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Sample records for bifeo3 thin films

  1. Photoconductivity in BiFeO3 thin films

    Science.gov (United States)

    Basu, S. R.; Martin, L. W.; Chu, Y. H.; Gajek, M.; Ramesh, R.; Rai, R. C.; Xu, X.; Musfeldt, J. L.

    2008-03-01

    The optical properties of epitaxial BiFeO3 thin films have been characterized in the visible range. Variable temperature spectra show an absorption onset near 2.17eV, a direct gap (2.667±0.005eV at 300K), and charge transfer excitations at higher energy. Additionally, we report photoconductivity in BiFeO3 films under illumination from a 100mW /cm2 white light source. A direct correlation is observed between the magnitude of the photoconductivity and postgrowth cooling pressure. Dark conductivities increased by an order of magnitude when comparing films cooled in 760 and 0.1Torr. Large increases in photoconductivity are observed in light.

  2. BiFeO3 thin films: Novel effects

    Indian Academy of Sciences (India)

    photolithography followed by etching of the silver film. Saturation ... Fe in +3 state. Films thus obtained are therefore highly resistive (ρ ∼ 108–109 cm) and hence exhibit saturated ferroelectric hysteresis loop (figure 3). Anomaly in ... BiFeO3 bulk sample by Rogniskaya et al [4] had indicated abrupt change in lattice parame-.

  3. Structural and optical properties of cobalt doped multiferroics BiFeO3 nanostructure thin films

    Science.gov (United States)

    Prasannakumara, R.; Naik, K. Gopalakrishna

    2018-05-01

    Bismuth ferrite (BiFeO3) and Cobalt doped BiFeO3 (BiFe1-XCoXO3) nanostructure thin films were deposited on glass substrates by the sol-gel spin coating method. The X-ray diffraction patterns (XRD) of the grown BiFeO3 and BiFe1-XCoXO3 nanostructure thin films showed distorted rhombohedral structure. The shifting of peaks to higher angles was observed in cobalt doped BiFeO3. The surface morphology of the BiFeO3 and BiFe1-XCoXO3 nanostructure thin films were studied using FESEM, an increase in grain size was observed as Co concentration increases. The thickness of the nanostructure thin films was examined using FESEM cross-section. The EDX studies confirmed the elemental composition of the grown BiFeO3 and BiFe1-XCoXO3 nanostructure thin films. The optical characterizations of the grown nanostructure thin films were carried out using FTIR, it confirms the existence of Fe-O and Bi-O bands and UV-Visible spectroscopy shows the increase in optical band gap of the BiFeO3 nanostructure thin films with Co doping by ploting Tauc plot.

  4. Nanoscale Control of Exchange Bias with BiFeO3 Thin Films

    NARCIS (Netherlands)

    Martin, Lane W.; Chu, Ying-Hao; Holcomb, Mikel B.; Huijben, Mark; Yu, Pu; Han, Shu-Jen; Lee, Donkoun; Wang, Shan X.; Ramesh, R.

    2008-01-01

    We demonstrate a direct correlation between the domain structure of multiferroic BiFeO3 thin films and exchange bias of Co0.9Fe0.1/BiFeO3 heterostructures. Two distinct types of interactions − an enhancement of the coercive field (exchange enhancement) and an enhancement of the coercive field

  5. Polarization-tuned diode behaviour in multiferroic BiFeO3 thin films

    KAUST Repository

    Yao, Yingbang; Zhang, Bei; Chen, Long; Yang, Yang; Wang, Zhihong; Alshareef, Husam N.; Zhang, Xixiang

    2012-01-01

    Asymmetric rectifying I-V behaviour of multiferroic BiFeO3 (BFO) thin films grown on transparent ITO-coated glass was quantitatively studied as a function of ferroelectric polarization. Different polarized states were established by unipolar

  6. Photoelectrochemical Performance Observed in Mn-Doped BiFeO3 Heterostructured Thin Films

    Directory of Open Access Journals (Sweden)

    Hao-Min Xu

    2016-11-01

    Full Text Available Pure BiFeO3 and heterostructured BiFeO3/BiFe0.95Mn0.05O3 (5% Mn-doped BiFeO3 thin films have been prepared by a chemical deposition method. The band structures and photosensitive properties of these films have been investigated elaborately. Pure BiFeO3 films showed stable and strong response to photo illumination (open circuit potential kept −0.18 V, short circuit photocurrent density was −0.023 mA·cm−2. By Mn doping, the energy band positions shifted, resulting in a smaller band gap of BiFe0.95Mn0.05O3 layer and an internal field being built in the BiFeO3/BiFe0.95Mn0.05O3 interface. BiFeO3/BiFe0.95Mn0.05O3 and BiFe0.95Mn0.05O3 thin films demonstrated poor photo activity compared with pure BiFeO3 films, which can be explained by the fact that Mn doping brought in a large amount of defects in the BiFe0.95Mn0.05O3 layers, causing higher carrier combination and correspondingly suppressing the photo response, and this negative influence was more considerable than the positive effects provided by the band modulation.

  7. BiFeO3 epitaxial thin films and devices: past, present and future

    Science.gov (United States)

    Sando, D.; Barthélémy, A.; Bibes, M.

    2014-11-01

    The celebrated renaissance of the multiferroics family over the past ten years has also been that of its most paradigmatic member, bismuth ferrite (BiFeO3). Known since the 1960s to be a high temperature antiferromagnet and since the 1970s to be ferroelectric, BiFeO3 only had its bulk ferroic properties clarified in the mid-2000s. It is however the fabrication of BiFeO3 thin films and their integration into epitaxial oxide heterostructures that have fully revealed its extraordinarily broad palette of functionalities. Here we review the first decade of research on BiFeO3 films, restricting ourselves to epitaxial structures. We discuss how thickness and epitaxial strain influence not only the unit cell parameters, but also the crystal structure, illustrated for instance by the discovery of the so-called T-like phase of BiFeO3. We then present its ferroelectric and piezoelectric properties and their evolution near morphotropic phase boundaries. Magnetic properties and their modification by thickness and strain effects, as well as optical parameters, are covered. Finally, we highlight various types of devices based on BiFeO3 in electronics, spintronics, and optics, and provide perspectives for the development of further multifunctional devices for information technology and energy harvesting.

  8. Magnetoelectric coupling effect in transition metal modified polycrystalline BiFeO3 thin films

    International Nuclear Information System (INIS)

    Sreenivas Puli, Venkata; Kumar Pradhan, Dhiren; Gollapudi, Sreenivasulu; Coondoo, Indrani; Panwar, Neeraj; Adireddy, Shiva; Chrisey, Douglas B.; Katiyar, Ram S.

    2014-01-01

    Rare-earth (Sm) and transition metal (Co) modified polycrystalline BiFeO 3 (BFO) thin films have been deposited on Pt/TiO 2 /SiO 2 /Si substrate successfully through pulsed laser deposition (PLD) technique. Piezoelectric, leakage current and temperature dependent dielectric and magnetic behaviour were investigated for the films. Typical “butterfly-shaped” loop were observed in BSFCO films with an effective piezoelectric constant (d 33 ) ∼94 pm/V at 0.6 MV/cm. High dielectric constant ∼900 and low dielectric loss ∼0.25 were observed at room temperature. M–H loops have shown relatively high saturation magnetization ∼35 emu/cm 3 at a maximum field of H ∼20 kOe. Enhanced magnetoelectric coupling response is observed under applied magnetic field. The multiferroic, piezoelectric, leakage current behaviours were explored. Such studies should be helpful in designing multiferroic materials based on BSFCO films. - Highlights: • Transition metal modified polycrystalline BiFeO 3 thin films prepared using PLD. • High ME-coupling response was observed in co-substituted BiFeO 3 thin films. • High magnetization ∼35 emu/cm 3 at a maximum field of H ∼20 kOe. • Low leakage current might be due to co-substitution in BiFeO 3 thin films. • A notable piezoelectric constant d 33 ∼94 pm/V was found in BiFeO 3 thin films

  9. Optimization of excess Bi doping to enhance ferroic orders of spin casted BiFeO3 thin film

    International Nuclear Information System (INIS)

    Gupta, Surbhi; Gupta, Vinay; Tomar, Monika; James, A. R.; Pal, Madhuparna; Guo, Ruyan; Bhalla, Amar

    2014-01-01

    Multiferroic Bismuth Ferrite (BiFeO 3 ) thin films with varying excess bismuth (Bi) concentration were grown by chemical solution deposition technique. Room temperature multiferroic properties (ferromagnetism, ferroelectricity, and piezoelectricity) of the deposited BiFeO 3 thin films have been studied. High resolution X-ray diffraction and Raman spectroscopy studies reveal that the dominant phases formed in the prepared samples change continuously from a mixture of BiFeO 3 and Fe 2 O 3 to pure BiFeO 3 phase and, subsequently, to a mixture of BiFeO 3 and Bi 2 O 3 with increase in the concentration of excess Bi from 0% to 15%. BiFeO 3 thin films having low content (0% and 2%) of excess Bi showed the traces of ferromagnetic phase (γ-Fe 2 O 3 ). Deterioration in ferroic properties of BiFeO 3 thin films is also observed when prepared with higher content (15%) of excess Bi. Single-phased BiFeO 3 thin film prepared with 5% excess Bi concentration exhibited the soft ferromagnetic hysteresis loops and ferroelectric characteristics with remnant polarization 4.2 μC/cm 2 and saturation magnetization 11.66 emu/g. The switching of fine spontaneous domains with applied dc bias has been observed using piezoresponse force microscopy in BiFeO 3 thin films having 5% excess Bi. The results are important to identify optimum excess Bi concentration needed for the formation of single phase BiFeO 3 thin films exhibiting the improved multiferroic properties.

  10. Magneto-optical properties of BiFeO3 thin films using surface plasmon resonance technique

    International Nuclear Information System (INIS)

    Paliwal, Ayushi; Sharma, Anjali; Tomar, Monika; Gupta, Vinay

    2014-01-01

    Indigeneously assembled surface plasmon resonance (SPR) set up has been exploited to study the magnetic field dependent optical properties of BiFeO 3 thin films. BiFeO 3 thin films have been deposited onto gold (Au) coated glass prism by using pulsed laser deposition technique. The surface plasmon modes in prism/Au/BiFeO 3 /air structure have been excited in Kretschmann configuration at the interface of Au/BiFeO 3 thin films. The SPR reflectance curves obtained for prism/Au/BiFeO 3 /air structure were utilized to investigate the optical properties of BiFeO 3 thin films at optical frequency (λ=633 nm) as a function of applied magnetic field. SPR curves shows a continuous shift towards lower angles with increasing applied magnetic field, which indicate the promising application of ferromagnetic BiFeO 3 film as a magnetic field sensor. Complex dielectric constant of deposited BiFeO 3 film was determined by fitting the experimental SPR data with Fresnel's equations. The variation of complex dielectric constant and refractive index of BiFeO 3 film was studied with increase in magnetic field, and the sensitivity of magnetic field sensor was found to be about 0.52 RIU/T

  11. Photovoltaic effect in transition metal modified polycrystalline BiFeO3 thin films

    International Nuclear Information System (INIS)

    Puli, Venkata Sreenivas; Chrisey, Douglas B; Pradhan, Dhiren Kumar; Katiyar, Rajesh Kumar; Misra, Pankaj; Scott, J F; Katiyar, Ram S; Coondoo, Indrani; Panwar, Neeraj

    2014-01-01

    We report photovoltaic (PV) effect in multiferroic Bi 0.9 Sm 0.1 Fe 0.95 Co 0.05 O 3 (BSFCO) thin films. Transition metal modified polycrystalline BiFeO 3 (BFO) thin films have been deposited on Pt/TiO 2 /SiO 2 /Si substrate successfully through pulsed laser deposition (PLD). PV response is observed under illumination both in sandwich and lateral electrode configurations. The open-circuit voltage (V oc ) and the short-circuit current density (J sc ) of the films in sandwich electrode configuration under illumination are measured to be 0.9 V and −0.051 µA cm −2 . Additionally, we report piezoresponse for BSFCO films, which confirms ferroelectric piezoelectric behaviour. (paper)

  12. Understanding Strain-Induced Phase Transformations in BiFeO3 Thin Films.

    Science.gov (United States)

    Dixit, Hemant; Beekman, Christianne; Schlepütz, Christian M; Siemons, Wolter; Yang, Yongsoo; Senabulya, Nancy; Clarke, Roy; Chi, Miaofang; Christen, Hans M; Cooper, Valentino R

    2015-08-01

    Experiments demonstrate that under large epitaxial strain a coexisting striped phase emerges in BiFeO 3 thin films, which comprises a tetragonal-like ( T ') and an intermediate S ' polymorph. It exhibits a relatively large piezoelectric response when switching between the coexisting phase and a uniform T ' phase. This strain-induced phase transformation is investigated through a synergistic combination of first-principles theory and experiments. The results show that the S ' phase is energetically very close to the T ' phase, but is structurally similar to the bulk rhombohedral ( R ) phase. By fully characterizing the intermediate S ' polymorph, it is demonstrated that the flat energy landscape resulting in the absence of an energy barrier between the T ' and S ' phases fosters the above-mentioned reversible phase transformation. This ability to readily transform between the S ' and T ' polymorphs, which have very different octahedral rotation patterns and c / a ratios, is crucial to the enhanced piezoelectricity in strained BiFeO 3 films. Additionally, a blueshift in the band gap when moving from R to S ' to T ' is observed. These results emphasize the importance of strain engineering for tuning electromechanical responses or, creating unique energy harvesting photonic structures, in oxide thin film architectures.

  13. Giant Polarization Rotation in BiFeO3/SrTiO3 Thin Films.

    Science.gov (United States)

    Langner, M. C.; Chu, Y. H.; Martin, L. M.; Gajek, M.; Ramesh, R.; Orenstein, J.

    2008-03-01

    We use optical second harmonic generation to probe dynamics of the ferroelectric polarization in (111) oriented BiFeO3 thin films grown on SrTiO3 substrates. The second harmonic response indicates 3m point group symmetry and is consistent with a spontaneous polarization normal to the surface of the film. We measure large changes in amplitude and lowering of symmetry, consistent with polarization rotation, when modest electric fields are applied in the plane of the film. At room temperature the rotation is an order of magnitude larger than expected from reported values of the dielectric constant and increases further (as 1/T) as temperature is lowered. We propose a substrate interaction model to explain these results.

  14. Polarization-tuned diode behaviour in multiferroic BiFeO3 thin films

    KAUST Repository

    Yao, Yingbang

    2012-12-28

    Asymmetric rectifying I-V behaviour of multiferroic BiFeO3 (BFO) thin films grown on transparent ITO-coated glass was quantitatively studied as a function of ferroelectric polarization. Different polarized states were established by unipolar or bipolar poling with various applied electric fields. The effects of polarization relaxation and fatigue on the currents were also investigated. We found that the conduction currents and the associated rectifications were controlled by the amplitude and direction of the polarization. We clearly observed the linear dependence of the current on the polarization. It is suggested that the space-charge-limited conduction and the charge injection at the Schottky interface between the film and the electrodes dominate the current. The electrically controlled rectifying behaviour observed in this study may be useful in nonvolatile resistance memory devices or tunable diodes. © 2013 IOP Publishing Ltd.

  15. Local conductivity and the role of vacancies around twin walls of (001)-BiFeO3 thin films

    NARCIS (Netherlands)

    Farokhipoor, S.; Noheda, Beatriz

    2012-01-01

    BiFeO3 thin films epitaxially grown on SrRuO3-buffered (001)-oriented SrTiO3 substrates show orthogonal bundles of twin domains, each of which contains parallel and periodic 71 degrees domain walls. A smaller amount of 109 degrees domain walls are also present at the boundaries between two adjacent

  16. Bulk photovoltaic effect in epitaxial (K, Nb) substituted BiFeO3 thin films

    Science.gov (United States)

    Agarwal, Radhe; Zheng, Fan; Sharma, Yogesh; Hong, Seungbum; Rappe, Andrew; Katiyar, Ram

    We studied the bulk photovoltaic effect in epitaxial (K, Nb) modified BiFeO3 (BKFNO) thin films using theoretical and experimental methods. Epitaxial BKFNO thin films were grown by pulsed laser deposition (PLD). First, we have performed first principles density function theory (DFT) using DFT +U method to calculate electronic band structure, including Hubbard-Ueff (Ueff =U-J) correction into Hamiltonian. The electronic band structure calculations showed a direct band gap at 1.9 eV and a defect level at 1.7 eV (in a 40 atom BKFNO supercell), sufficiently lower in comparison to the experimentally observed values. Furthermore, the piezoforce microscopy (PFM) measurements indicated the presence of striped polydomains in BKFNO thin films. Angle-resolved PFM measurements were also performed to find domain orientation and net polarization directions in these films. The experimental studies of photovoltaic effect in BKNFO films showed a short circuit current of 59 micro amp/cm2 and open circuit voltage of 0.78 V. We compared our experimental results with first principles shift current theory calculations of bulk photovoltaic effect (BPVE).The synergy between theory and experimental results provided a realization of significant role of BPVE in order to understand the photovoltaic mechanism in ferroelectrics.

  17. Enhanced magnetic properties of chemical solution deposited BiFeO3 thin film with ZnO buffer layer

    International Nuclear Information System (INIS)

    Rajalakshmi, R.; Kambhala, Nagaiah; Angappane, S.

    2012-01-01

    Highlights: ► Enhanced magnetization of BiFeO 3 is important for strong magnetoelectric coupling. ► BiFeO 3 film with ZnO buffer layer was successfully synthesized by chemical method. ► Magnetization of BiFeO 3 has increased by more than 10 times with ZnO buffer layer. ► A mechanism for enhancement in ferromagnetism of BiFeO 3 film is proposed. - Abstract: Magnetic properties of BiFeO 3 films deposited on Si substrates with and without ZnO buffer layer have been studied in this work. We adopted the chemical solution deposition method for the deposition of BiFeO 3 as well as ZnO films. The x-ray diffraction measurements on the deposited films confirm the formation of crystalline phase of BiFeO 3 and ZnO films, while our electron microscopy measurements help to understand the morphology of few micrometers thick films. It is found that the deposited ZnO film exhibit a hexagonal particulate surface morphology, whereas BiFeO 3 film fully covers the ZnO surface. Our magnetic measurements reveal that the magnetization of BiFeO 3 has increased by more than ten times in BiFeO 3 /ZnO/Si film compared to BiFeO 3 /Si film, indicating the major role played by ZnO buffer layer in enhancing the magnetic properties of BiFeO 3 , a technologically important multiferroic material.

  18. Interfacial effects on the electrical properties of multiferroic BiFeO3/Pt/Si thin film heterostructures

    International Nuclear Information System (INIS)

    Yakovlev, S.; Zekonyte, J.; Solterbeck, C.-H.; Es-Souni, M.

    2005-01-01

    Polycrystalline BiFeO 3 thin films of various thickness were fabricated on (111)Pt/Ti/SiO 2 /Si substrates via chemical solution deposition. The electrical properties were investigated using impedance and leakage current measurements. X-ray photoelectron spectroscopy (XPS) combined with Ar ion milling (depth profiling) was used to investigate elemental distribution near the electrode-film interface. It is shown that the dielectric constant depends on film thickness due to the presence of an interfacial film-electrode layer evidenced by XPS investigation. Direct current conductivity is found to be governed by Schottky and/or Poole-Frenkel mechanisms

  19. Orthorhombic polar Nd-doped BiFeO3 thin film on MgO substrate

    International Nuclear Information System (INIS)

    Leontyev, I N; Janolin, P-E; Dkhil, B; Yuzyuk, Yu I; El-Marssi, M; Chernyshov, D; Dmitriev, V; Golovko, Yu I; Mukhortov, V M

    2011-01-01

    A Nd-doped BiFeO 3 thin film deposited on MgO substrate was studied by synchrotron diffraction. The ferroelectric nature of the film is proven by in-plane remanent polarization measurement. The highest possible symmetry of the film is determined to be orthorhombic, within the Fm2m space group. Such a structure is rotated by 45 0 with respect to the substrate and is consistent with tilts of oxygen octahedra doubling the unit cell. This polar structure presents a rather unusual strain-accommodation mechanism. (fast track communication)

  20. Thickness-dependent piezoelectric behaviour and dielectric properties of lanthanum modified BiFeO3 thin films

    Directory of Open Access Journals (Sweden)

    Glenda Biasotto

    2011-03-01

    Full Text Available Bi0.85La0.15FeO3 (BLFO thin films were deposited on Pt(111/Ti/SiO2 /Si substrates by the soft chemical method. Films with thicknesses ranging from 140 to 280 nm were grown on platinum coated silicon substrates at 500°C for 2 hours. The X-ray diffraction analysis of BLFO films evidenced a hexagonal structure over the entire thickness range investigated. The grain size of the film changes as the number of the layers increases, indicating thickness dependence. It is found that the piezoelectric response is strongly influenced by the film thickness. It is shown that the properties of BiFeO3 thin films, such as lattice parameter, dielectric permittivity, piezoeletric coefficient etc., are functions of misfit strains.

  1. Ferroelectricity down to at least 2 nm in multiferroic BiFeO3 epitaxial thin films

    International Nuclear Information System (INIS)

    Bea, H.; Fusil, S.; Bouzehouane, K.; Sirena, M.; Herranz, G.; Jacquet, E.; Contour, J.-P.; Barthelemy, A.; Bibes, M.

    2006-01-01

    We report here on the preservation of ferroelectricity down to 2 nm in BiFeO 3 ultrathin films. The electric polarization can be switched reversibly and is stable over several days. Our findings insight on the fundamental problem of ferroelectricity at low thickness and confirm the potential of BiFeO 3 as a lead-free ferroelectric and multiferroic material for nanoscale devices. (author)

  2. Multiferroic BiFeO3 thin films and nanodots grown on highly oriented pyrolytic graphite substrates

    Science.gov (United States)

    Shin, Hyun Wook; Son, Jong Yeog

    2017-12-01

    Multiferroic BiFeO3 (BFO) thin films and nanodots are deposited on highly oriented pyrolytic graphite (HOPG) substrates via a pulsed laser deposition technique, where the HOPG surface has a honeycomb lattice structure made of carbon atoms, similar to graphene. A graphene/BFO/HOPG capacitor exhibited multiferroic properties, namely ferroelectricity (a residual polarization of 26.8 μC/cm2) and ferromagnetism (a residual magnetization of 1.1 × 10-5 emu). The BFO thin film had high domain wall energies and demonstrated switching time of approximately 82 ns. An 8-nm BFO nanodot showed a typical piezoelectric hysteresis loop with an effective residual piezoelectric constant of approximately 110 pm/V and exhibited two clearly separated current curves depending on the ferroelectric polarization direction.

  3. Domain wall magnetoresistance in BiFeO3 thin films measured by scanning probe microscopy

    NARCIS (Netherlands)

    Domingo, N.; Farokhipoor, S.; Santiso, J.; Noheda, B.; Catalan, G.

    2017-01-01

    We measure the magnetotransport properties of individual 71 degrees domain walls in multiferroic BiFeO3 by means of conductive-atomic force microscopy (C-AFM) in the presence of magnetic fields up to one Tesla. The results suggest anisotropic magnetoresistance at room temperature, with the sign of

  4. Annealing effect on the bipolar resistive switching behaviors of BiFeO3 thin films on LaNiO3-buffered Si substrates

    International Nuclear Information System (INIS)

    Chen Xinman; Zhang Hu; Ruan Kaibin; Shi Wangzhou

    2012-01-01

    Highlights: ► Annealing effect on the bipolar resistive switching behaviors of BiFeO 3 thin films with Pt/BiFeO 3 /LNO was reported. ► Rectification property was explained from the asymmetrical contact between top and bottom interfaces and the distinct oxygen vacancy density. ► The modification of Schottky-like barrier was suggested to be responsible for the resistance switching behaviors of Pt/BiFeO 3 /LNO devices. - Abstract: We reported the annealing effect on the electrical behaviors of BiFeO 3 thin films integrated on LaNiO 3 (LNO) layers buffered Si substrates by sol–gel spin-coating technique. All the BiFeO 3 thin films exhibit the reversible bipolar resistive switching behaviors with Pt/BiFeO 3 /LNO configuration. The electrical conduction mechanism of the devices was dominated by the Ohmic conduction in the low resistance state and trap-controlled space charged limited current in the high resistance state. Good diode-like rectification property was observed in device with BiFeO 3 film annealed at 500 °C, but vanished in device with BiFeO 3 film annealed at 600 °C. This was attributed to the asymmetrical contact between top and bottom interfaces as well as the distinct oxygen vacancy density verified by XPS. Furthermore, the modification of Schottky-like barrier due to the drift of oxygen vacancies was suggested to be responsible for the resistance switching behaviors of Pt/BiFeO 3 /LNO devices.

  5. Domain wall magnetoresistance in BiFeO3 thin films measured by scanning probe microscopy.

    Science.gov (United States)

    Domingo, N; Farokhipoor, S; Santiso, J; Noheda, B; Catalan, G

    2017-08-23

    We measure the magnetotransport properties of individual 71° domain walls in multiferroic BiFeO 3 by means of conductive-atomic force microscopy (C-AFM) in the presence of magnetic fields up to one Tesla. The results suggest anisotropic magnetoresistance at room temperature, with the sign of the magnetoresistance depending on the relative orientation between the magnetic field and the domain wall plane. A consequence of this finding is that macroscopically averaged magnetoresistance measurements for domain wall bunches are likely to underestimate the magnetoresistance of each individual domain wall.

  6. Multiferroic properties of BiFeO3/BaTiO3 multilayered thin films

    International Nuclear Information System (INIS)

    Sharma, Savita; Tomar, Monika; Kumar, Ashok; Puri, Nitin K.; Gupta, Vinay

    2014-01-01

    Multilayered structures of multiferroic BiFeO 3 (BFO) and ferroelectric BaTiO 3 (BTO) have been fabricated using pulsed laser deposition (PLD). Ferromagnetic and ferroelectric properties of the multilayered system (BFO/BTO) have been investigated. It could be inferred that the magnetization increases with the incorporation of BTO buffer layer, which indicates a coupling between the ferroelectric and ferromagnetic orders. Vibrating sample magnetometer (VSM) measurements performed on the prepared multiferroic samples show that the magnetization is significantly increased (M s =56.88 emu/cm 3 ) for the multilayer system with more number of layers (four) keeping the total thickness of the multilayered system constant (350 nm) meanwhile maintaining the sufficiently enhanced ferroelectric properties (P r =29.68 µC/cm 2 )

  7. Synthesis of BiFeO3 thin films on single-terminated Nb : SrTiO3 (111 substrates by intermittent microwave assisted hydrothermal method

    Directory of Open Access Journals (Sweden)

    Ivan Velasco-Davalos

    2016-06-01

    Full Text Available We report on a simple and fast procedure to create arrays of atomically flat terraces on single crystal SrTiO3 (111 substrates and the deposition of ferroelectric BiFeO3 thin films on such single-terminated surfaces. A microwave-assisted hydrothermal method in deionized water and ammonia solution selectively removes either (SrO34− or Ti4+ layers to ensure the same chemical termination on all terraces. Measured step heights of 0.225 nm (d111 and uniform contrast in the phase image of the terraces confirm the single termination in pure and Nb doped SrTiO3 single crystal substrates. Multiferroic BiFeO3 thin films were then deposited by the same microwave assisted hydrothermal process on Nb : SrTiO3 (111 substrates. Bi(NO33 and Fe(NO33 along with KOH served as the precursors solution. Ferroelectric behavior of the BiFeO3 films on Nb : SrTiO3 (100 substrates was verified by piezoresponse force microscopy.

  8. Depth resolved lattice-charge coupling in epitaxial BiFeO3 thin film

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyeon Jun; Lee, Sung Su; Kwak, Jeong Hun; Kim, Young-Min; Jeong, Hu Young; Borisevich, Albina Y.; Lee, Su Yong; Noh, Do Young; Kwon, Owoong; Kim, Yunseok; Jo, Ji Young

    2016-12-01

    For epitaxial films, a critical thickness (tc) can create a phenomenological interface between a strained bottom layer and a relaxed top layer. Here, we present an experimental report of how the tc in BiFeO3 thin films acts as a boundary to determine the crystalline phase, ferroelectricity, and piezoelectricity in 60 nm thick BiFeO3/SrRuO3/SrTiO3 substrate. We found larger Fe cation displacement of the relaxed layer than that of strained layer. In the time-resolved X-ray microdiffraction analyses, the piezoelectric response of the BiFeO3 film was resolved into a strained layer with an extremely low piezoelectric coefficient of 2.4 pm/V and a relaxed layer with a piezoelectric coefficient of 32 pm/V. The difference in the Fe displacements between the strained and relaxed layers is in good agreement with the differences in the piezoelectric coefficient due to the electromechanical coupling.

  9. Structural, magnetic, and ferroelectric properties of T-like cobalt-doped BiFeO3 thin films

    Science.gov (United States)

    Young, T.; Sharma, P.; Kim, D. H.; Ha, Thai Duy; Juang, Jenh-Yih; Chu, Y.-H.; Seidel, J.; Nagarajan, V.; Yasui, S.; Itoh, M.; Sando, D.

    2018-02-01

    We present a comprehensive study of the physical properties of epitaxial cobalt-doped BiFeO3 films ˜50 nm thick grown on (001) LaAlO3 substrates. X-ray diffraction and magnetic characterization demonstrate high quality purely tetragonal-like (T') phase films with no parasitic impurities. Remarkably, the step-and-terrace film surface morphology can be fully recovered following a local electric-field-induced rhombohedral-like to T' phase transformation. Local switching spectroscopy experiments confirm the ferroelectric switching to follow previously reported transition pathways. Critically, we show unequivocal evidence for conduction at domain walls between polarization variants in T'-like BFO, making this material system an attractive candidate for domain wall-based nanoelectronics.

