difficult to produce high performance Si based MEMS devices that could work reliably, particularly in harsh environments; diamond, as a superhard material with high mechanical strength, exceptional chemical inertness, outstanding thermal stability and superior tribological performance, could be an ideal material for MEMS. A key challenge for diamond MEMS is the integration of diamond films with other materials. Conventional CVD thin film deposition methods produce diamond films with large grains, high internal stress, poor intergranular adhesion and very rough surfaces, and are consequently ill-suited for MEMS applications. Diamond-like films offer an alternative, but are deposited using physical vapour deposition methods unsuitable for conformal deposition on high aspect ratio features, and generally they do not exhibit the outstanding mechanical properties of diamond. We describe a new ultrananocrystalline diamond (UNCD) film technology based on a microwave plasma technique using argon plasma chemistries that produce UNCD films with morphological and mechanical properties that are ideally suited for producing reliable MEMS devices. We have developed lithographic techniques for the fabrication of UNCD MEMS components, including cantilevers and multilevel devices, acting as precursors to micro-bearings and gears, making UNCD a promising material for the development of high performance MEMS devices. We also review the mechanical, tribological, electronic transport, chemical and biocompatibility properties of UNCD, which make this an ideal material for reliable, long endurance MEMS device use. (topical review)

  16. Electrical characterization of graphene oxide and organic dielectric layers based on thin film transistor

    International Nuclear Information System (INIS)

    Highlights: • We report the synthesis of graphene oxide nanosheets and electrical characterization of graphene oxide based thin film transistor. • Graphene oxide (GO) nanosheets were prepared by using modified Hummers method. • We used insulator layers which are polymethylmethacrylate (PMMA) and polyvinyl phenol (PVP) for graphene oxide based thin flim transistor. - Abstract: We have studied the electrical characteristics of graphene oxide based thin flim transistor with the polymer insulators such as polymethyl methacrylate (PMMA) and poly-4-vinylphenol (PVP). Graphene oxide (GO) nanosheets were prepared by using modified Hummers method. The structural properties of GO nanosheets were characterized with Ultraviolet Visible (UV–vis), FT-IR spectroscopy and X-rays diffraction (XRD). Graphene oxide based thin flim transistor (GO-TFT) was prepared by a spin-coating and thermal evaporation technique. The electrical characterization of GO-TFT was analyzed by output and transfer characteristics by using Keithley-4200 semiconductor characterization system (SCS). The graphene oxide based thin flim transistor devices show p-type semiconducting behavior. The mobility, threshold voltage, sub-threshold swing value and Ion/Ioff of GO-TFT were found to be 0.105 cm2 V−1 s−1, −8.7 V, 4.03 V/decade and 10, respectively

  17. Nanoscale Ta-based diffusion barrier thin-films and their resistance properties

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Nanoscale Ta-based diffusion barrier thin-films and Cu/barrier/Si multilayer structures were deposited on p-type Si (100) substrates by DC magnetron sputtering. Then the samples were rapidly thermal-annealed (RTA) by tungsten halide lamp. The resistance properties, structure and surface morphology of the thin-films were investigated by four-point probe (FPP) sheet resistance measurement, AFM, SEM-EDS, Alpha-Step IQ Profilers and XRD. The experimental results showed that agglomeration, oxidation and stabilization effects are concurrent. And resistance increasing and decreasing are coexistent after RTA. The formation of high resistance Cu3Si due to inter-diffusion between Cu and Si and more intensive electron scattering resulting from rougher surface caused the sheet resistance to increase abruptly after high temperature RTA.

  18. Graphene oxide/carbon nanoparticle thin film based IR detector: Surface properties and device characterization

    Energy Technology Data Exchange (ETDEWEB)

    Chowdhury, Farzana Aktar [Experimental Physics Division, Atomic Energy Centre, 4, Kazi Nazrul Islam Avenue, Dhaka-1000 (Bangladesh); Hossain, Mohammad Abul [Department of Chemistry, Faculty of Science, University of Dhaka, Dhaka-1000 (Bangladesh); Uchida, Koji; Tamura, Takahiro; Sugawa, Kosuke; Mochida, Tomoaki; Otsuki, Joe [College of Science and Technology, Nihon University, 1-8-14 Kanda Surugadai, Chiyoda-ku, Tokyo 101-8308 (Japan); Mohiuddin, Tariq [Department of Physics, College of Science, Sultan Qaboos University, Muscat (Oman); Boby, Monny Akter [Department of Physics, Faculty of Science, University of Dhaka, Dhaka-1000 (Bangladesh); Alam, Mohammad Sahabul, E-mail: msalam@ksu.edu.sa [Department of Physics, Faculty of Science, University of Dhaka, Dhaka-1000 (Bangladesh); Department of Chemical Engineering, College of Engineering & King Abdullah Institute for Nanotechnology, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia)

    2015-10-15

    This work deals with the synthesis, characterization, and application of carbon nanoparticles (CNP) adorned graphene oxide (GO) nanocomposite materials. Here we mainly focus on an emerging topic in modern research field presenting GO-CNP nanocomposite as a infrared (IR) radiation detector device. GO-CNP thin film devices were fabricated from liquid phase at ambient condition where no modifying treatments were necessary. It works with no cooling treatment and also for stationary objects. A sharp response of human body IR radiation was detected with time constants of 3 and 36 sec and radiation responsivity was 3 mAW{sup −1}. The current also rises for quite a long time before saturation. This work discusses state-of-the-art material developing technique based on near-infrared photon absorption and their use in field deployable instrument for real-world applications. GO-CNP-based thin solid composite films also offer its potentiality to be utilized as p-type absorber material in thin film solar cell, as well.

  19. Graphene oxide/carbon nanoparticle thin film based IR detector: Surface properties and device characterization

    Science.gov (United States)

    Chowdhury, Farzana Aktar; Hossain, Mohammad Abul; Uchida, Koji; Tamura, Takahiro; Sugawa, Kosuke; Mochida, Tomoaki; Otsuki, Joe; Mohiuddin, Tariq; Boby, Monny Akter; Alam, Mohammad Sahabul

    2015-10-01

    This work deals with the synthesis, characterization, and application of carbon nanoparticles (CNP) adorned graphene oxide (GO) nanocomposite materials. Here we mainly focus on an emerging topic in modern research field presenting GO-CNP nanocomposite as a infrared (IR) radiation detector device. GO-CNP thin film devices were fabricated from liquid phase at ambient condition where no modifying treatments were necessary. It works with no cooling treatment and also for stationary objects. A sharp response of human body IR radiation was detected with time constants of 3 and 36 sec and radiation responsivity was 3 mAW-1. The current also rises for quite a long time before saturation. This work discusses state-of-the-art material developing technique based on near-infrared photon absorption and their use in field deployable instrument for real-world applications. GO-CNP-based thin solid composite films also offer its potentiality to be utilized as p-type absorber material in thin film solar cell, as well.

  20. Miniaturized and reconfigurable notch antenna based on a BST ferroelectric thin film

    International Nuclear Information System (INIS)

    Highlights: • A miniature and agile antenna based on a BST MIM capacitor is simulated and made. • Mn2+ doped BST thin films are synthesized by chemical deposition and spin coating. • Permittivity and losses of the BST thin film are respectively 225 and 0.02 at 1 GHz. • A miniaturization rate of 70% is obtained with a MIM capacitance of 3.7 pF. • A frequency tunability of 14.5% and a tunability performance of 0.04 are measured. - Abstract: This work deals with the design, realization and characterization of a miniature and frequency agile antenna based on a ferroelectric Ba0,80Sr0,20TiO3 thin film. The notch antenna is loaded with a variable metal/insulator/metal (MIM) capacitor and is achieved by a monolithic method. The MIM capacitance is 3.7 pF, which results in a resonant frequency of 670 MHz compared to 2.25 GHz for the unloaded simulated antenna; the resulting miniaturization rate is 70%. The characterization of the antenna prototype shows a frequency tunable rate of 14.5% under an electric field of 375 kV/cm, with a tunability performance η = 0.04

  1. Fabrication and characteristics of magnetic field sensors based on nano-polysilicon thin-film transistors

    Institute of Scientific and Technical Information of China (English)

    Zhao Xiaofeng; Wen Dianzhong; Zhuang Cuicui; Cao Jingya; Wang Zhiqiang

    2013-01-01

    A magnetic field sensor based on nano-polysilicon thin films transistors (TFTs) with Hall probes is proposed.The magnetic field sensors are fabricated on 〈100〉 orientation high resistivity (ρ > 500 Ω·cm) silicon substrates by using CMOS technology,which adopt nano-polysilicon thin films with thicknesses of 90 nm and heterojunction interfaces between the nano-polysilicon thin films and the high resistivity silicon substrates as the sensing layers.The experimental results show that when VDS =5.0 V,the magnetic sensitivities of magnetic field sensors based on nano-polysilicon TFTs with length-width ratios of 160 μm/80 μm,320 μm/80 μm and 480 μm/80μm are 78 mV/T,55 mV/T and 34 mV/T,respectively.Under the same conditions,the magnetic sensitivity of the obtained magnetic field sensor is significantly improved in comparison with a Hall magnetic field sensor adopting silicon as the sensing layers.

  2. Graphene oxide/carbon nanoparticle thin film based IR detector: Surface properties and device characterization

    Directory of Open Access Journals (Sweden)

    Farzana Aktar Chowdhury

    2015-10-01

    Full Text Available This work deals with the synthesis, characterization, and application of carbon nanoparticles (CNP adorned graphene oxide (GO nanocomposite materials. Here we mainly focus on an emerging topic in modern research field presenting GO-CNP nanocomposite as a infrared (IR radiation detector device. GO-CNP thin film devices were fabricated from liquid phase at ambient condition where no modifying treatments were necessary. It works with no cooling treatment and also for stationary objects. A sharp response of human body IR radiation was detected with time constants of 3 and 36 sec and radiation responsivity was 3 mAW−1. The current also rises for quite a long time before saturation. This work discusses state-of-the-art material developing technique based on near-infrared photon absorption and their use in field deployable instrument for real-world applications. GO-CNP-based thin solid composite films also offer its potentiality to be utilized as p-type absorber material in thin film solar cell, as well.

  3. Miniaturized and reconfigurable notch antenna based on a BST ferroelectric thin film

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Hung Viet [Institut d' Electronique et de Télécommunications de Rennes (IETR), IUT Saint-Brieuc, Université de Rennes 1, 22004 Saint-Brieuc (France); CEA-LETI, Minatec, 17 avenue des Martyrs, 38054 Grenoble Cedex 9 (France); Benzerga, Ratiba, E-mail: ratiba.benzerga@univ-rennes1.fr [Institut d' Electronique et de Télécommunications de Rennes (IETR), IUT Saint-Brieuc, Université de Rennes 1, 22004 Saint-Brieuc (France); Borderon, Caroline [IETR, Université de Nantes, 2 rue de la Houssinière, 44322 Nantes (France); Delaveaud, Christophe [CEA-LETI, Minatec, 17 avenue des Martyrs, 38054 Grenoble Cedex 9 (France); Sharaiha, Ala [Institut d' Electronique et de Télécommunications de Rennes (IETR), IUT Saint-Brieuc, Université de Rennes 1, 22004 Saint-Brieuc (France); Renoud, Raphael [IETR, Université de Nantes, 2 rue de la Houssinière, 44322 Nantes (France); Paven, Claire Le [Institut d' Electronique et de Télécommunications de Rennes (IETR), IUT Saint-Brieuc, Université de Rennes 1, 22004 Saint-Brieuc (France); Pavy, Sabrina; Nadaud, Kevin; Gundel, Hartmut W. [IETR, Université de Nantes, 2 rue de la Houssinière, 44322 Nantes (France)

    2015-07-15

    Highlights: • A miniature and agile antenna based on a BST MIM capacitor is simulated and made. • Mn{sup 2+} doped BST thin films are synthesized by chemical deposition and spin coating. • Permittivity and losses of the BST thin film are respectively 225 and 0.02 at 1 GHz. • A miniaturization rate of 70% is obtained with a MIM capacitance of 3.7 pF. • A frequency tunability of 14.5% and a tunability performance of 0.04 are measured. - Abstract: This work deals with the design, realization and characterization of a miniature and frequency agile antenna based on a ferroelectric Ba{sub 0,80}Sr{sub 0,20}TiO{sub 3} thin film. The notch antenna is loaded with a variable metal/insulator/metal (MIM) capacitor and is achieved by a monolithic method. The MIM capacitance is 3.7 pF, which results in a resonant frequency of 670 MHz compared to 2.25 GHz for the unloaded simulated antenna; the resulting miniaturization rate is 70%. The characterization of the antenna prototype shows a frequency tunable rate of 14.5% under an electric field of 375 kV/cm, with a tunability performance η = 0.04.

  4. Ultraviolet photosensors based on ZnS thin films

    Directory of Open Access Journals (Sweden)

    Bobrenko Yu. N.

    2009-10-01

    Full Text Available High efficient photodiodes on the base of р-Cu1,8S/n-ZnS/(ZnSх(CdSe1–х/CdSe/Mo-structure with variband interlayer were fabricated. Optimization of this layer thickness was shown to be efficient method of reduction of photosensitivity behind UV region while preserving one in UV region.

  5. Thin film polymeric gel electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Derzon, Dora K. (1554 Rosalba St. NE., Albuquerque, Bernalillo County, NM 87112); Arnold, Jr., Charles (3436 Tahoe, NE., Albuquerque, Bernalillo County, NM 87111); Delnick, Frank M. (9700 Fleming Rd., Dexter, MI 48130)

    1996-01-01

    Novel hybrid thin film electrolyte, based on an organonitrile solvent system, which are compositionally stable, environmentally safe, can be produced efficiently in large quantity and which, because of their high conductivities .apprxeq.10.sup.-3 .OMEGA..sup.-1 cm.sup.-1 are useful as electrolytes for rechargeable lithium batteries.

  6. Ultimate form freedom in thin film solar cells by postmanufacture laser-based processing

    NARCIS (Netherlands)

    Gilot, J.; Emelin, B.; Galagan, Y.; Mandamparambil, R.; Andriessen, R.

    2015-01-01

    Thin film photovoltaics can be beneficial for specific applications like building integrated photovoltaics. To fully exploit the differentiator of form freedom, the interconnections in thin film modules can be tuned depending on the required module output. Traditionally, an alternation of coating an

  7. [Spectral emissivity of thin films].

    Science.gov (United States)

    Zhong, D

    2001-02-01

    In this paper, the contribution of multiple reflections in thin film to the spectral emissivity of thin films of low absorption is discussed. The expression of emissivity of thin films derived here is related to the thin film thickness d and the optical constants n(lambda) and k(lambda). It is shown that in the special case d-->infinity the emissivity of thin films is equivalent to that of the bulk material. Realistic numerical and more precise general numerical results for the dependence of the emissivity on d, n(lambda) and k(lambda) are given.

  8. Investigation of Tribological Behavior of Lanthanum-Based Thin Films Deposited on Sulfonated Self-Assembled Monolayer

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    3-mercaptopropyl trimethoxysilane (MPTS) was prepared on glass substrate so as to form a two-dimensional self-assembled monolayer (SAM), and the terminal -SH group in the film was in situ oxidized to -SO3H group to confer good chemisorption ability to the film. Thus, lanthanum-based thin films were deposited on oxidized MPTS-SAM, making use of the chemisorption ability of -SO3H group. Atomic force microscopy (AFM) and X-ray photoelectron spectrometry (XPS) and contact angle measurements were used to characterize the thin films. The tribological properties of the as-prepared thin films sliding against a steel ball were evaluated on a friction and wear tester. Tribological experiment shows that the friction coefficient of glass substrate decreases from 0.8 to 0.08 after the rare earth (RE) self-assembled films (SAMs) are formed on its surface. And the RE self-assembled films have longer wear life (500 sliding passes). It is demonstrated that RE self-assembled film exhibits good wear-resistant property. The marked decrease in friction and the longer wear life of RE films are attributed to the excellent adhesion of the film to the substrate and to the special characteristics of the RE elements. The frictional behaviors of RE thin-films-coated silicon surface were sensitive to the applied load and the sliding velocity of the steel ball.

  9. A Photonic Crystal Laser from Solution Based Organo-Lead Iodide Perovskite Thin Films.

    Science.gov (United States)

    Chen, Songtao; Roh, Kwangdong; Lee, Joonhee; Chong, Wee Kiang; Lu, Yao; Mathews, Nripan; Sum, Tze Chien; Nurmikko, Arto

    2016-04-26

    Perovskite semiconductors are actively investigated for high performance solar cells. Their large optical absorption coefficient and facile solution-based, low-temperature synthesis of thin films make perovskites also a candidate for light-emitting devices across the visible and near-infrared. Specific to their potential as optical gain medium for lasers, early work has demonstrated amplified spontaneous emission and lasing at attractively low thresholds of photoexcitation. Here, we take an important step toward practically usable perovskite lasers where a solution-processed thin film is embedded within a two-dimensional photonic crystal resonator. We demonstrate high degree of temporally and spatially coherent lasing whereby well-defined directional emission is achieved near 788 nm wavelength at optical pumping energy density threshold of 68.5 ± 3.0 μJ/cm(2). The measured power conversion efficiency and differential quantum efficiency of the perovskite photonic crystal laser are 13.8 ± 0.8% and 35.8 ± 5.4%, respectively. Importantly, our approach enables scalability of the thin film lasers to a two-dimensional multielement pixelated array of microlasers which we demonstrate as a proof-of-concept for possible projection display applications. PMID:26997122

  10. Chemical vapor deposition based tungsten disulfide (WS2) thin film transistor

    KAUST Repository

    Hussain, Aftab M.

    2013-04-01

    Tungsten disulfide (WS2) is a layered transition metal dichalcogenide with a reported band gap of 1.8 eV in bulk and 1.32-1.4 eV in its thin film form. 2D atomic layers of metal dichalcogenides have shown changes in conductivity with applied electric field. This makes them an interesting option for channel material in field effect transistors (FETs). Therefore, we show a highly manufacturable chemical vapor deposition (CVD) based simple process to grow WS2 directly on silicon oxide in a furnace and then its transistor action with back gated device with room temperature field effect mobility of 0.1003 cm2/V-s using the Schottky barrier contact model. We also show the semiconducting behavior of this WS2 thin film which is more promising than thermally unstable organic materials for thin film transistor application. Our direct growth method on silicon oxide also holds interesting opportunities for macro-electronics applications. © 2013 IEEE.

  11. Molecular group dynamics study on slip flow of thin fluid film based on the Hamaker hypotheses

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The thin fluid film was assumed to consist of a number of spherical fluid molecular groups and the attractive forces of molecular group pairs were calculated by the derived equation according to the three Hamaker homogeneous material hypotheses. Regarding each molecular group as a dynamics individual, the simulation method for the shearing motion of multilayer fluid molecular groups, which was initiated by two moving walls, was proposed based on the Verlet velocity iterative algorithm. The simulations reveal that the velocities of fluid molecular groups change about their respective mean velocities within a narrow range in steady state. It is also found that the velocity slips occur at the wall boundary and in a certain number of fluid film layers close to the wall. Because the dimension of molecular group and the number of group layers are not restricted, the hypothetical thickness of fluid film model can be enlarged from nanometer to micron by using the proposed simulation method.

  12. Thin film superconductor magnetic bearings

    Science.gov (United States)

    Weinberger, Bernard R.

    1995-12-26

    A superconductor magnetic bearing includes a shaft (10) that is subject to a load (L) and rotatable around an axis of rotation, a magnet (12) mounted to the shaft, and a stator (14) in proximity to the shaft. The stator (14) has a superconductor thin film assembly (16) positioned to interact with the magnet (12) to produce a levitation force on the shaft (10) that supports the load (L). The thin film assembly (16) includes at least two superconductor thin films (18) and at least one substrate (20). Each thin film (18) is positioned on a substrate (20) and all the thin films are positioned such that an applied magnetic field from the magnet (12) passes through all the thin films. A similar bearing in which the thin film assembly (16) is mounted on the shaft (10) and the magnet (12) is part of the stator (14) also can be constructed.

  13. Microscopic silicon-based lateral high-aspect-ratio structures for thin film conformality analysis

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Feng; Arpiainen, Sanna; Puurunen, Riikka L., E-mail: riikka.puurunen@vtt.fi [VTT Technical Research Centre of Finland, Tietotie 3, 02044 Espoo (Finland)

    2015-01-15

    Film conformality is one of the major drivers for the interest in atomic layer deposition (ALD) processes. This work presents new silicon-based microscopic lateral high-aspect-ratio (LHAR) test structures for the analysis of the conformality of thin films deposited by ALD and by other chemical vapor deposition means. The microscopic LHAR structures consist of a lateral cavity inside silicon with a roof supported by pillars. The cavity length (e.g., 20–5000 μm) and cavity height (e.g., 200–1000 nm) can be varied, giving aspect ratios of, e.g., 20:1 to 25 000:1. Film conformality can be analyzed with the microscopic LHAR by several means, as demonstrated for the ALD Al{sub 2}O{sub 3} and TiO{sub 2} processes from Me{sub 3}Al/H{sub 2}O and TiCl{sub 4}/H{sub 2}O. The microscopic LHAR test structures introduced in this work expose a new parameter space for thin film conformality investigations expected to prove useful in the development, tuning and modeling of ALD and other chemical vapor deposition processes.

  14. Copper Oxide Thin Films through Solution Based Methods for Electrical Energy Conversion and Storage

    Science.gov (United States)

    Zhu, Changqiong

    Copper oxides (Cu2O and CuO), composed of non-toxic and earth abundant elements, are promising materials for electrical energy generation and storage devices. Solution based techniques for creating thin films of these materials, such as electrodeposition, are important to understand and develop because of their potential for realizing substantial energy savings compared to traditional fabrication methods. Cuprous oxide (Cu2O), with its direct band gap, is a p-type semiconductor that is well suited for creating solution-processed photovoltaic devices (solar cells); several key advancements made toward this application are the primary focus of this thesis. Electrodeposition of single-phase, crystalline Cu2O thin films is demonstrated using previously unexplored, acidic lactate/Cu2+ solutions, which has provided additional understanding of the impacts of growth solution chemistry on film formation. The influence of pH on the resulting Cu2O thin film properties is revealed by using the same ligand (sodium lactate) at various solution pH values. Cu2O films grown from acidic lactate solutions can exhibit a distinctive flowerlike, dendritic morphology, in contrast to the faceted, dense films obtained using alkaline lactate solutions. Relative speciation distributions of the various metal complex ions present under different growth conditions are calculated using reported equilibrium association constants and experimentally supported by UV-Visible absorption spectroscopy. Dependence of thin film morphology on the lactate/Cu2+ molar ratio and applied potential is described. Cu2O/eutectic gallium-indium Schottky junction devices are formed and devices are tested under monochromatic green LED illumination. Further surface examination of the Cu2O films using X-ray photoelectron spectroscopy (XPS) reveals the fact that films grown from acidic lactate solution with a small lactate/Cu2+ molar ratio, which exhibit improved photovoltaic performance compared to films grown from

  15. The development of potassium tantalate niobate thin films for satellite-based pyroelectric detectors

    Energy Technology Data Exchange (ETDEWEB)

    Cherry, H B.B. [Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering

    1997-05-01

    Potassium tantalate niobate (KTN) pyroelectric detectors are expected to provide detectivities, of 3.7 x 10{sup 11} cmHz {sup {1/2}}W{sup {minus}1} for satellite-based infrared detection at 90 K. The background limited detectivity for a room-temperature thermal detector is 1.8 x 10{sup 10} cmHz{sup {1/2}}W{sup {minus}1}. KTN is a unique ferroelectric for this application because of the ability to tailor the temperature of its pyroelectric response by adjusting its ratio of tantalum to niobium. The ability to fabricate high quality KTN thin films on Si-based substrates is crucial to the development of KTN pyroelectric detectors. Si{sub x}N{sub y} membranes created on the Si substrate will provide the weak thermal link necessary to reach background limited detectivities. The device dimensions obtainable by thin film processing are expected to increase the ferroelectric response by 20 times over bulk fabricated KTN detectors. In addition, microfabrication techniques allow for easier array development. This is the first reported attempt at growth of KTN films on Si-based substrates. Pure phase perovskite films were grown by pulsed laser deposition on SrRuO{sub 3}/Pt/Ti/Si{sub x}N{sub y}/Si and SrRuO{sub 3}/Si{sub x}N{sub y}/Si structures; room temperature dielectric permittivities for the KTN films were 290 and 2.5, respectively. The dielectric permittivity for bulk grown, single crystal KTN is {approximately}380. In addition to depressed dielectric permittivities, no ferroelectric hysteresis was found between 80 and 300 K for either structure. RBS, AES, TEM and multi-frequency dielectric measurements were used to investigate the origin of this apparent lack of ferroelectricity. Other issues addressed by this dissertation include: the role of oxygen and target density during pulsed laser deposition of KTN thin films; the use of YBCO, LSC and Pt as direct contact bottom electrodes to the KTN films, and the adhesion of the bottom electrode layers to Si{sub x}N{sub y}/Si.

  16. Nanocomposite thin films for miniaturized multi-ayer ceramic capacitors prepared from barium titanate nanoparticle based hybrid solutions

    OpenAIRE

    Schneller, T.; Halder, S; Waser, R.; Pithan, C.; Dornseiffer, J.; Shiratori, Y; Houben, L.; Vyshnavi, N.; Majumber, S.B.

    2011-01-01

    In the present work a flexible approach for the wet chemical processing of nanocomposite functional thin films is demonstrated. Barium titanate (BTO) based nanocomposite thin films for future miniaturized multi-layer ceramic capacitors are chosen as model systems to introduce the concept of "hybrid solutions" which consist of stabile mixtures of reverse micelle derived BTO nanoparticle dispersions and conventional molecular precursor solutions of either the same (BTO:BTO) or a specifically di...

  17. Biomimetic thin film deposition

    Energy Technology Data Exchange (ETDEWEB)

    Rieke, P.R.; Graff, G.E.; Campbell, A.A.; Bunker, B.C.; Baskaran, S.; Song, L.; Tarasevich, B.J.; Fryxell, G.E.

    1995-09-01

    Biological mineral deposition for the formation of bone, mollusk shell and other hard tissues provides materials scientists with illustrative materials processing strategies. This presentation will review the key features of biomineralization and how these features can be of technical importance. We have adapted existing knowledge of biomineralization to develop a unique method of depositing inorganic thin films and coating. Our approach to thin film deposition is to modify substrate surfaces to imitate the proteins found in nature that are responsible for controlling mineral deposition. These biomimetic surfaces control the nucleation and growth of the mineral from a supersaturated aqueous solution. This has many processing advantages including simple processing equipment, environmentally benign reagents, uniform coating of highly complex shapes, and enhanced adherence of coating. Many different types of metal oxide, hydroxide, sulfide and phosphate materials with useful mechanical, optical, electronic and biomedical properties can be deposited.

  18. Optical absorbers based on strong interference in ultra-thin films

    CERN Document Server

    Kats, Mikhail A

    2016-01-01

    Optical absorbers find uses in a wide array of applications across the electromagnetic spectrum, including photovoltaic and photochemical cells, photodetectors, optical filters, stealth technology, and thermal light sources. Recent efforts have sought to reduce the footprint of optical absorbers, conventionally based on graded structures or Fabry-Perot-type cavities, by using the emerging concepts of plasmonics, metamaterials, and metasurfaces. Unfortunately, these new absorber designs require patterning on subwavelength length scales, and are therefore impractical for many large-scale optical and optoelectronic devices. In this article, we summarize recent progress in the development of optical absorbers based on lossy films with thicknesses significantly smaller than the incident optical wavelength. These structures have a small footprint and require no nanoscale patterning. We outline the theoretical foundation of these absorbers based on "ultra-thin-film interference", including the concepts of loss-induc...

  19. Thin film processes

    CERN Document Server

    Vossen, John L

    1978-01-01

    Remarkable advances have been made in recent years in the science and technology of thin film processes for deposition and etching. It is the purpose of this book to bring together tutorial reviews of selected filmdeposition and etching processes from a process viewpoint. Emphasis is placed on the practical use of the processes to provide working guidelines for their implementation, a guide to the literature, and an overview of each process.

  20. Hydrogenated amorphous silicon sensors based on thin film on ASIC technology

    CERN Document Server

    Despeisse, M; Anelli, G; Jarron, P; Kaplon, J; Rusack, R; Saramad, S; Wyrsch, N

    2006-01-01

    The performance and limitations of a novel detector technology based on the deposition of a thin-film sensor on top of processed integrated circuits have been studied. Hydrogenated amorphous silicon (a-Si:H) films have been deposited on top of CMOS circuits developed for these studies and the resulting "thin-film on ASIC" (TFA) detectors are presented. The leakage current of the a-Si:H sensor at high reverse biases turns out to be an important parameter limiting the performance of a TFA detector. Its detailed study and the pixel segmentation of the detector are presented. High internal electric fields (in the order of 10/sup 4/-10/sup 5/ V/cm) can be built in the a-Si:H sensor and overcome the low mobility of electrons and holes in a-Si:H. Signal induction by generated carrier motion and speed in the a-Si:H sensor have been studied with a 660 nm pulsed laser on a TFA detector based on an ASIC integrating 5 ns peaking time pre- amplifiers. The measurement set-up also permits to study the depletion of the senso...

  1. Ultrastrong, Chemically Resistant Reduced Graphene Oxide-based Multilayer Thin Films with Damage Detection Capability.

    Science.gov (United States)

    Guin, Tyler; Stevens, Bart; Krecker, Michelle; D'Angelo, John; Humood, Mohammad; Song, Yixuan; Smith, Ryan; Polycarpou, Andreas; Grunlan, Jaime C

    2016-03-01

    Multilayer thin films of graphene oxide (GO) and poly(vinylamine) (PVAm) were deposited via layer-by-layer assembly. Poly(vinylamine) pH was used to tailor film thickness and GO layer spacing. Graphene oxide concentration in the films was controlled through simple pH adjustment. Thermal reduction of the PVAm/GO multilayer thin films rendered them electrically conductive, which could be further tailored with PVAm pH. These reduced films also exhibited exceptionally high elastic modulus of 30 GPa and hardness of 1.8 GPa, which are among the highest of any graphene-filled polymer composite values ever reported. Cross-linking of these films with glutaraldehyde improved their chemical resistance, allowing them to survive strongly acidic or salty solutions. Additionally, scratches in the films can be instantaneously detected by a simple electrical resistance measurement. These films are promising for a variety of packaging and electronic applications. PMID:26885558

  2. Thin film interconnect processes

    Science.gov (United States)

    Malik, Farid

    Interconnects and associated photolithography and etching processes play a dominant role in the feature shrinkage of electronic devices. Most interconnects are fabricated by use of thin film processing techniques. Planarization of dielectrics and novel metal deposition methods are the focus of current investigations. Spin-on glass, polyimides, etch-back, bias-sputtered quartz, and plasma-enhanced conformal films are being used to obtain planarized dielectrics over which metal films can be reliably deposited. Recent trends have been towards chemical vapor depositions of metals and refractory metal silicides. Interconnects of the future will be used in conjunction with planarized dielectric layers. Reliability of devices will depend to a large extent on the quality of the interconnects.

  3. Thin film mechanics

    Science.gov (United States)

    Cooper, Ryan C.

    This doctoral thesis details the methods of determining mechanical properties of two classes of novel thin films suspended two-dimensional crystals and electron beam irradiated microfilms of polydimethylsiloxane (PDMS). Thin films are used in a variety of surface coatings to alter the opto-electronic properties or increase the wear or corrosion resistance and are ideal for micro- and nanoelectromechanical system fabrication. One of the challenges in fabricating thin films is the introduction of strains which can arise due to application techniques, geometrical conformation, or other spurious conditions. Chapters 2-4 focus on two dimensional materials. This is the intrinsic limit of thin films-being constrained to one atomic or molecular unit of thickness. These materials have mechanical, electrical, and optical properties ideal for micro- and nanoelectromechanical systems with truly novel device functionality. As such, the breadth of applications that can benefit from a treatise on two dimensional film mechanics is reason enough for exploration. This study explores the anomylously high strength of two dimensional materials. Furthermore, this work also aims to bridge four main gaps in the understanding of material science: bridging the gap between ab initio calculations and finite element analysis, bridging the gap between ab initio calculations and experimental results, nanoscale to microscale, and microscale to mesoscale. A nonlinear elasticity model is used to determine the necessary elastic constants to define the strain-energy density function for finite strain. Then, ab initio calculations-density functional theory-is used to calculate the nonlinear elastic response. Chapter 2 focuses on validating this methodology with atomic force microscope nanoindentation on molybdenum disulfide. Chapter 3 explores the convergence criteria of three density functional theory solvers to further verify the numerical calculations. Chapter 4 then uses this model to investigate

  4. A Review on Development Prospect of CZTS Based Thin Film Solar Cells

    Directory of Open Access Journals (Sweden)

    Xiangbo Song

    2014-01-01

    Full Text Available Cu2ZnSnS4 is considered as the ideal absorption layer material in next generation thin film solar cells due to the abundant component elements in the crust being nontoxic and environmentally friendly. This paper summerized the development situation of Cu2ZnSnS4 thin film solar cells and the manufacturing technologies, as well as problems in the manufacturing process. The difficulties for the raw material’s preparation, the manufacturing process, and the manufacturing equipment were illustrated and discussed. At last, the development prospect of Cu2ZnSnS4 thin film solar cells was commented.

  5. Room-temperature fabrication of light-emitting thin films based on amorphous oxide semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Junghwan, E-mail: JH.KIM@lucid.msl.titech.ac.jp; Miyokawa, Norihiko; Ide, Keisuke [Materials and Structures Laboratory, Tokyo Institute of Technology, Mailbox R3-4, 4259 Nagatsuta, Midori-ku, Yokohama (Japan); Toda, Yoshitake [Materials Research Center for Element Strategy, Tokyo Institute of Technology, Mailbox SE-6, 4259 Nagatsuta, Midori-ku, Yokohama (Japan); Hiramatsu, Hidenori; Hosono, Hideo; Kamiya, Toshio [Materials and Structures Laboratory, Tokyo Institute of Technology, Mailbox R3-4, 4259 Nagatsuta, Midori-ku, Yokohama (Japan); Materials Research Center for Element Strategy, Tokyo Institute of Technology, Mailbox SE-6, 4259 Nagatsuta, Midori-ku, Yokohama (Japan)

    2016-01-15

    We propose a light-emitting thin film using an amorphous oxide semiconductor (AOS) because AOS has low defect density even fabricated at room temperature. Eu-doped amorphous In-Ga-Zn-O thin films fabricated at room temperature emitted intense red emission at 614 nm. It is achieved by precise control of oxygen pressure so as to suppress oxygen-deficiency/excess-related defects and free carriers. An electronic structure model is proposed, suggesting that non-radiative process is enhanced mainly by defects near the excited states. AOS would be a promising host for a thin film phosphor applicable to flexible displays as well as to light-emitting transistors.

  6. Electrostatic thin film chemical and biological sensor

    Science.gov (United States)

    Prelas, Mark A.; Ghosh, Tushar K.; Tompson, Jr., Robert V.; Viswanath, Dabir; Loyalka, Sudarshan K.

    2010-01-19

    A chemical and biological agent sensor includes an electrostatic thin film supported by a substrate. The film includes an electrostatic charged surface to attract predetermined biological and chemical agents of interest. A charge collector associated with said electrostatic thin film collects charge associated with surface defects in the electrostatic film induced by the predetermined biological and chemical agents of interest. A preferred sensing system includes a charge based deep level transient spectroscopy system to read out charges from the film and match responses to data sets regarding the agents of interest. A method for sensing biological and chemical agents includes providing a thin sensing film having a predetermined electrostatic charge. The film is exposed to an environment suspected of containing the biological and chemical agents. Quantum surface effects on the film are measured. Biological and/or chemical agents can be detected, identified and quantified based on the measured quantum surface effects.

  7. TiO2 thin film based transparent flexible resistive switching random access memory

    Science.gov (United States)

    Pham, Kim Ngoc; Dung Hoang, Van; Tran, Cao Vinh; Thang Phan, Bach

    2016-03-01

    In our work we have fabricated TiO2 based resistive switching devices both on transparent substrates (ITO, IGZO/glass) and transparent flexible substrate (ITO/PET). All devices demonstrate the reproducibility of forming free bipolar resistive switching with high transparency in the visible light range (∼80% at the wavelength of 550 nm). Particularly, transparent and flexible device exhibits stable resistive switching performance at the initial state (flat) and even after bending state up to 500 times with curvature radius of 10% compared to flat state. The achieved characteristics of resistive switching of TiO2 thin films seem to be promising for transparent flexible random access memory.

  8. Preparation of GaN-on-Si based thin-film flip-chip LEDs

    Institute of Scientific and Technical Information of China (English)

    Zhang Shaohua; Feng Bo; Sun Qian; Zhao Hanmin

    2013-01-01

    GaN based MQW epitaxial layers were grown on Si (111) substrate by MOCVD using A1N as the buffer layer.High light extraction LEDs were prepared by substrate transferring technology in combination with thin-film and flip-chip design.The blue and white 1.1 × 1.1 mm2 LED lamps are measured.The optical powers and external quantum efficiency for silicone encapsulated blue lamp are 546 mW,and 50.3% at forward current of 350 mA,while the photometric light output for a white lamp packaged with standard YAG phosphor is 120.1 lm.

  9. A physical surface-potential-based drain current model for polysilicon thin-film transistors

    Institute of Scientific and Technical Information of China (English)

    Li Xiyue; Deng Wanling; Huang Junkai

    2012-01-01

    A physical drain current model of polysilicon thin-film transistors based on the charge-sheet model,the density of trap states and surface potential is proposed.The model uses non-iterative calculations,which are single-piece and valid in all operation regions above flat-band voltage.The distribution of the trap states,including both Gaussian deep-level states and exponential band-tail states,is also taken into account,and parameter extraction of trap state distribution is developed by the optoelectronic modulation spectroscopy measurement method.Comparisons with the available experimental data are accomplished,and good agreements are obtained.

  10. Progress in Thin Film Solar Cells Based on Cu2ZnSnS4

    OpenAIRE

    Hongxia Wang

    2011-01-01

    The research in thin film solar cells has been dominated by light absorber materials based on CdTe and Cu(In,Ga)Se2 (CIGS) in the last several decades. The concerns of environment impact of cadmium and the limited availability of indium in those materials have driven the research towards developing new substitute light absorbers made from earth abundant, environment benign materials. Cu2ZnSnS4 (CZTS) semiconductor material has emerged as one of the most promising candidates for this aim and h...

  11. Plasma monitoring and PECVD process control in thin film silicon-based solar cell manufacturing

    Directory of Open Access Journals (Sweden)

    Gabriel Onno

    2014-02-01

    Full Text Available A key process in thin film silicon-based solar cell manufacturing is plasma enhanced chemical vapor deposition (PECVD of the active layers. The deposition process can be monitored in situ by plasma diagnostics. Three types of complementary diagnostics, namely optical emission spectroscopy, mass spectrometry and non-linear extended electron dynamics are applied to an industrial-type PECVD reactor. We investigated the influence of substrate and chamber wall temperature and chamber history on the PECVD process. The impact of chamber wall conditioning on the solar cell performance is demonstrated.

  12. Tensoresistive Properties of Thin Film Systems Based on Ag and Co

    Directory of Open Access Journals (Sweden)

    I.M. Pazukha

    2012-10-01

    Full Text Available The results of research strain deformation properties of thin films Ag, Co and two-layers films Ag/Co in the range of deformation Δεl = 0-1 % were presented. The plastic deformation in Co layer caused a similar deformation in the entire film system, even if the strain range Ag layer is not reached the limits of the transition elastic/plastic deformation. The increasing of gauge factor value of two-layer systems in comparison with thin films Ag and Co appears as a result of electron interface scattering.

  13. Highly flexible transparent thin film heaters based on silver nanowires and aluminum zinc oxides

    Energy Technology Data Exchange (ETDEWEB)

    Cheong, Hahn-Gil; Kim, Jin-Hoon; Song, Jun-Hyuk; Jeong, Unyong; Park, Jin-Woo, E-mail: jwpark09@yonsei.ac.kr

    2015-08-31

    In this work, we developed highly flexible transparent film heaters (f-TFHs) composed of Ag nanowire networks (AgNWs) and aluminum zinc oxide (AZO). Uniform AgNWs were roll-to-roll coated on polyethylene terephthalate (PET) substrates using the Mayer rod method, and AZO was sputter-deposited atop the AgNWs at room temperature. The sheet resistance (R{sub s}) and transparency (T{sub opt}) of the AZO-coated AgNWs changed only slightly compared with the uncoated AgNWs. AZO is thermally less conductive than the heat pipes, but increases the thermal efficiency of the heaters blocking the heat convection through the air. Based on Joule heating, a higher average film temperature (T{sub ave}) is attained at a fixed electric potential drop between electrodes (ϕ) as the R{sub s} of the film decreases. Our experimental results revealed that T{sub ave} of the hybrid f-TFH is higher than AgNWs when the ratio of the area coverage of AgNWs to AZO is over a certain value. When a ϕ as low as 3 V/cm was applied to 5 cm × 5 cm f-TFHs, the maximum temperature of the hybrid film was over 100 °C, which is greater than that of AgNWs by more than 30 °C. Furthermore, uniform heating throughout the surfaces is achieved in the hybrid films while heating begins in small areas where densities of the nanowires (NWs) are the highest in the bare network. The non-uniform heating decreases the lifetime of f-TFHs by forming hot spots. Cyclic bending test results indicated that the hybrid films were as flexible as the AgNWs, and the R{sub s} of the hybrid films changes only slightly until 5000 cycles. Combined with the high-throughput coating technology presented here, the hybrid films will provide a robust and scalable strategy for large-area f-TFHs with highly enhanced performance. - Highlights: • We developed highly efficient flexible thin film heaters based on Ag nanowires and AZO composites. • In the composite, AZO plays an important role as an insulation blanket to block heat loss to

  14. Hall current sensor IC with integrated Co-based alloy thin film magnetic concentrator

    Science.gov (United States)

    Palumbo, V.; Marchesi, M.; Chiesi, V.; Paci, D.; Iuliano, P.; Toia, F.; Casoli, F.; Ranzieri, P.; Albertini, F.; Morelli, M.

    2013-01-01

    This work deals with a cobalt-based alloy thin film magnetic concentrator (MC) which is fully integrated on a Hall sensor integrated circuit (IC) developed in the 0.35 µm Bipolar CMOS DMOS (BCD) technology on 8" silicon wafer. An amorphous magnetic film with a thickness of 1µm, coercitive field Hc<10A/m and saturation magnetization (µ0MS) of 0.45T has been obtained with a sputtering process. The Hall sensor IC has shown sensitivity to magnetic field at room temperature of 240V/AT without concentrator and 2550V/AT with concentrator, gaining a factor of 10.5. A current sensor demonstrator has been realized showing linear response in the range -50 to 50A.

  15. Hall current sensor IC with integrated Co-based alloy thin film magnetic concentrator

    Directory of Open Access Journals (Sweden)

    Albertini F.

    2013-01-01

    Full Text Available This work deals with a cobalt-based alloy thin film magnetic concentrator (MC which is fully integrated on a Hall sensor integrated circuit (IC developed in the 0.35 µm Bipolar CMOS DMOS (BCD technology on 8” silicon wafer. An amorphous magnetic film with a thickness of 1µm, coercitive field Hc<10A/m and saturation magnetization (µ0MS of 0.45T has been obtained with a sputtering process. The Hall sensor IC has shown sensitivity to magnetic field at room temperature of 240V/AT without concentrator and 2550V/AT with concentrator, gaining a factor of 10.5. A current sensor demonstrator has been realized showing linear response in the range -50 to 50A.

  16. Polycrystalline thin film photovoltaic technology

    Energy Technology Data Exchange (ETDEWEB)

    Ullal, H.S.; Zweibel, K.; Mitchell, R.L.; Noufi, R.

    1991-03-01

    Low-cost, high-efficiency thin-film modules are an exciting photovoltaic technology option for generating cost-effective electricity in 1995 and beyond. In this paper we review the significant technical progress made in the following thin films: copper indium diselenide, cadmium telluride, and polycrystalline thin silicon films. Also, the recent US DOE/SERI initiative to commercialize these emerging technologies is discussed. 6 refs., 9 figs.

  17. Humidity Sensor Based on Multi-Walled Carbon Nanotube Thin Films

    OpenAIRE

    Cao, C. L.; Hu, C. G.; Fang, L.; Wang, S. X.; Y. S. TIAN; Pan, C. Y.

    2011-01-01

    The properties of the humidity sensors made of chemically treated and untreated multi-walled carbon nanotube (MWCNT) thin films are investigated systematically. It shows that both the chemically treated and untreated MWCNT thin films demonstrate humidity sensitive properties, but the former have stronger sensitivity than the latter. In the range of 11%–98% relative humidity (RH), the resistances of the chemically treated and untreated MWCNT humidity sensors increase 120% and 28%, respectively...

  18. ALD/MLD processes for Mn and Co based hybrid thin films.

    Science.gov (United States)

    Ahvenniemi, E; Karppinen, M

    2016-06-28

    Here we report the growth of novel transition metal-organic thin-film materials consisting of manganese or cobalt as the metal component and terephthalate as the rigid organic backbone. The hybrid thin films are deposited by the currently strongly emerging atomic/molecular layer deposition (ALD/MLD) technique using the combination of a metal β-diketonate, i.e. Mn(thd)3, Co(acac)3 or Co(thd)2, and terephthalic acid (1,4-benzenedicarboxylic acid) as precursors. All the processes yield homogeneous and notably smooth amorphous metal-terephthalate hybrid thin films with growth rates of 1-2 Å per cycle. The films are stable towards humidity and withstand high temperatures up to 300 or 400 °C under an oxidative or a reductive atmosphere. The films are characterized with XRR, AFM, GIXRD, XPS and FTIR techniques. PMID:27277668

  19. Adjustable grazing incidence x-ray optics based on thin PZT films

    Science.gov (United States)

    Cotroneo, Vincenzo; Davis, William N.; Marquez, Vanessa; Reid, Paul B.; Schwartz, Daniel A.; Johnson-Wilke, Raegan L.; Trolier-McKinstry, Susan E.; Wilke, Rudeger H. T.

    2012-10-01

    The direct deposition of piezoelectric thin films on thin substrates offers an appealing technology for the realization of lightweight adjustable mirrors capable of sub-arcsecond resolution. This solution will make it possible to realize X-ray telescopes with both large effective area and exceptional angular resolution and, in particular, it will enable the realization of the adjustable optics for the proposed mission Square Meter Arcsecond Resolution X-ray Telescope (SMART-X). In the past years we demonstrated for the first time the possibility of depositing a working piezoelectric thin film (1-5 um) made of lead-zirconate-titanate (PZT) on glass. Here we review the recent progress in film deposition and influence function characterization and comparison with finite element models. The suitability of the deposited films is analyzed and some constrains on the piezoelectric film performances are derived. The future steps in the development of the technology are described.

  20. Aspects of passive magnetic levitation based on high-T(sub c) superconducting YBCO thin films

    Science.gov (United States)

    Schoenhuber, P.; Moon, F. C.

    1995-04-01

    Passive magnetic levitation systems reported in the past were mostly confined to bulk superconducting materials. Here we present fundamental studies on magnetic levitation employing cylindrical permanent magnets floating above high-T(sub c) superconducting YBCO thin films (thickness about 0.3 mu m). Experiments included free floating rotating magnets as well as well-established flexible beam methods. By means of the latter, we investigated levitation and drag force hysteresis as well as magnetic stiffness properties of the superconductor-magnet arrangement. In the case of vertical motion of the magnet, characteristic high symmetry of repulsive (approaching) and attractive (withdrawing) branches of the pronounced force-displacement hysteresis could be detected. Achievable force levels were low as expected but sufficient for levitation of permanent magnets. With regard to magnetic stiffness, thin films proved to show stiffness-force ratios about one order of magnitude higher than bulk materials. Phenomenological models support the measurements. Regarding the magnetic hysteresis of the superconductor, the Irie-Yamafuji model was used for solving the equation of force balance in cylindrical coordinates allowing for a macroscopic description of the superconductor magnetization. This procedure provided good agreement with experimental levitation force and stiffness data during vertical motion. For the case of (lateral) drag force basic qualitative characteristics could be recovered, too. It is shown that models, based on simple asymmetric magnetization of the superconductor, describe well asymptotic transition of drag forces after the change of the magnet motion direction. Virgin curves (starting from equilibrium, i.e. symmetric magnetization) are approximated by a linear approach already reported in literature only. This paper shows that basic properties of superconducting thin films allow for their application to magnetic levitation or - without need of levitation

  1. Aspects of passive magnetic levitation based on high-T(sub c) superconducting YBCO thin films

    Science.gov (United States)

    Schoenhuber, P.; Moon, F. C.

    1995-01-01

    Passive magnetic levitation systems reported in the past were mostly confined to bulk superconducting materials. Here we present fundamental studies on magnetic levitation employing cylindrical permanent magnets floating above high-T(sub c) superconducting YBCO thin films (thickness about 0.3 mu m). Experiments included free floating rotating magnets as well as well-established flexible beam methods. By means of the latter, we investigated levitation and drag force hysteresis as well as magnetic stiffness properties of the superconductor-magnet arrangement. In the case of vertical motion of the magnet, characteristic high symmetry of repulsive (approaching) and attractive (withdrawing) branches of the pronounced force-displacement hysteresis could be detected. Achievable force levels were low as expected but sufficient for levitation of permanent magnets. With regard to magnetic stiffness, thin films proved to show stiffness-force ratios about one order of magnitude higher than bulk materials. Phenomenological models support the measurements. Regarding the magnetic hysteresis of the superconductor, the Irie-Yamafuji model was used for solving the equation of force balance in cylindrical coordinates allowing for a macroscopic description of the superconductor magnetization. This procedure provided good agreement with experimental levitation force and stiffness data during vertical motion. For the case of (lateral) drag force basic qualitative characteristics could be recovered, too. It is shown that models, based on simple asymmetric magnetization of the superconductor, describe well asymptotic transition of drag forces after the change of the magnet motion direction. Virgin curves (starting from equilibrium, i.e. symmetric magnetization) are approximated by a linear approach already reported in literature only. This paper shows that basic properties of superconducting thin films allow for their application to magnetic levitation or - without need of levitation

  2. Inkjet-based deposition of polymer thin films enabled by a lubrication model incorporating nano-scale parasitics

    Science.gov (United States)

    Singhal, Shrawan; Meissl, Mario J.; Bonnecaze, Roger T.; Sreenivasan, S. V.

    2013-09-01

    Thin film lubrication theory has been widely used to model multi-scale fluid phenomena. Variations of the same have also found application in fluid-based manufacturing process steps for micro- and nano-scale devices over large areas where a natural disparity in length scales exists. Here, a novel inkjet material deposition approach has been enabled by an enhanced thin film lubrication theory that accounts for nano-scale substrate parasitics. This approach includes fluid interactions with a thin flexible superstrate towards a new process called Jet and Coat of Thin-films (JCT). Numerical solutions of the model have been verified, and also validated against controlled experiments of polymer film deposition with good agreement. Understanding gleaned from the experimentally validated model has then been used to facilitate JCT process synthesis resulting in substantial reduction in the influence of parasitics and a concomitant improvement in the film thickness uniformity. Polymer films ranging from 20 to 500 nm mean thickness have been demonstrated with standard deviation of less than 2% of the mean film thickness. The JCT process offers advantages over spin coating which is not compatible with roll-to-roll processing and large area processing for displays. It also improves over techniques such as knife edge coating, slot die coating, as they are limited in the range of thicknesses of films that can be deposited without compromising uniformity.

  3. Investigation on Silicon Thin Film Solar Cells

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The preparation, current status and trends are investigated for silicon thin film solar cells. The advantages and disadvantages of amorphous silicon thin film, polycrystalline silicon thin film and mono-crystalline silicon thin film solar cells are compared. The future development trends are pointed out. It is found that polycrystalline silicon thin film solar cells will be more promising for application with great potential.

  4. High energy oxygen ion induced modifications in lead based perovskite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Jali, V.M. [Department of Physics, Gulbarga University, Gulbarga - 585 106 (India)]. E-mail: vmjali@rediffmail.com; Angadi, Basavaraj [Thin Films Materials Research Center, Korea Institute of Science and Technology, Seoul 130-650 (Korea, Republic of); Venkateswarlu, P. [Solar Panels Division, ISRO Satellite Centre, Bangalore - 560 017 (India); Kumar, Ravi [Materials Science Division, Inter University Accelerator Center, New-Delhi - 110 067 (India); Krupanidhi, S.B. [Materials Research Centre, Indian Institute of Science, Bangalore - 560 012 (India)

    2007-07-15

    The lead based ferroelectric PbZr{sub 0.53}Ti{sub 0.47}O{sub 3} (PZT), (Pb{sub 0.90}La{sub 0.10})TiO{sub 3} (PLT10) and (Pb{sub 0.80}La{sub 0.20})TiO{sub 3} (PLT20) thin films, prepared by pulsed laser ablation technique, were studied for their response to the 70 MeV oxygen ion irradiation. The dielectric analysis, capacitance-voltage (C-V) and DC leakage current measurements were performed before and after the irradiation to high-energy oxygen ions. The irradiation produced considerable changes in the dielectric, C-V, leakage characteristics and induced some amount of amorphization. The PZT films showed partial recrystallization after a thermal annealing at 400 deg. C for 10 min. The phase transition temperature [T {sub c}] of PLT20 increased from 115 deg. C to 120 deg. C. The DC conductivity measurements showed a shift in the onset of non-linear conduction region. The current density decreased by two orders of magnitude after irradiation. After annealing the irradiated films at a temperature of 400 deg. C for 10 min, the films partially regained the dielectric and electrical properties. The results are discussed in terms of the irradiation-induced amorphization, the pinning of the ferroelectric domains by trapped charges and the thermal annealing of the defects generated during the irradiation.

  5. Superconducting detector of IR single-photons based on thin WSi films

    Science.gov (United States)

    Seleznev, V. A.; Divochiy, A. V.; Vakhtomin, Yu B.; Morozov, P. V.; Zolotov, P. I.; Vasil'ev, D. D.; Moiseev, K. M.; Malevannaya, E. I.; Smirnov, K. V.

    2016-08-01

    We have developed the deposition technology of WSi thin films 4 to 9 nm thick with high temperature values of superconducting transition (Tc~4 K). Based on deposed films there were produced nanostructures with indicative planar sizes ~100 nm, and the research revealed that even on nanoscale the films possess of high critical temperature values of the superconducting transition (Tc~3.3-3.7 K) which certifies high quality and homogeneity of the films created. The first experiments on creating superconducting single-photon detectors showed that the detectors’ SDE (system detection efficiency) with increasing bias current (I b) reaches a constant value of ~30% (for X=1.55 micron) defined by infrared radiation absorption by the superconducting structure. To enhance radiation absorption by the superconductor there were created detectors with cavity structures which demonstrated a practically constant value of quantum efficiency >65% for bias currents Ib>0.6-Ic. The minimal dark counts level (DC) made 1 s-1 limited with background noise. Hence WSi is the most promising material for creating single-photon detectors with record SDE/DC ratio and noise equivalent power (NEP).

  6. Robust thin-film generator based on segmented contact-electrification for harvesting wind energy.

    Science.gov (United States)

    Meng, Xian Song; Zhu, Guang; Wang, Zhong Lin

    2014-06-11

    Collecting and converting energy from ambient air flow promise to be a viable approach in developing self-powered autonomous electronics. Here, we report an effective and robust triboelectric generator that consists of an undulating thin-film membrane and an array of segmented fine-sized electrode pairs on a single substrate. Sequential processes of contact electrification and electrostatic induction generate alternating flows of free electrons when the membrane interacts with ambient air flow. Based on an optimum rational design, the segmented electrodes play an essential role in boosting the output current, leading to an enhancement of over 500% compared to the structure without the segmentation. The thin-film based generator can simultaneously and continuously light up tens of commercial light-emitting diodes. Moreover, it possesses exceptional durability, providing constant electric output after millions of operation cycles. This work offers a truly practical solution that opens the avenue to take advantage of wind energy by using the triboelectric effect. PMID:24824071

  7. n +-Microcrystalline-Silicon Tunnel Layer in Tandem Si-Based Thin Film Solar Cells

    Science.gov (United States)

    Lee, Ching-Ting; Lee, Hsin-Ying; Chen, Kuan-Hao

    2016-06-01

    In this study, the p-SiC/i-Si/n-Si cell and the p-SiC/i-SiGe/n-Si cell deposited using plasma-enhanced chemical vapor deposition were cascaded for forming the tandem Si-based thin film solar cells to absorb the wide solar spectrum. To further improve the performances of the tandem Si-based thin film solar cells, a 5-nm-thick n +-microcrystalline-Si (n +-μc-Si) tunnel layer deposited using the laser-assisted plasma-enhanced chemical vapor deposition was inserted between the p-SiC/i-Si/n-Si cell and the p-SiC/i-SiGe/n-Si cell. Since both the plasma and the CO2 laser were simultaneously utilized to efficiently decompose the reactant and doping gases, the carrier concentration and the carrier mobility of the n +-μc-Si tunnel layer were significantly improved. The ohmic contact formed between the p-SiC layer and the n +-μc-Si tunnel layer with low resistance was beneficial to the generated current transportation and the carrier recombination rate. Therefore, the conversion efficiency of the tandem solar cells was promoted from 8.57% and 8.82% to 9.91% compared to that without tunnel layer and with 5-nm-thick n +-amorphous-Si tunnel layer.

  8. n +-Microcrystalline-Silicon Tunnel Layer in Tandem Si-Based Thin Film Solar Cells

    Science.gov (United States)

    Lee, Ching-Ting; Lee, Hsin-Ying; Chen, Kuan-Hao

    2016-10-01

    In this study, the p-SiC/ i-Si/ n-Si cell and the p-SiC/ i-SiGe/ n-Si cell deposited using plasma-enhanced chemical vapor deposition were cascaded for forming the tandem Si-based thin film solar cells to absorb the wide solar spectrum. To further improve the performances of the tandem Si-based thin film solar cells, a 5-nm-thick n +-microcrystalline-Si ( n +-μc-Si) tunnel layer deposited using the laser-assisted plasma-enhanced chemical vapor deposition was inserted between the p-SiC/ i-Si/ n-Si cell and the p-SiC/ i-SiGe/ n-Si cell. Since both the plasma and the CO2 laser were simultaneously utilized to efficiently decompose the reactant and doping gases, the carrier concentration and the carrier mobility of the n +-μc-Si tunnel layer were significantly improved. The ohmic contact formed between the p-SiC layer and the n +-μc-Si tunnel layer with low resistance was beneficial to the generated current transportation and the carrier recombination rate. Therefore, the conversion efficiency of the tandem solar cells was promoted from 8.57% and 8.82% to 9.91% compared to that without tunnel layer and with 5-nm-thick n +-amorphous-Si tunnel layer.

  9. Anomalous Hall effect sensors based on magnetic element doped topological insulator thin films

    Science.gov (United States)

    Ni, Yan; Zhang, Zhen; Nlebedim, Ikenna; Jiles, David

    Anomalous Hall effect (AHE) is recently discovered in magnetic element doped topological insulators (TIs), which promises low power consumption highly efficient spintronics and electronics. This discovery broaden the family of Hall effect (HE) sensors. In this work, both HE and AHE sensor based on Mn and Cr doped Bi2Te3 TI thin films will be systematically studied. The influence of Mn concentration on sensitivity of MnxBi2-xTe3 HE sensors will be discussed. The Hall sensitivity increase 8 times caused by quantum AHE will be reported. AHE senor based on Cr-doped Bi2Te3 TI thin films will also be studied and compared with Mn doped Bi2Te3 AHE sensor. The influence of thickness on sensitivity of CrxBi2-xTe3 AHE sensors will be discussed. Ultrahigh Hall sensitivity is obtained in Cr doped Bi2Te3. The largest Hall sensitivity can reach 2620 Ω/T in sensor which is almost twice higher than that of the normal semiconductor HE sensor. Our work indicates that magnetic element doped topological insulator with AHE are good candidates for ultra-sensitive Hall effect sensors.

  10. Basella alba rubra spinach pigment-sensitized TiO2 thin film-based solar cells

    Science.gov (United States)

    Gokilamani, N.; Muthukumarasamy, N.; Thambidurai, M.; Ranjitha, A.; Velauthapillai, Dhayalan

    2015-03-01

    Nanocrystalline TiO2 thin films have been prepared by sol-gel dip coating method. The X-ray diffraction results showed that TiO2 thin films annealed at 400, 450 and 500 °C are of anatase phase and the peak corresponding to the (101) plane is present in all the samples. The grain size of TiO2 thin films was found to increase with increasing annealing temperature. The grain size is found to be 20, 25 and 33 nm for the films annealed at 400, 450 and 500 °C. The structure of the TiO2 nanocrystalline thin films have been examined by high-resolution transmission electron microscope, Raman spectroscopy and FTIR spectroscopy. TiO2 thin films were sensitized by natural dyes extracted from basella alba rubra spinach. It was found that the absorption peak of basella alba rubra extract is at about 665 nm. The dye-sensitized TiO2-based solar cell sensitized using basella alba rubra exhibited a J sc of 4.35 mA cm-2, V oc of 0.48 V, FF of 0.35 and efficiency of 0.70 %. Natural dyes as sensitizers for dye-sensitized solar cells are promising because of their environmental friendliness, low-cost production and fully biodegradable.

  11. Fabrication of Thermoelectric Sensor and Cooling Devices Based on Elaborated Bismuth-Telluride Alloy Thin Films

    Directory of Open Access Journals (Sweden)

    Abdellah Boulouz

    2014-01-01

    Full Text Available The principal motivation of this work is the development and realization of smart cooling and sensors devices based on the elaborated and characterized semiconducting thermoelectric thin film materials. For the first time, the details design of our sensor and the principal results are published. Fabrication and characterization of Bi/Sb/Te (BST semiconducting thin films have been successfully investigated. The best values of Seebeck coefficient (α(T at room temperature for Bi2Te3, and (Bi1−xSbx2Te3 with x = 0.77 are found to be −220 µV/K and +240 µV/K, respectively. Fabrication and evaluation of performance devices are reported. 2.60°C of cooling of only one Peltier module device for an optimal current of Iopt=2.50 mA is obtained. The values of temperature measured by infrared camera, by simulation, and those measured by the integrated and external thermocouple are reported. A sensitivity of the sensors of 5 mV Torr−1 mW−1 for the pressure sensor has been found with a response time of about 600 ms.

  12. Solution-based synthesis of cobalt-doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Vempati, Sesha [School of Mathematics and Physics, Queen' s University Belfast, BT7 1NN (United Kingdom); Shetty, Amitha [Materials Research Center, Indian Institute of Science, Bangalore 560012 (India); Dawson, P., E-mail: p.dawson@qub.ac.uk [School of Mathematics and Physics, Queen' s University Belfast, BT7 1NN (United Kingdom); Nanda, K.K.; Krupanidhi, S.B. [Materials Research Center, Indian Institute of Science, Bangalore 560012 (India)

    2012-12-01

    Undoped and cobalt-doped (1-4 wt.%) ZnO polycrystalline, thin films have been fabricated on quartz substrates using sequential spin-casting and annealing of simple salt solutions. X-ray diffraction (XRD) reveals a wurzite ZnO crystalline structure with high-resolution transmission electron microscopy showing lattice planes of separation 0.26 nm, characteristic of (002) planes. The Co appears to be tetrahedrally co-ordinated in the lattice on the Zn sites (XRD) and has a charge of + 2 in a high-spin electronic state (X-ray photoelectron spectroscopy). Co-doping does not alter the wurzite structure and there is no evidence of the precipitation of cobalt oxide phases within the limits of detection of Raman and XRD analysis. Lattice defects and chemisorbed oxygen are probed using photoluminescence and Raman spectroscopy - crucially, however, this transparent semiconductor material retains a bandgap in the ultraviolet (3.30-3.48 eV) and high transparency (throughout the visible spectral regime) across the doping range. - Highlights: Black-Right-Pointing-Pointer Simple solution-based method for the fabrication of Co-doped ZnO thin films. Black-Right-Pointing-Pointer Evidence for Co substitution on Zn sites in + 2 oxidation state. Black-Right-Pointing-Pointer ZnO, with up to 4% Co doping, retains high transparency across visible spectrum. Black-Right-Pointing-Pointer Quenching of exciton photoluminescence linked to chemisorbed oxygen in Co-doped ZnO.

  13. Superlattice-based thin-film thermoelectric modules with high cooling fluxes

    Science.gov (United States)

    Bulman, Gary; Barletta, Phil; Lewis, Jay; Baldasaro, Nicholas; Manno, Michael; Bar-Cohen, Avram; Yang, Bao

    2016-01-01

    In present-day high-performance electronic components, the generated heat loads result in unacceptably high junction temperatures and reduced component lifetimes. Thermoelectric modules can, in principle, enhance heat removal and reduce the temperatures of such electronic devices. However, state-of-the-art bulk thermoelectric modules have a maximum cooling flux qmax of only about 10 W cm-2, while state-of-the art commercial thin-film modules have a qmax management of modern high-power devices. Here we show that cooling fluxes of 258 W cm-2 can be achieved in thin-film Bi2Te3-based superlattice thermoelectric modules. These devices utilize a p-type Sb2Te3/Bi2Te3 superlattice and n-type δ-doped Bi2Te3-xSex, both of which are grown heteroepitaxially using metalorganic chemical vapour deposition. We anticipate that the demonstration of these high-cooling-flux modules will have far-reaching impacts in diverse applications, such as advanced computer processors, radio-frequency power devices, quantum cascade lasers and DNA micro-arrays.

  14. Voltage controlled exchange bias in an all-thin-film Cr2O3 based heterostructure

    Science.gov (United States)

    Echtenkamp, Will; Binek, Christian

    2014-03-01

    Spintronics utilizes the electron's spin degree of freedom for an advanced generation of electronic devices with novel functionalities. Controlling magnetism by electrical means has been identified as a key challenge in the field of spintronics, and electric control of exchange bias is one of the most promising routes to address this challenge. Previously, robust isothermal electric control of exchange bias has been achieved near room temperature utilizing a bulk single crystal of Cr2O3. In this study electric control of exchange bias in an all-thin-film system is demonstrated with significant implications for device realization. In particular, voltage controlled switching of exchange bias in a Cr2O3 based magnetoelectric magnetic tunnel junction enables nonvolatile memory storage with virtually dissipationless writing at, or above, room temperature. Additionally, unique physical properties which arise due to the Cr2O3 thin film geometry are highlighted. This project is supported by NSF through MRSEC DMR 0213808, by the NRC/NRI supplement to MRSEC, and by CNFD and C-SPIN, one of six centers of STARnet, a Semiconductor Research Corporation program.

  15. Anisotropic ferromagnetic behaviors in highly orientated epitaxial NiO-based thin films

    Directory of Open Access Journals (Sweden)

    Yu-Jun Zhang

    2015-07-01

    Full Text Available Antiferromagnetic materials attract a great amount of attention recently for promising antiferromagnet-based spintronics applications. NiO is a conventional antiferromagnetic semiconductor material and can show ferromagnetism by doping other magnetic elements. In this work, we synthesized epitaxial Fe-doped NiO thin films on SrTiO3 substrates with various crystal orientations by pulsed laser deposition. The room-temperature ferromagnetism of these films is anisotropic, including the saturated magnetization and the coercive field. The anisotropic magnetic behaviors of Fe-doped NiO diluted magnetic oxide system should be closely correlated to the magnetic structure of antiferromagnetic NiO base. Within the easy plane of NiO, the coercive field of the films becomes smaller, and larger coercive field while tested out of the easy plane of NiO. The saturated magnetization anisotropy is due to different strain applied by different substrates. These results lead us to more abundant knowledge of the exchange interactions in this conventional antiferromagnetic system.

  16. Novel applications of piezoresistive thin film systems based on hydrogenated carbon

    Science.gov (United States)

    Biehl, Saskia; Rumposch, Christian; Recknagel, Christian

    2013-05-01

    Thin film sensor systems based on hydrogenated carbon have the advantage to combine two very important characteristics. They show a piezoresistive behaviour and also a tribological stability caused by a high hardness and wear resistance. Therefore they can be applied on the surface of machine parts or used for building up universal insertable sensor systems like sensory washers. A real challenge is the deposition of a whole sensory layer system on technical components like a spindle, which have a length of 480 mm and an outer diameter of about 90 mm. The functions of the layer system directly applied in the contact zone between spindle shaft and tool holder are the measurement of the clamping force of the tool holder, the imbalance of the used tool and the process forces during machining. For this application a self-contained thin film sensor system is investigated. Directly in the spindle shaft an insulating alumina layer is deposited in a thickness of about 4 μm followed by electrode structures out of 200 nm thin chromium coating. On top of this the piezoresistive hydrogenated carbon layer in a thickness of about 1 μm is deposited, covered by a wear resistant and insulating top coating. Therefore a silicon and oxygen modified carbon layer in a thickness of about 2 μm is used. The piezoresistive sensor layer and also the top layer are part of the diamond like carbon layer family [1,2,3,4]. Another very important application is the sensory washer. The thin film sensor system, consisting out of the piezoresistive sensor layer deposited directly on the washer surface, the electrode structures out of chromium for the local detection of the load distribution in the washer system and the insulating layer as top layer out of the silicon and oxygen modified carbon layer, has a thickness in the range of 9 μm. In the latest investigations this layer system is connected with a RFID-chip for contactless data transmission.

  17. Low loss spin wave resonances in organic-based ferrimagnet vanadium tetracyanoethylene thin films

    Science.gov (United States)

    Zhu, Na; Zhang, Xufeng; Froning, I. H.; Flatté, Michael E.; Johnston-Halperin, E.; Tang, Hong X.

    2016-08-01

    We experimentally demonstrate high quality factor spin wave resonances in an encapsulated thin film of the organic-based ferrimagnet vanadium tetracyanoethylene ( V [TC N E ] x ˜2 ) coated on an a-plane sapphire substrate by low temperature chemical vapor deposition. The thickness standing wave modes are observed in a broad frequency range (1 GHz-5 GHz) with high quality factor exceeding 3200 in ambient air at room temperature, rivaling those of inorganic magnetic materials. The exchange constant of V [TC N E ] x ˜2 , a crucial material parameter for future study and device design of the V [TC N E ] x ˜2 , is extracted from the measurement with a value of (4.61 ±0.35 ) ×10-16 m2 . Our result establishes the feasibility of using organic-based materials for building hybrid magnonic devices and circuits.

  18. Controllable film densification and interface flatness for high-performance amorphous indium oxide based thin film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Ou-Yang, Wei, E-mail: OUYANG.Wei@nims.go.jp, E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Mitoma, Nobuhiko; Kizu, Takio; Gao, Xu; Lin, Meng-Fang; Tsukagoshi, Kazuhito, E-mail: OUYANG.Wei@nims.go.jp, E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp [International Center for Materials Nanoarchitectronics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Nabatame, Toshihide [MANA Foundry and MANA Advanced Device Materials Group, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

    2014-10-20

    To avoid the problem of air sensitive and wet-etched Zn and/or Ga contained amorphous oxide transistors, we propose an alternative amorphous semiconductor of indium silicon tungsten oxide as the channel material for thin film transistors. In this study, we employ the material to reveal the relation between the active thin film and the transistor performance with aid of x-ray reflectivity study. By adjusting the pre-annealing temperature, we find that the film densification and interface flatness between the film and gate insulator are crucial for achieving controllable high-performance transistors. The material and findings in the study are believed helpful for realizing controllable high-performance stable transistors.

  19. Developing high-transmittance heterojunction diodes based on NiO/TZO bilayer thin films.

    Science.gov (United States)

    Huang, Chia-Cheng; Wang, Fang-Hsing; Wu, Chia-Ching; Huang, Hong-Hsin; Yang, Cheng-Fu

    2013-01-01

    In this study, radio frequency magnetron sputtering was used to deposit nickel oxide thin films (NiO, deposition power of 100 W) and titanium-doped zinc oxide thin films (TZO, varying deposition powers) on glass substrates to form p(NiO)-n(TZO) heterojunction diodes with high transmittance. The structural, optical, and electrical properties of the TZO and NiO thin films and NiO/TZO heterojunction devices were investigated with scanning electron microscopy, X-ray diffraction (XRD) patterns, UV-visible spectroscopy, Hall effect analysis, and current-voltage (I-V) analysis. XRD analysis showed that only the (111) diffraction peak of NiO and the (002) and (004) diffraction peaks of TZO were observable in the NiO/TZO heterojunction devices, indicating that the TZO thin films showed a good c-axis orientation perpendicular to the glass substrates. When the sputtering deposition power for the TZO thin films was 100, 125, and 150 W, the I-V characteristics confirmed that a p-n junction characteristic was successfully formed in the NiO/TZO heterojunction devices. We show that the NiO/TZO heterojunction diode was dominated by the space-charge limited current theory.

  20. Indium oxide thin film based ammonia gas and ethanol vapour sensor

    Indian Academy of Sciences (India)

    K K Makhija; Arabinda Ray; R M Patel; U B Trivedi; H N Kapse

    2005-02-01

    A sensor for ammonia gas and ethanol vapour has been fabricated using indium oxide thin film as sensing layer and indium tin oxide thin film encapsulated in poly(methyl methacrylate) (PMMA) as a miniature heater. For the fabrication of miniature heater indium tin oxide thin film was grown on special high temperature corning glass substrate by flash evaporation method. Gold was deposited on the film using thermal evaporation technique under high vacuum. The film was then annealed at 700 K for an hour. The thermocouple attached on sensing surface measures the appropriate operating temperature. The thin film gas sensor for ammonia was operated at different concentrations in the temperature range 323–493 K. At 473 K the sensitivity of the sensor was found to be saturate. The detrimental effect of humidity on ammonia sensing is removed by intermittent periodic heating of the sensor at the two temperatures 323K and 448 K, respectively. The indium oxide ethanol vapour sensor operated at fixed concentration of 400 ppm in the temperature range 293–393 K. Above 373 K, the sensor conductance was found to be saturate. With various thicknesses from 150–300 nm of indium oxide sensor there was no variation in the sensitivity measurements of ethanol vapour. The block diagram of circuits for detecting the ammonia gas and ethanol vapour has been included in this paper.

  1. Adsorption properties of Mg-Al layered double hydroxides thin films grown by laser based techniques

    Energy Technology Data Exchange (ETDEWEB)

    Matei, A., E-mail: andreeapurice@nipne.ro [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest, Magurele (Romania); Birjega, R.; Vlad, A.; Filipescu, M.; Nedelcea, A.; Luculescu, C. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest, Magurele (Romania); Zavoianu, R.; Pavel, O.D. [University of Bucharest, Faculty of Chemistry, Department of Chemical Technology and Catalysis, 4-12 Regina Elisabeta Bd., Bucharest (Romania); Dinescu, M. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest, Magurele (Romania)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer Laser techniques MAPLE and PLD can successfully be used to produce LDHs thin films. Black-Right-Pointing-Pointer Hydration treatments of the PLD and MAPLE deposited films lead to the LDH reconstruction effect. Black-Right-Pointing-Pointer The Ni retention from aqueous solution occurs in the films via a dissolution-reconstruction mechanism. Black-Right-Pointing-Pointer The films are suitable for applications in remediation of contaminated drinking water or waste waters. - Abstract: Powdered layered double hydroxides (LDHs) have been widely studied due to their applications as catalysts, anionic exchangers or host materials for inorganic and/or organic molecules. Assembling nano-sized LDHs onto flat solid substrates forming thin films is an expanding area of research due to the prospects of novel applications as sensors, corrosion-resistant coatings, components in optical and magnetic devices. Continuous and adherent thin films were grown by laser techniques (pulsed laser deposition - PLD and matrix assisted pulsed laser evaporation - MAPLE) starting from targets of Mg-Al LDHs. The capacity of the grown thin films to retain a metal (Ni) from contaminated water has been also explored. The thin films were immersed in an Ni(NO{sub 3}){sub 2} aqueous solutions with Ni concentrations of 10{sup -3}% (w/w) (1 g/L) and 10{sup -4}% (w/w) (0.1 g/L), respectively. X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) combined with energy dispersive X-ray analysis (EDX) were the techniques used to characterize the prepared materials.

  2. Organic solar cells based on liquid crystalline and polycrystalline thin films

    Science.gov (United States)

    Yoo, Seunghyup

    This dissertation describes the study of organic thin-film solar cells in pursuit of affordable, renewable, and environmentally-friendly energy sources. Particular emphasis is given to the molecular ordering found in liquid crystalline or polycrystalline films as a way to leverage the efficiencies of these types of cells. Maximum efficiencies estimated based on excitonic character of organic solar cells show power conversion efficiencies larger than 10% are possible in principle. However, their performance is often limited due to small exciton diffusion lengths and poor transport properties which may be attributed to the amorphous nature of most organic semiconductors. Discotic liquid crystal (DLC) copper phthalocyanine was investigated as an easily processible building block for solar cells in which ordered molecular arrangements are enabled by a self-organization in its mesophases. An increase in photocurrent and a reduction in series resistance have been observed in a cell which underwent an annealing process. X-ray diffraction (XRD) and atomic force microscopy (AFM) measurements suggest that structural and morphological changes induced after the annealing process are related to these improvements. In an alternative approach, p-type pentacene thin films prepared by physical vapor deposition were incorporated into heterojunction solar cells with C60 as n-type layers. Power conversion efficiencies of 2.7% under broadband illumination (350--900 nm) with a peak external quantum efficiency of 58% have been achieved with the broad spectral coverage across the visible spectrum. Analysis using an exciton diffusion model shows this efficient carrier generation is mainly due to the large exciton diffusion length of pentacene films. Joint XRD and AFM studies reveal that the highly crystalline nature of pentacene films can account for the observed large exciton diffusion length. In addition, the electrical characteristics are studied as a function of light intensity using

  3. Polycrystalline thin films

    Science.gov (United States)

    Zweibel, K.; Mitchell, R.; Ullal, H.

    1987-02-01

    This annual report for fiscal year 1986 summarizes the status, accomplishments, and projected future research directions of the Polycrystalline Thin Film Task in the Photovoltaic Program Branch of the Solar Energy Research Institute's Solar Electric Research Division. Subcontracted work in this area has concentrated on the development of CuInSe2 and CdTe technologies. During FY 1986, major progress was achieved by subcontractors in (1) achieving 10.5% (SERI-verified) efficiency with CdTe, (2) improving the efficiency of selenized CuInSe2 solar cells to nearly 8%, and (3) developing a transparent contact to CdTe cells for potential use in the top cells of tandem structures.

  4. Polyimide Aerogel Thin Films

    Science.gov (United States)

    Meador, Mary Ann; Guo, Haiquan

    2012-01-01

    Polyimide aerogels have been crosslinked through multifunctional amines. This invention builds on "Polyimide Aerogels With Three-Dimensional Cross-Linked Structure," and may be considered as a continuation of that invention, which results in a polyimide aerogel with a flexible, formable form. Gels formed from polyamic acid solutions, end-capped with anhydrides, and cross-linked with the multifunctional amines, are chemically imidized and dried using supercritical CO2 extraction to give aerogels having density around 0.1 to 0.3 g/cubic cm. The aerogels are 80 to 95% porous, and have high surface areas (200 to 600 sq m/g) and low thermal conductivity (as low as 14 mW/m-K at room temperature). Notably, the cross-linked polyimide aerogels have higher modulus than polymer-reinforced silica aerogels of similar density, and can be fabricated as both monoliths and thin films.

  5. Characteristic of TiNi(Cu) shape memory thin film based on micropump

    Science.gov (United States)

    Zhang, Huijun; Qiu, Chengjun

    2009-07-01

    Shape memory thin films offer a unique combination of novel properties and have the potential to become a primary actuating mechanism for micropumps. In this study, a micropump driven by TiNiCu shape memory thin film is designed and fabricated. The micropump is composed of a TiNiCu/Si bimorph driving membrane, a pump chamber and two inlet and outlet check valves. The property of TiNiCu films and driving capacity of TiNiCu/Si bimorph driving membrane are investigated. By using the recoverable force of TiNiCu thin film and biasing force of silicon membrane, the actuation diaphragm realizes reciprocating motion effectively. Experimental results show that the film surface appears a smooth and featureless morphology without any cracks, and the hysteresis width ΔT of TiNiCu film is about 2-3°C, the micropump driving by TiNiCu film has good performance, such as high pumping yield, high working frequency, stable driving capacity, and long fatigue life time.

  6. Low-voltage gallium-indium-zinc-oxide thin film transistors based logic circuits on thin plastic foil: Building blocks for radio frequency identification application

    NARCIS (Netherlands)

    Tripathi, A.K.; Smits, E.C.P.; Putten, J.B.P.H. van der; Neer, M. van; Myny, K.; Nag, M.; Steudel, S.; Vicca, P.; O'Neill, K.; Veenendaal, E. van; Genoe, G.; Heremans, P.; Gelinck, G.H.

    2011-01-01

    In this work a technology to fabricate low-voltage amorphous gallium-indium-zinc oxide thin film transistors (TFTs) based integrated circuits on 25 µm foils is presented. High performance TFTs were fabricated at low processing temperatures (<150 °C) with field effect mobility around 17 cm2 /V s. The

  7. Difference in the outdoor performance of bulk and thin-film silicon-based photovoltaic modules

    Energy Technology Data Exchange (ETDEWEB)

    Minemoto, Takashi; Fukushige, Shunichi; Takakura, Hideyuki [College of Science and Engineering, Ritsumeikan University1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577 (Japan)

    2009-06-15

    Differences in the outdoor performances of bulk (multi- and single-crystalline Si) and thin-film (amorphous Si(a-Si), a-Si/micro-crystalline Si and a-Si/a-SiGe/a-SiGe) photovoltaic (PV) modules are analyzed. The influence of module temperature and solar spectrum distribution on the PV output is clarified. The PV outputs almost only depend on module temperature in bulk-type Si PV modules while that depend both module temperature and spectrum distribution in thin-film ones. Also, the PV outputs of the bulk-type Si PV modules at most frequent condition at outdoor are lower than that at the standard test condition; in contrast, it was the other way round for thin-film ones. (author)

  8. Room-temperature fabrication of light-emitting thin films based on amorphous oxide semiconductor

    Directory of Open Access Journals (Sweden)

    Junghwan Kim

    2016-01-01

    Full Text Available We propose a light-emitting thin film using an amorphous oxide semiconductor (AOS because AOS has low defect density even fabricated at room temperature. Eu-doped amorphous In-Ga-Zn-O thin films fabricated at room temperature emitted intense red emission at 614 nm. It is achieved by precise control of oxygen pressure so as to suppress oxygen-deficiency/excess-related defects and free carriers. An electronic structure model is proposed, suggesting that non-radiative process is enhanced mainly by defects near the excited states. AOS would be a promising host for a thin film phosphor applicable to flexible displays as well as to light-emitting transistors.

  9. Cross-linked PAN-based thin-film composite membranes for non-aqueous nanofiltration

    KAUST Repository

    Pérez-Manríquez, Liliana

    2015-01-01

    A new approach on the development of cross-linked PAN based thin film composite (TFC) membranes for non-aqueous application is presented in this work. Polypropylene backed neat PAN membranes fabricated by phase inversion process were cross-linked with hydrazine to get excellent solvent stability toward dimethylformamide (DMF). By interfacial polymerization a selective polyamide active layer was coated over the cross-linked PAN using N,N′-diamino piperazine (DAP) and trimesoyl chloride (TMC) as monomers. Permeation and molecular weight cut off (MWCO) experiments using various dyes were done to evaluate the performance of the membranes. Membranes developed by such method show excellent solvent stability toward DMF with a permeance of 1.7 L/m2 h bar and a molecular weight cut-off of less than 600 Da.

  10. Low-voltage Driving Phototransistor Based on Dye-sensitized Nanocrystalline Titanium Dioxide Thin Films

    CERN Document Server

    Wang, Xiaoqi; Cai, Chuanbing

    2012-01-01

    Photo-gated transistors based on dye-sensitized nanocrystalline titanium dioxide thin film are established. A transistor-like transport behavior characterized by the linear increase, saturated plateau, and breakdown-like increase in the voltage-current curve is achievable with a low driven bias for the present device. The response current exhibits a linear dependence on the intensity of gated light, and the measured maximum photosensitivity is approximately 0.1 A/W. The dynamic responses for various light frequencies and their dependences on the load resistances are investigated as well. The cut-off frequency of ~50 Hz is abstracted, indicating the potential application for economical and efficient light switch or optical communication unit. The dc photo-gated response is explained by the energy level diagram, and is numerically simulated by an equivalent circuit model, suggesting a clear correlation between photovoltaic and photoconductive behaviors as well as their optical responses.

  11. Polymer thin-film transistor based on a high dielectric constant gate insulator

    Science.gov (United States)

    Lü, Wen; Peng, Jun-Biao; Yang, Kai-Xia; Lan, Lin-Feng; Niu, Qiao-Li; Cao, Yong

    2007-04-01

    In this paper full polymer thin-film transistors (PTFTs) based on Poly (acrylonitrile) (PAN) as the gate dielectric and poly (2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene-vinylene) (MEH-PPV) as the semiconductor layer were investigated by using different channel width/length ratios. Relatively high dielectric constant of the polymer dielectric layer (6.27) can remarkably reduce the threshold voltage of the transistors to below -3 V. Hole field-effect mobility of MEH-PPV of the PTFTs was about 4.8×10-4cm2/Vs, and on/off current ratio was larger than 102, which was comparable with that of transistors with widely used Poly (4-vinyl phenol) (PVP) or SiO2 as gate dielectrics.

  12. Polymer thin-film transistor based on a high dielectric constant gate insulator

    Institute of Scientific and Technical Information of China (English)

    Lü Wen; Peng Jun-Biao; Yang Kai-Xia; Lan Lin-Feng; Niu Qiao-Li; Cao Yong

    2007-01-01

    In this paper full polymer thin-film transistors (PTFTs) based on Poly (acrylonitrile) (PAN) as the gate dielectric and poly (2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene-vinylene) (MEH-PPV) as the semiconductor layer were investigated by using different channel width/length ratios. Relatively high dielectric constant of the polymer dielectric layer (6.27) can remarkably reduce the threshold voltage of the transistors to below-3 V. Hole field-effect mobility of MEH-PPV of the PTFTs was about 4.8 × 10-4 cm2/Vs, and on/off current ratio was larger than 102, which was comparable with that of transistors with widely used Poly (4-vinyl phenol) (PVP) or SiO2 as gate dielectrics.

  13. In situ silicon oxide based intermediate reflector for thin-film silicon micromorph solar cells

    Science.gov (United States)

    Buehlmann, P.; Bailat, J.; Dominé, D.; Billet, A.; Meillaud, F.; Feltrin, A.; Ballif, C.

    2007-10-01

    We show that SiO-based intermediate reflectors (SOIRs) can be fabricated in the same reactor and with the same process gases as used for thin-film silicon solar cells. By varying input gas ratios, SOIR layers with a wide range of optical and electrical properties are obtained. The influence of the SOIR thickness in the micromorph cell is studied and current gain and losses are discussed. Initial micromorph cell efficiency of 12.2% (Voc=1.40V, fill factor=71.9%, and Jsc=12.1mA/cm2) is achieved with top cell, SOIR, and bottom cell thicknesses of 270, 95, and 1800nm, respectively.

  14. Hall Scaling behavior of Hg- and Tl-based superconducting thin films with columnar defects

    Science.gov (United States)

    Kang, W. N.; Chu, C. W.; Kim, D. H.; Lee, J. U.

    1998-03-01

    We have measured the mixed-state Hall effects of HgBa_2CaCu_2O_6+δ, HgBa_2Ca_2Cu_3O_8+δ, and Tl_2Ba_2CaCu_2O_8+δ thin films with columnar defects. We found the field-independent scaling behavior between the Hall resistivity(ρ_xy) and longitudinal resistivityρ_xx for low and high field regimes. The Hall scaling exponent β in ρ_xy = Aρ_xx^β showed 1.0 ± 0.1 for low field regions, while β showed 2.0 ± 0.05 for high field regions. The observation of β = 1.0 in the low field limits is consistent with the recent theory which is based on the d-wave superconductors. The result will be discussed in the context of the Hall scaling behavior in 2- or 3-dimensional-like systems.

  15. Multianalyte Biosensors for the Simultaneous Determination of Glucose and Galactose Based on Thin Film Electrodes

    Institute of Scientific and Technical Information of China (English)

    Neng Qin JIA; Zong Rang ZHANG; Jiang Zhong ZHU; Guo Xiong ZHANG

    2004-01-01

    A multianalyte biosensor for the simultaneous determination of glucose and galactose was developed by immobilizing glucose oxidase (GOD) and galactose oxidase (GAO) on Nafion-modified thin film platinum disk electrodes. The dual Pt working electrodes with disk shape and the surrounding ring shaped counter electrode were fabricated by thin film technology, which were integrated onto the same microchip. The response of the designed biosensor for glucose and galactose were linear up to 6.0 mmol/L and 3.5 mmol/L with sensitivities of 0.3 (A/mmol/L and 0.12 μA/mmol/L, respectively. No cross-talking effect was observed.

  16. High mobility organic thin-film transistors based on p-p heterojunction buffer layer

    Science.gov (United States)

    Qian, Xianrui; Wang, Tong; Yan, Donghang

    2013-10-01

    The p-p heterojunction of 5, 6, 11, 12-tetraphenylnaphthacene/vanadyl phthalocyanine, which has been used as the buffer layer, is demonstrated. The highest field-effect mobility is 5.1 cm2/Vs, which is one of the highest reported for polycrystalline rubrene thin film transistors. Current versus voltage characteristics of heterojunction diodes are utilized to investigate the charge injection mechanism, revealing the factors that bring about the improvement of carrier injection and the reduction of contact resistance. These results suggest that our approach is very promising to fabricate high performance organic thin-film transistors for practical applications in organic electronics.

  17. WO3 thin film based multiple sensor array for electronic nose application

    International Nuclear Information System (INIS)

    Multiple sensor array comprising 16 x 2 sensing elements were realized using RF sputtered WO3 thin films. The sensor films were modified with a thin layer of sensitizers namely Au, Ni, Cu, Al, Pd, Ti, Pt. The resulting sensor array were tested for their response towards different gases namely H2S, NH3, NO and C2H5OH. The sensor response values measured from the response curves indicates that the sensor array generates a unique signature pattern (bar chart) for the gases. The sensor response values can be used to get both qualitative and quantitative information about the gas

  18. A Review on Development Prospect of CZTS Based Thin Film Solar Cells

    OpenAIRE

    Xiangbo Song; Xu Ji; Ming Li; Weidong Lin; Xi Luo; Hua Zhang

    2014-01-01

    Cu2ZnSnS4 is considered as the ideal absorption layer material in next generation thin film solar cells due to the abundant component elements in the crust being nontoxic and environmentally friendly. This paper summerized the development situation of Cu2ZnSnS4 thin film solar cells and the manufacturing technologies, as well as problems in the manufacturing process. The difficulties for the raw material’s preparation, the manufacturing process, and the manufacturing equipment were illustrate...

  19. WO{sub 3} thin film based multiple sensor array for electronic nose application

    Energy Technology Data Exchange (ETDEWEB)

    Ramgir, Niranjan S., E-mail: niranjanpr@yahoo.com, E-mail: deepakcct1991@gmail.com; Goyal, C. P.; Datta, N.; Kaur, M.; Debnath, A. K.; Aswal, D. K.; Gupta, S. K. [Thin Film Devices Section, Technical Physics Division, Bhabha Atomic Research Centre, Mumbai–400085 (India); Goyal, Deepak, E-mail: niranjanpr@yahoo.com, E-mail: deepakcct1991@gmail.com [Thin Film Devices Section, Technical Physics Division, Bhabha Atomic Research Centre, Mumbai–400085 (India); Centre for Converging Technologies, University of Rajasthan, Jaipur-302004 (India)

    2015-06-24

    Multiple sensor array comprising 16 x 2 sensing elements were realized using RF sputtered WO{sub 3} thin films. The sensor films were modified with a thin layer of sensitizers namely Au, Ni, Cu, Al, Pd, Ti, Pt. The resulting sensor array were tested for their response towards different gases namely H{sub 2}S, NH{sub 3}, NO and C{sub 2}H{sub 5}OH. The sensor response values measured from the response curves indicates that the sensor array generates a unique signature pattern (bar chart) for the gases. The sensor response values can be used to get both qualitative and quantitative information about the gas.

  20. Fabrication and characterization of high-mobility solution-based chalcogenide thin-film transistors

    KAUST Repository

    Mejia, Israel I.

    2013-01-01

    We report device and material considerations for the fabrication of high-mobility thin-film transistors (TFTs) compatible with large-area and inexpensive processes. In particular, this paper reports photolithographically defined n-type TFTs (n-TFTs) based on cadmium sulfide (CdS) films deposited using solution-based techniques. The integration process consists of four mask levels with a maximum processing temperature of 100 °C. The TFT performance was analyzed in terms of the CdS semiconductor thickness and as a function of postdeposition annealing in a reducing ambient. The IonI off ratios are ∼107 with field-effect mobilities of ∼5.3 and ∼4.7cm2V̇s for Al and Au source-drain contacts, respectively, using 70 nm of CdS. Transmission electron microscopy and electron energy loss spectroscopy were used to analyze the CdS-metal interfaces. © 1963-2012 IEEE.

  1. Thin functional conducting polymer films

    OpenAIRE

    Tian, S.

    2005-01-01

    In the present study, thin functional conducting polyaniline (PANI) films, either doped or undoped, patterned or unpatterned, were prepared by different approaches. The properties of the obtained PANI films were investigated in detail by a combination of electrochemistry with several other techniques, such as SPR, QCM, SPFS, diffraction, etc. The sensing applications (especially biosensing applications) of the prepared PANI films were explored. Firstly, the pure PANI films were prepar...

  2. Interfaces and thin films physics

    International Nuclear Information System (INIS)

    The 1988 progress report of the Interfaces and Thin Film Physics laboratory (Polytechnic School France) is presented. The research program is focused on the thin films and on the interfaces of the amorphous semiconductor materials: silicon and silicon germanium, silicon-carbon and silicon-nitrogen alloys. In particular, the following topics are discussed: the basic processes and the kinetics of the reactive gas deposition, the amorphous materials manufacturing, the physico-chemical characterization of thin films and interfaces and the electron transport in amorphous semiconductors. The construction and optimization of experimental devices, as well as the activities concerning instrumentation, are also described

  3. Development and evaluation of gallium nitride-based thin films for x-ray dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Hofstetter, Markus; Thalhammer, Stefan [Helmholtz Zentrum Muenchen, Ingolstaedter Landstrasse 1, 85764 Neuherberg (Germany); Howgate, John; Sharp, Ian D; Stutzmann, Martin, E-mail: stefan.thalhammer@helmholtz-muenchen.de [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall 3, 85748 Garching (Germany)

    2011-06-07

    X-ray radiation plays an important role in medical procedures ranging from diagnostics to therapeutics. Due to the harm such ionizing radiation can cause, it has become common practice to closely monitor the dosages received by patients. To this end, precise online dosimeters have been developed with the dual objectives of monitoring radiation in the region of interest and improving therapeutic methods. In this work, we evaluate GaN thin film high electron mobility heterostructures with sub-mm{sup 2} detection areas as x-ray radiation detectors. Devices were tested using 40-300 kV Bremsstrahlung x-ray sources. We find that the photoconductive device response exhibits a large gain, is almost independent of the angle of irradiation, and is constant to within 2% of the signal throughout this medical diagnostic x-ray range, indicating that these sensors do not require recalibration for geometry or energy. Furthermore, the devices show a high sensitivity to x-ray intensity and can measure in the air kerma rate (free-in-air) range of 1 {mu}Gy s{sup -1} to 10 mGy s{sup -1} with a signal stability of {+-}1% and a linear total dose response over time. Medical conditions were simulated by measurements of device responses to irradiation through human torso phantoms. Direct x-ray imaging is demonstrated using the index finger and wrist sections of a human phantom. The results presented here indicate that GaN-based thin film devices exhibit a wide range of properties, which make them promising candidates for dosimetry applications. In addition, with potential detection volumes smaller than 10{sup -6} cm{sup 3}, they are well suited for high-resolution x-ray imaging. Moreover, with additional engineering steps, these devices can be adapted to potentially provide both in vivo biosensing and x-ray dosimetry.

  4. Preparation of TiO2-based nanotubes/nanoparticles composite thin film electrodes for their electron transport properties

    International Nuclear Information System (INIS)

    The composite thin film electrodes were prepared with one-dimensional (1D) TiO2-B nanotubes (NTs) and zero-dimensional TiO2 nanoparticles (NPs) based on different weight ratios. The electron transport properties of the NTs/NPs composite thin film electrodes applied for dye-sensitized solar cells had been investigated systematically. The results indicated that although the amount of dye adsorption decreased slightly, the devices with the NTs/NPs composite thin film electrodes could obtain higher open-circuit voltage and overall conversion efficiency compared to devices with pure TiO2 NPs electrodes by rational tuning the weight ratio of TiO2-B NTs and TiO2 NPs. When the weight ratio of TiO2-B NTs in the NTs/NPs composite thin film electrodes increased, the density of states and recombination rate decreased. The 1D structure of TiO2-B NTs can provide direct paths for electron transport, resulting in higher electron lifetime, electron diffusion coefficient and electron diffusion length. The composite thin film electrodes possess the merits of the rapid electron transport of TiO2-B NTs and the high surface area of TiO2 NPs, which has great applied potential in the field of photovoltaic devices. - Highlights: • The composite thin film electrodes (CTFEs) were prepared with nanotubes and nanoparticles. • The CTFEs possess the rapid electron transport and high surface area. • The CTFEs exhibit lower recombination rate and longer electron life time. • The CTFEs have great applied potential in the field of photovoltaic devices

  5. Characterization of Laser Beam Shaping Optics Based on Their Ablation Geometry of Thin Films

    Directory of Open Access Journals (Sweden)

    Stefan Rung

    2014-10-01

    Full Text Available Thin film ablation with pulsed nanosecond lasers can benefit from the use of beam shaping optics to transform the Gaussian beam profile with a circular footprint into a Top-Hat beam profile with a rectangular footprint. In general, the quality of the transformed beam profile depends strongly on the beam alignment of the entire laser system. In particular, the adjustment of the beam shaping element is of upmost importance. For an appropriate alignment of the beam shaper, it is generally necessary to observe the intensity distribution near the focal position of the applied focusing optics. Systems with a low numerical aperture (NA can commonly be qualified by means of laser beam profilers, such as a charge-coupled device (CCD camera. However, laser systems for micromachining typically employ focus lenses with a high NA, which generate focal spot sizes of only several microns in diameter. This turns out to be a challenge for common beam profiling measurement systems and complicates the adjustment of the beam shaper strongly. In this contribution, we evaluate the quality of a Top-Hat beam profiling element and its alignment in the working area based on the ablated geometry of single pulse ablation of thin transparent conductive oxides. To determine the best achievable adjustment, we develop a quality index for rectangular laser ablation spots and investigate the influences of different alignment parameters, which can affect the intensity distribution of a Top-Hat laser beam profile.

  6. Thin-Film LSCs Based on PMMA Nanohybrid Coatings: Device Optimization and Outdoor Performance

    Directory of Open Access Journals (Sweden)

    S. M. El-Bashir

    2013-01-01

    Full Text Available This study concerns the design optimization of thin-film luminescent solar concentrators (TLSCs based on polymethylmethacrylate (PMMA/silica nanohybrid films doped with coumarin dyestuffs specialized in coloring plastics. Two designs of TLSCs had been prepared and characterized. The first consists of a transparent nanohybrid layer coated on a fluorescent PMMA substrate. The second design is the ordinary configuration in which fluorescent nanohybrid layer is coated on a transparent PMMA substrate. The investigation of the spectral properties and efficiency parameters recommended the best solar energy conversion efficiency for the second design. The outdoor performance of optimized TLSC was also evaluated under clear sky conditions of Riyadh city, and the hourly values of the optical efficiency, ηopt, were calculated for one year. The best performance was achieved in summer since the short circuit current for PV cell was doubled after being attached to TLSC and the value of ηopt reached 40% which is higher than other values recorded before due to the abundant solar energy potential in the Arabian Peninsula.

  7. Performance analysis of resistive switching devices based on BaTiO3 thin films

    Science.gov (United States)

    Samardzic, Natasa; Kojic, Tijana; Vukmirovic, Jelena; Tripkovic, Djordjije; Bajac, Branimir; Srdic, Vladimir; Stojanovic, Goran

    2016-03-01

    Resitive switching devices, memristors, have recenty attracted much attention due to promising performances and potential applications in the field of logic and memory devices. Here, we present thin film BaTiO3 based memristor fabricated using ink-jet printing technique. Active material is a single layer barium titanate film with thickness of ̴100 nm, sandwitched between metal electodes. Printing parameters were optimized aiming to achieve stable drop flow and uniform printed layer. Current-voltage characteristics show typical memristive behavior with pinched hysteresis loop crossed at the origin, with marked differences between High Resistive State (HRS) and Low Resistive State (LRS). Obtained resistive states are stable during numerous switching processes. The device also shows unipolar switching effect for negative voltage impulses. Variable voltage impulse amplitudes leads to the shifting of the energy levels of electode contacts resulting in changing of the overall current through the device. Structural charcterization have been performed using XRD analysis and SEM micrography. High-temperature current-voltage measurements combined with transport parameter analysis using Hall efect measurement system (HMS 3000) and Impedance Analyzer AC measurements allows deeper insigth into conduction mechanism of ferroelectric memristors.

  8. Oxidation-Based Continuous Laser Writing in Vertical Nano-Crystalline Graphite Thin Films

    Science.gov (United States)

    Loisel, Loïc; Florea, Ileana; Cojocaru, Costel-Sorin; Tay, Beng Kang; Lebental, Bérengère

    2016-05-01

    Nano and femtosecond laser writing are becoming very popular techniques for patterning carbon-based materials, as they are single-step processes enabling the drawing of complex shapes without photoresist. However, pulsed laser writing requires costly laser sources and is known to cause damages to the surrounding material. By comparison, continuous-wave lasers are cheap, stable and provide energy at a more moderate rate. Here, we show that a continuous-wave laser may be used to pattern vertical nano-crystalline graphite thin films with very few macroscale defects. Moreover, a spatially resolved study of the impact of the annealing to the crystalline structure and to the oxygen ingress in the film is provided: amorphization, matter removal and high oxygen content at the center of the beam; sp2 clustering and low oxygen content at its periphery. These data strongly suggest that amorphization and matter removal are controlled by carbon oxidation. The simultaneous occurrence of oxidation and amorphization results in a unique evolution of the Raman spectra as a function of annealing time, with a decrease of the I(D)/I(G) values but an upshift of the G peak frequency.

  9. Solution processed lanthanum aluminate gate dielectrics for use in metal oxide-based thin film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Esro, M.; Adamopoulos, G., E-mail: g.adamopoulos@lancaster.ac.uk [Engineering Department, Lancaster University, Lancaster LA1 4YR (United Kingdom); Mazzocco, R.; Kolosov, O.; Krier, A. [Physics Department, Lancaster University, Lancaster, LA1 4YB (United Kingdom); Vourlias, G. [Physics Department, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Milne, W. I. [Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA (United Kingdom); Department of Electrical and Computing Engineering, University of Canterbury, 4800 Christchurch (New Zealand)

    2015-05-18

    We report on ZnO-based thin-film transistors (TFTs) employing lanthanum aluminate gate dielectrics (La{sub x}Al{sub 1−x}O{sub y}) grown by spray pyrolysis in ambient atmosphere at 440 °C. The structural, electronic, optical, morphological, and electrical properties of the La{sub x}Al{sub 1−x}O{sub y} films and devices as a function of the lanthanum to aluminium atomic ratio were investigated using a wide range of characterization techniques such as UV-visible absorption spectroscopy, impedance spectroscopy, spectroscopic ellipsometry, atomic force microscopy, x-ray diffraction, and field-effect measurements. As-deposited LaAlO{sub y} dielectrics exhibit a wide band gap (∼6.18 eV), high dielectric constant (k ∼ 16), low roughness (∼1.9 nm), and very low leakage currents (<3 nA/cm{sup 2}). TFTs employing solution processed LaAlO{sub y} gate dielectrics and ZnO semiconducting channels exhibit excellent electron transport characteristics with hysteresis-free operation, low operation voltages (∼10 V), high on/off current modulation ratio of >10{sup 6}, subthreshold swing of ∼650 mV dec{sup −1}, and electron mobility of ∼12 cm{sup 2} V{sup −1} s{sup −1}.

  10. Fiber-optic protease sensor based on the degradation of thin gelatin films

    Directory of Open Access Journals (Sweden)

    Bastien Schyrr

    2015-03-01

    Full Text Available Despite increasing interest in situ monitoring of proteolytic activity in chronic wound is not possible and information can only be obtained by sampling wound exudate. In this context, we developed an evanescent wave (EW fiber-optic sensor to quantify protease activity directly in the wound bed. Detection is based on the degradation of thin gelatin films deposited on the fiber core by dip-coating, which serve as a substrate for proteases. After staining with a chlorophyllin copper sodium salt biocompatible dye, EW absorption occurs proportionally to the dye concentration, which is detected by the variation in light transmission intensity. The sensor response varies proportionally to enzymatic activity, showing sensitivity against MMP-2 and MMP-9 down to 2 μg/mL and 10 μg/mL, respectively. In addition, it is sensitive to film thickness and crosslink density, thus allowing tuning of the sensitivity and lifetime. Designed to be totally biocompatible and low cost, this miniature sensor has potential for use as a point-of-care disposable device in a clinical environment to assist physicians with quantitative information about the wound healing process.

  11. Synthesis of novel strontium-based cuprate superconducting thin films, and the relationship between their crystal structures and electrical properties

    Science.gov (United States)

    Chang, Kuo-Wei

    2000-12-01

    Novel Sr-based cuprate thin films were investigated to explore their potential as next generation superconducting materials. Thin films of infinite-layer compound (Sr,Ca)CuO2 (no blocking layer), cuprate oxycarbonate Sr2CuO2(CO3) (carbonate blocking layer), and Tl(Sr,Ba)2Can-1CunOy (n = 2 and 3) (thin blocking layer) were synthesized using metal-organic chemical vapor deposition. The structure and defect chemistry of the blocking layers of these cuprate compounds were found to have profound effects on the transport properties both in the normal state and the superconducting state. Phase pure, epitaxial infinite-layer compound (Sr1-xCa x)CuO2 thin films were deposited on SrTiO3(100) substrates. However, these films were always semiconducting with resistivities of the order of 1 ohm- cm and with carrier concentrations of 1017~10 19cm-3, which is two to four orders of magnitude lower than the typical superconducting cuprates. The low carrier concentration was attributed to the absence of blocking layers containing a sufficient concentration of charged defects. Transport was via variable range hopping conduction. By annealing in air, the infinite-layer compound SrCuO2 thin films reacted with the CO2 in air to generate Sr 2CuO2(CO3) thin films. Upon formation of carbonate blocking layers, charger carriers were introduced into the Sr2CuO 2(CO3) thin films through the partial substitution of carbon by copper or boron in the SrCO3 blocking layers. After oxygen annealing or upon boron substitution, the carrier concentration increased up to 10 21 cm-3. A superconducting onset temperature of 34K and a zero resistivity temperature of 20K have been observed for Sr 2CuO2(C1-xBx)O3 thin films. A critical carrier density of 0.10~0.12 holes/Cu was required to render superconductivity. The effect of crystal structure on the critical current density was investigated by measuring the vortex pinning energies of Tl2Ba2CaCu 2Oy (Tl-2212) and Tl(Sr,Ba)2Ca Cu2O y (Tl- (Sr,Ba)1212) thin

  12. Current Progress of Hf (Zr)-Based High-k Gate Dielectric Thin Films

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    With the continued downscaling of complementary metal-oxide-semiconductor field effect transistor dimensions, high-dielectric constant (high-k) gate materials, as alternatives to SiO2, have been extensively investigated. Hf (Zr)-based high-k gate dielectric thin films have been regarded as the most promising candidates for high-k gate dielectric according to the International Technology Roadmap for Semiconductor due to their excellent physical properties and performance. This paper reviews the recent progress on Hf (Zr)-based high-k gate dielectrics based on PVD (physical vapor deposition) process. This article begins with a survey of various methods developed for generating Hf (Zr)-based high-k gate dielectrics, and then mainly focuses on microstructure, synthesis, characterization, formation mechanisms of interfacial layer, and optical properties of Hf (Zr)-based high-k gate dielectrics. Finally, this review concludes with personal perspectives towards future research on Hf (Zr)-based high-k gate dielectrics.

  13. Fabrication of semi-transparent superoleophobic thin film from fabrics and nanoparticle-based hierarchical structure

    OpenAIRE

    Nishizawa S.; Shiratori S.

    2013-01-01

    Superoleophobic thin films have many potential applications including fluid transfer, fluid power systems, stain resistant and antifouling materials, and microfluidics among others. Transparency is also desired with superhydrophobicity for their numerous applications; however transparency and oleophobicity are almost incompatible relationship with each other in the point of surface structure. Because oleophobicity required rougher structure at nano-micro scale than hydrophobicity, and these r...

  14. Silicon-based thin-film transistors with a high stability

    NARCIS (Netherlands)

    Stannowski, Bernd

    2002-01-01

    Thin-Film Transistors (TFTs) are widely applied as pixel-addressing devices in large-area electronics, such as active-matrix liquid-crystal displays (AMLCDs) or sensor arrays. Hydrogenated amorphous silicon (a-Si:H) and silicon nitride (a-SiNx:H) are generally used as the semiconductor and the insul

  15. Nanoparticles and Nanostructured Thin Films Based on Strong Polycations of Integral type

    Institute of Scientific and Technical Information of China (English)

    E. S. Dragan; M. Mihai; S. Schwarz

    2005-01-01

    @@ 1Introduction Nonstoichiometric interpolyelectrolyte complexes (NIPECs) as nanoparticles, on the one side, and nanostructured thin films with controlled architecture, deposited on some planar surfaces, on the other side,have been designed by eco-friendly techniques using strong polycations (PC) containing quaternary ammonium groups in the backbone and either strong polyanions or multicharged azo dyes.

  16. Real-time Holographic Display Based on a Super Fast Response Thin Film

    International Nuclear Information System (INIS)

    Real-time dynamic holographic display is obtained with super fast response in a thin film without any applied electric field. Holograms can be refreshed in the order of a millisecond and there is no cross talk between the recorded holograms because the hologram formed in the film is transient and can be completely self erased, and the hologram formation time and self-erasure time are both ∼1 ms. Holographic video display is achieved, which shows the real-time holographic image display capability of the thin film, and its much higher resolution than those of commercially available spatial light modulators. Furthermore, multiplexed hologram display using two polarization directions of a recorded light and multiple color holographic display at different laser wavelengths are presented, which demonstrate the feasibility of a RGB color holographic three-dimensional display with the thin film. Because the sample is easy to be fabricated into a large size screen and needs no external applied electric field, we think that the film can be developed into a large-size, dynamic, and color holographic three-dimensional display in the future.

  17. Thin-film photovoltaic partnership -- CIS-based thin film PV technology: Final technical report, September 1995--December 1998

    Energy Technology Data Exchange (ETDEWEB)

    Tarrant, D.E.; Gay, R.R.