  10. Evidence for oxygen vacancy or ferroelectric polarization induced switchable diode and photovoltaic effects in BiFeO3 based thin films

    International Nuclear Information System (INIS)

    Guo Yiping; Guo Bing; Dong Wen; Li Hua; Liu Hezhou

    2013-01-01

    The diode and photovoltaic effects of BiFeO 3 and Bi 0.9 Sr 0.1 FeO 3−δ polycrystalline thin films were investigated by poling the films with increased magnitude and alternating direction. It was found that both electromigration of oxygen vacancies and polarization flipping are able to induce switchable diode and photovoltaic effects. For the Bi 0.9 Sr 0.1 FeO 3−δ thin films with high oxygen vacancy concentration, reversibly switchable diode and photovoltaic effects can be observed due to the electromigration of oxygen vacancies under an electric field much lower than its coercive field. However, for the pure BiFeO 3 thin films with lower oxygen vacancy concentration, the reversibly switchable diode and photovoltaic effect is hard to detect until the occurrence of polarization flipping. The switchable diode and photovoltaic effects can be explained well using the concepts of Schottky-like barrier-to-Ohmic contacts resulting from the combination of oxygen vacancies and polarization. The sign of photocurrent could be independent of the direction of polarization when the modulation of the energy band induced by oxygen vacancies is large enough to offset that induced by polarization. The photovoltaic effect induced by the electromigration of oxygen vacancies is unstable due to the diffusion of oxygen vacancies or the recombination of oxygen vacancies with hopping electrons. Our work provides deep insights into the nature of diode and photovoltaic effects in ferroelectric films, and will facilitate the advanced design of switchable devices combining spintronic, electronic, and optical functionalities. (paper)

  11. Structure and electrical properties of (La, Zn) Co-doped BiFeO3 thin films prepared by using chemical solution deposition

    Science.gov (United States)

    Kim, Y. J.; Kim, H. J.; Kim, J. W.; Raghavan, C. M.; Kim, S. S.

    2012-08-01

    We prepared pure BiFeO3 (BFO) and (Bi0.9La0.1)(Fe0.975Zn0.025)O3- δ (BLFZO) thin films on Pt(111)/Ti/SiO2/Si(100) substrates by using a chemical solution deposition method. Improved electrical properties were observed in the co-doped BLFZO thin film. The leakage current density of the BLFZO thin film was four orders of magnitude lower than that of the pure BFO, 4.17 × 10-7 A/cm2 at 100 kV/cm. The remnant polarization (2 P r ) and the coercive electric field (2 E c ) of the BLFZO thin film were 97 µC/cm2 and 903 kV/cm at an applied electric field of 972 kV/cm and at a frequency of 1 kHz, and the values decreased with increasing measurement frequency to 63 µC/cm2 and 679 kV/cm at 10 kHz, respectively. Also, after 1.44 × 1010 cycles, a better fatigue endurance was observed in the BLFZO thin film, which was 90% of its initial value. We also confirmed that the remnant polarization (2 P r ) and the coercive electric field (2 E c ) were fairly saturated above a measurement frequency of 15 kHz for the BLFZO thin film.

  12. Enhancement of the electrical properties of (Eu,Zn) co-doped BiFeO3 thin films prepared by using chemical solution deposition

    Science.gov (United States)

    Kim, Youn-Jang; Kim, Jin Won; Kim, Hae Jin; Kim, Sang Su

    2013-04-01

    We prepared pure BiFeO3 (BFO) and (Bi0.9Eu0.1)(Fe0.975Zn0.025)O3-δ (BEFZO) thin films on Pt(111)/Ti/SiO2/Si(100) substrates by using a chemical solution deposition method. Improved electrical properties were observed in the co-doped BEFZO thin film. The leakage current density of the BEFZO thin film was three orders of magnitude lower than that of the pure BFO, 3.93 × 10-6 A/cm2 at 100 kV/cm. The remnant polarization (2 P r ) and the coercive electric field (2 E c ) of the BEFZO thin film were 42 µC/cm2 and 898 kV/cm at an applied electric field of 1000 kV/cm and at a frequency of 1 kHz and the values decreased with increasing measurement frequency to 18 µC/cm2 and 866 kV/cm at 10 kHz, respectively. Also, the fatigue endurances were evaluated at peak voltages of 8-10 V after 1.44 × 1010 cycles in the BEFZO thin films and were 70 ˜ 90% of the initial values. We also confirmed that the 2 P r was fairly saturated at measurement frequency about 30 kHz for the BEFZO thin film.

  13. Resistive switching properties of Ce and Mn co-doped BiFeO3 thin films for nonvolatile memory application

    Directory of Open Access Journals (Sweden)

    Zhenhua Tang

    2013-12-01

    Full Text Available The Ce and Mn co-doped BiFeO3 (BCFMO thin films were synthesized on Pt/Ti/SiO2/Si substrates using a sol-gel method. The unipolar resistive switching (URS and bipolar resistive switching (BRS behaviors were observed in the Pt/BCFMO/Pt device structure, which was attributed to the formation/rupture of metal filaments. The fabricated device exhibits a large ROFF/RON ratio (>80, long retention time (>105 s and low programming voltages (<1.5 V. Analysis of linear fitting current-voltage curves suggests that the space charge limited leakage current (SCLC and Schottky emission were observed as the conduction mechanisms of the devices.

  14. Highly textured Sr, Nb co-doped BiFeO3 thin films grown on SrRuO3/Si substrates by rf- sputtering

    International Nuclear Information System (INIS)

    Ostos, C.; Raymond, O.; Siqueiros, J. M.; Suarez-Almodovar, N.; Bueno-Baques, D.; Mestres, L.

    2011-01-01

    In this study, (011)-highly oriented Sr, Nb co-doped BiFeO 3 (BFO) thin films were successfully grown on SrRuO 3 /Si substrates by rf-magnetron sputtering. The presence of parasite magnetic phases was ruled out based on the high resolution x-ray diffraction data. BFO films exhibited a columnar-like grain growth with rms surface roughness values of ≅5.3 nm and average grain sizes of ≅65-70 nm for samples with different thicknesses. Remanent polarization values (2P r ) of 54 μC cm -2 at room temperature were found for the BFO films with a ferroelectric behavior characteristic of an asymmetric device structure. Analysis of the leakage mechanisms for this structure in negative bias suggests Schottky injection and a dominant Poole-Frenkel trap-limited conduction at room temperature. Oxygen vacancies and Fe 3+ /Fe 2+ trap centers are consistent with the surface chemical bonding states analysis from x-ray photoelectron spectroscopy data. The (011)-BFO/SrRuO 3 /Si film structure exhibits a strong magnetic interaction at the interface between the multiferroic film and the substrate layer where an enhanced ferromagnetic response at 5 K was observed. Zero-field cooled (ZFC) and field cooled (FC) magnetization curves of this film system revealed a possible spin glass behavior at spin freezing temperatures below 30 K depending on the BFO film thickness.

  15. Thin film composites in the BiFeO3–Bi4Ti3O12 system obtained by an aqueous solution-gel deposition methodology

    Directory of Open Access Journals (Sweden)

    Carlos Gumiel

    2018-01-01

    Full Text Available Thin film multiferroic composites, with a high quantity of interfaces between the different materials, represent a more feasible alternative to single phase systems in which the multifunctional response is usually hampered due to intrinsic physical constraints. Nowadays some of these composites can be produced by applying deposition techniques such as PLD, CVD, MBE or the like, which allow a high degree of crystallographic control. However, despite their effectiveness, all these techniques also involve a high consumption of energy in terms of temperature and/or vacuum. Within this frame, the present contribution proposes a sustainable chemical solution deposition process to prepare thin films of the multiferroic BiFeO3–Bi4Ti3O12 composite system. More specifically an aqueous solution-gel plus spin-coating methodology is employed which also avoids the organic solvents typically used in a conventional sol–gel method, so further keeping an eye on the environmentally friendly conditions. Attempts are conducted that demonstrate how by systematically controlling the processing parameters it is possible to obtain thin film composites with a promising 3-3 type connectivity at temperatures as low as 600 °C.

  16. Thin film composites in the BiFeO3–Bi4Ti3O12 system obtained by an aqueous solution-gel deposition methodology

    International Nuclear Information System (INIS)

    Gumiel, C.; Vranken, T.; Bernardo, M.S.; Jardiel, T.; Hardy, A.; Van Bael, M.K.; Peiteado, M.

    2018-01-01

    Thin film multiferroic composites, with a high quantity of interfaces between the different materials, represent a more feasible alternative to single phase systems in which the multifunctional response is usually hampered due to intrinsic physical constraints. Nowadays some of these composites can be produced by applying deposition techniques such as PLD, CVD, MBE or the like, which allow a high degree of crystallographic control. However, despite their effectiveness, all these techniques also involve a high consumption of energy in terms of temperature and/or vacuum. Within this frame, the present contribution proposes a sustainable chemical solution deposition process to prepare thin films of the multiferroic BiFeO3–Bi4Ti3O12 composite system. More specifically an aqueous solution-gel plus spin-coating methodology is employed which also avoids the organic solvents typically used in a conventional sol–gel method, so further keeping an eye on the environmentally friendly conditions. Attempts are conducted that demonstrate how by systematically controlling the processing parameters it is possible to obtain thin film composites with a promising 3-3 type connectivity at temperatures as low as 600°C. [es

  17. Absence of morphotropic phase boundary effects in BiFeO3-PbTiO3 thin films grown via a chemical multilayer deposition method

    Science.gov (United States)

    Gupta, Shashaank; Bhattacharjee, Shuvrajyoti; Pandey, Dhananjai; Bansal, Vipul; Bhargava, Suresh K.; Peng, Ju Lin; Garg, Ashish

    2011-07-01

    We report an unusual behavior observed in (BiFeO3)1- x -(PbTiO3) x (BF- xPT) thin films prepared using a multilayer chemical solution deposition method. Films of different compositions were grown by depositing several bilayers of BF and PT precursors of varying BF and PT layer thicknesses followed by heat treatment in air. X-ray diffraction showed that samples of all compositions show mixing of two compounds resulting in a single-phase mixture, also confirmed by transmission electron microscopy. In contrast to bulk compositions, samples show a monoclinic (MA-type) structure suggesting disappearance of the morphotropic phase boundary (MPB) at x=0.30 as observed in the bulk. This is accompanied by the lack of any enhancement of the remanent polarization at the MPB, as shown by the ferroelectric measurements. Magnetic measurements showed an increase in the magnetization of the samples with increasing BF content. Significant magnetization in the samples indicates melting of spin spirals in the BF- xPT films, arising from a random distribution of iron atoms. Absence of Fe2+ ions was corroborated by X-ray photoelectron spectroscopy measurements. The results illustrate that thin film processing methodology significantly changes the structural evolution, in contrast to predictions from the equilibrium phase diagram, besides modifying the functional characteristics of the BP- xPT system dramatically.

  18. Electrical and piezoelectric properties of BiFeO3 thin films grown on SrxCa1−xRuO3-buffered SrTiO3 substrates

    KAUST Repository

    Yao, Yingbang

    2012-06-01

    (001)-oriented BiFeO 3 (BFO) thin films were grown on Sr xCa 1-xRuO 3- (SCRO; x = 1, 0.67, 0.33, 0) buffered SrTiO 3 (001) substrates using pulsed laser deposition. The microstructural, electrical, ferroelectric, and piezoelectric properties of the thin films were considerably affected by the buffer layers. The interface between the BFO films and the SCRO-buffer layer was found to play a dominant role in determining the electrical and piezoelectric behaviors of the films. We found that films grown on SrRuO 3-buffer layers exhibited minimal electrical leakage while films grown on Sr 0.33Ca 0.67RuO 3-buffer layers had the largest piezoelectric response. The origin of this difference is discussed. © 2012 American Institute of Physics.

  19. Dipole pinning effect on photovoltaic characteristics of ferroelectric BiFeO3 films

    Science.gov (United States)

    Biswas, P. P.; Thirmal, Ch.; Pal, S.; Murugavel, P.

    2018-01-01

    Ferroelectric bismuth ferrite is an attractive candidate for switchable devices. The effect of dipole pinning due to the oxygen vacancy layer on the switching behavior of the BiFeO3 thin film fabricated by the chemical solution deposition method was studied after annealing under air, O2, and N2 environment. The air annealed film showed well defined and dense grains leading to a lower leakage current and superior electrical properties compared to the other two films. The photovoltage and transient photocurrent measured under positive and negative poling elucidated the switching nature of the films. Though the air and O2 annealed films showed a switchable photovoltaic response, the response was severely affected by oxygen vacancies in the N2 annealed film. In addition, the open circuit voltage was found to be mostly dependent on the polarization of BiFeO3 rather than the Schottky barriers at the interface. This work provides an important insight into the effect of dipole pinning caused by oxygen vacancies on the switchable photovoltaic effect of BiFeO3 thin films along with the importance of stoichiometric, defect free, and phase pure samples to facilitate meaningful practical applications.

  20. Multiferroic properties of BiFeO3/Bi4Ti3O12 double-layered thin films fabricated by chemical solution deposition

    International Nuclear Information System (INIS)

    Yi, Seung Woo; Kim, Sang Su; Kim, Jin Won; Jo, Hyun Kyung; Do, Dalhyun; Kim, Won-Jeong

    2009-01-01

    Multiferroic BiFeO 3 /Bi 4 Ti 3 O 12 (BFO/BTO) double-layered film was fabricated on a Pt(111)/Ti/SiO 2 /Si(100) substrate by a chemical solution deposition method. The effect of an interfacial BTO layer on electrical and magnetic properties of BFO was investigated by comparing those of pure BFO and BTO films prepared by the same condition. The X-ray diffraction result showed that no additional phase was formed in the double-layered film, except BFO and BTO phases. The remnant polarization (2P r ) of the double-layered film capacitor was 100 μC/cm 2 at 250 kV/cm, which is much larger than that of the pure BFO film capacitor. The magnetization-magnetic field hysteresis loop revealed weak ferromagnetic response with remnant magnetization (2M r ) of 0.4 kA/m. The values of dielectric constant and dielectric loss of the double-layered film capacitor were 240 and 0.03 at 100 kHz, respectively. Leakage current density measured from the double-layered film capacitor was 6.1 x 10 -7 A/cm 2 at 50 kV/cm, which is lower than the pure BFO and BTO film capacitors.

  1. Optical, ferroelectric and magnetic properties of multiferroelectric BiFeO3-(K0.5Na0.5)0.4(Sr 0.6Ba0.4)0.8Nb2O6 thin films

    KAUST Repository

    Yao, Yingbang

    2014-02-01

    Multiferroic BiFeO3-(K0.5Na0.5) 0.4(Sr0.6Ba0.4)0.8Nb 2O6 (BFO-KNSBN) trilayer thin films, were epitaxially grown on MgO(0 0 1) and SrTiO3(0 0 1) by using pulsed laser deposition (PLD). Their ferroelectric, magnetic, dielectric and optical properties were investigated. It was found that both ferroelectric polarization and dielectric constant of the films were enhanced by introducing KNSBN as a barrier layer. Meanwhile, ferromagnetism of BFO was maintained. More interestingly, a double hysteresis magnetic loop was observed in the KNSBN-BFO-KNSBN trilayer films, where exchange bias and secondary phase in the BFO layer played crucial roles. Interactions between adjacent layers were revealed by temperature-dependent Raman spectroscopic measurements. © 2013 Elsevier B.V. All rights reserved.

  2. Polarized Raman study on the lattice structure of BiFeO3 films prepared by pulsed laser deposition

    KAUST Repository

    Yang, Yang; Yao, Yingbang; Zhang, Q.; Zhang, Xixiang

    2014-01-01

    Polarized Raman spectroscopy was used to study the lattice structure of BiFeO3 films on different substrates prepared by pulsed laser deposition. Interestingly, the Raman spectra of BiFeO3 films exhibit distinct polarization dependences

  3. Joining Chemical Pressure and Epitaxial Strain to Yield Y-doped BiFeO3 Thin Films with High Dielectric Response

    Science.gov (United States)

    Scarisoreanu, N. D.; Craciun, F.; Birjega, R.; Ion, V.; Teodorescu, V. S.; Ghica, C.; Negrea, R.; Dinescu, M.

    2016-05-01

    BiFeO3 is one of the most promising multiferroic materials but undergoes two major drawbacks: low dielectric susceptibility and high dielectric loss. Here we report high in-plane dielectric permittivity (ε’ ∼2500) and low dielectric loss (tan δ priced target.

  4. Self-Poling of BiFeO3 Thick Films.

    Science.gov (United States)

    Khomyakova, Evgeniya; Sadl, Matej; Ursic, Hana; Daniels, John; Malic, Barbara; Bencan, Andreja; Damjanovic, Dragan; Rojac, Tadej

    2016-08-03

    Bismuth ferrite (BiFeO3) is difficult to pole because of the combination of its high coercive field and high electrical conductivity. This problem is particularly pronounced in thick films. The poling, however, must be performed to achieve a large macroscopic piezoelectric response. This study presents evidence of a prominent and reproducible self-poling effect in few-tens-of-micrometer-thick BiFeO3 films. Direct and converse piezoelectric measurements confirmed that the as-sintered BiFeO3 thick films yield d33 values of up to ∼20 pC/N. It was observed that a significant self-poling effect only appears in cases when the films are heated and cooled through the ferroelectric-paraelectric phase transition (Curie temperature TC ∼ 820 °C). These self-poled films exhibit a microstructure with randomly oriented columnar grains. The presence of a compressive strain gradient across the film thickness cooled from above the TC was experimentally confirmed and is suggested to be responsible for the self-poling effect. Finally, the macroscopic d33 response of the self-poled BiFeO3 film was characterized as a function of the driving-field frequency and amplitude.

  5. Electric and Magnetic Properties of Sputter Deposited BiFeO3 Films

    Directory of Open Access Journals (Sweden)

    N. Siadou

    2013-01-01

    Full Text Available Polycrystalline BiFeO3 films have been magnetron sputter deposited at room temperature and subsequently heat-treated ex situ at temperatures between 400 and 700°C. The deposition was done in pure Ar atmosphere, as the use of oxygen-argon mixture was found to lead to nonstoichiometric films due to resputtering effects. At a target-to-substrate distance d=2′′ the BiFeO3 structure can be obtained in larger range process gas pressures (2–7 mTorr but the films do not show a specific texture. At d=6′′ codeposition from BiFeO3 and Bi2O3 has been used. Films sputtered at low rate tend to grow with the (001 texture of the pseudo-cubic BiFeO3 structure. As the film structure does not depend on epitaxy similar results are obtained on different substrates. A result of the volatility of Bi, Bi rich oxide phases occur after heat treatment at high temperatures. A Bi2SiO5 impurity phase forms on the substrate side, and does not affect the properties of the main phase. Despite the deposition on amorphous silicon oxide substrate weak ferromagnetism phenomena and displaced loops have been observed at low temperatures showing that their origin is not strain. Ba, La, Ca, and Sr doping suppress the formation of impurity phases and leakage currents.

  6. Polarized Raman study on the lattice structure of BiFeO3 films prepared by pulsed laser deposition

    KAUST Repository

    Yang, Yang

    2014-11-01

    Polarized Raman spectroscopy was used to study the lattice structure of BiFeO3 films on different substrates prepared by pulsed laser deposition. Interestingly, the Raman spectra of BiFeO3 films exhibit distinct polarization dependences. The symmetries of the fundamental Raman modes in 50-700 cm-1 were identified based on group theory. The symmetries of the high order Raman modes in 900-1500 cm-1 of BiFeO3 are determined for the first time, which can provide strong clarifications to the symmetry of the fundamental peaks in 400-700 cm-1 in return. Moreover, the lattice structures of BiFeO3 films are identified consequently on the basis of Raman spectroscopy. BiFeO3 films on SrRuO3 coated SrTiO3 (0 0 1) substrate, CaRuO3 coated SrTiO3 (0 0 1) substrate and tin-doped indium oxide substrate are found to be in the rhombohedral structure, while BiFeO3 film on SrRuO3 coated Nb: SrTiO3 (0 0 1) substrate is in the monoclinic structure. Our results suggest that polarized Raman spectroscopy would be a feasible tool to study the lattice structure of BiFeO3 films.

  7. Electric Field Controlled Magnetism in BiFeO3/Ferromagnet Films

    Science.gov (United States)

    Holcomb, M. B.; Chu, Y. H.; Martin, L. W.; Gajek, M.; Seidel, J.; Ramesh, R.; Scholl, A.; Fraile-Rodriguez, A.

    2008-03-01

    Electric field control of magnetism is a hot technological topic at the moment due to its potential to revolutionize today's devices. Magnetoelectric materials, those having both electric and magnetic order and the potential for coupling between the two, are a promising avenue to approach electric control. BiFeO3, both a ferroelectric and an antiferromagnet, is the only single phase room temperature magnetoelectric that is currently known. In addition to other possibilities, its multiferroic nature has potential in the very active field of exchange bias, where an antiferromagnetic thin film pins the magnetic direction of an adjoining ferromagnetic layer. Since this antiferromagnet is electrically tunable, this coupling could allow electric-field control of the ferromagnetic magnetization. Direction determination of antiferromagnetic domains in BFO has recently been shown using linear and circular dichroism studies. Recently, this technique has been extended to look at the magnetic domains of a ferromagnetic grown on top of BFO. The clear magnetic changes induced by application of electric fields reveal the possibility of electric control.

  8. Effects of Interfaces on the Structure and Novel Physical Properties in Epitaxial Multiferroic BiFeO3 Ultrathin Films

    Directory of Open Access Journals (Sweden)

    Chuanwei Huang

    2014-07-01

    Full Text Available In functional oxide films, different electrical/mechanical boundaries near film surfaces induce rich phase diagrams and exotic phenomena. In this paper, we review some key points which underpin structure, phase transition and related properties in BiFeO3 ultrathin films. Compared with the bulk counterparts, we survey the recent results of epitaxial BiFeO3 ultrathin films to illustrate how the atomic structure and phase are markedly influenced by the interface between the film and the substrate, and to emphasize the roles of misfit strain and depolarization field on determining the domain patterns, phase transformation and associated physical properties of BiFeO3 ultrathin films, such as polarization, piezoelectricity, and magnetism. One of the obvious consequences of the misfit strain on BiFeO3 ultrathin films is the emergence of a sequence of phase transition from tetragonal to mixed tetragonal & rhombohedral, the rhombohedral, mixed rhombohedral & orthorhombic, and finally orthorhombic phases. Other striking features of this system are the stable domain patterns and the crossover of 71° and 109° domains with different electrical boundary conditions on the film surface, which can be controlled and manipulated through the depolarization field. The external field-sensitive enhancements of properties for BiFeO3 ultrathin films, including the polarization, magnetism and morphotropic phase boundary-relevant piezoelectric response, offer us deeper insights into the investigations of the emergent properties and phenomena of epitaxial ultrathin films under various mechanical/electrical constraints. Finally, we briefly summarize the recent progress and list open questions for future study on BiFeO3 ultrathin films.

  9. Controllable Photovoltaic Effect of Microarray Derived from Epitaxial Tetragonal BiFeO3 Films.

    Science.gov (United States)

    Lu, Zengxing; Li, Peilian; Wan, Jian-Guo; Huang, Zhifeng; Tian, Guo; Pan, Danfeng; Fan, Zhen; Gao, Xingsen; Liu, Jun-Ming

    2017-08-16

    Recently, the ferroelectric photovoltaic (FePV) effect has attracted great interest due to its potential in developing optoelectronic devices such as solar cell and electric-optical sensors. It is important for actual applications to realize a controllable photovoltaic process in ferroelectric-based materials. In this work, we prepared well-ordered microarrays based on epitaxially tetragonal BiFeO 3 (T-BFO) films by the pulsed laser deposition technique. The polarization-dependent photocurrent image was directly observed by a conductive atomic force microscope under ultraviolet illumination. By choosing a suitable buffer electrode layer and controlling the ferroelectric polarization in the T-BFO layer, we realized the manipulation of the photovoltaic process. Moreover, based on the analysis of the band structure, we revealed the mechanism of manipulating the photovoltaic process and attributed it to the competition between two key factors, i.e., the internal electric field caused by energy band alignments at interfaces and the depolarization field induced by the ferroelectric polarization in T-BFO. This work is very meaningful for deeply understanding the photovoltaic process of BiFeO 3 -based devices at the microscale and provides us a feasible avenue for developing data storage or logic switching microdevices based on the FePV effect.

  10. Influence of Co doping on structural, optical and magnetic properties of BiFeO3 films deposited on quartz substrates by sol-gel method

    Science.gov (United States)

    Peng, Lin; Deng, Hongmei; Tian, Jianjun; Ren, Qing; Peng, Cheng; Huang, Zhipeng; Yang, Pingxiong; Chu, Junhao

    2013-03-01

    Multiferroic BiFe1-xCoxO3 (x = 0, 0.03, 0.05, 0.1) thin films have been prepared on quartz substrates using a sol-gel technique. X-ray diffraction data confirms that Co atoms have been successfully incorporated into the host lattice. The scanning electron microscopy (SEM) exhibits that the surface morphologies of BiFe0.97Co0.03O3 and BiFe0.95Co0.05O3 thin films become more compact and uniform. With increasing Co dopant, the position of A1-1 and E-4 modes shift towards the lower wavenumber indicates that Co doping induces structural distortion of BiFeO3. With increasing Co composition, the fundamental absorption edges of BiFe1-xCoxO3 films show red shift. Furthermore, transmittance spectra demonstrates that the optical band gap of BiFe1-xCoxO3 films decreases from 2.66 eV to 2.53 eV with the increase of Co from x = 0 to 0.1. At the wavelength of 720 nm, the refractive index decreases and the extinction coefficient increases with increasing the amount of Co. Optical properties reveal that Co doping in BiFeO3 provides preliminary research for optoelectronic devices and infrared detectors. Compared with BiFeO3 prepared under similar conditions, the remanent magnetization Mr of BiFe1-xCoxO3 (x = 0.03, 0.05, 0.1) thin films significantly enhanced, which provides potential applications in information storage.

  11. Pr and Gd co-doped bismuth ferrite thin films with enhanced ...

    Indian Academy of Sciences (India)

    in Pr content, the crystal structures of BPGFO thin films retain rhombohedral (R3c) symmetry accompanied by structure distortion. ... Pr and Gd co-modified BiFeO3 thin film; ferroelectric properties; sol-gel. 1. Introduction. In recent years, great attention has been paid to single- phase BiFeO3 (BFO) multiferroic materials ...

  12. Optical, ferroelectric and magnetic properties of multiferroelectric BiFeO3-(K0.5Na0.5)0.4(Sr 0.6Ba0.4)0.8Nb2O6 thin films

    KAUST Repository

    Yao, Yingbang; Mak, C. L.

    2014-01-01

    were investigated. It was found that both ferroelectric polarization and dielectric constant of the films were enhanced by introducing KNSBN as a barrier layer. Meanwhile, ferromagnetism of BFO was maintained. More interestingly, a double hysteresis

  13. Electrical and piezoelectric properties of BiFeO3 thin films grown on SrxCa1−xRuO3-buffered SrTiO3 substrates

    KAUST Repository

    Yao, Yingbang; Chen, Long; Wang, Zhihong; Alshareef, Husam N.; Zhang, Xixiang

    2012-01-01

    on SrRuO 3-buffer layers exhibited minimal electrical leakage while films grown on Sr 0.33Ca 0.67RuO 3-buffer layers had the largest piezoelectric response. The origin of this difference is discussed. © 2012 American Institute of Physics.

  14. Electric modulation of conduction in multiferroic Ca-doped BiFeO3 films

    Science.gov (United States)

    Yang, C.-H.; Seidel, J.; Kim, S. Y.; Rossen, P. B.; Yu, P.; Gajek, M.; Chu, Y. H.; Martin, L. W.; Holcomb, M. B.; He, Q.; Maksymovych, P.; Balke, N.; Kalinin, S. V.; Baddorf, A. P.; Basu, S. R.; Scullin, M. L.; Ramesh, R.

    2009-06-01

    Many interesting materials phenomena such as the emergence of high-Tc superconductivity in the cuprates and colossal magnetoresistance in the manganites arise out of a doping-driven competition between energetically similar ground states. Doped multiferroics present a tantalizing evolution of this generic concept of phase competition. Here, we present the observation of an electronic conductor-insulator transition by control of band-filling in the model antiferromagnetic ferroelectric BiFeO3 through Ca doping. Application of electric field enables us to control and manipulate this electronic transition to the extent that a p-n junction can be created, erased and inverted in this material. A `dome-like' feature in the doping dependence of the ferroelectric transition is observed around a Ca concentration of ~1/8, where a new pseudo-tetragonal phase appears and the electric modulation of conduction is optimized. Possible mechanisms for the observed effects are discussed on the basis of the interplay of ionic and electronic conduction. This observation opens the door to merging magnetoelectrics and magnetoelectronics at room temperature by combining electronic conduction with electric and magnetic degrees of freedom already present in the multiferroic BiFeO3.

  15. Adsorption-controlled growth of BiFeO3 by MBE and integration with wide band gap semiconductors.

    Science.gov (United States)

    Ihlefeld, Jon F; Tian, Wei; Liu, Zi-Kui; Doolittle, W Alan; Bernhagen, Margitta; Reiche, Peter; Uecker, Reinhard; Ramesh, Ramamoorthy; Schlom, Darrell G

    2009-08-01

    BiFeO3 thin films have been deposited on (001) SrTiO3, (101) DyScO3, (011) DyScO3, (0001) AlGaN/GaN, and (0001) 6H-SiC single crystal substrates by reactive molecular beam epitaxy in an adsorption-controlled growth regime. This is achieved by supplying a bismuth over-pressure and utilizing the differential vapor pressures between bismuth oxides and BiFeO3 to control stoichiometry in accordance with thermodynamic calculations. Four-circle x-ray diffraction and transmission electron microscopy reveal phase-pure, epitaxial films with rocking curve full width at half maximum values as narrow as 7.2 arc seconds (0.002 degrees). Epitaxial growth of (0001)-oriented BiFeO3 thin films on (0001) GaN, including AlGaN HEMT structures, and (0001) SiC has been realized using intervening epitaxial (111) SrTiO3 / (100) TiO2 buffer layers. The epitaxial BiFeO3 thin films have 2 in-plane orientations: [1120] BiFeO3 || [1120] GaN (SiC) plus a twin variant related by a 180 degrees in-plane rotation. This epitaxial integration of the ferroelectric with the highest known polarization, BiFeO3, with high bandgap semiconductors is an important step toward novel field-effect devices.