    1999-10-26

    Siemens Solar Industries (SSI) achieved outstanding progress toward NREL/DOE goals during this subcontract. The statistical process control methodology was applied, and it demonstrated process reproducibility and yields for a 10-cm {times} 10-cm substrate size baseline process. Based on an understanding of the importance of materials of construction and the physical layout for absorber formation reactors, SSI designed and built a replacement large-area reactor based on a more direct scale-up of the baseline reactor. While designing and building the new large-area reactor, SSI defined and demonstrated new package designs to combine 10-cm {times} 30-cm circuit plates into one package; this allowed SSI to deliver large-area prototype modules to NREL for evaluation, and to introduce the first CIS-based products--5-watt (ST5) and 10-watt (ST10) modules. After completion of the new large-area reactor, all processes were scaled to a 30-cm {times} 120-cm plate size. Subsequently, only large 30-cm {times} 120-cm circuit plates were fabricated for 30-cm {times} 120-cm prototype modules or, after cutting the large circuit plates into smaller circuit plates, for the two new CIS-based products. The scaled process exhibits generally good control for extended periods with periodic shifts in the short-term process average that appears to result from batch-to-batch variability in precursor or base electrode preparation. Similarly, periodic shunting along the laser-scribed pattern lines in the Mo base electrode appears to result from batch-to-batch variability in base electrode preparation. Significant progress was made in understanding transient effects in CIS devices. Transient effects are important for many topics, including accelerated testing, process definition, measurement protocols, process predictability, interpretation of experimental test results, and understanding of device structures. Long-term outdoor stability of CIS continues to be demonstrated at NREL where 30-cm

  18. Si-based thin film coating on Y-TZP: Influence of deposition parameters on adhesion of resin cement

    Energy Technology Data Exchange (ETDEWEB)

    Queiroz, José Renato Cavalcanti, E-mail: joserenatocq@hotmail.com [Potiguar University, Department of Biotechnology, Natal (Brazil); Nogueira Junior, Lafayette [São Paulo State University, Department of Prosthodontics and Dental Materials, São José dos Campos (Brazil); Massi, Marcos [Federal University of São Paulo, Institute of Science and Technology, São José dos Campos (Brazil); Silva, Alecssandro de Moura; Bottino, Marco Antonio [São Paulo State University, Department of Prosthodontics and Dental Materials, São José dos Campos (Brazil); Sobrinho, Argemiro Soares da Silva [Technological Institute of Aeronautics, Department of Physics, São José dos Campos (Brazil); Özcan, Mutlu [University of Zurich, Dental Materials Unit, Center for Dental and Oral Medicine, Clinic for Fixed and Removable Prosthodontics and Dental Materials Science, Zurich (Switzerland)

    2013-10-01

    This study evaluated the influence of deposition parameters for Si-based thin films using magnetron sputtering for coating zirconia and subsequent adhesion of resin cement. Zirconia ceramic blocks were randomly divided into 8 groups and specimens were either ground finished and polished or conditioned using air-abrasion with alumina particles coated with silica. In the remaining groups, the polished specimens were coated with Si-based film coating with argon/oxygen magnetron discharge at 8:1 or 20:1 flux. In one group, Si-based film coating was performed on air-abraded surfaces. After application of bonding agent, resin cement was bonded. Profilometry, goniometry, Energy Dispersive X-ray Spectroscopy and Rutherford Backscattering Spectroscopy analysis were performed on the conditioned zirconia surfaces. Adhesion of resin cement to zirconia was tested using shear bond test and debonded surfaces were examined using Scanning Electron Microscopy. Si-based film coating applied on air-abraded rough zirconia surfaces increased the adhesion of the resin cement (22.78 ± 5.2 MPa) compared to those of other methods (0–14.62 MPa) (p = 0.05). Mixed type of failures were more frequent in Si film coated groups on either polished or air-abraded groups. Si-based thin films increased wettability compared to the control group but did not change the roughness, considering the parameters evaluated. Deposition parameters of Si-based thin film and after application of air-abrasion influenced the initial adhesion of resin cement to zirconia.

  19. Si-based thin film coating on Y-TZP: Influence of deposition parameters on adhesion of resin cement

    Science.gov (United States)

    Queiroz, José Renato Cavalcanti; Nogueira Junior, Lafayette; Massi, Marcos; Silva, Alecssandro de Moura; Bottino, Marco Antonio; Sobrinho, Argemiro Soares da Silva; Özcan, Mutlu

    2013-10-01

    This study evaluated the influence of deposition parameters for Si-based thin films using magnetron sputtering for coating zirconia and subsequent adhesion of resin cement. Zirconia ceramic blocks were randomly divided into 8 groups and specimens were either ground finished and polished or conditioned using air-abrasion with alumina particles coated with silica. In the remaining groups, the polished specimens were coated with Si-based film coating with argon/oxygen magnetron discharge at 8:1 or 20:1 flux. In one group, Si-based film coating was performed on air-abraded surfaces. After application of bonding agent, resin cement was bonded. Profilometry, goniometry, Energy Dispersive X-ray Spectroscopy and Rutherford Backscattering Spectroscopy analysis were performed on the conditioned zirconia surfaces. Adhesion of resin cement to zirconia was tested using shear bond test and debonded surfaces were examined using Scanning Electron Microscopy. Si-based film coating applied on air-abraded rough zirconia surfaces increased the adhesion of the resin cement (22.78 ± 5.2 MPa) compared to those of other methods (0-14.62 MPa) (p = 0.05). Mixed type of failures were more frequent in Si film coated groups on either polished or air-abraded groups. Si-based thin films increased wettability compared to the control group but did not change the roughness, considering the parameters evaluated. Deposition parameters of Si-based thin film and after application of air-abrasion influenced the initial adhesion of resin cement to zirconia.

  20. Thin-film solar cell

    NARCIS (Netherlands)

    Metselaar, J.W.; Kuznetsov, V.I.

    1998-01-01

    The invention relates to a thin-film solar cell provided with at least one p-i-n junction comprising at least one p-i junction which is at an angle alpha with that surface of the thin-film solar cell which collects light during operation and at least one i-n junction which is at an angle beta with t

  1. Centrifugation-based Purification of Emerging Low-dimensional Materials and Their Thin-film Applications

    Science.gov (United States)

    Seo, Jung Woo

    Polydispersity in low-dimensional materials offers many interesting challenges and properties. In particular, the one- and two-dimensional carbon allotropes such as carbon nanotubes and graphene have demonstrated exquisite optoelectronic properties that are highly sensitive to their physical structures, where subtle variations in diameter and thickness render them with significantly different electronic band structures. Thus, the carbon nanomaterials have been the subject of extensive studies that address their polydispersity issues. Among these, solution-phase, buoyant density-based methods such as density gradient ultracentrifugation have been widely utilized to enrich subpopulations of carbon nanotubes and graphene with narrow distribution in diameter and thickness, enabling their applications in various next-generation thin-film devices. In this thesis, I present further advancement of centrifugation-based processing methods for emerging low-dimensional materials through systematic utilization of previously explored surfactant systems, development of novel surfactant types, and study of correlation between the chemical structure of surfactants and the dispersion and optoelectronic properties of the nanomaterials. First, I employ an iterative density gradient ultracentrifugation with a combination of anionic surfactants and addition of excess counter-ions to achieve isolation of novel diameter species of semiconducting single-walled carbon nanotubes. The purification of carbon nanotubes with simultaneous, ultrahigh-purity refinement in electronic type and diameter distribution leads to collaborative studies on heat distribution characteristics and diameter-dependent direct current and radio frequency performances in monodisperse carbon nanotube thin-film transistors. Next, I develop the use of non-ionic polymeric surfactants for centrifugation-based processes. Specifically, I utilize polypropylene and polyethylene oxide-based block copolymers with density

  2. The development of Tl-2212 based superconducting thin films for microwave applications

    CERN Document Server

    Hyland, D M C

    2001-01-01

    This thesis attempts to develop the understanding of the two-stage ex-situ processing of Tl sub 2 Ba sub 2 CaCu sub 2 O (Tl-2212) thin films on LaAlO sub 3 substrates. Initially a thallium-free precursor film is deposited by sputtering, this is then annealed in a sealed crucible containing a thallium source to produce the final crystalline film. An investigation into the correlation of physical characteristics of the films with their microwave properties is presented. High reproducibility of processing was achieved for 1cm sup 2 size films with measured R sub s < 0.5m OMEGA. Strong dependence of the microwave properties was found with film thickness and growth morphology of the crystalline film. A good correlation of R sub s was seen with defect density, greater numbers of defects giving higher R sub s values. Problems were encountered in scaling up the process to fabricate 2-inch diameter films, initially limited by the increased defect density associated with a larger surface area. Additionally when usin...

  3. Fabrication of graphene thin films based on layer-by-layer self-assembly of functionalized graphene nanosheets.

    Science.gov (United States)

    Park, Je Seob; Cho, Sung Min; Kim, Woo-Jae; Park, Juhyun; Yoo, Pil J

    2011-02-01

    In this study, we present a facile means of fabricating graphene thin films via layer-by-layer (LbL) assembly of charged graphene nanosheets (GS) based on electrostatic interactions. To this end, graphite oxide (GO) obtained from graphite powder using Hummers method is chemically reduced to carboxylic acid-functionalized GS and amine-functionalized GS to perform an alternate LbL deposition between oppositely charged GSs. Specifically, for successful preparation of positively charged GS, GOs are treated with an intermediate acyl-chlorination reaction by thionyl chloride and a subsequent amidation reaction in pyridine, whereby a stable GO dispersibility can be maintained within the polar reaction solvent. As a result, without the aid of additional hybridization with charged nanomaterials or polyelectrolytes, the oppositely charged graphene nanosheets can be electrostatically assembled to form graphene thin films in an aqueous environment, while obtaining controllability over film thickness and transparency. Finally, the electrical property of the assembled graphene thin films can be enhanced through a thermal treatment process. Notably, the introduction of chloride functions during the acyl-chlorination reaction provides the p-doping effect for the assembled graphene thin films, yielding a sheet resistance of 1.4 kΩ/sq with a light transmittance of 80% after thermal treatment. Since the proposed method allows for large-scale production as well as elaborate manipulation of the physical properties of the graphene thin films, it can be potentially utilized in various applications, such as transparent electrodes, flexible displays and highly sensitive biosensors. PMID:21207942

  4. Niobium Thin Film Characterization for Thin Film Technology Used in Superconducting Radiofrequency Cavities

    Science.gov (United States)

    Dai, Yishu; Valente-Feliciano, Anne-Marie

    2015-10-01

    Superconducting RadioFrequency (SRF) penetrates about 40-100 nm of the top surface, making thin film technology possible in producing superconducting cavities. Thin film is based on the deposition of a thin Nb layer on top of a good thermal conducting material such as Al or Cu. Thin film allows for better control of the surface and has negligible response to the Earth's magnetic field, eliminating the need for magnetic shielding of the cavities. Thin film superconductivity depends heavily on coating process conditions, involving controllable parameters such as crystal plane orientation, coating temperature, and ion energy. MgO and Al2O3 substrates are used because they offer very smooth surfaces, ideal for studying film growth. Atomic Force Microscopy is used to characterize surface's morphology. It is evident that a lower nucleation energy and a long coating time increases the film quality in the r-plane sapphire crystal orientation. The quality of the film increases with thickness. Nb films coated on r-plane, grow along the (001) plane and yield a much higher RRR compared to the films grown on a- and c-planes. This information allows for further improvement on the research process for thin film technology used in superconducting cavities for the particle accelerators. National Science Foundation, Department of Energy, Jefferson Lab, Old Dominion University.

  5. Ceramics and amorphous thin films based on gallium sulphide doped by rare-earth sulphides

    International Nuclear Information System (INIS)

    Bulk ceramics of Ga2S3 and rare-earth sulfides (EuS, Gd2S3, Er2S3) as well as combinations thereof have been prepared by spark plasma sintering (SPS). The disk-shaped ceramics were used as targets for pulsed laser deposition (PLD) experiments to obtain amorphous thin films. The properties of these new bulks and amorphous thin films have been investigated by x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), optical transmission spectroscopy, and atomic force microscopy (AFM). In order to test the photoexpansion effect in Ga2S3 and the possibility to create planar arrays of microlenses, the film was irradiated with femtosecond laser pulses at different powers. For low laser power pulses (up to 100 mW power per pulse) a photoexpansion effect was observed, which leads to formation of hillocks with a height of 40–50 nm. EuS doped Ga2S3 thin film shows luminescence properties, which recommend them for optoelectronic applications. (invited article)

  6. Grain Boundary Induced Bias Instability in Soluble Acene-Based Thin-Film Transistors

    Science.gov (United States)

    Nguyen, Ky V.; Payne, Marcia M.; Anthony, John E.; Lee, Jung Hun; Song, Eunjoo; Kang, Boseok; Cho, Kilwon; Lee, Wi Hyoung

    2016-09-01

    Since the grain boundaries (GBs) within the semiconductor layer of organic field-effect transistors (OFETs) have a strong influence on device performance, a substantial number of studies have been devoted to controlling the crystallization characteristics of organic semiconductors. We studied the intrinsic effects of GBs within 5,11-bis(triethylsilylethynyl) anthradithiophene (TES-ADT) thin films on the electrical properties of OFETs. The GB density was easily changed by controlling nulceation event in TES-ADT thin films. When the mixing time was increased, the number of aggregates in as-spun TES-ADT thin films were increased and subsequent exposure of the films to 1,2-dichloroethane vapor led to a significant increase in the number of nuleation sites, thereby increasing the GB density of TES-ADT spherulites. The density of GBs strongly influences the angular spread and crystallographic orientation of TES-ADT spherulites. Accordingly, the FETs with higher GB densities showed much poorer electrical characteristics than devices with lower GB density. Especially, GBs provide charge trapping sites which are responsible for bias-stress driven electrical instability. Dielectric surface treatment with a polystyrene brush layer clarified the GB-induced charge trapping by reducing charge trapping at the semiconductor-dielectric interface. Our study provides an understanding on GB induced bias instability for the development of high performance OFETs.

  7. Size effects in thin films

    CERN Document Server

    Tellier, CR; Siddall, G

    1982-01-01

    A complete and comprehensive study of transport phenomena in thin continuous metal films, this book reviews work carried out on external-surface and grain-boundary electron scattering and proposes new theoretical equations for transport properties of these films. It presents a complete theoretical view of the field, and considers imperfection and impurity effects.

  8. Carbon Nanotube Thin-Film Antennas.

    Science.gov (United States)

    Puchades, Ivan; Rossi, Jamie E; Cress, Cory D; Naglich, Eric; Landi, Brian J

    2016-08-17

    Multiwalled carbon nanotube (MWCNT) and single-walled carbon nanotube (SWCNT) dipole antennas have been successfully designed, fabricated, and tested. Antennas of varying lengths were fabricated using flexible bulk MWCNT sheet material and evaluated to confirm the validity of a full-wave antenna design equation. The ∼20× improvement in electrical conductivity provided by chemically doped SWCNT thin films over MWCNT sheets presents an opportunity for the fabrication of thin-film antennas, leading to potentially simplified system integration and optical transparency. The resonance characteristics of a fabricated chlorosulfonic acid-doped SWCNT thin-film antenna demonstrate the feasibility of the technology and indicate that when the sheet resistance of the thin film is >40 ohm/sq no power is absorbed by the antenna and that a sheet resistance of antenna. The dependence of the return loss performance on the SWCNT sheet resistance is consistent with unbalanced metal, metal oxide, and other CNT-based thin-film antennas, and it provides a framework for which other thin-film antennas can be designed.

  9. TTF/TCNQ-based thin films and microcrystals. Growth and charge transport phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Solovyeva, Vita

    2011-05-26

    The thesis adresses several problems related to growth and charge transport phenomena in thin films of TTF-TCNQ and (BEDT-TTF)TCNQ. The following main new problems are addressed: - The influence of thin-film specific factors, such as the substrate material and growth-induced defects, on the Peierls transition temperature in TTF-TCNQ thin films was studied; - finite-size effects in TTF-TCNQ were investigated by considering transport properties in TTF-TCNQ microcrystals. The influence of the size of the crystal on the Peierls transition temperature was studied. In this context a new method of microcontact fabrication was employed to favor the measurements; - an analysis of radiation-induced defects in TTF-TCNQ thin films and microcrystals was performed. It was demonstrated than an electron beam can induce appreciable damage to the sample such that its electronic properties are strongly modified; - a bilayer growth method was established to fabricate (BEDT-TTF)TCNQ from the gas phase. This newly developed bilayer growth method was showed to be suitable for testing (BEDT-TTF)TCNQ charge-transfer phase formation; - the structure of the formed (BEDT-TTF)TCNQ charge-transfer compounds was analyzed by using a wide range of experimental techniques. An overview and the description of the basic physical principles underlying charge-transfer compounds is given in chapter 2. Experimental techniques used for the growth and characterization of thin films and microcrystals are presented in chapter 3. Chapter 4 gives an overview of the physical properties of the studied organic materials. Chapter 5 discussed the experimental study of TTF-TCNQ thin films. he Peierls transition in TTF-TCNQ is a consequence of the quasi-one-dimensional structure of the material and depends on different factors, studied in chapters 5 and 6. In contradistinction to TTF-TTCNQ, the (BEDT-TTF)TCNQ charge-transfer compound crystallizes in several different modifications with different physical properties

  10. Sensitivity enhancement of OD- and OD-CNT-based humidity sensors by high gravity thin film deposition technique

    International Nuclear Information System (INIS)

    The humidity sensing properties of the thin films of an organic semiconductor material orange dye (OD) and its composite with CNTs deposited at high gravity conditions have been reported. Impedance, phase angle, capacitance and dissipation of the samples were measured at 1 kHz and room temperature conditions. The impedance decreases and capacitance increases with an increase in the humidity level. It was found that the sensitivity of the OD-based thin film samples deposited at high gravity condition is higher than the samples deposited at low gravity condition. The impedances and capacitance sensitivities of the of the samples deposited under high gravity condition are 6.1 times and 1.6 times higher than the films deposited under low gravity condition. (paper)

  11. Sol-Gel Deposited Porogen Based Porous Low-k Thin Films for Interlayer Dielectric Application in ULSI Circuits

    Directory of Open Access Journals (Sweden)

    Yogesh S. Mhaisagar

    2012-10-01

    Full Text Available Porous SiO2 low-k thin films with low dielectric constant were successfully deposited by sol-gel spin-coating technique. The films were deposited by using Tertaethylorthosilicate (TEOS as a precursor solution and HF was used as an acid catalyst solution. The Tween80 with different volumetric concentrations i.e. 0.0 ml, 0.5 ml and 0.7 ml was used as a pore generator to lower the dielectric constant of the films by introducing the porosity in the films matrix. The thickness and refractive index (RI of low-k thin films have been measured by Ellipsometer. The refractive index and thickness of the films observed to be decreasing with increase in Tween80 concentration. The chemical bonding structures of films were analyzed by using Fourier transform infrared spectroscopy (FT-IR spectroscopy and the stretching, bending and rocking peaks appear at 1077 cm – 1, 967  cm – 1, 447  cm – 1 respectively confirm the formation of Si-O-Si network. The RIs of the films deposited at 0 ml, 0.5 ml and at 0.7 ml of Tween80 concentration are found to be 1.34, 1.26, and 1.20 respectively. Based on RI values of the films, the porosity percentage, density and dielectric constant have been calculated by standard formulation method. The increase in porosity percentage of films from 3 % to 55 % with increase in Tween80 concentration reveals that, the most of the hydroxyl group and porogen get evaporated and form more voids in the films. This increase in porosity percentage causes to lower the dielectric constant of films and was found to be 2.26 at the 0.7 ml of Tween80 concentration. Such porogen based low dialectic constant thin films can be suitable for interlayer dielectric (ILD applications in ULSI circuits.

  12. Nanotemplated lead telluride thin films

    OpenAIRE

    Li, Xiaohong; Nandhakumar, Iris S.; Attard, George S.; Markham, Matthew L.; Smith, David C.; Baumberg, Jeremy J.

    2009-01-01

    Direct lyotropic liquid crystalline templating has been successfully applied to produce nanostructured IV–VI semiconductor PbTe thin films by electrodeposition both on gold and n-type (100) silicon substrates. The PbTe films were characterized by transmission electron microscopy, X-ray diffraction and polarized optical microscopy and the results show that the films have a regular hexagonal nanoarchitecture with a high crystalline rock salt structure and exhibit strong birefringenc...

  13. Thin films and froth flotation

    International Nuclear Information System (INIS)

    The properties of thin, aqueous films on solid surfaces and their central role in the froth flotation process are discussed. The stability of these films can generally be described in terms of electrostatic and van der Waals forces. Significant experimental and theoretical advances are required in many areas (e.g. short range forces, film drainage) before a clear picture of the collision of, adhesion between and detachment of bubbles and particles will emerge. (orig.)

  14. A novel epitaxially grown LSO-based thin-film scintillator for micro-imaging using hard synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Douissard, P.A.; Martin, T.; Chevalier, V.; Rack, A. [European Synchrotron Radiat Facil, F-38043 Grenoble, (France); Cecilia, A.; Baumbach, T.; Rack, A. [Karlsruhe Inst Technol ANKA, D-76021 Karlsruhe, (Germany); Couchaud, M. [CEA LETI, F-38054 Grenoble, (France); Dupre, K. [FEE GmbH, D-55743 Idar Oberstein, (Germany); Kuhbacher, M. [Helmholtz Zentrum Berlin Mat and Energie, D-14109 Berlin, (Germany)

    2010-07-01

    The efficiency of high-resolution pixel detectors for hard X-rays is nowadays one of the major criteria which drives the feasibility of imaging experiments and in general the performance of an experimental station for synchrotron-based microtomography and radiography. Here the luminescent screen used for the indirect detection is focused on in order to increase the detective quantum efficiency a novel scintillator based on doped Lu{sub 2}SiO{sub 5} (LSO), epitaxially grown as thin film via the liquid phase epitaxy technique. It is shown that, by using adapted growth and doping parameters as well as a dedicated substrate, the scintillation behaviour of a LSO-based thin crystal together with the high stopping power of the material allows for high-performance indirect X-ray detection. In detail, the conversion efficiency, the radioluminescence spectra, the optical absorption spectra under UV/visible-light and the afterglow are investigated. A set-up to study the effect of the thin-film scintillator's temperature on its conversion efficiency is described as well it delivers knowledge which is important when working with higher photon flux densities and the corresponding high heat load on the material. Additionally, X-ray imaging systems based on different diffraction-limited visible-light optics and CCD cameras using among others LSO-based thin film are compared. Finally, the performance of the LSO thin film is illustrated by imaging a honey bee leg, demonstrating the value of efficient high-resolution computed tomography for life sciences. (authors)

  15. A thermochromic thin film based on host-guest interactions in a layered double hydroxide.

    Science.gov (United States)

    Wang, Xinrui; Lu, Jun; Shi, Wenying; Li, Feng; Wei, Min; Evans, David G; Duan, Xue

    2010-01-19

    Optically transparent thin films with thermochromic properties have been fabricated by means of cointercalation of different molar ratios of 4-(4-anilinophenylazo)benzenesulfonate (AO5) and sodium dodecylbenzene sulfonate (SDS) into the galleries of a ZnAl layered double hydroxide (LDH). The X-ray diffraction (XRD) patterns of these thin films show that they are assembled in a highly c-oriented manner, and the basal spacing ranges from 2.95 to 2.63 nm with varying AO5/SDS molar ratio. The preferential orientation of AO5 in the galleries of 10% AO5-LDH (AO5/SDS = 10:90, molar percentage) was evaluated by the fluorescence polarization technique; the results show that AO5 anions are accommodated between sheets of ZnAl-LDH as monomeric units with a tilt angle Psi (defined as the angle between the transition dipole moment of the AO5 anion with respect to the normal to the LDH layer) of 74 degrees. It was found that the composite film exhibits marked thermochromic behavior (light yellow reddish-orange) in the temperature range of 35-65 degrees C, which is reversible over a number of heating-cooling cycles. It has been demonstrated that the thermochromic behavior results from tautomerism of interlayer AO5 and furthermore that both the host-guest and guest-guest interactions are key factors, since pristine AO5 shows no thermochromic performance. The 10% AO5-LDH film shows the highest thermochromic efficiency of all the films examined. Furthermore, a reversible contraction and expansion of the LDH basal spacing was also observed for this thin film over the same temperature range. PMID:19761228

  16. Photodiode Based on CdO Thin Films as Electron Transport Layer

    Science.gov (United States)

    Soylu, M.; Kader, H. S.

    2016-08-01

    Cadmium oxide (CdO) thin films were synthesized by the sol-gel method. The films were analyzed by means of XRD, AFM, and UV/Vis spectrophotometry. X-ray diffraction patterns confirm that the films are formed from CdO with cubic crystal structure and consist of nano-particles. The energy gap of the prepared film was found to be 2.29 eV. The current-voltage (I-V) characteristics of the CdO/p-Si heterojunction were examined in the dark and under different illumination intensities. The heterojunction showed high rectifying behavior and a strong photoresponse. Main electrical parameters of the photodiode such as series and shunt resistances (R s and R sh), saturation current I 0, and photocurrent I ph, were extracted considering a single diode equivalent circuit of a photovoltaic cell. Results indicate that the application of CdO thin films as an electron transport layer on p-Si acts as a photodetector in the field of the UV/visible.

  17. Photodiode Based on CdO Thin Films as Electron Transport Layer

    Science.gov (United States)

    Soylu, M.; Kader, H. S.

    2016-11-01

    Cadmium oxide (CdO) thin films were synthesized by the sol-gel method. The films were analyzed by means of XRD, AFM, and UV/Vis spectrophotometry. X-ray diffraction patterns confirm that the films are formed from CdO with cubic crystal structure and consist of nano-particles. The energy gap of the prepared film was found to be 2.29 eV. The current-voltage ( I- V) characteristics of the CdO/ p-Si heterojunction were examined in the dark and under different illumination intensities. The heterojunction showed high rectifying behavior and a strong photoresponse. Main electrical parameters of the photodiode such as series and shunt resistances ( R s and R sh), saturation current I 0, and photocurrent I ph, were extracted considering a single diode equivalent circuit of a photovoltaic cell. Results indicate that the application of CdO thin films as an electron transport layer on p-Si acts as a photodetector in the field of the UV/visible.

  18. Flexible thin-film battery based on graphene-oxide embedded in solid polymer electrolyte

    Science.gov (United States)

    Kammoun, M.; Berg, S.; Ardebili, H.

    2015-10-01

    Enhanced safety of flexible batteries is an imperative objective due to the intimate interaction of such devices with human organs such as flexible batteries that are integrated with touch-screens or embedded in clothing or space suits. In this study, the fabrication and testing of a high performance thin-film Li-ion battery (LIB) is reported that is both flexible and relatively safer compared to the conventional electrolyte based batteries. The concept is facilitated by the use of solid polymer nanocomposite electrolyte, specifically, composed of polyethylene oxide (PEO) matrix and 1 wt% graphene oxide (GO) nanosheets. The flexible LIB exhibits a high maximum operating voltage of 4.9 V, high capacity of 0.13 mA h cm-2 and an energy density of 4.8 mW h cm-3. The battery is encapsulated using a simple lamination method that is economical and scalable. The laminated battery shows robust mechanical flexibility over 6000 bending cycles and excellent electrochemical performance in both flat and bent configurations. Finite element analysis (FEA) of the LIB provides critical insights into the evolution of mechanical stresses during lamination and bending.Enhanced safety of flexible batteries is an imperative objective due to the intimate interaction of such devices with human organs such as flexible batteries that are integrated with touch-screens or embedded in clothing or space suits. In this study, the fabrication and testing of a high performance thin-film Li-ion battery (LIB) is reported that is both flexible and relatively safer compared to the conventional electrolyte based batteries. The concept is facilitated by the use of solid polymer nanocomposite electrolyte, specifically, composed of polyethylene oxide (PEO) matrix and 1 wt% graphene oxide (GO) nanosheets. The flexible LIB exhibits a high maximum operating voltage of 4.9 V, high capacity of 0.13 mA h cm-2 and an energy density of 4.8 mW h cm-3. The battery is encapsulated using a simple lamination method

  19. How do evaporating thin films evolve? Unravelling phase-separation mechanisms during solvent-based fabrication of polymer blends

    KAUST Repository

    Wodo, Olga

    2014-10-13

    © 2014 AIP Publishing LLC. Solvent-based fabrication is a flexible and affordable approach to manufacture polymer thin films. The properties of products made from such films can be tailored by the internal organization (morphology) of the films. However, a precise knowledge of morphology evolution leading to the final film structure remains elusive, thus limiting morphology control to a trial and error approach. In particular, understanding when and where phases are formed, and how they evolve would provide rational guidelines for more rigorous control. Here, we identify four modes of phase formation and subsequent propagation within the thinning film during solvent-based fabrication. We unravel the origin and propagation characteristics of each of these modes. Finally, we construct a mode diagram that maps processing conditions with individual modes. The idea introduced here enables choosing processing conditions to tailor film morphology characteristics and paves the ground for a deeper understanding of morphology control with the ultimate goal of precise, yet affordable, morphology manipulation for a large spectrum of applications.

  20. Thin-film ternary superconductors

    International Nuclear Information System (INIS)

    Physical properties and preparation methods of thin film ternary superconductors, (mainly molybdenum chalcogenides) are reviewed. Properties discussed include the superconducting critical fields and critical currents, resistivity and the Hall effect. Experimental results at low temperatures, together with electron microscopy data are used to determine magnetic flux pinning mechanisms in films. Flux pinning results, together with an empirical model for pinning, are used to get estimates for possible applications of thin film ternary superconductors where high current densities are needed in the presence of high magnetic fields. The normal state experimental data is used to derive several Fermi surface parameters, e.g. the Fermi velocity and the effective Fermi surface area. (orig.)

  1. Analysis of the diode characteristics of thin film solar cells based on CdTe

    International Nuclear Information System (INIS)

    A physical approach to the optimization of photoelectric processes in thin film multilayer systems has been developed. By means of a simulation of the influence of light-diode characteristics on the efficiency factor, it is concluded that the optimization of the photoelectric processes in ITO/CdS/CdTe/Cu/Au film solar cells is mainly determined by two competing physical mechanisms: an increase in the efficiency of the process of distribution of nonequilibrium charge carriers and a reduction in the efficiency of their generation, as the CdS layer thickness grows

  2. Ultrasensitive organic phototransistors with multispectral response based on thin-film/single-crystal bilayer structures

    Science.gov (United States)

    Pinto, R. M.; Gouveia, W.; Neves, A. I. S.; Alves, H.

    2015-11-01

    We report on highly efficient organic phototransistors (OPTs) based on thin-film/single-crystal planar bilayer junctions between 5,6,11,12-tetraphenyltetracene (rubrene) and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM). The OPTs show good field-effect characteristics in the dark, with high hole-mobility (4-5 cm2 V-1 s-1), low-contact resistance (20 kΩ cm), and low-operating voltage (≤5 V). Excellent sensing capabilities allow for light detection in the 400-750 nm range, with photocurrent/dark current ratio as high as 4 × 104, responsivity on the order of 20 AW-1 at 27 μW cm-2, and an external quantum efficiency of 52 000%. Photocurrent generation is attributed to enhanced electron and hole transfer at the interface between rubrene and PC61BM, and fast response times are observed as a consequence of the high-mobility of the interfaces. The optoelectronic properties exhibited in these OPTs outperform those typically provided by a-Si based devices, enabling future applications where multifunctionality in a single-device is sought.

  3. Ultrasensitive organic phototransistors with multispectral response based on thin-film/single-crystal bilayer structures

    Energy Technology Data Exchange (ETDEWEB)

    Pinto, R. M., E-mail: rpinto@inesc-mn.pt [INESC MN and IN, Rua Alves Redol 9, 1000-029 Lisboa (Portugal); CQFM, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Gouveia, W. [INESC MN and IN, Rua Alves Redol 9, 1000-029 Lisboa (Portugal); Neves, A. I. S. [INESC MN and IN, Rua Alves Redol 9, 1000-029 Lisboa (Portugal); College of Engineering, Mathematics and Physical Sciences, University of Exeter, EX4 4QL Exeter (United Kingdom); Alves, H. [INESC MN and IN, Rua Alves Redol 9, 1000-029 Lisboa (Portugal); CICECO, Physics Department, Universidade de Aveiro, 3810-193 Aveiro (Portugal)

    2015-11-30

    We report on highly efficient organic phototransistors (OPTs) based on thin-film/single-crystal planar bilayer junctions between 5,6,11,12-tetraphenyltetracene (rubrene) and [6,6]-phenyl-C{sub 61}-butyric acid methyl ester (PC{sub 61}BM). The OPTs show good field-effect characteristics in the dark, with high hole-mobility (4–5 cm{sup 2} V{sup −1} s{sup −1}), low-contact resistance (20 kΩ cm), and low-operating voltage (≤5 V). Excellent sensing capabilities allow for light detection in the 400–750 nm range, with photocurrent/dark current ratio as high as 4 × 10{sup 4}, responsivity on the order of 20 AW{sup −1} at 27 μW cm{sup −2}, and an external quantum efficiency of 52 000%. Photocurrent generation is attributed to enhanced electron and hole transfer at the interface between rubrene and PC{sub 61}BM, and fast response times are observed as a consequence of the high-mobility of the interfaces. The optoelectronic properties exhibited in these OPTs outperform those typically provided by a-Si based devices, enabling future applications where multifunctionality in a single-device is sought.

  4. High-performance metal–semiconductor–metal UV photodetector based on spray deposited ZnO thin films

    International Nuclear Information System (INIS)

    Highlights: • ZnO based MSM UV photodetector by economical chemical spray pyrolysis technique. • Effect of substrate temperature on properties of ZnO based MSM UV photodetector. • Photoresponse mechanism by optical switching property of ZnO thin film photodetectors. - Abstract: Zinc oxide (ZnO) based metal–semiconductor–metal (MSM) ultraviolet photodetectors at different substrate temperatures were fabricated on glass substrates by economical chemical spray pyrolysis technique and its UV photoresponsivity was measured at room temperature. The samples were characterized with respect to their structural, morphological, and optical properties using various methods such as X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–Vis spectroscopy, transmittance, reflectance etc. The synthesized ZnO thin films were c-axis oriented with hexagonal crystal structure as confirmed from XRD. All deposited films were specular and show high transmittance (∼85%) in visible region with steep fall off at 375 nm. The photoconductive MSM UV photodetector showed relatively high photocurrent (1.3 mA) and fast switching. ZnO thin films exhibited relatively high photoresponsivity (788 A/W) with cut of wavelength ∼375 nm signifying their application as UV detector

  5. Bimodal swelling responses in microgel thin films.

    Science.gov (United States)

    Sorrell, Courtney D; Lyon, L Andrew

    2007-04-26

    A series of studies on microgel thin films is described, wherein quartz crystal microgravimetry (QCM), surface plasmon resonance (SPR), and atomic force microscopy (AFM) have been used to probe the properties of microstructured polymer thin films as a function of film architecture and solution pH. Thin films composed of pNIPAm-co-AAc microgels were constructed by using spin-coating layer-by-layer (scLbL) assembly with poly(allylamine hydrochloride) (PAH) as a polycationic "glue". Our findings suggest that the interaction between the negatively charged microgels and the positively charged PAH has a significant impact on the pH responsivity of the film. These effects are observable in both the optical and mechanical behaviors of the films. The most significant changes in behavior are observed when the motional resistance of a quartz oscillator is monitored via QCM experiments. Slight changes to the film architecture and alternating the pH of the environment significantly changes the QCM and SPR responses, suggesting a pH-dependent swelling that is dependent on both particle swelling and polyelectrolyte de-complexation. Together, these studies allow for a deeper understanding of the morphological changes that take place in environmentally responsive microgel-based thin films. PMID:17407344

  6. Development of Bismuth-based Lead-free Piezoelectric Materials: Thin Film Piezoelectric Materials via PVD and CSD Routes

    Science.gov (United States)

    Jeon, Yu Hong

    Piezoelectric materials have been widely used in electromechanical actuators, sensors, and ultrasonic transducers. Among these materials, lead zirconate titanate Pb(Zr1-xTix)O3 (PZT) has been primarily investigated due to its excellent piezoelectric properties. However, environmental concerns due to the toxicity of PbO have led to investigations into alternative materials systems. Bismuth-based perovskite piezoelectric materials such as (Bi0.5,Na0.5)TiO3 - (Bi0.5K 0.5)TiO3 (BNT - BKT), (Bi0.5,Na0.5 )TiO3 - (Bi0.5K0.5)TiO3 - BaTiO3(BNT - BKT - BT), (Bi0.5K 0.5)TiO3 - Bi(Zn0.5,Ti0.5)O 3 (BKT - BZT), and (Bi0.5,Na0.5)TiO 3 - (Bi0.5K0.5)TiO3 - Bi(Mg 0.5,Ti0.5)O3 (BNT - BKT - BMgT) have been explored as potential alternatives to PZT. These materials systems have been extensively studied in bulk ceramic form, however many of the ultimate applications will be in thin film embodiments (i.e., microelectromechanical systems). For this reason, in this thesis these lead-free piezoelectrics are synthesized in thin film form to understand the structure-property-processing relationships and their impact on the ultimate device response. Fabrication of high quality of 0.95BKT - 0.05BZT thin films on platinized silicon substrates was attempted by pulsed laser deposition. Due to cation volatility, deposition parameters such as substrate temperature, deposition pressure, and target-substrate distance, as well as target overdoping were explored to achieve phase pure materials. This route led to high dielectric loss, indicative of poor ferroelectric behavior. This was likely a result of the poor thin film morphology observed in films deposited via this method. Subsequently, 0.8BNT - 0.2BKT, 85BNT - 10BKT - 5BT, and 72.5BNT - 22.5BKT - 5BMgT (near morphotropic phase boundary composition) were synthesized via chemical solution deposition. To compensate the loss of A-site cations, overdoped precursor solutions were prepared. Crystallization after each spin cast layer were required to

  7. Investigation of gamma-ray sensitivity of neutron detectors based on thin converter films

    CERN Document Server

    Khaplanov, Anton; Buffet, Jean-Claude; Clergeau, Jean-Francois; Correa, Jonathan; van Esch, Patrick; Ferraton, Mathieu; Guerard, Bruno; Hall-Wilton, Richard

    2013-01-01

    Currently, many detector technologies for thermal neutron detection are in development in order to lower the demand for the rare 3He gas. Gas detectors with solid thin film neutron converters readout by gas proportional counter method have been proposed as an appropriate choice for applications where large area coverage is necessary. In this paper, we investigate the probability for gamma-rays to generate a false count in a neutron measurement. Simulated results are compared to measurement with a 10B thin film prototype and a 3He detector. It is demonstrated that equal gamma-ray rejection to that of 3He tubes is achieved with the new technology. The arguments and results presented here are also applicable to gas detectors with converters other than solid 10B layers, such as 6Li layers and 10BF3 gas.

  8. Performance Evaluation of ZnO based Rare Earth Element Doped Thin Films

    Directory of Open Access Journals (Sweden)

    Manish Sharma

    2013-10-01

    Full Text Available In DMS materials, a small fraction of a host semiconductor cation is substituted by magnetic ions. We chose as semiconducting host the transparent ZnO, with a bandgap of 3.3 eV at room temperature. Studies on ZnO doped with 3d transition metals indicated only small magnetic moments. The more recent results for Gd in GaN, indicating high magnetic moments, motivated us to investigate ZnO thin films doped with rare earth (RE metal ions. For the 3d transition metals, the 3d electrons are exterior and delocalized; leading to strong direct exchange interactions and high Curie temperatures, but often the orbital momentum is zero, leading to small total magnetic moments per atom. In RE metals, the 4f electrons are localized, exchange interactions are indirect, via 5d or 6s conduction electrons, but the high orbital momentum is leading to high total magnetic moments per atom, like 3.27μB for Nd. The Curie point for Nd is 19 K. In this paper we present the results of our study on ZnO films doped with Nd. Hall measurements are performed to investigate the electrical properties of films. Here we prepared and investigated ZnO films doped with different concentration of Nd. The films are grown on a-plane Al2O3 or SiO2 substrates. Hall investigations of electrical properties revealed the presence of a degenerate, highly conducting, film–substrate interface layer for the films grown on Al2O3; such an effect can be avoided, for example, by using SiO2 substrates. Magnetotransport measurements indicated no anomalous Hall effect, but a pronounced negative magneto resistance ratio that can be interpreted as a paramagnetic response of the system to the applied magnetic field. We would like to proceed with the surface sensitive techniques for investigating magnetic properties of ZnO:RE thin films.

  9. Flexible gastrointestinal motility pressure sensors based on aluminum thin-film strain-gauge arrays

    OpenAIRE

    Silva, Luís Rebelo; Sousa, Paulo J.; L.M. Gonçalves; Minas, Graça

    2015-01-01

    This paper reports on an innovative approach to measuring intraluminal pressure in the upper gastrointestinal (GI) tract, especially monitoring GI motility and peristaltic movements. The proposed approach relies on thin-film aluminum strain gauges deposited on top of a Kapton membrane, which in turn lies on top of an SU-8 diaphragm-like structure. This structure enables the Kapton membrane to bend when pressure is applied, thereby affecting the strain gauges and effectively cha...

  10. Investigation of gamma-ray sensitivity of neutron detectors based on thin converter films

    OpenAIRE

    Khaplanov, Anton; Piscitelli, Francesco; Buffet, Jean-Claude; Clergeau, Jean-Francois; Correa, Jonathan; Van Esch, Patrick; Ferraton, Mathieu; Guerard, Bruno; Hall-Wilton, Richard

    2013-01-01

    Currently, many detector technologies for thermal neutron detection are in development in order to lower the demand for the rare 3He gas. Gas detectors with solid thin film neutron converters readout by gas proportional counter method have been proposed as an appropriate choice for applications where large area coverage is necessary. In this paper, we investigate the probability for gamma-rays to generate a false count in a neutron measurement. Simulated results are compared to measurement wi...

  11. Characterization of Laser Beam Shaping Optics Based on Their Ablation Geometry of Thin Films

    OpenAIRE

    Stefan Rung; Johannes Barth; Ralf Hellmann

    2014-01-01

    Thin film ablation with pulsed nanosecond lasers can benefit from the use of beam shaping optics to transform the Gaussian beam profile with a circular footprint into a Top-Hat beam profile with a rectangular footprint. In general, the quality of the transformed beam profile depends strongly on the beam alignment of the entire laser system. In particular, the adjustment of the beam shaping element is of upmost importance. For an appropriate alignment of the beam shaper, it is generally necess...

  12. Testing of flexible InGaZnO-based thin-film transistors under mechanical strain

    Science.gov (United States)

    Münzenrieder, N. S.; Cherenack, K. H.; Tröster, G.

    2011-08-01

    Thin-film transistors (TFTs) fabricated on flexible plastic substrates are an integral part of future flexible large-area electronic devices like displays and smart textiles. Devices for such applications require stable electrical performance under electrical stress and also during applied mechanical stress induced by bending of the flexible substrate. Mechanical stress can be tensile or compressive strain depending on whether the TFT is located outside or inside of the bending plane. Especially the impact of compressive bending on TFT performance is hard to measure, because the device is covered with the substrate in this case. We present a method which allows us to continuously measure the electrical performance parameters of amorphous Indium-Gallium-Zinc Oxide (a-IGZO) based TFTs exposed to arbitrary compressive and tensile bending radii. To measure the influence of strain on a TFT it is attached and electrically connected to a flexible carrier foil, which afterwards is fastened to two plates in our bending tester. The bending radius can be adjusted by changing the distance between these plates. Thus it is possible to apply bending radii in the range between a totally flat substrate and ≈1 mm, corresponding to a strain of ≈3.5%. The tested bottom-gate TFTs are especially designed for use with our bending tester and fabricated on 50 μm thick flexible Kapton® E polyimide substrates. To show the different application areas of our bending method we characterized our TFTs while they are bent to different tensile and compressive bending radii. These measurements show that the field effect mobilities and threshold voltages of the tested a-IGZO TFTs are nearly, but not absolutely, stable under applied strain, compared to the initial values the mobilities shift by ≈3.5% in the tensile case and ≈-1.5% in the compressive one, at a bending radius of 8 mm. We also measured the influence of repeated bending (2500 cycles over ≈70 h), where a shift of the

  13. High efficiency cadmium telluride and zinc telluride based thin-film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Rohatgi, A.; Sudharsanan, R.; Ringel, S.A.; Chou, H.C. (Georgia Inst. of Tech., Atlanta, GA (United States))

    1992-10-01

    This report describes work to improve the basic understanding of CdTe and ZnTe alloys by growing and characterizing these films along with cell fabrication. The major objective was to develop wide-band-gap (1.6--1.8 eV) material for the top cell, along with compatible window material and transparent ohmic contacts, so that a cascade cell design can be optimized. Front-wall solar cells were fabricated with a glass/SnO{sub 2}/CdS window, where the CdS film is thin to maximize transmission and current. Wide-band-gap absorber films (E{sub g} = 1.75 eV) were grown by molecular beam epitaxy (MBE) and metal-organic chemical vapor deposition (MOCVD) techniques, which provided excellent control for tailoring the film composition and properties. CdZnTe films were grown by both MBE and MOCVD. All the as-grown films were characterized by several techniques (surface photovoltage spectroscopy, Auger electron spectroscopy (AES), and x-ray photoelectron spectroscopy (XPS)) for composition, bulk uniformity, thickness, and film and interface quality. Front-wall-type solar cells were fabricated in collaboration with Ametek Materials Research Laboratory using CdTe and CdZnTe polycrystalline absorber films. The effects of processing on ternary film were studied by AES and XPS coupled with capacitance voltage and current voltage measurements as a function of temperature. Bias-dependent spectral response and electrical measurements were used to test some models in order to identify and quantify dominant loss mechanisms.

  14. Room temperature analysis of dielectric function of ZnO-based thin film on fused quartz substrate

    Science.gov (United States)

    Kurniawan, Robi; Sutjahja, Inge M.; Winata, Toto; Rusydi, Andrivo; Darma, Yudi

    2015-09-01

    A set of sample consist of pure ZnO and Cu-doped ZnO film were grown on fused-quartz substrates using pulsed laser deposition (PLD) technique. Here, we report room temperature spectroscopic ellipsometry analysis (covering energy range of 0.5 to 6.3 eV) of pure ZnO film and Cu doped ZnO film at 8 in at. %. The thickness of pure ZnO and Cu-doped ZnO film using in this study is about 350 nm. To extract the dielectric function of ZnO thin film, multilayer modeling is performed which takes into account reflections at each interface through Fresnel coefficients. This method based on Drude-Lorentz models that connect with Kramers-Kronig relations. The best fitting of Ψ (amplitude ratio) and Δ (phase difference) taken by SE measurement are obtained reasonably well by mean the universal fitting of three different photon incident angles. The imaginary part of dielectric function (ɛ2) show the broad peak at around 3.3 eV assigned as combination of optical band energy edge with excitonic states. The exitonic states could not be observed clearly in this stage. The evolution of extracted dielectric function is observable by introducing 8% Cu as indicated by decreasing of excitonic intensity. This result indicates the screening of excitonic state. This study will bring us to have a good undestanding for the role of Cu impurities for ZnO thin films.

  15. Studying thin film damping in a micro-beam resonator based on non-classical theories

    Institute of Scientific and Technical Information of China (English)

    Mina Ghanbari; Siamak Hossainpour; Ghader Rezazadeh

    2016-01-01

    In this paper, a mathematical model is presented for studying thin film damping of the surrounding fluid in an in-plane oscillating micro-beam resonator. The proposed model for this study is made up of a clamped-clamped micro-beam bound between two fixed layers. The micro-gap between the micro-beam and fixed layers is filled with air. As classical theories are not properly capable of pre-dicting the size dependence behaviors of the micro-beam, and also behavior of micro-scale fluid media, hence in the presented model, equation of motion governing longitudinal displacement of the micro-beam has been extracted based on non-local elasticity theory. Furthermore, the fluid field has been modeled based on micro-polar theory. These coupled equations have been simplified using Newton-Laplace and continuity equations. After transforming to non-dimensional form and linearizing, the equations have been discretized and solved simultaneously using a Galerkin-based reduced order model. Considering slip boundary conditions and applying a complex frequency approach, the equivalent damping ratio and quality factor of the micro-beam resonator have been obtained. The obtained values for the quality factor have been compared to those based on classical theories. We have shown that applying non-classical theories underestimate the values of the quality factor obtained based on classical theo-ries. The effects of geometrical parameters of the micro-beam and micro-scale fluid field on the quality factor of the res-onator have also been investigated.

  16. Bismuth ferrite based thin films, nanofibers, and field effect transistor devices

    Science.gov (United States)

    Rivera-Beltran, Rut

    In this research an attempt has been made to explore bismuth ferrite thin films with low leakage current and nanofibers with high photoconductivity. Thin films were deposited with pulsed laser deposition (PLD) method. An attempt has been made to develop thin films under different deposition parameters with following target compositions: i) 0.6BiFeO3-0.4(Bi0.5 K0.5)TiO3 (BFO-BKT) and ii) bi-layered 0.88Bi 0.5Na0.5TiO3-0.08Bi0.5K0.5TiO 3-0.04BaTiO3/BiFeO3 (BNT-BKT-BT/BFO). BFO-BKT thin film shows suppressed leakage current by about four orders of magnitude which in turn improve the ferroelectric and dielectric properties of the films. The optimum remnant polarization is 19 muC.cm-2 at the oxygen partial pressure of 300 mtorr. The BNT-BKT-BT/BFO bi-layered thin films exhibited ferroelectric behavior as: Pr = 22.0 muC.cm-2, Ec = 100 kV.cm-1 and epsilonr = 140. The leakage current of bi-layered thin films have been reduced two orders of magnitude compare to un-doped bismuth ferrite. Bismuth ferrite nanofibers were developed by electrospinning technique and its electronic properties such as photoconductivity and field effect transistor performance were investigated extensively. Nanofibers were deposited by electrospinning of sol-gel solution on SiO2/Si substrate at driving voltage of 10 kV followed by heat treatment at 550 °C for 2 hours. The composition analysis through energy dispersive detector and electron energy loss spectroscopy revealed the heterogeneous nature of the composition with Bi rich and Fe deficient regions. X-ray photoelectron spectroscopy results confirmed the combination of Fe3+ and Fe2+ valence state in the fibers. The photoresponse result is almost hundred times higher for a fiber of 40 nm diameter compared to a fiber with 100 nm diameter. This effect is described by a size dependent surface recombination mechanism. A single and multiple BFO nanofibers field effect transistors devices were fabricated and characterized. Bismuth ferrite FET behaves

  17. Thermal annealing of thin PECVD silicon-oxide films for airgap-based optical filters

    Science.gov (United States)

    Ghaderi, M.; de Graaf, G.; Wolffenbuttel, R. F.

    2016-08-01

    This paper investigates the mechanical and optical properties of thin PECVD silicon-oxide layers for optical applications. The different deposition parameters in PECVD provide a promising tool to manipulate and control the film structure. Membranes for use in optical filters typically are of ~λ/4n thickness and should be slightly tensile for remaining flat, thus avoiding scattering. The effect of the thermal budget of the process on the mechanical characteristics of the deposited films was studied. Films with compressive stress ranging from  ‑100 to 0 MPa were deposited. Multiple thermal annealing cycles were applied to wafers and the in situ residual stress and ex situ optical properties were measured. The residual stress in the films was found to be highly temperature dependent. Annealing during the subsequent process steps results in tensile stress from 100 to 300 MPa in sub-micron thick PECVD silicon-oxide films. However, sub-100 nm thick PECVD silicon-oxide layers exhibit a lower dependence on the thermal annealing cycles, resulting in lower stress variations in films after the annealing. It is also shown that the coefficient of thermal expansion, hence the residual stress in layers, varies with the thickness. Finally, several free-standing membranes were fabricated and the results are compared.

  18. Chemical vapor deposition and characterization of polysilanes polymer based thin films and their applications in compound semiconductors and silicon devices

    Science.gov (United States)

    Oulachgar, El Hassane

    As the semiconductors industry is moving toward nanodevices, there is growing need to develop new materials and thin films deposition processes which could enable strict control of the atomic composition and structure of thin film materials in order to achieve precise control on their electrical and optical properties. The accurate control of thin film characteristics will become increasingly important as the miniaturization of semiconductor devices continue. There is no doubt that chemical synthesis of new materials and their self assembly will play a major role in the design and fabrication of next generation semiconductor devices. The objective of this work is to investigate the chemical vapor deposition (CVD) process of thin film using a polymeric precursor as a source material. This process offers many advantages including low deposition cost, hazard free working environment, and most importantly the ability to customize the polymer source material through polymer synthesis and polymer functionalization. The combination between polymer synthesis and CVD process will enable the design of new generation of complex thin film materials with a wide range of improved chemical, mechanical, electrical and optical properties which cannot be easily achieved through conventional CVD processes based on gases and small molecule precursors. In this thesis we mainly focused on polysilanes polymers and more specifically poly(dimethylsilanes). The interest in these polymers is motivated by their distinctive electronic and photonic properties which are attributed to the delocalization of the sigma-electron along the Si-Si backbone chain. These characteristics make polysilane polymers very promising in a broad range of applications as a dielectric, a semiconductor and a conductor. The polymer-based CVD process could be eventually extended to other polymer source materials such as polygermanes, as well as and a variety of other inorganic and hybrid organic-inorganic polymers

  19. Organic photovoltaic cells based on ZnO thin film electrodes.

    Science.gov (United States)

    Ghica, C; Ion, L; Epurescu, G; Nistor, L; Antohe, S; Dinescu, M

    2010-02-01

    Due to its wide band-gap (ca. 3.4 eV), ZnO is a possible candidate material to be used as transparent electrode for a new class of photovoltaic (PV) cells. Also, an increased interest for the photovoltaic properties of several organic monomers and polymers (merocyanines, phthalocyanines and porphyrins) was noticed, because of their high optical absorption in the visible region of the spectrum allowing them to be used as potential inexpensive materials for solar cells. Preparation and properties of CuPc (copper phthalocyanine) based photovoltaic cells using ZnO thin films as transparent conductor electrodes are presented in this paper. ZnO layers are grown by pulsed laser deposition, while the organic layers are obtained by thermal evaporation. Structural characterization is performed by electron microscopy. Optical and transport properties of the mutilayered structures are obtained by electrical and spectro-photometric measurements. The influence of the ZnO-polymer interface on the external quantum efficiency (EQE) of the photovoltaic cell is clearly evidenced by our measurements.

  20. High-photosensitivity polymer thin-film transistors based on poly(3-hexylthiophene)

    Institute of Scientific and Technical Information of China (English)

    Liu Yu-Rong; Lai Pei-Tao; Yao Ruo-He

    2012-01-01

    Polymer thin-film transistors (PTFTs) based on poly(3-hexylthiophene) are fabricated by the spin-coating process,and their photo-sensing characteristics are investigated under steadly-state visible-light illumination.The photosensitivity of the device is strongly modulated by gate voltage under various illuminations.When the device is in the subthreshold operating mode,a significant increase in its drain current is observed with a maximum photosensitivity of 1.7×103 at an illumination intensity of 1200 lx,and even with a relatively high photosensitivity of 611 at a low illumination intensity of 100 lx.However,when the device is in the on-state operating mode,the photosensitivity is very low:only 1.88 at an illumination intensity of 1200 lx for a gate voltage of --20 V and a drain voltage of -20 V.The results indicate that the devices could be used as photo-detectors or sensors in the range of visible light.The modulation mechanism of the photosensitivity in the PTFT is discussed in detail.

  1. Inverter Circuits Using ZnO Nanoparticle Based Thin-Film Transistors for Flexible Electronic Applications

    Directory of Open Access Journals (Sweden)

    Fábio F. Vidor

    2016-08-01

    Full Text Available Innovative systems exploring the flexibility and the transparency of modern semiconducting materials are being widely researched by the scientific community and by several companies. For a low-cost production and large surface area applications, thin-film transistors (TFTs are the key elements driving the system currents. In order to maintain a cost efficient integration process, solution based materials are used as they show an outstanding tradeoff between cost and system complexity. In this paper, we discuss the integration process of ZnO nanoparticle TFTs using a high-k resin as gate dielectric. The performance in dependence on the transistor structure has been investigated, and inverted staggered setups depict an improved performance over the coplanar device increasing both the field-effect mobility and the ION/IOFF ratio. Aiming at the evaluation of the TFT characteristics for digital circuit applications, inverter circuits using a load TFT in the pull-up network and an active TFT in the pull-down network were integrated. The inverters show reasonable switching characteristics and V/V gains. Conjointly, the influence of the geometry ratio and the supply voltage on the devices have been analyzed. Moreover, as all integration steps are suitable to polymeric templates, the fabrication process is fully compatible to flexible substrates.