  16. Excitation of spin waves in BiFeO3 multiferroic film by the slot line transducer

    Science.gov (United States)

    Korneev, V. I.; Popkov, A. F.; Solov'yov, S. V.

    2018-01-01

    Analysis of the efficiency of magnetoelectric excitation of spin-waves in BiFeO3 multiferroic films by a slot line is performed based on the solution of dynamic Ginzburg-Landau equations for the antiferromagnetic vector. The excitation efficiency is determined by the magnitude of the conversion coefficient of the electromagnetic wave to the spin wave by the slot line transducer or in other words, losses on conversion in the slot line. Calculations are made for a homogeneous antiferromagnetic state of the multiferroic in the presence of a sufficiently large magnetic field and for a spatially modulated spin state (SMSS) at zero magnetic field. It is shown that in the case of a homogeneous antiferromagnetic state, the losses on the excitation of spin waves exceed the excitation efficiency in the SMSS state; however, as the frequency approaches the spin excitation gap, it falls and becomes lower than in the SMSS state. Spin wave excitation in the presence of antiferromagnetic cycloid strongly depends on the relation of the slot width of the transducer to the cycloid periodicity and on the magnitude of the shift of the position of the transducer along the cycloid on its period. The usage of multiferroics for delay lines in the considered frequency range from 100 to 600 GHz requires significant reduction in conversion and propagation losses. More promising seems multiferroic usage in phase shifters and switches for this range.

  17. Control of oxygen octahedral rotation in BiFeO3 films using modulation of SrRuO3 bottom electrode layer

    Science.gov (United States)

    Lee, Sungsu; Jo, Ji Young

    2015-03-01

    Oxygen octahedral rotation of multiferroic BiFeO3 (BFO) has attracted great attention due to changes of electrical and magnetic properties. Coupling of octahedral rotation in BFO-bottom electrode layer interface remains unexplored. Recently, there have been reported the control of octahedral rotation in SrRuO3 (SRO) film on SrTiO3 (001) substrate by coherently controlling the oxygen pressure during growth and interfacial coupling. Here we demonstrate that the octahedral rotation of BFO film is changed using tetragonal a0a0c- tilted-SRO bottom electrodes. In this work, BFO/SRO heterostructure is fabricated to SrTiO3 (001) single crystal substrates by pulsed laser deposition at different oxygen partial pressures. The rotation pattern of FeO6 and the structural symmetry are identified from half-integer reflections using high-resolution X-ray diffraction. The effects depending on octahedral tilting of BFO films on the magnetic and ferroelectric properties will be presented.

  18. Simultaneous achievement of high dielectric constant and low temperature dependence of capacitance in (111-oriented BaTiO3-Bi(Mg0.5Ti0.5O3-BiFeO3 solid solution thin films

    Directory of Open Access Journals (Sweden)

    Junichi Kimura

    2016-01-01

    Full Text Available The temperature dependence of the capacitance of (111c-oriented (0.90–xBaTiO3-0.10Bi(Mg0.5Ti0.5O3-xBiFeO3 solid solution films is investigated. These films are prepared on (111cSrRuO3/(111Pt/TiO2/SiO2/(100Si substrates by the chemical solution deposition technique. All the films have perovskite structures and the crystal symmetry at room temperature varies with increasing x ratio, from pseudocubic when x = 0–0.30 to rhombohedral when x = 0.50–0.90. The pseudocubic phase shows a high relative dielectric constant (εr (ranging between 400 and 560 at room temperature and an operating frequency of 100 kHz and a low temperature dependence of capacitance up to 400°C, while maintaining a dielectric loss (tan δ value of less than 0.2 at 100 kHz. In contrast, εr for the rhombohedral phase increases monotonically with increasing temperature up to 250°C, and increasingly high tan δ values are recorded at higher temperatures. These results indicate that pseudocubic (0.90–xBaTiO3-0.10Bi(Mg0.5Ti0.5O3-xBiFeO3 solid solution films with (111 orientation are suitable candidates for high-temperature capacitor applications.

  19. Effect of strain on voltage-controlled magnetism in BiFeO3-based heterostructures

    Science.gov (United States)

    Wang, J. J.; Hu, J. M.; Yang, T. N.; Feng, M.; Zhang, J. X.; Chen, L. Q.; Nan, C. W.

    2014-01-01

    Voltage-modulated magnetism in magnetic/BiFeO3 heterostructures can be driven by a combination of the intrinsic ferroelectric-antiferromagnetic coupling in BiFeO3 and the antiferromagnetic-ferromagnetic exchange interaction across the heterointerface. However, ferroelectric BiFeO3 film is also ferroelastic, thus it is possible to generate voltage-induced strain in BiFeO3 that could be applied onto the magnetic layer across the heterointerface and modulate magnetism through magnetoelastic coupling. Here, we investigated, using phase-field simulations, the role of strain in voltage-controlled magnetism for these BiFeO3-based heterostructures. It is predicted, under certain condition, coexistence of strain and exchange interaction will result in a pure voltage-driven 180° magnetization reversal in BiFeO3-based heterostructures. PMID:24686503

  20. thin films

    Indian Academy of Sciences (India)

    microscopy (SEM) studies, respectively. The Fourier transform ... Thin films; chemical synthesis; hydrous tin oxide; FTIR; electrical properties. 1. Introduction ... dehydrogenation of organic compounds (Hattori et al 1987). .... SEM images of (a) bare stainless steel and (b) SnO2:H2O thin film on stainless steel substrate at a ...

  1. Rewritable ferroelectric vortex pairs in BiFeO3

    Science.gov (United States)

    Li, Yang; Jin, Yaming; Lu, Xiaomei; Yang, Jan-Chi; Chu, Ying-Hao; Huang, Fengzhen; Zhu, Jinsong; Cheong, Sang-Wook

    2017-08-01

    Ferroelectric vortex in multiferroic materials has been considered as a promising alternative to current memory cells for the merit of high storage density. However, the formation of regular natural ferroelectric vortex is difficult, restricting the achievement of vortex memory device. Here, we demonstrated the creation of ferroelectric vortex-antivortex pairs in BiFeO3 thin films by using local electric field. The evolution of the polar vortex structure is studied by piezoresponse force microscopy at nanoscale. The results reveal that the patterns and stability of vortex structures are sensitive to the poling position. Consecutive writing and erasing processes cause no influence on the original domain configuration. The Z4 proper coloring vortex-antivortex network is then analyzed by graph theory, which verifies the rationality of artificial vortex-antivortex pairs. This study paves a foundation for artificial regulation of vortex, which provides a possible pathway for the design and realization of non-volatile vortex memory devices and logical devices.

  2. Refractive index dispersion of swift heavy ion irradiated BFO thin films using Surface Plasmon Resonance technique

    International Nuclear Information System (INIS)

    Paliwal, Ayushi; Sharma, Savita; Tomar, Monika; Singh, Fouran; Gupta, Vinay

    2016-01-01

    Highlights: • Investigated the optical properties of BiFeO_3 (BFO) thin films after irradiation using SPR. • Otto configuration has been used to excite the surface plasmons using gold metal thin film. • BFO thin films were prepared by sol–gel spin coating technique. • Examined the refractive index dispersion of pristine and irradiated BFO thin film. - Abstract: Swift heavy ion irradiation (SHI) is an effective technique to induce defects for possible modifications in the material properties. There is growing interest in studying the optical properties of multiferroic BiFeO_3 (BFO) thin films for optoelectronic applications. In the present work, BFO thin films were prepared by sol–gel spin coating technique and were irradiated using the 15 UD Pelletron accelerator with 100 MeV Au"9"+ ions at a fluence of 1 × 10"1"2 ions cm"−"2. The as-grown films became rough and porous on ion irradiation. Surface Plasmon Resonance (SPR) technique has been identified as a highly sensitive and powerful technique for studying the optical properties of a dielectric material. Optical properties of BFO thin films, before and after irradiation were studied using SPR technique in Otto configuration. Refractive index is found to be decreasing from 2.27 to 2.14 on ion irradiation at a wavelength of 633 nm. Refractive index dispersion of BFO thin film (from 405 nm to 633 nm) before and after ion radiation was examined.

  3. Ferroelectric and electrical characterization of multiferroic BiFeO3 at the single nanoparticle level

    Energy Technology Data Exchange (ETDEWEB)

    Vasudevan, Rama K [ORNL; Bogle, K A [University of New South Wales, Sydney, Australia; Kumar, Amit [ORNL; Jesse, Stephen [ORNL; Magaraggia, R [University of Glasgow; Stamps, R [University of Glasgow; Ogale, S [National Chemical Laboratory, India; Potdar, H S [National Chemical Laboratory, India

    2011-01-01

    Ferroelectric BiFeO3 (BFO) nanoparticles deposited on epitaxial substrates of SrRuO3 (SRO) and La1xSrxMnO3 (LSMO) were studied using band excitation piezoresponse spectroscopy (BEPS), piezoresponse force microscopy (PFM), and ferromagnetic resonance (FMR). BEPS confirms that the nanoparticles are ferroelectric in nature. Switching behavior of nanoparticle clusters were studied and showed evidence for inhomogeneous switching. The dimensionality of domains within nanoparticles was found to be fractal in nature, with a dimensionality constant of 1.4, on par with ferroelectric BFO thin-films under 100 nm in thickness. Ferromagnetic resonance studies indicate BFO nanoparticles only weakly affect the magnetic response of LSMO.

  4. Ferroelectric and electrical characterization of multiferroic BiFeO3 at the single nanoparticle level

    Science.gov (United States)

    Vasudevan, R. K.; Bogle, K. A.; Kumar, A.; Jesse, S.; Magaraggia, R.; Stamps, R.; Ogale, S. B.; Potdar, H. S.; Nagarajan, V.

    2011-12-01

    Ferroelectric BiFeO3 (BFO) nanoparticles deposited on epitaxial substrates of SrRuO3 (SRO) and La1-xSrxMnO3 (LSMO) were studied using band excitation piezoresponse spectroscopy (BEPS), piezoresponse force microscopy (PFM), and ferromagnetic resonance (FMR). BEPS confirms that the nanoparticles are ferroelectric in nature. Switching behavior of nanoparticle clusters were studied and showed evidence for inhomogeneous switching. The dimensionality of domains within nanoparticles was found to be fractal in nature, with a dimensionality constant of ˜1.4, on par with ferroelectric BFO thin-films under 100 nm in thickness. Ferromagnetic resonance studies indicate BFO nanoparticles only weakly affect the magnetic response of LSMO.

  5. Interfacial effects revealed by ultrafast relaxation dynamics in BiFeO 3 / YBa 2 Cu 3 O 7 bilayers

    KAUST Repository

    Springer, D.

    2016-02-12

    The temperature dependence of the relaxation dynamics in the bilayer thin film heterostructure composed of multiferroic BiFeO3 (BFO) and superconducting YBa2Cu3O7 (YBCO) grown on a (001) SrTiO3 substrate is studied by a time-resolved pump-probe technique, and compared with that of pure YBCO thin film grown under the same growth conditions. The superconductivity of YBCO is found to be retained in the heterostructure. We observe a speeding up of the YBCO recombination dynamics in the superconducting state of the heterostructure, and attribute it to the presence of weak ferromagnetism at the BFO/YBCO interface as observed in magnetization data. An extension of the Rothwarf-Taylor model is used to fit the ultrafast dynamics of BFO/YBCO, that models an increased quasiparticle occupation of the ferromagnetic interfacial layer in the superconducting state of YBCO.

  6. Interfacial effects revealed by ultrafast relaxation dynamics in BiFeO 3 / YBa 2 Cu 3 O 7 bilayers

    KAUST Repository

    Springer, D.; Nair, Saritha K.; He, Mi; Lu, C. L.; Cheong, S. A.; Wu, Tao; Panagopoulos, C.; Chia, Elbert E. M.; Zhu, Jian-Xin

    2016-01-01

    The temperature dependence of the relaxation dynamics in the bilayer thin film heterostructure composed of multiferroic BiFeO3 (BFO) and superconducting YBa2Cu3O7 (YBCO) grown on a (001) SrTiO3 substrate is studied by a time-resolved pump-probe technique, and compared with that of pure YBCO thin film grown under the same growth conditions. The superconductivity of YBCO is found to be retained in the heterostructure. We observe a speeding up of the YBCO recombination dynamics in the superconducting state of the heterostructure, and attribute it to the presence of weak ferromagnetism at the BFO/YBCO interface as observed in magnetization data. An extension of the Rothwarf-Taylor model is used to fit the ultrafast dynamics of BFO/YBCO, that models an increased quasiparticle occupation of the ferromagnetic interfacial layer in the superconducting state of YBCO.

  7. (110)-Textured Ca-doped BiFeO_3 film on refined Pt(111) electrode layer on glass substrate at reduced temperature

    International Nuclear Information System (INIS)

    Chang, H.W.; Shen, C.Y.; Yuan, F.T.; Tien, S.H.; Lin, S.Y.; Chen, W.A.; Wang, C.R.; Tu, C.S.; Jen, S.U.

    2016-01-01

    Multiferroic and photovoltaic properties of polycrystalline Bi_0_._8_5Ca_0_._1_5FeO_3 (BCFO) film on refined Pt(111) electrode buffered glass substrate have been studied. Optimized Pt(111) electrode layer having large grain size and smooth morphology enables the development of highly (110)-textured BCFO film at a temperature as low as 450 °C. The prepared BCFO film has dense microstructure, fine grain size, and smooth surface morphology. Good ferroelectric properties with the remanent polarization (2P_r) of 108 μC/cm"2 and electrical coercive field of 405 kV/cm are achieved. Improved ferromagnetic properties with magnetization of 9.2 emu/cm"3 and coercivity of 1250 Oe are also attained. Significant PV properties with open-circuit photovoltage of 0.49 V and the short-circuit photocurrent of 67.4 μA/cm"2 at illumination intensity of 228 mW/cm"2 are observed, which are comparable to BCFO ceramics or BFO epitaxial films. - Highlights: • BCFO polycrystalline film with (110) texture is formed on Pt(111) electrode. • Pt(111) underlayer induces BCFO(110) film with fine grain and flat surface. • Good multiferroic and photovoltaic properties are achieved simultaneously. • Improved multiferroic and photovoltaic properties makes BCFO film a multifunctional material for advanced applications.

  8. Thin films

    International Nuclear Information System (INIS)

    Strongin, M.; Miller, D.L.

    1976-01-01

    This article reviews the phenomena that occur in films from the point of view of a solid state physicist. Films form the basis for many established and developing technologies. Metal layers have always been important for optical coatings and as protective coatings. In the most sophisticated cases, films and their interaction on silicon surfaces form the basis of modern electronic technology. Films of silicon, GaAs and composites of these materials promise to lead to practical photovoltaic devices

  9. Synchrotron X-ray studies of epitaxial ferroelectric thin films and nanostructures

    Science.gov (United States)

    Klug, Jeffrey A.

    The study of ferroelectric thin films is a field of considerable scientific and technological interest. In this dissertation synchrotron x-ray techniques were applied to examine the effects of lateral confinement and epitaxial strain in ferroelectric thin films and nanostructures. Three materials systems were investigated: laterally confined epitaxial BiFeO3 nanostructures on SrTiO3 (001), ultra-thin commensurate SrTiO 3 films on Si (001), and coherently strained films of BaTiO3 on DyScO3 (110). Epitaxial films of BiFeO3 were deposited by radio frequency magnetron sputtering on SrRuO3 coated SrTiO 3 (001) substrates. Laterally confined nanostructures were fabricated using focused ion-beam processing and subsequently characterized with focused beam x-ray nanodiffraction measurements with unprecedented spatial resolution. Results from a series of rectangular nanostructures with lateral dimensions between 500 nm and 1 mum and a comparably-sized region of the unpatterned BiFeO3 film revealed qualitatively similar distributions of local strain and lattice rotation with a 2-3 times larger magnitude of variation observed in those of the nanostructures compared to the unpatterned film. This indicates that lateral confinement leads to enhanced variation in the local strain and lattice rotation fields in epitaxial BiFeO3 nanostructures. A commensurate 2 nm thick film of SrTiO3 on Si was characterized by the x-ray standing wave (XSW) technique to determine the Sr and Ti cation positions in the strained unit cell in order to verify strain-induced ferroelectricity in SrTiO3/Si. A Si (004) XSW measurement at 10°C indicated that the average Ti displacement from the midpoint between Sr planes was consistent in magnitude to that predicted by a density functional theory (DFT) calculated ferroelectric structure. The Ti displacement determined from a 35°C measurement better matched a DFT-predicted nonpolar structure. The thin film extension of the XSW technique was employed to

  10. BiFeO3 Crystal Structure at Low Temperatures

    International Nuclear Information System (INIS)

    Palewicz, A.; Sosnowska, I.; Przenioslo, R.; Hewat, A.W.

    2010-01-01

    The crystal and magnetic structure of BiFeO 3 have been studied with the use of high resolution neutron diffraction between 5 K and 300 K. The atomic coordinates in BiFeO 3 are almost unchanged between 5 K and 300 K. (authors)

  11. 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

  12. 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.

  13. 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.

  14. Ultrathin limit and dead-layer effects in local polarization switching of BiFeO3

    NARCIS (Netherlands)

    Maksymovych, P.; Huijben, Mark; Pan, M.; Jesse, S.; Balke, N.; Chu, Y.H.; Chang, H.J.; Borisevich, A.Y.; Baddorf, A.P.; Rijnders, Augustinus J.H.M.; Blank, David H.A.; Ramesh, R.; Kalinin, S.V.

    2012-01-01

    Using piezoresponse force microscopy in an ultrahigh vacuum, polarization switching has been detected and quantified in epitaxial BiFeO3 films from 200 to about 4 unit cells thick. Local remnant piezoresponse was utilized to probe both ferroelectric properties and effects of imperfect electrical

  15. Thin Film & Deposition Systems (Windows)

    Data.gov (United States)

    Federal Laboratory Consortium — Coating Lab: Contains chambers for growing thin film window coatings. Plasma Applications Coating Lab: Contains chambers for growing thin film window coatings. Solar...

  16. 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.

  17. Tuning magnetic properties of magnetoelectric BiFeO 3-NiFe 2O 4 nanostructures

    Science.gov (United States)

    Crane, S. P.; Bihler, C.; Brandt, M. S.; Goennenwein, S. T. B.; Gajek, M.; Ramesh, R.

    2009-02-01

    Multifunctional thin film nanostructures containing soft magnetic materials such as nickel ferrite are interesting for potential applications in microwave signal processing because of the possibility to shrink the size of device architecture and limit device power consumption. An essential prerequisite to future applications of such a system is a firm understanding of its magnetic properties. We show that nanostructures composed of ferrimagnetic NiFe 2O 4 pillars in a multiferroic BiFeO 3 matrix can be tuned magnetically by altering the aspect ratio of the pillars by depositing films of varying thickness. Magnetic anisotropy is studied using ferromagnetic resonance, which shows that the uniaxial magnetic anisotropy in the growth direction changes sign upon increasing the film thickness. The magnitude of this anisotropy contribution can be explained via a combination of shape and magnetostatic effects, using the object-oriented micromagnetic framework (OOMMF). The key factors determining the magnetic properties of the films are shown to be the aspect ratio of individual pillars and magnetostatic interactions between neighboring pillars.

  18. Tuning magnetic properties of magnetoelectric BiFeO3-NiFe2O4 nanostructures

    International Nuclear Information System (INIS)

    Crane, S.P.; Bihler, C.; Brandt, M.S.; Goennenwein, S.T.B.; Gajek, M.; Ramesh, R.

    2009-01-01

    Multifunctional thin film nanostructures containing soft magnetic materials such as nickel ferrite are interesting for potential applications in microwave signal processing because of the possibility to shrink the size of device architecture and limit device power consumption. An essential prerequisite to future applications of such a system is a firm understanding of its magnetic properties. We show that nanostructures composed of ferrimagnetic NiFe 2 O 4 pillars in a multiferroic BiFeO 3 matrix can be tuned magnetically by altering the aspect ratio of the pillars by depositing films of varying thickness. Magnetic anisotropy is studied using ferromagnetic resonance, which shows that the uniaxial magnetic anisotropy in the growth direction changes sign upon increasing the film thickness. The magnitude of this anisotropy contribution can be explained via a combination of shape and magnetostatic effects, using the object-oriented micromagnetic framework (OOMMF). The key factors determining the magnetic properties of the films are shown to be the aspect ratio of individual pillars and magnetostatic interactions between neighboring pillars

  19. 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...

  20. Thin film tritium dosimetry

    Science.gov (United States)

    Moran, Paul R.

    1976-01-01

    The present invention provides a method for tritium dosimetry. A dosimeter comprising a thin film of a material having relatively sensitive RITAC-RITAP dosimetry properties is exposed to radiation from tritium, and after the dosimeter has been removed from the source of the radiation, the low energy electron dose deposited in the thin film is determined by radiation-induced, thermally-activated polarization dosimetry techniques.

  1. Measurement of transient atomic displacements in thin films with picosecond and femtometer resolution

    Directory of Open Access Journals (Sweden)

    M. Kozina

    2014-05-01

    Full Text Available We report measurements of the transient structural response of weakly photo-excited thin films of BiFeO3, Pb(Zr,TiO3, and Bi and time-scales for interfacial thermal transport. Utilizing picosecond x-ray diffraction at a 1.28 MHz repetition rate with time resolution extending down to 15 ps, transient changes in the diffraction angle are recorded. These changes are associated with photo-induced lattice strains within nanolayer thin films, resolved at the part-per-million level, corresponding to a shift in the scattering angle three orders of magnitude smaller than the rocking curve width and changes in the interlayer lattice spacing of fractions of a femtometer. The combination of high brightness, repetition rate, and stability of the synchrotron, in conjunction with high time resolution, represents a novel means to probe atomic-scale, near-equilibrium dynamics.

  2. Anharmonic phonons and magnons in BiFeO3

    Energy Technology Data Exchange (ETDEWEB)

    Delaire, Olivier A [ORNL; Ma, Jie [ORNL; Stone, Matthew B [ORNL; Huq, Ashfia [ORNL; Gout, Delphine J [ORNL; Brown, Craig [National Institute of Standards and Technology (NIST); Wang, Kefeng [Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing; Ren, Zhifeng [Boston College, Chestnut Hill

    2012-01-01

    The phonon density of states (DOS) and magnetic excitation spectrum of polycrystalline BiFeO3 were measured for temperatures 200 < T < 750K , using inelastic neutron scattering (INS). Our results indicate that the magnetic spectrum of BiFeO3 closely resembles that of similar Fe perovskites, such as LaFeO3, despite the cycloid modulation in BiFeO3. We do not find any evidence for a spin gap. A strong T-dependence of the phonon DOS was found, with a marked broadening of the whole spectrum, providing evidence of strong anharmonicity. This anharmonicity is corroborated by large amplitude motions of Bi and O ions observed with neutron diffraction. These results highlight the importance of spin-phonon coupling in this material.

  3. Domain wall conductivity in semiconducting hexagonal ferroelectric TbMnO3 thin films

    International Nuclear Information System (INIS)

    Kim, D J; Gruverman, A; Connell, J G; Seo, S S A

    2016-01-01

    Although enhanced conductivity of ferroelectric domain boundaries has been found in BiFeO 3 and Pb(Zr,Ti)O 3 films as well as hexagonal rare-earth manganite single crystals, the mechanism of the domain wall conductivity is still under debate. Using conductive atomic force microscopy, we observe enhanced conductance at the electrically-neutral domain walls in semiconducting hexagonal ferroelectric TbMnO 3 thin films where the structure and polarization direction are strongly constrained along the c-axis. This result indicates that domain wall conductivity in ferroelectric rare-earth manganites is not limited to charged domain walls. We show that the observed conductivity in the TbMnO 3 films is governed by a single conduction mechanism, namely, the back-to-back Schottky diodes tuned by the segregation of defects. (paper)

  4. Ferroelectric properties of PZT/BFO multilayer thin films prepared using the sol-gel method.

    Science.gov (United States)

    Jo, Seo-Hyeon; Lee, Sung-Gap; Lee, Young-Hie

    2012-01-05

    In this study, Pb(Zr0.52Ti0.48)O3/BiFeO3 [PZT/BFO] multilayer thin films were fabricated using the spin-coating method on a Pt(200 nm)/Ti(10 nm)/SiO2(100 nm)/p-Si(100) substrate alternately using BFO and PZT metal alkoxide solutions. The coating-and-heating procedure was repeated several times to form the multilayer thin films. All PZT/BFO multilayer thin films show a void-free, uniform grain structure without the presence of rosette structures. The relative dielectric constant and dielectric loss of the six-coated PZT/BFO [PZT/BFO-6] thin film were approximately 405 and 0.03%, respectively. As the number of coatings increased, the remanent polarization and coercive field increased. The values for the BFO-6 multilayer thin film were 41.3 C/cm2 and 15.1 MV/cm, respectively. The leakage current density of the BFO-6 multilayer thin film at 5 V was 2.52 × 10-7 A/cm2.

  5. Thin films and nanomaterials

    International Nuclear Information System (INIS)

    Jayakumar, S.; Kannan, M.D.; Prasanna, S.

    2012-01-01

    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

  6. Synthesis of BiFeO 3 by carbonate precipitation

    Indian Academy of Sciences (India)

    Magnetoelectric multiferroic BiFeO3 (BFO) was synthesized by a simple carbonate precipitation technique of metal nitrate solutions. X-ray powder diffraction and thermo-gravimetric analysis (TGA) revealed that the precipitate consists of an intimate mixture of crystalline bismuth carbonate and an amorphous hydroxide of ...

  7. Thin Film Microbatteries

    International Nuclear Information System (INIS)

    Dudney, Nancy J.

    2008-01-01

    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 cm 2 . 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. Optical thin film deposition

    International Nuclear Information System (INIS)

    Macleod, H.A.

    1979-01-01

    The potential usefulness in the production of optical thin-film coatings of some of the processes for thin film deposition which can be classified under the heading of ion-assisted techniques is examined. Thermal evaporation is the process which is virtually universally used for this purpose and which has been developed to a stage where performance is in almost all respects high. Areas where further improvements would be of value, and the possibility that ion-assisted deposition might lead to such improvements, are discussed. (author)

  9. Thin Film Photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Zweibel, K.

    1998-11-19

    The motivation to develop thin film technologies dates back to the inception of photovoltaics. It is an idea based on achieving truly low-cost photovoltaics appropriate for mass production and energy significant markets. The key to the idea is the use of pennies worth of active materials. Since sunlight carries relatively little energy in comparison with combustion-based energy sources, photovoltaic (PV) modules must be cheap to produce energy that can be competitive. Thin films are presumed to be the answer to that low-cost requirement. But how cheap do they have to be? The following is an oversimplified analysis that allows some insight into this question.

  10. 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.

  11. 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.

  12. NMR characterization of thin films

    Science.gov (United States)

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

    2010-06-15

    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.

  13. 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.

  14. 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.

  15. 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.

  16. Microstructure, vertical strain control and tunable functionalities in self-assembled, vertically aligned nanocomposite thin films

    International Nuclear Information System (INIS)

    Chen, Aiping; Bi, Zhenxing; Jia, Quanxi; MacManus-Driscoll, Judith L.; Wang, Haiyan

    2013-01-01

    Vertically aligned nanocomposite (VAN) oxide thin films have recently stimulated a significant amount of research interest owing to their novel architecture, vertical interfacial strain control and tunable material functionalities. In this work, the growth mechanisms of VAN thin films have been investigated by varying the composite material system, the ratio of the two constituent phases, and the thin film growth conditions including deposition temperature and oxygen pressure as well as growth rate. It has been shown that thermodynamic parameters, elastic and interfacial energies and the multiple phase ratio play dominant roles in the resulting microstructure. In addition, vertical interfacial strain has been observed in BiFeO 3 (BFO)- and La 0.7 Sr 0.3 MnO 3 (LSMO)-based VAN thin film systems; the vertical strain could be tuned by the growth parameters and selection of a suitable secondary phase. The tunability of physical properties such as dielectric loss in BFO:Sm 2 O 3 VAN and low-field magnetoresistance in LSMO-based VAN systems has been demonstrated. The enhancement and tunability of those physical properties have been attributed to the unique VAN architecture and vertical strain control. These results suggest that VAN architecture with novel microstructure and unique vertical strain tuning could provide a general route for tailoring and manipulating the functionalities of oxide thin films

  17. Magnetic hysteresis of cerium doped bismuth ferrite thin films

    International Nuclear Information System (INIS)

    Gupta, Surbhi; Tomar, Monika; Gupta, Vinay

    2015-01-01

    The influence of Cerium doping on the structural and magnetic properties of BiFeO 3 thin films have been investigated. Rietveld refinement of X-ray diffraction data and successive de-convolution of Raman scattering spectra of Bi 1−x Ce x FeO 3 (BCFO) thin films with x=0–0.20 reflect the single phase rhombohedral (R3c) formation for x<0.08, whereas concentration-driven gradual structural phase transition from rhombohedral (R3c) to partial tetragonal (P4mm) phase follows for x≥0.08. All low wavenumber Raman modes (<300 cm −1 ) showed a noticeable shift towards higher wavenumber with increase in doping concentration, except Raman E-1 mode (71 cm −1 ), shows a minor shift. Sudden evolution of Raman mode at 668 cm −1 , manifested as A 1 -tetragonal mode, accompanied by the shift to higher wavenumber with increase in doping concentration (x) affirm partial structural phase transition. Anomalous wasp waist shaped (M–H) hysteresis curves with improved saturation magnetization (M s ) for BCFO thin films is attributed to antiferromagnetic interaction/hybridization between Ce 4f and Fe 3d electronic states. The contribution of both hard and soft phase to the total coercivity is calculated. Polycrystalline Bi 0.88 Ce 0.12 FeO 3 thin film found to exhibit better magnetic properties with M s =15.9 emu/g without any impure phase. - Highlights: • Synthesis of single phase Bi 1−x Ce x FeO 3 thin films with (x=0–0.2) on cost effective corning glass and silicon substrates using CSD technique. • Structural modification studies using Rietveld refinement of XRD and de-convolution of Raman spectra revealed partial phase transition from rhombohedral (R3c) to tetragonal (P4mm) phase. • Possible reasons for origin of pinched magnetic behavior of BCFO thin films are identified. • Contribution of both hard and soft magnetic phase in coercivity of BCFO thin films is calculated and practical applications of such materials exhibiting pinching behavior are conferred

  18. Optical and electrical properties of thin films of bismuth ferric oxide

    International Nuclear Information System (INIS)

    Cardona R, D.

    2014-01-01

    The bismuth ferric oxide (BFO) has caused great attention in recent years because of their multi ferric properties, making it very attractive for different technological applications. In this paper simultaneous ablation of two white (Bi and Fe 2 O 3 ) was used in a reactive atmosphere (containing oxygen) to deposit thin films of BFO. The composition of the films is changed by controlling the plasma parameters such as the average kinetic energy of the ions (E p) and the plasma density (Np). The effects caused by excess of Bi and Fe in atomic structure and the optical and electrical properties of the films BiFeO 3 in terms of plasma parameters were studied. The X-ray diffraction patterns of BFO samples with excess of bismuth above 2% at. They exhibited small changes in structure leading to improved levels of leakage currents compared to levels of the film with a stoichiometry close to BiFeO 3 composition. These samples showed a secondary phase (Bi 2 5FeO 4 0 selenite type) that led to the increase in the values of band gap and resistivity as well as the improvement of the piezoelectric properties. On the other hand, the films with iron excess showed as secondary phase compounds of iron oxide (α - γ-Fe 2 O 3 ) that caused increments in the conductivity and decrease in the values of band gap. The results are discussed in terms of the excesses of Bi and Fe which were correlated with the plasma parameters. (Author)

  19. Superconducting oxypnictide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Reisner, Andreas; Kidszun, Martin; Reich, Elke; Holzapfel, Bernhard; Schultz, Ludwig; Haindl, Silvia [IFW Dresden, Institute of Metallic Materials (Germany); Thersleff, Thomas [Uppsala University, Angstrom Laboratory (Sweden)

    2012-07-01

    We present an overview on the oxypnictide thin film preparation. So far, only LaAlO{sub 3} (001) single crystalline substrates provided a successful growth using pulsed laser deposition in combination with a post annealing process. Further experiments on the in-situ deposition will be reported. The structure of the films was investigated by X-ray diffractometry and transmission electron microscopy. Transport properties were measured with different applied fields to obtain a magnetic phase diagram for this new type of superconductor.

  20. Mechanics of Thin Films

    Science.gov (United States)

    1992-02-06

    and the second geometry was that of squat cylinders (diameter 6.4 mm, height 6.4 mm). These two geometries were tested in thermal shock tests, and a...milder [13]. More recently, Lau, Rahman and stressa nce ntrati, tha n films of lmalla rat ve spc Delale calculated the free edge singularity for stress...thickness of 3 mm); the second geometry was that As an example of the shielding effect of thin films, we of squat cylinders (diameter 6.4 mm, height 6.4

  1. Refractive index dispersion of swift heavy ion irradiated BFO thin films using Surface Plasmon Resonance technique

    Science.gov (United States)

    Paliwal, Ayushi; Sharma, Savita; Tomar, Monika; Singh, Fouran; Gupta, Vinay

    2016-07-01

    Swift heavy ion irradiation (SHI) is an effective technique to induce defects for possible modifications in the material properties. There is growing interest in studying the optical properties of multiferroic BiFeO3 (BFO) thin films for optoelectronic applications. In the present work, BFO thin films were prepared by sol-gel spin coating technique and were irradiated using the 15 UD Pelletron accelerator with 100 MeV Au9+ ions at a fluence of 1 × 1012 ions cm-2. The as-grown films became rough and porous on ion irradiation. Surface Plasmon Resonance (SPR) technique has been identified as a highly sensitive and powerful technique for studying the optical properties of a dielectric material. Optical properties of BFO thin films, before and after irradiation were studied using SPR technique in Otto configuration. Refractive index is found to be decreasing from 2.27 to 2.14 on ion irradiation at a wavelength of 633 nm. Refractive index dispersion of BFO thin film (from 405 nm to 633 nm) before and after ion radiation was examined.

  2. 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.

  3. Perovskite type nanopowders and thin films obtained by chemical methods

    Directory of Open Access Journals (Sweden)

    Viktor Fruth

    2010-09-01

    Full Text Available The review presents the contribution of the authors, to the preparation of two types of perovskites, namely BiFeO3 and LaCoO3, by innovative methods. The studied perovskites were obtained as powders, films and sintered bodies. Their complex structural and morphological characterization is also presented. The obtained results have underlined the important influence of the method of preparation on the properties of the synthesized perovskites.

  4. 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.

  5. Room temperature ferromagnetism with large magnetic moment at low field in rare-earth-doped BiFeO₃ thin films.

    Science.gov (United States)

    Kim, Tae-Young; Hong, Nguyen Hoa; Sugawara, T; Raghavender, A T; Kurisu, M

    2013-05-22

    Thin films of rare earth (RE)-doped BiFeO3 (where RE=Sm, Ho, Pr and Nd) were grown on LaAlO3 substrates by using the pulsed laser deposition technique. All the films show a single phase of rhombohedral structure with space group R3c. The saturated magnetization in the Ho- and Sm-doped films is much larger than the values reported in the literature, and is observed at quite a low field of 0.2 T. For Ho and Sm doping, the magnetization increases as the film becomes thinner, suggesting that the observed magnetism is mostly due to a surface effect. In the case of Nd doping, even though the thin film has a large magnetic moment, the mechanism seems to be different.

  6. Electric control of magnon frequencies and magnetic moment of bismuth ferrite thin films at room temperature.

    Science.gov (United States)

    Kumar, Ashok; Scott, J F; Katiyar, R S

    2011-08-08

    Here, we report the tuning of room-temperature magnon frequencies from 473 GHz to 402 GHz (14%) and magnetic moment from 4 to 18 emu∕cm(3) at 100 Oe under the application of external electric fields (E) across interdigital electrodes in BiFeO(3) (BFO) thin films. A decrease in magnon frequencies and increase in phonon frequencies were observed with Magnon and phonon Raman intensities are asymmetric with polarity, decreasing with positive E (+E) and increasing with negative E (-E) where polarity is with respect to in-plane polarization P. The magnetoelectric coupling (α) is proved to be linear and a rather isotropic α = 8.5 × 10(-12) sm(-1).

  7. Thin films for precision optics

    International Nuclear Information System (INIS)

    Araujo, J.F.; Maurici, N.; Castro, J.C. de

    1983-01-01

    The technology of producing dielectric and/or metallic thin films for high precision optical components is discussed. Computer programs were developed in order to calculate and register, graphically, reflectance and transmittance spectra of multi-layer films. The technology of vacuum evaporation of several materials was implemented in our thin-films laboratory; various films for optics were then developed. The possibility of first calculate film characteristics and then produce the film is of great advantage since it reduces the time required to produce a new type of film and also reduces the cost of the project. (C.L.B.) [pt

  8. Microstructure of Thin Films

    Science.gov (United States)

    1990-02-07

    Proceedings, Thin film Technologies II, 652, 256-263, (1986) B. Schmitt, J.P. Borgogno, G. Albrand and E. Pelletier, "In situ and air index measurements...34 SPIE Proceedings, "Optical Components and Systems", 805, 128 (1987) 11 B. Schmitt, J.P. Borgogno, G. Albrand and E. Pelletier. "In situ and air index...aT , m..a, lot,, o ,,f,02,d I4 k -1-1..... autocovariance lengths, less than 0.5 um, indicate that , 514n, ob0 o p’,Ofclllc....,,o,,oy0,1- agua sblrt

  9. Multiferroic BiFeO3-BiMnO3 Nanocheckerboard From First Principles

    OpenAIRE

    Palova, L.; Chandra, P.; Rabe, K. M.

    2010-01-01

    We present a first principles study of an unusual heterostructure, an atomic-scale checkerboard of BiFeO3-BiMnO3, and compare its properties to the two bulk constituent materials, BiFeO3 and BiMnO3. The "nanocheckerboard" is found to have a multiferroic ground state with the desired properties of each constituent: polar and ferrimagnetic due to BiFeO3 and BiMnO3, respectively. The effect of B-site cation ordering on magnetic ordering in the BiFeO3-BiMnO3 system is studied. The checkerboard ge...

  10. Host thin films incorporating nanoparticles

    Science.gov (United States)

    Qureshi, Uzma

    The focus of this research project was the investigation of the functional properties of thin films that incorporate a secondary nanoparticulate phase. In particular to assess if the secondary nanoparticulate material enhanced a functional property of the coating on glass. In order to achieve this, new thin film deposition methods were developed, namely use of nanopowder precursors, an aerosol assisted transport technique and an aerosol into atmospheric pressure chemical vapour deposition system. Aerosol assisted chemical vapour deposition (AACVD) was used to deposit 8 series of thin films on glass. Five different nanoparticles silver, gold, ceria, tungsten oxide and zinc oxide were tested and shown to successfully deposit thin films incorporating nanoparticles within a host matrix. Silver nanoparticles were synthesised and doped within a titania film by AACVD. This improved solar control properties. A unique aerosol assisted chemical vapour deposition (AACVD) into atmospheric pressure chemical vapour deposition (APCVD) system was used to deposit films of Au nanoparticles and thin films of gold nanoparticles incorporated within a host titania matrix. Incorporation of high refractive index contrast metal oxide particles within a host film altered the film colour. The key goal was to test the potential of nanopowder forms and transfer the suspended nanopowder via an aerosol to a substrate in order to deposit a thin film. Discrete tungsten oxide nanoparticles or ceria nanoparticles within a titanium dioxide thin film enhanced the self-cleaning and photo-induced super-hydrophilicity. The nanopowder precursor study was extended by deposition of zinc oxide thin films incorporating Au nanoparticles and also ZnO films deposited from a ZnO nanopowder precursor. Incorporation of Au nanoparticles within a VO: host matrix improved the thermochromic response, optical and colour properties. Composite VC/TiC and Au nanoparticle/V02/Ti02 thin films displayed three useful

  11. Thin-film photovoltaic technology

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharya, R.N. [National Renewable Energy Laboratory, Golden, CO (United States)

    2010-07-01

    The high material and processing costs associated with single-crystal and polycrystalline silicon wafers that are commonly used in photovoltaic cells render these modules expensive. This presentation described thin-film solar cell technology as a promising alternative to silicon solar cell technology. Cadmium telluride (CdTe) thin films along with copper, indium, gallium, and selenium (CIGS) thin films have become the leaders in this field. Their large optical absorption coefficient can be attributed to a direct energy gap that allows the use of thin layers (1-2 {mu}m) of active material. The efficiency of thin-film solar cell devices based on CIGS is 20 per cent, compared to 16.7 per cent for thin-film solar cell devices based on CdTe. IBM recently reported an efficiency of 9.7 per cent for a new type of inorganic thin-film solar cell based on a Cu{sub 2}ZnSn(S, Se){sub 4} compound. The efficiency of an organic thin-film solar cell is 7.9 per cent. This presentation included a graph of PV device efficiencies and discussed technological advances in non-vacuum deposited, CIGS-based thin-film solar cells. 1 fig.

  12. Unidirectional THz radiation propagation in BiFeO3

    Science.gov (United States)

    Room, Toomas

    The mutual coupling between magnetism and electricity present in many multiferroic materials permit the magnetic control of the electric polarization and the electric control of the magnetization. These static magnetoelectric (ME) effects are of enormous interest: The ability to write a magnetic state current-free by an electric voltage would provide a huge technological advantage. However, ME coupling changes the low energy electrodynamics of these materials in unprecedented way - optical ME effects give rise to unidirectional light propagation as recently observed in low-temperature multiferroics. The transparent direction can be switched with dc magnetic or electric field, thus opening up new possibilities to manipulate the propagation of electromagnetic waves in multiferroic materials. We studied the unidirectional transmission of THz radiation in BiFeO3 crystals, the unique multiferroic compound offering a real potential for room temperature applications. The electrodynamics of BiFeO3 at 1THz and below is dominated by the spin wave modes of cycloidal spin order. We found that the optical magnetoelectric effect generated by spin waves in BiFeO3 is robust enough to cause considerable nonreciprocal directional dichroism in the GHz-THz range even at room temperature. The supporting theory attributes the observed unidirectional transmission to the spin-current-driven dynamic ME effect. Our work demonstrates that the nonreciprocal directional dichroism spectra of low energy excitations and their theoretical analysis provide microscopic model of ME couplings in multiferroic materials. Recent THz spectroscopy studies of multiferroic materials are an important step toward the realization of optical diodes, devices which transmit light in one but not in the opposite direction.

  13. Stress induced enhanced polarization in multilayer BiFeO3/BaTiO3 structure with improved energy storage properties

    Directory of Open Access Journals (Sweden)

    Savita Sharma

    2015-10-01

    Full Text Available Present work reports the fabrication of a multilayer (5-layer structure of BiFeO3(BFO/BaTiO3(BTO using spin-coating technique. The crystallographic structure, surface morphology and ferroelectric behavior of multilayer structure in metal-ferroelectric-metal capacitor have been studied. Le-Bail refinement of X-ray diffraction data revealed the formation of polycrystalline pure perovskite phase with induced stress. The values of remnant (Pr and saturation polarization (Ps for BFO/BTO multilayer structure are found to be 38.14 μC/cm2 and 71.54 μC/cm2 respectively, which are much higher than the corresponding values reported for bare BFO thin film. A large value of dielectric constant of 187 has been obtained for multilayer structure with a low leakage current density of 1.09 × 10−7 A/cm2 at applied bias of 10 V. The BFO/BTO multilayer structure favors the enhanced energy storage capacity as compared to bare BFO thin film with improved values of energy-density and charge-discharge efficiency as 121 mJ/cm3 and 59% respectively, suggesting futuristic energy storage applications.

  14. Electronic conduction in doped multiferroic BiFeO3

    Science.gov (United States)

    Yang, Chan-Ho; Seidel, Jan; Kim, Sang-Yong; Gajek, M.; Yu, P.; Holcomb, M. B.; Martin, L. W.; Ramesh, R.; Chu, Y. H.

    2009-03-01

    Competition between multiple ground states, that are energetically similar, plays a key role in many interesting material properties and physical phenomena as for example in high-Tc superconductors (electron kinetic energy vs. electron-electron repulsion), colossal magnetoresistance (metallic state vs. charge ordered insulating state), and magnetically frustrated systems (spin-spin interactions). We are exploring the idea of similar competing phenomena in doped multiferroics by control of band-filling. In this paper we present systematic investigations of divalent Ca doping of ferroelectric BiFeO3 in terms of structural and electronic conduction properties as well as diffusion properties of oxygen vacancies.

  15. Polymer Thin Film Stabilization.

    Science.gov (United States)

    Costa, A. C.; Oslanec, R.; Composto, R. J.; Vlcek, P.

    1998-03-01

    We study the dewetting dynamics of thin polystyrene (PS) films deposited on silicon oxide surfaces using optical (OM) and atomic force (AFM) microscopes. Quantitative analysis of the hole diameter as a function of annealing time at 175^oC shows that blending poly(styrene-block-methyl-methacrylate) (PS-b-PMMA) with PS acts to dramatically slow down the dewetting rate and even stops holes growth before they impinge. AFM studies show that the hole floor is smooth for a pure PS film but contains residual polymer for the blend. At 5% vol., a PS-b-PMMA with high molar mass and low PMMA is a more effective stabilizing agent than a low molar mass/high PMMA additive. The optimum copolymer concentration is 3% vol. beyond which film stability doesn't improve. Although dewetting is slowed down relative to pure PS, PS/PS-b-PMMA bilayers dewet at a faster rate than blends having the same overall additive concentration.

  16. Local Probing of Magnetoelectric Coupling and Magnetoelastic Control of Switching in BiFeO3-CoFe2O4 Thin-Film Nanocomposite

    Science.gov (United States)

    2013-07-25

    at remanent state (Fig. 4(d)). The obtained ME coefficient (the highest value we measure is 102 mV/ cm/Oe) and is comparable to that of bulk PZT -CFO...For a large field (H > Hc), a mag- netostrictive strain (k) must be already saturated and the ME coefficient estimated (Fig. 4) should be nearly...zero at high field (as a function of piezomagnetic coefficient (dk=dH), leading to a maximum in the ME response near Hc. That this is not observed can be

  17. Thin films: Past, present, future

    Energy Technology Data Exchange (ETDEWEB)

    Zweibel, K

    1995-04-01

    This report describes the characteristics of the thin film photovoltaic modules necessary for an acceptable rate of return for rural areas and underdeveloped countries. The topics of the paper include a development of goals of cost and performance for an acceptable PV system, a review of current technologies for meeting these goals, issues and opportunities in thin film technologies.

  18. 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

  19. Thin-film solar cells

    International Nuclear Information System (INIS)

    Aberle, Armin G.

    2009-01-01

    The rapid progress that is being made with inorganic thin-film photovoltaic (PV) technologies, both in the laboratory and in industry, is reviewed. While amorphous silicon based PV modules have been around for more than 20 years, recent industrial developments include the first polycrystalline silicon thin-film solar cells on glass and the first tandem solar cells based on stacks of amorphous and microcrystalline silicon films ('micromorph cells'). Significant thin-film PV production levels are also being set up for cadmium telluride and copper indium diselenide.

  20. modified BiFeO3–BaTiO3

    Indian Academy of Sciences (India)

    based perovskite structures lead- free BiFeO3–BaTiO3 solid solutions are popularly studied due to the high Curie temperature (TC). It was reported that the BiFeO3–BaTiO3 system possessed high piezoelectric. ∗. Author for correspondence ...

  1. Characterization of organic thin films

    CERN Document Server

    Ulman, Abraham; Evans, Charles A

    2009-01-01

    Thin films based upon organic materials are at the heart of much of the revolution in modern technology, from advanced electronics, to optics to sensors to biomedical engineering. This volume in the Materials Characterization series introduces the major common types of analysis used in characterizing of thin films and the various appropriate characterization technologies for each. Materials such as Langmuir-Blodgett films and self-assembled monolayers are first introduced, followed by analysis of surface properties and the various characterization technologies used for such. Readers will find detailed information on: -Various spectroscopic approaches to characterization of organic thin films, including infrared spectroscopy and Raman spectroscopy -X-Ray diffraction techniques, High Resolution EELS studies, and X-Ray Photoelectron Spectroscopy -Concise Summaries of major characterization technologies for organic thin films, including Auger Electron Spectroscopy, Dynamic Secondary Ion Mass Spectrometry, and Tra...

  2. Interfaces and thin films physics

    International Nuclear Information System (INIS)

    Equer, B.

    1988-01-01

    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 [fr

  3. The microscopic model of BiFeO3

    Science.gov (United States)

    Fishman, R. S.

    2018-05-01

    Many years and great effort have been spent constructing the microscopic model for the room temperature multiferroic BiFeO3. However, earlier models implicitly assumed that the cycloidal wavevector q was confined to one of the three-fold symmetric axes in the hexagonal plane normal to the electric polarization. Because recent measurements indicate that q can be rotated by a magnetic field, it is essential to properly treat the anisotropy that confines q at low fields. We propose that the anisotropy energy -K3S6sin6 θ cos 6 ϕ confines the wavevectors q to the three-fold axis ϕ = 0 and ± 2 π / 3 within the hexagonal plane with θ = π / 2 .

  4. Thin-Film Power Transformers

    Science.gov (United States)

    Katti, Romney R.

    1995-01-01

    Transformer core made of thin layers of insulating material interspersed with thin layers of ferromagnetic material. Flux-linking conductors made of thinner nonferromagnetic-conductor/insulator multilayers wrapped around core. Transformers have geometric features finer than those of transformers made in customary way by machining and mechanical pressing. In addition, some thin-film materials exhibit magnetic-flux-carrying capabilities superior to those of customary bulk transformer materials. Suitable for low-cost, high-yield mass production.

  5. 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.

  6. Superconducting thin films

    International Nuclear Information System (INIS)

    Hebard, A.F.; Vandenberg, J.M.

    1982-01-01

    This invention relates to granular metal and metal oxide superconducting films formed by ion beam sputter deposition. Illustratively, the films comprise irregularly shaped, randomly oriented, small lead grains interspersed in an insulating lead oxide matrix. The films are hillock-resistant when subjected to thermal cycling and exhibit unusual josephson-type switching characteristics. Depending on the oxygen content, a film may behave in a manner similar to that of a plurality of series connected josephson junctions, or the film may have a voltage difference in a direction parallel to a major surface of the film that is capable of being switched from zero voltage difference to a finite voltage difference in response to a current larger than the critical current

  7. Photocatalytic and Magnetic Behaviors Observed in BiFeO3 Nanofibers by Electrospinning

    Directory of Open Access Journals (Sweden)

    Xuehui Zhang

    2013-01-01

    Full Text Available Perovskite-type BiFeO3 nanofibers with wave nodes-like morphology were prepared by electrospinning. The nanofibers show a highly enhanced visible-light-active photocatalytic property. The results also showed that the diameter could affect the band gap and photocatalytic performances of nanofibers. Additionally, weak ferromagnetic behaviors can be observed at room temperature, which should be correlated to the size-confinement effect on the magnetic ordering of BiFeO3 structure.

  8. Beryllium thin films for resistor applications

    Science.gov (United States)

    Fiet, O.

    1972-01-01

    Beryllium thin films have a protective oxidation resistant property at high temperature and high recrystallization temperature. However, the experimental film has very low temperature coefficient of resistance.

  9. Fabrication, Characterization, Properties, and Applications of Low-Dimensional BiFeO3 Nanostructures

    Directory of Open Access Journals (Sweden)

    Heng Wu

    2014-01-01

    Full Text Available Low-dimensional BiFeO3 nanostructures (e.g., nanocrystals, nanowires, nanotubes, and nanoislands have received considerable attention due to their novel size-dependent properties and outstanding multiferroic properties at room temperature. In recent years, much progress has been made both in fabrications and (microstructural, electrical, and magnetic in characterizations of BiFeO3 low-dimensional nanostructures. An overview of the state of art in BiFeO3 low-dimensional nanostructures is presented. First, we review the fabrications of high-quality BiFeO3 low-dimensional nanostructures via a variety of techniques, and then the structural characterizations and physical properties of the BiFeO3 low-dimensional nanostructures are summarized. Their potential applications in the next-generation magnetoelectric random access memories and photovoltaic devices are also discussed. Finally, we conclude this review by providing our perspectives to the future researches of BiFeO3 low-dimensional nanostructures and some key problems are also outlined.

  10. Semiconductor-nanocrystal/conjugated polymer thin films

    Science.gov (United States)

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

    2014-06-17

    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.

  11. Preparation of thin vyns films

    International Nuclear Information System (INIS)

    Blanc, R.; Chedin, P.; Gizon, A.

    1965-01-01

    The fabrication of thin films of VYNS resin (copolymer of chloride and vinyl acetate) of superficial density from 3 to 50 μg/cm 2 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 [fr

  12. Nanocrystal thin film fabrication methods and apparatus

    Science.gov (United States)

    Kagan, Cherie R.; Kim, David K.; Choi, Ji-Hyuk; Lai, Yuming

    2018-01-09

    Nanocrystal thin film devices and methods for fabricating nanocrystal thin film devices are disclosed. The nanocrystal thin films are diffused with a dopant such as Indium, Potassium, Tin, etc. to reduce surface states. The thin film devices may be exposed to air during a portion of the fabrication. This enables fabrication of nanocrystal-based devices using a wider range of techniques such as photolithography and photolithographic patterning in an air environment.

  13. Enhancement of switching speed of BiFeO3 capacitors by magnetic fields

    Directory of Open Access Journals (Sweden)

    E. J. Guo

    2014-09-01

    Full Text Available The effect of a magnetic field on the ferroelectric switching kinetics of BiFeO3 (BFO capacitors with La0.8Ca0.2MnO3 (LCMO bottom electrode and Pt top contact has been investigated. We find a strong dependence of the remnant polarization and coercive field on the magnetic field. The switching time can be systematically tuned by magnetic field and reaches a tenfold reduction around the Curie temperature of LCMO at 4 T. We attribute this behavior to the splitting of the voltage drops across the BFO film and the LCMO bottom electrode, which can be strongly influenced by an external magnetic field due to the magnetoresistance. Further experiments on the BFO capacitors with SrRuO3 bottom electrodes show little magnetic field dependence of ferroelectric switching confirming our interpretation. Our results provide an efficient route to control the ferroelectric switching speed through the magnetic field, implying potential application in multifunctional devices.

  14. Enhanced photocatalytic property of BiFeO_3/N-doped graphene composites and mechanism insight

    International Nuclear Information System (INIS)

    Li, Pai; Li, Lei; Xu, Maji; Chen, Qiang; He, Yunbin

    2017-01-01

    Highlights: • A hydrothermal process was used to prepare BiFeO_3/N-doped graphene composites. • BiFeO_3/N-doped graphene exhibits superior photocatalytic activity and stability. • The energy band of BiFeO_3 bends downward by ∼1.0 eV at the composite interface. • Downward band bending leads to rapid electron transfer at the composite interface. • Holes and ·OH are predominant active species in the photo-degradation process. - Abstract: A series of BiFeO_3/(N-doped) graphene composites are prepared by a facile hydrothermal method. BiFeO_3/N-doped graphene shows photocatalytic performance superior to that of BiFeO_3/graphene and pristine BiFeO_3. The enhanced photo-degradation performance of BiFeO_3/N-doped graphene are mainly attributable to the improved light absorbance of the composite, abundant active adsorption sites and high electrical charge mobility of N-doped graphene, and the downward band bending of BiFeO_3 at the composite interface. In particular, X-ray photoelectron spectroscopy analyses reveal that the electron energy band of BiFeO_3 is downward bent by 1.0 eV at the interface of BiFeO_3/N-doped graphene, because of different work functions of both materials. This downward band bending facilitates the transfer of photogenerated electrons from BiFeO_3 to N-doped graphene and prompts the separation of photo-generated electron-hole pairs, leading eventually to the enhanced photocatalytic performance.

  15. Synthesis, microstructure and properties of BiFeO3-based multiferroic materials: A review

    Directory of Open Access Journals (Sweden)

    Bernardo, M. S.

    2014-02-01

    Full Text Available BiFeO3-based materials are currently one of the most studied multiferroics due to their possible applications at room temperature. However, among the large number of published papers there is much controversy. For example, possibility of synthesizing a pure BiFeO3 phase is still source of discussion in literature. Not even the nature of the binary Bi2O3-Fe2O3 diagram has been clarified yet. The difficulty in controlling the formation of parasite phases reaches the consolidation step. Accordingly, the sintering conditions must be carefully determined both to get dense materials and to avoid bismuth ferrite decomposition. However, the precise conditions to attain dense bismuth ferrite materials are frequently contradictory among different works. As a consequence, the reported properties habitually result opposed and highly irreproducible hampering the preparation of BiFeO3 materials suitable for practical applications. In this context, the purpose of the present review is to summarize the main researches regarding BiFeO3 synthesis, microstructure and properties in order to provide an easier understanding of these materials.Los materiales basados en BiFeO3 son en la actualidad uno de los multiferroicos más estudiados debido a sus posibles aplicaciones a temperatura ambiente. Sin embargo, entre la multitud de trabajos publicados referentes a estos materiales existe mucha controversia. Por ejemplo, la posibilidad de sintetizar una fase BiFeO3 pura es aún objeto de discusión en la bibliografía y la naturaleza de los diagramas de fases del sistema Bi2O3-Fe2O3 aún no está clara. La dificultad para controlar las fases parásitas se extiende al proceso de consolidación por lo que las condiciones de sinterización deben ser cuidadosamente controladas para obtener materiales densos y al mismo tiempo evitar la descomposición de la ferrita. No obstante, las condiciones precisas para obtener materiales densos de BiFeO3 son frecuentemente contradictorias entre los distintos trabajos. Como consecuencia, las propiedades descritas son a menudo discordantes y poco reproducibles impidiendo la preparación de materiales de BiFeO3 adecuados para sus aplicaciones prácticas. En este contexto, el propósito de esta revisión es resumir las principales investigaciones en torno a la síntesis, microestructura y propiedades de los materiales de BiFeO3 facilitando así la comprensión de los mismos.

  16. Containerless solidification of BiFeO3 oxide under microgravity

    Science.gov (United States)

    Yu, Jianding; Arai, Yasutomo; Koshikawa, Naokiyo; Ishikawa, Takehito; Yoda, Shinichi

    1999-07-01

    Containerless solidification of BiFeO3 oxide has been carried out under microgravity with Electrostatic Levitation Furnace (ELF) aboard on the sounding rocket (TR-IA). It is a first containerless experiment using ELF under microgravity for studying the solidification of oxide insulator material. Spherical BiFeO3 sample with diameter of 5mm was heated by two lasers in oxygen and nitrogen mixing atmosphere, and the sample position by electrostatic force under pinpoint model and free drift model. In order to compare the solidification behavior in microgravity with on ground, solidification experiments of BiFeO3 in crucible and drop tube were carried out. In crucible experiment, it was very difficult to get single BiFeO3 phase, because segregation of Fe2O3 occured very fast and easily. In drop tube experiment, fine homogeneous BiFeO3 microstructure was obtained in a droplet about 300 μm. It implies that containerless processing can promote the phase selection in solidification. In microgravity experiment, because the heating temperature was lower than that of estimated, the sample was heated into Fe2O3+liquid phase region. Fe2O3 single crystal grew on the surface of the spherical sample, whose sample was clearly different from that observed in ground experiments.

  17. 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...

  18. Review of thin film superconductivity

    International Nuclear Information System (INIS)

    Kihlstrom, K.E.