  2. On-chip cooling by superlattice-based thin-film thermoelectrics

    Science.gov (United States)

    Chowdhury, Ihtesham; Prasher, Ravi; Lofgreen, Kelly; Chrysler, Gregory; Narasimhan, Sridhar; Mahajan, Ravi; Koester, David; Alley, Randall; Venkatasubramanian, Rama

    2009-04-01

    There is a significant need for site-specific and on-demand cooling in electronic, optoelectronic and bioanalytical devices, where cooling is currently achieved by the use of bulky and/or over-designed system-level solutions. Thermoelectric devices can address these limitations while also enabling energy-efficient solutions, and significant progress has been made in the development of nanostructured thermoelectric materials with enhanced figures-of-merit. However, fully functional practical thermoelectric coolers have not been made from these nanomaterials due to the enormous difficulties in integrating nanoscale materials into microscale devices and packaged macroscale systems. Here, we show the integration of thermoelectric coolers fabricated from nanostructured Bi2Te3-based thin-film superlattices into state-of-the-art electronic packages. We report cooling of as much as 15 °C at the targeted region on a silicon chip with a high (~1,300 W cm-2) heat flux. This is the first demonstration of viable chip-scale refrigeration technology and has the potential to enable a wide range of currently thermally limited applications.

  3. Quantitative determination of element distributions in silicon based thin film solar cells using SNMS.

    Science.gov (United States)

    Gastel, M; Breuer, U; Holzbrecher, H; Becker, J S; Dietze, H J; Kubon, M; Wagner, H

    1995-10-01

    The determination of elemental distributions in thin film solar cells based on amorphous silicon using electron beam SNMS is possible by quantifying the measured ion intensities. The relative sensitivity factors (RSFs) for all elements measured have to be known. The RSFs have been determined experimentally using implantation and bulk standards with known concentrations of the interesting elements. The measured RSFs have been compared with calculated RSFs. The model used for the calculation of the RSFs takes into account the probability for electron impact ionization and the dwell time of the neutrals inside the postionization region. The comparison between measured and calculated RSF shows, that this model is capable to explain the RSFs for most elements. Differences between calculated and measured values can be explained by the formation of hydride and fluoride molecules (in case of H and F) and influences of the angular distribution of the sputtered neutrals in case of Al. The experimentally determined RSFs have been used for a quantification of depth profiles of the i-, buffer-, p- and front contact layers of a-Si solar cells. PMID:15048522

  4. Effective contact resistance of zinc-tin oxide-based thin film transistors.

    Science.gov (United States)

    Kang, Youjin; Han, Dongsuk; Park, Jaehyung; Shin, Sora; Choi, Duckkyun; Park, Jongwan

    2014-11-01

    We investigated different source/drain (S/D) electrode materials in thin-film transistors (TFTs) based on amorphous zinc-tin oxide (ZTO) semiconductors. The transfer length, channel conductance, and effective contact resistance between the S/D electrodes and the a-ZTO channel layer were examined. Total ON resistance (R(T)), transfer length (L(T)) and effective contact resistance (R(c-eff)) were extracted by the well-known transmission-line method (TLM) using a series of TFTs with different channel lengths. When the width of ZTO channel layer was fixed as 50 μm, the lengths were varying from 10 to 50 μm. The channel layer and S/D electrode were defined by lift-off process and for the S/D electrodes, indium-tin oxide (ITO), Cu, and Mo were used. The resistivity and work function values of electrode materials were considered when selected as candidates for S/D electrodes of ZTO-TFTs. The results showed that the ZTO-TFTs with Mo S/D electrodes had the lowest effective contact resistance indicating that ZTO-TFTs with Mo electrodes have better electrical performance compared to others. PMID:25958489

  5. Studies on electrochromic smart windows based on titanium doped WO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Karuppasamy, A. [Semiconductor Laboratory, Department of Physics, Indian Institute of Technology Madras, Chennai - 600036 (India)], E-mail: ksamy@physics.iitm.ac.in; Subrahmanyam, A. [Semiconductor Laboratory, Department of Physics, Indian Institute of Technology Madras, Chennai - 600036 (India)

    2007-12-03

    Titanium doped tungsten oxide thin films have been deposited by co-sputtering metallic titanium and tungsten in the presence of argon and oxygen. The oxygen chamber pressure was varied in the range 1 x 10{sup -3}-4 x 10{sup -3} mbar keeping the sputtering power of titanium and tungsten constant at 2 W/cm{sup 2} and 3 W/cm{sup 2} respectively. The effect of oxygen chamber pressure on the electrochromic (EC) properties of titanium doped WO{sub 3} has been investigated in three steps. First, the material properties of EC film were investigated by XRD, SEM, and UV-Vis spectrophotometer; the thickness and the optical constants were estimated from the reflectance measurements. Second, the electrochromic behavior of the EC films was characterized by cyclic voltammetry (CV) using 1.0 M HCl as electrolyte. The optical modulation ({delta}T) and coloration efficiency (CE) of the titanium doped tungsten oxide thin film deposited at an O{sub 2} pressure of 4 x 10{sup -3} mbar was found to be better with typical values of {delta}T = 70% and CE = 66 cm{sup 2}/C (at {lambda} = 550 nm). Finally, EC devices consisting of five layers (Glass/ITO/Ti:WO{sub 3}/Ta{sub 2}O{sub 5}/NiO/ITO) have been fabricated and tested.

  6. Studies on electrochromic smart windows based on titanium doped WO3 thin films

    International Nuclear Information System (INIS)

    Titanium doped tungsten oxide thin films have been deposited by co-sputtering metallic titanium and tungsten in the presence of argon and oxygen. The oxygen chamber pressure was varied in the range 1 x 10-3-4 x 10-3 mbar keeping the sputtering power of titanium and tungsten constant at 2 W/cm2 and 3 W/cm2 respectively. The effect of oxygen chamber pressure on the electrochromic (EC) properties of titanium doped WO3 has been investigated in three steps. First, the material properties of EC film were investigated by XRD, SEM, and UV-Vis spectrophotometer; the thickness and the optical constants were estimated from the reflectance measurements. Second, the electrochromic behavior of the EC films was characterized by cyclic voltammetry (CV) using 1.0 M HCl as electrolyte. The optical modulation (ΔT) and coloration efficiency (CE) of the titanium doped tungsten oxide thin film deposited at an O2 pressure of 4 x 10-3 mbar was found to be better with typical values of ΔT = 70% and CE = 66 cm2/C (at λ = 550 nm). Finally, EC devices consisting of five layers (Glass/ITO/Ti:WO3/Ta2O5/NiO/ITO) have been fabricated and tested

  7. Rupture Limit of Thin Moving Films

    Science.gov (United States)

    Padrino, Juan C.; Joseph, Daniel D.; Kim, Hyungjun

    2010-11-01

    The rupture of a thin film in another fluid is studied including the effects of disjoining pressure. The study considers the linear stability of a moving viscous film in a motionless inviscid fluid and of a stagnant viscous film in a motionless viscous fluid. These are analyzed by means of the Navier--Stokes equations and the dissipation approximation based on potential flow. Results reveal that the dissipation method provides a good approximation for the case of a moving film, whereas its predictions are off the mark for the stagnant film case. The thickness of the gap at the trough of Kelvin-Helmholtz waves locates the formation of holes. The wavelength at final collapse is determined by the length of waves at the trough of the corrugated film. The disjoining pressure effects cause very fast break-up for very thin films. These effects influence the cutoff wavenumber. In the limit of small gaps on this corrugated film, the Reynolds and Weber numbers tend to zero with the gap size, the Ohnesorge number increases like the reciprocal of the square root and the Hamaker number like the reciprocal of the square of the gap. The motion of the film does not enter at the point of formation of holes. Moreover, for the most unstable wave, the ratio of the wavelength to film thickness is found to decrease with decreasing film thickness.

  8. Steady heat conduction-based thermal conductivity measurement of single walled carbon nanotubes thin film using a micropipette thermal sensor

    Science.gov (United States)

    Shrestha, R.; Lee, K. M.; Chang, W. S.; Kim, D. S.; Rhee, G. H.; Choi, T. Y.

    2013-03-01

    In this paper, we describe the thermal conductivity measurement of single-walled carbon nanotubes thin film using a laser point source-based steady state heat conduction method. A high precision micropipette thermal sensor fabricated with a sensing tip size varying from 2 μm to 5 μm and capable of measuring thermal fluctuation with resolution of ±0.01 K was used to measure the temperature gradient across the suspended carbon nanotubes (CNT) film with a thickness of 100 nm. We used a steady heat conduction model to correlate the temperature gradient to the thermal conductivity of the film. We measured the average thermal conductivity of CNT film as 74.3 ± 7.9 W m-1 K-1 at room temperature.

  9. Steady heat conduction-based thermal conductivity measurement of single walled carbon nanotubes thin film using a micropipette thermal sensor

    OpenAIRE

    R. Shrestha; Lee, K. M.; Chang, W. S.; Kim, D. S.; Rhee, G H; Choi, T. Y.

    2013-01-01

    In this paper, we describe the thermal conductivity measurement of single-walled carbon nanotubes thin film using a laser point source-based steady state heat conduction method. A high precision micropipette thermal sensor fabricated with a sensing tip size varying from 2 μm to 5 μm and capable of measuring thermal fluctuation with resolution of ±0.01 K was used to measure the temperature gradient across the suspended carbon nanotubes (CNT) film with a thickness of 100 nm. We used a steady he...

  10. Birefringent non-polarizing thin film design

    Institute of Scientific and Technical Information of China (English)

    QI; Hongji; HONG; Ruijin; HE; Hongbo; SHAO; Jianda; FAN; Zh

    2005-01-01

    In this paper, 2×2 characteristic matrices of uniaxially anisotropic thin film for extraordinary and ordinary wave are deduced at oblique incidence. Furthermore, the reflectance and transmittance of thin films are calculated separately for two polarizations, which provide a new concept for designing non-polarizing thin films at oblique incidence. Besides, using the multilayer birefringent thin films, non-polarizing designs, such as beam splitter thin film at single wavelength, edge filter and antireflection thin film over visible spectral region are obtained at oblique incidence.

  11. Thin film transistors gas sensors based on reduced graphene oxide poly(3-hexylthiophene) bilayer film for nitrogen dioxide detection

    Science.gov (United States)

    Xie, Tao; Xie, Guangzhong; Zhou, Yong; Huang, Junlong; Wu, Mei; Jiang, Yadong; Tai, Huiling

    2014-10-01

    Reduced graphene oxide (RGO)/poly(3-hexylthiophene) (P3HT) bilayer films were firstly utilized as active layers in OTFT gas sensors for nitrogen dioxide (NO2) detection. The OTFT with RGO/P3HT bilayer film exhibited the typical transistor characteristics and better gas sensing properties at room temperature. The electrical parameters of OTFTs based on pure P3HT film and RGO/P3HT bilayer film were calculated. The threshold voltage of OTFT was positively shifted due to the high concentration carriers in RGO. The sensing properties of the sensor with RGO/P3HT bilayer film were also investigated. Moreover, the sensing mechanism was analyzed as well.

  12. Delafossite CuFeO2 thin films electrochemically grown from a DMSO based solution

    International Nuclear Information System (INIS)

    Highlights: • A detailed electrochemical study about the electrodeposition of CuFeO2 from DMSO solution is presented. • The use of a precise quantity of chloride ion as complexing agent is decisive in order to obtain stoichiometric compounds (Cu:Fe ratio 1:1). • As-grown compounds were amorphous. Thus, a thermal treatment was required in order to obtain crystalline CuFeO2 with delafossite structure. • The formation of CuFeO2 was confirmed by XRD and XPS analyses. • Through optical measurements, four absorption in different spectrum regions were characterized: A IR absorption (Eg(IR) = 1.64 eV), two visible absorptions (Egdir(vis) = 2.35 eV, and Egind(vis) = 2.03 eV) and an UV absorption (Egind(UV) = 3.37 eV). - Abstract: This study shows the results obtained in the direct electrodeposition of CuFeO2 thin films from a DMSO based solution. First, a detailed electrochemical study was carried out in order to determinate the best condition for the CuFeO2 electrodeposition. The films were obtained potentiostatically from a 0.01 M CuCl2 + 0.005 M Fe(ClO4)3 + 0.1 M LiClO4 solution in the presence of molecular oxygen at 50 °C onto FTO/glass substrates. In all cases, the time of electrodeposition was 1000 s. The grown films presented a yellow-reddish color and exhibit an homogeneous aspect. Analyses of composition carried out through EDS, shown that a stoichiometric composition (atomic relation Cu:Fe = 1:1) is obtained at a potential of –0.6 V. However, as-grown films analyzed through XRD experiences did not evidence the presence of CuFeO2 compound presumably because it is amorphous. An annealing treatment at 650° C for 30 minutes in an argon atmosphere was necessary to transform the solid phase of the as grown films in crystalline CuFeO2. Furthermore, the presence of CuFeO2 has been confirmed through XPS analyses. UV-vis analyzes shown a ladder-like appearance due to the presence of several absorption edges from the IR to the UV spectrum region. The most

  13. Fabrication of CdS/CdTe-Based Thin Film Solar Cells Using an Electrochemical Technique

    Directory of Open Access Journals (Sweden)

    I. M. Dharmadasa

    2014-06-01

    Full Text Available Thin film solar cells based on cadmium telluride (CdTe are complex devices which have great potential for achieving high conversion efficiencies. Lack of understanding in materials issues and device physics slows down the rapid progress of these devices. This paper combines relevant results from the literature with new results from a research programme based on electro-plated CdS and CdTe. A wide range of analytical techniques was used to investigate the materials and device structures. It has been experimentally found that n-, i- and p-type CdTe can be grown easily by electroplating. These material layers consist of nano- and micro-rod type or columnar type grains, growing normal to the substrate. Stoichiometric materials exhibit the highest crystallinity and resistivity, and layers grown closer to these conditions show n → p or p → n conversion upon heat treatment. The general trend of CdCl2 treatment is to gradually change the CdTe material’s n-type electrical property towards i-type or p-type conduction. This work also identifies a rapid structural transition of CdTe layer at 385 ± 5 °C and a slow structural transition at higher temperatures when annealed or grown at high temperature. The second transition occurs after 430 °C and requires more work to understand this gradual transition. This work also identifies the existence of two different solar cell configurations for CdS/CdTe which creates a complex situation. Finally, the paper presents the way forward with next generation CdTe-based solar cells utilising low-cost materials in their columnar nature in graded bandgap structures. These devices could absorb UV, visible and IR radiation from the solar spectrum and combine impact ionisation and impurity photovoltaic (PV effect as well as making use of IR photons from the surroundings when fully optimised.

  14. Measurement of serum prostate cancer markers using a nanopore thin film based optofluidic chip.

    Science.gov (United States)

    Alzghoul, Salah; Hailat, Mohammad; Zivanovic, Sandra; Que, Long; Shah, Girish V

    2016-03-15

    Currently used cancer marker for prostate adenocarcinoma (PC), serum prostate-specific antigen (PSA), greatly overestimates PC population. Patients with high PSA levels have to undergo unnecessary but physically painful and expensive procedure such as prostate biopsies repeatedly. The reliability of PC test can be greatly increased by finding a protein that is secreted selectively by malignant, but not normal, prostate cells. A recently discovered novel protein, referred as neuroendocrine marker (NEM), is secreted only by malignant prostate cells and released in blood circulation. Although NEM seems to be significantly more reliable based on the data obtained from a limited cohort, currently available NEM ELISA is not suitable for undertaking a large study. Therefore, the goal of the present study was to develop an alternative, label-free assay system that can reliably measure NEM and PSA in patient samples. Herein an optofluidic chip that can reliably detect PSA as well as NEM in patient samples has been developed. The optofluidic chip, which consists of arrayed nanopore-based sensors fabricated from anodic aluminum oxide (AAO) thin film, offers improved sensitivity upon the optimization of the concentration of the detector antibodies immobilized on the sensor surface. The results demonstrate that the chip is reliable, extremely sensitive and requires just 1 µl of patient serum (or even less) to measure PSA and NEM even in a non-cancer individual. Compared with the traditional ELISA for PSA, the nanopore-based sensor assay is 50-100 fold more sensitive, and offers many advantages such as elimination of labeled antigen, need for sophisticated equipment and highly trained individuals. These advantages, along with the low cost, should make the technology suitable for point-of-care application to screen elderly male populations for PC and to monitor the progress of patients undergoing PC treatment. PMID:26457734

  15. Assessing the degradation mechanisms and current limitation design rules of SICR-based thin-film resistors in integrated circuits

    OpenAIRE

    Li, Yuan; Donnet, David; Grzegorczyk, Andrzej; Cavelaars, Jan; Kuper, Fred

    2010-01-01

    The degradation of SiCr-based thin-film resistors under current and temperature stress and the Joule heating in the resistors are experimentally investigated to set current limitation design rules. Degradation mechanisms, the failure modes, and the impact of the stress test on Temperature Coefficient of Resistance (TCR), are studied with the use of various test structures stressed under different conditions (temperature, current density and direction), followed by optical inspections, Infra-R...

  16. Fluoride Selective Optical Sensor Based on Aluminum(III)-Octaethylporphyrin in Thin Polymeric Film: Further Characterization and Practical Application

    OpenAIRE

    Badr, Ibrahim H. A.; Meyerhoff, Mark E.

    2005-01-01

    More detailed analytical studies of a new fluoride selective optical sensor based on the use of aluminum(III)-octaethylporphyrin and a lipophilic pH indicator (4′,5′-dibromofluorescein octadecyl ester; ETH-7075) within a thin plasticized poly(vinyl chloride) film are reported. The sensor exhibits extraordinary optical selectivity for fluoride over a wide range of other anions, including anions with far more positive free energies of hydration (e.g., perchlorate, thiocyanate, nitrate, etc.). U...

  17. Thin-film forces in pseudoemulsion films

    Energy Technology Data Exchange (ETDEWEB)

    Bergeron, V.; Radke, C.J. [California Univ., Berkeley, CA (United States). Dept. of Chemical Engineering]|[Lawrence Berkeley Lab., CA (United States)

    1991-06-01

    Use of foam for enhanced oil recovery (EOR) has shown recent success in steam-flooding field applications. Foam can also provide an effective barrier against gas coning in thin oil zones. Both of these applications stem from the unique mobility-control properties a stable foam possesses when it exists in porous media. Unfortunately, oil has a major destabilizing effect on foam. Therefore, it is important for EOR applications to understand how oil destroys foam. Studies all indicate that stabilization of the pseudoemulsion film is critical to maintain foam stability in the presence of oil. Hence, to aid in design of surfactant formulations for foam insensitivity to oil the authors pursue direct measurement of the thin-film or disjoining forces that stabilize pseudoemulsion films. Experimental procedures and preliminary results are described.

  18. Non-conventional photocathodes based on Cu thin films deposited on Y substrate by sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Perrone, A. [Department of Mathematics and Physics “E. De Giorgi”, University of Salento, 73100 Lecce (Italy); National Institute of Nuclear Physics and University of Salento, 73100 Lecce (Italy); D’Elia, M. [Department of Mathematics and Physics “E. De Giorgi”, University of Salento, 73100 Lecce (Italy); Gontad, F., E-mail: francisco.gontad@le.infn.it [Department of Mathematics and Physics “E. De Giorgi”, University of Salento, 73100 Lecce (Italy); National Institute of Nuclear Physics and University of Salento, 73100 Lecce (Italy); Di Giulio, M.; Maruccio, G. [Department of Mathematics and Physics “E. De Giorgi”, University of Salento, 73100 Lecce (Italy); Cola, A. [National Council Research, Institute for Microelectronics and Microsystems, 73100 Lecce (Italy); Stankova, N.E. [Institute of Electronics, Bulgarian Academy of Sciences, 1784 Sofia (Bulgaria); Kovacheva, D.G. [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); Broitman, E. [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping (Sweden)

    2014-07-01

    Copper (Cu) thin films were deposited on yttrium (Y) substrate by sputtering. During the deposition, a small central area of the Y substrate was shielded to avoid the film deposition and was successively used to study its photoemissive properties. This configuration has two advantages: the cathode presents (i) the quantum efficiency and the work function of Y and (ii) high electrical compatibility when inserted into the conventional radio-frequency gun built with Cu bulk. The photocathode was investigated by scanning electron microscopy to determine surface morphology. X-ray diffraction and atomic force microscopy studies were performed to compare the structure and surface properties of the deposited film. The measured electrical resistivity value of the Cu film was similar to that of high purity Cu bulk. Film to substrate adhesion was also evaluated using the Daimler–Benz Rockwell-C adhesion test method. Finally, the photoelectron performance in terms of quantum efficiency was obtained in a high vacuum photodiode cell before and after laser cleaning procedures. A comparison with the results obtained with a twin sample prepared by pulsed laser deposition is presented and discussed.

  19. Hole mobility modulation of solution-processed nickel oxide thin-film transistor based on high-k dielectric

    Science.gov (United States)

    Liu, Ao; Liu, Guoxia; Zhu, Huihui; Shin, Byoungchul; Fortunato, Elvira; Martins, Rodrigo; Shan, Fukai

    2016-06-01

    Solution-processed p-type oxide semiconductors have recently attracted increasing interests for the applications in low-cost optoelectronic devices and low-power consumption complementary metal-oxide-semiconductor circuits. In this work, p-type nickel oxide (NiOx) thin films were prepared using low-temperature solution process and integrated as the channel layer in thin-film transistors (TFTs). The electrical properties of NiOx TFTs, together with the characteristics of NiOx thin films, were systematically investigated as a function of annealing temperature. By introducing aqueous high-k aluminum oxide (Al2O3) gate dielectric, the electrical performance of NiOx TFT was improved significantly compared with those based on SiO2 dielectric. Particularly, the hole mobility was found to be 60 times enhancement, quantitatively from 0.07 to 4.4 cm2/V s, which is mainly beneficial from the high areal capacitance of the Al2O3 dielectric and high-quality NiOx/Al2O3 interface. This simple solution-based method for producing p-type oxide TFTs is promising for next-generation oxide-based electronic applications.

  20. Advances in thin-film solar cells

    CERN Document Server

    Dharmadasa, I M

    2012-01-01

    This book concentrates on the latest developments in our understanding of solid-state device physics. The material presented is mainly experimental and based on CdTe thin-film solar cells. It extends these new findings to CIGS thin-film solar cells and presents a new device design based on graded bandgap multilayer solar cells. This design has been experimentally tested using the well-researched GaAs/AlGaAs system and initial devices have shown impressive device parameters. These devices are capable of absorbing all radiation (UV, visible, and infra-red) within the solar spectrum and combines

  1. Sol-Gel-Based Titania-Silica Thin Film Overlay for Long Period Fiber Grating-Based Biosensors.

    Science.gov (United States)

    Chiavaioli, Francesco; Biswas, Palas; Trono, Cosimo; Jana, Sunirmal; Bandyopadhyay, Somnath; Basumallick, Nandini; Giannetti, Ambra; Tombelli, Sara; Bera, Susanta; Mallick, Aparajita; Baldini, Francesco

    2015-12-15

    An evanescent wave optical fiber biosensor based on titania-silica-coated long period grating (LPG) is presented. The chemical overlay, which increases the refractive index (RI) sensitivity of the sensor, consists of a sol-gel-based titania-silica thin film, deposited along the sensing portion of the fiber by means of the dip-coating technique. Changing both the sol viscosity and the withdrawal speed during the dip-coating made it possible to adjust the thickness of the film overlay, which is a crucial parameter for the sensor performance. After the functionalization of the fiber surface using a methacrylic acid/methacrylate copolymer, an antibody/antigen (IgG/anti-IgG) assay was carried out to assess the performance of sol-gel based titania-silica-coated LPGs as biosensors. The analyte concentration was determined from the wavelength shift at the end of the binding process and from the initial binding rate. This is the first time that a sol-gel based titania-silica-coated LPG is proposed as an effective and feasible label-free biosensor. The specificity of the sensor was validated by performing the same model assay after spiking anti-IgG into human serum. With this structured LPG, detection limits of the order of tens of micrograms per liter (10(-11) M) are attained.

  2. Thin films under chemical stress

    Energy Technology Data Exchange (ETDEWEB)

    1991-01-01

    The goal of work on this project has been develop a set of experimental tools to allow investigators interested in transport, binding, and segregation phenomena in composite thin film structures to study these phenomena in situ. Work to-date has focuses on combining novel spatially-directed optical excitation phenomena, e.g. waveguide eigenmodes in thin dielectric slabs, surface plasmon excitations at metal-dielectric interfaces, with standard spectroscopies to understand dynamic processes in thin films and at interfaces. There have been two main scientific thrusts in the work and an additional technical project. In one thrust we have sought to develop experimental tools which will allow us to understand the chemical and physical changes which take place when thin polymer films are placed under chemical stress. In principle this stress may occur because the film is being swelled by a penetrant entrained in solvent, because interfacial reactions are occurring at one or more boundaries within the film structure, or because some component of the film is responding to an external stimulus (e.g. pH, temperature, electric field, or radiation). However all work to-date has focused on obtaining a clearer understanding penetrant transport phenomena. The other thrust has addressed the kinetics of adsorption of model n-alkanoic acids from organic solvents. Both of these thrusts are important within the context of our long-term goal of understanding the behavior of composite structures, composed of thin organic polymer films interspersed with Langmuir-Blodgett (LB) and self-assembled monolayers. In addition there has been a good deal of work to develop the local technical capability to fabricate grating couplers for optical waveguide excitation. This work, which is subsidiary to the main scientific goals of the project, has been successfully completed and will be detailed as well. 41 refs., 10 figs.

  3. [Improved color purity of green OLED device based on Au thin film].

    Science.gov (United States)

    Zhang, Yan-Fei; Zhao, Su-Ling; Xu, Zheng

    2014-04-01

    Au was used as anode in some kind of organic electroluminescent devices. Sometimes transparent Au electrodes are required, which means that the thickness of Au electrode should be as thin as possible. Therefore, two metals together forming an electrode become a choice. In the present paper, translucent Au/Al layer was inserted to anode side, and OLED device with the structure of ITO/Al (16 nm)/Au (10 nm)/TPD (30 nm)/AlQ (30 nm)/LiF (0.5 nm)/Al was prepared. There is a spectral narrowing phenomenon on the device ITO/TPD (30 nm)/AlQ (30 nm)/LiF (0. 5 nm)/Al, and through analysis and experiment it was found that this phenomenon comes from selective permeability to light of Au thin film rather than the microcavity effect. The device maintains wide viewing angle, without the angular dependence. And the color purity of device with Au thin film is improved. PMID:25007596

  4. Broadband epsilon-near-zero metamaterials based on metal-polymer composite thin films

    Science.gov (United States)

    Pinchuk, Pavlo; Jiang, Ke

    2015-10-01

    Epsilon-near-zero (ENZ) metamaterials are designed to exhibit a near-zero response for the real part of the dielectric permittivity at a given frequency or in a specific frequency range. Typically, this frequency range is relatively small. In this paper, we present an approach to broaden this range by controlling the size of the nanoparticles embedded in a thin film. Noble metal nanoparticles exhibit an external size effect that redshifts the Surface Plasmon Resonance frequency with an increase of the size of the particles. The absorption spectrum of a material can be directly related to its dielectric permittivity via the Kramers-Kronig relations. We use the Kramers-Kronig relations to retrieve the complex effective dielectric permittivity of a composite film, which is designed to exhibit ENZ behavior over a broad frequency range. We synthesize a composite thin film embedded with metal nanoparticles of a broad size distribution. Such a material exhibits a broad SPR, and, in turn, broadband ENZ behavior.

  5. Hybrid organotin and tin oxide-based thin films processed from alkynylorganotins: synthesis, characterization, and gas sensing properties.

    Science.gov (United States)

    Renard, Laetitia; Brötz, Joachim; Fuess, Hartmut; Gurlo, Aleksander; Riedel, Ralf; Toupance, Thierry

    2014-10-01

    Hydrolysis-condensation of bis(triprop-1-ynylstannyl)butylene led to nanostructured bridged polystannoxane films yielding tin dioxide thin layers upon UV-treatment or annealing in air. According to Fourier transform infrared (FTIR) spectroscopy, contact angle measurements, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning electron microscopy (SEM) data, the films were composed of a network of aggregated "pseudo-particles", as calcination at 600 °C is required to form cassiterite nanocrystalline SnO2 particles. In the presence of reductive gases such as H2 and CO, these films gave rise to highly sensitive, reversible, and reproducible responses. The best selectivity toward H2 was reached at 150 °C with the hybrid thin films that do not show any response to CO at 20-200 °C. On the other hand, the SnO2 films prepared at 600 °C are more sensitive to H2 than to CO with best operating temperature in the 300-350 °C range. This organometallic approach provides an entirely new class of gas-sensing materials based on a class II organic-inorganic hybrid layer, along with a new way to include organic functionality in gas sensing metal oxides.

  6. Electrodeposition of In{sub 2}O{sub 3} thin films from a dimethylsulfoxide based electrolytic solution

    Energy Technology Data Exchange (ETDEWEB)

    Henriquez, R.; Munoz, E.; Gomez, H. [Instituto de Quimica, Facultad de Ciencias, Pontificia Universidad Catolica de Valparaiso, Curauma Valparaiso (Chile); Dalchiele, E.A.; Marotti, R.E. [Instituto de Fisica and CINQUIFIMA, Facultad de Ingenieria, Montevideo (Uruguay); Martin, F.; Leinen, D.; Ramos-Barrado, J.R. [Laboratorio de Materiales y Superficie, Departamento de Fisica Aplicada and Ingenieria Quimica, Universidad de Malaga (Spain)

    2013-02-15

    Indium (III) oxide (In{sub 2}O{sub 3}) thin films have been obtained after heat treatment of In(OH){sub 3} precursor layers grown by a potential cycling electrodeposition (PCED) method from a dimethylsulfoxide (DMSO) based electrolytic solution onto fluorine-doped tin oxide (FTO) coated glass substrates. X-ray diffraction (XRD) measurements indicate the formation of a polycrystalline In{sub 2}O{sub 3} phase with a cubic structure. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed a smooth morphology of the In{sub 2}O{sub 3} thin films after an optimized heat treatment had been developed. The surface composition and chemical state of the semiconductor films was established by X-ray photoelectron spectroscopy analysis. The nature of the semiconductor material, flat band potential and donor density were determined from Mott-Schottky plots. This study reveals that the In{sub 2}O{sub 3} films exhibited n-type conductivity with an average donor density of 2.2 x 10{sup 17} cm{sup -3}. The optical characteristics were determined through transmittance spectra. The direct and indirect band gap values obtained are according to the accepted values for the In{sub 2}O{sub 3} films of 2.83 and 3.54 eV for the indirect and direct band gap values. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Thin Films in the Photovoltaic Industry

    International Nuclear Information System (INIS)

    In the past years, the yearly world market growth rate for Photovoltaics was an average of more than 40%, which makes it one of the fastest growing industries at present. Business analysts predict the market volume to increase to 40 billion euros in 2010 and expect rising profit margins and lower prices for consumers at the same time. Today PV is still dominated by wafer based Crystalline Silicon Technology as the 'working horse' in the global market, but thin films are gaining market shares. For 2007 around 12% are expected. The current silicon shortage and high demand has kept prices higher than anticipated from the learning curve experience and has widened the windows of opportunities for thin film solar modules. Current production capacity estimates for thin films vary between 3 and 6 GW in 2010, representing a 20% market share for these technologies. Despite the higher growth rates for thin film technologies compared with the industry average, Thin Film Photovoltaic Technologies are still facing a number of challenges to maintain this growth and increase market shares. The four main topics which were discussed during the workshop were: Potential for cost reduction; Standardization; Recycling; Performance over the lifetime.

  8. Semiconductor-nanocrystal/conjugated polymer thin films

    Science.gov (United States)

    Alivisatos, A. Paul; Dittmer, Janke J.; Huynh, Wendy U.; Milliron, Delia

    2010-08-17

    The invention described herein provides for thin films and methods of making comprising inorganic semiconductor-nanocrystals dispersed in semiconducting-polymers in high loading amounts. The invention also describes photovoltaic devices incorporating the thin films.

  9. Integration of microwave termination based on TaN thin films on ferrite substrates

    Science.gov (United States)

    Zhang, Dainan; Ji, Liang; Kolodzey, James

    2015-10-01

    Integration of microwave discrete devices such as isolators and circulators is highly desired for radar and communication platforms and in particular as components used in transmit and receive (T/R) modules. In those applications, Tantalum nitride (TaN) films are widely used as a surface mounted termination to improve the reliability and performance. In the current work, TaN thin films were directly deposited on polycrystalline ferrite substrate (Ni0.3Zn0.7Fe2O4) to be integrated with isolators or circulators. The deposition conditions were first optimized to obtain suitable sheet resistance and near zero temperature coefficients of resistance (TCR). Next a 50 Ω microwave termination was designed and fabricated using standard photolithography techniques. Broadband measurements show that the terminator has a low voltage standing wave ratio (VSWR) of less than 1.20 in the frequency range of DC-20 GHz. The measured resistance was between 48 and 54 Ω.

  10. Improved electrical stability of CdS thin film transistors through Hydrogen-based thermal treatments

    KAUST Repository

    Salas Villaseñor, Ana L.

    2014-06-01

    Thin film transistors (TFTs) with a bottom-gate configuration were fabricated using a photolithography process with chemically bath deposited (CBD) cadmium sulfide (CdS) films as the active channel. Thermal annealing in hydrogen was used to improve electrical stability and performance of the resulting CdS TFTs. Hydrogen thermal treatments results in significant V T instability (V T shift) improvement while increasing the I on/I off ratio without degrading carrier mobility. It is demonstrated that after annealing V T shift and I on/I off improves from 10 V to 4.6 V and from 105 to 10 9, respectively. Carrier mobility remains in the order of 14.5 cm2 V s-1. The reduced V T shift and performance is attributed to a reduction in oxygen species in the CdS after hydrogen annealing, as evaluated by Fourier transform infrared spectroscopy (FTIR). © 2014 IOP Publishing Ltd.

  11. Synthesis and characterization of VO2-based thermochromic thin films for energy-efficient windows

    OpenAIRE

    Batista, C.; Ribeiro, R. M.; Teixeira, Vasco M. P.

    2011-01-01

    Thermochromic VO2 thin films have successfully been grown on SiO2-coated float glass by reactive DC and pulsed-DC magnetron sputtering. The influence of substitutional doping of V by higher valence cations, such as W, Mo, and Nb, and respective contents on the crystal structure of VO2 is evaluated. Moreover, the effectiveness of each dopant element on the reduction of the intrinsic transition temperature and infrared modulation efficiency of VO2 is discussed. In summary, all the dopant elemen...

  12. A photochromic thin film based on salicylideneaniline derivatives intercalated layered double hydroxide

    Science.gov (United States)

    Wang, Xin Rui; Lu, Jun; Yan, Dongpeng; Wei, Min; Evans, David G.; Duan, Xue

    2010-06-01

    Optically transparent thin films with photochromic properties have been fabricated by means of co-intercalation of azomethine-H anions (AMH) and 1-pentanesulfonate (PS) with different molar ratios into the galleries of a ZnAl layered double hydroxide (LDH). The photochromism of AMH occurred in a 2D confined inorganic matrix has been studied by steady state and transient UV-vis spectroscopy. The AMH anion undergoes an excited-state intramolecular proton transfer from the enol tautomer to trans-keto tautomer after UV excitation, and the relaxed back-isomerization to the ground state of enol tautomer was investigated by transient UV-vis spectroscopy.

  13. Electrochemical Synthesis of a Microporous Conductive Polymer Based on a Metal-Organic Framework Thin Film

    KAUST Repository

    Lu, Chunjing

    2014-05-22

    A new approach to preparing 3D microporous conductive polymer has been demonstrated in the electrochemical synthesis of a porous polyaniline network with the utilization of a MOF thin film supported on a conducting substrate. The prepared porous polyaniline with well-defined uniform micropores of 0.84 nm exhibits a high BET surface area of 986 m2 g−1 and a high electric conductivity of 0.125 S cm−1 when doped with I2, which is superior to existing porous conducting materials of porous MOFs, CMPs, and COFs.

  14. Characterization of Sulfur Bonding in CdS:O Buffer Layers for CdTe-based Thin-Film Solar Cells.

    Science.gov (United States)

    Duncan, Douglas A; Kephart, Jason M; Horsley, Kimberly; Blum, Monika; Mezher, Michelle; Weinhardt, Lothar; Häming, Marc; Wilks, Regan G; Hofmann, Timo; Yang, Wanli; Bär, Marcus; Sampath, Walajabad S; Heske, Clemens

    2015-08-01

    On the basis of a combination of X-ray photoelectron spectroscopy and synchrotron-based X-ray emission spectroscopy, we present a detailed characterization of the chemical structure of CdS:O thin films that can be employed as a substitute for CdS layers in thin-film solar cells. It is possible to analyze the local chemical environment of the probed elements, in particular sulfur, hence allowing insights into the species-specific composition of the films and their surfaces. A detailed quantification of the observed sulfur environments (i.e., sulfide, sulfate, and an intermediate oxide) as a function of oxygen content is presented, allowing a deliberate optimization of CdS:O thin films for their use as alternative buffer layers in thin-film photovoltaic devices.

  15. Mass Transfer in Amperometric Biosensors Based on Nanocomposite Thin Films of Redox Polymers and Oxidoreductases

    Directory of Open Access Journals (Sweden)

    Aleksandr L. Simonian

    2002-03-01

    Full Text Available Mass transfer in nanocomposite hydrogel thin films consisting of alternating layers of an organometallic redox polymer (RP and oxidoreductase enzymes was investigated. Multilayer nanostructures were fabricated on gold surfaces by the deposition of an anionic self-assembled monolayer of 11-mercaptoundecanoic acid, followed by the electrostatic binding of a cationic redox polymer, poly[vinylpyridine Os(bis-bipyridine2Clco-allylamine], and an anionic oxidoreductase. Surface plasmon resonance spectroscopy, Fourier transform infrared external reflection spectroscopy (FTIR-ERS, ellipsometry and electrochemistry were employed to characterize the assembly of these nanocomposite films. Simultaneous SPR/electrochemistry enabled real time observation of the assembly of sensing components, changes in film structure with electrode potential, and the immediate, in situ electrochemical verification of substrate-dependent current upon the addition of enzyme to the multilayer structure. SPR and FTIR-ERS studies also showed no desorption of polymer or enzyme from the nanocomposite structure when stored in aqueous environment occurred over the period of three weeks, suggesting that decreasing in substrate sensitivity were due to loss of enzymatic activity rather than loss of film compounds from the nanostructure.

  16. Preparation of thin vyns films

    International Nuclear Information System (INIS)

    The fabrication of thin films of VYNS resin (copolymer of chloride and vinyl acetate) of superficial density from 3 to 50 μg/cm2 with solutions in cyclohexanone is presented. Study and discussion of some properties compared with formvar film (polyvinyl formals). It appears that both can be used as source supports but formvar films are prepared more easily and more quickly, in addition they withstand higher temperatures. The main quality of VYNS is that they can be easily separated even several days after their preparation

  17. Nanostructured thin films and coatings mechanical properties

    CERN Document Server

    2010-01-01

    The first volume in "The Handbook of Nanostructured Thin Films and Coatings" set, this book concentrates on the mechanical properties, such as hardness, toughness, and adhesion, of thin films and coatings. It discusses processing, properties, and performance and provides a detailed analysis of theories and size effects. The book presents the fundamentals of hard and superhard nanocomposites and heterostructures, assesses fracture toughness and interfacial adhesion strength of thin films and hard nanocomposite coatings, and covers the processing and mechanical properties of hybrid sol-gel-derived nanocomposite coatings. It also uses nanomechanics to optimize coatings for cutting tools and explores various other coatings, such as diamond, metal-containing amorphous carbon nanostructured, and transition metal nitride-based nanolayered multilayer coatings.

  18. Thin-film solar cells. Duennschichtsolarzellen

    Energy Technology Data Exchange (ETDEWEB)

    Bloss, W.H.; Pfisterer, F.; Schock, H.W. (Stuttgart Univ. (Germany, F.R.). Inst. fuer Physikalische Elektronik)

    1990-01-01

    The authors present the state of the art in research and development, technology, production and marketing, and of the prospects of thin-film solar cells. Thin-film solar cells most used at present are based on amorphous silicon and on the compound semiconductors CuInSe{sub 2} and CdTe. Efficiencies in excess 12% have been achieved (14.1% with CuInSe{sub 2}). Stability is the main problem with amorphous silicon. Thin-film solar cells made from compound semiconductors do not have this problem, though their cost-effective series production needs to be shown still. The development potential of the three types mentioned will be ca. 30% in terms of efficiency: in terms of production cost, it is estimated with some certainty to be able to reach the baseline of 1 DM/Watt peak output (W{sub p}). (orig.).

  19. Magnetic properties of thin Ni films measured by a dc SQUID-based magnetic microscope

    DEFF Research Database (Denmark)

    Snigirev, O.V.; Andreev, K.E.; Tishin, A.M.;

    1997-01-01

    We have applied a scanning HTS (high-temperature superconductor) de SQUID (superconducting quantum interference device) -based magnetic microscope to study the magnetic properties of Au/Ni/Si(100) films in the thickness range from 8 to 200 Angstrom at T = 77 K. A one-domain structure with in......-plane orientation of the magnetic moment was found for film thicknesses exceeding 26 Angstrom. A drastic decrease of the magnetization of the film was detected when the thickness is less than 26 Angstrom....

  20. Intrinsically conductive polymer thin film piezoresistors

    DEFF Research Database (Denmark)

    Lillemose, Michael; Spieser, Martin; Christiansen, N.O.;

    2008-01-01

    We report on the piezoresistive effect in the intrinsically conductive polymer, polyaniline. A process recipe for indirect patterning of thin film polyaniline has been developed. Using a specially designed chip, the polyaniline thin films have been characterised with respect to resistivity...... and strain sensitivity using two- and four-point measurement method. We have found that polyaniline has a negative gauge factor of K = -4.9, which makes it a candidate for piezoresistive read-out in polymer based MEMS-devices. (C) 2007 Elsevier B.V. All rights reserved....

  1. Thin Films Made Fast and Modified Fast

    International Nuclear Information System (INIS)

    Thin films are playing a more and more important role for technological applications and there are many aspects of materials surface processing and thin film production, ranging from simple heat treatments to ion implantation or laser surface treatments. These methods are often very complicated, involving many basic processes and they have to be optimized for the desired application. Nuclear methods, especially Moessbauer spectroscopy, can be successfully applied for this task and some examples will be presented for laser-beam and ion-beam based processes.

  2. Feasibility Study of Thin Film Thermocouple Piles

    Science.gov (United States)

    Sisk, R. C.

    2001-01-01

    Historically, thermopile detectors, generators, and refrigerators based on bulk materials have been used to measure temperature, generate power for spacecraft, and cool sensors for scientific investigations. New potential uses of small, low-power, thin film thermopiles are in the area of microelectromechanical systems since power requirements decrease as electrical and mechanical machines shrink in size. In this research activity, thin film thermopile devices are fabricated utilizing radio frequency sputter coating and photoresist lift-off techniques. Electrical characterizations are performed on two designs in order to investigate the feasibility of generating small amounts of power, utilizing any available waste heat as the energy source.

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

    Science.gov (United States)

    Mashooq, Kishwar; Talukder, Muhammad Anisuzzaman

    2016-05-01

    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

  4. Shielding superconductors with thin films

    CERN Document Server

    Posen, Sam; Catelani, Gianluigi; Liepe, Matthias U; Sethna, James P

    2015-01-01

    Determining the optimal arrangement of superconducting layers to withstand large amplitude AC magnetic fields is important for certain applications such as superconducting radiofrequency cavities. In this paper, we evaluate the shielding potential of the superconducting film/insulating film/superconductor (SIS') structure, a configuration that could provide benefits in screening large AC magnetic fields. After establishing that for high frequency magnetic fields, flux penetration must be avoided, the superheating field of the structure is calculated in the London limit both numerically and, for thin films, analytically. For intermediate film thicknesses and realistic material parameters we also solve numerically the Ginzburg-Landau equations. It is shown that a small enhancement of the superheating field is possible, on the order of a few percent, for the SIS' structure relative to a bulk superconductor of the film material, if the materials and thicknesses are chosen appropriately.

  5. The potential and challenges of thin-film electrolyte and nanostructured electrode for yttria-stabilized zirconia-base anode-supported solid oxide fuel cells

    Science.gov (United States)

    Noh, Ho-Sung; Yoon, Kyung Joong; Kim, Byung-Kook; Je, Hae-June; Lee, Hae-Weon; Lee, Jong-Ho; Son, Ji-Won

    2014-02-01

    Thin-film electrolytes and nanostructured electrodes are essential components for lowering the operation temperature of solid oxide fuel cells (SOFCs); however, reliably implementing thin-film electrolytes and nano-structure electrodes over a realistic SOFC platform, such as a porous anode-support, has been extremely difficult. If these components can be created reliably and reproducibly on porous substrates as anode supports, a more precise assessment of their impact on realistic SOFCs would be possible. In this work, structurally sound thin-film and nano-structured SOFC components consisting of a nano-composite NiO-yttria-stabilized zirconia (YSZ) anode interlayer, a thin YSZ and gadolinia-doped ceria (GDC) bi-layer electrolyte, and a nano-structure lanthanum strontium cobaltite (LSC)-base cathode, are sequentially fabricated on a porous NiO-YSZ anode support using thin-film technology. Using an optimized cell testing setup makes possible a more exact investigation of the potential and challenges of thin-film electrolyte and nanostructured electrode-based anode-supported SOFCs. Peak power densities obtained at 500 °C surpass 500 mW cm-2, which is an unprecedented low-temperature performance for the YSZ-based anode-supported SOFC. It is found that this critical, low-temperature performance for the anode-supported SOFC depends more on the electrode performance than the resistance of the thin-film electrolyte during lower temperature operation.

  6. Thin Film Solid Lubricant Development

    Science.gov (United States)

    Benoy, Patricia A.

    1997-01-01

    Tribological coatings for high temperature sliding applications are addressed. A sputter-deposited bilayer coating of gold and chromium is investigated as a potential solid lubricant for protection of alumina substrates during sliding at high temperature. Evaluation of the tribological properties of alumina pins sliding against thin sputtered gold films on alumina substrates is presented.

  7. Thin-liquid-film evaporation at contact line

    Institute of Scientific and Technical Information of China (English)

    Hao WANG; Zhenai PAN; Zhao CHEN

    2009-01-01

    When a liquid wets a solid wall, the extended meniscus near the contact line may be divided into three regions: a nonevaporating region, where the liquid is adsorbed on the wall; a transition region or thin-film region, where effects of long-range molecular forces (disjoining pressure) are felt; and an intrinsic meniscus region, where capillary forces dominate. The thin liquid film, with thickness from nanometers up to micrometers, covering the transition region and part of intrinsic meniscus, is gaining interest due to its high heat transfer rates. In this paper, a review was made of the researches on thin-liquid-film evaporation. The major characteristics of thin film, thin-film modeling based on continuum theory, simulations based on molecular dynamics, and thin-film profile and temperature measurements were summarized.

  8. Biocorrosion investigation of two shape memory nickel based alloys: Ni-Mn-Ga and thin film NiTi.

    Science.gov (United States)

    Stepan, L L; Levi, D S; Gans, E; Mohanchandra, K P; Ujihara, M; Carman, G P

    2007-09-01

    Thin film nitinol and single crystal Ni-Mn-Ga represent two new shape memory materials with potential to be used as percutaneously placed implant devices. However, the biocompatibility of these materials has not been adequately assessed. Immersion tests were conducted on both thin film nitinol and single crystal Ni-Mn-Ga in Hank's balanced salt solution at 37 degrees C and pH 7.4. After 12 h, large pits were found on the Ni-Mn-Ga samples while thin film nitinol displayed no signs of corrosion. Further electrochemical tests on thin film nitinol samples revealed breakdown potentials superior to a mechanically polished nitinol disc. These results suggest that passivation or electropolishing of thin film nitinol maybe unnecessary to promote corrosion resistance.

  9. Flexible pH sensors based on polysilicon thin film transistors and ZnO nanowalls

    Science.gov (United States)

    Maiolo, L.; Mirabella, S.; Maita, F.; Alberti, A.; Minotti, A.; Strano, V.; Pecora, A.; Shacham-Diamand, Y.; Fortunato, G.

    2014-09-01

    A fully flexible pH sensor using nanoporous ZnO on extended gate thin film transistor (EGTFT) fabricated on polymeric substrate is demonstrated. The sensor adopts the Low Temperature Polycrystalline Silicon (LTPS) TFT technology for the active device, since it allows excellent electrical characteristics and good stability and opens the way towards the possibility of exploiting CMOS architectures in the future. The nanoporous ZnO sensitive film, consisting of very thin (20 nm) crystalline ZnO walls with a large surface-to-volume ratio, was chemically deposited at 90 °C, allowing simple process integration with conventional TFT micro-fabrication processes compatible with wide range of polymeric substrates. The pH sensor showed a near-ideal Nernstian response (˜59 mV/pH), indicating an ideality factor α ˜ 1 according to the conventional site binding model. The present results can pave the way to advanced flexible sensing systems, where sensors and local signal conditioning circuits will be integrated on the same flexible substrate.

  10. Phase Coarsening in Thin Films

    Science.gov (United States)

    Wang, K. G.; Glicksman, M. E.

    2015-08-01

    Phase coarsening (Ostwald ripening) phenomena are ubiquitous in materials growth processes such as thin film formation. The classical theory explaining late-stage phase coarsening phenomena was developed by Lifshitz and Slyozov, and by Wagner in the 1960s. Their theory is valid only for a vanishing volume fraction of the second phase in three dimensions. However, phase coarsening in two-dimensional systems is qualitatively different from that in three dimensions. In this paper, the many-body concept of screening length is reviewed, from which we derive the growth law for a `screened' phase island, and develop diffusion screening theory for phase coarsening in thin films. The coarsening rate constant, maximum size of phase islands in films, and their size distribution function will be derived from diffusion screening theory. A critical comparison will be provided of prior coarsening concepts and improvements derived from screening approaches.

  11. Superfast Thinning of a Nanoscale Thin Liquid Film

    OpenAIRE

    Winkler, Michael; Kofod, Guggi; Krastev, Rumen; Abel, Markus

    2011-01-01

    This fluid dynamics video demonstrates an experiment on superfast thinning of a freestanding thin aqueous film. The production of such films is of fundamental interest for interfacial sciences and the applications in nanoscience. The stable phase of the film is of the order $5-50\\,nm$; nevertheless thermal convection can be established which changes qualitatively the thinning behavior from linear to exponentially fast. The film is thermally driven on one spot by a very cold needle, establishi...

  12. Networking Behavior in Thin Film and Nanostructure Growth Dynamics

    OpenAIRE

    Yuksel, Murat; Karabacak, Tansel; Guclu, Hasan

    2007-01-01

    Thin film coatings have been essential in development of several micro and nano-scale devices. To realize thin film coatings various deposition techniques are employed, each yielding surface morphologies with different characteristics of interest. Therefore, understanding and control of the surface growth is of great interest. In this paper, we devise a novel network-based modeling of the growth dynamics of such thin films and nano-structures. We specifically map dynamic steps taking place du...

  13. AlScN thin film based surface acoustic wave devices with enhanced microfluidic performance

    Science.gov (United States)

    Wang, W. B.; Fu, Y. Q.; Chen, J. J.; Xuan, W. P.; Chen, J. K.; Wang, X. Z.; Mayrhofer, P.; Duan, P. F.; Bittner, A.; Schmid, U.; Luo, J. K.

    2016-07-01

    This paper reports the characterization of scandium aluminum nitride (Al1-x Sc x N, x  =  27%) films and discusses surface acoustic wave (SAW) devices based on them. Both AlScN and AlN films were deposited on silicon by sputtering and possessed columnar microstructures with (0 0 0 2) crystal orientation. The AlScN/Si SAW devices showed improved electromechanical coupling coefficients (K 2, ~2%) compared with pure AlN films (hardness of the AlN film decreased significantly when Sc was doped, and this was responsible for the decreased acoustic velocity and resonant frequency, and the increased temperature coefficient of frequency, of the AlScN SAW devices.

  14. Polarization Fatigue in Ferroelectric Thin Films

    Institute of Scientific and Technical Information of China (English)

    王忆; K.H.WONG; 吴文彬

    2002-01-01

    The fatigue problem in ferroelectric thin films is investigated based on the switched charge per unit area versus switching cycles. The temperature, dielectric permittivity, voltage bias, frequency and defect valence dependent switching polarization properties are calculated quantitatively with an extended Dawber-Scott model. The results are in agreement with the recent experiments.

  15. Fabrication and properties of the meander nanowires based on ultra-thin Nb films

    Science.gov (United States)

    Zhao, Lu; Jin, Yi-Rong; Li, Jie; Deng, Hui; Zheng, Dong-Ning

    2014-08-01

    We report the fabrication and the study of superconducting properties of ultra-thin Nb superconducting meander nanowires, which can be used as superconducting nanowire single-photon detectors (SNSPDs). The ultra-thin (about 7-nm thick) Nb films are patterned into micro-bridges, and 100-nm wide meander nanowires by using e-beam lithography (EBL). The average transition temperature (Tc) of the nanowires is about 4.8 K and the critical current density jc is about 2.8 × 106 A/cm2. Superconducting characteristics of the specimens at different applied magnetic fields up to 8 T (parallel or perpendicular to the specimen) are systematically investigated. The normalized temperature t (= T/Tc) dependences of the parallel critical field (Hc‖) for both the micro-bridge and the meander nanowire are almost the same, following the Ginzburg and Landau (GL) formalism for ultra-thin films. However, in perpendicular field and in the vicinity of Tc (> 0.95Tc), the critical field Hc‖ of the nanowire exhibits a down-turn curvature nonlinear temperature dependence while the micro-bridge displays a linear temperature dependence. The nonlinear behavior of Hc⊥ in the nanowire is believed to be due to the fact that in the vicinity of Tc the coherence length becomes larger than the line width. Additionally, the localization of carriers in the nanowire could also contribute to the nonlinear behavior. The resistive transitions could be described by the phase-slip model for quasi-one-dimensional system. Moreover, the hysteresis in I-V curve of the meander nanowires can be illustrated by a simple model of localized normal hotspot maintained by Joule heating.

  16. Novel top-contact monolayer pentacene-based thin-film transistor for ammonia gas detection.

    Science.gov (United States)

    Mirza, Misbah; Wang, Jiawei; Li, Dexing; Arabi, S Atika; Jiang, Chao

    2014-04-23

    We report on the fabrication of an organic field-effect transistor (OFET) of a monolayer pentacene thin film with top-contact electrodes for the aim of ammonia (NH3) gas detection by monitoring changes in its drain current. A top-contact configuration, in which source and drain electrodes on a flexible stamp [poly(dimethylsiloxane)] were directly contacted with the monolayer pentacene film, was applied to maintain pentacene arrangement ordering and enhance the monolayer OFET detection performance. After exposure to NH3 gas, the carrier mobility at the monolayer OFET channel decreased down to one-third of its original value, leading to a several orders of magnitude decrease in the drain current, which tremendously enhanced the gas detection sensitivity. This sensitivity enhancement to a limit of the 10 ppm level was attributed to an increase of charge trapping in the carrier channel, and the amount of trapped states was experimentally evaluated by the threshold voltage shift induced by the absorbed NH3 molecular analyte. In contrast, a conventional device with a 50-nm-thick pentacene layer displayed much higher mobility but lower response to NH3 gas, arising from the impediment of analyte penetrating into the conductive channel, owing to the thick pentacene film.