    1989-01-01

    Advances in thin film superconductivity are critical to the success of many proposed applications. The authors review several of the prominent techniques currently used to produce thin films of the high temperature superconductors including electron beam co-deposition, sputtering (both multiple and composite source configurations) and laser ablation. The authors look at the relevant parameters for each and evaluate the advantages and disadvantages of each technique. In addition, promising work on in situ oxidation is discussed. Also addressed are efforts to find optimum substrate materials and substrate buffer layers for various applications. The current state of the art for T c , J c and H c2 is presented for the yttrium, bismuth, and thallium compounds

  19. 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.

  20. Magnetization in permalloy thin films

    Indian Academy of Sciences (India)

    Thin films of permalloy (Ni80Fe20) were prepared using an Ar+N2 mixture with magnetron ... alloys of Ni and Fe) take an important place. NiFe alloy with a ... room temperature (∼298 K, without intentional heating) on Si(100) substrates. A base pressure of 1×10−6 mbar was achieved prior to the deposition. Three different ...

  1. Thin-Film Material Science and Processing | Materials Science | NREL

    Science.gov (United States)

    Thin-Film Material Science and Processing Thin-Film Material Science and Processing Photo of a , a prime example of this research is thin-film photovoltaics (PV). Thin films are important because cadmium telluride thin film, showing from top to bottom: glass, transparent conducting oxide (thin layer

  2. Photoconductivity of thin organic films

    International Nuclear Information System (INIS)

    Tkachenko, Nikolai V.; Chukharev, Vladimir; Kaplas, Petra; Tolkki, Antti; Efimov, Alexander; Haring, Kimmo; Viheriaelae, Jukka; Niemi, Tapio; Lemmetyinen, Helge

    2010-01-01

    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 (C 60 ), 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 C 60 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 10 3 Ω m and 3 x 10 4 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 10 8 Ω m in dark to 3.1 x 10 6 Ω m under the light.

  3. Flexible thin film magnetoimpedance sensors

    International Nuclear Information System (INIS)

    Kurlyandskaya, G.V.; Fernández, E.; Svalov, A.; Burgoa Beitia, A.; García-Arribas, A.; Larrañaga, A.

    2016-01-01

    Magnetically soft thin film deposited onto polymer substrates is an attractive option for flexible electronics including magnetoimpedance (MI) applications. MI FeNi/Ti based thin film sensitive elements were designed and prepared using the sputtering technique by deposition onto rigid and flexible substrates at different deposition rates. Their structure, magnetic properties and MI were comparatively analyzed. The main structural features were sufficiently accurately reproduced in the case of deposition onto cyclo olefine polymer substrates compared to glass substrates for the same conditions. Although for the best condition (28 nm/min rate) of the deposition onto polymer a significant reduction of the MI field sensitivity was found satisfactory for sensor applications sensitivity: 45%/Oe was obtained for a frequency of 60 MHz. - Highlights: • [FeNi/Ti] 3 /Cu/[FeNi/Ti] 3 films were prepared by sputtering at different deposition rates. • Polymer substrates insure sufficiently accurate reproducibility of the film structure. • High deposition rate of 28 nm/min insures the highest values of the magnetoimpedance sensitivity. • Deposition onto polymer results in the satisfactory magnetoimpedance sensitivity of 45%/Oe.

  4. Flexible thin film magnetoimpedance sensors

    Energy Technology Data Exchange (ETDEWEB)

    Kurlyandskaya, G.V., E-mail: galina@we.lc.ehu.es [Universidad del País Vasco, UPV/EHU, Departamento de Electricidad y Electrónica, P.O. Box 644, Bilbao 48080 (Spain); Ural Federal University, Laboratory of Magnetic sensoric, Lenin Ave. 51, 620083 Ekaterinburg (Russian Federation); Fernández, E. [BCMaterials UPV-EHU, Vizcaya Science and Technology Park, 48160 Derio (Spain); Svalov, A. [Universidad del País Vasco, UPV/EHU, Departamento de Electricidad y Electrónica, P.O. Box 644, Bilbao 48080 (Spain); Ural Federal University, Laboratory of Magnetic sensoric, Lenin Ave. 51, 620083 Ekaterinburg (Russian Federation); Burgoa Beitia, A. [Universidad del País Vasco, UPV/EHU, Departamento de Electricidad y Electrónica, P.O. Box 644, Bilbao 48080 (Spain); García-Arribas, A. [Universidad del País Vasco, UPV/EHU, Departamento de Electricidad y Electrónica, P.O. Box 644, Bilbao 48080 (Spain); BCMaterials UPV-EHU, Vizcaya Science and Technology Park, 48160 Derio (Spain); Larrañaga, A. [SGIker, Servicios Generales de Investigación, Universidad del País Vasco (UPV/EHU), 48080 Bilbao (Spain)

    2016-10-01

    Magnetically soft thin film deposited onto polymer substrates is an attractive option for flexible electronics including magnetoimpedance (MI) applications. MI FeNi/Ti based thin film sensitive elements were designed and prepared using the sputtering technique by deposition onto rigid and flexible substrates at different deposition rates. Their structure, magnetic properties and MI were comparatively analyzed. The main structural features were sufficiently accurately reproduced in the case of deposition onto cyclo olefine polymer substrates compared to glass substrates for the same conditions. Although for the best condition (28 nm/min rate) of the deposition onto polymer a significant reduction of the MI field sensitivity was found satisfactory for sensor applications sensitivity: 45%/Oe was obtained for a frequency of 60 MHz. - Highlights: • [FeNi/Ti]{sub 3}/Cu/[FeNi/Ti]{sub 3} films were prepared by sputtering at different deposition rates. • Polymer substrates insure sufficiently accurate reproducibility of the film structure. • High deposition rate of 28 nm/min insures the highest values of the magnetoimpedance sensitivity. • Deposition onto polymer results in the satisfactory magnetoimpedance sensitivity of 45%/Oe.

  5. Characterization of nanocrystalline cadmium telluride thin films ...

    Indian Academy of Sciences (India)

    Unknown

    tion method, successive ionic layer adsorption and reaction (SILAR), are described. For deposition of CdTe thin films ... By conducting several trials optimization of the adsorption, reaction and rinsing time duration for CdTe thin film .... The electrical resistivity of CdTe films was studied in air. Figure 3 shows the variation of log ...

  6. Pressure-induced phase transitions of multiferroic BiFeO3

    OpenAIRE

    XiaoLi, Zhang; Ye, Wu; Qian, Zhang; JunCai, Dong; Xiang, Wu; Jing, Liu; ZiYu, Wu; DongLiang, Chen

    2013-01-01

    Pressure-induced phase transitions of multiferroic BiFeO3 have been investigated using synchrotron radiation X-ray diffraction with diamond anvil cell technique at room temperature. Present experimental data clearly show that rhombohedral (R3c) phase of BiFeO3 first transforms to monoclinic (C2/m) phase at 7 GPa, then to orthorhombic (Pnma) phase at 11 GPa, which is consistent with recent theoretical ab initio calculation. However, we observe another peak at 2{\\theta}=7{\\deg} in the pressure ...

  7. Energy landscape scheme for an intuitive understanding of complex domain dynamics in ferroelectric thin films.

    Science.gov (United States)

    Kim, Tae Heon; Yoon, Jong-Gul; Baek, Seung Hyub; Park, Woong-kyu; Yang, Sang Mo; Yup Jang, Seung; Min, Taeyuun; Chung, Jin-Seok; Eom, Chang-Beom; Noh, Tae Won

    2015-07-01

    Fundamental understanding of domain dynamics in ferroic materials has been a longstanding issue because of its relevance to many systems and to the design of nanoscale domain-wall devices. Despite many theoretical and experimental studies, a full understanding of domain dynamics still remains incomplete, partly due to complex interactions between domain-walls and disorder. We report domain-shape-preserving deterministic domain-wall motion, which directly confirms microscopic return point memory, by observing domain-wall breathing motion in ferroelectric BiFeO3 thin film using stroboscopic piezoresponse force microscopy. Spatial energy landscape that provides new insights into domain dynamics is also mapped based on the breathing motion of domain walls. The evolution of complex domain structure can be understood by the process of occupying the lowest available energy states of polarization in the energy landscape which is determined by defect-induced internal fields. Our result highlights a pathway for the novel design of ferroelectric domain-wall devices through the engineering of energy landscape using defect-induced internal fields such as flexoelectric fields.

  8. Energy landscape scheme for an intuitive understanding of complex domain dynamics in ferroelectric thin films

    Science.gov (United States)

    Heon Kim, Tae; Yoon, Jong-Gul; Hyub Baek, Seung; Park, Woong-Kyu; Mo Yang, Sang; Yup Jang, Seung; Min, Taeyuun; Chung, Jin-Seok; Eom, Chang-Beom; Won Noh, Tae

    2015-07-01

    Fundamental understanding of domain dynamics in ferroic materials has been a longstanding issue because of its relevance to many systems and to the design of nanoscale domain-wall devices. Despite many theoretical and experimental studies, a full understanding of domain dynamics still remains incomplete, partly due to complex interactions between domain-walls and disorder. We report domain-shape-preserving deterministic domain-wall motion, which directly confirms microscopic return point memory, by observing domain-wall breathing motion in ferroelectric BiFeO3 thin film using stroboscopic piezoresponse force microscopy. Spatial energy landscape that provides new insights into domain dynamics is also mapped based on the breathing motion of domain walls. The evolution of complex domain structure can be understood by the process of occupying the lowest available energy states of polarization in the energy landscape which is determined by defect-induced internal fields. Our result highlights a pathway for the novel design of ferroelectric domain-wall devices through the engineering of energy landscape using defect-induced internal fields such as flexoelectric fields.

  9. 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.

  10. Analysis of Hard Thin Film Coating

    Science.gov (United States)

    Shen, Dashen

    1998-01-01

    MSFC is interested in developing hard thin film coating for bearings. The wearing of the bearing is an important problem for space flight engine. Hard thin film coating can drastically improve the surface of the bearing and improve the wear-endurance of the bearing. However, many fundamental problems in surface physics, plasma deposition, etc, need further research. The approach is using electron cyclotron resonance chemical vapor deposition (ECRCVD) to deposit hard thin film an stainless steel bearing. The thin films in consideration include SiC, SiN and other materials. An ECRCVD deposition system is being assembled at MSFC.

  11. On the room temperature multiferroic BiFeO3: magnetic, dielectric and thermal properties

    Science.gov (United States)

    Lu, J.; Günther, A.; Schrettle, F.; Mayr, F.; Krohns, S.; Lunkenheimer, P.; Pimenov, A.; Travkin, V. D.; Mukhin, A. A.; Loidl, A.

    2010-06-01

    Magnetic dc susceptibility between 1.5 and 800 K, ac susceptibility and magnetization, thermodynamic properties, temperature dependence of radio and audio-wave dielectric constants and conductivity, contact-free dielectric constants at mm-wavelengths, as well as ferroelectric polarization are reported for single crystalline BiFeO3. A well developed anomaly in the magnetic susceptibility signals the onset of antiferromagnetic order close to 635 K. Beside this anomaly no further indications of phase or glass transitions are indicated in the magnetic dc and ac susceptibilities down to the lowest temperatures. The heat capacity has been measured from 2 K up to room temperature and significant contributions from magnon excitations have been detected. From the low-temperature heat capacity an anisotropy gap of the magnon modes of the order of 6 meV has been determined. The dielectric constants measured in standard two-point configuration are dominated by Maxwell-Wagner like effects for temperatures T > 300 K and frequencies below 1 MHz. At lower temperatures the temperature dependence of the dielectric constant and loss reveals no anomalies outside the experimental errors, indicating neither phase transitions nor strong spin phonon coupling. The temperature dependence of the dielectric constant was measured contact free at microwave frequencies. At room temperature the dielectric constant has an intrinsic value of 53. The loss is substantial and strongly frequency dependent indicating the predominance of hopping conductivity. Finally, in small thin samples we were able to measure the ferroelectric polarization between 10 and 200 K. The saturation polarization is of the order of 40 μC/cm2, comparable to reports in literature.

  12. Progress in thin film techniques

    International Nuclear Information System (INIS)

    Weingarten, W.

    1996-01-01

    Progress since the last Workshop is reported on superconducting accelerating RF cavities coated with thin films. The materials investigated are Nb, Nb 3 Sn, NbN and NbTiN, the techniques applied are diffusion from the vapour phase (Nb 3 Sn, NbN), the bronze process (Nb 3 Sn), and sputter deposition on a copper substrate (Nb, NbTiN). Specially designed cavities for sample evaluation by RF methods have been developed (triaxial cavity). New experimental techniques to assess the RF amplitude dependence of the surface resistance are presented (with emphasis on niobium films sputter deposited on copper). Evidence is increasing that they are caused by magnetic flux penetration into the surface layer. (R.P.)

  13. High temperature superconductor thin films

    International Nuclear Information System (INIS)

    Correra, L.

    1992-01-01

    Interdisciplinary research on superconducting oxides is the main focus of the contributors in this volume. Several aspects of the thin film field from fundamental properties to applications are examined. Interesting results for the Bi system are also reviewed. The 132 papers, including 8 invited, report mainly on the 1-2-3 system, indicating that the Y-Ba-Cu-O and related compounds are still the most intensively studied materials in this field. The volume attests to the significant progress that has been made in this field, as well as reporting on the challenging problems that still remain to be solved. The papers are presented in five chapters, subsequently on properties, film growth and processing, substrates and multilayers, structural characterization, and applications

  14. Minerals deposited as thin films

    International Nuclear Information System (INIS)

    Vazquez, Cristina; Leyt, D.V. de; Custo, Graciela

    1987-01-01

    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) [es

  15. Thin Film Photovoltaic Partnership Project | Photovoltaic Research | NREL

    Science.gov (United States)

    Thin Film Photovoltaic Partnership Project Thin Film Photovoltaic Partnership Project NREL's Thin Film Photovoltaic (PV) Partnership Project led R&D on emerging thin-film solar technologies in the United States from 1994 to 2009. The project made many advances in thin-film PV technologies that allowed

  16. 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...

  17. Local Weak Ferromagnetism in Single-Crystalline Ferroelectric BiFeO3

    DEFF Research Database (Denmark)

    Ramazanoglu, M.; Laver, Mark; Ratcliff, W.

    2011-01-01

    Polarized small-angle neutron scattering studies of single-crystalline multiferroic BiFeO3 reveal a long-wavelength spin density wave generated by ∼1° spin canting of the spins out of the rotation plane of the antiferromagnetic cycloidal order. This signifies weak ferromagnetism within mesoscopic...

  18. 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...

  19. Excimer Laser Deposition of PLZT Thin Films

    National Research Council Canada - National Science Library

    Petersen, GAry

    1991-01-01

    .... In order to integrate these devices into optical systems, the production of high quality thin films with high transparency and perovskite crystal structure is desired. This requires development of deposition technologies to overcome the challenges of depositing and processing PLZT thin films.

  20. Thin films of mixed metal compounds

    Science.gov (United States)

    Mickelsen, Reid A.; Chen, Wen S.

    1985-01-01

    A compositionally uniform thin film of a mixed metal compound is formed by simultaneously evaporating a first metal compound and a second metal compound from independent sources. The mean free path between the vapor particles is reduced by a gas and the mixed vapors are deposited uniformly. The invention finds particular utility in forming thin film heterojunction solar cells.

  1. Field ion microscope studies on thin films

    International Nuclear Information System (INIS)

    Cavaleru, A.; Scortaru, A.

    1976-01-01

    A review of the progress made in the last years in FIM application to thin film structure studies and adatom properties important in the nucleation stage of thin film growth: substrate binding and mobility of individual adatoms, behaviour of adatoms clusters is presented. (author)

  2. Cellulose triacetate, thin film dielectric capacitor

    Science.gov (United States)

    Yen, Shiao-Ping S. (Inventor); Jow, T. Richard (Inventor)

    1995-01-01

    Very thin films of cellulose triacetate are cast from a solution containing a small amount of high boiling temperature, non-solvent which evaporates last and lifts the film from the casting surface. Stretched, oriented, crystallized films have high electrical breakdown properties. Metallized films less than about 2 microns in thickness form self-healing electrodes for high energy density, pulsed power capacitors. Thicker films can be utilized as a dielectric for a capacitor.

  3. 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

  4. BDS thin film damage competition

    Science.gov (United States)

    Stolz, Christopher J.; Thomas, Michael D.; Griffin, Andrew J.

    2008-10-01

    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. Method of producing thin cellulose nitrate film

    International Nuclear Information System (INIS)

    Lupica, S.B.

    1975-01-01

    An improved method for forming a thin nitrocellulose film of reproducible thickness is described. The film is a cellulose nitrate film, 10 to 20 microns in thickness, cast from a solution of cellulose nitrate in tetrahydrofuran, said solution containing from 7 to 15 percent, by weight, of dioctyl phthalate, said cellulose nitrate having a nitrogen content of from 10 to 13 percent

  6. Macro stress mapping on thin film buckling

    Energy Technology Data Exchange (ETDEWEB)

    Goudeau, P.; Villain, P.; Renault, P.-O.; Tamura, N.; Celestre, R.S.; Padmore, H.A.

    2002-11-06

    Thin films deposited by Physical Vapour Deposition techniques on substrates generally exhibit large residual stresses which may be responsible of thin film buckling in the case of compressive stresses. Since the 80's, a lot of theoretical work has been done to develop mechanical models but only a few experimental work has been done on this subject to support these theoretical approaches and nothing concerning local stress measurement mainly because of the small dimension of the buckling (few 10th mm). This paper deals with the application of micro beam X-ray diffraction available on synchrotron radiation sources for stress mapping analysis of gold thin film buckling.

  7. Ferroelectric BiFeO3as an Oxide Dye in Highly Tunable Mesoporous All-Oxide Photovoltaic Heterojunctions

    KAUST Repository

    Wang, Lingfei; Ma, He; Chang, Lei; Ma, Chun; Yuan, Guoliang; Wang, Junling; Wu, Tao

    2016-01-01

    As potential photovoltaic materials, transition-metal oxides such as BiFeO3 (BFO) are capable of absorbing a substantial portion of solar light and incorporating ferroic orders into solar cells with enhanced performance. But the photovoltaic

  8. Pressure-induced phase transitions of multiferroic BiFeO3

    International Nuclear Information System (INIS)

    Zhang Xiaoli; Dong Juncai; Liu Jing; Chen Dongliang; Wu Ye; Zhang Qian; Wu Xiang; Wu Ziyu

    2013-01-01

    Pressure-induced phase transitions of multiferroic BiFeO 3 have been investigated using synchrotron radiation X-ray diffraction with diamond anvil cell technique at room temperature. Present experimental data clearly show that rhombohedral (R3c) phase of BiFeO 3 first transforms to monoclinic (C2/m) phase at 7 GPa, then to orthorhombic (Pnma) phase at 11 GPa, which is consistent with recent theoretical ab initio calculation. However, we observe another peak at 2θ=7° in the pressure range of 5-7 GPa that has not been reported previously. Further analysis reveals that this reflection peak is attributed to the orthorhombic (Pbam) phase, indicating the coexistence of monoclinic phase with orthorhombic phase in low pressure range. (authors)

  9. Giant electroresistance of super-tetragonal BiFeO3-based ferroelectric tunnel junctions.

    Science.gov (United States)

    Yamada, Hiroyuki; Garcia, Vincent; Fusil, Stéphane; Boyn, Sören; Marinova, Maya; Gloter, Alexandre; Xavier, Stéphane; Grollier, Julie; Jacquet, Eric; Carrétéro, Cécile; Deranlot, Cyrile; Bibes, Manuel; Barthélémy, Agnès

    2013-06-25

    Ferroelectric tunnel junctions enable a nondestructive readout of the ferroelectric state via a change of resistance induced by switching the ferroelectric polarization. We fabricated submicrometer solid-state ferroelectric tunnel junctions based on a recently discovered polymorph of BiFeO3 with giant axial ratio ("T-phase"). Applying voltage pulses to the junctions leads to the highest resistance changes (OFF/ON ratio >10,000) ever reported with ferroelectric tunnel junctions. Along with the good retention properties, this giant effect reinforces the interest in nonvolatile memories based on ferroelectric tunnel junctions. We also show that the changes in resistance scale with the nucleation and growth of ferroelectric domains in the ultrathin BiFeO3 (imaged by piezoresponse force microscopy), thereby suggesting potential as multilevel memory cells and memristors.

  10. Solid thin film materials for use in thin film charge-coupled devices

    International Nuclear Information System (INIS)

    Lynch, S.J.

    1983-01-01

    Solid thin films deposited by vacuum deposition were evaluated to ascertain their effectiveness for use in the manufacturing of charge-coupled devices (CCDs). Optical and electrical characteristics of tellurium and Bi 2 Te 3 solid thin films were obtained in order to design and to simulate successfully the operation of thin film (TF) CCDs. In this article some of the material differences between single-crystal material and the island-structured thin film used in TFCCDs are discussed. The electrical parameters were obtained and tabulated, e.g. the mobility, conductivity, dielectric constants, permittivity, lifetime of holes and electrons in the thin films and drift diffusion constants. The optical parameters were also measured and analyzed. After the design was complete, experimental TFCCDs were manufactured and were successfully operated utilizing the aforementioned solid thin films. (Auth.)

  11. Passivation Effects in Copper Thin Films

    International Nuclear Information System (INIS)

    Wiederhirn, G.; Nucci, J.; Richter, G.; Arzt, E.; Balk, T. J.; Dehm, G.

    2006-01-01

    We studied the influence of a 10 nm AlxOy passivation on the stress-temperature behavior of 100 nm and 1 μm thick Cu films. At low temperatures, the passivation induces a large tensile stress increase in the 100 nm film; however, its effect on the 1 μm film is negligible. At high temperatures, the opposite behavior is observed; while the passivation does not change the 100 nm film behavior, it strengthens the 1 μm film by driving it deeper into compression. These observations are explained in light of a combination of constrained diffusional creep and dislocation dynamics unique to ultra-thin films

  12. Ferroelectric control of magnetization in BiFeO3/CoFe heterostructures.

    Science.gov (United States)

    Gajek, Martin; Martin, Lane; Heron, John; Seidel, Jan; Ramesh, Ramamoorthy

    2009-03-01

    The cross coupling between ferroic order parameters in multiferroics opens an alternative for the control of magnetism in magnetoelectric devices by purely electrical means. We first report on the exchange coupling between BiFeO3, an antiferromagnetic ferroelectric , and CoFe. We then show that the domain structure of the ferromagnet can be changed by poling the ferroelectric layer. Finally, we will discuss the implementation of our findings into possible device schemes.

  13. Thermal conductivity model for nanoporous thin films

    Science.gov (United States)

    Huang, Congliang; Zhao, Xinpeng; Regner, Keith; Yang, Ronggui

    2018-03-01

    Nanoporous thin films have attracted great interest because of their extremely low thermal conductivity and potential applications in thin thermal insulators and thermoelectrics. Although there are some numerical and experimental studies about the thermal conductivity of nanoporous thin films, a simplified model is still needed to provide a straightforward prediction. In this paper, by including the phonon scattering lifetimes due to film thickness boundary scattering, nanopore scattering and the frequency-dependent intrinsic phonon-phonon scattering, a fitting-parameter-free model based on the kinetic theory of phonon transport is developed to predict both the in-plane and the cross-plane thermal conductivities of nanoporous thin films. With input parameters such as the lattice constants, thermal conductivity, and the group velocity of acoustic phonons of bulk silicon, our model shows a good agreement with available experimental and numerical results of nanoporous silicon thin films. It illustrates that the size effect of film thickness boundary scattering not only depends on the film thickness but also on the size of nanopores, and a larger nanopore leads to a stronger size effect of the film thickness. Our model also reveals that there are different optimal structures for getting the lowest in-plane and cross-plane thermal conductivities.

  14. Ferroelectric and magnetic properties in high-pressure synthesized BiFeO3 compound

    International Nuclear Information System (INIS)

    Zhai, L.; Shi, Y.G.; Gao, J.L.; Tang, S.L.; Du, Y.W.

    2011-01-01

    Highlights: → A high-density polycrystalline BiFeO 3 compound was synthesized by high-pressure annealing method. → The sample showed weak ferromagnetic at room temperature, which could be attributed to the lattice distortion induced by the high-pressure annealing. → Irregular domains were observed on the surface of the sample by piezoresponse force microscopy, and a typical hysteresis loop was obtained. - Abstract: High-density polycrystalline BiFeO 3 compound was synthesized by high-pressure annealing. Measurements of crystal structure, magnetic, and ferroelectric properties were made on the sample. It was found that the sample was almost single phase with a distorted R3c structure. The results of the X-ray photoelectron spectra demonstrate that the oxidation state of Fe in the sample is Fe 3+ . The room-temperature field dependence of magnetization for BiFeO 3 exhibits a hysteretic behavior. The observed weak ferromagnetism could be ascribed to the lattice distortion induced by the high-pressure annealing. In addition, the local ferroelectric performance of the sample was studied by piezoresponse force microscopy.

  15. Photocatalytic performances of BiFeO3 particles with the average size in nanometer, submicrometer, and micrometer

    International Nuclear Information System (INIS)

    Hao, Chunxue; FushengWen,; Xiang, Jianyong; Hou, Hang; Lv, Weiming; Lv, Yifei; Hu, Wentao; Liu, Zhongyuan

    2014-01-01

    Highlights: • Three different synthesis routes have been taken to successfully prepare the BiFeO 3 particles with the different morphologies and average size in 50, 500 nm, and 15 μm. • For photodegradation of dyes under visible irradiation in the presence of BiFeO 3 , the photocatalytic efficiency increases quickly with the decrease in size. • The enhanced photocatalytic efficiency of BiFeO 3 nanoparticles may attribute to more surface active catalytic-sites and shorter distances carriers have to migrate to the surface reaction sites. - Abstract: Three different synthesis routes were taken to successfully prepare the BiFeO 3 particles with the different morphologies and average size in 50, 500 nm, and 15 μm, respectively. The crystal structure was recognized to be a distorted rhombohedral one with the space group R3c. With the decrease in particle size, obvious decrease in peak intensity and redshift in peak position were observed for the Raman active bands. The narrow band gap was determined from the UV–vis absorption spectra, indicating the semiconducting nature of the BiFeO 3 . For photodegradation of dyes under visible irradiation in the presence of BiFeO 3 , the photocatalytic efficiency increased quickly with the decrease in size which may attribute to more surface active catalytic-sites and shorter distances carriers had to migrate to the surface reaction sites

  16. Structural, magnetic, and electrical properties of Gd-doped BiFeO3 nanoparticles with reduced particle size

    International Nuclear Information System (INIS)

    Lotey, Gurmeet Singh; Verma, N. K.

    2012-01-01

    Pure and Gd-doped BiFeO 3 nanoparticles have been synthesized by sol–gel method. The significant effects of size and Gd-doping on structural, electrical, and magnetic properties have been investigated. X-ray diffraction study reveals that the pure BiFeO 3 nanoparticles possess rhombohedral structure, but with 10% Gd-doping complete structural transformation from rhombohedral to orthorhombic has been observed. The particle size of pure and Gd-doped BiFeO 3 nanoparticles, calculated using Transmission electron microscopy, has been found to be in the range 25–15 nm. Pure and Gd-doped BiFeO 3 nanoparticles show ferromagnetic character, and the magnetization increases with decrease in particle size and increase in doping concentration. Scanning electron microscopy study reveals that grain size decreases with increase in Gd concentration. Well-saturated polarization versus electric field loop is observed for the doped samples. Leakage current density decreases by four orders by doping Gd in BiFeO 3 . The incorporation of Gd in BiFeO 3 enhances spin as well as electric polarization at room temperature. The possible origin of enhancement in these properties has been explained on the basis of dopant and its concentration, phase purity, small particle, and grain size.

  17. Epitaxy, thin films and superlattices

    International Nuclear Information System (INIS)

    Jagd Christensen, Morten

    1997-05-01

    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)

  18. Epitaxy, thin films and superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Jagd Christensen, Morten

    1997-05-01

    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) 14 tabs.; 58 ills., 96 refs.

  19. Flush Mounting Of Thin-Film Sensors

    Science.gov (United States)

    Moore, Thomas C., Sr.

    1992-01-01

    Technique developed for mounting thin-film sensors flush with surfaces like aerodynamic surfaces of aircraft, which often have compound curvatures. Sensor mounted in recess by use of vacuum pad and materials selected for specific application. Technique involves use of materials tailored to thermal properties of substrate in which sensor mounted. Together with customized materials, enables flush mounting of thin-film sensors in most situations in which recesses for sensors provided. Useful in both aircraft and automotive industries.

  20. Thin film description by wavelet coefficients statistics

    Czech Academy of Sciences Publication Activity Database

    Boldyš, Jiří; Hrach, R.

    2005-01-01

    Roč. 55, č. 1 (2005), s. 55-64 ISSN 0011-4626 Grant - others:GA UK(CZ) 173/2003 Institutional research plan: CEZ:AV0Z10750506 Keywords : thin films * wavelet transform * descriptors * histogram model Subject RIV: BD - Theory of Information Impact factor: 0.360, year: 2005 http://library.utia.cas.cz/separaty/2009/ZOI/boldys-thin film description by wavelet coefficients statistics .pdf

  1. Photoluminescence properties of perovskite multilayer thin films

    Energy Technology Data Exchange (ETDEWEB)

    Macario, Leilane Roberta; Longo, Elson, E-mail: leilanemacario@gmail.com [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil); Mazzo, Tatiana Martelli [Universidade Federal de Sao Paulo (UNIFESP), SP (Brazil); Bouquet, Valerie; Deputier, Stephanie; Ollivier, Sophie; Guilloux-Viry, Maryline [Universite de Rennes (France)

    2016-07-01

    Full text: The knowledge of the optical properties of thin films is important in many scientific, technological and industrial applications of thin films such as photoconductivity, solar energy, photography, and numerous other applications [1]. In this study, perovskite type oxides were grown by pulsed laser deposition [2] in order to obtain thin films with applicable optical properties. The LaNiO{sub 3} (LN), BaTiO{sub 3} (BT) and KNbO{sub 3} (KNb) targets were prepared by solid-state reaction. The X-ray Diffraction revealed the presence of the desired phases, containing the elements of interest in the targets and in the thin films that were produced. The LN, BT and KNb thin films were polycrystalline and the corresponding diffraction peaks were indexed in the with JCPDS cards n. 00-033-0711, n. 00-005-0626, and n. 00-009-0156, respectively. The multilayers films were polycrystalline. The majority of the micrographs obtained by scanning electron microscopy presented films with a thickness from 100 to 400 nm. The photoluminescent (PL) emission spectra of thin films show different broad bands that occupies large region of the visible spectrum, ranging from about 300-350 to 600-650 nm of the electromagnetic spectrum. The PL emission is associated with the order-disorder structural, even small structural changes can modify the interactions between electronic states. The structural disorder results in formation of new energy levels in the forbidden region. The proximity or distance of these new energy levels formed in relation to valence band and to the conduction band results in PL spectra located at higher or lower energies. These interactions change the electronic states which can be influenced by defects, particularly the interface defects between the layers of the thin films. The presence of defects results in changes in the broad band matrix intensity and in displacement of the PL emission maximum. (author)

  2. Nanosphere lithography applied to magnetic thin films

    Science.gov (United States)

    Gleason, Russell

    Magnetic nanostructures have widespread applications in many areas of physics and engineering, and nanosphere lithography has recently emerged as promising tool for the fabrication of such nanostructures. The goal of this research is to explore the magnetic properties of a thin film of ferromagnetic material deposited onto a hexagonally close-packed monolayer array of polystyrene nanospheres, and how they differ from the magnetic properties of a typical flat thin film. The first portion of this research focuses on determining the optimum conditions for depositing a monolayer of nanospheres onto chemically pretreated silicon substrates (via drop-coating) and the subsequent characterization of the deposited nanosphere layer with scanning electron microscopy. Single layers of permalloy (Ni80Fe20) are then deposited on top of the nanosphere array via DC magnetron sputtering, resulting in a thin film array of magnetic nanocaps. The coercivities of the thin films are measured using a home-built magneto-optical Kerr effect (MOKE) system in longitudinal arrangement. MOKE measurements show that for a single layer of permalloy (Py), the coercivity of a thin film deposited onto an array of nanospheres increases compared to that of a flat thin film. In addition, the coercivity increases as the nanosphere size decreases for the same deposited layer. It is postulated that magnetic exchange decoupling between neighboring nanocaps suppresses the propagation of magnetic domain walls, and this pinning of the domain walls is thought to be the primary source of the increase in coercivity.

  3. Tailoring electronic structure of polyazomethines thin films

    OpenAIRE

    J. Weszka; B. Hajduk; M. Domański; M. Chwastek; J. Jurusik; B. Jarząbek; H. Bednarski; P. Jarka

    2010-01-01

    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 ...

  4. Electrochemical fabrication of nanoporous polypyrrole thin films

    International Nuclear Information System (INIS)

    Li Mei; Yuan Jinying; Shi Gaoquan

    2008-01-01

    Polypyrrole thin films with pores in nanometer scale were synthesized by direct electrochemical oxidation of pyrrole in a mixed electrolyte of isopropyl alcohol, boron trifluoride diethyl etherate, sodium dodecylsulfonate and poly(ethylene glycol) using well-aligned ZnO nanowires arrays as templates. The thin films exhibit high conductivity of ca. σ rt ∼ 20.5 s/cm and can be driven to bend during redox processes in 1.0 M lithium perchlorate aqueous solution. The movement rate of an actuator based on this nanoporous film was measured to be over 90 o /s at a driving potential of 0.8 V (vs. Ag/AgCl)

  5. Polymer surfaces, interfaces and thin films

    Energy Technology Data Exchange (ETDEWEB)

    Stamm, M [Max-Planck-Institut fuer Polymerforschung, Mainz (Germany)

    1996-11-01

    Neutron reflectometry can be used in various ways to investigate surfaces, interfaces and thin films of polymers. Its potential comes mostly from the possibilities offered by selective deuteration, where a particular component can be made visible with respect to its activity at the interface. In addition the depth resolution is much better than with most other direct techniques, and details of the profiles may be resolved. Several examples will be discussed including the segment diffusion at the interface between two polymer films, the determination of the narrow interfaces between incompatible polymer blends and the development of order in thin diblock copolymer films. (author) 10 figs., 2 tabs., 38 refs.

  6. Polymer surfaces, interfaces and thin films

    International Nuclear Information System (INIS)

    Stamm, M.

    1996-01-01

    Neutron reflectometry can be used in various ways to investigate surfaces, interfaces and thin films of polymers. Its potential comes mostly from the possibilities offered by selective deuteration, where a particular component can be made visible with respect to its activity at the interface. In addition the depth resolution is much better than with most other direct techniques, and details of the profiles may be resolved. Several examples will be discussed including the segment diffusion at the interface between two polymer films, the determination of the narrow interfaces between incompatible polymer blends and the development of order in thin diblock copolymer films. (author) 10 figs., 2 tabs., 38 refs

  7. Simulated Thin-Film Growth and Imaging

    Science.gov (United States)

    Schillaci, Michael

    2001-06-01

    Thin-films have become the cornerstone of the electronics, telecommunications, and broadband markets. A list of potential products includes: computer boards and chips, satellites, cell phones, fuel cells, superconductors, flat panel displays, optical waveguides, building and automotive windows, food and beverage plastic containers, metal foils, pipe plating, vision ware, manufacturing equipment and turbine engines. For all of these reasons a basic understanding of the physical processes involved in both growing and imaging thin-films can provide a wonderful research project for advanced undergraduate and first-year graduate students. After producing rudimentary two- and three-dimensional thin-film models incorporating ballsitic deposition and nearest neighbor Coulomb-type interactions, the QM tunneling equations are used to produce simulated scanning tunneling microscope (SSTM) images of the films. A discussion of computational platforms, languages, and software packages that may be used to accomplish similar results is also given.

  8. Restructuring in block copolymer thin films

    DEFF Research Database (Denmark)

    Posselt, Dorthe; Zhang, Jianqi; Smilgies, Detlef-M.

    2017-01-01

    Block copolymer (BCP) thin films have been proposed for a number of nanotechnology applications, such as nanolithography and as nanotemplates, nanoporous membranes and sensors. Solvent vapor annealing (SVA) has emerged as a powerful technique for manipulating and controlling the structure of BCP...... thin films, e.g., by healing defects, by altering the orientation of the microdomains and by changing the morphology. Due to high time resolution and compatibility with SVA environments, grazing-incidence small-angle X-ray scattering (GISAXS) is an indispensable technique for studying the SVA process......, providing information of the BCP thin film structure both laterally and along the film normal. Especially, state-of-the-art combined GISAXS/SVA setups at synchrotron sources have facilitated in situ and real-time studies of the SVA process with a time resolution of a few seconds, giving important insight...

  9. Nanostructured thin films as functional coatings

    Energy Technology Data Exchange (ETDEWEB)

    Lazar, Manoj A; Tadvani, Jalil K; Tung, Wing Sze; Lopez, Lorena; Daoud, Walid A, E-mail: Walid.Daoud@sci.monash.edu.au [School of Applied Sciences and Engineering, Monash University, Churchill, VIC 3842 (Australia)

    2010-06-15

    Nanostructured thin films is one of the highly exploiting research areas particularly in applications such as photovoltaics, photocatalysis and sensor technologies. Highly tuned thin films, in terms of thickness, crystallinity, porosity and optical properties, can be fabricated on different substrates using the sol-gel method, chemical solution deposition (CSD), electrochemical etching, along with other conventional methods such as chemical vapour deposition (CVD) and physical vapour deposition (PVD). The above mentioned properties of these films are usually characterised using surface analysis techniques such as XRD, SEM, TEM, AFM, ellipsometry, electrochemistry, SAXS, reflectance spectroscopy, STM, XPS, SIMS, ESCA, X-ray topography and DOSY-NMR. This article presents a short review of the preparation and characterisation of thin films of nanocrystalline titanium dioxide and modified silicon as well as their application in solar cells, water treatment, water splitting, self cleaning fabrics, sensors, optoelectronic devices and lab on chip systems.

  10. DC magnetron sputtering prepared Ag-C thin film anode for thin film lithium ion microbatteries

    International Nuclear Information System (INIS)

    Li, Y.; Tu, J.P.; Shi, D.Q.; Huang, X.H.; Wu, H.M.; Yuan, Y.F.; Zhao, X.B.

    2007-01-01

    An Ag-C thin film was prepared by DC magnetron co-sputtering, using pure silver and graphite as the targets. The microstructure and morphology of the deposited thin film were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Electrochemical performances of the Ag-C thin film anode were investigated by means of discharge/charge and cyclic voltammogram (CV) tests in model cells. The electrochemical impedance spectrum (EIS) characteristics and the chemical diffusion coefficient, D Li of the Ag-C thin film electrode at different discharging states were discussed. It was believed that the excellent cycling performance of the Ag-C electrode was ascribed to the good conductivity of silver and the volume stability of the thin film

  11. Microscopic local fatigue in PZT thin films

    International Nuclear Information System (INIS)

    Li, B S; Wu, A; Vilarinho, P M

    2007-01-01

    The reduction in switchable polarization during fatigue largely limits the application of PZT thin films in ferroelectric nonvolatile memories. So, it is very important to understand the fatigue mechanism in PZT films, especially at a nanoscale level. In this paper, nanoscale fatigue properties in PZT thin films have been studied by piezoresponse force microscopy and local piezoloops. It has been found that a piezoloop obtained on a fatigued point exhibits a much more pinched shape and a local imprint phenomenon is observed after severe fatigue. Furthermore, the domain structure evolves from a simple single-peak profile to a complex fluctuant one. However, there is only some shift of the piezoloop when a unipolar field with the same amplitude is applied on the film. The available experimental data show that there exist obvious domain wall pinning and injection of electrons into the film during fatigue. Finally, a schematic illustration is suggested to explain the possible fatigue mechanism

  12. Optical constant of thin gold films

    DEFF Research Database (Denmark)

    Yakubovsky, D. I.; Fedyanin, D. Yu; Arsenin, A. V.

    2017-01-01

    The performance of metal-based devices is limited by ohmic losses in the metal, which are determined by electron scattering. The structural properties of gold thin films also play an important role in the film quality, which may affect its' optical properties and the overall capability...... and spectroscopic ellipsometry, the structural morphology and optical properties of polycrystalline gold thin films (fabricated by e-beam deposition at a low sputtering rate smooth gold) in the thickness range of 20 - 200 nm. By extracting the real and imaginary dielectric function and the Drude parameter...... of the device. At the same time, metal films of different thicknesses are needed for different applications and, since these films are polycrystalline, their internal properties and surface roughness can greatly vary from one thickness to another. In this work, we study, using atomic force microscopy...

  13. Thermal conductivity of nanoscale thin nickel films

    Institute of Scientific and Technical Information of China (English)

    YUAN Shiping; JIANG Peixue

    2005-01-01

    The inhomogeneous non-equilibrium molecular dynamics (NEMD) scheme is applied to model phonon heat conduction in thin nickel films. The electronic contribution to the thermal conductivity of the film is deduced from the electrical conductivity through the use of the Wiedemann-Franz law. At the average temperature of T = 300 K, which is lower than the Debye temperature ()D = 450 K,the results show that in a film thickness range of about 1-11 nm, the calculated cross-plane thermal conductivity decreases almost linearly with the decreasing film thickness, exhibiting a remarkable reduction compared with the bulk value. The electrical and thermal conductivities are anisotropic in thin nickel films for the thickness under about 10 nm. The phonon mean free path is estimated and the size effect on the thermal conductivity is attributed to the reduction of the phonon mean free path according to the kinetic theory.

  14. Magnetostrictive thin films prepared by RF sputtering

    International Nuclear Information System (INIS)

    Carabias, I.; Martinez, A.; Garcia, M.A.; Pina, E.; Gonzalez, J.M.; Hernando, A.; Crespo, P.

    2005-01-01

    Fe 80 B 20 thin films have been prepared by ion beam sputtering magnetron on room temperature. The films were fabricated on different substrates to compare the different magnetic and structural properties. In particular the growth of films on flexible substrates (PDMS, Kapton) has been studied to allow a simple integration of the system in miniaturized magnetostrictive devices. X-ray diffraction patterns indicate that films are mainly amorphous although the presence of some Fe nanoparticles cannot be ruled out. The coercive field of thin films ranges between 15 and 35 Oe, depending on substrate. Magnetostriction measurements indicate the strong dependence of the saturation magnetostriction with the substrate. Samples on flexible substrates exhibit a better performance than samples deposited onto glass substrates

  15. Critical behavior of ferromagnetic Ising thin films

    International Nuclear Information System (INIS)

    Cossio, P.; Mazo-Zuluaga, J.; Restrepo, J.

    2006-01-01

    In the present work, we study the magnetic properties and critical behavior of simple cubic ferromagnetic thin films. We simulate LxLxd films with semifree boundary conditions on the basis of the Monte Carlo method and the Ising model with nearest neighbor interactions. A Metropolis dynamics was implemented to carry out the energy minimization process. For different film thickness, in the nanometer range, we compute the temperature dependence of the magnetization, the magnetic susceptibility and the fourth order Binder's cumulant. Bulk and surface contributions of these quantities are computed in a differentiated fashion. Additionally, according to finite size scaling theory, we estimate the critical exponents for the correlation length, magnetic susceptibility, and magnetization. Results reveal a strong dependence of critical temperature and critical exponents on the film thickness. The obtained critical exponents are finally compared to those reported in literature for thin films

  16. Thin Films in the Photovoltaic Industry

    International Nuclear Information System (INIS)

    Jaeger-Waldau, A.

    2008-03-01

    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.

  17. Lithium ion intercalation into thin film anatase

    International Nuclear Information System (INIS)

    Kundrata, I.; Froehlich, K.; Ballo, P.

    2015-01-01

    The aim of this work is to find the optimal parameters for thin film TiO 2 anatase grown by Atomic layer deposition (ALD) for use as electrode in lithium ion batteries. Two parameters, the optimal film thickness and growth conditions are aimed for. Optimal film thickness for achieving optimum between capacity gained from volume and capacity gained by changing of the intercalation constant and optimal growth conditions for film conformity on structured substrates with high aspect ratio. Here we presents first results from this ongoing research and discuss future outlooks. (authors)

  18. Ion beam-based characterization of multicomponent oxide thin films and thin film layered structures

    International Nuclear Information System (INIS)

    Krauss, A.R.; Rangaswamy, M.; Lin, Yuping; Gruen, D.M.; Schultz, J.A.; Schmidt, H.K.; Chang, R.P.H.

    1992-01-01

    Fabrication of thin film layered structures of multi-component materials such as high temperature superconductors, ferroelectric and electro-optic materials, and alloy semiconductors, and the development of hybrid materials requires understanding of film growth and interface properties. For High Temperature Superconductors, the superconducting coherence length is extremely short (5--15 Angstrom), and fabrication of reliable devices will require control of film properties at extremely sharp interfaces; it will be necessary to verify the integrity of thin layers and layered structure devices over thicknesses comparable to the atomic layer spacing. Analytical techniques which probe the first 1--2 atomic layers are therefore necessary for in-situ characterization of relevant thin film growth processes. However, most surface-analytical techniques are sensitive to a region within 10--40 Angstrom of the surface and are physically incompatible with thin film deposition and are typically restricted to ultra high vacuum conditions. A review of ion beam-based analytical methods for the characterization of thin film and multi-layered thin film structures incorporating layers of multicomponent oxides is presented. Particular attention will be paid to the use of time-of-flight techniques based on the use of 1- 15 key ion beams which show potential for use as nondestructive, real-time, in-situ surface diagnostics for the growth of multicomponent metal and metal oxide thin films

  19. Structure and phase transition of BiFeO3 cubic micro-particles prepared by hydrothermal method

    International Nuclear Information System (INIS)

    Zhou, Jian-Ping; Yang, Ruo-Lin; Xiao, Rui-Juan; Chen, Xiao-Ming; Deng, Chao-Yong

    2012-01-01

    Graphical abstract: Bismuth ferrite (BiFeO 3 ) cubic micro-particles with smooth surfaces were synthesized. BiFeO 3 has a hexagonal perovskite structure with a space group R3c below 370 °C and rhombohedral perovskite structure with a space group R3m below 755 °C, undergoes a phase transition in the temperature range of 755–817 °C to a cubic structure, then decompose to liquid and Fe 2 O 3 above 939 °C. Highlights: ► BiFeO 3 micro-particles with smooth surface were synthesized by hydrothermal method. ► BiFeO 3 enjoys hexagonal structure with well element ratio and chemical valence. ► BiFeO 3 transition from rhombohedral phase to cubic phase lasts 60 °C. -- Abstract: Single-phase bismuth ferrite (BiFeO 3 ) powders were synthesized with a hydrothermal method by controlling the experimental conditions carefully. The powder structure, morphology and composition were characterized by using X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscope, Raman measurement and X-ray photoelectron spectroscopy. The particles change from irregular agglomerations to regular cubes with increasing KOH concentration. The large BiFeO 3 cubic particles enjoy much smooth surfaces with well-matched element ratio (Bi:Fe:O = 1:1:3) and chemical valence (Bi 3+ , Fe 3+ and O 2− ). The high temperature XRD and differential scanning calorimetry show that BiFeO 3 powders have a hexagonal perovskite structure with a space group R3c below 370 °C and a rhombohedral structure with a space group R3m below 755 °C. BiFeO 3 undergoes a phase transition in the temperature range of 755–817 °C from rhombohedral structure to a cubic phase, then decomposes to liquid and Fe 2 O 3 above 939 °C.

  20. Organic thin films and surfaces directions for the nineties

    CERN Document Server

    Ulman, Abraham

    1995-01-01

    Physics of Thin Films has been one of the longest running continuing series in thin film science consisting of 20 volumes since 1963. The series contains some of the highest quality studies of the properties ofvarious thin films materials and systems.In order to be able to reflect the development of todays science and to cover all modern aspects of thin films, the series, beginning with Volume 20, will move beyond the basic physics of thin films. It will address the most important aspects of both inorganic and organic thin films, in both their theoretical as well as technological aspects. Ther

  1. Magnetic characterisation of longitudinal thin film media

    International Nuclear Information System (INIS)

    Dova, P.

    1998-09-01

    Magnetic characterisation techniques, as applied to longitudinal thin film media, have been investigated. These included the study of the differentials of the remanence curves, the delta-M plot and the examination of the critical volumes. Several thin film structures, which are currently used or are being considered for future media applications, have been examined using these techniques. Most of the films were Co-alloys with the exception of a set of Barium ferrite films. Both monolayer and multilayer structures were studied. It was found that the study of activation volumes provides a better insight into the reversal mechanisms of magnetic media, especially in the case of complex structures such as multilayer films and films with bicrystal microstructure. Furthermore, an evaluation study of different methods of determining critical volumes showed that the method using time dependence measurements and the micromagnetic approach is the most appropriate. The magnetic characteristics of the thin film media under investigation were correlated with their microstructure and, where possible, with their noise performance. Magnetic force microscopy was also used for acquiring quasi-domain images in the ac-demagnetised state. It was found that in all Co-alloy films the dominant intergranular coupling is magnetising in nature, the level of which is governed by the Cr content in the magnetic layer. In the case of laminated media it was found that when non-magnetic spacers are used, the nature of the interlayer coupling depends on the spacer thickness. In double layer structures with no spacer, the top layer replicates the crystallographic texture of the bottom layer, and the overall film properties are a combination of the two layers. In bicrystal films the coupling is determined by the Cr segregation in the grain boundaries. Furthermore, the presence of stacking faults in bicrystal films deteriorates their thermal stability, but can be prevented by improving the epitaxial

  2. Vibration welding system with thin film sensor

    Science.gov (United States)

    Cai, Wayne W; Abell, Jeffrey A; Li, Xiaochun; Choi, Hongseok; Zhao, Jingzhou

    2014-03-18

    A vibration welding system includes an anvil, a welding horn, a thin film sensor, and a process controller. The anvil and horn include working surfaces that contact a work piece during the welding process. The sensor measures a control value at the working surface. The measured control value is transmitted to the controller, which controls the system in part using the measured control value. The thin film sensor may include a plurality of thermopiles and thermocouples which collectively measure temperature and heat flux at the working surface. A method includes providing a welder device with a slot adjacent to a working surface of the welder device, inserting the thin film sensor into the slot, and using the sensor to measure a control value at the working surface. A process controller then controls the vibration welding system in part using the measured control value.

  3. Solid surfaces, interfaces and thin films

    CERN Document Server

    Lüth, Hans

    2015-01-01

    This book emphasises both experimental and theoretical aspects of surface, interface and thin-film physics. As in previous editions the preparation of surfaces and thin films, their atomic and morphological structure, their vibronic and electronic properties as well as fundamentals of adsorption are treated. Because of their importance in modern information technology and nanostructure research, particular emphasis is paid to electronic surface and interface states, semiconductor space charge layers and heterostructures. A special chapter of the book is devoted to collective phenomena at interfaces and in thin films such as superconductivity and magnetism. The latter topic includes the meanwhile important issues giant magnetoresistance and spin-transfer torque mechanism, both effects being of high interest in information technology. In this new edition, for the first time, the effect of spin-orbit coupling on surface states is treated. In this context the class of the recently detected topological insulators,...

  4. Thin films for the manipulation of light

    International Nuclear Information System (INIS)

    Piegari, Angela; Sytchkova, Anna

    2015-01-01

    The manipulation of light is typically accomplished by a series of optical surfaces on which the incident beam is reflected, or through which the beam is transmitted. Thin film coatings help to modify the behavior of such surfaces for obtaining the desired result: antireflection coatings to reduce reflection losses, high-reflectance mirrors, filters to divide or combine beams of different wavelengths, and many other types. The amount of light that is transmitted or reflected depends on the optical parameters of the materials and on interference phenomena in thin-film structures. Dedicated software is available to design the proper coating for each requirement. There are several applications of optical thin films, many of them are useful in the everyday life, many others are dedicated to scientific purposes, as will be described in this paper [it

  5. Thin Film Photovoltaic/Thermal Solar Panels

    Institute of Scientific and Technical Information of China (English)

    David JOHNSTON

    2008-01-01

    A solar panel is described.in which thin films of semiconductor are deposited onto a metal substrate.The semiconductor-metal combination forms a thin film photovoltaic cell,and also acts as a reflector,absorber tandem, which acts as a solar selective surface,thus enhancing the solar thermal performance of the collector plate.The use of thin films reduces the distance heat is required to flow from the absorbing surface to the metal plate and heat exchange conduits.Computer modelling demonstrated that,by suitable choice of materials,photovohaic efficiency call be maintained,with thermal performance slishtly reduced,compared to that for thermal-only panels.By grading the absorber layer-to reduce the band gap in the lower region-the thermal performance can be improved,approaching that for a thermal-only solar panel.

  6. 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.

  7. Solid Surfaces, Interfaces and Thin Films

    CERN Document Server

    Lüth, Hans

    2010-01-01

    This book emphasises both experimental and theoretical aspects of surface, interface and thin film physics. As in previous editions the preparation of surfaces and thin films, their atomic and morphological, their vibronic and electronic properties as well as fundamentals of adsorption are treated. Because of their importance in modern information technology and nanostructure physics particular emphasis is paid to electronic surface and interface states, semiconductor space charge layers and heterostructures as well as to superconductor/semiconductor interfaces and magnetic thin films. The latter topic was significantly extended in this new edition by more details about the giant magnetoresistance and a section about the spin-transfer torque mechanism including one new problem as exercise. Two new panels about Kerr-effect and spin-polarized scanning tunnelling microscopy were added, too. Furthermore, the meanwhile important group III-nitride surfaces and high-k oxide/semiconductor interfaces are shortly discu...

  8. Domains in Ferroic Crystals and Thin Films

    CERN Document Server

    Tagantsev, Alexander K; Fousek, Jan

    2010-01-01

    Domains in Ferroic Crystals and Thin Films presents experimental findings and theoretical understanding of ferroic (non-magnetic) domains developed during the past 60 years. It addresses the situation by looking specifically at bulk crystals and thin films, with a particular focus on recently-developed microelectronic applications and methods for observation of domains with techniques such as scanning force microscopy, polarized light microscopy, scanning optical microscopy, electron microscopy, and surface decorating techniques. Domains in Ferroic Crystals and Thin Films covers a large area of material properties and effects connected with static and dynamic properties of domains, which are extremely relevant to materials referred to as ferroics. In most solid state physics books, one large group of ferroics is customarily covered: those in which magnetic properties play a dominant role. Numerous books are specifically devoted to magnetic ferroics and cover a wide spectrum of magnetic domain phenomena. In co...

  9. Thin film oxygen partial pressure sensor

    Science.gov (United States)

    Wortman, J. J.; Harrison, J. W.; Honbarrier, H. L.; Yen, J.

    1972-01-01

    The development is described of a laboratory model oxygen partial pressure sensor using a sputtered zinc oxide thin film. The film is operated at about 400 C through the use of a miniature silicon bar. Because of the unique resistance versus temperature relation of the silicon bar, control of the operational temperature is achieved by controlling the resistance. A circuit for accomplishing this is described. The response of sputtered zinc oxide films of various thicknesses to oxygen, nitrogen, argon, carbon dioxide, and water vapor caused a change in the film resistance. Over a large range, film conductance varied approximately as the square root of the oxygen partial pressure. The presence of water vapor in the gas stream caused a shift in the film conductance at a given oxygen partial pressure. A theoretical model is presented to explain the characteristic features of the zinc oxide response to oxygen.

  10. Magnetite thin films: A simulational approach

    International Nuclear Information System (INIS)

    Mazo-Zuluaga, J.; Restrepo, J.

    2006-01-01

    In the present work the study of the magnetic properties of magnetite thin films is addressed by means of the Monte Carlo method and the Ising model. We simulate LxLxd magnetite thin films (d being the film thickness and L the transversal linear dimension) with periodic boundary conditions along transversal directions and free boundary conditions along d direction. In our model, both the three-dimensional inverse spinel structure and the interactions scheme involving tetrahedral and octahedral sites have been considered in a realistic way. Results reveal a power-law dependence of the critical temperature with the film thickness accordingly by an exponent ν=0.81 and ruled out by finite-size scaling theory. Estimates for the critical exponents of the magnetization and the specific heat are finally presented and discussed

  11. 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.

  12. Novel chemical analysis for thin films

    International Nuclear Information System (INIS)

    Usui, Toshio; Kamei, Masayuki; Aoki, Yuji; Morishita, Tadataka; Tanaka, Shoji

    1991-01-01

    Scanning electron microscopy and total-reflection-angle X-ray spectroscopy (SEM-TRAXS) was applied for fluorescence X-ray analysis of 50A- and 125A-thick Au thin films on Si(100). The intensity of the AuM line (2.15 keV) emitted from the Au thin films varied as a function of the take-off angle (θ t ) with respect to the film surface; the intensity of AuM line from the 125A-thick Au thin film was 1.5 times as large as that of SiK α line (1.74 keV) emitted from the Si substrate when θ t = 0deg-3deg, in the vicinity of a critical angle for total external reflection of the AuM line at Si (0.81deg). In addition, the intensity of the AuM line emitted from the 50A-thick Au thin film was also sufficiently strong for chemical analysis. (author)

  13. Perovskite Thin Films via Atomic Layer Deposition

    KAUST Repository

    Sutherland, Brandon R.; Hoogland, Sjoerd; Adachi, Michael M.; Kanjanaboos, Pongsakorn; Wong, Chris T. O.; McDowell, Jeffrey J.; Xu, Jixian; Voznyy, Oleksandr; Ning, Zhijun; Houtepen, Arjan J.; Sargent, Edward H.

    2014-01-01

    © 2014 Wiley-VCH Verlag GmbH & Co. KGaA. (Graph Presented) A new method to deposit perovskite thin films that benefit from the thickness control and conformality of atomic layer deposition (ALD) is detailed. A seed layer of ALD PbS is place-exchanged with PbI2 and subsequently CH3NH3PbI3 perovskite. These films show promising optical properties, with gain coefficients of 3200 ± 830 cm-1.

  14. Perovskite Thin Films via Atomic Layer Deposition

    KAUST Repository

    Sutherland, Brandon R.

    2014-10-30

    © 2014 Wiley-VCH Verlag GmbH & Co. KGaA. (Graph Presented) A new method to deposit perovskite thin films that benefit from the thickness control and conformality of atomic layer deposition (ALD) is detailed. A seed layer of ALD PbS is place-exchanged with PbI2 and subsequently CH3NH3PbI3 perovskite. These films show promising optical properties, with gain coefficients of 3200 ± 830 cm-1.

  15. Mechanical integrity of thin films

    International Nuclear Information System (INIS)

    Hoffman, R.W.

    1979-01-01

    Mechanical considerations starting with the initial film deposition including questions of adhesion and grading the interface are reviewed. Growth stresses, limiting thickness, stress relief, control aging, and creep are described

  16. Mesoscale simulations of confined Nafion thin films

    Science.gov (United States)

    Vanya, P.; Sharman, J.; Elliott, J. A.

    2017-12-01

    The morphology and transport properties of thin films of the ionomer Nafion, with thicknesses on the order of the bulk cluster size, have been investigated as a model system to explain the anomalous behaviour of catalyst/electrode-polymer interfaces in membrane electrode assemblies. We have employed dissipative particle dynamics (DPD) to investigate the interaction of water and fluorocarbon chains, with carbon and quartz as confining materials, for a wide range of operational water contents and film thicknesses. We found confinement-induced clustering of water perpendicular to the thin film. Hydrophobic carbon forms a water depletion zone near the film interface, whereas hydrophilic quartz results in a zone with excess water. There are, on average, oscillating water-rich and fluorocarbon-rich regions, in agreement with experimental results from neutron reflectometry. Water diffusivity shows increasing directional anisotropy of up to 30% with decreasing film thickness, depending on the hydrophilicity of the confining material. A percolation analysis revealed significant differences in water clustering and connectivity with the confining material. These findings indicate the fundamentally different nature of ionomer thin films, compared to membranes, and suggest explanations for increased ionic resistances observed in the catalyst layer.