  17. Tailoring electronic structure of polyazomethines thin films

    Directory of Open Access Journals (Sweden)

    J. Weszka

    2010-09-01

    Full Text Available Purpose: The aim of this work is to show how electronic properties of polyazomethine thin films deposited by chemical vapor deposition method (CVD can be tailored by manipulating technological parameters of pristine films preparation as well as modifying them while the as-prepared films put into iodine atmosphere.Design/methodology/approach: The recent achievements in the field of designing and preparation methods to be used while preparing polymer photovoltaic solar cells or optoelectronic devices.Findings: The method used allow for pure pristine polymer thin films to be prtepared without any unintentional doping taking place during prepoaration methods. This is a method based on polycondensation process, where polymer chain developing is running directly due to chemical reaction between molecules of bifunctional monomers. The method applied to prepare thin films of polyazomethines takes advantage of monomer transporting by mreans of neutral transport agent as pure argon is.Research limitations/implications: The main disadvantage of alternately conjugated polymers seems to be quite low mobility of charge carrier that is expected to be a consequence of their backbone being built up of sp2 hybridized carbon and nitrogen atoms. Varying technological conditions towards increasing reagents mass transport to the substrate is expected to give such polyazomethine thin films organization that phenylene rin stacking can result in special π electron systems rather than linear ones as it is the case.Originality/value: Our results supply with original possibilities which can be useful in ooking for good polymer materials for optoelectronic and photovoltaic applications. These results have been gained on polyazomethine thin films but their being isoelectronic counterpart to widely used poly p-phenylene vinylene may be very convenient to develop high efficiency polymer solar cells

  18. Electronic and optical device applications of hollow cathode plasma assisted atomic layer deposition based GaN thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bolat, Sami, E-mail: bolat@ee.bilkent.edu.tr; Tekcan, Burak [Department of Electrical and Electronics Engineering, Bilkent University, 06800, Ankara, Turkey and UNAM, National Nanotechnology Research Center, Bilkent University, 06800, Ankara (Turkey); Ozgit-Akgun, Cagla; Biyikli, Necmi [UNAM, National Nanotechnology Research Center, Bilkent University, 06800, Ankara, Turkey and Institute of Materials Science and Nanotechnology, Bilkent University, 06800, Ankara (Turkey); Okyay, Ali Kemal, E-mail: aokyay@ee.bilkent.edu.tr [Department of Electrical and Electronics Engineering, Bilkent University, 06800, Ankara (Turkey); UNAM, National Nanotechnology Research Center, Bilkent University, 06800, Ankara (Turkey); Institute of Materials Science and Nanotechnology, Bilkent University, 06800, Ankara (Turkey)

    2015-01-15

    Electronic and optoelectronic devices, namely, thin film transistors (TFTs) and metal–semiconductor–metal (MSM) photodetectors, based on GaN films grown by hollow cathode plasma-assisted atomic layer deposition (PA-ALD) are demonstrated. Resistivity of GaN thin films and metal-GaN contact resistance are investigated as a function of annealing temperature. Effect of the plasma gas and postmetallization annealing on the performances of the TFTs as well as the effect of the annealing on the performance of MSM photodetectors are studied. Dark current to voltage and responsivity behavior of MSM devices are investigated as well. TFTs with the N{sub 2}/H{sub 2} PA-ALD based GaN channels are observed to have improved stability and transfer characteristics with respect to NH{sub 3} PA-ALD based transistors. Dark current of the MSM photodetectors is suppressed strongly after high-temperature annealing in N{sub 2}:H{sub 2} ambient.

  19. Activation of CdTe-based thin films with zinc chloride and tetrachlorozincates

    Energy Technology Data Exchange (ETDEWEB)

    Drost, C., E-mail: christian.drost@ctf-solar.com [CTF Solar GmbH, Manfred von Ardenne Ring 20 F, 01099 Dresden (Germany); Siepchen, B.; Krishnakumar, V.; Späth, B.; Kraft, C. [CTF Solar GmbH, Manfred von Ardenne Ring 20 F, 01099 Dresden (Germany); Modes, T.; Zywitzki, O. [Fraunhofer Institute for Electron Beam and Plasma Technology FEP, Winterbergstrasse 28, 01277 Dresden (Germany)

    2015-05-01

    A series of CdTe thin film solar cells were prepared by applying aqueous solutions of ZnCl{sub 2} or tetrachlorozincates M{sub n}ZnCl{sub 4} (M = Na or NH{sub 4} for n = 2; M = Mg or Ca for n = 1) as flux reagents in the activation process, instead of established but highly toxic CdCl{sub 2}. The remaining process steps for the generation of solar cells have not been varied and activation-temperature and -duration were kept constant with 400 °C/25 min. The back contact comprised an etching step followed by deposition of ca. 150 nm gold. In contrast to Na{sub 2}ZnCl{sub 4} and (NH{sub 4}){sub 2}ZnCl{sub 4}, the application of ZnCl{sub 2} or CaZnCl{sub 4} in 30% concentration gave promising results with current-voltage and quantum efficiency cell-data well comparable to CdCl{sub 2} standard activated reference cells. The aqueous solutions were either applied manually by dip-coating or sponge roller procedure. Microstructural and interfacial investigations were performed with high resolution field emission scanning electron microscopy imaging on polished cross sections of ZnCl{sub 2}- or CaZnCl{sub 4}-derived devices using ion beam preparation techniques. Moreover, the measurement of the electron beam induced current was achieved, yielding a similar appearance for a CaZnCl{sub 4}-activated substrate compared to referential CdCl{sub 2} samples. - Highlights: • ZnCl{sub 2} or CaZnCl{sub 4} can substitute toxic CdCl{sub 2} in the activation of CdTe. • Activation process parameters are similar to standard CdCl{sub 2} activation. • Well comparable current-voltage cell data is obtained for Zn-based activation. • Microstructure for Zn-based cells compares well with standard CdCl{sub 2}-cells.

  20. Metallic Thin-Film Bonding and Alloy Generation

    Science.gov (United States)

    Fryer, Jack Merrill (Inventor); Campbell, Geoff (Inventor); Peotter, Brian S. (Inventor); Droppers, Lloyd (Inventor)

    2016-01-01

    Diffusion bonding a stack of aluminum thin films is particularly challenging due to a stable aluminum oxide coating that rapidly forms on the aluminum thin films when they are exposed to atmosphere and the relatively low meting temperature of aluminum. By plating the individual aluminum thin films with a metal that does not rapidly form a stable oxide coating, the individual aluminum thin films may be readily diffusion bonded together using heat and pressure. The resulting diffusion bonded structure can be an alloy of choice through the use of a carefully selected base and plating metals. The aluminum thin films may also be etched with distinct patterns that form a microfluidic fluid flow path through the stack of aluminum thin films when diffusion bonded together.

  1. Interlayer coupling dependent magnetic properties in amorphous and nanocrystalline FeTaC based multilayer thin films

    International Nuclear Information System (INIS)

    comprehensive study on the multistep magnetization reversal behavior in multilayer structured FeTaC based thin films. (paper)

  2. Interlayer coupling dependent magnetic properties in amorphous and nanocrystalline FeTaC based multilayer thin films

    Science.gov (United States)

    Singh, Akhilesh K.; Perumal, Alagarsamy

    2016-03-01

    comprehensive study on the multistep magnetization reversal behavior in multilayer structured FeTaC based thin films.

  3. Humidity sensing characteristics of hydrotungstite thin films

    Indian Academy of Sciences (India)

    G V Kunte; S A Shivashankar; A M Umarji

    2008-11-01

    Thin films of the hydrated phase of tungsten oxide, hydrotungstite (H2WO4.H2O), have been grown on glass substrates using a dip-coating technique. The -axis oriented films have been characterized by X-ray diffraction and scanning electron microscopy. The electrical conductivity of the films is observed to vary with humidity and selectively show high sensitivity to moisture at room temperature. In order to understand the mechanism of sensing, the films were examined by X-ray diffraction at elevated temperatures and in controlled atmospheres. Based on these observations and on conductivity measurements, a novel sensing mechanism based on protonic conduction within the surface layers adsorbed onto the hydrotungstite film is proposed.

  4. Room temperature analysis of dielectric function of ZnO-based thin film on fused quartz substrate

    Energy Technology Data Exchange (ETDEWEB)

    Kurniawan, Robi; Sutjahja, Inge M.; Winata, Toto [Department of Physics, Institut Teknologi Bandung, Ganesa 10 Bandung 40132 (Indonesia); Rusydi, Andrivo; Darma, Yudi, E-mail: yudi@fi.itb.ac.id [Department of Physics, Institut Teknologi Bandung, Ganesa 10 Bandung 40132 (Indonesia); Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore 117603 (Singapore); NUSNNI-Nanocore, Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore)

    2015-09-30

    A set of sample consist of pure ZnO and Cu-doped ZnO film were grown on fused-quartz substrates using pulsed laser deposition (PLD) technique. Here, we report room temperature spectroscopic ellipsometry analysis (covering energy range of 0.5 to 6.3 eV) of pure ZnO film and Cu doped ZnO film at 8 in at. %. The thickness of pure ZnO and Cu-doped ZnO film using in this study is about 350 nm. To extract the dielectric function of ZnO thin film, multilayer modeling is performed which takes into account reflections at each interface through Fresnel coefficients. This method based on Drude-Lorentz models that connect with Kramers-Kronig relations. The best fitting of Ψ (amplitude ratio) and Δ (phase difference) taken by SE measurement are obtained reasonably well by mean the universal fitting of three different photon incident angles. The imaginary part of dielectric function (ε{sub 2}) show the broad peak at around 3.3 eV assigned as combination of optical band energy edge with excitonic states. The exitonic states could not be observed clearly in this stage. The evolution of extracted dielectric function is observable by introducing 8% Cu as indicated by decreasing of excitonic intensity. This result indicates the screening of excitonic state. This study will bring us to have a good undestanding for the role of Cu impurities for ZnO thin films.

  5. Plasma polymerized hydrogel thin films

    Energy Technology Data Exchange (ETDEWEB)

    Tamirisa, Prabhakar A. [School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Koskinen, Jere [Institute of Paper Science and Technology, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Hess, Dennis W. [School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States)]. E-mail: dennis.hess@chbe.gatech.edu

    2006-12-05

    Plasma polymerization was used to produce thermoresponsive hydrogel films of N-isopropylacrylamide (NIPAAm) in a single deposition step. Solvent free processing to produce laterally confined intelligent hydrogel films offers the potential for high volume production of micro-sensors/actuators. Through variation of reactor conditions such as deposition pressure and substrate temperature, it is possible to tailor and control chemical properties of the films such as crosslink density and thus swelling. Fabrication of hydrogel thin films with adequate crosslinks is critical to ensuring adhesion to substrates and stability in aqueous environments. Chemical bonding structures in plasma polymerized NIPAAm were studied using Fourier transform infrared spectroscopy and the thermoresponsive nature of plasma polymerized NIPAAm was confirmed through contact angle goniometry. A reversible temperature dependent contact angle change was observed.

  6. Design and Simulation of the Thin Film Pulse Transformer

    Institute of Scientific and Technical Information of China (English)

    LIU Bao-yuan; SHI Yu; WEN Qi-ye

    2005-01-01

    A new thin film pulse transformer for using in ISND and ADSL systems has been designed based on a domain wall pinning model, the parameters of nano-magnetic thin film such as permeability and coercivity can be calculated. The main properties of the thin film transformer including the size,parallel inductance, Q value and turn ratio have been simulated and optimized. Simulation results show that the thin film transformer can be fairly operated in a frequency range of 0. 001~20 MHz.

  7. Flexible fluidic microchips based on thermoformed and locally modified thin polymer films

    NARCIS (Netherlands)

    Truckenmüller, R.; Giselbrecht, S.; Blitterswijk, van C.; Dambrowsky, N.; Gottwald, E.; Mappes, T.; Rolletschek, A.; Saile, V.; Trautmann, C.; Weibezahn, K.-F.; Welle, A.

    2008-01-01

    This paper presents a fundamentally new approach for the manufacturing and the possible applications of lab on a chip devices, mainly in the form of disposable fluidic microchips for life sciences applications. The new technology approach is based on a novel microscale thermoforming of thin polymer

  8. Fabrication of organic semiconducting materials and high-performance organic thin-film transistors based on electron-irradiated polystyrene

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyeok Moo

    2011-02-15

    It was discovered that non-luminescent polystyrene (PS) can be converted to luminescent materials whose color can be changed in a wide visible range by electron irradiation. After the analyses of electron-irradiated PS, it was found that polycyclic aromatic hydrocarbons are produced by the irradiation and these PAHs are the origin of the luminescence from the electron-irradiated polymer. Based on the finding, a straightforward approach to produce desired light-emitting nanoarchitectures and nanopatterns only by irradiating an electron beam to the polymer was presented. In particular, the top-down irradiation approach provides a powerful tool to fabricate a variety of interesting nanoarchitectures when combined with bottom-up approaches; PS nanostructures prepared by self-assembling techniques can be directly transformed to luminescent nanostructures by electron irradiation while keeping their pristine morphologies. Light-emitting materials are widely used for optical, photonic, chemical and biomedical devices and a rapid progress in the devices requires well-defined luminescent nanoarchitectures. The approach presented here will be useful for a wide range of research fields including optics, photonics, chemistry, and biologics. On the other hand, a very simple but effective approach to produce high-performance rubrene organic thin-film transistors (OTFTs) with characteristics better than amorphous silicon TFTs was presented. Only by an abrupt heating process, high-quality crystalline rubrene semiconductor thin films that have almost ideal structures for OTFTs are created. The produced crystalline thin films consist of highly ordered, uniaxially oriented single-crystalline grains with large average sizes and the grains are interconnected with one another to form continuous films over the whole dielectric surfaces. Such high-quality crystalline rubrene thin films are remarkably rapidly produced in just 30 sec through this approach. Moreover, the increase of carrier

  9. Selective inorganic thin films

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, M.L.F.; Pohl, P.I.; Brinker, C.J. [Sandia National Labs., Albuquerque, NM (United States)

    1997-04-01

    Separating light gases using membranes is a technology area for which there exists opportunities for significant energy savings. Examples of industrial needs for gas separation include hydrogen recovery, natural gas purification, and dehydration. A membrane capable of separating H{sub 2} from other gases at high temperatures could recover hydrogen from refinery waste streams, and facilitate catalytic dehydrogenation and the water gas shift (CO + H{sub 2}O {yields} H{sub 2} + CO{sub 2}) reaction. Natural gas purification requires separating CH{sub 4} from mixtures with CO{sub 2}, H{sub 2}S, H{sub 2}O, and higher alkanes. A dehydrating membrane would remove water vapor from gas streams in which water is a byproduct or a contaminant, such as refrigeration systems. Molecular sieve films offer the possibility of performing separations involving hydrogen, natural gas constituents, and water vapor at elevated temperatures with very high separation factors. It is in applications such as these that the authors expect inorganic molecular sieve membranes to compete most effectively with current gas separation technologies. Cryogenic separations are very energy intensive. Polymer membranes do not have the thermal stability appropriate for high temperature hydrogen recovery, and tend to swell in the presence of hydrocarbon natural gas constituents. The authors goal is to develop a family of microporous oxide films that offer permeability and selectivity exceeding those of polymer membranes, allowing gas membranes to compete with cryogenic and adsorption technologies for large-scale gas separation applications.

  10. Gallium nitride based thin films for photon and particle radiation dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Hofstetter, Markus

    2012-07-23

    Ionization chambers have been used since the beginning of the 20th century for measuring ionizing radiation and still represent the ''gold standard'' in dosimetry. However, since the sensitivity of the devices is proportional to the detection volume, ionization chambers are not common in numerous medical applications, such as imaging. In these fields, spatially resolved dose information is, beside film-systems, usually measured with scintillators and photo-multipliers, which is a relatively complex and expensive technique. For thus much effort has been focused on the development of novel detection systems in the last decades and especially in the last few years. Examples include germanium or silicon photoconductive detectors, MOSFETs, and PIN-diodes. Although for these systems, miniaturization for spatially resolved detection is possible, they suffer from a range of disadvantages. Characteristics such as poor measurement stability, material degradation, and/or a limited measurement range prevent routine application of these techniques in medical diagnostic devices. This work presents the development and evaluation of gallium nitride (GaN) thin films and heterostructures to validate their application in x-ray detection in the medical regime. Furthermore, the impact of particle radiation on device response was investigated. Although previous publications revealed relatively low energy absorption of GaN, it is possible to achieve very high signal amplification factors inside the material due to an appropriate sensor configuration, which, in turn, compensates the low energy absorption. Thus, gallium nitride can be used as a photo-conductor with ohmic contacts. The conductive volume of the sensor changes in the presence of external radiation, which results in an amplified measurement signal after applying a bias voltage to the device. Experiments revealed a sensitivity of the device between air kerma rates of 1 {mu}Gy/s and 20 mGy/s. In this range

  11. Memory operation devices based on light-illumination ambipolar carbon-nanotube thin-film-transistors

    Energy Technology Data Exchange (ETDEWEB)

    Aïssa, B., E-mail: aissab@emt.inrs.ca [Qatar Environment and Energy Research Institute (QEERI), Qatar Foundation, P.O. Box 5825, Doha (Qatar); Centre Energie, Matériaux et Télécommunications, INRS, 1650, Boulevard Lionel-Boulet Varennes, Quebec J3X 1S2 (Canada); Nedil, M. [Telebec Wireless Underground Communication Laboratory, UQAT, 675, 1ère Avenue, Val d' Or, Quebec J9P 1Y3 (Canada); Kroeger, J. [NanoIntegris & Raymor Nanotech, Raymor Industries Inc., 3765 La Vérendrye, Boisbriand, Quebec J7H 1R8 (Canada); Haddad, T. [Department of Mechanical Engineering, McGill University, Montreal, Quebec H3A 0B8 (Canada); Rosei, F. [Centre Energie, Matériaux et Télécommunications, INRS, 1650, Boulevard Lionel-Boulet Varennes, Quebec J3X 1S2 (Canada)

    2015-09-28

    We report the memory operation behavior of a light illumination ambipolar single-walled carbon nanotube thin film field-effect transistors devices. In addition to the high electronic-performance, such an on/off transistor-switching ratio of 10{sup 4} and an on-conductance of 18 μS, these memory devices have shown a high retention time of both hole and electron-trapping modes, reaching 2.8 × 10{sup 4} s at room temperature. The memory characteristics confirm that light illumination and electrical field can act as an independent programming/erasing operation method. This could be a fundamental step toward achieving high performance and stable operating nanoelectronic memory devices.

  12. Nanostructured thin film-based near-infrared tunable perfect absorber using phase-change material

    Science.gov (United States)

    Kocer, Hasan

    2015-01-01

    Nanostructured thin film absorbers embedded with phase-change thermochromic material can provide a large level of absorption tunability in the near-infrared region. Vanadium dioxide was employed as the phase-change material in the designed structures. The optical absorption properties of the designed structures with respect to the geometric and material parameters were systematically investigated using finite-difference time-domain computations. Absorption level of the resonance wavelength in the near-IR region was tuned from the perfect absorption level to a low level (17%) with a high positive dynamic range of near-infrared absorption intensity tunability (83%). Due to the phase transition of vanadium dioxide, the resonance at the near-infrared region is being turned on and turned off actively and reversibly under the thermal bias, thereby rendering these nanostructures suitable for infrared camouflage, emitters, and sensors.

  13. Numerical simulation of offset-drain amorphous oxide-based thin-film transistors

    Science.gov (United States)

    Jeong, Jaewook

    2016-11-01

    In this study, we analyzed the electrical characteristics of amorphous indium–gallium–zinc-oxide (a-IGZO) thin-film transistors (TFTs) with an offset-drain structure by technology computer aided design (TCAD) simulation. When operating in a linear region, an enhancement-type TFT shows poor field-effect mobility because most conduction electrons are trapped in acceptor-like defects in an offset region when the offset length (L off) exceeds 0.5 µm, whereas a depletion-type TFT shows superior field-effect mobility owing to the high free electron density in the offset region compared with the trapped electron density. When operating in the saturation region, both types of TFTs show good field-effect mobility comparable to that of a reference TFT with a large gate overlap. The underlying physics of the depletion and enhancement types of offset-drain TFTs are systematically analyzed.

  14. Amorphous Zinc Oxide Integrated Wavy Channel Thin Film Transistor Based High Performance Digital Circuits

    KAUST Repository

    Hanna, Amir

    2015-12-04

    High performance thin film transistor (TFT) can be a great driving force for display, sensor/actuator, integrated electronics, and distributed computation for Internet of Everything applications. While semiconducting oxides like zinc oxide (ZnO) present promising opportunity in that regard, still wide area of improvement exists to increase the performance further. Here, we show a wavy channel (WC) architecture for ZnO integrated TFT which increases transistor width without chip area penalty, enabling high performance in material agnostic way. We further demonstrate digital logic NAND circuit using the WC architecture and compare it to the conventional planar architecture. The WC architecture circuits have shown 2× higher peak-to-peak output voltage for the same input voltage. They also have 3× lower high-to-low propagation delay times, respectively, when compared to the planar architecture. The performance enhancement is attributed to both extra device width and enhanced field effect mobility due to higher gate field electrostatics control.

  15. Memory operation devices based on light-illumination ambipolar carbon-nanotube thin-film-transistors

    International Nuclear Information System (INIS)

    We report the memory operation behavior of a light illumination ambipolar single-walled carbon nanotube thin film field-effect transistors devices. In addition to the high electronic-performance, such an on/off transistor-switching ratio of 104 and an on-conductance of 18 μS, these memory devices have shown a high retention time of both hole and electron-trapping modes, reaching 2.8 × 104 s at room temperature. The memory characteristics confirm that light illumination and electrical field can act as an independent programming/erasing operation method. This could be a fundamental step toward achieving high performance and stable operating nanoelectronic memory devices

  16. A stretchable strain sensor based on a metal nanoparticle thin film for human motion detection

    Science.gov (United States)

    Lee, Jaehwan; Kim, Sanghyeok; Lee, Jinjae; Yang, Daejong; Park, Byong Chon; Ryu, Seunghwa; Park, Inkyu

    2014-09-01

    Wearable strain sensors for human motion detection are being highlighted in various fields such as medical, entertainment and sports industry. In this paper, we propose a new type of stretchable strain sensor that can detect both tensile and compressive strains and can be fabricated by a very simple process. A silver nanoparticle (Ag NP) thin film patterned on the polydimethylsiloxane (PDMS) stamp by a single-step direct transfer process is used as the strain sensing material. The working principle is the change in the electrical resistance caused by the opening/closure of micro-cracks under mechanical deformation. The fabricated stretchable strain sensor shows highly sensitive and durable sensing performances in various tensile/compressive strains, long-term cyclic loading and relaxation tests. We demonstrate the applications of our stretchable strain sensors such as flexible pressure sensors and wearable human motion detection devices with high sensitivity, response speed and mechanical robustness.Wearable strain sensors for human motion detection are being highlighted in various fields such as medical, entertainment and sports industry. In this paper, we propose a new type of stretchable strain sensor that can detect both tensile and compressive strains and can be fabricated by a very simple process. A silver nanoparticle (Ag NP) thin film patterned on the polydimethylsiloxane (PDMS) stamp by a single-step direct transfer process is used as the strain sensing material. The working principle is the change in the electrical resistance caused by the opening/closure of micro-cracks under mechanical deformation. The fabricated stretchable strain sensor shows highly sensitive and durable sensing performances in various tensile/compressive strains, long-term cyclic loading and relaxation tests. We demonstrate the applications of our stretchable strain sensors such as flexible pressure sensors and wearable human motion detection devices with high sensitivity, response

  17. Non-toxic and environmentally friendly route for preparation of copper indium sulfide based thin film solar cells

    International Nuclear Information System (INIS)

    Highlights: • Substrate structure of spray pyrolyzed CuInS2/In2S3 heterojunction solar cells. • Low cost and environmentally friendly fabrication of CuInS2 based solar cells. • Low RF power deposition of TCO layer. • AZO–Ag–AZO sandwich structure. • Effect of the thickness of buffer layer on the photovoltaic performance. - Abstract: In this study, copper based thin film solar cells with substrate structure have been built via spray pyrolysis method. Toxic material usage was avoided during the material deposition and the post-treatment steps. Novel device configuration of Mo/CuInS2/In2S3/ZnO/AZO–Ag–AZO was studied as a function of the In2S3 buffer layer thickness. In order to utilize the zinc oxide (ZnO) and aluminum doped zinc oxide (AZO) transparent conductive layers, deposited by physical vapor deposition (PVD), on top of the spray pyrolyzed thin films, the RF power was lowered to 30 W. Although this minimized the unwanted penetration of the highly energetic particles, created during PVD process, sheet resistivity of the AZO films increased enormously. Hence very thin silver layer has been deposited between two AZO films. This resulted the decrease in the sheet resistivity more than 106 times. Electrical measurements under illumination revealed that short circuit current density (Jsc), open circuit voltage (Voc), fill factor (FF) and efficiency (η) of the Mo/CuInS2/In2S3/ZnO/AZO–Ag–AZO type solar cells increased with increasing the thickness of the In2S3 layer. The maximum Jsc of 9.20 mA/cm2, Voc of 0.43 V, FF of 0.44 have been observed for the 0.94 μm-thick In2S3 layer. Extraordinarily thick buffer layer provided better diffusion barrier between the absorber and the TCO layers and also resulted better photosensitivity. These could be the key factors to produce substrate configuration of the spray pyrolyzed thin film solar cells

  18. Non-toxic and environmentally friendly route for preparation of copper indium sulfide based thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Sankir, Nurdan Demirci, E-mail: nsankir@etu.edu.tr; Aydin, Erkan; Ugur, Esma; Sankir, Mehmet

    2015-08-15

    Highlights: • Substrate structure of spray pyrolyzed CuInS{sub 2}/In{sub 2}S{sub 3} heterojunction solar cells. • Low cost and environmentally friendly fabrication of CuInS{sub 2} based solar cells. • Low RF power deposition of TCO layer. • AZO–Ag–AZO sandwich structure. • Effect of the thickness of buffer layer on the photovoltaic performance. - Abstract: In this study, copper based thin film solar cells with substrate structure have been built via spray pyrolysis method. Toxic material usage was avoided during the material deposition and the post-treatment steps. Novel device configuration of Mo/CuInS{sub 2}/In{sub 2}S{sub 3}/ZnO/AZO–Ag–AZO was studied as a function of the In{sub 2}S{sub 3} buffer layer thickness. In order to utilize the zinc oxide (ZnO) and aluminum doped zinc oxide (AZO) transparent conductive layers, deposited by physical vapor deposition (PVD), on top of the spray pyrolyzed thin films, the RF power was lowered to 30 W. Although this minimized the unwanted penetration of the highly energetic particles, created during PVD process, sheet resistivity of the AZO films increased enormously. Hence very thin silver layer has been deposited between two AZO films. This resulted the decrease in the sheet resistivity more than 10{sup 6} times. Electrical measurements under illumination revealed that short circuit current density (J{sub sc}), open circuit voltage (V{sub oc}), fill factor (FF) and efficiency (η) of the Mo/CuInS{sub 2}/In{sub 2}S{sub 3}/ZnO/AZO–Ag–AZO type solar cells increased with increasing the thickness of the In{sub 2}S{sub 3} layer. The maximum J{sub sc} of 9.20 mA/cm{sup 2}, V{sub oc} of 0.43 V, FF of 0.44 have been observed for the 0.94 μm-thick In{sub 2}S{sub 3} layer. Extraordinarily thick buffer layer provided better diffusion barrier between the absorber and the TCO layers and also resulted better photosensitivity. These could be the key factors to produce substrate configuration of the spray pyrolyzed

  19. Thin films of soft matter

    CERN Document Server

    Kalliadasis, Serafim

    2007-01-01

    A detailed overview and comprehensive analysis of the main theoretical and experimental advances on free surface thin film and jet flows of soft matter is given. At the theoretical front the book outlines the basic equations and boundary conditions and the derivation of low-dimensional models for the evolution of the free surface. Such models include long-wave expansions and equations of the boundary layer type and are analyzed via linear stability analysis, weakly nonlinear theories and strongly nonlinear analysis including construction of stationary periodic and solitary wave and similarity solutions. At the experimental front a variety of very recent experimental developments is outlined and the link between theory and experiments is illustrated. Such experiments include spreading drops and bubbles, imbibitions, singularity formation at interfaces and experimental characterization of thin films using atomic force microscopy, ellipsometry and contact angle measurements and analysis of patterns using Minkows...

  20. Polycrystalline thin films : A review

    Energy Technology Data Exchange (ETDEWEB)

    Valvoda, V. [Charles Univ., Prague (Czech Republic). Faculty of Mathematics and Physics

    1996-09-01

    Polycrystalline thin films can be described in terms of grain morphology and in terms of their packing by the Thornton`s zone model as a function of temperature of deposition and as a function of energy of deposited atoms. Grain size and preferred grain orientation (texture) can be determined by X-ray diffraction (XRD) methods. A review of XRD analytical methods of texture analysis is given with main attention paid to simple empirical functions used for texture description and for structure analysis by joint texture refinement. To illustrate the methods of detailed structure analysis of thin polycrystalline films, examples of multilayers are used with the aim to show experiments and data evaluation to determine layer thickness, periodicity, interface roughness, lattice spacing, strain and the size of diffraction coherent volumes. The methods of low angle and high angle XRD are described and discussed with respect to their complementary information content.

  1. Synthesis and characterization of VO2-based thermochromic thin films for energy-efficient windows

    Science.gov (United States)

    Batista, Carlos; Ribeiro, Ricardo M.; Teixeira, Vasco

    2011-12-01

    Thermochromic VO2 thin films have successfully been grown on SiO2-coated float glass by reactive DC and pulsed-DC magnetron sputtering. The influence of substitutional doping of V by higher valence cations, such as W, Mo, and Nb, and respective contents on the crystal structure of VO2 is evaluated. Moreover, the effectiveness of each dopant element on the reduction of the intrinsic transition temperature and infrared modulation efficiency of VO2 is discussed. In summary, all the dopant elements--regardless of the concentration, within the studied range-- formed a solid solution with VO2, which was the only compound observed by X-ray diffractometry. Nb showed a clear detrimental effect on the crystal structure of VO2. The undoped films presented a marked thermochromic behavior, specially the one prepared by pulsed-DC sputtering. The dopants effectively decreased the transition of VO2 to the proximity of room temperature. However, the IR modulation efficiency is markedly affected as a consequence of the increased metallic character of the semiconducting phase. Tungsten proved to be the most effective element on the reduction of the semiconducting-metal transition temperature, while Mo and Nb showed similar results with the latter being detrimental to the thermochromism.

  2. Synthesis and characterization of VO2-based thermochromic thin films for energy-efficient windows

    Directory of Open Access Journals (Sweden)

    Batista Carlos

    2011-01-01

    Full Text Available Abstract Thermochromic VO2 thin films have successfully been grown on SiO2-coated float glass by reactive DC and pulsed-DC magnetron sputtering. The influence of substitutional doping of V by higher valence cations, such as W, Mo, and Nb, and respective contents on the crystal structure of VO2 is evaluated. Moreover, the effectiveness of each dopant element on the reduction of the intrinsic transition temperature and infrared modulation efficiency of VO2 is discussed. In summary, all the dopant elements--regardless of the concentration, within the studied range-- formed a solid solution with VO2, which was the only compound observed by X-ray diffractometry. Nb showed a clear detrimental effect on the crystal structure of VO2. The undoped films presented a marked thermochromic behavior, specially the one prepared by pulsed-DC sputtering. The dopants effectively decreased the transition of VO2 to the proximity of room temperature. However, the IR modulation efficiency is markedly affected as a consequence of the increased metallic character of the semiconducting phase. Tungsten proved to be the most effective element on the reduction of the semiconducting-metal transition temperature, while Mo and Nb showed similar results with the latter being detrimental to the thermochromism.

  3. Nanostructured zinc oxide thin film for application to surface plasmon resonance based cholesterol biosensor

    Science.gov (United States)

    Kaur, Gurpreet; Tomar, Monika; Gupta, Vinay

    2015-11-01

    ZnO thin film was deposited on gold coated glass prism by RF sputtering technique in glancing angle deposition (GLAD) configuration. The structural, morphological and optical properties of the deposited film were investigated using X-ray diffraction (XRD), Atomic Force Microscopy (AFM) and Fourier Transform Infrared (FTIR) Spectroscopy. ZnO coated Au prisms (ZnO/Au/prism) were used to excite surface plasmons in Kretschmann configuration at the Au- ZnO interface on a laboratory assembled Surface Plasmon Resonance (SPR) measurement setup. Cholesterol oxidase (ChOx) enzyme was immobilized on the ZnO/Au/prism structure by physical adsorption technique. Polydimethylsiloxane (PDMS) microchannels were fabricated over ChOx/ZnO/Au/prism system and various concentrations of cholesterol were passed over the sensor surface. The concentration of cholesterol was varied from 0.12 to 10.23 mM and the SPR reflectance curves were recorded in both static as well as dynamic modes demonstrating a high sensitivity of 0.36° mM-1.

  4. Water-soluble thin film transistors and circuits based on amorphous indium-gallium-zinc oxide.

    Science.gov (United States)

    Jin, Sung Hun; Kang, Seung-Kyun; Cho, In-Tak; Han, Sang Youn; Chung, Ha Uk; Lee, Dong Joon; Shin, Jongmin; Baek, Geun Woo; Kim, Tae-il; Lee, Jong-Ho; Rogers, John A

    2015-04-22

    This paper presents device designs, circuit demonstrations, and dissolution kinetics for amorphous indium-gallium-zinc oxide (a-IGZO) thin film transistors (TFTs) comprised completely of water-soluble materials, including SiNx, SiOx, molybdenum, and poly(vinyl alcohol) (PVA). Collections of these types of physically transient a-IGZO TFTs and 5-stage ring oscillators (ROs), constructed with them, show field effect mobilities (∼10 cm2/Vs), on/off ratios (∼2×10(6)), subthreshold slopes (∼220 mV/dec), Ohmic contact properties, and oscillation frequency of 5.67 kHz at supply voltages of 19 V, all comparable to otherwise similar devices constructed in conventional ways with standard, nontransient materials. Studies of dissolution kinetics for a-IGZO films in deionized water, bovine serum, and phosphate buffer saline solution provide data of relevance for the potential use of these materials and this technology in temporary biomedical implants. PMID:25805699

  5. Organic thin-film photovoltaics

    OpenAIRE

    Liu, Miaoyin

    2010-01-01

    Zusammenfassung Zur Verbesserung der Leistungsumwandlung in organischen Solarzellen sind neue Materialien von zentraler Bedeutung, die sämtliche Erfordernisse für organische Photovoltaik-Elemente erfüllen. In der vorliegenden Arbeit „Organic thin-film photovoltaics“ wurden im Hinblick auf ein besseres Verständnis der Zusammenhänge zwischen molekularer Struktur und der Leistungsfähigkeit neue Materialien in „bulk-heterojunction“ Solarzellen und in Festphasen-Farbstoffsensibilisierten ...

  6. Characterizations of photoconductivity of graphene oxide thin films

    Directory of Open Access Journals (Sweden)

    Shiang-Kuo Chang-Jian

    2012-06-01

    Full Text Available Characterizations of photoresponse of a graphene oxide (GO thin film to a near infrared laser light were studied. Results showed the photocurrent in the GO thin film was cathodic, always flowing in an opposite direction to the initial current generated by the preset bias voltage that shows a fundamental discrepancy from the photocurrent in the reduced graphene oxide thin film. Light illumination on the GO thin film thus results in more free electrons that offset the initial current. By examining GO thin films reduced at different temperatures, the critical temperature for reversing the photocurrent from cathodic to anodic was found around 187°C. The dynamic photoresponse for the GO thin film was further characterized through the response time constants within the laser on and off durations, denoted as τon and τoff, respectively. τon for the GO thin film was comparable to the other carbon-based thin films such as carbon nanotubes and graphenes. τoff was, however, much larger than that of the other's. This discrepancy was attributable to the retardation of exciton recombination rate thanks to the existing oxygen functional groups and defects in the GO thin films.

  7. In situ silicon oxide based intermediate reflector for thin-film silicon micromorph solar cells

    OpenAIRE

    Buehlmann, Peter; Bailat, J.; Dominé, Didier; Billet, Adrian; Meillaud, F.; Feltrin, Andrea; Ballif, Christophe

    2008-01-01

    We show that SiO-based intermediate reflectors (SOIRs) can be fabricated in the same reactor and with the same process gases as used for thin-film silicon solar cells. By varying input gas ratios, SOIR layers with a wide range of optical and electrical properties are obtained. The influence of the SOIR thickness in the micromorph cell is studied and current gain and losses are discussed. Initial micromorph cell efficiency of 12.2% (Voc=1.40 V, fill factor=71.9%, and Jsc=12.1 mA/cm2) is achiev...

  8. A Novel Thin Film Resistive Humidity Sensor Based on Soluble Conjugated Polymer: (propionic acid)-co-(propargyl alcohol)

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A novel soluble conjugated copolymer (propionic acid)-co-(propargyl alcohol) (PA-co-OHP) has been synthesized for the first time using a new palladium acetylide catalyst Pd(PPh3)2 (CoCC(CH3)2OH)2 (PPB). Thin film resistive humidity sensor based on the copolymer doped with HClO-4 was prepared. The impedance of the sensor changed from 103~107 W in 95%~30%RH, and the response of that is very quick (<6 sec.). Preliminary results show the copolymer is a promising humidity sensitive material.

  9. Solution-based Syntheses of Iron Pyrite Thin Films for Photovoltaic and Protein Foot-printing Applications

    Science.gov (United States)

    El Makkaoui, Mohammed

    Iron pyrite (cubic FeS2) is a non-toxic, earth abundant semiconductor possessing a set of excellent optical/electronic properties for serving as an absorber layer in PV devices. Additionally, pyrite is a very efficient hydroxyl radical generator via Fenton chemistry and has shown promise in oxidative protein and DNA foot-printing application. The main focus of this thesis is on fabricating phase and elementally pure iron pyrite thin films using a solution-based approach that employs hydrazine as a solvent. A precursor ink is formed at room temperature by mixing elemental iron and sulfur in anhydrous hydrazine and then deposited on Mo-coated glass substrates, via spin coating, to yield amorphous iron sulfide films that are then annealed in H2S (340°C) and sulfur gas (≤ 500 °C) to form uniform, polycrystalline and phase pure pyrite films with densely packed grains. This approach is likely to yield the most elementally pure pyrite thin films made to date, through a very simple and scalable process. The ink has shown to be very sensitive to environmental conditions and has a very short shelf life (˜1 day). Additionally, the film microstructure is greatly influenced by the S:Fe concentration ratio that when tuned to 3:1, yielded uniform, robust and optically flat iron sulfide thin films with an optimal thickness (˜320 nm) for PV application. The results however were not reproducible, mainly due to failure in applying multiple layers without compromising film morphology. Thinner ( 12 hour H2S annealing step, yielded phase pure pyrite films, with good morphology, at lower processing time and annealing temperatures (Albert Einstein College of Medicine and the Khine lab at the University of California, Irvine. A thin film of pyrite nano-crystals is spray deposited (Video in supplementary ) onto a shape memory polymer that is then thermally treated with a heat gun, causing the sheet to retract and stiffen as the nanocrystalline layer crumples and integrates into the

  10. Thin Films Characterization by Ultra Trace Metrology

    International Nuclear Information System (INIS)

    Sensitive and accurate characterization of thin films used in nanoelectronics, thinner than a few nm, represents a challenge for many conventional methods, especially when considering in-line control. With capabilities in the E10 at/cm2 (2O3 tunnel oxide deposited on a magnetic stack. On the other hand, composition analysis by TXRF, and especially the detection of minor elements into thin films, requires the use of a specific incident angle to optimize sensitivity. Under the best conditions, determination of the composition of Co -based self aligned barriers (CoWP and CoWMoPB films with Co concentration >80%) is done with a precision of 6% on P, 8% on Mo and 13% on W (standard deviation)

  11. Synthesis and characterization of three-dimensional transition metal ions doped zinc oxide based dilute magnetic semiconductor thin films

    Science.gov (United States)

    Samanta, Kousik

    Dilute magnetic semiconductors (DMS), especially 3d-transition metal (TM) doped ZnO based DMS materials are the most promising candidates for optoelectronics and spintronics applications; e.g. in spin light emitting diode (SLED), spin transistors, and spin field effect transistors (SFET), etc. In the present dissertation, thin films of Zn1-xTMxO (TM = Co2+, Cu2+, and Mn2+) were grown on (0001) oriented Al2O3 substrates by pulsed laser deposition (PLD) technique. The films were highly c-axis oriented, nearly single crystalline, and defects free for a limited concentration of the dilution of transition metal ions. In particular, we have obtained single crystalline phases of Zn1-xTMxO thin films for up to 10, 3, and 5 stoichiometric percentages of Co2+, Cu2+, and Mn2+ respectively. Raman micro-probe system was used to understand the structural and lattice dynamical properties at different physical conditions. The confinement of optical phonons in the disorder lattice was explained by alloy potential fluctuation (APF) using a spatial correlation (SC) model. The detailed analysis of the optical phonon behavior in disorder lattice confirmed the substitution of the transition metal ions in Zn 2+ site of the ZnO host lattice. The secondary phases of ZnCo 2O4, CuO, and ZnMn2O4 were detected in higher Co, Cu, and Mn doped ZnO thin films respectively; where as, XRD did not detect these secondary phases in the same samples. Room temperature ferromagnetism was observed in Co2+ and Cu2+ ions doped ZnO thin films with maximum saturation magnetization (Ms) of 1.0 and 0.76 muB respectively. The origin of the observed ferromagnetism in Zn1-xCoxO thin films was tested by the controlled introduction of shallow donors (Al) in Zn0.9-x Co0.1O:Alx (x = 0.005 and 0.01) thin films. The saturation magnetization for the 10% Co-doped ZnO (1.0 muB /Co) at 300K reduced (˜0.25 muB/Co) due to Al doping. The observed ferromagnetism and the reduction due to Al doping can be explained by the Bound

  12. Photoconductivity of thin organic films

    International Nuclear Information System (INIS)

    Thin organic films were deposited on silicon oxide surfaces with golden interdigitated electrodes (interelectrode gap was 2 μm), and the film resistivities were measured in dark and under white light illumination. The compounds selected for the measurements include molecules widely used in solar cell applications, such as polythiophene (PHT), fullerene (C60), pyrelene tetracarboxylic diimide (PTCDI) and copper phthalocyanine (CuPc), as well as molecules potentially interesting for photovoltaic applications, e.g. porphyrin-fullerene dyads. The films were deposited using thermal evaporation (e.g. for C60 and CuPc films), spin coating for PHT, and Langmuir-Schaeffer for the layer-by-layer deposition of porphyrin-fullerene dyads. The most conducting materials in the series are films of PHT and CuPc with resistivities 1.2 x 103 Ω m and 3 x 104 Ω m, respectively. Under light illumination resistivity of all films decreases, with the strongest light effect observed for PTCDI, for which resistivity decreases by 100 times, from 3.2 x 108 Ω m in dark to 3.1 x 106 Ω m under the light.

  13. Electrical conduction mechanism in BiFeO3-based ferroelectric thin-film capacitors: Impact of Mn doping

    Directory of Open Access Journals (Sweden)

    Hiroki Matsuo

    2015-12-01

    Full Text Available Electrical conduction properties of SrRuO3(SRO/BiFeO3(BFO/SRO and SRO/10% Mn-doped BFO(BFMO/SRO ferroelectric thin-film capacitors are investigated. The BFO capacitors exhibit a switchable diode effect accompanied by a conduction change from ohmic to space-charge-limited current with increasing external field. In contrast, the BFMO capacitors show only an ohmic conduction, arising from a considerable reduction in depletion layer width at the SRO/BFMO interfaces. These results suggest that the diode property can be tuned by Mn content in the BFO film. Our study opens the possibility of controlling the diode effect in BFO-based devices by a dilute Mn doping.

  14. Eutectic bonds on wafer scale by thin film multilayers

    Science.gov (United States)

    Christensen, Carsten; Bouwstra, Siebe

    1996-09-01

    The use of gold based thin film multilayer systems for forming eutectic bonds on wafer scale is investigated and preliminary results will be presented. On polished 4 inch wafers different multilayer systems are developed using thin film techniques and bonded afterwards under reactive atmospheres and different bonding temperatures and forces. Pull tests are performed to extract the bonding strengths.

  15. Thin film growth of Fe-based superconductors: from fundamental properties to functional devices. A comparative review

    International Nuclear Information System (INIS)

    Fe-based superconductors bridge a gap between MgB2 and the cuprate high temperature superconductors as they exhibit multiband character and transition temperatures up to around 55 K. Investigating Fe-based superconductors thus promises answers to fundamental questions concerning the Cooper pairing mechanism, competition between magnetic and superconducting phases, and a wide variety of electronic correlation effects. The question addressed in this review is, however, is this new class of superconductors also a promising candidate for technical applications? Superconducting film-based technologies range from high-current and high-field applications for energy production and storage to sensor development for communication and security issues and have to meet relevant needs of today's society and that of the future. In this review we will highlight and discuss selected key issues for Fe-based superconducting thin film applications. We initially focus our discussion on the understanding of physical properties and actual problems in film fabrication based on a comparison of different observations made in the last few years. Subsequently we address the potential for technological applications according to the current situation. (review article)

  16. Correlation of film morphology and defect content with the charge-carrier transport in thin-film transistors based on ZnO nanoparticles

    International Nuclear Information System (INIS)

    The correlation of defect content and film morphology with the charge-carrier transport in field-effect devices based on zinc oxide nanoparticles was investigated. Changes in the defect content and the morphology were realized by annealing and sintering of the nanoparticle thin films. Temperature-dependent electrical measurements reveal that the carrier transport is thermally activated for both the unsintered and sintered thin films. Reduced energetic barrier heights between the particles have been determined after sintering. Additionally, the energetic barrier heights between the particles can be reduced by increasing the drain-to-source voltage and the gate-to-source voltage. The changes in the barrier height are discussed with respect to information obtained by scanning electron microscopy and photoluminescence measurements. It is found that a reduction of surface states and a lower roughness at the interface between the particle layer and the gate dielectric lead to lower barrier heights. Both surface termination and layer morphology at the interface affect the barrier height and thus are the main criteria for mobility improvement and device optimization

  17. Correlation of film morphology and defect content with the charge-carrier transport in thin-film transistors based on ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Polster, S. [Chair of Electron Devices, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Cauerstrasse 6, 91058 Erlangen (Germany); Jank, M. P. M. [Fraunhofer Institute for Integrated Systems and Device Technology, Schottkystrasse 10, 91058 Erlangen (Germany); Frey, L. [Chair of Electron Devices, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Cauerstrasse 6, 91058 Erlangen (Germany); Fraunhofer Institute for Integrated Systems and Device Technology, Schottkystrasse 10, 91058 Erlangen (Germany)

    2016-01-14

    The correlation of defect content and film morphology with the charge-carrier transport in field-effect devices based on zinc oxide nanoparticles was investigated. Changes in the defect content and the morphology were realized by annealing and sintering of the nanoparticle thin films. Temperature-dependent electrical measurements reveal that the carrier transport is thermally activated for both the unsintered and sintered thin films. Reduced energetic barrier heights between the particles have been determined after sintering. Additionally, the energetic barrier heights between the particles can be reduced by increasing the drain-to-source voltage and the gate-to-source voltage. The changes in the barrier height are discussed with respect to information obtained by scanning electron microscopy and photoluminescence measurements. It is found that a reduction of surface states and a lower roughness at the interface between the particle layer and the gate dielectric lead to lower barrier heights. Both surface termination and layer morphology at the interface affect the barrier height and thus are the main criteria for mobility improvement and device optimization.

  18. Highly selective single-use fluoride ion optical sensor based on aluminum(III)-salen complex in thin polymeric film

    Energy Technology Data Exchange (ETDEWEB)

    Badr, Ibrahim H.A. [University of Michigan, Department of Chemistry, 930 N. University, Ann Arbor, MI 48105-1055 (United States); Meyerhoff, Mark E. [University of Michigan, Department of Chemistry, 930 N. University, Ann Arbor, MI 48105-1055 (United States)]. E-mail: mmeyerho@umich.edu

    2005-11-30

    A highly selective optical sensor for fluoride ion based on the use of an aluminum(III)-salen complex as an ionophore within a thin polymeric film is described. The sensor is prepared by embedding the aluminum(III)-salen ionophore and a suitable lipophilic pH-sensitive indicator (ETH-7075) in a plasticized poly(vinyl chloride) (PVC) film. Optical response to fluoride occurs due to fluoride extraction into the polymer via formation of a strong complex with the aluminum(III)-salen species. Co-extraction of protons occurs simultaneously, with protonation of the indicator dye yielding the optical response at 529 nm. Films prepared using dioctylsebacate (DOS) are shown to exhibit better response (e.g., linear range, detection limit, and optical signal stability) compared to those prepared using ortho-nitrophenyloctyl ether (o-NPOE). Films formulated with aluminum(III)-salen and ETH-7075 indicator in 2 DOS:1 PVC, exhibit a significantly enhanced selectivity for fluoride over a wide range of lipophilic anions including salicylate, perchlorate, nitrate, and thiocyanate. The optimized films exhibit a sub-micromolar detection limit, using glycine-phosphate buffer, pH 3.00, as the test sample. The response times of the fluoride optical sensing films are in the range of 1-10 min depending on the fluoride ion concentration in the sample. The sensor exhibits very poor reversibility owing to a high co-extraction constant (log K = 8.5 {+-} 0.4), indicating that it can best be employed as a single-use transduction device. The utility of the aluminum(III)-salen based fluoride sensitive films as single-use sensors is demonstrated by casting polymeric films on the bottom of standard polypropylene microtiter plate wells (96 wells/plate). The modified microtiter plate optode format sensors exhibit response characteristics comparable to the classical optode films cast on quartz slides. The modified microtiter is utilized for the analysis of fluoride in diluted anti-cavity fluoride rinse

  19. Effect of film thickness and texture morphology on the physical properties of lead sulfide thin films

    Science.gov (United States)

    Azadi Motlagh, Z.; Azim Araghi, M. E.

    2016-02-01

    Lead sulfide (PbS) thin films were prepared onto ultra-clean quartz substrate by the electron beam gun (EBG) evaporation method. The thicknesses of the thin films were 50, 100, 150 and 200 nm. They were annealed at 423 K for 2 h. Field emission scanning electron microscopy (FESEM) images of the thin films showed their texture morphology at the surface of the quartz substrate. X-ray diffraction (XRD) patterns of the thin films showed that they have a cubic phase and rock-salt structure after annealing. The average crystallite size for the thin films was in the range of 32-100 nm. Optical measurements confirmed that crystalline thin films have a direct band gap that increases by decreasing the film thickness. This blue shift of the band gap of thin films compared to the bulk structure can be attributed to the quantum confinement effects in the nanoparticles. A decrease in conductivity by increasing the temperature confirmed the positive temperature coefficient of resistance in the thin films that showed the dominant conduction mechanism is via a band-like transition. The density of localized states at the Fermi level increases by increasing the film thickness. Current-voltage behavior of the thin films showed an increase in both dark current and photocurrent by increasing the crystallite size which is discussed, based on the presence of trap states and barriers in nanostructures.

  20. Effect of film thickness and texture morphology on the physical properties of lead sulfide thin films

    International Nuclear Information System (INIS)

    Lead sulfide (PbS) thin films were prepared onto ultra-clean quartz substrate by the electron beam gun (EBG) evaporation method. The thicknesses of the thin films were 50, 100, 150 and 200 nm. They were annealed at 423 K for 2 h. Field emission scanning electron microscopy (FESEM) images of the thin films showed their texture morphology at the surface of the quartz substrate. X-ray diffraction (XRD) patterns of the thin films showed that they have a cubic phase and rock-salt structure after annealing. The average crystallite size for the thin films was in the range of 32–100 nm. Optical measurements confirmed that crystalline thin films have a direct band gap that increases by decreasing the film thickness. This blue shift of the band gap of thin films compared to the bulk structure can be attributed to the quantum confinement effects in the nanoparticles. A decrease in conductivity by increasing the temperature confirmed the positive temperature coefficient of resistance in the thin films that showed the dominant conduction mechanism is via a band-like transition. The density of localized states at the Fermi level increases by increasing the film thickness. Current–voltage behavior of the thin films showed an increase in both dark current and photocurrent by increasing the crystallite size which is discussed, based on the presence of trap states and barriers in nanostructures. (paper)

  1. {sup 57}Fe Moessbauer studies of Fe-Si based amorphous ferromagnetic ribbons and thin films

    Energy Technology Data Exchange (ETDEWEB)

    Aghamohammadzadeh, H

    1998-04-01

    {sup 57}Fe Moessbauer Spectroscopy has been used to study the mean magnetic moment direction and the distribution of moment directions in ribbon and thin film of amorphous ferromagnets known as Metglass and Finemet. We have studied them in As Received (AR) and Stress Relieved (SR) or Heat Treated (HT) states. These samples are excellent 'soft magnetic materials' with low coercivity of 8 A/m and 0.5 A/m respectively. Annealing has different effects on these samples. Although following annealing coercivity decreases for both Metglass and Finemet samples, in the Finemet it creates a second phase of DO{sub 3} structure which is a nanocrystallite. Our analysis also shows that in the Heat Treated Finemet ribbon 34 % (vol.) of the sample is amorphous and 64 % (vol.) nanocrystalline. In the HT Finemet there are seven different iron sites of which 6 sites belong to the crystalline phase and one site to the amorphous phase. We have studied the distribution of the hyperfine fields, which cause broadening of the spectral lines in the amorphous state. Each iron site has a different environment which is in turn the reason for the field distribution.Our results show that following annealing the mean magnetic field decreases from about 211 kOe in the AR Finemet to 165 kOe in the amorphous phase of the heat treated Finemet which means in this phase there is a depletion in the iron atoms. The spectra were recorded for a range of inclinations between the {gamma}-rays and the normal to the sample plane. Different phenomenological models have been used to investigate the moment direction distribution (anisotropy) in our sample. The results show that in both Metglass and Finemet samples annealing decreases the in-plane anisotropy substantially but not the out-of-plane anisotropy. We also show that the properties of Metglass thin film are quite different from its ribbon sample. Low temperature studies of the Metglass Ribbon sample allow us to investigate the temperature

  2. 57Fe Moessbauer studies of Fe-Si based amorphous ferromagnetic ribbons and thin films

    International Nuclear Information System (INIS)

    57Fe Moessbauer Spectroscopy has been used to study the mean magnetic moment direction and the distribution of moment directions in ribbon and thin film of amorphous ferromagnets known as Metglass and Finemet. We have studied them in As Received (AR) and Stress Relieved (SR) or Heat Treated (HT) states. These samples are excellent 'soft magnetic materials' with low coercivity of 8 A/m and 0.5 A/m respectively. Annealing has different effects on these samples. Although following annealing coercivity decreases for both Metglass and Finemet samples, in the Finemet it creates a second phase of DO3 structure which is a nanocrystallite. Our analysis also shows that in the Heat Treated Finemet ribbon 34 % (vol.) of the sample is amorphous and 64 % (vol.) nanocrystalline. In the HT Finemet there are seven different iron sites of which 6 sites belong to the crystalline phase and one site to the amorphous phase. We have studied the distribution of the hyperfine fields, which cause broadening of the spectral lines in the amorphous state. Each iron site has a different environment which is in turn the reason for the field distribution. Our results show that following annealing the mean magnetic field decreases from about 211 kOe in the AR Finemet to 165 kOe in the amorphous phase of the heat treated Finemet which means in this phase there is a depletion in the iron atoms. The spectra were recorded for a range of inclinations between the γ-rays and the normal to the sample plane. Different phenomenological models have been used to investigate the moment direction distribution (anisotropy) in our sample. The results show that in both Metglass and Finemet samples annealing decreases the in-plane anisotropy substantially but not the out-of-plane anisotropy. We also show that the properties of Metglass thin film are quite different from its ribbon sample. Low temperature studies of the Metglass Ribbon sample allow us to investigate the temperature dependence of the moment

  3. Preparation of thin film gold based catalysts for oxidation reactions in liquid and gas phases

    International Nuclear Information System (INIS)

    This work deals with the preparation of gold on titania catalysts to make catalytic films in the less than 100 nm thickness area and its comparison with usual powder catalyst in catalytic oxidation reactions in gas and liquid phases. Titania was coated on glass plates with different thicknesses, but with ultra-low surface roughness (< 5 Å). Gold deposition was performed with usual chemical method for catalysts preparation, that is deposition–precipitation with urea. Transmission electron microscopy showed that planar samples are decorated with a high quantity (> 10 wt.% with respect to TiO2) of gold nanoparticles smaller than 2.5 nm, with a narrow size distribution. Activity in CO oxidation demonstrates the catalytic behavior of the planar samples, although they are less active than powder catalyst because of the different geometries of the reactors and catalysts. In contrast, their catalytic performances in liquid phase, benzyl alcohol oxidation, are comparable. These results validate the concept that gold planar catalysts prepared by chemical methods can present similar catalytic behavior as real powder gold catalysts. Such planar catalysts could be useful for bridging the material gap between real and model catalysts in advanced techniques, such as scanning tunnelling microscopy and spectroscopy or high-pressure photoelectron spectroscopy. - Highlights: ► Preparation of thin film of TiO2 (pure anatase) on glass with a low roughness (< 5 Å) ► High density of small gold nanoparticles on planar substrates by a chemical method ► Planar catalysts active in both gas and liquid phase oxidation reactions ► Bridging of the material gap between real and model catalysts

  4. Development of Thin Film Amorphous Silicon Tandem Junction Based Photocathodes Providing High Open-Circuit Voltages for Hydrogen Production

    Directory of Open Access Journals (Sweden)

    F. Urbain

    2014-01-01

    Full Text Available Hydrogenated amorphous silicon thin film tandem solar cells (a-Si:H/a-Si:H have been developed with focus on high open-circuit voltages for the direct application as photocathodes in photoelectrochemical water splitting devices. By temperature variation during deposition of the intrinsic a-Si:H absorber layers the band gap energy of a-Si:H absorber layers, correlating with the hydrogen content of the material, can be adjusted and combined in a way that a-Si:H/a-Si:H tandem solar cells provide open-circuit voltages up to 1.87 V. The applicability of the tandem solar cells as photocathodes was investigated in a photoelectrochemical cell (PEC measurement set-up. With platinum as a catalyst, the a-Si:H/a-Si:H based photocathodes exhibit a high photocurrent onset potential of 1.76 V versus the reversible hydrogen electrode (RHE and a photocurrent of 5.3 mA/cm2 at 0 V versus RHE (under halogen lamp illumination. Our results provide evidence that a direct application of thin film silicon based photocathodes fulfills the main thermodynamic requirements to generate hydrogen. Furthermore, the presented approach may provide an efficient and low-cost route to solar hydrogen production.