  17. Processing of thin SU-8 films

    International Nuclear Information System (INIS)

    Keller, Stephan; Blagoi, Gabriela; Lillemose, Michael; Haefliger, Daniel; Boisen, Anja

    2008-01-01

    This paper summarizes the results of the process optimization for SU-8 films with thicknesses ≤5 µm. The influence of soft-bake conditions, exposure dose and post-exposure-bake parameters on residual film stress, structural stability and lithographic resolution was investigated. Conventionally, the SU-8 is soft-baked after spin coating to remove the solvent. After the exposure, a post-exposure bake at a high temperature T PEB ≥ 90 °C is required to cross-link the resist. However, for thin SU-8 films this often results in cracking or delamination due to residual film stress. The approach of the process optimization is to keep a considerable amount of the solvent in the SU-8 before exposure to facilitate photo-acid diffusion and to increase the mobility of the monomers. The experiments demonstrate that a replacement of the soft-bake by a short solvent evaporation time at ambient temperature allows cross-linking of the thin SU-8 films even at a low T PEB = 50 °C. Fourier-transform infrared spectroscopy is used to confirm the increased cross-linking density. The low thermal stress due to the reduced T PEB and the improved structural stability result in crack-free structures and solve the issue of delamination. The knowledge of the influence of different processing parameters on the responses allows the design of optimized processes for thin SU-8 films depending on the specific application

  18. Thin films prepared from tungstate glass matrix

    Energy Technology Data Exchange (ETDEWEB)

    Montanari, B.; Ribeiro, S.J.L.; Messaddeq, Y. [Departamento de Quimica Geral e Inorganica, Instituto de Quimica, Sao Paulo State University-UNESP, CP 355, CEP 14800-900, Araraquara, SP (Brazil); Li, M.S. [Instituto de Fisica, USP, CP 369, CEP 13560-970, Sao Carlos, SP (Brazil); Poirier, G. [Departamento de Ciencias Exatas, UNIFAL-MG, CEP 37130-000, Alfenas-MG (Brazil)], E-mail: gael@unifal-mg.edu.br

    2008-01-30

    Vitreous samples containing high concentrations of WO{sub 3} (above 40% M) have been used as a target to prepare thin films. Such films were deposited using the electron beam evaporation method onto soda-lime glass substrates. These films were characterized by X-ray diffraction (XRD), perfilometry, X-ray energy dispersion spectroscopy (EDS), M-Lines and UV-vis absorption spectroscopy. In this work, experimental parameters were established to obtain stable thin films showing a chemical composition close to the glass precursor composition and with a high concentration of WO{sub 3}. These amorphous thin films of about 4 {mu}m in thickness exhibit a deep blue coloration but they can be bleached by thermal treatment near the glass transition temperature. Such bleached films show several guided modes in the visible region and have a high refractive index. Controlled crystallization was realized and thus it was possible to obtain WO{sub 3} microcrystals in the amorphous phase.

  19. Atomic Structure Control of Silica Thin Films on Pt(111)

    KAUST Repository

    Crampton, Andrew S; Ridge, Claron J.; Rö tzer, Marian David; Zwaschka, Gregor; Braun, Thomas; D'Elia, Valerio; Basset, Jean-Marie; Schweinberger, Florian Frank; Gü nther, Sebastian; Heiz, Ueli

    2015-01-01

    Metal oxide thin films grown on metal single crystals are commonly used to model heterogeneous catalyst supports. The structure and properties of thin silicon dioxide films grown on metal single crystals have only recently been thoroughly

  20. Optical characterization of niobium pentoxide thin films

    International Nuclear Information System (INIS)

    Pawlicka, A.

    1996-01-01

    Thin films of Nb 2 O 5 were obtained by sol-gel method using ultrasonic irradiation and deposited by dip-coating technique. After calcination at temperatures superior than 500 deg C these films (300 nm thick) were characterized by cyclic voltametry and cronoamperometry. The memory measurements, color efficiency, optical density as a function of wave number and applied potential were effectuated to determine their electrochromic properties. The study of electrochromic properties of these films shows that the insertion process of lithium is reversible and changes their coloration from transparent (T=80%) to dark blue (T=20%). (author)

  1. Electrical resistivity of ferrimagnetic magnetite thin film

    International Nuclear Information System (INIS)

    Varshney, Dinesh; Yogi, A.; Kaurav, N.; Gupta, R.P.; Phase, D.M.

    2006-01-01

    We have grown Fe 3 O 4 (III) epitaxial film on Al 2 O 3 (0001) substrate by pulsed laser deposition, with thickness of 130 nm. X-ray diffraction studies of magnetite show the spinel cubic structure of film with preferential (III) orientation. The electrical resistivity measurement demonstrates that the properties of thin film of magnetite are basically similar to those of bulk magnetite and clearly shows semiconductor-insulator transition at Verwey transition temperature (≅140 K). We have found higher Verwey transition temperature when compared with earlier reports on similar type of system. Possible causes for increase in transition temperature are discussed. (author)

  2. Structural and electrical characterization of BiFeO3-NaTaO3 multiferroic

    International Nuclear Information System (INIS)

    Mohanty, Suchismita; Choudhary, R.N.P.; Parida, B.N.; Padhee, R.

    2014-01-01

    Using a standard high-temperature solid-state reaction technique, polycrystalline samples of (Bi 1-x , Na x ) (Fe 1-x , Ta x ) O 3 (x = 0.0, 0.5) were prepared. The formation of the desired materials was confirmed by X-ray diffraction. The surface texture of the prepared materials recorded by scanning electron microscope exhibits a uniform grain distribution with small voids suggesting the formation of high-density pellet samples. The impedance and dielectric properties of the materials were investigated as a function of temperature and frequency. The relative dielectric constant and loss tangent of BiFeO 3 decrease on addition of NaTaO 3 (x = 0.5). The effect of addition of NaTaO 3 on grain and grain boundary contributions in the resistive and capacitive components of BiFeO 3 was studied using complex impedance spectroscopy. The value of activation energy due to both grain and grain boundary of both the samples is nearly same. The nature of variation of dc conductivity confirms the Arrhenius behavior of the materials. Study of frequency dependence of ac conductivity suggests that the materials obey Jonscher's universal power law and the presence of ionic conductivity. (orig.)

  3. Local and average structure of Mn- and La-substituted BiFeO3

    Science.gov (United States)

    Jiang, Bo; Selbach, Sverre M.

    2017-06-01

    The local and average structure of solid solutions of the multiferroic perovskite BiFeO3 is investigated by synchrotron X-ray diffraction (XRD) and electron density functional theory (DFT) calculations. The average experimental structure is determined by Rietveld refinement and the local structure by total scattering data analyzed in real space with the pair distribution function (PDF) method. With equal concentrations of La on the Bi site or Mn on the Fe site, La causes larger structural distortions than Mn. Structural models based on DFT relaxed geometry give an improved fit to experimental PDFs compared to models constrained by the space group symmetry. Berry phase calculations predict a higher ferroelectric polarization than the experimental literature values, reflecting that structural disorder is not captured in either average structure space group models or DFT calculations with artificial long range order imposed by periodic boundary conditions. Only by including point defects in a supercell, here Bi vacancies, can DFT calculations reproduce the literature results on the structure and ferroelectric polarization of Mn-substituted BiFeO3. The combination of local and average structure sensitive experimental methods with DFT calculations is useful for illuminating the structure-property-composition relationships in complex functional oxides with local structural distortions.

  4. Pinning, rotation, and metastability of BiFeO3 cycloidal domains in a magnetic field

    Science.gov (United States)

    Fishman, Randy S.

    2018-01-01

    Earlier models for the room-temperature multiferroic BiFeO3 implicitly assumed that a very strong anisotropy restricts the domain wave vectors q to the threefold-symmetric axis normal to the static polarization P . However, recent measurements demonstrate that the domain wave vectors q rotate within the hexagonal plane normal to P away from the magnetic field orientation m . We show that the previously neglected threefold anisotropy K3 restricts the wave vectors to lie along the threefold axis in zero field. Taking m to lie along a threefold axis, the domain with q parallel to m remains metastable below Bc 1≈7 T. Due to the pinning of domains by nonmagnetic impurities, the wave vectors of the other two domains start to rotate away from m above 5.6 T, when the component of the torque τ =M ×B along P exceeds a threshold value τpin. Since τ =0 when m ⊥q , the wave vectors of those domains never become completely perpendicular to the magnetic field. Our results explain recent measurements of the critical field as a function of field orientation, small-angle neutron scattering measurements of the wave vectors, as well as spectroscopic measurements with m along a threefold axis. The model developed in this paper also explains how the three multiferroic domains of BiFeO3 for a fixed P can be manipulated by a magnetic field.

  5. Surface Plasmon Waves on Thin Metal Films.

    Science.gov (United States)

    Craig, Alan Ellsworth

    Surface-plasmon polaritons propagating on thin metal films bounded by dielectrics of nearly equal refractive indexes comprise two bound modes. Calculations indicate that, while the modes are degenerate on thick films, both the real and the imaginary components of the propagation constants for the modes split into two branches on successively thinner films. Considering these non-degenerate modes, the mode exhibiting a symmetric (antisymmetric) transverse profile of the longitudinally polarized electric field component, has propagation constant components both of which increase (decrease) with decreasing film thickness. Theoretical propagation constant eigenvalue (PCE) curves have been plotted which delineate this dependence of both propagation constant components on film thickness. By means of a retroreflecting, hemispherical glass coupler in an attenuated total reflection (ATR) configuration, light of wavelength 632.8 nm coupled to the modes of thin silver films deposited on polished glass substrates. Lorentzian lineshape dips in the plots of reflectance vs. angle of incidence indicate the presence of the plasmon modes. The real and imaginary components of the propagation constraints (i.e., the propagation constant and loss coefficient) were calculated from the angular positions and widths of the ATR resonances recorded. Films of several thicknesses were probed. Results which support the theoretically predicted curves were reported.

  6. New techniques for producing thin boron films

    International Nuclear Information System (INIS)

    Thomas, G.E.

    1988-01-01

    A review will be presented of methods for producing thin boron films using an electron gun. Previous papers have had the problem of spattering of the boron source during the evaporation. Methods for reducing this problem will also be presented. 12 refs., 4 figs

  7. Intelligent Processing of Ferroelectric Thin Films

    Science.gov (United States)

    1994-05-31

    unsatisfactory. To detect the electroopic effects of thin films deposited on opaque substrates a waveguide refractometry of category 3 was reported. An advantage...of the waveguide refractometry is its capability of resolving the change in ordinary index from the change in the extraordinary index. Some successes

  8. Tailored piezoelectric thin films for energy harvester

    NARCIS (Netherlands)

    Wan, X.

    2013-01-01

    Piezoelectric materials are excellent materials to transfer mechanical energy into electrical energy, which can be stored and used to power other devices. PiezoMEMS is a good way to combine silicon wafer processing and piezoelectric thin film technology and lead to a variety of miniaturized and

  9. Amperometric Noise at Thin Film Band Electrodes

    DEFF Research Database (Denmark)

    Larsen, Simon T.; Heien, Michael L.; Taboryski, Rafael

    2012-01-01

    Background current noise is often a significant limitation when using constant-potential amperometry for biosensor application such as amperometric recordings of transmitter release from single cells through exocytosis. In this paper, we fabricated thin-film electrodes of gold and conductive...

  10. Stabilized thin film heterostructure for electrochemical applications

    DEFF Research Database (Denmark)

    2015-01-01

    The invention provides a method for the formation of a thin film multi-layered heterostructure upon a substrate, said method comprising the steps of: a. providing a substrate; b. depositing a buffer layer upon said substrate, said buffer layer being a layer of stable ionic conductor (B); c. depos...

  11. Reliability growth of thin film resistors contact

    Directory of Open Access Journals (Sweden)

    Lugin A. N.

    2010-10-01

    Full Text Available Necessity of resistive layer growth under the contact and in the contact zone of resistive element is shown in order to reduce peak values of current flow and power dissipation in the contact of thin film resistor, thereby to increase the resistor stability to parametric and catastrophic failures.

  12. Bilaterally Microstructured Thin Polydimethylsiloxane Film Production

    DEFF Research Database (Denmark)

    Vudayagiri, Sindhu; Yu, Liyun; Hassouneh, Suzan Sager

    2015-01-01

    Thin PDMS films with complex microstructures are used in the manufacturing of dielectric electro active polymer (DEAP) actuators, sensors and generators, to protect the metal electrode from large strains and to assure controlled actuation. The current manufacturing process at Danfoss Polypower A/...

  13. Flexible thin-film NFC tags

    NARCIS (Netherlands)

    Myny, K.; Tripathi, A.K.; Steen, J.L. van der; Cobb, B.

    2015-01-01

    Thin-film transistor technologies have great potential to become the key technology for leafnode Internet of Things by utilizing the NFC protocol as a communication medium. The main requirements are manufacturability on flexible substrates at a low cost while maintaining good device performance

  14. Magnetic surfaces, thin films, and multilayers

    International Nuclear Information System (INIS)

    Parkin, S.S.P.; Renard, J.P.; Shinjo, T.; Zinn, W.

    1992-01-01

    This paper details recent developments in the magnetism of surfaces, thin films and multilayers. More than 20 invited contributions and more than 60 contributed papers attest to the great interest and vitality of this subject. In recent years the study of magnetic surfaces, thin films and multilayers has undergone a renaissance, partly motivated by the development of new growth and characterization techniques, but perhaps more so by the discovery of many exciting new properties, some quite unanticipated. These include, most recently, the discovery of enormous values of magnetoresistance in magnetic multilayers far exceeding those found in magnetic single layer films and the discovery of oscillatory interlayer coupling in transition metal multilayers. These experimental studies have motivated much theoretical work. However these developments are to a large extent powered by materials engineering and our ability to control and understand the growth of thin layers just a few atoms thick. The preparation of single crystal thin film layers and multilayers remains important for many studies, in particular, for properties dependent. These studies obviously require engineering not just a layer thicknesses but of lateral dimensions as well. The properties of such structures are already proving to be a great interest

  15. Electrical characterization of thin film ferroelectric capacitors

    NARCIS (Netherlands)

    Tiggelman, M.P.J.; Reimann, K.; Klee, M.; Beelen, D.; Keur, W.; Schmitz, Jurriaan; Hueting, Raymond Josephus Engelbart

    2006-01-01

    Tunable capacitors can be used to facilitate the reduction of components in wireless technologies. The tunability of the capacitors is caused by the sensitivity of the relative dielectric constant to a change in polarization with electric field. Thin film ferroelectric MIM capacitors on silicon

  16. Internal stress control of boron thin film

    International Nuclear Information System (INIS)

    Satomi, N.; Kitamura, M.; Sasaki, T.; Nishikawa, M.

    1998-01-01

    The occurrence of stress in thin films has led to serious stability problems in practical use. We have investigated the stress in the boron films to find the deposition condition of the boron films with less stress. It was found that the stress in the boron film varies sufficiently from compressive to tensile stress, that is from -1.0 to 1.4 GPa, depending on the evaporation conditions, such as deposition rate and the substrate temperature. Hydrogen ion bombardment resulted in the enhancement of the compressive stress, possibly due to ion peening effect, while under helium ion bombardment, stress relief was observed. The boron film with nearly zero stress was obtained by the evaporation at a deposition rate of 0.5 nm s -1 and substrate temperature of 300 C. (orig.)

  17. Correlated dewetting patterns in thin polystyrene films

    CERN Document Server

    Neto, C; Seemann, R; Blossey, R; Becker, J; Grün, G

    2003-01-01

    We describe preliminary results of experiments and simulations concerned with the dewetting of thin polystyrene films (thickness < 7 nm) on top of silicon oxide wafers. In the experiments we scratched an initially flat film with an atomic force microscopy (AFM) tip, producing dry channels in the film. Dewetting of the films was imaged in situ using AFM and a correlated pattern of holes ('satellite holes') was observed along the rims bordering the channels. The development of this complex film rupture process was simulated and the results of experiments and simulations are in good agreement. On the basis of these results, we attempt to explain the appearance of satellite holes and their positions relative to pre-existing holes.

  18. Correlated dewetting patterns in thin polystyrene films

    International Nuclear Information System (INIS)

    Neto, Chiara; Jacobs, Karin; Seemann, Ralf; Blossey, Ralf; Becker, Juergen; Gruen, Guenther

    2003-01-01

    We describe preliminary results of experiments and simulations concerned with the dewetting of thin polystyrene films (thickness < 7 nm) on top of silicon oxide wafers. In the experiments we scratched an initially flat film with an atomic force microscopy (AFM) tip, producing dry channels in the film. Dewetting of the films was imaged in situ using AFM and a correlated pattern of holes ('satellite holes') was observed along the rims bordering the channels. The development of this complex film rupture process was simulated and the results of experiments and simulations are in good agreement. On the basis of these results, we attempt to explain the appearance of satellite holes and their positions relative to pre-existing holes

  19. Rim instability of bursting thin smectic films

    Science.gov (United States)

    Trittel, Torsten; John, Thomas; Tsuji, Kinko; Stannarius, Ralf

    2013-05-01

    The rupture of thin smectic bubbles is studied by means of high speed video imaging. Bubbles of centimeter diameter and film thicknesses in the nanometer range are pierced, and the instabilities of the moving rim around the opening hole are described. Scaling laws describe the relation between film thickness and features of the filamentation process of the rim. A flapping motion of the retracting smectic film is assumed as the origin of the observed filamentation instability. A comparison with similar phenomena in soap bubbles is made. The present experiments extend studies on soap films [H. Lhuissier and E. Villermaux, Phys. Rev. Lett. 103, 054501 (2009), 10.1103/PhysRevLett.103.054501] to much thinner, uniform films of thermotropic liquid crystals.

  20. Internal stress control of boron thin film

    Energy Technology Data Exchange (ETDEWEB)

    Satomi, N.; Kitamura, M.; Sasaki, T.; Nishikawa, M. [Osaka Univ., Suita (Japan). Graduate Sch. of Eng.

    1998-09-01

    The occurrence of stress in thin films has led to serious stability problems in practical use. We have investigated the stress in the boron films to find the deposition condition of the boron films with less stress. It was found that the stress in the boron film varies sufficiently from compressive to tensile stress, that is from -1.0 to 1.4 GPa, depending on the evaporation conditions, such as deposition rate and the substrate temperature. Hydrogen ion bombardment resulted in the enhancement of the compressive stress, possibly due to ion peening effect, while under helium ion bombardment, stress relief was observed. The boron film with nearly zero stress was obtained by the evaporation at a deposition rate of 0.5 nm s{sup -1} and substrate temperature of 300 C. (orig.) 12 refs.

  1. Dielectric loss of strontium titanate thin films

    Science.gov (United States)

    Dalberth, Mark Joseph

    1999-12-01

    Interest in strontium titanate (STO) thin films for microwave device applications continues to grow, fueled by the telecommunications industry's interest in phase shifters and tunable filters. The optimization of these devices depends upon increasing the phase or frequency tuning and decreasing the losses in the films. Currently, the dielectric response of thin film STO is poorly understood through lack of data and a theory to describe it. We have studied the growth of STO using pulsed laser deposition and single crystal substrates like lanthanum aluminate and neodymium gallate. We have researched ways to use ring resonators to accurately measure the dielectric response as a function of temperature, electric field, and frequency from low radio frequencies to a few gigahertz. Our films grown on lanthanum aluminate show marked frequency dispersion in the real part of the dielectric constant and hints of thermally activated loss behavior. We also found that films grown with conditions that optimized the dielectric constant showed increased losses. In an attempt to simplify the system, we developed a technique called epitaxial lift off, which has allowed us to study films removed from their growth substrates. These free standing films have low losses and show obvious thermally activated behavior. The "amount of tuning," as measured by a figure of merit, KE, is greater in these films than in the films still attached to their growth substrates. We have developed a theory that describes the real and imaginary parts of the dielectric constant. The theory models the real part using a mean field description of the ionic motion in the crystal and includes the loss by incorporating the motion of charged defects in the films.

  2. Thin film preparation of semiconducting iron pyrite

    Science.gov (United States)

    Smestad, Greg P.; Ennaoui, Ahmed; Fiechter, Sebastian; Hofmann, Wolfgang; Tributsch, Helmut; Kautek, Wolfgang

    1990-08-01

    Pyrite (Fe52) has been investigated as a promising new absorber material for thin film solar cell applications because of its high optical absorption coefficient of 1OL cm1, and its bandgap of 0.9 to 1.0 eV. Thin layers have been prepared by Metal Organic Chemical Vapor Deposition, MOCVD, Chemical Spray Pyrolysis, CSP, Chemical Vapor Transport, CVT, and Sulfurization of Iron Oxide films, 510. It is postulated that for the material FeS2, if x is not zero, a high point defect concentration results from replacing 2 dipoles by single S atoms. This causes the observed photovoltages and solar conversion efficiencies to be lower than expected. Using the Fe-O-S ternary phase diagram and the related activity plots, a thermodynamic understanding is formulated for the resulting composition of each of these types of films. It is found that by operating in the oxide portion of the phase diagram, the resulting oxidation state favors pyrite formation over FeS. By proper orientation of the grains relative to the film surface, and by control of pinholes and stoichiometry, an efficient thin film photovolatic solar cell material could be achieved.

  3. Tensile strain effect in ferroelectric perovskite oxide thin films on spinel magnesium aluminum oxide substrate

    Science.gov (United States)

    Zhou, Xiaolan

    Ferroelectrics are used in FeRAM (Ferroelectric random-access memory). Currently (Pb,Zr)TiO3 is the most common ferroelectric material. To get lead-free and high performance ferroelectric material, we investigated perovskite ferroelectric oxides (Ba,Sr)TiO3 and BiFeO3 films with strain. Compressive strain has been investigated intensively, but the effects of tensile strain on the perovskite films have yet to be explored. We have deposited (Ba,Sr)TiO3, BiFeO3 and related films by pulsed laser deposition (PLD) and analyzed the films by X-ray diffractometry (XRD), atomic force microscopy (AFM), etc. To obtain inherently fully strained films, the selection of the appropriate substrates is crucial. MgAl2O4 matches best with good quality and size, yet the spinel structure has an intrinsic incompatibility to that of perovskite. We introduced a rock-salt structure material (Ni 1-xAlxO1+delta) as a buffer layer to mediate the structural mismatch for (Ba,Sr)TiO3 films. With buffer layer Ni1-xAlxO1+delta, we show that the BST films have high quality crystallization and are coherently epitaxial. AFM images show that the films have smoother surfaces when including the buffer layer, indicating an inherent compatibility between BST-NAO and NAO-MAO. In-plane Ferroelectricity measurement shows double hysteresis loops, indicating an antiferroelectric-like behavior: pinned ferroelectric domains with antiparallel alignments of polarization. The Curie temperatures of the coherent fully strained BST films are also measured. It is higher than 900°C, at least 800°C higher than that of bulk. The improved Curie temperature makes the use of BST as FeRAM feasible. We found that the special behaviors of ferroelectricity including hysteresis loop and Curie temperature are due to inherent fully tensile strain. This might be a clue of physics inside ferroelectric stain engineering. An out-of-plane ferroelectricity measurement would provide a full whole story of the tensile strain. However, a

  4. Electrochemical fabrication of nanoporous polypyrrole thin films

    Energy Technology Data Exchange (ETDEWEB)

    Li Mei [Key Laboratory of Organic Optoelectronics and Molecular Engineering (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing, 100084 (China); Yuan Jinying [Key Laboratory of Organic Optoelectronics and Molecular Engineering (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing, 100084 (China)], E-mail: yuanjy@mail.tsinghua.edu.cn; Shi Gaoquan [Key Laboratory of Organic Optoelectronics and Molecular Engineering (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing, 100084 (China)], E-mail: gshi@mail.tsinghua.edu.cn

    2008-04-30

    Polypyrrole thin films with pores in nanometer scale were synthesized by direct electrochemical oxidation of pyrrole in a mixed electrolyte of isopropyl alcohol, boron trifluoride diethyl etherate, sodium dodecylsulfonate and poly(ethylene glycol) using well-aligned ZnO nanowires arrays as templates. The thin films exhibit high conductivity of ca. {sigma}{sub rt} {approx} 20.5 s/cm and can be driven to bend during redox processes in 1.0 M lithium perchlorate aqueous solution. The movement rate of an actuator based on this nanoporous film was measured to be over 90{sup o}/s at a driving potential of 0.8 V (vs. Ag/AgCl)

  5. Dynamics in thin folded polymer films

    Science.gov (United States)

    Croll, Andrew; Rozairo, Damith

    Origami and Kirigami inspired structures depend on a complex interplay between geometry and material properties. While clearly important to the overall function, very little attention has focused on how extreme curvatures and singularities in real materials influence the overall dynamic behaviour of folded structures. In this work we use a set of three polymer thin films in order to closely examine the interaction of material and geometry. Specifically, we use polydimethylsiloxane (PDMS), polystyrene (PS) and polycarbonate (PC) thin films which we subject to loading in several model geometries of varying complexity. Depending on the material, vastly different responses are noted in our experiments; D-cones can annihilate, cut or lead to a crumpling cascade when pushed through a film. Remarkably, order can be generated with additional perturbation. Finally, the role of adhesion in complex folded structures can be addressed. AFOSR under the Young Investigator Program (FA9550-15-1-0168).

  6. Magnon dispersion in thin magnetic films

    International Nuclear Information System (INIS)

    Balashov, T; Wulfhekel, W; Buczek, P; Sandratskii, L; Ernst, A

    2014-01-01

    Although the dispersion of magnons has been measured in many bulk materials, few studies deal with the changes in the dispersion when the material is in the form of a thin film, a system that is of interest for applications. Here we review inelastic tunneling spectroscopy studies of magnon dispersion in Mn/Cu 3 Au(1 0 0) and present new studies on Co and Ni thin films on Cu(1 0 0). The dispersion in Mn and Co films closely follows the dispersion of bulk samples with negligible dependence on thickness. The lifetime of magnons depends slightly on film thickness, and decreases considerably as the magnon energy increases. In Ni/Cu(1 0 0) films the thickness dependence of dispersion is much more pronounced. The measurements indicate a considerable mode softening for thinner films. Magnon lifetimes decrease dramatically near the edge of the Brillouin zone due to a close proximity of the Stoner continuum. The experimental study is supported by first-principles calculations. (paper)

  7. Magnon dispersion in thin magnetic films.

    Science.gov (United States)

    Balashov, T; Buczek, P; Sandratskii, L; Ernst, A; Wulfhekel, W

    2014-10-01

    Although the dispersion of magnons has been measured in many bulk materials, few studies deal with the changes in the dispersion when the material is in the form of a thin film, a system that is of interest for applications. Here we review inelastic tunneling spectroscopy studies of magnon dispersion in Mn/Cu3Au(1 0 0) and present new studies on Co and Ni thin films on Cu(1 0 0). The dispersion in Mn and Co films closely follows the dispersion of bulk samples with negligible dependence on thickness. The lifetime of magnons depends slightly on film thickness, and decreases considerably as the magnon energy increases. In Ni/Cu(1 0 0) films the thickness dependence of dispersion is much more pronounced. The measurements indicate a considerable mode softening for thinner films. Magnon lifetimes decrease dramatically near the edge of the Brillouin zone due to a close proximity of the Stoner continuum. The experimental study is supported by first-principles calculations.

  8. Function and application of ultra thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sasabe, Hiroyuki

    1988-02-01

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

  9. Thin film diamond microstructure applications

    Science.gov (United States)

    Roppel, T.; Ellis, C.; Ramesham, R.; Jaworske, D.; Baginski, M. E.; Lee, S. Y.

    1991-01-01

    Selective deposition and abrasion, as well as etching in atomic oxygen or reduced-pressure air, have been used to prepare patterned polycrystalline diamond films which, on further processing by anisotropic Si etching, yield the microstructures of such devices as flow sensors and accelerometers. Both types of sensor have been experimentally tested in the respective functions of hot-wire anemometer and both single- and double-hinged accelerometer.

  10. Thin film bismuth iron oxides useful for piezoelectric devices

    Science.gov (United States)

    Zeches, Robert J.; Martin, Lane W.; Ramesh, Ramamoorthy

    2016-05-31

    The present invention provides for a composition comprising a thin film of BiFeO.sub.3 having a thickness ranging from 20 nm to 300 nm, a first electrode in contact with the BiFeO.sub.3 thin film, and a second electrode in contact with the BiFeO.sub.3 thin film; wherein the first and second electrodes are in electrical communication. The composition is free or essentially free of lead (Pb). The BFO thin film is has the piezoelectric property of changing its volume and/or shape when an electric field is applied to the BFO thin film.

  11. Nanostructured thin film coatings with different strengthening effects

    Directory of Open Access Journals (Sweden)

    Panfilov Yury

    2017-01-01

    Full Text Available A number of articles on strengthening thin film coatings were analyzed and a lot of unusual strengthening effects, such as super high hardness and plasticity simultaneously, ultra low friction coefficient, high wear-resistance, curve rigidity increasing of drills with small diameter, associated with process formation of nanostructured coatings by the different thin film deposition methods were detected. Vacuum coater with RF magnetron sputtering system and ion-beam source and arc evaporator for nanostructured thin film coating manufacture are represented. Diamond Like Carbon and MoS2 thin film coatings, Ti, Al, Nb, Cr, nitride, carbide, and carbo-nitride thin film materials are described as strengthening coatings.

  12. Physical Vapor Deposition of Thin Films

    Science.gov (United States)

    Mahan, John E.