  5. A comparative study on the performance of Kesterite based thin film solar cells using SCAPS simulation program

    Science.gov (United States)

    Simya, O. K.; Mahaboobbatcha, A.; Balachander, K.

    2015-06-01

    A comparative study of thin film solar cells based on CZTS, CZTSe, and CZTSSe (Copper Zinc Tin Sulphur Selenium) absorbers layers were simulated with Cadmium Sulphide (CdS) as buffer layer and Zinc Oxide (ZnO) as window layer using a solar cell capacitance simulator (SCAPS). The influences of series resistance, band to band recombination, defects and interfaces, thickness of (CZTS|CZTSe|CZTSSe) absorber layer, (CdS) buffer layer and transparent conductive oxide layer (ZnO) on the photovoltaic cell parameters were studied in detail. Improvements in efficiency were achieved by changing the back contact metal work function (BMWF) and choosing the flat band option in SCAPS software. Based on the best possible optimisation, an efficiency (η) of 12.03%, 13.16% and 15.77% were obtained for CZTS, CZTSe, and CZTSSe respectively. The performance of thin film photovoltaic devices (TFPV), for Mo back contact before optimisation and the SCAPS simulated values (flat band) after optimisation were described in detail to have in-depth understanding for better design of experiments (DOE) to obtain high efficiency solar cells.

  6. Remarkable reduction in the threshold voltage of pentacene-based thin film transistors with pentacene/CuPc sandwich configuration

    Directory of Open Access Journals (Sweden)

    Yi Li

    2014-06-01

    Full Text Available This study investigates the remarkable reduction in the threshold voltage (VT of pentacene-based thin film transistors with pentacene/copper phthalocyanine (CuPc sandwich configuration. This reduction is accompanied by increased mobility and lowered sub-threshold slope (S. Sandwich devices coated with a 5 nm layer of CuPc layer are compared with conventional top-contact devices, and results indicate that VT decreased significantly from −20.4 V to −0.2 V, that mobility increased from 0.18 cm2/Vs to 0.51 cm2/Vs, and that S was reduced from 4.1 V/dec to 2.9 V/dec. However, the on/off current ratio remains at 105. This enhanced performance could be attributed to the reduction in charge trap density by the incorporated CuPc layer. Results suggest that this method is simple and effectively generates pentacene-based organic thin film transistors with high mobility and low VT.

  7. Electrical characterisation of ferroelectric field effect transistors based on ferroelectric HfO{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Yurchuk, Ekaterina

    2015-02-06

    Ferroelectric field effect transistor (FeFET) memories based on a new type of ferroelectric material (silicon doped hafnium oxide) were studied within the scope of the present work. Utilisation of silicon doped hafnium oxide (Si:HfO{sub 2}) thin films instead of conventional perovskite ferroelectrics as a functional layer in FeFETs provides compatibility to the CMOS process as well as improved device scalability. The influence of different process parameters on the properties of Si:HfO{sub 2} thin films was analysed in order to gain better insight into the occurrence of ferroelectricity in this system. A subsequent examination of the potential of this material as well as its possible limitations with the respect to the application in non-volatile memories followed. The Si:HfO{sub 2}-based ferroelectric transistors that were fully integrated into the state-of-the-art high-k metal gate CMOS technology were studied in this work for the first time. The memory performance of these devices scaled down to 28 nm gate length was investigated. Special attention was paid to the charge trapping phenomenon shown to significantly affect the device behaviour.

  8. Stable, high-efficiency, CuInSe2-based, polycrystalline, thin-film tandem solar cells

    Science.gov (United States)

    Birkmire, R. W.; Phillips, J. E.

    1987-10-01

    The long-term objective of this research was to obtain a stable, thin-film solar cell based on polycrystalline materials with an efficiency of 15 percent. The approach was to make a tandem cell based on CuInSe2/CdS as the bottom cell and CdTe/CdS as the top cell. An essential feature was to develop a CdTe cell with transport contacts. A suitable contacting system was developed using transparent conducting oxides (ITO and SnO2) in conjunction with a thin layer of copper. Cells were made with efficiencies over 8.5 percent. A reproducible fabrication process for CuInSe2/(CdZn)S cells was developed based on CuInSe2 films grown by vacuum evaporation using Knudsen-type effusion sources. These cells were made with efficiencies over 10 percent. The composition of the CuInSe2 films can be varied over a considerable range and still yield high-efficiency cells. Adding Zn to the CdS did not increase the V(sub oc) of the devices; analysis showed that the V(sub oc) is not controlled by interface recombination. The effect of oxidizing and reducing heat treatments on CuInSe2 cells is to change carrier concentration and thus V(sub oc). Analysis suggests that J(sub o) is controlled by band-to-band recombination. Monolithic tandem CuInSe2 CdTe cells have been made with efficiencies of approximately 3 percent, demonstrating the feasibility of this approach.

  9. Flexible Tactile Sensor Using Polyurethane Thin Film

    OpenAIRE

    Seiji Aoyagi; Tomokazu Takahashi; Masato Suzuki

    2012-01-01

    A novel capacitive tactile sensor using a polyurethane thin film is proposed in this paper. In previous studies, capacitive tactile sensors generally had an air gap between two electrodes in order to enhance the sensitivity. In this study, there is only polyurethane thin film and no air gap between the electrodes. The sensitivity of this sensor is higher than the previous capacitive tactile sensors because the polyurethane is a fairly flexible elastomer and the film is very thin (about 1 µm)....

  10. Wireless thin film transistor based on micro magnetic induction coupling antenna

    Science.gov (United States)

    Jun, Byoung Ok; Lee, Gwang Jun; Kang, Jong Gu; Kim, Seunguk; Choi, Ji-Woong; Cha, Seung Nam; Sohn, Jung Inn; Jang, Jae Eun

    2015-12-01

    A wireless thin film transistor (TFT) structure in which a source/drain or a gate is connected directly to a micro antenna to receive or transmit signals or power can be an important building block, acting as an electrical switch, a rectifier or an amplifier, for various electronics as well as microelectronics, since it allows simple connection with other devices, unlike conventional wire connections. An amorphous indium gallium zinc oxide (α-IGZO) TFT with magnetic antenna structure was fabricated and studied for this purpose. To enhance the induction coupling efficiency while maintaining the same small antenna size, a magnetic core structure consisting of Ni and nanowires was formed under the antenna. With the micro-antenna connected to a source/drain or a gate of the TFT, working electrical signals were well controlled. The results demonstrated the device as an alternative solution to existing wire connections which cause a number of problems in various fields such as flexible/wearable devices, body implanted devices, micro/nano robots, and sensors for the ‘internet of things’ (IoT).

  11. Flexible gastrointestinal motility pressure sensors based on aluminum thin-film strain-gauge arrays

    International Nuclear Information System (INIS)

    This paper reports on an innovative approach to measuring intraluminal pressure in the upper gastrointestinal (GI) tract, especially monitoring GI motility and peristaltic movements. The proposed approach relies on thin-film aluminum strain gauges deposited on top of a Kapton membrane, which in turn lies on top of an SU-8 diaphragm-like structure. This structure enables the Kapton membrane to bend when pressure is applied, thereby affecting the strain gauges and effectively changing their electrical resistance. The sensor, with an area of 3.4 mm2, is fabricated using photolithography and standard microfabrication techniques (wet etching). It features a linear response (R2 = 0.9987) and an overall sensitivity of 2.6 mV mmHg−1. Additionally, its topology allows a high integration capability. The strain gauges’ responses to pressure were studied and the fabrication process optimized to achieve high sensitivity, linearity, and reproducibility. The sequential acquisition of the different signals is carried out by a microcontroller, with a 10-bit ADC and a sample rate of 250 Hz. The pressure signals are then presented in a user-friendly interface, developed using the Integrated Development Environment software, QtCreator IDE, for better visualization by physicians. (paper)

  12. Fundamentals of photoelectric effects in molecular electronic thin film devices: applications to bacteriorhodopsin-based devices.

    Science.gov (United States)

    Hong, F T

    1995-01-01

    This tutorial lecture focuses on the fundamental mechanistic aspects of light-induced charge movements in pigment-containing membranes. The topic is relevant to molecular electronics because many prototypes optoelectronic devices are configured as pigment-containing thin films. We use reconstituted bacteriorhodopsin membranes as an example to illustrate the underlying principle of measurements and data interpretation. Bacteriorhodopsin, a light-driven proton pump, is the only protein component in the purple membrane of Halobacterium halobium. It resembles the visual pigment rhodopsin chemically but performs the function of photosynthesis. Bacteriorhodopsin thus offers an unprecedented opportunity for us to compare the visual photoreceptor and the photosynthetic apparatus from a mechanistic point of view. Bacteriorhodopsin, well known for its exceptional chemical and mechanical stability, is also a popular advanced biomaterial for molecular device construction. The tutorial approaches the subject from two angles. First, the fundamental photoelectric properties are exploited for device construction. Second, basic design principles for photosensors and photon energy converters can be elucidated via 'reverse engineering'. The concept of molecular intelligence and the principle of biomimetic science are discussed.

  13. Liquid crystal devices with continuous phase variation based on high-permittivity thin films

    Science.gov (United States)

    Willekens, Oliver; Neyts, Kristiaan; Beeckman, Jeroen

    2016-03-01

    Most liquid crystal devices use transparent conductive electrodes such as indium tin oxide (ITO) to apply a potential difference in order to achieve electro-optic switching. As an alternative, we study a device with narrow metallic electrodes in combination with dielectric layers with large dielectric permittivity. In this approach the applied voltage can be a continuous function of the lateral distance from the electrode line. Simulations for a one-dimensional beam-steering device show that the switching of the liquid crystal (LC) director depends indeed on the distance from the addressing electrodes and on the value of the relative permittivity. We show that in a device with electrodes spaced 60 µm apart, the LC director halfway between the electrodes shows a considerable reorientation, when a dielectric layer with permittivity of Epsilonr = 550 is used, whereas no reorientation is observed for the uncoated reference sample at the same voltage. An added advantage is that the proposed configuration only contains dielectric materials, without resistive losses, which means that almost no heat is dissipated. This indicates that this technology could be used in low-power LC devices. The results show that using dielectric thin films with high relative permittivity in liquid crystal devices could form a cost-efficient and low-power alternative to many LC technologies where a gradient electric field is desirable.

  14. Transparent Thin Film Transistors based on Pristine and Doped Indium Oxide Nanowires

    Science.gov (United States)

    Chen, Po-Chiang; Shen, Guozhen; Sukcharoenchoke, Saowalak; Zhou, Chongwu

    2009-03-01

    The key to the realization of transparent electronics is the development of transparent thin film transistors (TTFT) with good device performance, in terms of high device mobility, low temperature fabrication, and optical transparency. We present our work on the fabrication of high performance TTFTs using both pristine In2O3 nanowires and doped In2O3 nanowires. In2O3 nanowire TTFTs were made on glass and PET substrates with Al2O3 as gate insulator and ITO source/drain electrodes. These devices showed a transparency of about 80% and n-type transistor performance. The device characteristics exhibit a subthreshold slope of 0.2 V/dec, a current on/off ratio of 10^6, and a field-effect mobility of 514 cm^2V-1S-1. We also fabricated TTFTs wbuilt on Arsenic-doped In2O3 nanowires with a field-effect mobility of 1,183.8 cm^2V-1S-1 without any post-treatments. In addition, we integrated TTFTs with organic light emitting diode (OLED) to make an active matrix organic light emitting diode (AMOLED) display, and thus made an animation by controlling the OLED light output.

  15. Thermoviscoelastic models for polyethylene thin films

    DEFF Research Database (Denmark)

    Li, Jun; Kwok, Kawai; Pellegrino, Sergio

    2016-01-01

    This paper presents a constitutive thermoviscoelastic model for thin films of linear low-density polyethylene subject to strains up to yielding. The model is based on the free volume theory of nonlinear thermoviscoelasticity, extended to orthotropic membranes. An ingredient of the present approach...... is that the experimentally inaccessible out-of-plane material properties are determined by fitting the model predictions to the measured nonlinear behavior of the film. Creep tests, uniaxial tension tests, and biaxial bubble tests are used to determine the material parameters. The model has been validated experimentally...

  16. Photovoltaic enhancement based on improvement of ferroelectric property and band gap in Ti-doped bismuth ferrite thin films

    International Nuclear Information System (INIS)

    Highlights: • The leakage current is effectively reduced by adding a certain amount of titanium. • Addition of titanium increases the remnant polarization and decreases the band gap. • The power conversion efficiency increases as titanium content increases. - Abstract: Ti-doped bismuth ferrite thin films were prepared via sol–gel spin-coating method. The effects of titanium on the microstructure, optical, leakage, ferroelectric and photovoltaic characteristics have been investigated systematically. The result shows that bismuth ferrite thin films doped with 0–8 at.% Ti are rhombohedral distortion perovskite structure. The addition of titanium inhibits the grain growth and enhances the thickness uniformity and can decrease the band gap of bismuth ferrite thin films. The leakage current of bismuth ferrite thin films is effectively reduced by adding a certain amount of titanium and the leakage mechanism has been investigated. Addition of titanium increases the remnant polarization of the films. As titanium content increases, the short circuit photocurrent density decrease first and then increase, while the open circuit photovoltage increase first and then decrease. The power conversion efficiency of Ti-doped bismuth ferrite thin films increases as titanium content increases, which can be explained as a result of the increased remnant polarization and decreased band gap

  17. Thin films for emerging applications v.16

    CERN Document Server

    Francombe, Maurice H

    1992-01-01

    Following in the long-standing tradition of excellence established by this serial, this volume provides a focused look at contemporary applications. High Tc superconducting thin films are discussed in terms of ion beam and sputtering deposition, vacuum evaporation, laser ablation, MOCVD, and other deposition processes in addition to their ultimate applications. Detailed treatment is also given to permanent magnet thin films, lateral diffusion and electromigration in metallic thin films, and fracture and cracking phenomena in thin films adhering to high-elongation substrates.

  18. Polycrystalline thin film materials and devices

    Energy Technology Data Exchange (ETDEWEB)

    Baron, B.N.; Birkmire, R.W.; Phillips, J.E.; Shafarman, W.N.; Hegedus, S.S.; McCandless, B.E. (Delaware Univ., Newark, DE (United States). Inst. of Energy Conversion)

    1992-10-01

    Results of Phase II of a research program on polycrystalline thin film heterojunction solar cells are presented. Relations between processing, materials properties and device performance were studied. The analysis of these solar cells explains how minority carrier recombination at the interface and at grain boundaries can be reduced by doping of windows and absorber layers, such as in high efficiency CdTe and CuInSe{sub 2} based solar cells. The additional geometric dimension introduced by the polycrystallinity must be taken into consideration. The solar cells are limited by the diode current, caused by recombination in the space charge region. J-V characteristics of CuInSe{sub 2}/(CdZn)S cells were analyzed. Current-voltage and spectral response measurements were also made on high efficiency CdTe/CdS thin film solar cells prepared by vacuum evaporation. Cu-In bilayers were reacted with Se and H{sub 2}Se gas to form CuInSe{sub 2} films; the reaction pathways and the precursor were studied. Several approaches to fabrication of these thin film solar cells in a superstrate configuration were explored. A self-consistent picture of the effects of processing on the evolution of CdTe cells was developed.

  19. High Electron Mobility Thin-Film Transistors Based on Solution-Processed Semiconducting Metal Oxide Heterojunctions and Quasi-Superlattices

    KAUST Repository

    Lin, Yen-Hung

    2015-05-26

    High mobility thin-film transistor technologies that can be implemented using simple and inexpensive fabrication methods are in great demand because of their applicability in a wide range of emerging optoelectronics. Here, a novel concept of thin-film transistors is reported that exploits the enhanced electron transport properties of low-dimensional polycrystalline heterojunctions and quasi-superlattices (QSLs) consisting of alternating layers of In2O3, Ga2O3, and ZnO grown by sequential spin casting of different precursors in air at low temperatures (180–200 °C). Optimized prototype QSL transistors exhibit band-like transport with electron mobilities approximately a tenfold greater (25–45 cm2 V−1 s−1) than single oxide devices (typically 2–5 cm2 V−1 s−1). Based on temperature-dependent electron transport and capacitance-voltage measurements, it is argued that the enhanced performance arises from the presence of quasi 2D electron gas-like systems formed at the carefully engineered oxide heterointerfaces. The QSL transistor concept proposed here can in principle extend to a range of other oxide material systems and deposition methods (sputtering, atomic layer deposition, spray pyrolysis, roll-to-roll, etc.) and can be seen as an extremely promising technology for application in next-generation large area optoelectronics such as ultrahigh definition optical displays and large-area microelectronics where high performance is a key requirement.

  20. A Micro Oxygen Sensor Based on a Nano Sol-Gel TiO2 Thin Film

    Directory of Open Access Journals (Sweden)

    Hairong Wang

    2014-09-01

    Full Text Available An oxygen gas microsensor based on nanostructured sol-gel TiO2 thin films with a buried Pd layer was developed on a silicon substrate. The nanostructured titania thin films for O2 sensors were prepared by the sol-gel process and became anatase after heat treatment. A sandwich TiO2 square board with an area of 350 μm × 350 μm was defined by both wet etching and dry etching processes and the wet one was applied in the final process due to its advantages of easy control for the final structure. A pair of 150 nm Pt micro interdigitated electrodes with 50 nm Ti buffer layer was fabricated on the board by a lift-off process. The sensor chip was tested in a furnace with changing the O2 concentration from 1.0% to 20% by monitoring its electrical resistance. Results showed that after several testing cycles the sensor’s output becomes stable, and its sensitivity is 0.054 with deviation 2.65 × 10−4 and hysteresis is 8.5%. Due to its simple fabrication process, the sensor has potential for application in environmental monitoring, where lower power consumption and small size are required.

  1. Minerals deposited as thin films

    International Nuclear Information System (INIS)

    Free matrix effects are due to thin film deposits. Thus, it was decided to investigate this technique as a possibility to use pure oxide of the desired element, extrapolating its concentration from analytical curves made with avoiding, at the same time, mathematical corrections. The proposed method was employed to determine iron and titanium concentrations in geological samples. The range studied was 0.1-5%m/m for titanium and 5-20%m/m for iron. For both elements the reproducibility was about 7% and differences between this method and other chemical determinations were 15% for titanium and 7% for iron. (Author)

  2. Interactions in thin aqueous films

    OpenAIRE

    Hänni-Ciunel, Katarzyna

    2006-01-01

    In der Arbeit werden die Wechselwirkungen in dünnen flüssigen Filmen untersucht und modifiziert. Schaum- (gas/flüssig/gas) und Benetzungsfilme (gas/flüssig/fest) werden mittels Thin Film Pressure Balance (TFPB) untersucht. Die Apparatur wurde im Rahmen der Arbeit für die Studien an asymmetrischen Filmen aufgebaut und modifiziert. Die Ladungen an den Filmgrenzflächen werden gezielt modifiziert. Die Adsoprtion von Tensiden bestimmt die Oberflächenladung an der gas/flüssig Grenzfläche. Die Oberf...

  3. The role of thin films in wetting

    OpenAIRE

    Marmur, Abraham

    1988-01-01

    The role of thin films in wetting is reviewed. Three modes of spontaneous spreading are discussed : incomplete spreading, complete spreading and mixed-mode spreading. A thin film can be either molecular or colloidal in thickness. Molecularly adsorbed films are mainly associated with incomplete spreading. Colloidal films usually extend from the bulk of the liquid in dynamic situations of complete spreading. Their existence at equilibriuim with the bulk depends on the orientation in the gravita...

  4. Facile encapsulation of oxide based thin film transistors by atomic layer deposition based on ozone.

    Science.gov (United States)

    Fakhri, Morteza; Babin, Nikolai; Behrendt, Andreas; Jakob, Timo; Görrn, Patrick; Riedl, Thomas

    2013-05-28

    A simplified encapsulation strategy for metal-oxide based TFTs, using ozone instead of water as an oxygen source in a low-temperature ALD process is demonstrated. Thereby, the threshold voltage remains unaltered and the hysteresis is permanently reduced. Costly energy- and time-consuming post-treatment processes can be avoided. This concept is widely applicable to various encapsulation materials (e.g., Al2 O3 , TiO2 , ZrO2 ) and metal-oxide channel semiconductors (e.g., zinc-tin-oxide (ZTO), indium-gallium-zinc-oxide (IGZO)).

  5. Nanotwin hardening in a cubic chromium oxide thin film

    Directory of Open Access Journals (Sweden)

    Kazuma Suzuki

    2015-09-01

    Full Text Available NaCl-type (B1 chromium oxide (CrO has been expected to have a high hardness value and does not exist as an equilibrium phase. We report a B1-based Cr0.67O thin film with a thickness of 144 nm prepared by pulsed laser deposition as an epitaxial thin film on a MgO single crystal. The thin film contained a number of stacking faults and had a nanotwinned structure composed of B1 with disordered vacancies and corundum structures. The Cr0.67O thin film had a high indentation hardness value of 44 GPa, making it the hardest oxide thin film reported to date.

  6. Microstructural evolution of tungsten oxide thin films

    International Nuclear Information System (INIS)

    Tungsten oxide thin films are of great interest due to their promising applications in various optoelectronic thin film devices. We have investigated the microstructural evolution of tungsten oxide thin films grown by DC magnetron sputtering on silicon substrate. The structural characterization and surface morphology were carried out using X-ray diffraction and Scanning Electron Microscopy (SEM). The as deposited films were amorphous, where as, the films annealed above 400 deg. were crystalline. In order to explain the microstructural changes due to annealing, we have proposed a 'instability wheel' model for the evolution of the microstructure. This model explains the transformation of mater into various geometries within them selves, followed by external perturbation.

  7. ENERGY EFFICIENCY OF A PHOTOVOLTAIC CELL BASED THIN FILMS CZTS BY SCAPS

    OpenAIRE

    C. Mebarkiaa; Dib, D. (collab.); H. Zerfaoui; R. Belghit

    2016-01-01

    In the overall context of the diversification of the use of natural resources, the use of renewable energy including solar photovoltaic has become increasingly indispensable. As such, the development of a new generation of photovoltaic cells based on CuZnSnS4 (CZTS) looks promising. Cu2ZnSnS4 (CZTS) is a new film absorber, with good physical properties (band gap energy 1.4-1.6 eV [01] with a large absorption coefficient over 104 cm-1). Indeed, the performance of these cells exceeded 30% in re...

  8. Data storage applications based on LiCoO2 thin films grown on Al2O3 and Si substrates

    Science.gov (United States)

    Svoukis, E.; Mihailescu, C. N.; Mai, V. H.; Schneegans, O.; Breza, K.; Lioutas, C.; Giapintzakis, J.

    2016-09-01

    In this study, LiCoO2 thin films were investigated for data storage applications based on scanning probe mediated approaches. LiCoO2, compared to other materials proposed for scanning probe mediated nanoscale patterning, is highly stable and exhibits reversible electrochemical surface modifications. LiCoO2 thin films have been grown by pulsed laser deposition on Al2O3 and Si substrates over a range of deposition temperatures. The crystal structure and the microstructure of the films has been inferred through in- and out-of-plane X-ray diffraction studies and high-resolution transmission electron microscopy, respectively. The influence of the film deposition temperature on the surface electrical properties of the LiCoO2 films is discussed along with the relevant mechanism of surface resistance modification.

  9. Wavelength-switchable multiwavelength erbium-doped fiber laser based on a D-shaped fiber with a photoresist thin-film overlay

    International Nuclear Information System (INIS)

    A wavelength-switchable multiwavelength erbium-doped fiber (EDF) laser based on a D-shaped fiber with a photoresist (PR) thin-film overlay is proposed and experimentally demonstrated. The D-shaped fiber with a PR thin-film overlay is implemented as a multichannel filter. Based on the evanescent field coupling between the D-shaped fiber and the PR thin-film overlay, periodic transmission characteristics are obtained. The wavelength spacing of the D-shaped fiber with the PR thin-film overlay is controlled by changing the thickness and the refractive index of the PR thin film overlay. By inserting the proposed multichannel filter into an EDF ring laser, a multiwavelength EDF laser is achieved. The homogenous line broadening of erbium ions for the realization of stable operation of the multiwavelength EDF ring laser is suppressed by using a nonlinear polarization rotation. A high-quality multiwavelength output with a high extinction ratio of ∼0 dB is realized. The output fluctuation of the proposed multiwavelength EDF ring laser is measured to be less than 0.3 dB. Since the transmission characteristics of the proposed multichannel filter are controlled by using two orthogonal input polarization states, multiwavelength lasing outputs are switched.

  10. A versatile platform for magnetostriction measurements in thin films

    Science.gov (United States)

    Pernpeintner, M.; Holländer, R. B.; Seitner, M. J.; Weig, E. M.; Gross, R.; Goennenwein, S. T. B.; Huebl, H.

    2016-03-01

    We present a versatile nanomechanical sensing platform for the investigation of magnetostriction in thin films. It is based on a doubly clamped silicon nitride nanobeam resonator covered with a thin magnetostrictive film. Changing the magnetization direction within the film plane by an applied magnetic field generates a magnetoelastic stress and thus changes the resonance frequency of the nanobeam. A measurement of the resulting resonance frequency shift, e.g., by optical interferometry, allows to quantitatively determine the magnetostriction constants of the thin film. In a proof-of-principle experiment, we determine the magnetostriction constants of a 10 nm thick polycrystalline cobalt film, showing very good agreement with literature values. The presented technique aims, in particular, for the precise measurement of magnetostriction in a variety of (conducting and insulating) thin films, which can be deposited by, e.g., electron beam deposition, thermal evaporation, or sputtering.

  11. Thin liquid films dewetting and polymer flow

    CERN Document Server

    Blossey, Ralf

    2012-01-01

    This book is a treatise on the thermodynamic and dynamic properties of thin liquid films at solid surfaces and, in particular, their rupture instabilities. For the quantitative study of these phenomena, polymer thin films haven proven to be an invaluable experimental model system.   What is it that makes thin film instabilities special and interesting, warranting a whole book? There are several answers to this. Firstly, thin polymeric films have an important range of applications, and with the increase in the number of technologies available to produce and to study them, this range is likely to expand. An understanding of their instabilities is therefore of practical relevance for the design of such films.   Secondly, thin liquid films are an interdisciplinary research topic. Interdisciplinary research is surely not an end to itself, but in this case it leads to a fairly heterogeneous community of theoretical and experimental physicists, engineers, physical chemists, mathematicians and others working on the...

  12. The influence of nitrogen and oxygen additions on the thermal characteristics of aluminium-based thin films

    Energy Technology Data Exchange (ETDEWEB)

    Borges, J., E-mail: joelborges@fisica.uminho.pt [Centro de Física, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Department of Control Engineering, Faculty of Electrical Engineering, Czech Technical University in Prague, Technická 2, Prague 6 (Czech Republic); Macedo, F. [Centro de Física, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Couto, F.M. [Physics Sciences Laboratory, Norte Fluminense State University, 28013-602 Campos–RJ (Brazil); Rodrigues, M.S.; Lopes, C. [Centro de Física, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Instituto Pedro Nunes, Laboratório de Ensaios, Desgaste e Materiais, Rua Pedro Nunes, 3030-199 Coimbra (Portugal); Pedrosa, P. [Centro de Física, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); SEG-CEMUC, Mechanical Engineering Department, University of Coimbra, 3030-788 Coimbra (Portugal); Universidade do Porto, Faculdade de Engenharia, Departamento de Engenharia Metalúrgica e de Materiais, Rua Dr. Roberto Frias, s/n, 4200-465 Porto (Portugal); Polcar, T. [Department of Control Engineering, Faculty of Electrical Engineering, Czech Technical University in Prague, Technická 2, Prague 6 (Czech Republic); Engineering Materials & nCATS, FEE, University of Southampton, Highfield Campus, SO17 1BJ, Southampton (United Kingdom); Marques, L.; Vaz, F. [Centro de Física, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal)

    2015-08-01

    The ternary aluminium oxynitride (AlN{sub x}O{sub y}) system offers the possibility to obtain a wide range of properties by tailoring the ratio between pure Al, AlN{sub x} and AlO{sub y} and therefore opening a significant number of possible applications. In this work the thermal behaviour of AlN{sub x}O{sub y} thin films was analysed by modulated infrared radiometry (MIRR), taking as reference the binary AlO{sub y} and AlN{sub x} systems. MIRR is a non-contact and non-destructive thermal wave measurement technique based on the excitation, propagation and detection of temperature oscillations of very small amplitudes. The intended change of the partial pressure of the reactive gas (N{sub 2} and/or O{sub 2}) influenced the target condition and hence the deposition characteristics which, altogether, affected the composition and microstructure of the films. Based on the MIRR measurements and their qualitative and quantitative interpretation, some correlations between the thermal transport properties of the films and their chemical/physical properties have been found. Furthermore, the potential of such technique applied in this oxynitride system, which present a wide range of different physical responses, is also discussed. The experimental results obtained are consistent with those reported in previous works and show a high potential to fulfil the demands needed for the possible applications of the systems studied. They are clearly indicative of an adequate thermal response if this particular thin film system is aimed to be applied in small sensor devices or in electrodes for biosignal acquisition, such as those for electroencephalography or electromyography as it is the case of the main research area that is being developed in the group. - Highlights: • AlN{sub x}, AlO{sub y} and AlN{sub x}O{sub y} films were deposited by magnetron sputtering. • Discharge characteristics were compared between systems. • Different x and y coefficients were obtained.

  13. CuIn(S,Se)(2) thin films prepared from a novel thioacetic acid-based solution and their photovoltaic application.

    Science.gov (United States)

    Xie, Yian; Liu, Yufeng; Wang, Yaoming; Zhu, Xiaolong; Li, Aimin; Zhang, Lei; Qin, Mingsheng; Lü, Xujie; Huang, Fuqiang

    2014-04-28

    Low-cost and high-yield preparation of CuInSe2 films is the bottleneck for promising CuInSe2-based thin film solar cells. Here, we developed a simple, safe and cost-effective method using thioacetic acid to fabricate the absorber films of CuIn(S,Se)2 (CISSe). Dissolution of Cu2O and In(OH)3 in thioacetic acid was attributed to the strong coordination ability of S. The adhesive precursor solution can be prepared without any heating, centrifugation and inert gas protection, superior to the previously reported methods. The precursor CISSe layer was easily deposited in air by spin coating to ensure low cost. Uniform and compact CISSe thin films with well-crystallized and pure-phased CISSe grains were obtained after one step annealing. The as-prepared CISSe thin films were successfully applied to solar cells and a energy conversion efficiency of 6.75% was achieved. This facile preparation provides a low-cost and easy method to fabricate Cu-based thin film solar cells. PMID:24632726

  14. Design of a compact waveguide optical isolator based on multimode interferometers using magneto-optical oxide thin films grown on silicon-on-insulator substrates.

    Science.gov (United States)

    Shui, Keyi; Nie, Lixia; Zhang, Yan; Peng, Bo; Xie, Jianliang; Deng, Longjiang; Bi, Lei

    2016-06-13

    We report the design of a waveguide optical isolator based on multimode interferometer (MMI) structure using silicon on insulator (SOI) and deposited magneto-optical (MO) thin films. The optical isolator is based on a vertical 1 × 2 SOI MMI utilizing the nonreciprocal phase shift (NRPS) difference of different TM modes of the MO garnet thin film/SOI waveguide. By constructing a silicon/MO thin film/silicon structure, we demonstrate that the NRPS of the fundamental and first order TM modes can show opposite signs for certain device dimensions, therefore significantly reduce the device length. For a 310.42 μm long device, 20 dB isolation bandwidth larger than 1.6 nm with total insertion loss of 0.817 dB is achieved at 1550 nm wavelength. The fabrication tolerances and materials losses are also discussed to satisfy the state-of-the-art fabrication technology and material properties. PMID:27410305

  15. Thin film cadmium telluride solar cells

    Science.gov (United States)

    Chu, T. L.; Chu, Shirley S.; Ang, S. T.; Mantravadi, M. K.

    1987-08-01

    Thin-film p-CdTe/CdS/SnO2:F/glass solar cells of the inverted configuration were prepared by the deposition of p-type CdTe films onto CdS/SnO2:F/glass substrates using CVD or close-spaced sublimation (CSS) techniques based on the procedures of Chu et al. (1983) and Nicholl (1963), respectively. The deposition rates of p-CdTe films deposited by CSS were higher than those deposited by the CVD technique (4-5 min were sufficient), and the efficiencies higher than 10 percent were obtained. However, the resistivity of films prepared by CSS was not as readily controlled as that of the CVD films. The simplest technique to reduce the resistivity of the CSS p-CdTe films was to incorporate a dopant, such as As or Sb, into the reaction mixture during the preparation of the source material. The films with resistivities in the range of 500-1000 ohm cm were deposited in this manner.

  16. Multiferroic oxide thin films and heterostructures

    KAUST Repository

    Lu, Chengliang

    2015-05-26

    Multiferroic materials promise a tantalizing perspective of novel applications in next-generation electronic, memory, and energy harvesting technologies, and at the same time they also represent a grand scientific challenge on understanding complex solid state systems with strong correlations between multiple degrees of freedom. In this review, we highlight the opportunities and obstacles in growing multiferroic thin films with chemical and structural integrity and integrating them in functional devices. Besides the magnetoelectric effect, multiferroics exhibit excellent resistant switching and photovoltaic properties, and there are plenty opportunities for them to integrate with other ferromagnetic and superconducting materials. The challenges include, but not limited, defect-related leakage in thin films, weak magnetism, and poor control on interface coupling. Although our focuses are Bi-based perovskites and rare earth manganites, the insights are also applicable to other multiferroic materials. We will also review some examples of multiferroic applications in spintronics, memory, and photovoltaic devices.

  17. Multiferroic oxide thin films and heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Chengliang, E-mail: cllu@mail.hust.edu.cn, E-mail: Tao.Wu@kaust.edu.sa [School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China); Hu, Weijin; Wu, Tom, E-mail: cllu@mail.hust.edu.cn, E-mail: Tao.Wu@kaust.edu.sa [Physical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900 (Saudi Arabia); Tian, Yufeng [School of Physics, Shandong University, Jinan 250100 (China)

    2015-06-15

    Multiferroic materials promise a tantalizing perspective of novel applications in next-generation electronic, memory, and energy harvesting technologies, and at the same time they also represent a grand scientific challenge on understanding complex solid state systems with strong correlations between multiple degrees of freedom. In this review, we highlight the opportunities and obstacles in growing multiferroic thin films with chemical and structural integrity and integrating them in functional devices. Besides the magnetoelectric effect, multiferroics exhibit excellent resistant switching and photovoltaic properties, and there are plenty opportunities for them to integrate with other ferromagnetic and superconducting materials. The challenges include, but not limited, defect-related leakage in thin films, weak magnetism, and poor control on interface coupling. Although our focuses are Bi-based perovskites and rare earth manganites, the insights are also applicable to other multiferroic materials. We will also review some examples of multiferroic applications in spintronics, memory, and photovoltaic devices.

  18. High efficiency thin film CdTe and a-Si based solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Compaan, A. D.; Deng, X.; Bohn, R. G.

    2000-01-04

    This report describes work done by the University of Toledo during the first year of this subcontract. During this time, the CdTe group constructed a second dual magnetron sputter deposition facility; optimized reactive sputtering for ZnTe:N films to achieve 10 ohm-cm resistivity and {approximately}9% efficiency cells with a copper-free ZnTe:N/Ni contact; identified Cu-related photoluminescence features and studied their correlation with cell performance including their dependence on temperature and E-fields; studied band-tail absorption in CdS{sub x}Te{sub 1{minus}x} films at 10 K and 300 K; collaborated with the National CdTe PV Team on (1) studies of high-resistivity tin oxide (HRT) layers from ITN Energy Systems, (2) fabrication of cells on the HRT layers with 0, 300, and 800-nm CdS, and (3) preparation of ZnTe:N-based contacts on First Solar materials for stress testing; and collaborated with Brooklyn College for ellipsometry studies of CdS{sub x}Te{sub 1{minus}x} alloy films, and with the University of Buffalo/Brookhaven NSLS for synchrotron X-ray fluorescence studies of interdiffusion in CdS/CdTe bilayers. The a-Si group established a baseline for fabricating a-Si-based solar cells with single, tandem, and triple-junction structures; fabricated a-Si/a-SiGe/a-SiGe triple-junction solar cells with an initial efficiency of 9.7% during the second quarter, and 10.6% during the fourth quarter (after 1166 hours of light-soaking under 1-sun light intensity at 50 C, the 10.6% solar cells stabilized at about 9%); fabricated wide-bandgap a-Si top cells, the highest Voc achieved for the single-junction top cell was 1.02 V, and top cells with high FF (up to 74%) were fabricated routinely; fabricated high-quality narrow-bandgap a-SiGe solar cells with 8.3% efficiency; found that bandgap-graded buffer layers improve the performance (Voc and FF) of the narrow-bandgap a-SiGe bottom cells; and found that a small amount of oxygen partial pressure ({approximately}2 {times} 10

  19. Free standing diamond-like carbon thin films by PLD for laser based electrons/protons acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Thema, F.T.; Beukes, P.; Ngom, B.D. [UNESCO Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West, 7129, PO Box722, Western Cape Province (South Africa); Manikandan, E., E-mail: mani@tlabs.ac.za [UNESCO Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West, 7129, PO Box722, Western Cape Province (South Africa); Central Research Laboratory, Sree Balaji Medical College & Hospital (SBMCH), Chrompet, Bharath University, Chennai, 600044 (India); Maaza, M., E-mail: maaza@tlabs.ac.za [UNESCO Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West, 7129, PO Box722, Western Cape Province (South Africa)

    2015-11-05

    This study we reports for the first time on the synthesis and optical characteristics of free standing diamond-like carbon (DLC) deposited by pulsed laser deposition (PLD) onto graphene buffer layers for ultrahigh intensity laser based electron/proton acceleration applications. The fingerprint techniques of micro-Raman, UV–VIS–NIR and the IR spectroscopic investigations indicate that the suitability of such free standing DLC thin-films within the laser window and long wave infrared (LWIR) spectral range and hence their appropriateness for the targeted applications. - Highlights: • We report for the first time synthesis of free standing diamond-like carbon. • Pulsed laser deposition onto graphene buffer layers. • Fingerprint techniques of micro-Raman, UV–VIS–NIR and the IR spectroscopic investigations. • Ultrahigh intensity laser based electron/proton acceleration applications. • This material's suitable for the laser window and long wave infrared (LWIR) spectral range.

  20. Gas-sensitive properties of thin film heterojunction structures based on Fe2O3-In2O3 nanocomposites

    OpenAIRE

    Ivanovskaya, M.; Kotsikau, D.; Faglia, G.; Nelli, P.; Irkaev, S.

    2003-01-01

    This paper reports an investigation of the gas-sensitive properties of thin film based on the double-layers Fe2O3/In2O3 and Fe2O3-In2O3/In2O3 towards gases with different chemical nature (C2H5OH, CH4, CO, NH3, NO2, O3). As it was found, the -Fe2O3-In2O3 composite (Fe:In = 9:1) is more sensitive to O3; on the contrary, the -Fe2O3-In2O3 system (9:1), possesses an higher sensitivity to NO2. The optimal temperature for detecting both gases is in the range 70 - 100C. Sensors based on the -Fe2O...

  1. Free standing diamond-like carbon thin films by PLD for laser based electrons/protons acceleration

    International Nuclear Information System (INIS)

    This study we reports for the first time on the synthesis and optical characteristics of free standing diamond-like carbon (DLC) deposited by pulsed laser deposition (PLD) onto graphene buffer layers for ultrahigh intensity laser based electron/proton acceleration applications. The fingerprint techniques of micro-Raman, UV–VIS–NIR and the IR spectroscopic investigations indicate that the suitability of such free standing DLC thin-films within the laser window and long wave infrared (LWIR) spectral range and hence their appropriateness for the targeted applications. - Highlights: • We report for the first time synthesis of free standing diamond-like carbon. • Pulsed laser deposition onto graphene buffer layers. • Fingerprint techniques of micro-Raman, UV–VIS–NIR and the IR spectroscopic investigations. • Ultrahigh intensity laser based electron/proton acceleration applications. • This material's suitable for the laser window and long wave infrared (LWIR) spectral range

  2. ANFIS-based approach to studying subthreshold behavior including the traps effect for nanoscale thin-film DG MOSFETs

    International Nuclear Information System (INIS)

    A fuzzy framework based on an adaptive network fuzzy inference system (ANFIS) is proposed to evaluate the relative degradation of the basic subthreshold parameters due to hot-carrier effects for nanoscale thin-film double-gate (DG) MOSFETs. The effect of the channel length and thickness on the resulting degradation is addressed, and 2-D numerical simulations are used for the elaboration of the training database. Several membership function shapes are developed, and the best one in terms of accuracy is selected. The predicted results agree well with the 2-D numerical simulations and can be efficiently used to investigate the impact of the interface fixed charges and quantum confinement on nanoscale DG MOSFET subthreshold behavior. Therefore, the proposed ANFIS-based approach offers a simple and accurate technique to study nanoscale devices, including the hot-carrier and quantum effects. (semiconductor devices)

  3. ANFIS-based approach to studying subthreshold behavior including the traps effect for nanoscale thin-film DG MOSFETs

    Institute of Scientific and Technical Information of China (English)

    T.Bentrcia; F.Djeffal; E.Chebaaki

    2013-01-01

    A fuzzy framework based on an adaptive network fuzzy inference system (ANFIS) is proposed to evaluate the relative degradation of the basic subthreshold parameters due to hot-carrier effects for nanoscale thin-film double-gate (DG) MOSFETs.The effect of the channel length and thickness on the resulting degradation is addressed,and 2-D numerical simulations are used for the elaboration of the training database.Several membership function shapes are developed,and the best one in terms of accuracy is selected.The predicted results agree well with the 2-D numerical simulations and can be efficiently used to investigate the impact of the interface fixed charges and quantum confinement on nanoscale DG MOSFET subthreshold behavior.Therefore,the proposed ANFIS-based approach offers a simple and accurate technique to study nanoscale devices,including the hot-carrier and quantum effects.

  4. Improved electrochromic performances of NiO based thin films by lithium addition: From single layers to devices

    International Nuclear Information System (INIS)

    Aiming at enhancing the electrochromic properties of anodically colored NiO thin films, lithium doped NiO thin films were grown on FTO/glass substrates, by the pulsed laser deposition (PLD) method. Optimized conditions, namely a room temperature substrate under 10 Pa oxygen pressure were used. Comparison with undoped NiO thin films indicates that lithium doping deteriorates NiO cubic phase (1 1 1) preferred orientation and also induces lattice disorder. The investigation of the electrochromic properties of Li–Ni–O thin films in aqueous liquid electrolyte, 1 M KOH, on the one hand and in hydrophobic lithium conductive ionic liquid, 0.3 M LiTFSI in BMITFSI, on the other hand, demonstrates an improvement in the electrochromic performances with lithium doping. Finally, electrochromic devices built on the association of WO3 and Li–Ni–O thin films and using the above quoted ionic liquid blended with PMMA as electrolyte are reported. Good electrochromic performances and neutral color are shown.

  5. Ellipsometric Studies on Silver Telluride Thin Films

    Directory of Open Access Journals (Sweden)

    M. Pandiaraman

    2011-01-01

    Full Text Available Silver telluride thin films of thickness between 45 nm and 145 nm were thermally evaporated on well cleaned glass substrates at high vacuum better than 10 – 5 mbar. Silver telluride thin films are polycrystalline with monoclinic structure was confirmed by X-ray diffractogram studies. AFM and SEM images of these films are also recorded. The phase ratio and amplitude ratio of these films were recorded in the wavelength range between 300 nm and 700 nm using spectroscopic ellipsometry and analysed to determine its optical band gap, refractive index, extinction coefficient, and dielectric functions. High absorption coefficient determined from the analysis of recorded spectra indicates the presence of direct band transition. The optical band gap of silver telluride thin films is thickness dependent and proportional to square of reciprocal of thickness. The dependence of optical band gap of silver telluride thin films on film thickness has been explained through quantum size effect.

  6. Laser induced vibration of a thin soap film.

    OpenAIRE

    Emile, Olivier; Emile, Janine

    2014-01-01

    We report on the vibration of a thin soap film based on the optical radiation pressure force. The modulated low power laser induces a counter gravity flow in a vertical free standing draining film. The thickness of the soap film is then higher in the upper region than in the lower region of the film. Moreover, the lifetime of the film is dramatically increased by a factor of 2. Since the laser beam only acts mechanically on the film interfaces, such a film can be implemented in an optofluidic...

  7. Corrosion in low dielectric constant Si-O based thin films: Buffer concentration effects

    Directory of Open Access Journals (Sweden)

    F. W. Zeng

    2014-05-01

    Full Text Available Organosilicate glass (OSG is often used as an interlayer dielectric (ILD in high performance integrated circuits. OSG is a brittle material and prone to stress-corrosion cracking reminiscent of that observed in bulk glasses. Of particular concern are chemical-mechanical planarization techniques and wet cleans involving solvents commonly encountered in microelectronics fabrication where the organosilicate film is exposed to aqueous environments. Previous work has focused on the effect of pH, surfactant, and peroxide concentration on the subcritical crack growth of these films. However, little or no attention has focused on the effect of the conjugate acid/base concentration in a buffer. Accordingly, this work examines the “strength” of the buffer solution in both acidic and basic environments. The concentration of the buffer components is varied keeping the ratio of acid/base and therefore pH constant. In addition, the pH was varied by altering the acid/base ratio to ascertain any additional effect of pH. Corrosion tests were conducted with double-cantilever beam fracture mechanics specimens and fracture paths were verified with ATR-FTIR. Shifts in the threshold fracture energy, the lowest energy required for bond rupture in the given environment, GTH, were found to shift to lower values as the concentration of the base in the buffer increased. This effect was found to be much larger than the effect of the hydroxide ion concentration in unbuffered solutions. The results are rationalized in terms of the salient chemical bond breaking process occurring at the crack tip and modeled in terms of the chemical potential of the reactive species.

  8. Corrosion in low dielectric constant Si-O based thin films: Buffer concentration effects

    International Nuclear Information System (INIS)

    Organosilicate glass (OSG) is often used as an interlayer dielectric (ILD) in high performance integrated circuits. OSG is a brittle material and prone to stress-corrosion cracking reminiscent of that observed in bulk glasses. Of particular concern are chemical-mechanical planarization techniques and wet cleans involving solvents commonly encountered in microelectronics fabrication where the organosilicate film is exposed to aqueous environments. Previous work has focused on the effect of pH, surfactant, and peroxide concentration on the subcritical crack growth of these films. However, little or no attention has focused on the effect of the conjugate acid/base concentration in a buffer. Accordingly, this work examines the “strength” of the buffer solution in both acidic and basic environments. The concentration of the buffer components is varied keeping the ratio of acid/base and therefore pH constant. In addition, the pH was varied by altering the acid/base ratio to ascertain any additional effect of pH. Corrosion tests were conducted with double-cantilever beam fracture mechanics specimens and fracture paths were verified with ATR-FTIR. Shifts in the threshold fracture energy, the lowest energy required for bond rupture in the given environment, GTH, were found to shift to lower values as the concentration of the base in the buffer increased. This effect was found to be much larger than the effect of the hydroxide ion concentration in unbuffered solutions. The results are rationalized in terms of the salient chemical bond breaking process occurring at the crack tip and modeled in terms of the chemical potential of the reactive species

  9. Corrosion in low dielectric constant Si-O based thin films: Buffer concentration effects

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, F. W.; Lane, M. W., E-mail: mlane@ehc.edu [Department of Chemistry, Emory and Henry College, Emory, Virginia 24340 (United States); Gates, S. M. [IBM TJ Watson Research Center, Yorktown Heights, New York 10598 (United States)

    2014-05-15

    Organosilicate glass (OSG) is often used as an interlayer dielectric (ILD) in high performance integrated circuits. OSG is a brittle material and prone to stress-corrosion cracking reminiscent of that observed in bulk glasses. Of particular concern are chemical-mechanical planarization techniques and wet cleans involving solvents commonly encountered in microelectronics fabrication where the organosilicate film is exposed to aqueous environments. Previous work has focused on the effect of pH, surfactant, and peroxide concentration on the subcritical crack growth of these films. However, little or no attention has focused on the effect of the conjugate acid/base concentration in a buffer. Accordingly, this work examines the “strength” of the buffer solution in both acidic and basic environments. The concentration of the buffer components is varied keeping the ratio of acid/base and therefore pH constant. In addition, the pH was varied by altering the acid/base ratio to ascertain any additional effect of pH. Corrosion tests were conducted with double-cantilever beam fracture mechanics specimens and fracture paths were verified with ATR-FTIR. Shifts in the threshold fracture energy, the lowest energy required for bond rupture in the given environment, G{sub TH}, were found to shift to lower values as the concentration of the base in the buffer increased. This effect was found to be much larger than the effect of the hydroxide ion concentration in unbuffered solutions. The results are rationalized in terms of the salient chemical bond breaking process occurring at the crack tip and modeled in terms of the chemical potential of the reactive species.

  10. The state of the art of thin-film photovoltaics

    International Nuclear Information System (INIS)

    Thin-film photovoltaic technologies, based on materials such as amorphous or polycrystalline silicon, copper indium diselenide, cadmium telluride, and gallium arsenide, offer the potential for significantly reducing the cost of electricity generated by photovoltaics. The significant progress in the technologies, from the laboratory to the marketplace, is reviewed. The common concerns and questions raised about thin films are addressed. Based on the progress to date and the potential of these technologies, along with continuing investments by the private sector to commercialize the technologies, one can conclude that thin-film PV will provide a competitive alternative for large-scale power generation in the future

  11. Light management in thin-film silicon solar cells

    OpenAIRE

    Isabella, O.

    2013-01-01

    Solar energy can fulfil mankind’s energy needs and secure a more balanced distribution of primary sources of energy. Wafer-based and thin-film silicon solar cells dominate todays’ photovoltaic market because silicon is a non-toxic and abundant material and high conversion efficiencies are achieved with silicon-based solar cells. To stay competitive with bulk crystalline silicon and other thin-film solar cell technologies, thin-film silicon solar cells have to achieve a conversion efficiency l...

  12. Super-resolution readout property of bismuth-doped antimony-based thin film as a functional mask for read-only memory

    Science.gov (United States)

    Lu, Xinmiao; Wu, Yiqun; Wang, Yang; Wei, Jingsong

    2012-09-01

    Bismuth-doped antimony-based (Sb100- x Bi x , x=2.46) thin films were presented as a functional mask for super-resolution readout of read-only memory (ROM). The pit size of the ROM was 390 nm, and super-resolution readout was realized on a dynamic tester with laser wavelength of 780 nm and the numerical aperture of the focusing objective lens of 0.45. The carrier-to-noise ratio (CNR) of 22 dB, readout threshold power of 0.8 mW and super-resolution readout cycles of 2×104 was achieved. The influence of film thickness and readout power on CNR was investigated. The reflectivity and transmittance of the film with different temperature at wavelength of 780 nm were detected, and the super-resolution mechanism of the bismuth-doped antimony-based thin films as the functional mask layer was discussed.

  13. Durability of VO 2 -based thin films at elevated temperature : Towards thermochromic fenestration

    OpenAIRE

    Ji, Yu-Xia; Niklasson, Gunnar A.; Granqvist, Claes-Göran

    2014-01-01

    An explorative study was performed on sputter-deposited thermochromic VO 2 films with top coatings of Al oxide and Al nitride. The films were exposed to dry air at a high temperature. Bare 80-nm-thick VO 2 films rapidly converted to non-thermochromic V 2 O 5 under the chosen conditions. Al oxide top coatings protected the underlying VO 2 films and, expectedly, increased film thickness yielded improved protection. Specifically, it was found that a 30-nm-thick sputter-deposited Al oxide top coa...

  14. Development of neutron diffuse scattering analysis code by thin film and multilayer film

    International Nuclear Information System (INIS)

    To research surface structure of thin film and multilayer film by neutron, a neutron diffuse scattering analysis code using DWBA (Distorted-Wave Bron Approximation) principle was developed. Subjects using this code contain the surface and interface properties of solid/solid, solid/liquid, liquid/liquid and gas/liquid, and metal, magnetism and polymer thin film and biomembran. The roughness of surface and interface of substance shows fractal self-similarity and its analytical model is based on DWBA theory by Sinha. The surface and interface properties by diffuse scattering are investigated on the basis of the theoretical model. The calculation values are proved to be agreed with the experimental values. On neutron diffuse scattering by thin film, roughness of surface of thin film, correlation function, neutron propagation by thin film, diffuse scattering by DWBA theory, measurement model, SDIFFF (neutron diffuse scattering analysis program by thin film) and simulation results are explained. On neutron diffuse scattering by multilayer film, roughness of multilayer film, principle of diffuse scattering, measurement method and simulation examples by MDIFF (neutron diffuse scattering analysis program by multilayer film) are explained. (S.Y.)To research surface structure of thin film and multilayer film by neutron, a neutron diffuse scattering analysis code using DWBA (Distorted-Wave Bron Approximation) principle was developed. Subjects using this code contain the surface and interface properties of solid/solid, solid/liquid, liquid/liquid and gas/liquid, and metal, magnetism and polymer thin film and biomembran. The roughness of surface and interface of substance shows fractal self-similarity and its analytical model is based on DWBA theory by Sinha. The surface and interface properties by diffuse scattering are investigated on the basis of the theoretical model. The calculation values are proved to be agreed with the experimental values. On neutron diffuse scattering

  15. Highly spectrum-selective ultraviolet photodetector based on p-NiO/n-IGZO thin film heterojunction structure.

    Science.gov (United States)

    Li, H K; Chen, T P; Hu, S G; Li, X D; Liu, Y; Lee, P S; Wang, X P; Li, H Y; Lo, G Q

    2015-10-19

    Ultraviolet photodetector with p-n heterojunction is fabricated by magnetron sputtering deposition of n-type indium gallium zinc oxide (n-IGZO) and p-type nickel oxide (p-NiO) thin films on ITO glass. The performance of the photodetector is largely affected by the conductivity of the p-NiO thin film, which can be controlled by varying the oxygen partial pressure during the deposition of the p-NiO thin film. A highly spectrum-selective ultraviolet photodetector has been achieved with the p-NiO layer with a high conductivity. The results can be explained in terms of the "optically-filtering" function of the NiO layer.

  16. Impact of different polyimide-based substrates on the soft magnetic properties of NiFe thin films

    Science.gov (United States)

    Rittinger, Johannes; Taptimthong, Piriya; Jogschies, Lisa; Wurz, Marc C.; Rissing, Lutz

    2015-05-01

    We investigated the impact of polymer substrates on the magnetic properties of soft magnetic thin films. Experiments were carried out to evaluate the performance of AMR (anisotropic magnetoresistive) sensors deposited on polymeric substrates and to give indications for the design of future sensors on flexible substrates. Sputtered permalloy (NiFe 81/19) was used as a soft magnetic thin film layer. As substrate materials, liquid polyimide precursors and DuPont Kapton® HN foil were examined. Surface roughness was determined for each substrate material. The dynamic of soft magnetic behavior of the permalloy thin films was observed in a homogenous alternating magnetic field. Resulting R-Hcurves were evaluated in regard to the magnitude of the magnetoresistive effect (ΔR / R0-ratio), as well as the resulting magnetic anisotropy of the tested samples. B-H-curves were obtained by means of a vibrating sample magnetometer (VSM).

  17. Highly spectrum-selective ultraviolet photodetector based on p-NiO/n-IGZO thin film heterojunction structure.

    Science.gov (United States)

    Li, H K; Chen, T P; Hu, S G; Li, X D; Liu, Y; Lee, P S; Wang, X P; Li, H Y; Lo, G Q

    2015-10-19

    Ultraviolet photodetector with p-n heterojunction is fabricated by magnetron sputtering deposition of n-type indium gallium zinc oxide (n-IGZO) and p-type nickel oxide (p-NiO) thin films on ITO glass. The performance of the photodetector is largely affected by the conductivity of the p-NiO thin film, which can be controlled by varying the oxygen partial pressure during the deposition of the p-NiO thin film. A highly spectrum-selective ultraviolet photodetector has been achieved with the p-NiO layer with a high conductivity. The results can be explained in terms of the "optically-filtering" function of the NiO layer. PMID:26480430

  18. Growth and transport properties of thin Co-based Heusler films; Wachstum und Transporteigenschaften duenner Co-basierter Heusler-Filme

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, Horst

    2010-07-01

    During this work, thin films of Co-based Heusler compounds were deposited under optimized conditions, and their structural, magnetic, and transport properties were investigated. The growth of the thin film samples was accomplished by two different methods. At first Co{sub 2}Cr{sub 0.6}Fe{sub 0.4}Al and Co{sub 2}FeSi were deposited by sputter deposition from stoichiometric targets. This is considered the standard technique for the preparation of thin Heusler films. Also for the compounds investigated here it resulted in samples with a high degree of L2{sub 1} ordering. An excess of Fe atoms on Si sites was discovered by a detailed X-ray analysis in conjunction with NMR spectroscopy. The choice of different substrates allowed the adjustment of the growth direction. On the other hand, bulk magnetometry revealed that these sputter deposited films exhibit only a reduced magnetic moment, which is an indication of a reduced spin asymmetry at the Fermi level. One source of this problem seems to be a high residual gas pressure, which leads to an increased sample contamination. To improve this situation, a pulsed laser deposition system was constructed and put into operation. The resulting film growth under ultra-high vacuum conditions led to a further improvement of the short-range crystallographic ordering and a clear enhancement of the magnetic properties. The additional use of a metallic buffer layer resulted in samples with a smooth surface. This opens the door for a number of further analytical experiments, such as tunneling spectroscopy or Brillouin light scattering. After this successful demonstration of this growth technique, an additional method for the flexible variation of the film stoichiometry was implemented. In this work, this method was successfully applied in the deposition of Co{sub 2}Mn{sub 1-x}Fe{sub x}Si films. All samples in this series show a high degree of atomic ordering. Their magnetization values are compatible with the Slater-Pauling rule for

  19. Erbium-Doped Amorphous Carbon-Based Thin Films: A Photonic Material Prepared by Low-Temperature RF-PEMOCVD

    Directory of Open Access Journals (Sweden)

    Hui-Lin Hsu

    2014-02-01

    Full Text Available The integration of photonic materials into CMOS processing involves the use of new materials. A simple one-step metal-organic radio frequency plasma enhanced chemical vapor deposition system (RF-PEMOCVD was deployed to grow erbium-doped amorphous carbon thin films (a-C:(Er on Si substrates at low temperatures (<200 °C. A partially fluorinated metal-organic compound, tris(6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5- octanedionate Erbium(+III or abbreviated Er(fod3, was incorporated in situ into a-C based host. Six-fold enhancement of Er room-temperature photoluminescence at 1.54 µm was demonstrated by deuteration of the a-C host. Furthermore, the effect of RF power and substrate temperature on the photoluminescence of a-C:D(Er films was investigated and analyzed in terms of the film structure. Photoluminescence signal increases with increasing RF power, which is the result of an increase in [O]/[Er] ratio and the respective erbium-oxygen coordination number. Moreover, photoluminescence intensity decreases with increasing substrate temperature, which is attributed to an increased desorption rate or a lower sticking coefficient of the fluorinated fragments during film growth and hence [Er] decreases. In addition, it is observed that Er concentration quenching begins at ~2.2 at% and continues to increase until 5.5 at% in the studied a-C:D(Er matrix. This technique provides the capability of doping Er in a vertically uniform profile.

  20. Growth of II-VI thin-films from single-source precursors based on sterically encumbered sitel ligands

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, J.; Seligson, A.L.; Walker, J.M.; Bourret, E.D.; Bonasia, P.J.

    1992-04-01

    We have developed a new route to MOCVD of II-VI compounds based on the use of novel single-source precursors in which the II-VI elements are combined at the molecular level in a single covalent compound. We have prepared and fully characterized a number of new derivatives of zinc, cadmium and mercury incorporating large, sterically demanding tellurolate ligands of general formula: M(sitel){sub 2} where sitel = -TeSi(SiMe{sub 3}){sub 3}. The crystalline compounds are relatively volatile and are easily manipulated under nitrogen. Several of these compounds have been tested for their suitability as precursors in the MOCVD process. Clean pyrolysis reactions and deposition of thin films were achieved. The stoichiometry of the pyrolysis reaction has been determined by analysis of the reaction by-products.

  1. Bidirectional current triggering in planar devices based on serially connected VO2 thin films using 965 nm laser diode.

    Science.gov (United States)

    Kim, Jihoon; Park, Kyongsoo; Kim, Bong-Jun; Lee, Yong Wook

    2016-08-01

    By incorporating a 965 nm laser diode, the bidirectional current triggering of up to 30 mA was demonstrated in a two-terminal planar device based on serially connected vanadium dioxide (VO2) thin films grown by pulsed laser deposition. The bidirectional current triggering was realized by using the focused beams of laser pulses through the photo-thermally induced phase transition of VO2. The transient responses of laser-triggered currents were also investigated when laser pulses excited the device at a variety of pulse widths and repetition rates of up to 4.0 Hz. A switching contrast between off- and on-state currents was obtained as ~8333, and rising and falling times were measured as ~39 and ~29 ms, respectively, for 50 ms laser pulses. PMID:27505740

  2. All-Printed Thin-Film Transistor Based on Purified Single-Walled Carbon Nanotubes with Linear Response

    Directory of Open Access Journals (Sweden)

    Guiru Gu

    2011-01-01

    Full Text Available We report an all-printed thin-film transistor (TFT on a polyimide substrate with linear transconductance response. The TFT is based on our purified single-walled carbon nanotube (SWCNT solution that is primarily consists of semiconducting carbon nanotubes (CNTs with low metal impurities. The all-printed TFT exhibits a high ON/OFF ratio of around 103 and bias-independent transconductance over a certain gate bias range. Such bias-independent transconductance property is different from that of conventional metal-oxide-semiconductor field-effect transistors (MOSFETs due to the special band structure and the one-dimensional (1D quantum confined density of state (DOS of CNTs. The bias-independent transconductance promises modulation linearity for analog electronics.

  3. Preparation of thin film nanofibrous composite NF membrane based on EDC/NHS modified PAN-AA nanofibrous substrate

    Science.gov (United States)

    Yang, Y.; Wang, X.; Hsiao, B. S.

    2016-07-01

    A novel kind of thin-film nanofibrous composite (TFNC) nanofiltration (NF) membranes consisting of a polyamide (PA) barrier layer were successfully fabricated by interfacial polymerization (IFP) based on electrospun double-layer nanofibrous substrates, which have an ultrathin poly (acrylonitrile-co-acrylic acid) (PAN-AA) nanofibrous layer as top layer and a thicker polyacrylonitrile (PAN) nanofiber layer as bottom porous support layer. Immersing PAN/PAN-AA nanofibrous substrates into 1-ethyl-(3-3-dimethylaminopropyl) carbodiimide hydrochloride/N-hydroxysuccinimide (EDC/NHS) aqueous solution and piperazine (PIP) aqueous solution (0.20 wt%) sequentially for a period of time, the carboxyl groups on PAN-AA nanofibers were activated by carbodiimide and then reacted with the amide groups. The as prepared composite membrane has an integrated structure with high rejection rate (98.0%); high permeate flux (40.4 L/m2h) for MgSO4 aqueous solution (2 g/L).

  4. Nanostructured thin films and coatings functional properties

    CERN Document Server

    Zhang, Sam

    2010-01-01

    The second volume in ""The Handbook of Nanostructured Thin Films and Coatings"" set, this book focuses on functional properties, including optical, electronic, and electrical properties, as well as related devices and applications. It explores the large-scale fabrication of functional thin films with nanoarchitecture via chemical routes, the fabrication and characterization of SiC nanostructured/nanocomposite films, and low-dimensional nanocomposite fabrication and applications. The book also presents the properties of sol-gel-derived nanostructured thin films as well as silicon nanocrystals e

  5. Codoping of zinc and tungsten for practical high-performance amorphous indium-based oxide thin film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Kizu, Takio, E-mail: KIZU.Takio@nims.go.jp, E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Mitoma, Nobuhiko; Tsukagoshi, Kazuhito, E-mail: KIZU.Takio@nims.go.jp, E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp [International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Miyanaga, Miki; Awata, Hideaki [Advanced Materials R& D Laboratories, Sumitomo Electric Industries, Ltd., 1-1-1 Koyakita, Itami, Hyogo 664-0016 (Japan); Nabatame, Toshihide [MANA Foundry and MANA Advanced Device Materials Group, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

    2015-09-28

    Using practical high-density sputtering targets, we investigated the effect of Zn and W codoping on the thermal stability of the amorphous film and the electrical characteristics in thin film transistors. zinc oxide is a potentially conductive component while W oxide is an oxygen vacancy suppressor in oxide films. The oxygen vacancy from In-O and Zn-O was suppressed by the W additive because of the high oxygen bond dissociation energy. With controlled codoping of W and Zn, we demonstrated a high mobility with a maximum mobility of 40 cm{sup 2}/V s with good stability under a negative bias stress in InWZnO thin film transistors.

  6. Codoping of zinc and tungsten for practical high-performance amorphous indium-based oxide thin film transistors

    International Nuclear Information System (INIS)

    Using practical high-density sputtering targets, we investigated the effect of Zn and W codoping on the thermal stability of the amorphous film and the electrical characteristics in thin film transistors. zinc oxide is a potentially conductive component while W oxide is an oxygen vacancy suppressor in oxide films. The oxygen vacancy from In-O and Zn-O was suppressed by the W additive because of the high oxygen bond dissociation energy. With controlled codoping of W and Zn, we demonstrated a high mobility with a maximum mobility of 40 cm2/V s with good stability under a negative bias stress in InWZnO thin film transistors

  7. Combining mixed titania morphologies into a complex assembly thin film by iterative block-copolymer-based sol-gel templating

    Science.gov (United States)

    Niedermeier, M. A.; Magerl, D.; Zhong, Q.; Nathan, A.; Körstgens, V.; Perlich, J.; Roth, S. V.; Müller-Buschbaum, P.

    2012-04-01

    Sol-gel templating combined with iterative spin-coating steps are used to custom-tailor hierarchically structured titania thin films. Using poly(styrene-block-ethylene oxide) P(S-b-PEO) as the structure directing agent, a foam-like structure is combined with nanogranules. Both structural elements are merged into a complex assembly in thin film geometry. The resulting morphology is pictured by SEM and probed with GISAXS. The installed mesoporous titania sandwich structure exhibits holes with a size of 45 nm which makes it promising for applications in photovoltaics or photocatalysis. An optical characterization completes the structural investigation.

  8. Fully transparent thin film transistors based on zinc oxide channel layer and molybdenum doped indium oxide electrodes

    Science.gov (United States)

    MÄ dzik, Mateusz; Elamurugu, Elangovan; Viegas, Jaime

    2016-03-01

    In this work we report the fabrication of thin film transistors (TFT) with zinc oxide channel and molybdenum doped indium oxide (IMO) electrodes, achieved by room temperature sputtering. A set of devices was fabricated, with varying channel width and length from 5μm to 300μm. Output and transfer characteristics were then extracted to study the performance of thin film transistors, namely threshold voltage and saturation current, enabling to determine optimal fabrication process parameters. Optical transmission in the UV-VIS-IR are also reported.

  9. Broadband back grating design for thin film solar cells

    KAUST Repository

    Janjua, Bilal

    2013-01-01

    In this paper, design based on tapered circular grating structure was studied, to provide broadband enhancement in thin film amorphous silicon solar cells. In comparison to planar structure an absorption enhancement of ~ 7% was realized.

  10. Piezoelectric thin films: an integrated review of transducers and energy harvesting

    Science.gov (United States)

    Khan, Asif; Abas, Zafar; Kim, Heung Soo; Oh, Il-Kwon

    2016-05-01

    Piezoelectric thin films offer a number of advantages in various applications, such as high energy density harvesters, a wide dynamic range, and high sensitivity sensors, as well as large displacement and low power consumption actuators. This review covers the available material forms and applications of piezoelectric thin films: lead zirconate titanate (PZT)-based thin films, lead-free piezoelectric thin films, piezopolymer films, cellulose-based electroactive paper (EAPap), and many other thin films used for electromechanical transduction. The electromechanical properties and performances of piezoelectric films are compared and their suitability for particular applications are reported. The key ideas of piezoelectric thin films are reviewed and discussed for sensory and actuation systems, energy harvesting, and medical and acoustic transducers. In the last section, an insight into the future outlook and possibilities for thin film-based devices and their integration into real-world applications is presented.

  11. Dielectric thin-films by ion-beam sputtering deposition for III-V based infrared optoelectronic imaging

    Science.gov (United States)

    Nguyen, Jean

    The growing technological industry is demanding the development of powerful and smaller devices. Dielectric thin-films can play an important role to help push towards achieving these goals. However, their advantage of high-quality material and low material costs compared to bulk can only be achieved with consideration of the technique, conditions, and parameters. The sensitivity makes every step in the process extremely important, beginning from substrate preparation to the first initial layers of growth and ending with the testing/modeling of the devices. Further, not all applications want bulk-like properties, so the ability to adjust and fine tune the material characteristics opens up a wide range of opportunities with the advancements and can drive the power of the devices to an ultimate level. This work provides the motivation, theoretical basis, and experimental results for performance enhancement of optoelectronic devices through the use of high-quality dielectric thin-films by ion-beam sputtering deposition (IBSD). The advantages and disadvantages to this technique are demonstrated and compared to others. The optimization processes, relationships, and motivation of using seven different thin-film materials have been detailed and provided. Using IBSD, the performance improvements were demonstrated on infrared lasers and detectors. For lasers, a 170% increase in maximum output power was achieved using near-0% percent anti-reflection coatings (AR) and near-100% high-reflection (HR) coatings. Following, wide tunability was achieved by using the structures in an external cavity laser system, showing nearly a three-fold improvement in tuning range. Also, structurally robust lasers were achieved with a custom-tailored HR structure designed for damage resistance to high output power density operation, showing over 14W of peak output power for MOCVD lasers. For infrared photodetectors, over a 4 orders of magnitude decrease in current density and zero-bias resistance

  12. Microwave absorber based on silver nanoparticle-embedded polymer thin film.

    Science.gov (United States)

    Ramesh, G V; Sudheendran, K; Raju, K C James; Sreedhar, B; Radhakrishnan, T P

    2009-01-01

    Silver nanoparticle-embedded poly(vinyl alcohol) films are fabricated through a simple in situ process. The nanocomposite films are a few hundred nanometers thick with silver concentrations below 10% and the nanoparticles 5-10 nm in diameter. These films are shown to exhibit appreciable microwave absorption in the 8-12 GHz range; the return and insertion losses are found to be sensitive to the nanoparticle content. PMID:19441305

  13. A lossy mode resonance-based fiber optic hydrogen gas sensor for room temperature using coatings of ITO thin film and nanoparticles

    International Nuclear Information System (INIS)

    In this article, the idea of employing lossy mode resonances (LMR) concertedly for gas sensing along with the reversible interaction of metal oxides with gases has been investigated. Fabrication and characterization of a LMR-based fiber optic probe with successive coatings of indium-tin oxide (ITO) film and nanoparticles over the unclad core of the fiber have been carried out for the detection of hydrogen gas (H2). The results have been compared with the probes having individual coatings of ITO thin film and nanoparticles. For calibrating and comparing, the wavelength interrogative spectra have been recorded for varying concentrations of H2 gas exploiting the sensor probes. A red shift of the spectrum has been observed with the increase in the concentration of the gas. The results uphold the fact that the LMR-based sensor with both thin film and nanoparticles layer has better sensitivity to H2 gas than the probes with the layer of either nanoparticles or thin film. A collective study on the three probes for different gases has predicted a maximum level of sensitivity for the probe with layers of thin film and nanoparticles along with the high selectivity and repeatability of the results for H2 gas. In addition to high sensitivity and selectivity, the proposed sensor can be used for online monitoring and remote sensing of the gas because of the fabrication of the probe on the optical fiber. (paper)

  14. Optical Sensors Based on Single on Arm Thin Film Waveguide Interferometer

    Science.gov (United States)

    Sarkisov, S. S.; Diggs, D.; Curley, M.; Adamovsky, Grigory (Technical Monitor)

    2000-01-01

    Single-arm dual-mode optical waveguide interferometer utilizes interference between two modes of different order. Sensing effect results from the change in propagation conditions of the modes caused by the environment. The waveguide is made as an open asymmetric structure containing a dye-doped polymer film onto a quartz substrate. It is more sensitive to the change of environment than its conventional polarimetric analog using orthogonal modes (TE and TM) of the same order. The sensor still preserves the option of operating in polarimetric regime using a variety of mode combinations such as TE(sub 0)/TM(sub 0) (conventional) TE(sub 0)/TM(sub 1), TE(sub 1)/TM(sub 0), or TE(sub 1)/TM(sub 1) but can also work in nonpolarimetric regime using combinations TE(sub 0)/TE(sub 1) or TM(sub 0)/TM(sub 1). Utilization of different mode combinations simultaneously makes the device more versatile. Application of the sensor to gas sensing is based on doping polymer film with an organic indicator dye targeting a particular gaseous reagent. Change of the optical absorption spectrum of the dye caused by the gaseous pollutant results in change of the reactive index of the dye-doped polymer film that can be detected by the sensor. As indicator dyes we utilize Bromocresol Purple doped into polymer poly(methyl) methacrylate that is sensitive to small concentrations of ammonia. The indicator dye demonstrated an irreversible increase in optical absorption near the peak at 350 nm being exposed to 5% ammonia in pure nitrogen at 600 Torr. The dye also showed reversible growth of the absorption peak near 600 nm after exposure to a vapor of standard medical ammonia spirit (65% alcohol). We have built a breadboard prototype of the sensor with He-Ne laser as a light source and with a single mode fiber input and a multimode fiber output. The prototype showed a sensitivity to temperature change of the order of 2 C per 2pi phase shift. The sensitivity of the sensor to the presence of dTy ammonia is

  15. Characteristics of silicon-based BaxSr1-xTiO3 thin films prepared by a sol-gel method

    International Nuclear Information System (INIS)

    Silicon-based BaxSr1-xTiO3 (BST) thin films have been prepared by a sol-gel method with rapid thermal annealing (RTA) processes. Phase structure of the films has been investigated by x-ray diffraction. Atomic force microscopy studies reveal a dense and smooth surface of the sol-gel prepared films. Microstructure and electrical properties of the BST films can be affected by the substrate and the annealing process. RTA method is found to be very efficient to improve the electrical properties of the films. Dielectric constant and dielectric loss of the BST films at 100 kHz are 230 and 0.02, respectively. Leakage current density of the BST capacitors is 1.6x10-7A cm-2 at 3 V. (author)

  16. Epitaxial ferromagnetic thin films and heterostructures of Mn-based metallic and semiconducting compounds on GaAs

    Science.gov (United States)

    Tanaka, Masaaki

    1998-07-01

    We present two approaches to integrate magnetic materials with III-V semiconductors. One is epitaxial ferromagnetic metallic films and heterostructures on GaAs (0 0 1) substrates. Although crystal structure, lattice constant, chemical bonding and other properties are dissimilar, ferromagnetic hexagonal MnAs thin films and MnAs/NiAs ferromagnet/nonmagnet heterostructures (HSs) are grown on GaAs by molecular beam epitaxy (MBE). Multi-stepped magnetic hysteresis are controllably realized in MnAs/NiAs HSs, making this material promising for the application to multi-level nonvolatile recording on semiconductors. The other approach is to prepare a new class of GaAs based magnetic semiconductor, GaMnAs, by low-temperature molecular beam epitaxy (LT-MBE) on GaAs (0 0 1). New III-V based superlattices consisting of ferromagnetic semiconductor GaMnAs and nonmagnetic semiconductor AlAs are also successfully grown. Structural and magnetic properties of these new heterostructures are presented.

  17. Superconducting properties of iron chalcogenide thin films

    Directory of Open Access Journals (Sweden)

    Paolo Mele

    2012-01-01

    Full Text Available Iron chalcogenides, binary FeSe, FeTe and ternary FeTexSe1−x, FeTexS1−x and FeTe:Ox, are the simplest compounds amongst the recently discovered iron-based superconductors. Thin films of iron chalcogenides present many attractive features that are covered in this review, such as: (i easy fabrication and epitaxial growth on common single-crystal substrates; (ii strong enhancement of superconducting transition temperature with respect to the bulk parent compounds (in FeTe0.5Se0.5, zero-resistance transition temperature Tc0bulk = 13.5 K, but Tc0film = 19 K on LaAlO3 substrate; (iii high critical current density (Jc ~ 0.5 ×106 A cm2 at 4.2 K and 0 T for FeTe0.5Se0.5 film deposited on CaF2, and similar values on flexible metallic substrates (Hastelloy tapes buffered by ion-beam assisted deposition with a weak dependence on magnetic field; (iv high upper critical field (~50 T for FeTe0.5Se0.5, Bc2(0, with a low anisotropy, γ ~ 2. These highlights explain why thin films of iron chalcogenides have been widely studied in recent years and are considered as promising materials for applications requiring high magnetic fields (20–50 T and low temperatures (2–10 K.

  18. Thin film cadmium telluride photovoltaic cells

    Energy Technology Data Exchange (ETDEWEB)

    Compaan, A.; Bohn, R. (Toledo Univ., OH (United States))

    1992-04-01

    This report describes research to develop to vacuum-based growth techniques for CdTe thin-film solar cells: (1) laser-driven physical vapor deposition (LDPVD) and (2) radio-frequency (rf) sputtering. The LDPVD process was successfully used to deposit thin films of CdS, CdTe, and CdCl{sub 2}, as well as related alloys and doped semiconductor materials. The laser-driven deposition process readily permits the use of several target materials in the same vacuum chamber and, thus, complete solar cell structures were fabricated on SnO{sub 2}-coated glass using LDPVD. The rf sputtering process for film growth became operational, and progress was made in implementing it. Time was also devoted to enhancing or implementing a variety of film characterization systems and device testing facilities. A new system for transient spectroscopy on the ablation plume provided important new information on the physical mechanisms of LDPVD. The measurements show that, e.g., Cd is predominantly in the neutral atomic state in the plume but with a fraction that is highly excited internally ({ge} 6 eV), and that the typical neutral Cd translational kinetic energies perpendicular to the target are 20 eV and greater. 19 refs.

  19. ENERGY EFFICIENCY OF A PHOTOVOLTAIC CELL BASED THIN FILMS CZTS BY SCAPS

    Directory of Open Access Journals (Sweden)

    C. Mebarkiaa

    2016-05-01

    Full Text Available In the overall context of the diversification of the use of natural resources, the use of renewable energy including solar photovoltaic has become increasingly indispensable. As such, the development of a new generation of photovoltaic cells based on CuZnSnS4 (CZTS looks promising. Cu2ZnSnS4 (CZTS is a new film absorber, with good physical properties (band gap energy 1.4-1.6 eV [01] with a large absorption coefficient over 104 cm-1. Indeed, the performance of these cells exceeded 30% in recent years.In the present paper, our work based on modeling and numerical simulation, we used SCAPS to study the performance of solar cells based on Cu2ZnSnS4 (CZTS and thus evaluate the electrical efficiency η for typical structures of ZnO / i- ZnO / CdS / CZTS and ITO / ZnO / CdS / CZTS. Furthermore, the influence of the change of CdS by ZnSe buffer layer was treated in this paper.

  20. PREPARATION AND CHARACTERIZATION OF POLY-CRYSTALLINE SILICON THIN FILM

    Institute of Scientific and Technical Information of China (English)

    Y.F. Hu; H. Shen; Z.Y. Liu; L.S. Wen

    2003-01-01

    Poly-crystalline silicon thin film has big potential of reducing the cost of solar cells.In this paper the preparation of thin film is introduced, and then the morphology of poly-crystalline thin film is discussed. On the film we developed poly-crystalline silicon thin film solar cells with efficiency up to 6. 05% without anti-reflection coating.

  1. Thermal Expansion Coefficients of Thin Crystal Films

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The formulas for atomic displacements and Hamiltonian of a thin crystal film in phonon occupation number representation are obtained with the aid of Green's function theory. On the basis of these results, the formulas for thermal expansion coefficients of the thin crystal film are derived with the perturbation theory, and the numerical calculations are carried out. The results show that the thinner films have larger thermal expansion coefficients.

  2. Slip-controlled thin film dynamics

    OpenAIRE

    Fetzer, R.; Rauscher, M; Münch, A.; Wagner, B. A.; Jacobs, K.

    2006-01-01

    In this study, we present a novel method to assess the slip length and the viscosity of thin films of highly viscous Newtonian liquids. We quantitatively analyse dewetting fronts of low molecular weight polystyrene melts on Octadecyl- (OTS) and Dodecyltrichlorosilane (DTS) polymer brushes. Using a thin film (lubrication) model derived in the limit of large slip lengths, we can extract slip length and viscosity. We study polymer films with thicknesses between 50 nm and 230 nm and various tempe...

  3. Optical and Structural Properties of Ultra-thin Gold Films

    CERN Document Server

    Kossoy, Anna; Simakov, Denis; Leosson, Kristjan; Kéna-Cohen, Stéphane; Maier, Stefan A

    2014-01-01

    Realizing laterally continuous ultra-thin gold films on transparent substrates is a challenge of significant technological importance. In the present work, formation of ultra-thin gold films on fused silica is studied, demonstrating how suppression of island formation and reduction of plasmonic absorption can be achieved by treating substrates with (3-mercaptopropyl) trimethoxysilane prior to deposition. Void-free fi lms with deposition thickness as low as 5.4 nm are realized and remain structurally stable at room temperature. Based on detailed structural analysis of the fi lms by specular and diffuse X-ray reflectivity measurements, it is shown that optical transmission properties of continuous ultra-thin films can be accounted for using the bulk dielectric function of gold. However, it is important to take into account the non-abrupt transition zone between the metal and the surrounding dielectrics, which extends through several lattice constants for the laterally continuous ultra-thin films (film thickness...

  4. BDS thin film damage competition

    Energy Technology Data Exchange (ETDEWEB)

    Stolz, C J; Thomas, M D; Griffin, A J

    2008-10-24

    A laser damage competition was held at the 2008 Boulder Damage Symposium in order to determine the current status of thin film laser resistance within the private, academic, and government sectors. This damage competition allows a direct comparison of the current state-of-the-art of high laser resistance coatings since they are all tested using the same damage test setup and the same protocol. A normal incidence high reflector multilayer coating was selected at a wavelength of 1064 nm. The substrates were provided by the submitters. A double blind test assured sample and submitter anonymity so only a summary of the results are presented here. In addition to the laser resistance results, details of deposition processes, coating materials, and layer count will also be shared.

  5. Thin-film optical shutter

    Science.gov (United States)

    Matlow, S. L.

    1981-02-01

    The ideal solution to the excessive solar gain problem is an optical shutter, a device which switches from being highly transmissive to solar radiation to being highly reflective to solar radiation when a critical temperature is reached in the enclosure. The switching occurs because one or more materials in the device undergo a phase transition at the critical temperature. A specific embodiment of macroconjugated macromolecules, the poly (p-phenylene)'s, was chosen as the one most likely to meet all of the requirements of the thin film optical shutter project (TFOS). The reason for this choice is explored. In order to be able to make meaningful calculations of the thermodynamic and optical properties of the poly (p-phenylene)'s a quantum mechanical method, the equilibrium bond length (EBL) theory, was developed. Some results of EBL theory are included.

  6. Thin film bioreactors in space

    Science.gov (United States)

    Hughes-Fulford, M.; Scheld, H. W.

    1989-01-01

    Studies from the Skylab, SL-3 and D-1 missions have demonstrated that biological organisms grown in microgravity have changes in basic cellular functions such as DNA, mRNA and protein synthesis, cytoskeleton synthesis, glucose utilization, and cellular differentiation. Since microgravity could affect prokaryotic and eukaryotic cells at a subcellular and molecular level, space offers an opportunity to learn more about basic biological systems with one inmportant variable removed. The thin film bioreactor will facilitate the handling of fluids in microgravity, under constant temperature and will allow multiple samples of cells to be grown with variable conditions. Studies on cell cultures grown in microgravity would make it possible to identify and quantify changes in basic biological function in microgravity which are needed to develop new applications of orbital research and future biotechnology.

  7. ITO-Free Semitransparent Organic Solar Cells Based on Silver Thin Film Electrodes

    Directory of Open Access Journals (Sweden)

    Zhizhe Wang

    2014-01-01

    Full Text Available ITO-free semitransparent organic solar cells (OSCs based on MoO3/Ag anodes with poly(3-hexylthiophene and [6,6]-phenyl-C61-butyric acid methyl ester films as the active layer are investigated in this work. To obtain the optimal transparent (MoO3/Ag anode, ITO-free reference OSCs are firstly fabricated. The power conversion efficiency (PCE of 2.71% is obtained for OSCs based on the optimal MoO3 (2 nm/Ag (9 nm anode, comparable to that of ITO-based reference OSCs (PCE of 2.85%. Then based on MoO3 (2 nm/Ag (9 nm anode, ITO-free semitransparent OSCs with different thickness combination of Ca and Ag as the cathodes are investigated. It is observed from our results that OSCs with Ca (15 nm/Ag (15 nm cathode have the optimal transparency. Meanwhile, the PCE of 1.79% and 0.67% is obtained for illumination from the anode and cathode side, respectively, comparable to that of similar ITO-based semitransparent OSCs (PCE of 1.59% and 0.75% for illumination from the anode and cathode side, resp. (Sol. Energy Mater. Sol. Cells, 95, pp. 877–880, 2011. The transparency and PCE of ITO-free semitransparent OSCs can be further improved by introducing a light couple layer. The developed method is compatible with various substrates, which is instructive for further research of ITO-free semitransparent OSCs.

  8. Thin film thermocouples for in situ membrane electrode assembly temperature measurements in a polybenzimidazole-based high temperature proton exchange membrane unit cell

    DEFF Research Database (Denmark)

    Ali, Syed Talat; Lebæk, Jesper; Nielsen, Lars Pleth;

    2010-01-01

    This paper presents Type-T thin film thermocouples (TFTCs) fabricated on Kapton (polyimide) substrate for measuring the internal temperature of PBI(polybenzimidazole)-based high temperature proton exchange membrane fuel cell (HT-PEMFC). Magnetron sputtering technique was employed to deposit a 2 m...

  9. Response to simulated typical daily outdoor irradiation conditions of thin-film silicon-based triple-band-gap, triple-junction solar cells

    NARCIS (Netherlands)

    Krishnan, P.; Schuttauf, J.A.; van der Werf, C.H.M.; Houshyani Hassanzadeh, B.; van Sark, W.G.J.H.M.; Schropp, R.E.I.

    2009-01-01

    We studied the response to various realistic outdoor conditions of thin-film silicon-based triple-band-gap, triple-junction cells that were made in house. The triple-junction cells consist of a stack of proto-Si:H/proto-SiGe:H/nanocrystalline (nc)-Si:H cells in an n–i–p configuration, fabricated usi

  10. Durability of VO2-based thin films at elevated temperature: Towards thermochromic fenestration

    Science.gov (United States)

    Ji, Yu-Xia; Niklasson, Gunnar A.; Granqvist, Claes G.

    2014-11-01

    An explorative study was performed on sputter-deposited thermochromic VO2 films with top coatings of Al oxide and Al nitride. The films were exposed to dry air at a high temperature. Bare 80-nm-thick VO2 films rapidly converted to non-thermochromic V2O5 under the chosen conditions. Al oxide top coatings protected the underlying VO2 films and, expectedly, increased film thickness yielded improved protection. Specifically, it was found that a 30-nm-thick sputter-deposited Al oxide top coating delayed the oxidation by more than one day upon heating at 300°C. The results demonstrate the importance of protective layers in thermochromic windows for practical application.

  11. Flexible heterostructures based on metal phthalocyanines thin films obtained by MAPLE

    Science.gov (United States)

    Socol, M.; Preda, N.; Rasoga, O.; Breazu, C.; Stavarache, I.; Stanculescu, F.; Socol, G.; Gherendi, F.; Grumezescu, V.; Popescu-Pelin, G.; Girtan, M.; Stefan, N.

    2016-06-01

    Heterostructures based on zinc phthalocyanine (ZnPc), magnesium phthalocyanine (MgPc) and 5,10,15,20-tetra(4-pyrydil)21H,23H-porphine (TPyP) were deposited on ITO flexible substrates by Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique. Organic heterostructures containing (TPyP/ZnPc(MgPc)) stacked or (ZnPc(MgPc):TPyP) mixed layers were characterized by X-ray diffraction-XRD, photoluminescence-PL, UV-vis and FTIR spectroscopy. No chemical decomposition of the initial materials was observed. The investigated structures present a large spectral absorption in the visible range making them suitable for organic photovoltaics applications (OPV). Scanning electron microscopy-SEM and atomic force microscopy-AFM revealed morphologies typical for the films prepared by MAPLE. The current-voltage characteristics of the investigated structures, measured in dark and under light, present an improvement in the current value (∼3 order of magnitude larger) for the structure based on the mixed layer (Al/MgPc:TPyP/ITO) in comparison with the stacked layer (Al/MgPc//TPyP/ITO). A photogeneration process was evidenced in the case of structures Al/ZnPc:TPyP/ITO with mixed layers.

  12. Comprehensive dielectric performance of bismuth acceptor doped BaTiO3 based nanocrystal thin film capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Liu, SY; Zhang, HN; Sviridov, L; Huang, LM; Liu, XH; Samson, J; Akins, D; Li, J; O' Brien, S

    2012-11-07

    We present a novel approach to preparing bismuth acceptor doped barium titanate nanocrystal formulations that can be deposited in conjunction with polymers in order to prepare a thin film nanocomposite dielectric that exhibits desirable capacitor characteristics. Exploring the limits of dielectric function in nanocomposites is an important avenue of materials research, while paying strict attention to the overall device quality, namely permittivity, loss and equivalent series resistance (ESR). Pushing capacitor function to higher frequencies, a desirable goal from an electrical engineering point of view, presents a new set of challenges in terms of minimizing interfacial, space charge and polarization effects within the dielectric. We show the ability to synthesize BaTi0.96Bi0.04O3 or BaTi0.97Bi0.03O3 depending on nominal molar concentrations of bismuth at the onset. The low temperature solvothermal route allows for substitution at the titanium site (strongly supported by Rietveld and Raman analysis). Characterization is performed by XRD with Rietveld refinement, Raman Spectroscopy, SEM and HRTEM. A mechanism is proposed for bismuth acceptor substitution, based on the chemical reaction of the alkoxy-metal precursors involving nucleophilic addition. Dielectric analysis of the nanocrystal thin films is performed by preparing nanocrystal/PVP 2-2 nanocomposites (no annealing) and comparing BaTi0.96Bi0.04O3 and BaTi0.97Bi0.03O3 with undoped BaTiO3. Improvements of up to 25% in capacitance (permittivity) are observed, with lower loss and dramatically improved ESR, all to very high frequency ranges (>10 MHz).

  13. Organic photo detectors for an integrated thin-film spectrometer

    Science.gov (United States)

    Peters, Sabine; Sui, Yunwu; Glöckler, Felix; Lemmer, Uli; Gerken, Martina

    2007-09-01

    We introduce a thin-film spectrometer that is based on the superprism effect in photonic crystals. While the reliable fabrication of two and three dimensional photonic crystals is still a challenge, the realization of one-dimensional photonic crystals as thin-film stacks is a relatively easy and inexpensive approach. Additionally, dispersive thin-film stacks offer the possibility to custom-design the dispersion profile according to the application. The thin-film stack is designed such that light incident at an angle experiences a wavelength-dependent spatial beam shift at the output surface. We propose the monolithic integration of organic photo detectors to register the spatial beam position and thus determine the beam wavelength. This thin-film spectrometer has a size of approximately 5 mm2. We demonstrate that the output position of a laser beam is determined with a resolution of at least 20 μm by the fabricated organic photo detectors. Depending on the design of the thin-film filter the wavelength resolution of the proposed spectrometer is at least 1 nm. Possible applications for the proposed thin-film spectrometer are in the field of absorption spectroscopy, e.g., for gas analysis or biomedical applications.

  14. Magnetization in permalloy thin films

    Indian Academy of Sciences (India)

    Rachana Gupta; Mukul Gupta; Thomas Gutberlet

    2008-11-01

    Thin films of permalloy (Ni80Fe20) were prepared using an Ar+N2 mixture with magnetron sputtering technique at ambient temperature. The film prepared with only Ar gas shows reflections corresponding to the permalloy phase in X-ray diffraction (XRD) pattern. The addition of nitrogen during sputtering results in broadening of the peaks in XRD pattern, which finally leads to an amorphous phase. The - loop for the sample prepared with only Ar gas is matching well with the values obtained for the permalloy. For the samples prepared with increased nitrogen partial pressure the magnetic moment decreased rapidly and the values of coercivity increased. The polarized neutron reflectivity measurements (PNR) were performed in the sample prepared with only Ar gas and with nitrogen partial pressure of 5 and 10%. It was found that the spin-up and spin-down reflectivities show exactly similar reflectivity for the sample prepared with Ar gas alone, while PNR measurements on 5 and 10% sample show splitting in the spin-up and spin-down reflectivity.

  15. Mixed-state hall effect in Hg- and Tl-based superconducting thin films containing columnar defects

    Science.gov (United States)

    Kang, W. N.; Kim, Wan-Seon; Lee, Sung-Ik; Kang, B. W.; Wu, J. Z.; Chen, Q. Y.; Chu, W. K.; Chu, C. W.

    We have investigated the mixed-state Hall resistivity ρ xy and longitudinal resistivity ρ xx in HgBa 2CaCu 2O 6, HgBa 2Ca 2Cu 3O 8, and Tl 2Ba 2CaCu 2O 8 thin films for various parameters, such as densities of columnar defects, number of CuO 2 planes, and anisotropy ratios, as a function of the magnetic field up to 18 T. The scaling exponent β in ρ xy = Aρ xxβ is 1.9 ± 0.1 in the clean limit (CL) at high fields and low T whereas β is 1 ± 0.1 in the moderately clean limit (MCL) at low fields and high T. We also find the triple sign reversal in the HgBa 2CaCu 2O 6 films containing high-density columnar defects. These results can be interpreted within the context of a recent theory based on the midgap states in the vortex core.

  16. High electron mobility thin-film transistors based on Ga{sub 2}O{sub 3} grown by atmospheric ultrasonic spray pyrolysis at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Stuart R., E-mail: s.thomas09@imperial.ac.uk, E-mail: thomas.anthopoulos@imperial.ac.uk; Lin, Yen-Hung; Faber, Hendrik; Anthopoulos, Thomas D., E-mail: s.thomas09@imperial.ac.uk, E-mail: thomas.anthopoulos@imperial.ac.uk [Department of Physics, Blackett Laboratory, Imperial College London, London SW7 2BW (United Kingdom); Adamopoulos, George [Department of Engineering, Engineering Building, Lancaster University, Bailrigg, Lancaster LA1 4YR (United Kingdom); Sygellou, Labrini [Institute of Chemical Engineering and High Temperature Processes (ICEHT), Foundation of Research and Technology Hellas (FORTH), Stadiou Strasse Platani, P.O. Box 1414, Patras GR-265 04 (Greece); Stratakis, Emmanuel [Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology-Hellas (FORTH), Heraklion 71003 (Greece); Materials Science and Technology Department, University, of Crete, Heraklion 71003 (Greece); Pliatsikas, Nikos; Patsalas, Panos A. [Laboratory of Applied Physics, Department of Physics, Aristotle University of Thessaloniki, Thessaloniki GR-54124 (Greece)

    2014-09-01

    We report on thin-film transistors based on Ga{sub 2}O{sub 3} films grown by ultrasonic spray pyrolysis in ambient atmosphere at 400–450 °C. The elemental, electronic, optical, morphological, structural, and electrical properties of the films and devices were investigated using a range of complementary characterisation techniques, whilst the effects of post deposition annealing at higher temperature (700 °C) were also investigated. Both as-grown and post-deposition annealed Ga{sub 2}O{sub 3} films are found to be slightly oxygen deficient, exceptionally smooth and exhibit a wide energy bandgap of ∼4.9 eV. Transistors based on as-deposited Ga{sub 2}O{sub 3} films show n-type conductivity with the maximum electron mobility of ∼2 cm{sup 2}/V s.

  17. Programmable digital memory devices based on nanoscale thin films of a thermally dimensionally stable polyimide

    International Nuclear Information System (INIS)

    We have fabricated electrically programmable memory devices with thermally and dimensionally stable poly(N-(N',N'-diphenyl-N'-1,4-phenyl)-N,N-4,4'-diphenylene hexafluoroisopropylidene-diphthalimide) (6F-2TPA PI) films and investigated their switching characteristics and reliability. 6F-2TPA PI films were found to reveal a conductivity of 1.0 x 10-13-1.0 x 10-14 S cm-1. The 6F-2TPA PI films exhibit versatile memory characteristics that depend on the film thickness. All the PI films are initially present in the OFF state. The PI films with a thickness of >15 to 10. Therefore, these WORM memory devices can provide an efficient, low-cost means of permanent data storage. On the other hand, the 100 nm thick PI films exhibit excellent dynamic random access memory (DRAM) characteristics with polarity. The ON/OFF current ratio of the DRAM devices is as high as 1011. The observed electrical switching behaviors were found to be governed by trap-limited space-charge-limited conduction and local filament formation and further dependent on the differences between the highest occupied molecular orbital and the lowest unoccupied molecular orbital energy levels of the PI film and the work functions of the top and bottom electrodes as well as the PI film thickness. In summary, the excellent memory properties of 6F-2TPA PI make it a promising candidate material for the low-cost mass production of high density and very stable digital nonvolatile WORM and volatile DRAM memory devices.

  18. Exchange bias in zinc ferrite-FeNiMoB based metallic glass composite thin films

    Energy Technology Data Exchange (ETDEWEB)

    R, Lisha; P, Geetha; B, Aravind P.; Anantharaman, M. R., E-mail: mraiyer@yahoo.com [Cochin University of Science and Technology, Cochin-682022 (India); T, Hysen [Christian College, Chengannur, Kerala-689121 (India); Ojha, S.; Avasthi, D. K. [Inter University Accelerator Centre, Vasant Kunj, New Delhi-110067 (India); Ramanujan, R. V. [School of Materials Science and Engineering, Nanyang Technological University (Singapore)

    2015-06-24

    The Exchange bias phenomenon and methods to manipulate the bias field in a controlled manner are thrust areas in magnetism due to its sophisticated theoretical concepts as well as advanced technological utility in the field of spintronics. The Exchange bias effect is observed as a result of ferromagnetic-antiferromagnetic (FM-AFM) exchange interaction, usually observed as a loop shift on field cooling below the Neel temperature of AFM. In the present study, we have chosen zinc ferrite which is a well known antiferromagnet, and FeNiMoB based metallic glass as the ferromagnet. The films were prepared by RF sputtering technique. The thickness and composition was obtained by RBS. The magnetic studies using SQUID VSM indicate exchange bias effect in the system. The effect of thermal annealing on exchange bias effect was studied. The observed exchange bias in the zinc ferrite-FeNiMoB system is not due to FM-AFM coupling but due to spin glass-ferromagnetic interaction.

  19. Barium strontium titanate thin film varactors for room-temperature microwave device applications

    International Nuclear Information System (INIS)

    Recent progress in the development of barium strontium titanate thin film varactors for room temperature tunable microwave devices applications is reviewed, with emphasis on efforts towards the improvement in the quality of BST thin films and the fabrication issues crucial for the performance of microwave devices based on BST varactors. The paper provides examples of tunable microwave devices employing BST varactors. Other thin film materials currently competing with BST thin films are discussed. Topics which deserve further investigation are suggested. (topical review)

  20. TiO2 thin film photocatalyst

    Institute of Scientific and Technical Information of China (English)

    YU Jiaguo

    2004-01-01

    It is well known that the photocatalytic activity of TiO2 thin films strongly depends on the preparing methods and post-treatment conditions, since they have a decisive influence on the chemical and physical properties of TiO2 thin films.Therefore, it is necessary to elucidate the influence of the preparation process and post-treatment conditions on the photocatalytic activity and surface microstructures of the films. This review deals with the preparation of TiO2 thin film photocatalysts by wet-chemical methods (such as sol-gel, reverse micellar and liquid phase deposition) and the comparison of various preparation methods as well as their advantage and disadvantage. Furthermore, it is discussed that the advancement of photocatalytic activity, super-hydrophilicity and bactericidal activity of TiO2 thin film photocatalyst in recent years.

  1. A non-labeled DNA biosensor based on light addressable potentiometric sensor modified with TiO_2 thin film

    Institute of Scientific and Technical Information of China (English)

    Xiao-lin ZONG; Chun-sheng WU; Xiao-ling WU; Yun-feng LU; Ping WANG

    2009-01-01

    Titanium dioxide (TiO_2) thin film was deposited on the surface of the light addressable potentiometric sensor (LAPS) to modify the sensor surface for the non-labeled detection of DNA molecules. To evaluate the effect of ultraviolet (UV) treatment on the silanization level of TiO_2 thin film by 3-aminopropyltrietboxysilane (APTS), fluorescein isothiocyanate (FITC) was used to label the amine group on the end of APTS immobilized onto the TiO_2 thin film. We found that, with UV irradiation, the silani-zation level of the irradiated area of the TiO_2 film was improved compared with the non-irradiated area under well-controlled conditions. This result indicates that TiO_2 can act as a coating material on the biosensor surface to improve the effect and effi-ciency of the covalent immobilization of biomolecules on the sensor surface. The artificially synthesized probe DNA molecules were covalently linked onto the surface of TiO_2 film. The hybridization of probe DNA and target DNA was monitored by the recording of Ⅰ-Ⅴ curves that shift along the voltage axis during the process of reaction. A significant LAPS signal can be detected at 10 μmol/L of target DNA sample.

  2. Thin liquid film flow and heat transfer under spray impingement

    International Nuclear Information System (INIS)

    A mathematical model was derived to investigate thin liquid film flow under spray impingement. Based on predicted flow patterns, a heat transfer model was developed to investigate the heat transfer performance in the non-boiling regime of spray cooling. The film thickness predicted by the thin film flow model favourably compares with reported experimental results obtained at different measurement locations and nozzle inlet pressures. It is found that the film thickness is sensitive to droplet flux distribution but not the nozzle inlet pressure. The comparison of the heated surface temperature between the proposed heat transfer model and the published experimental data shows good agreement. - Highlights: ► Thin liquid film flow in spray cooling is theoretically studied. ► A thin liquid film flow model is derived to predict the thin film flow pattern under spray impingement. ► A heat transfer model is developed to predict the heat transfer performance in the non-boiling regime of spray cooling. ► Film thickness of the liquid film flow is sensitive to droplet flux distribution but not the nozzle inlet pressure. ► Droplet impingement cooling is the primary cooling mechanism in the non-boiling regime of spray cooling.

  3. Enhanced electrical properties of pentacene-based organic thin-film transistors by modifying the gate insulator surface

    Science.gov (United States)

    Tang, J. X.; Lee, C. S.; Chan, M. Y.; Lee, S. T.

    2008-09-01

    A reliable surface treatment for the pentacene/gate dielectric interface was developed to enhance the electrical transport properties of organic thin-film transistors (OTFTs). Plasma-polymerized fluorocarbon (CFx) film was deposited onto the SiO 2 gate dielectric prior to pentacene deposition, resulting in a dramatic increase of the field-effect mobility from 0.015 cm 2/(V s) to 0.22 cm 2/(V s), and a threshold voltage reduction from -14.0 V to -9.9 V. The observed carrier mobility increase by a factor of 10 in the resulting OTFTs is associated with various growth behaviors of polycrystalline pentacene thin films on different substrates, where a pronounced morphological change occurs in the first few molecular layers but the similar morphologies in the upper layers. The accompanying threshold voltage variation suggests that hole accumulation in the conduction channel-induced weak charge transfer between pentacene and CFx.

  4. Preface: Thin films of molecular organic materials

    Science.gov (United States)

    Fraxedas, J.

    2008-03-01

    /substrate systems (also called heterostructures) based on the physical properties of the bulk materials, usually in the form of single crystals. However, in recent years the thin films community has been continually growing, helping the field to mature. In my opinion two main aspects have advanced the thin molecular films field. The first is the different applications with optical and electrical devices such as OFETs (organic field-effect transistors) and OLEDs (organic light emitting diodes), applications that could not have been achieved with single crystals because of limited size, difficult processability and mechanical fragility. The second is the involvement of the surface science community with their overwhelming arsenal of experimental techniques. From the synthesis point of view, the preparation of thin films is being regarded as a complementary synthesis route. The different externally accessible variables involved in the preparation process (temperature, pressure, molecular flux, distance, time, concentration, solvent, substrate, etc.), which define the so-called parameter hyperspace, can be so diverse when comparing competing synthesis routes (e.g. solution versus vapour growth) that we should not be surprised if different crystallographic phases with different morphologies are obtained, even if metastable. We should not forget here that the amazingly large number of available molecules is due to the longstanding and innovative work of synthesis chemists, a task that has not been sufficiently recognized (laymen in the domain of synthesis of organic molecules tend to believe that almost any molecule can be synthesized). In summary, one of the goals of this issue is to highlight the emerging importance of the field of thin molecular organic films by giving selected examples. It is clear that some important examples are missing, which are due in part to space limitation and to the understandable reluctance of highly-ranked specialists to contribute because of work overload

  5. Scanning tunneling spectroscopy of Pb thin films

    Energy Technology Data Exchange (ETDEWEB)

    Becker, Michael

    2010-12-13

    films. It is shown how accurate quantitative information about work function differences can be obtained and how these differences depend on the QWSs in the Pb thin films. The electron transport properties and mechanical characteristics of atom-sized metallic contacts are of fundamental interest in view of future nanoscale device technologies. Proximity probes like STM, metal break junctions, and related techniques, together with computational methods for simulating tip-sample interactions, have made it possible to address this question. While the importance of atomic structure and bonding for transport through single-atom junctions has repeatedly been emphasized, investigations of the influence of subsurface bonding properties have been rare. Here, the contact formation of a STM tip approaching Pb(111) thin films supported on Ag(111) substrates is investigated. Contacts on monolayer films are found to differ from contacts made on thicker Pb films. This behavior is explained in terms of different vertical bonding-strengths due to a charge-transfer induced surface dipole. Furthermore, the single-atom contact conductance on Pb(111) films beyond the first monolayer is determined. It is shown that analyses based on hitherto widely used conventional conductance histograms may overestimate the single-atom contact conductance by as much as 20%. (orig.)

  6. Alumina Thin Film Growth: Experiments and Modeling

    OpenAIRE

    Wallin, Erik

    2007-01-01

    The work presented in this thesis deals with experimental and theoretical studies related to the growth of crystalline alumina thin films. Alumina, Al2O3, is a polymorphic material utilized in a variety of applications, e.g., in the form of thin films. Many of the possibilities of alumina, and the problems associated with thin film synthesis of the material, are due to the existence of a range of different crystalline phases. Controlling the formation of the desired phase and the transformati...

  7. Electrochromism of amorphous ruthenium oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Se-Hee; Liu, Ping; Tracy, C. Edwin; Deb, Satyen K. [National Renewable Energy Laboratory, Center for Basic Sciences, 1617 Cole Boulevard, Golden, CO 80401 (United States); Cheong, Hyeonsik M. [Sogang University, Shinsoo-Dong, Seoul 121-742 (Korea, Republic of)

    2003-12-01

    We report on the electrochromic behavior of amorphous ruthenium oxide thin films and their electrochemical characteristics for use as counterelectrodes for electrochromic devices. Hydrous ruthenium oxide thin films were prepared by cyclic voltammetry on ITO coated glass substrates from an aqueous ruthenium chloride solution. The cyclic voltammograms of this material show the capacitive behavior including two redox reaction peaks in each cathodic and anodic scan. The ruthenium oxide thin film electrode exhibits a 50% modulation of optical transmittance at 670 nm wavelength with capacitor charge/discharge.

  8. Quartz crystal microbalance thin-film dissolution rate monitor

    Science.gov (United States)

    Hinsberg, William D.; Kanazawa, Kay K.

    1989-03-01

    We describe the details of construction and operation of an instrument useful for the characterization of dissolution kinetics of thin films. This device, based on a quartz crystal microbalance operating in contact with a liquid, avoids the limitations associated with the use of optical, electrical, and mechanical dissolution rate measurement techniques. The QCM rate monitor has general application to the measurement of the kinetics of dissolution of transparent and opaque thin films such as dielectrics, metals, and polymeric resists.

  9. Scanned probe microscopy for thin film superconductor development

    Energy Technology Data Exchange (ETDEWEB)

    Moreland, J. [National Institute of Standards and Technology, Boulder, CO (United States)

    1996-12-31

    Scanned probe microscopy is a general term encompassing the science of imaging based on piezoelectric driven probes for measuring local changes in nanoscale properties of materials and devices. Techniques like scanning tunneling microscopy, atomic force microscopy, and scanning potentiometry are becoming common tools in the production and development labs in the semiconductor industry. The author presents several examples of applications specific to the development of high temperature superconducting thin films and thin-film devices.

  10. Research and developments in thin film silicon photovoltaics

    OpenAIRE

    Despeisse, M; Ballif, C.; Feltrin, A.; Meillaud, F.; Fay, S.; F.-J. Haug, F.-J.; Dominé, D.; Python, M.; Soderstrom, T.; Buehlmann, P; Bugnon, G.; Parascandolo, G

    2009-01-01

    The increasing demand for photovoltaic devices and the associated crystalline silicon feedstock demand scenario have led in the past years to the fast growth of the thin film silicon industry. The high potential for cost reduction and the suitability for building integration have initiated both industrial and research laboratories dynamisms for amorphous silicon and micro-crystalline silicon based photovoltaic technologies. The recent progress towards higher efficiencies thin film silicon sol...

  11. Growth of cuprate high temperature superconductor thin films

    Directory of Open Access Journals (Sweden)

    H-U Habermeier

    2006-09-01

    Full Text Available   This paper reviews briefly the development of physical vapour deposition based HTS thin film preparation technologies to today’s state-of-the-art methods. It covers the main trends of in-situ process and growth control. The current activities to fabricate tapes for power applications as well as to tailor interfaces in cuprate are described. Some future trends in HTS thin film research, both for science as well as application driven activities are outlined.

  12. High efficiency cadmium and zinc telluride-based thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Rohatgi, A.; Summers, C.J.; Erbil, A.; Sudharsanan, R.; Ringel, S. (Georgia Inst. of Tech., Atlanta, GA (USA). School of Electrical Engineering)

    1990-10-01

    Polycrystalline Cd{sub 1-x}Zn{sub x}Te and Cd{sub 1-x}Mn{sub x}Te films with a band gap of 1.7 eV were successfully grown on glass/SnO{sub 2}/CdS substrates by molecular beam epitaxy (MBE) and metal-organic chemical vapor deposition (MOCVD), respectively. Polycrystalline Cd{sub 1-x}Zn{sub x}Te films grown by MBE resulted in uniform composition and sharp interfaces. However, polycrystalline Cd{sub 1-x}Mn{sub x}Te films grown by MOCVD showed nonuniform compositions and evidence of manganese accumulation at the Cd{sub 1-x}Mn{sub x}Te/CdS interface. We found that manganese interdiffuses and replaces cadmium in the CdS film. By improving the CdTe/CdS interface and, thus, reducing the collection function effects, the efficiency of the MOCVD CdTe cell can be improved to about 13.5%. MBE-grown CdTe cells also produced 8%--9% efficiencies. The standard CdTe process was not optimum for ternary films and resulted in a decrease in the band gap. Recent results indicate that CdCl{sub 2} + ZnCl{sub 2} chemical treatment may prevent the band-gap reduction, and that chromate etch (rather than bromine etch) may provide the solution to contact resistance in the ternary cells.

  13. High efficiency cadmium and zinc telluride-based thin film solar cells

    Science.gov (United States)

    Rohatgi, A.; Summers, C. J.; Erbil, A.; Sudharsanan, R.; Ringel, S.

    1990-10-01

    Polycrystalline Cd(1-x)Zn(x)Te and Cd(1-x)Mn(x)Te films with a band gap of 1.7 eV were successfully grown on glass/SnO2/CdS substrates by molecular beam epitaxy (MBE) and metal-organic chemical vapor deposition (MOCVD), respectively. Polycrystalline Cd(1-x)Zn(x)Te films grown by MBE resulted in uniform composition and sharp interfaces. However, polycrystalline Cd(1-x)Mn(x)Te films grown by MOCVD showed nonuniform compositions and evidence of manganese accumulation at the Cd(1-x)Mn(x)Te/CdS interface. We found that manganese interdiffuses and replaces cadmium in the CdS film. By improving the CdTe/CdS interface and, thus, reducing the collection function effects, the efficiency of the MOCVD CdTe cell can be improved to about 13.5 percent. MBE-grown CdTe cells also produced 8 to 9 percent efficiencies. The standard CdTe process was not optimum for ternary films and resulted in a decrease in the band gap. Recent results indicate that CdCl2 + ZnCl2 chemical treatment may prevent the band-gap reduction, and that chromate etch (rather than bromine etch) may provide the solution to contact resistance in the ternary cells.

  14. Memristive switching in vanadium dioxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Buerger, Danilo; John, Varun; Kovacs, Gyoergy; Skorupa, Ilona; Helm, Manfred; Schmidt, Heidemarie [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany)

    2011-07-01

    Memristive devices exhibit an improved performance at ultra-small scales. The microscopic model for memristive behavior in oxide nanostructures often depends on the distribution of oxygen vacancies and is determined by the cation species. In 2008 HP presented the first bipolar TiO2-based memristor for resistive applications, where the drift of oxygen vacancies causes a change in the resistance of ultrathin TiO2 films which can be locally modified by ion implantation. We prepared vanadium dioxide (VO2) thin films with the reversible metal-insulator phase transition at the thermochromic switching temperature of around 340 K by pulsed laser deposition on (0001)-sapphire substrates and analyzed the electric-pulse-induced thermochromic switching in the VO2 gap region at room temperature due to local heating. As a result, we find the typical pinched hysteresis loop of a memristor, a repeatable switching behavior for billions of voltage pulses and switching times shorter than 50 ns in VO2 thin films.

  15. Nano porous Al2O3-TiO2 thin film based humidity sensor prepared by spray pyrolysis technique

    Science.gov (United States)

    Chandrashekara, H. D.; Angadi, Basavaraj; Ravikiran, Y. T.; Poornima, P.; Shashidhar, R.; Murthy, L. C. S.

    2016-05-01

    The nano porous surface structured TiO2 and Al2O3-TiO2 thin films were prepared using spray pyrolysis technique at 350°C. The XRD pattern of Al2O3-TiO2 film shows anatase phase and mixed phase of Al2TiO5. The surface morphology of films show a uniformly distributed nano porous structure. The elemental analysis through EDAX shows good stoichiometry. The sensitivity for humidity sensing were determined for both films of TiO2 and Al2O3-TiO2 and corresponding values are found to be 74.2% and 84.02%, this result reveal that Al2O3-TiO2 films shows higher sensing percent than the TiO2 due to the nano porous surface nature. The Al2O3-TiO2 film shows fast response time and long recovery time than the TiO2 film, this may be due to the meso-porous morphology of these films.

  16. Insect thin films as solar collectors.

    Science.gov (United States)

    Heilman, B D; Miaoulis, L N

    1994-10-01

    A numerical method for simulation of microscale radiation effects in insect thin-film structures is described. Accounting for solar beam and diffuse radiation, the model calculates the reflectivity and emissivity of such structures. A case study examines microscale radiation effects in butterfuly wings, and results reveal a new function of these multilayer thin films: thermal regulation. For film thicknesses of the order of 0.10 µm, solar absorption levels vary by as much as 25% with small changes in film thickness; for certain existing structures, absorption levels reach 96%., This is attributed to the spectral distribution of the reflected radiation, which consists of a singular reflectance peak within the solar spectrum.

  17. Visible-light photochromic nanocomposite thin films based on polyvinylpyrrolidone and polyoxometalates supported on clay minerals

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Hybrid film was synthesized by entrapping PMoA supported on the Na-MMT into PVPd. • Na-MMT performed the function of excellent dispersion. • The hybrid film had good visible-light photochromic properties. • The photo-reduction process occurred according to the proton transfer mechanism. - Abstract: A novel reversible photochromic nanocomposite film was prepared by entrapping phosphomolybdic acid supported on the sodium bentonite (PMoA/Na-MMT) into polyvinylpyrrolidone (PVPd). The microstructure, thermal stability, photochromic behavior and mechanism of the hybrid film were investigated. Fourier transform infrared spectroscopy (FT-IR) results illustrated that the Keggin geometry of polyoxometalates (PMoA) and organic groups of PVPd were still preserved inside the composites and non-covalent bond interaction was built between PMoA/Na-MMT and PVPd polymer matrix. Transmission electron microscopy (TEM) image showed that PMoA nanoparticles were finely dispersed in Na-MMT which exhibited fine stratified structure. Atomic force microscopy (AFM) images indicated that the surface topography of polymeric matrix changed after adding PMoA/Na-MMT, and the surface appearance of nanocomposite film was different before and after visible-light irradiation. The stability of the hybrid film and the effect of the perturbation of Na-MMT on the stability were determined by means of the thermogravimetric analysis (TG) and differential thermal analysis (DTA). Irradiated with visible light, the ultraviolet-–visible spectra (UV–vis) showed that the hybrid films changed from colorless to blue and could recover the colorless state gradually in air, where oxygen played an important role during the bleaching process. The hybrid films exhibited excellent bleaching ability during the heating. According to the X-ray photoelectron spectroscopy (XPS) analysis, the appearance of Mo5+ species indicated the photo-reduction reaction between PMoA/Na-MMT and

  18. Visible-light photochromic nanocomposite thin films based on polyvinylpyrrolidone and polyoxometalates supported on clay minerals

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiang-yu; Dong, Qi [Key Lab of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun 130021 (China); Meng, Qing-ling [Key Laboratory of Songliao Aquatic Environment, Ministry of Education, Jilin Jianzhu University, Changchun 130118 (China); Yang, Jun-Yan [Key Lab of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun 130021 (China); Feng, Wei, E-mail: weifeng@jlu.edu.cn [Key Lab of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun 130021 (China); Han, Xiang-kui [Key Laboratory of Songliao Aquatic Environment, Ministry of Education, Jilin Jianzhu University, Changchun 130118 (China)

    2014-10-15

    Graphical abstract: - Highlights: • Hybrid film was synthesized by entrapping PMoA supported on the Na-MMT into PVPd. • Na-MMT performed the function of excellent dispersion. • The hybrid film had good visible-light photochromic properties. • The photo-reduction process occurred according to the proton transfer mechanism. - Abstract: A novel reversible photochromic nanocomposite film was prepared by entrapping phosphomolybdic acid supported on the sodium bentonite (PMoA/Na-MMT) into polyvinylpyrrolidone (PVPd). The microstructure, thermal stability, photochromic behavior and mechanism of the hybrid film were investigated. Fourier transform infrared spectroscopy (FT-IR) results illustrated that the Keggin geometry of polyoxometalates (PMoA) and organic groups of PVPd were still preserved inside the composites and non-covalent bond interaction was built between PMoA/Na-MMT and PVPd polymer matrix. Transmission electron microscopy (TEM) image showed that PMoA nanoparticles were finely dispersed in Na-MMT which exhibited fine stratified structure. Atomic force microscopy (AFM) images indicated that the surface topography of polymeric matrix changed after adding PMoA/Na-MMT, and the surface appearance of nanocomposite film was different before and after visible-light irradiation. The stability of the hybrid film and the effect of the perturbation of Na-MMT on the stability were determined by means of the thermogravimetric analysis (TG) and differential thermal analysis (DTA). Irradiated with visible light, the ultraviolet-–visible spectra (UV–vis) showed that the hybrid films changed from colorless to blue and could recover the colorless state gradually in air, where oxygen played an important role during the bleaching process. The hybrid films exhibited excellent bleaching ability during the heating. According to the X-ray photoelectron spectroscopy (XPS) analysis, the appearance of Mo{sup 5+} species indicated the photo-reduction reaction between PMo

  19. Antimony selenide thin-film solar cells

    Science.gov (United States)

    Zeng, Kai; Xue, Ding-Jiang; Tang, Jiang

    2016-06-01

    Due to their promising applications in low-cost, flexible and high-efficiency photovoltaics, there has been a booming exploration of thin-film solar cells using new absorber materials such as Sb2Se3, SnS, FeS2, CuSbS2 and CuSbSe2. Among them, Sb2Se3-based solar cells are a viable prospect because of their suitable band gap, high absorption coefficient, excellent electronic properties, non-toxicity, low cost, earth-abundant constituents, and intrinsically benign grain boundaries, if suitably oriented. This review surveys the recent development of Sb2Se3-based solar cells with special emphasis on the material and optoelectronic properties of Sb2Se3, the solution-based and vacuum-based fabrication process and the recent progress of Sb2Se3-sensitized and Sb2Se3 thin-film solar cells. A brief overview further addresses some of the future challenges to achieve low-cost, environmentally-friendly and high-efficiency Sb2Se3 solar cells.

  20. Architecture for the semi-automatic fabrication and assembly of thin-film based dielectric elastomer actuators

    Science.gov (United States)

    Randazzo, M.; Buzio, R.; Metta, G.; Sandini, G.; Valbusa, U.

    2008-03-01

    One problem related to the actuation principle of macroscopic dielectric elastomer actuators is the high voltage required, typically in the Kilovolt range, that imposes particular care in the insulation of the whole actuator from the surrounding environment. This high actuation voltage, however, can be drastically reduced if a thin film of dielectric elastomer is used. Despite this, the manufacture of a macroscopic stack-like actuator, starting from thin films of dielectric elastomer can present many manufacture difficulties, like the handling and the assembly of the films, the power distribution to hundreds or thousands of layers, the presence of defects in one single layer that can cause the complete failure of the whole actuator. In this paper, a fast, semi-automatic process is proposed for the manufacture of modular units of dielectric elastomer, each of them consisting of many layers of rolled thin dielectric film. All the manufactured units are independent and take their power from a lateral, compliant supply rail that contacts the sides the electroded layers. This design is very suitable for industrial production: each module can be independently tested and then assembled in a complete macroscopic actuator composed by an unlimited number of these modules. The simple assembly methodology and the semi-automatic manufacture process described in this paper allows the fabrication of multilayer stacked devices, that can be used both as contractile or expanding actuators.

  1. On-Chip Sensing of Thermoelectric Thin Film's Merit.

    Science.gov (United States)

    Xiao, Zhigang; Zhu, Xiaoshan

    2015-01-01

    Thermoelectric thin films have been widely explored for thermal-to-electrical energy conversion or solid-state cooling, because they can remove heat from integrated circuit (IC) chips or micro-electromechanical systems (MEMS) devices without involving any moving mechanical parts. In this paper, we report using silicon diode-based temperature sensors and specific thermoelectric devices to characterize the merit of thermoelectric thin films. The silicon diode temperature sensors and thermoelectric devices were fabricated using microfabrication techniques. Specifically, e-beam evaporation was used to grow the thermoelectric thin film of Sb2Te3 (100 nm thick). The Seebeck coefficient and the merit of the Sb2Te3 thin film were measured or determined. The fabrication of silicon diode temperature sensors and thermoelectric devices are compatible with the integrated circuit fabrication. PMID:26193272

  2. Development of diamond thin film-based alpha particle detectors for online assay of plutonium content in corrosive liquid medium

    International Nuclear Information System (INIS)

    In the present work, diamond thin films were prepared using microwave plasma chemical vapor deposition (MPCVD) method and characterized using XRD, OES, SEM, Raman spectroscopy and I-V techniques. These films were subjected to annealing and chemical cleaning for further improving the film quality. Surface metallization was obtained by gold deposition using PVD. These films were configured in semiconductor-insulator-metal heterostructure and mounted in SS shells. Gold coated growth surface (detector's active area) was sealed by chemical resistant sealing. Suitable bias was applied between the front and back electrical contacts to enable charge collection generated upon alpha particle interaction with diamond. The photograph of developed detector in the lab is shown

  3. Visible blind ultraviolet photodetector based on CH3NH3PbCl3 thin film.

    Science.gov (United States)

    Wang, Wenzhen; Xu, Haitao; Cai, Jiang; Zhu, Jiabin; Ni, Chaowei; Hong, Feng; Fang, Zebo; Xu, Fuzong; Cui, Siwei; Xu, Run; Wang, Linjun; Xu, Fei; Huang, Jian

    2016-04-18

    We report a prototypical device of CH3NH3PbCl3 film ultraviolet photodetectors that were fabricated with a coplanar metal-semiconductor-metal Au interdigital electrode configuration. Pure phase CH3NH3PbCl3 films with a good crystallinity were formed by a hybrid sequential deposition process featured with inter-diffusion of PbCl2 and CH3NH3Cl upon annealing. The CH3NH3PbCl3 film photodetector exhibits a high responsivity of 7.56 A /W at 360 nm, a ultraviolet/visible rejection ratio (R360 nm/R500 nm) was about two orders of magnitude and fast response speed with a rising time of 170 μs and a decay time of 220 μs. All the above results demonstrate CH3NH3PbCl3 film photodetector as a competitive candidate in the application of visible blind UV detectors.

  4. Electrical Resistance Tomography of Conductive Thin Films

    CERN Document Server

    Cultrera, Alessandro

    2016-01-01

    The Electrical Resistance Tomography (ERT) technique is applied to the measurement of sheet conductance maps of both uniform and patterned conductive thin films. Images of the sheet conductance spatial distribution, and local conductivity values are obtained. Test samples are tin oxide films on glass substrates, with electrical contacts on the sample boundary, some samples are deliberately patterned in order to induce null conductivity zones of known geometry while others contain higher conductivity inclusions. Four-terminal resistance measurements among the contacts are performed with a scanning setup. The ERT reconstruction is performed by a numerical algorithm based on the total variation regularization and the L-curve method. ERT correctly images the sheet conductance spatial distribution of the samples. The reconstructed conductance values are in good quantitative agreement with independent measurements performed with the van der Pauw and the four-point probe methods.

  5. Levan nanostructured thin films by MAPLE assembling.

    Science.gov (United States)

    Sima, Felix; Mutlu, Esra Cansever; Eroglu, Mehmet S; Sima, Livia E; Serban, Natalia; Ristoscu, Carmen; Petrescu, Stefana M; Oner, Ebru Toksoy; Mihailescu, Ion N

    2011-06-13

    Synthesis of nanostructured thin films of pure and oxidized levan exopolysaccharide by matrix-assisted pulsed laser evaporation is reported. Solutions of pure exopolysaccharides in dimethyl sulfoxide were frozen in liquid nitrogen to obtain solid cryogenic pellets that have been used as targets in pulsed laser evaporation experiments with a KrF* excimer source. The expulsed material was collected and assembled onto glass slides and Si wafers. The contact angle studies evidenced a higher hydrophilic behavior in the case of oxidized levan structures because of the presence of acidic aldehyde-hydrogen bonds of the coating formed after oxidation. The obtained films preserved the base material composition as confirmed by Fourier transform infrared spectroscopy. They were compact with high specific surface areas, as demonstrated by scanning electron and atomic force microscopy investigations. In vitro colorimetric assays revealed a high potential for cell proliferation for all coatings with certain predominance for oxidized levan. PMID:21520921

  6. Separation Efficiency of Thin-film Evaporators

    Institute of Scientific and Technical Information of China (English)

    R.Billet

    2004-01-01

    The recovery of contaminants and useful substances from liquid wastes, the purification of production effluents and the separation of thermally instable mixtures are some of the multivarious applications of thin-film distillors in many processes of the chemical and allied industries and of the food industries. In a study carried out in pilot plants with distillation test systems there was found a good agreement between the experimental separation results and those obtained by computing with a theorectical model; the latter is based on the assumption of phase equilibrium between the vapour formed on an infinitely small element of area in a liquid film of any given concentric periphery of the vertically arranged evaporator. These tests were perfomed under various phase loads.

  7. A general water-based precursor solution approach to deposit earth abundant Cu2ZnSn(S,Se)4 thin film solar cells

    Science.gov (United States)

    Yang, Yanchun; Kang, Xiaojiao; Huang, Lijian; Wei, Song; Pan, Daocheng

    2016-05-01

    Earth abundant Cu2ZnSn(S,Se)4 (CZTSSe) has been considered as one of the most promising thin film solar cell absorber candidates. Here, we develop a facile water-based precursor solution approach for depositing high-efficiency Cu2ZnSn(S,Se)4 thin film solar cells. In this environmentally friendly approach, inexpensive elemental Cu, Zn, Sn and S powders are used as the starting materials and are dissolved in the aqueous solution of thioglycolic acid and methylamine, forming a homogeneous precursor solution for depositing Cu2ZnSnS4 nanocrystal thin film. As-deposited CZTS nanocrystal thin films are selenized to form the large-grain CZTSSe absorber layers. It was found that Na doping plays an important role in the formation of the extremely dense and flat CZTSSe absorber layer, and fill factor can be significantly improved for Na-doped CZTSSe solar cells, which lead to a photoelectric conversion efficiency of 6.96% with an open-circuit voltage of 378 mV, a short current density of 28.17 mA cm-2, and a fill factor of 65.4%.

  8. Epitaxial growth of CeO2 thin film on cube textured NiW substrate using a propionate-based metalorganic deposition (MOD) method

    International Nuclear Information System (INIS)

    Highlights: ► Accurate study of decomposition of cerium propionate based precursors. ► Epitaxial CeO2 thin film on Ni–W substrate in a reducing atmosphere. ► The films exhibit a high degree of epitaxy within the Dimos criteria. ► The obtained CeO2 films are appropriate for YBCO based coated conductor application. - Abstract: The CeO2 films were epitaxially grown on (0 0 1)[1 0 0]Ni–W biaxially textured substrate using a propionate-based metalorganic deposition (MOD) method. The as deposited CeO2 films exhibit a sharp biaxial texture, with a full width at half maximum (FWHM) of φ and ω-scans of about 7.15° and 7.8°, respectively. The in-plane and out-of plane epitaxial relationship are [0 0 1]CeO2//[0 0 1]Ni–W and [1 0 0]CeO2//[1 1 0]Ni–W, respectively. The morphology of the films is strongly correlated with the film thickness and crystallization temperature. Thus, the 0.3 μm thick film crystallized at 1100 °C has a smooth surface free of cracks or voids with a root mean square roughness (RMS) of about 2.5 nm, whilst the 1.1 μm thick film presents many cracks and a low density of voids. The cracks along the substrate grain boundaries observed in the thicker films take place in the already crystallized film during the rapid cooling process due to difference between the thermal expansion coefficients of the film and metallic Ni–W substrate.

  9. Post-CMOS FinFET integration of bismuth telluride and antimony telluride thin-film-based thermoelectric devices on SoI substrate

    KAUST Repository

    Aktakka, Ethem Erkan

    2013-10-01

    This letter reports, for the first time, heterogeneous integration of bismuth telluride (Bi2Te3) and antimony telluride (Sb 2Te3) thin-film-based thermoelectric ffect transistors) via a characterized TE-film coevaporationand shadow-mask patterning process using predeposition surface treatment methods for reduced TE-metal contact resistance. As a demonstration vehicle, a 2 × 2 mm2-sized integrated planar thermoelectric generator (TEG) is shown to harvest 0.7 μ W from 21-K temperature gradient. Transistor performance showed no significant change upon post-CMOS TEG integration, indicating, for the first time, the CMOS compatibility of the Bi2Te3 and Sb2Te3 thin films, which could be leveraged for realization of high-performance integrated micro-TE harvesters and coolers. © 2013 IEEE.

  10. Highly stretchable wrinkled gold thin film wires

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Joshua, E-mail: joshuk7@uci.edu; Park, Sun-Jun; Nguyen, Thao [Department of Chemical Engineering and Materials Science, University of California, Irvine, California 92697 (United States); Chu, Michael [Department of Biomedical Engineering, University of California, Irvine, California 92697 (United States); Pegan, Jonathan D. [Department of Materials and Manufacturing Technology, University of California, Irvine, California 92697 (United States); Khine, Michelle, E-mail: mkhine@uci.edu [Department of Chemical Engineering and Materials Science, University of California, Irvine, California 92697 (United States); Department of Biomedical Engineering, University of California, Irvine, California 92697 (United States)

    2016-02-08

    With the growing prominence of wearable electronic technology, there is a need to improve the mechanical reliability of electronics for more demanding applications. Conductive wires represent a vital component present in all electronics. Unlike traditional planar and rigid electronics, these new wearable electrical components must conform to curvilinear surfaces, stretch with the body, and remain unobtrusive and low profile. In this paper, the piezoresistive response of shrink induced wrinkled gold thin films under strain demonstrates robust conductive performance in excess of 200% strain. Importantly, the wrinkled metallic thin films displayed negligible change in resistance of up to 100% strain. The wrinkled metallic wires exhibited consistent performance after repetitive strain. Importantly, these wrinkled thin films are inexpensive to fabricate and are compatible with roll to roll manufacturing processes. We propose that these wrinkled metal thin film wires are an attractive alternative to conventional wires for wearable applications.

  11. Thin films for geothermal sensing: Final report

    Energy Technology Data Exchange (ETDEWEB)

    1987-09-01

    The report discusses progress in three components of the geothermal measurement problem: (1) developing appropriate chemically sensitive thin films; (2) discovering suitably rugged and effective encapsulation schemes; and (3) conducting high temperature, in-situ electrochemical measurements. (ACR)

  12. Electroless plating of thin gold films directly onto silicon nitride thin films and into micropores.

    Science.gov (United States)

    Whelan, Julie C; Karawdeniya, Buddini Iroshika; Bandara, Y M Nuwan D Y; Velleco, Brian D; Masterson, Caitlin M; Dwyer, Jason R

    2014-07-23

    A method to directly electrolessly plate silicon-rich silicon nitride with thin gold films was developed and characterized. Films with thicknesses coating planar, curved, and line-of-sight-obscured silicon nitride surfaces. PMID:24999923

  13. ZnO-based thin film transistors employing aluminum titanate gate dielectrics deposited by spray pyrolysis at ambient air.

    Science.gov (United States)

    Afouxenidis, Dimitrios; Mazzocco, Riccardo; Vourlias, Georgios; Livesley, Peter J; Krier, Anthony; Milne, William I; Kolosov, Oleg; Adamopoulos, George

    2015-04-01

    The replacement of SiO2 gate dielectrics with metal oxides of higher dielectric constant has led to the investigation of a wide range of materials with superior properties compared with SiO2. Despite their attractive properties, these high-k dielectrics are usually manufactured using costly vacuum-based techniques. To overcome this bottleneck, research has focused on the development of alternative deposition methods based on solution-processable metal oxides. Here we report the application of spray pyrolysis for the deposition and investigation of Al2x-1·TixOy dielectrics as a function of the [Ti(4+)]/[Ti(4+)+2·Al(3+)] ratio and their implementation in thin film transistors (TFTs) employing spray-coated ZnO as the active semiconducting channels. The films are studied by UV-visible absorption spectroscopy, spectroscopic ellipsometry, impedance spectroscopy, atomic force microscopy, X-ray diffraction and field-effect measurements. Analyses reveal amorphous Al2x-1·TixOy dielectrics that exhibit a wide band gap (∼4.5 eV), low roughness (∼0.9 nm), high dielectric constant (k ∼ 13), Schottky pinning factor S of ∼0.44 and very low leakage currents (<5 nA/cm(2)). TFTs employing stoichiometric Al2O3·TiO2 gate dielectrics and ZnO semiconducting channels exhibit excellent electron transport characteristics with low operating voltages (∼10 V), negligible hysteresis, high on/off current modulation ratio of ∼10(6), subthreshold swing (SS) of ∼550 mV/dec and electron mobility of ∼10 cm(2) V(-1) s(-1). PMID:25774574

  14. Low-Concentration NO2 Gas Sensor Based on HfO2 Thin Films Irradiated by Ultraviolet Light

    Science.gov (United States)

    Karaduman, Irmak; Barin, Özlem; Özer, Metin; Acar, Selim

    2016-08-01

    In this work, we investigate the gas-sensing properties of HfO2 thin films enhanced by ultraviolet (UV) light irradiation. The films were deposited on silicon substrate by atomic layer deposition (ALD) and annealed at 800°C. X-ray diffraction (XRD) and atomic force microscopy (AFM) were used for characterization of the samples, which revealed that the degree of crystallinity and electrical properties of the HfO2 thin films were affected by the annealing temperature. Different film thicknesses (20 nm and 10 nm) were used for gas-sensing measurements. The gas-sensing properties of the films were affected by the UV irradiation time, with improvements in sensor properties observed for samples with more than 30 min of irradiation. The maximum response was found for the 10-nm sensor annealed at 800°C. Moreover, a linear dependence on NO2 concentration was observed for the response, suggesting that the sensing layer is highly suitable for detecting NO2 gas concentrations as low as 1 ppm.

  15. Epitaxy, thin films and superlattices

    International Nuclear Information System (INIS)

    This report is the result of structural investigations of 3d transition metal superlattices consisting of Fe/V, Cr/Mn, V/Mn and Fe/Mn, and a structural and magnetic study of a series of Ho/Pr alloys. The work includes preparation and characterization of substrates as well as growth of thin films and Fe/V superlattices by molecular beam epitaxy, including in-situ characterization by reflection high energy electron diffraction and Auger electron spectroscopy. Structural characterization has been done by x-ray diffraction and neutron diffraction. The x-ray diffraction experiments have been performed on the rotating copper anode at Risoe, and at synchrotron facilities in Hamburg and Brookhaven, and the neutron scattering was done at the Danish research reactor DR3 at Risoe. In addition to longitudinal scans, giving information about the structural parameters in the modulation direction, non-specular scans were also performed. This type of scans gives information about in-plane orientation and lattice parameters. From the analysis, structural information is obtained about lattice parameters, epitaxial strain, coherence lengths and crystallographic orientation for the superlattice systems, except Fe/Mn superlattices, which could not be modelled. For the Ho/Pr alloys, x-ray magnetic scattering was performed, and the crystal and magnetic structure was investigated. (au)

  16. Superconducting thin-film gradiometer

    International Nuclear Information System (INIS)

    We describe the design, fabrication, and performance of planar thin-film dc SQUID's and planar gradiometers in which a dc SQUID is incorporated as a null detector. Each gradiometer was fabricated on a planar substrate and measured an off-diagonal component of changes in the magnetic field gradient. The gradiometer with the highest sensitivity had 127 x 33-mm loops that could be connected in parallel or in series: The sensitivities were 2.1 x 10-13 and 3.7 x 10-13 T m-1 Hz/sup -1/2/, respectively. The intrinsic balance of the gradiometers was about 100 ppm for fields parallel to their plane, and a balance of about 1 ppm could be achieved for fields perpendicular to their plane. When the series-loop gradiometer was rotated through 3600 in the earth's field, the output returned to its initial value to within an amount corresponding to a balance of 1 ppm. Possible improvements in sensitivity are discussed

  17. Polycrystalline-thin-film thermophotovoltaic cells

    Science.gov (United States)

    Dhere, Neelkanth G.

    1996-02-01

    Thermophotovoltaic (TPV) cells convert thermal energy to electricity. Modularity, portability, silent operation, absence of moving parts, reduced air pollution, rapid start-up, high power densities, potentially high conversion efficiencies, choice of a wide range of heat sources employing fossil fuels, biomass, and even solar radiation are key advantages of TPV cells in comparison with fuel cells, thermionic and thermoelectric convertors, and heat engines. The potential applications of TPV systems include: remote electricity supplies, transportation, co-generation, electric-grid independent appliances, and space, aerospace, and military power applications. The range of bandgaps for achieving high conversion efficiencies using low temperature (1000-2000 K) black-body or selective radiators is in the 0.5-0.75 eV range. Present high efficiency convertors are based on single crystalline materials such as In1-xGaxAs, GaSb, and Ga1-xInxSb. Several polycrystalline thin films such as Hg1-xCdxTe, Sn1-xCd2xTe2, and Pb1-xCdxTe, etc., have great potential for economic large-scale applications. A small fraction of the high concentration of charge carriers generated at high fluences effectively saturates the large density of defects in polycrystalline thin films. Photovoltaic conversion efficiencies of polycrystalline thin films and PV solar cells are comparable to single crystalline Si solar cells, e.g., 17.1% for CuIn1-xGaxSe2 and 15.8% for CdTe. The best recombination-state density Nt is in the range of 10-15-10-16 cm-3 acceptable for TPV applications. Higher efficiencies may be achieved because of the higher fluences, possibility of bandgap tailoring, and use of selective emitters such as rare earth oxides (erbia, holmia, yttria) and rare earth-yttrium aluminium garnets. As compared to higher bandgap semiconductors such as CdTe, it is easier to dope the lower bandgap semiconductors. TPV cell development can benefit from the more mature PV solar cell and opto

  18. Thin solid-lubricant films in space

    Science.gov (United States)

    Roberts, E. W.

    Low-friction films of thickness as low as 1 micron, created through sputter-deposition of low shear strength materials, are required in spacecraft applications requiring low power dissipation, such as cryogenic devices, and low torque noise, such as precision-pointing mechanisms. Due to their thinness, these coatings can be applied to high precision-machined tribological components without compromising their functional accuracy. Attention is here given to the cases of thin solid films for ball bearings, gears, and journal bearings.

  19. Laser-annealing of thin semiconductor films

    OpenAIRE

    Boneberg, Johannes; Nedelcu, Johann; Bucher, Ernst; Leiderer, Paul

    1994-01-01

    Optical reflectivity and transmissivity measurements have been used to investigate the dynamics of melting and recrystallisation of thin films of Si and Ge after laser-annealing with a ns Nd:YAG-laser pulse. We report on temperature dependent changes of the reflectivity of the liquid phase above and below the melting point and on various nucleation and solidification scenarios in thin film, depending on the energy density of the amding laser.

  20. Advances in CZTS thin films and nanostructured

    Science.gov (United States)

    Ali, N.; Ahmed, R.; Bakhtiar-Ul-Haq; Shaari, A.

    2015-06-01

    Already published data for the optical band gap (Eg) of thin films and nanostructured copper zinc tin sulphide (CZTS) have been reviewed and combined. The vacuum (physical) and non-vacuum (chemical) processes are focused in the study for band gap comparison. The results are accumulated for thin films and nanostructured in different tables. It is inferred from the re- view that the nanostructured material has plenty of worth by engineering the band gap for capturing the maximum photons from solar spectrum.

  1. Characteristics and durability of fluoropolymer thin films

    OpenAIRE

    Cheneler, David; Bowen, James; Evans, Stephen D.; Górzny, Marcin; Adams, Michael J; Ward, Michael C.L.

    2011-01-01

    The use of plasma-polymerised fluoropolymer (CFxOy) thin films in the manufacture of microelectromechanical systems (MEMS) devices is well-established, being employed in the passivation step of the deep reactive ion etching (DRIE) process, for example. This paper presents an investigation of the effect of exposure to organic and aqueous liquid media on plasma polymerised CFxOy thin films. Atomic force microscopy (AFM), scanning electron microscopy (SEM), ellipsometry, X-ray photoelectron spec...

  2. Microstructural evolution of tungsten oxide thin films

    Science.gov (United States)

    Hembram, K. P. S. S.; Thomas, Rajesh; Rao, G. Mohan

    2009-10-01

    Tungsten oxide thin films are of great interest due to their promising applications in various optoelectronic thin film devices. We have investigated the microstructural evolution of tungsten oxide thin films grown by DC magnetron sputtering on silicon substrate. The structural characterization and surface morphology were carried out using X-ray diffraction and Scanning Electron Microscopy (SEM). The as deposited films were amorphous, where as, the films annealed above 400 °C were crystalline. In order to explain the microstructural changes due to annealing, we have proposed a "instability wheel" model for the evolution of the microstructure. This model explains the transformation of mater into various geometries within them selves, followed by external perturbation.

  3. Microstructural evolution of tungsten oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hembram, K.P.S.S., E-mail: hembram@isu.iisc.ernet.in [Department of Instrumentation, Indian Institute of Science, Bangalore - 560 012 (India); Theoretical Science Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore - 560064 (India); Thomas, Rajesh; Rao, G. Mohan [Department of Instrumentation, Indian Institute of Science, Bangalore - 560 012 (India)

    2009-10-30

    Tungsten oxide thin films are of great interest due to their promising applications in various optoelectronic thin film devices. We have investigated the microstructural evolution of tungsten oxide thin films grown by DC magnetron sputtering on silicon substrate. The structural characterization and surface morphology were carried out using X-ray diffraction and Scanning Electron Microscopy (SEM). The as deposited films were amorphous, where as, the films annealed above 400 deg. were crystalline. In order to explain the microstructural changes due to annealing, we have proposed a 'instability wheel' model for the evolution of the microstructure. This model explains the transformation of mater into various geometries within them selves, followed by external perturbation.

  4. Effect of Ti seed and spacer layers on structure and magnetic properties of FeNi thin films and FeNi-based multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Svalov, A.V., E-mail: andrey.svalov@ehu.es [Departamento de Electricidad y Electrónica, Universidad del País Vasco (UPV/EHU), 48080 Bilbao (Spain); Department of Magnetism and Magnetic Nanomaterials, Ural Federal University, 620002 Ekaterinburg (Russian Federation); Larrañaga, A. [SGIker, Servicios Generales de Investigación, Universidad del País Vasco (UPV/EHU), 48080 Bilbao (Spain); Kurlyandskaya, G.V. [Departamento de Electricidad y Electrónica, Universidad del País Vasco (UPV/EHU), 48080 Bilbao (Spain); Department of Magnetism and Magnetic Nanomaterials, Ural Federal University, 620002 Ekaterinburg (Russian Federation)

    2014-10-15

    Highlights: • Fe{sub 19}Ni{sub 81} films and FeNi-based multilayers were prepared by magnetron sputtering. • The samples were deposited onto glass substrates at room temperature. • Ti/FeNi films exhibit good (1 1 1) texture and crystallinity. • The thick Cu seed increases the coercive force of the magnetic layer. • The thin Ti spacer restores the magnetic softness of the Cu/Ti/FeNi multilayers. - Abstract: The microstructure and magnetic properties of sputtered permalloy films and FeNi-based multilayers prepared by magnetron sputtering have been studied. X-ray diffraction measurements indicate that Ti/FeNi films exhibit good (1 1 1) texture and crystallinity. Ti/FeNi bilayers with high crystallographic quality have relatively low resistivity. The Ti seed layer does not influence the magnetic properties of FeNi film in Ti/FeNi bilayers, but the thick Cu seed layer leads to an increase of the coercive force of the magnetic layer. For the FeNi films deposited on thick Cu seed layer, the (0 1 0) and (0 0 2) diffraction peaks of hcp nickel were clearly observed. The thin Ti spacer between Cu and FeNi layers prevents the formation of the nickel phase and restores the magnetic softness of the FeNi layer in the Cu/Ti/FeNi sample. Obtained results can be important for the development of multilayer sensitive elements for giant magnetoimpedance or magnetoresistance detectors.

  5. Rechargeable lithium batteries based on Li{sub 1+x}V{sub 3}O{sub 8} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bonino, F. [Dept. of Chemistry, Rome Univ. `La Sapienza` (Italy); Panero, S. [Dept. ICMMPM, Rome Univ. `La Sapienza` (Italy); Pasquali, M. [Dept. ICMMPM, Rome Univ. `La Sapienza` (Italy); Pistoia, G. [Centro di Studio per l`Elettrochimica e la Chimica Fisica delle Interfasi, CNR, Rome (Italy)

    1995-08-01

    Low-temperature thin films of Li{sub 1+x}V{sub 3}O{sub 8} have been fabricated and tested in LiClO{sub 4}/propylene carbonate-1,2-dimethoxyethane/Li cells. These cells show very good intercalation kinetics, and at 0.4 C discharge rate produce a specific energy of {approx}110 Wh/kg. The films could be used in microbatteries for electronic devices, and applications requiring more power could also be envisaged. (orig.)

  6. Crystalline Indium Sulphide thin film by photo accelerated deposition technique

    Science.gov (United States)

    Dhanya, A. C.; Preetha, K. C.; Deepa, K.; Remadevi, T. L.

    2015-02-01

    Indium sulfide thin films deserve special attention because of its potential application as buffer layers in CIGS based solar cells. Highly transparent indium sulfide (InS) thin films were prepared using a novel method called photo accelerated chemical deposition (PCD). Ultraviolet source of 150 W was used to irradiate the solution. Compared to all other chemical methods, PCD scores its advantage for its low cost, flexible substrate and capable of large area of deposition. Reports on deposition of high quality InS thin films at room temperature are very rare in literature. The precursor solution was initially heated to 90°C for ten minutes and then deposition was carried out at room temperature for two hours. The appearance of the film changed from lemon yellow to bright yellow as the deposition time increased. The sample was characterized for its structural and optical properties. XRD profile showed the polycrystalline behavior of the film with mixed phases having crystallite size of 17 nm. The surface morphology of the films exhibited uniformly distributed honey comb like structures. The film appeared to be smooth and the value of extinction coefficient was negligible. Optical measurements showed that the film has more than 80% transmission in the visible region. The direct band gap energy was 2.47eV. This method is highly suitable for the synthesis of crystalline and transparent indium sulfide thin films and can be used for various photo voltaic applications.

  7. Loss mechanisms influence on Cu2ZnSnS4/CdS-based thin film solar cell performance

    Science.gov (United States)

    Courel, Maykel; Andrade-Arvizu, J. A.; Vigil-Galán, O.

    2015-09-01

    One of the most important issues in kesterite Cu2ZnSnS4 (CZTS)-based thin film solar cells is low open circuit voltage, which is mainly related to loss mechanisms that take place in both CZTS bulk material and CdS/CZTS interface. A device model for CZTS/CdS solar cell which takes into account loss mechanisms influence on solar cell performance is presented. The simulation results showed that our model is able to reproduce experimental observations reported for CZTS/CdS-based solar cells with the highest conversion efficiencies, measured under room temperature and AM1.5 intensity. The comparison of simulation results to experimental observations demonstrated that among the different loss mechanisms, trap-assisted tunneling losses are the major hurdle to boost open circuit voltage. Under this loss mechanism, a solar cell efficiency enhancement up to 10.2% with CdS donor concentration decrease was reached. Finally, the possible path toward a further solar cell efficiency improvement is discussed.

  8. Design of thin-film filters for resolution improvements in filter-array based spectrometers using DSP

    Science.gov (United States)

    Lee, Woong-Bi; Kim, Cheolsun; Ju, Gun Wu; Lee, Yong Tak; Lee, Heung-No

    2016-05-01

    Miniature spectrometers have been widely developed in various academic and industrial applications such as bio-medical, chemical and environmental engineering. As a family of spectrometers, optical filter-array based spectrometers fabricated using CMOS or Nano technology provide miniaturization, superior portability and cost effectiveness. In filterarray based spectrometers, the resolution which represents the ability how closely resolve two neighboring spectra, depends on the number of filters and the characteristics of the transmission functions (TFs) of the filters. In practice, due to the small-size and low-cost fabrication, the number of filters is limited and the shape of the TF of each filter is nonideal. As a development of modern digital signal processing (DSP), the spectrometers are equipped with DSP algorithms not only to alleviate distortions due to unexpected noise or interferences among filters but also reconstruct the original signal spectrum. For a high-resolution spectrum reconstruction by the DSP, the TFs of the filters need to be sufficiently uncorrelated with each other. In this paper, we present a design of optical thin-film filters which have the uncorrelated TFs. Each filter consists of multiple layers of high- and low-refractive index materials deposited on a substrate. The proposed design helps the DSP algorithm to improve resolution with a small number of filters. We demonstrate that a resolution of 5 nm within a range from 500 nm to 1100 nm can be achieved with only 64 filters.

  9. Detection of TATP precursor acetone at trace levels using rf sputtered SnO2 thin film-based sensors

    Science.gov (United States)

    Chowdhuri, Arijit; Sharma, Anjali; Gupta, Vinay

    2011-05-01

    Emerging threats of improvised explosive devices (IEDs) and homemade explosives (HMEs) have created a demand for reliable and unambiguous recognition of constituent analytes. Triacetone triperoxide (TATP), a cyclic peroxide based explosive has become a weapon of choice [1] in the hands of resourceful urban insurgents mainly because of ease of manufacture with readily available precursor constituents (acetone and concentrated hydrogen peroxide). Failure of conventional EDDs due to absence of nitrogen compounds coupled with the fact that TATP exhibits no significant absorption in UV region and does not demonstrate fluorescence has confined its detection to IR and Raman spectroscopy besides some enzyme-based tests and mass spectrometry [2]. Hence there is an urgent need for highly sensitive technique with a fast response speed that can detect presence of TATP at extremely low vapour pressure and purposely camouflaged physically or under cross-contamination with interfering compounds. In the present work trace level (20 ppm) acetone (precursor of TATP) sensing characteristics of rf sputtered semiconducting SnO2 thin films having embedded Pt interdigital electrodes have been investigated. Specifically a fast response speed of 08 seconds is noted and sensing characteristics of bare SnO2 and catalyst-SnO2 hetero-structures are compared. Innovative catalyst dispersal technique is shown to enhance sensor response as also reduce response times. Novel sensing hetero-structures with reversible acetone detection capabilities are shown to provide a feasible alternative for real-field operation along with remote detection with limited sample size.

  10. Ammonia gas-sensing characteristics of fluorescence-based poly(2-(acetoacetoxy)ethyl methacrylate) thin films.

    Science.gov (United States)

    He, Jing; Zhang, Tong-Yi; Chen, Guohua

    2012-05-01

    Novel fluorescent poly(2-(acetoacetoxy)ethyl methacrylate)(PAAEMA) latexes have been synthesized by miniemulsion polymerization employing a polymeric costabilizer. Nanoscale aggregates of macromolecules bearing β-dicarbonyl are formed in the prepared latex particles. Ammonia and the β-dicarbonyl aggregates assemble a supramolecular complex, which exhibits strong visible fluorescence under UV light. The formation of the complex is confirmed by the characteristic absorption peak located at about 275 nm in UV-Vis spectra. The absorption spectrum has been found to be applicable for ammonia detection. Atomic Force Microscopy (AFM) studies of surface morphology reveal that gas-sensing properties of the PAAEMA thin films involve the reversible absorption and desorption of ammonia. PAAEMA thin films are sensitive to ammonia gas and have a short response time of 80s when exposed to 54 ppm of ammonia gas concentration.

  11. Thin-film crystalline silicon solar cells

    CERN Document Server

    Brendel, Rolf

    2011-01-01

    This introduction to the physics of silicon solar cells focuses on thin cells, while reviewing and discussing the current status of the important technology. An analysis of the spectral quantum efficiency of thin solar cells is given as well as a full set of analytical models. This is the first comprehensive treatment of light trapping techniques for the enhancement of the optical absorption in thin silicon films.

  12. Fabrication of Meso-Porous Sintered Metal Thin Films by Selective Etching of Silica Based Sacrificial Template

    Directory of Open Access Journals (Sweden)

    Ludovic F. Dumee

    2014-08-01

    Full Text Available Meso-porous metal materials have enhanced surface energies offering unique surface properties with potential applications in chemical catalysis, molecular sensing and selective separation. In this paper, commercial 20 nm diameter metal nano-particles, including silver and copper were blended with 7 nm silica nano-particles by shear mixing. The resulted powders were cold-sintered to form dense, hybrid thin films. The sacrificial silica template was then removed by selective etching in 12 wt% hydrofluoric acid solutions for 15 min to reveal a purely metallic meso-porous thin film material. The impact of the initial silica nano-particle diameter (7–20 nm as well as the sintering pressure (5–20 ton·m−2 and etching conditions on the morphology and properties of the final nano-porous thin films were investigated by porometry, pyknometery, gas and liquid permeation and electron microscopy. Furthermore, the morphology of the pores and particle aggregation during shear mixing were assessed through cross-sectioning by focus ion beam milling. It is demonstrated that meso-pores ranging between 50 and 320 nm in average diameter and porosities up to 47% can be successfully formed for the range of materials tested.

  13. Expandable and retractable self-rolled structures based on metal/polymer thin film for flow sensing

    Science.gov (United States)

    Zhu, Jianzhong; White, Carl; Saadat, Mehdi; Bart-Smith, Hilary

    2015-11-01

    Most aquatic animals such as fish rely heavily on their ability of detect and respond to ambient flows in order to explore and inhabit various habitats or survive predator-prey encounters. Fish utilize neuromasts in their skin surface and lateral lines in their bodies to align themselves while swimming upstream for migration, avoid obstacles, reduce locomotion cost, and detect flow variations caused by potential predators. In this study, a thin film MEMS sensor analogous to a fish neuromast has been designed for flow sensing. Residual stress arises in many thin film materials during processing. Metal and polymer thin film materials with a significant difference in elastic modular were chosen to form a multiple-layer structure. Upon releasing, the structure rolls into a tube due to mechanical property mismatch. The self-rolled tube can expand or retract, depending on the existence of external force such as flow. An embedded strain sensor detects the deformation of the tube and hence senses the ambient flow. Numerical simulations were conducted to optimize the structural design. Experiments were performed in a flow tank to quantify the performance of the sensor. This research is supported by the Office of Naval Research under the MURI Grant N00014-14-1-0533.

  14. Thin-film-based scintillators for hard x-ray microimaging detectors: the ScinTAX Project

    Science.gov (United States)

    Rack, A.; Cecilia, A.; Douissard, P.-A.; Dupré, K.; Wesemann, V.; Baumbach, T.; Couchaud, M.; Rochet, X.; Riesemeier, H.; Radtke, M.; Martin, T.

    2014-09-01

    The project ScinTAX developed novel thin scintillating films for the application in high performance X-ray imaging and subsequent introduced new X-ray detectors to the market. To achieve this aim lutetium orthosilicate (LSO) scintillators doped with different activators were grown successfully by liquid phase epitaxy. The high density of LSO (7.4 g/cm3), the effective atomic number (65.2) and the high light yield make this scintillator highly applicable for indirect X-ray detection in which the ionizing radiation is converted into visible light and then registered by a digital detector. A modular indirect detection system has been developed to fully exploit the potential of this thin film scintillator for radiographic and tomographic imaging. The system is compatible for high-resolution imaging with moderate dose as well as adaptable to intense high-dose applications where radiation hard microimaging detectors are required. This proceedings article shall review the achieved performances and technical details on this high-resolution detector system which is now available. A selected example application demonstrates the great potential of the optimized detector system for hard X-ray microimaging, i.e. either to improve image contrast due to the availability of efficient thin crystal films or to reduce the dose to the sample.

  15. An In-situ Real-Time Optical Fiber Sensor Based on Surface Plasmon Resonance for Monitoring the Growth of TiO2 Thin Films

    Science.gov (United States)

    Tsao, Yu-Chia; Tsai, Woo-Hu; Shih, Wen-Ching; Wu, Mu-Shiang

    2013-01-01

    An optical fiber sensor based on surface plasmon resonance (SPR) is proposed for monitoring the thickness of deposited nano-thin films. A side-polished multimode SPR optical fiber sensor with an 850 nm-LD is used as the transducing element for real-time monitoring of the deposited TiO2 thin films. The SPR optical fiber sensor was installed in the TiO2 sputtering system in order to measure the thickness of the deposited sample during TiO2 deposition. The SPR response declined in real-time in relation to the growth of the thickness of the TiO2 thin film. Our results show the same trend of the SPR response in real-time and in spectra taken before and after deposition. The SPR transmitted intensity changes by approximately 18.76% corresponding to 50 nm of deposited TiO2 thin film. We have shown that optical fiber sensors utilizing SPR have the potential for real-time monitoring of the SPR technology of nanometer film thickness. The compact size of the SPR fiber sensor enables it to be positioned inside the deposition chamber, and it could thus measure the film thickness directly in real-time. This technology also has potential application for monitoring the deposition of other materials. Moreover, in-situ real-time SPR optical fiber sensor technology is in inexpensive, disposable technique that has anti-interference properties, and the potential to enable on-line monitoring and monitoring of organic coatings. PMID:23881144

  16. Preparation and thermo-optical characteristics of a smart polymer-stabilized liquid crystal thin film based on smectic A–chiral nematic phase transition

    International Nuclear Information System (INIS)

    A smart polymer stabilized liquid crystal (PSLC) thin film with temperature-controllable light transmittance was prepared based on a smectic-A (SmA)–chiral nematic (N*) phase transition, and then the effect of the composition and the preparation condition of the PSLC film on its thermo-optical (T-O) characteristics has been investigated in detail. Within the temperature range of the SmA phase, the PSLC shows a strong opaque state due to the focal conic alignment of liquid crystal (LC) molecules, while the film exhibits a transparent state result from the parallel alignment of N* phase LC molecules at a higher temperature. Importantly, the PSLC films with different temperature of phase transition and contrast ratio can be prepared by changing the composition of photo-polymerizable monomer/LC/chiral dopant. According to the competition between the polymerization of the curable monomers and the diffusion of LC molecules, the ultraviolet (UV) curing surrounding temperature and the intensity of UV irradiation play a critical role in tuning the size of the polymer network meshes, which in turn influence the contrast ratio and the switching speed of the film. Our observations are expected to pave the way for preparing smart PSLC thin films for applications in areas of smart windows, thermo-detectors and other information recording devices. (paper)

  17. Low voltage operated, sol–gel derived oxide thin film transistor based on high-k Gd2O3 gate dielectric

    International Nuclear Information System (INIS)

    Low power-driven oxide thin film transistor (TFT) with a high-k gate dielectric is fabricated by a simple solution process. Sol–gel derived Gd2O3 film exhibits the dielectric constant in the range of 9–14 with breakdown field as high as 3.5 MV cm−1. Zn–In–Sn–O based TFTs combined with a corresponding film demonstrate the readiness of solution processed high-k film as gate insulators. The resultant device exhibits the enhanced performance with the field-effect mobility of ∼1.9 cm2 V−1 s−1, which is improved by a factor of 4.5 comparing with the conventional TFT based on a SiO2 insulator, and the exceptionally low operating voltage of 6 V. - Highlights: ► Solution processed high-k Gd2O3 gate insulator for oxide thin film transistors (TFTs). ► Low voltage-operated TFTs with enhanced switching property can be obtained. ► Applicable to the promising electronic materials for printing-based TFTs

  18. Post deposition purification of PTCDA thin films

    International Nuclear Information System (INIS)

    The decomposition of perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) molecules during evaporation of unpurified raw material in ultra high vacuum was studied. The fragments were identified by mass spectrometry and the influence of these fragments and further contaminations of the raw material on the electronic structure of PTCDA thin films was measured by photoemission spectroscopy. Annealing of contaminated PTCDA films was tested as cheap and easy to perform method for (partial) post deposition purification of the contaminated films

  19. Microcrystalline organic thin-film solar cells.

    Science.gov (United States)

    Verreet, Bregt; Heremans, Paul; Stesmans, Andre; Rand, Barry P

    2013-10-11

    Microcrystalline organic films with tunable thickness are produced directly on an indium-tin-oxide substrate, by crystallizing a thin amorphous rubrene film followed by its use as a template for subsequent homoepitaxial growth. These films, with exciton diffusion lengths exceeding 200 nm, produce solar cells with increasing photocurrents at thicknesses up to 400 nm with a fill factor >65%, demonstrating significant potential for microcrystalline organic electronic devices. PMID:23939936

  20. Impedimetric and amperometric bifunctional glucose biosensor based on hybrid organic-inorganic thin films.

    Science.gov (United States)

    Wang, Huihui; Ohnuki, Hitoshi; Endo, Hideaki; Izumi, Mitsuru

    2015-02-01

    A novel glucose biosensor with an immobilized mediator was studied using electrochemical impedance spectroscopy (EIS) and amperometry measurements. The biosensor has a characteristic ultrathin form and is composed of a self-assembled monolayer anchoring glucose oxidase (GOx) covered with Langmuir-Blodgett (LB) films of Prussian blue (PB). The immobilized PB in the LB films acts as a mediator and enables the biosensor to work under a low potential (0.0V vs. Ag/AgCl). In the EIS measurements, a dramatic decrease in charge transfer resistance (Rct) was observed with sequential addition of glucose, which can be attributed to enzymatic activity. The linearity of the biosensor response was observed by the variation of the sensor response (1/Rct) as a function of glucose concentration in the range 0 to 25mM. The sensor also showed linear amperometric response below 130mM glucose. The organic-inorganic system of GOx and PB nanoclusters demonstrated bifunctional sensing action, both amperometry and EIS modes, as well as long sensing stability for 4 days. PMID:25014167