    2000-01-01

    A unified treatment of the theories, data, and technologies underlying physical vapor deposition methods With electronic, optical, and magnetic coating technologies increasingly dominating manufacturing in the high-tech industries, there is a growing need for expertise in physical vapor deposition of thin films. This important new work provides researchers and engineers in this field with the information they need to tackle thin film processes in the real world. Presenting a cohesive, thoroughly developed treatment of both fundamental and applied topics, Physical Vapor Deposition of Thin Films incorporates many critical results from across the literature as it imparts a working knowledge of a variety of present-day techniques. Numerous worked examples, extensive references, and more than 100 illustrations and photographs accompany coverage of: * Thermal evaporation, sputtering, and pulsed laser deposition techniques * Key theories and phenomena, including the kinetic theory of gases, adsorption and condensation, high-vacuum pumping dynamics, and sputtering discharges * Trends in sputter yield data and a new simplified collisional model of sputter yield for pure element targets * Quantitative models for film deposition rate, thickness profiles, and thermalization of the sputtered beam

  13. Flexible magnetic thin films and devices

    Science.gov (United States)

    Sheng, Ping; Wang, Baomin; Li, Runwei

    2018-01-01

    Flexible electronic devices are highly attractive for a variety of applications such as flexible circuit boards, solar cells, paper-like displays, and sensitive skin, due to their stretchable, biocompatible, light-weight, portable, and low cost properties. Due to magnetic devices being important parts of electronic devices, it is essential to study the magnetic properties of magnetic thin films and devices fabricated on flexible substrates. In this review, we mainly introduce the recent progress in flexible magnetic thin films and devices, including the study on the stress-dependent magnetic properties of magnetic thin films and devices, and controlling the properties of flexible magnetic films by stress-related multi-fields, and the design and fabrication of flexible magnetic devices. Project supported by the National Key R&D Program of China (No. 2016YFA0201102), the National Natural Science Foundation of China (Nos. 51571208, 51301191, 51525103, 11274321, 11474295, 51401230), the Youth Innovation Promotion Association of the Chinese Academy of Sciences (No. 2016270), the Key Research Program of the Chinese Academy of Sciences (No. KJZD-EW-M05), the Ningbo Major Project for Science and Technology (No. 2014B11011), the Ningbo Science and Technology Innovation Team (No. 2015B11001), and the Ningbo Natural Science Foundation (No. 2015A610110).

  14. Nanocomposite thin films for triggerable drug delivery.

    Science.gov (United States)

    Vannozzi, Lorenzo; Iacovacci, Veronica; Menciassi, Arianna; Ricotti, Leonardo

    2018-05-01

    Traditional drug release systems normally rely on a passive delivery of therapeutic compounds, which can be partially programmed, prior to injection or implantation, through variations in the material composition. With this strategy, the drug release kinetics cannot be remotely modified and thus adapted to changing therapeutic needs. To overcome this issue, drug delivery systems able to respond to external stimuli are highly desirable, as they allow a high level of temporal and spatial control over drug release kinetics, in an operator-dependent fashion. Areas covered: On-demand drug delivery systems actually represent a frontier in this field and are attracting an increasing interest at both research and industrial level. Stimuli-responsive thin films, enabled by nanofillers, hold a tremendous potential in the field of triggerable drug delivery systems. The inclusion of responsive elements in homogeneous or heterogeneous thin film-shaped polymeric matrices strengthens and/or adds intriguing properties to conventional (bare) materials in film shape. Expert opinion: This Expert Opinion review aims to discuss the approaches currently pursued to achieve an effective on-demand drug delivery, through nanocomposite thin films. Different triggering mechanisms allowing a fine control on drug delivery are described, together with current challenges and possible future applications in therapy and surgery.

  15. Optical thin films and coatings from materials to applications

    CERN Document Server

    Flory, Francois

    2013-01-01

    Optical coatings, including mirrors, anti-reflection coatings, beam splitters, and filters, are an integral part of most modern optical systems. This book provides an overview of thin film materials, the properties, design and manufacture of optical coatings and their use across a variety of application areas.$bOptical coatings, including mirrors, anti-reflection coatings, beam splitters, and filters, are an integral part of most modern optical systems. Optical thin films and coatings provides an overview of thin film materials, the properties, design and manufacture of optical coatings and their use across a variety of application areas. Part one explores the design and manufacture of optical coatings. Part two highlights unconventional features of optical thin films including scattering properties of random structures in thin films, optical properties of thin film materials at short wavelengths, thermal properties and colour effects. Part three focusses on novel materials for optical thin films and coatings...

  16. Temperature dependence of LRE-HRE-TM thin films

    Science.gov (United States)

    Li, Zuoyi; Cheng, Xiaomin; Lin, Gengqi; Li, Zhen; Huang, Zhixin; Jin, Fang; Wang, Xianran; Yang, Xiaofei

    2003-04-01

    Temperature dependence of the properties of RE-TM thin films is very important for MO recording. In this paper, we studied the temperature dependence of the magnetic and magneto-optical properties of the amorphous LRE-HRE-TM single layer thin films and LRE-HRE-TM/HRE-TM couple-bilayered thin films. For LRE-HRE-TM single layer thin films, the temperature dependence of the magnetization was investigated by using the mean field theory. The experimental and theoretical results matched very well. With the LRE substitution in HRE-TM thin film, the compensation temperature Tcomp decreased and the curie temperature Tc remained unchanged. Kerr rotation angle became larger and the saturation magnetization Ms at room temperature increased. For LRE-HRE-TM/HRE-TM couple-bilayered thin films, comparisons of the temperature dependences of the coercivities and Kerr rotation angles were made between isolated sublayers and couple-bilayered thin film.

  17. Application-related properties of giant magnetostrictive thin films

    International Nuclear Information System (INIS)

    Lim, S.H.; Kim, H.J.; Na, S.M.; Suh, S.J.

    2002-01-01

    In an effort to facilitate the utilization of giant magnetostrictive thin films in microdevices, application-related properties of these thin films, which include induced anisotropy, residual stress and corrosion properties, are investigated. A large induced anisotropy with an energy of 6x10 4 J/m 3 is formed in field-sputtered amorphous Sm-Fe-B thin films, resulting in a large magnetostriction anisotropy. Two components of residual stress, intrinsic compressive stress and tensile stress due to the difference of the thermal expansion coefficients between the substrate and thin film, are identified. The variation of residual stress with fabrication parameter and annealing temperature, and its influence on mechanical bending and magnetic properties are examined. Better corrosion properties are observed in Sm-Fe thin films than in Tb-Fe. Corrosion properties of Tb-Fe thin films, however, are much improved with the introduction of nitrogen to the thin films without deteriorating magnetostrictive properties

  18. In situ annealing of hydroxyapatite thin films

    International Nuclear Information System (INIS)

    Johnson, Shevon; Haluska, Michael; Narayan, Roger J.; Snyder, Robert L.

    2006-01-01

    Hydroxyapatite is a bioactive ceramic that mimics the mineral composition of natural bone. Unfortunately, problems with adhesion, poor mechanical integrity, and incomplete bone ingrowth limit the use of many conventional hydroxyapatite surfaces. In this work, we have developed a novel technique to produce crystalline hydroxyapatite thin films involving pulsed laser deposition and postdeposition annealing. Hydroxyapatite films were deposited on Ti-6Al-4V alloy and Si (100) using pulsed laser deposition, and annealed within a high temperature X-ray diffraction system. The transformation from amorphous to crystalline hydroxyapatite was observed at 340 deg. C. Mechanical and adhesive properties were examined using nanoindentation and scratch adhesion testing, respectively. Nanohardness and Young's modulus values of 3.48 and 91.24 GPa were realized in unannealed hydroxyapatite films. Unannealed and 350 deg. C annealed hydroxyapatite films exhibited excellent adhesion to Ti-6Al-4V alloy substrates. We anticipate that the adhesion and biological properties of crystalline hydroxyapatite thin films may be enhanced by further consideration of deposition and annealing parameters

  19. Thermal conductivities of thin, sputtered optical films

    International Nuclear Information System (INIS)

    Henager, C.H. Jr.; Pawlewicz, W.T.

    1991-05-01

    The normal component of the thin film thermal conductivity has been measured for the first time for several advanced sputtered optical materials. Included are data for single layers of boron nitride (BN), aluminum nitride (AIN), silicon aluminum nitride (Si-Al-N), silicon aluminum oxynitride (Si-Al-O-N), silicon carbide (SiC), and for dielectric-enhanced metal reflectors of the form Al(SiO 2 /Si 3 N 4 ) n and Al(Al 2 O 3 /AIN) n . Sputtered films of more conventional materials like SiO 2 , Al 2 O 3 , Ta 2 O 5 , Ti, and Si have also been measured. The data show that thin film thermal conductivities are typically 10 to 100 times lower than conductivities for the same materials in bulk form. Structural disorder in the amorphous or very fine-grained films appears to account for most of the conductivity difference. Conclusive evidence for a film/substrate interface contribution is presented

  20. Electromagnetic properties of thin film lead superconductors

    International Nuclear Information System (INIS)

    Moriyama, K.

    1978-01-01

    The dependence of critical film magnetic field H/sub cf/ on temperature, thickness, and surface texture of lead superconducting films was investigated, as well as the relationship between the applied magnetic field and the applied current at the critical field. Temperature and thickness dependence data were consistent with the predictions of London, of Ginzburg, and of Bardeen, Cooper, and Schreiffer. The values of H/sub cf/ of lead films deposited on a rough surface were consistently lower than for those on a smooth surface and so were not in agreement with any currently accepted theory. The degree of lowering of H/sub cf/ by a rough surface was greater in thin films than in thick films. The expected dependence of penetration depth lambda on thickness d was not observed, and the range of lambda was somewhat greater than expected. The range of coherence length was greater than predicted. The prediction for temperature dependence of critical current by Glover and Coffey was found to involve some oversimplification, and a suggested correction is supported by the data. For applied magnetic fields perpendicular to the applied current and parallel to the film surface, the relationship between the critical values of the magnetic field and the current was as predicted for lead films by Alphonse and Bergstein

  1. Structural phase transition and magnetic properties of Er-doped BiFeO3 nanoparticles

    International Nuclear Information System (INIS)

    Li, Y T; Zhang, H G; Dong, X G; Li, Q; Mao, W W; Dong, C L; Ren, S L; Li, X A; Wei, S Q

    2013-01-01

    The structural phase transition and local structural distortion of Er-doped BiFeO 3 nanoparticles have been discussed in order to understand the variation of magnetic properties in this system. The X-ray diffraction patterns and X-ray absorption fine structure of these samples demonstrate that there is structural phase transition and no obvious local structural distortion with the increasing of doping concentration. Unfortunately, no ferromagnetic properties have been observed even at a lower temperature. And the X-ray absorption spectra of Fe 2p core level of these samples are totally same, especially the energy positions do not shift which means the consistent valence states of Fe ions.

  2. Electric field control of magnetism using BiFeO3-based heterostructures

    International Nuclear Information System (INIS)

    Heron, J. T.; Schlom, D. G.; Ramesh, R.

    2014-01-01

    Conventional CMOS based logic and magnetic based data storage devices require the shuttling of electrons for data processing and storage. As these devices are scaled to increasingly smaller dimensions in the pursuit of speed and storage density, significant energy dissipation in the form of heat has become a center stage issue for the microelectronics industry. By taking advantage of the strong correlations between ferroic orders in multiferroics, specifically the coupling between ferroelectric and magnetic orders (magnetoelectricity), new device functionalities with ultra-low energy consumption can be envisioned. In this article, we review the advances and highlight challenges toward this goal with a particular focus on the room temperature magnetoelectric multiferroic, BiFeO 3 , exchange coupled to a ferromagnet. We summarize our understanding of the nature of exchange coupling and the mechanisms of the voltage control of ferromagnetism observed in these heterostructures

  3. Critical slowing down of spin fluctuations in BiFeO3

    International Nuclear Information System (INIS)

    Scott, J F; Singh, M K; Katiyar, R S

    2008-01-01

    In earlier work we reported the discovery of phase transitions in BiFeO 3 evidenced by divergences in the magnon light-scattering cross-sections at 140 and 201 K (Singh et al 2008 J. Phys.: Condens. Matter 20 252203) and fitted these intensity data to critical exponents α = 0.06 and α' = 0.10 (Scott et al 2008 J. Phys.: Condens. Matter 20 322203), under the assumption that the transitions are strongly magnetoelastic (Redfern et al 2008 at press) and couple to strain divergences through the Pippard relationship (Pippard 1956 Phil. Mag. 1 473). In the present paper we extend those criticality studies to examine the magnon linewidths, which exhibit critical slowing down (and hence linewidth narrowing) of spin fluctuations. The linewidth data near the two transitions are qualitatively different and we cannot reliably extract a critical exponent ν, although the mean field value ν = 1/2 gives a good fit near the lower transition.

  4. Tetragonal BiFeO3 on yttria-stabilized zirconia

    International Nuclear Information System (INIS)

    Liu, Heng-Jui; Du, Yu-Hao; Gao, Peng; Ikuhara, Yuichi; Huang, Yen-Chin; Chen, Yi-Chun; Chen, Hsiao-Wen; Liu, Hsiang-Lin; He, Qing; Chu, Ying-Hao

    2015-01-01

    High structural susceptibility of multiferroic BiFeO 3 (BFO) makes it a potential replacement of current Pb-based piezoelectrics. In this study, a tetragonal phase is identified based on a combination of x-ray diffraction, scanning transmission electronic microscopy, x-ray absorption spectroscopy, and Raman spectroscopy when BFO is grown on yttria-stabilized zirconia (YSZ) substrates. To distinguish the discrepancy between this tetragonal phase and common cases of monoclinic BFO, piezoelectric force microscopy images and optical property are also performed. It shows a lower electrostatic energy of ferroelectric domains and a large reduction of band gap for BFO grown on YSZ substrate comparing to the well-known one grown on LaAlO 3 substrate. Our findings in this work can provide more insights to understand the structural diversity of multiferroic BFO system for further applications

  5. Electric-field control of spin waves in multiferroic BiFeO3: Theory

    Science.gov (United States)

    de Sousa, Rogério; Rovillain, P.; Gallais, Y.; Sacuto, A.; Méasson, M. A.; Colson, D.; Forget, A.; Bibes, M.; Barthélémy, A.; Cazayous, M.

    2011-03-01

    Our recent experiment demonstrated gigantic (30%) electric-field tuning of magnon frequencies in multiferroic BiFeO3. We demonstrate that the origin of this effect is related to two linear magnetoelectric interactions that couple the component of electric field perpendicular to the ferroelectric vector to a quadratic form of the Néel vector. We calculate the magnon spectra due to each of these interactions and show that only one of them is consistent with experimental data. At high electric fields, this interaction induces a phase transition to a homogeneous state, and the multi-magnon spectra will fuse into two magnon frequencies. We discuss the possible microscopic mechanisms responsible for this novel interaction and the prospect for applications in magnonics. We acknowledge support from NSERC-Discovery (Canada) and the Agence Nationale pour la Recherche (France).

  6. Observation of room temperature saturated ferroelectric polarization in Dy substituted BiFeO3 ceramics

    KAUST Repository

    Zhang, Shuxia

    2012-04-06

    High quality Bi1− x Dy x FeO3 (0 ≤ x ≤ 0.15) ceramics have been fabricated by sintering Dy-doped BiFeO3 (BFO) precursor powders at a low temperature of 780 °C. The magnetic properties of BFO were improved by the introduction of Dy on the Bi-site. More importantly, well saturated ferroelectric hysteresis loops and polarization switching currents have been observed at room temperature. A large remnant polarization (2P r) value of 62 μC/cm2 is achieved, which is the highest value reported so far for rare-earth-doped BFO ceramics. Moreover, mechanisms for improved multiferroic properties depending on chemical doping-caused structure evolutions have also been discussed.

  7. Observation of room temperature saturated ferroelectric polarization in Dy substituted BiFeO3 ceramics

    KAUST Repository

    Zhang, Shuxia; Wang, Lei; Chen, Yao; Wang, Dongliang; Yao, Yingbang; Ma, Yanwei

    2012-01-01

    High quality Bi1− x Dy x FeO3 (0 ≤ x ≤ 0.15) ceramics have been fabricated by sintering Dy-doped BiFeO3 (BFO) precursor powders at a low temperature of 780 °C. The magnetic properties of BFO were improved by the introduction of Dy on the Bi-site. More importantly, well saturated ferroelectric hysteresis loops and polarization switching currents have been observed at room temperature. A large remnant polarization (2P r) value of 62 μC/cm2 is achieved, which is the highest value reported so far for rare-earth-doped BFO ceramics. Moreover, mechanisms for improved multiferroic properties depending on chemical doping-caused structure evolutions have also been discussed.

  8. Electrical conduction at domain walls in multiferroic BiFeO3

    Science.gov (United States)

    Seidel, Jan; Martin, Lane; He, Qing; Zhan, Qian; Chu, Ying-Hao; Rother, Axel; Hawkridge, Michael; Maksymovych, Peter; Yu, Pu; Gajek, Martin; Balke, Nina; Kalinin, Sergei; Gemming, Sybille; Wang, Feng; Catalán, Gustau; Scott, James; Spaldin, Nicola; Orenstein, Joseph; Ramesh, Ramamoorthy

    2009-03-01

    We report the observation of room temperature electronic conductivity at ferroelectric domain walls in BiFeO3. The origin and nature of the observed conductivity is probed using a combination of conductive atomic force microscopy, high resolution transmission electron microscopy and first-principles density functional computations. We show that a structurally driven change in both the electrostatic potential and local electronic structure (i.e., a decrease in band gap) at the domain wall leads to the observed electrical conductivity. We estimate the conductivity in the wall to be several orders of magnitude higher than for the bulk material. Additionally we demonstrate the potential for device applications of such conducting nanoscale features.

  9. Structural transitions and multiferroic properties of high Ni-doped BiFeO3

    Science.gov (United States)

    Betancourt-Cantera, L. G.; Bolarín-Miró, A. M.; Cortés-Escobedo, C. A.; Hernández-Cruz, L. E.; Sánchez-De Jesús, F.

    2018-06-01

    Nickel doped bismuth ferrite powders, BiFe1-x NixO3 (0 ≤ x ≤ 0.5), were synthesized by high-energy ball milling followed by an annealing at 700 °C. A detailed study about the substitution of Fe3+ by Ni2+ on the crystal structure and multiferroic properties is presented. The X-ray diffraction patterns reveal the formation of rhombohedral structure with small amounts of Bi2Fe4O9 as a secondary phase for x behavior indicates the frustration of the G-antiferromagnetic order typical of the un-doped BiFeO3, caused by the presence of small amounts of Ni2+ (x Behavior modifications of electrical conductivity, permittivity and dielectric loss versus frequency are related with crystal structure transformations, when nickel concentration is increased.

  10. Magnetic Field Control of Cycloidal Domains and Electric Polarization in Multiferroic BiFeO3

    Science.gov (United States)

    Bordács, S.; Farkas, D. G.; White, J. S.; Cubitt, R.; DeBeer-Schmitt, L.; Ito, T.; Kézsmárki, I.

    2018-04-01

    The magnetic field induced rearrangement of the cycloidal spin structure in ferroelectric monodomain single crystals of the room-temperature multiferroic BiFeO3 is studied using small-angle neutron scattering. The cycloid propagation vectors are observed to rotate when magnetic fields applied perpendicular to the rhombohedral (polar) axis exceed a pinning threshold value of ˜5 T . In light of these experimental results, a phenomenological model is proposed that captures the rearrangement of the cycloidal domains, and we revisit the microscopic origin of the magnetoelectric effect. A new coupling between the magnetic anisotropy and the polarization is proposed that explains the recently discovered magnetoelectric polarization perpendicular to the rhombohedral axis.

  11. 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.

  12. Domain switching of fatigued ferroelectric thin films

    Science.gov (United States)

    Tak Lim, Yun; Yeog Son, Jong; Shin, Young-Han

    2014-05-01

    We investigate the domain wall speed of a ferroelectric PbZr0.48Ti0.52O3 (PZT) thin film using an atomic force microscope incorporated with a mercury-probe system to control the degree of electrical fatigue. The depolarization field in the PZT thin film decreases with increasing the degree of electrical fatigue. We find that the wide-range activation field previously reported in ferroelectric domains result from the change of the depolarization field caused by the electrical fatigue. Domain wall speed exhibits universal behavior to the effective electric field (defined by an applied electric field minus the depolarization field), regardless of the degree of the electrical fatigue.

  13. Domain switching of fatigued ferroelectric thin films

    International Nuclear Information System (INIS)

    Tak Lim, Yun; Yeog Son, Jong; Shin, Young-Han

    2014-01-01

    We investigate the domain wall speed of a ferroelectric PbZr 0.48 Ti 0.52 O 3 (PZT) thin film using an atomic force microscope incorporated with a mercury-probe system to control the degree of electrical fatigue. The depolarization field in the PZT thin film decreases with increasing the degree of electrical fatigue. We find that the wide-range activation field previously reported in ferroelectric domains result from the change of the depolarization field caused by the electrical fatigue. Domain wall speed exhibits universal behavior to the effective electric field (defined by an applied electric field minus the depolarization field), regardless of the degree of the electrical fatigue

  14. Highly coercive thin-film nanostructures

    International Nuclear Information System (INIS)

    Zhou, J.; Skomski, R.; Kashyap, A.; Sorge, K.D.; Sui, Y.; Daniil, M.; Gao, L.; Yan, M.L.; Liou, S.-H.; Kirby, R.D.; Sellmyer, D.J.

    2005-01-01

    The processing, structure, and magnetism of highly coercive Sm-Co and FePt thin-film nanostructures are investigated. The structures include 1:5 based Sm-Co-Cu-Ti magnets, particulate FePt:C thin films, and FePt nanotubes. As in other systems, the coercivity depends on texture and imperfections, but there are some additional features. A specific coercivity mechanism in particulate media is a discrete pinning mode intermediate between Stoner-Wohlfarth rotation and ordinary domain-wall pinning. This mechanism yields a coercivity maximum for intermediate intergranular exchange and explains the occurrence of coercivities of 5 T in particulate Sm-Co-Cu-Ti magnets

  15. High efficiency thin-film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Schock, Hans-Werner [Helmholtz Zentrum Berlin (Germany). Solar Energy

    2012-11-01

    Production of photovoltaics is growing worldwide on a gigawatt scale. Among the thin film technologies, Cu(In,Ga)S,Se{sub 2} (CIS or CIGS) based solar cells have been the focus of more and more attention. This paper aims to analyze the success of CIGS based solar cells and the potential of this technology for future photovoltaics large-scale production. Specific material properties make CIS unique and allow the preparation of the material with a wide range of processing options. The huge potential lies in the possibility to take advantage of modern thin film processing equipment and combine it with very high efficiencies beyond 20% already achieved on the laboratory scale. A sustainable development of this technology could be realized by modifying the materials and replacing indium by abundant elements. (orig.)

  16. Quantifying clustering in disordered carbon thin films

    International Nuclear Information System (INIS)

    Carey, J.D.

    2006-01-01

    The quantification of disorder and the effects of clustering in the sp 2 phase of amorphous carbon thin films are discussed. The sp 2 phase is described in terms of disordered nanometer-sized conductive sp 2 clusters embedded in a less conductive sp 3 matrix. Quantification of the clustering of the sp 2 phase is estimated from optical as well as from electron and nuclear magnetic resonance methods. Unlike in other disordered group IV thin film semiconductors, we show that care must be exercised in attributing a meaning to the Urbach energy extracted from absorption measurements in the disordered carbon system. The influence of structural disorder, associated with sp 2 clusters of similar size, and topological disorder due to undistorted clusters of different sizes is also discussed. Extensions of this description to other systems are also presented

  17. Thin film photovoltaic panel and method

    Science.gov (United States)

    Ackerman, Bruce; Albright, Scot P.; Jordan, John F.

    1991-06-11

    A thin film photovoltaic panel includes a backcap for protecting the active components of the photovoltaic cells from adverse environmental elements. A spacing between the backcap and a top electrode layer is preferably filled with a desiccant to further reduce water vapor contamination of the environment surrounding the photovoltaic cells. The contamination of the spacing between the backcap and the cells may be further reduced by passing a selected gas through the spacing subsequent to sealing the backcap to the base of the photovoltaic panels, and once purged this spacing may be filled with an inert gas. The techniques of the present invention are preferably applied to thin film photovoltaic panels each formed from a plurality of photovoltaic cells arranged on a vitreous substrate. The stability of photovoltaic conversion efficiency remains relatively high during the life of the photovoltaic panel, and the cost of manufacturing highly efficient panels with such improved stability is significantly reduced.

  18. Strain quantification in epitaxial thin films

    International Nuclear Information System (INIS)

    Cushley, M

    2008-01-01

    Strain arising in epitaxial thin films can be beneficial in some cases but devastating in others. By altering the lattice parameters, strain may give a thin film properties hitherto unseen in the bulk material. On the other hand, heavily strained systems are prone to develop lattice defects in order to relieve the strain, which can cause device failure or, at least, a decrease in functionality. Using convergent beam electron diffraction (CBED) and high-resolution transmission electron microscopy (HRTEM), it is possible to determine local strains within a material. By comparing the results from CBED and HRTEM experiments, it is possible to gain a complete view of a material, including the strain and any lattice defects present. As well as looking at how the two experimental techniques differ from each other, I will also look at how results from different image analysis algorithms compare. Strain in Si/SiGe samples and BST/SRO/MgO capacitor structures will be discussed.

  19. Method of formation of thin film component

    Energy Technology Data Exchange (ETDEWEB)

    Wada, Chikara; Kato, Kinya

    1988-04-16

    In the production process of component which is carrying thin film device, such as thin film transistor, acid treatment is applied for etching or for preventing contamination. In case of barium borsilicate glass base, the base is affected by the acid treatment resulting the decrease of transparency. To avoid the effect, deposition of SiO/sub 2/ layer on the surface of the base is usually applied. This invention relates to the protective method of barium borosilicate surface by harnessing the effect of coexisting ion in the acid treatment bath. The method is to add 0.03-5 mol/l of phosphoric acid or its salt in the bath. By the effect of coexisting ion, barium borsilicate glass surface was protected from the damage. (2 figs)

  20. Structural, magnetic and dielectric properties of Pr-modified BiFeO3 multiferroic

    International Nuclear Information System (INIS)

    Varshney, Dinesh; Sharma, Poorva; Satapathy, S.; Gupta, P.K.

    2014-01-01

    Graphical abstract: -- Highlights: • BFO and Bi 0.95 Pr 0.05 FeO 3 prepared successfully via solid state reaction route. • XRD confirms rhombohedral structure with space group R3c. • Relaxation process is attributed to thermal motion and hopping of V O 2+ . • Magnetization is enhanced in Bi 0.95 Pr 0.05 FeO 3 sample. • Enhanced magnetization stem from suppression of the spiral spin modulation. -- Abstract: The structural, vibrational, magnetic and dielectric properties of polycrystalline BiFeO 3 and Bi 0.95 Pr 0.05 FeO 3 are investigated by combining X-ray diffraction, Raman scattering spectra, magnetometry and dielectric measurements. Structural symmetry with rhombohedral R3c phase is revealed for both parent and 5% Pr substitution at Bi site, serving no chemical pressure and causes no structural transition from R3c to any other phase is identified from X-ray diffraction patterns and Raman scattering spectra. The shifting of phonon modes towards higher frequency side is attributed to lower atomic mass of Pr ion as compared to Bi ion. The magnetic measurements at room temperature indicate that Pr substitution induces ferromagnetism and discerns large and non-zero remnant magnetization as compare to pristine BiFeO 3 . Both dielectric permittivity and loss factor of Bi 0.95 Pr 0.05 FeO 3 strongly decreases with increased frequency. Significant role of hopping of oxygen ion vacancies in Bi 0.95 Pr 0.05 FeO 3 is inferred from modulus spectra and ac conductivity analysis

  1. Thin film solar cell technology in Germany

    International Nuclear Information System (INIS)

    Diehl, W.; Sittinger, V.; Szyszka, B.

    2005-01-01

    Within the scope of limited nonrenewable energy resources and the limited capacity of the ecosystem for greenhouse gases and nuclear waste, sustainability is one important target in the future. Different energy scenarios showed the huge potential for photovoltaics (PV) to solve this energy problem. Nevertheless, in the last decade, PV had an average growth rate of over 20% per year. In 2002, the solar industry delivered more than 500 MWp/year of photovoltaic generators [A. Jaeger-Waldau, A European Roadmap for PV R and D, E-MRS Spring Meeting, (2003)]. More than 85% of the current production involves crystalline silicon technologies. These technologies still have a high cost reduction potential, but this will be limited by the silicon feedstock. On the other hand the so-called second generation thin film solar cells based on a-Si, Cu(In,Ga)(Se,S 2 (CIGS) or CdTe have material thicknesses of a few microns as a result of their direct band gap. Also, the possibility of circuit integration offers an additional cost reduction potential. Especially in Germany, there are a few companies who focus on thin film solar cells. Today, there are two manufacturers with production lines: the Phototronics (PST) division of RWE-Schott Solar with a-Si thin film technology and the former Antec Solar GmbH (now Antec Solar Energy GmbH) featuring the CdTe technology. A pilot line based on CIGS technology is run by Wuerth Solar GmbH. There is also a variety of research activity at other companies, namely, at Shell Solar, Sulfurcell Solartechnik GmbH, Solarion GmbH and the CIS-Solartechnik GmbH. We will give an overview on research activity on various thin film technologies, as well as different manufacturing and production processes in the companies mentioned above. (Author)

  2. Optical characterization of thin solid films

    CERN Document Server

    Ohlídal, Miloslav

    2018-01-01

    This book is an up-to-date survey of the major optical characterization techniques for thin solid films. Emphasis is placed on practicability of the various approaches. Relevant fundamentals are briefly reviewed before demonstrating the application of these techniques to practically relevant research and development topics. The book is written by international top experts, all of whom are involved in industrial research and development projects.

  3. Thin-film silicon solar cell technology

    Czech Academy of Sciences Publication Activity Database

    Shah, A. V.; Schade, H.; Vaněček, Milan; Meier, J.; Vallat-Sauvain, E.; Wyrsch, N.; Kroll, U.; Droz, C.; Bailat, J.

    2004-01-01

    Roč. 12, - (2004), s. 113-142 ISSN 1062-7995 R&D Projects: GA MŽP SN/320/11/03 Institutional research plan: CEZ:AV0Z1010914 Keywords : thin-film silicon modules * hydrogenerated amorphous silicon(a-Si:H) * hydrogenerated microcrystalline (ćc-Si:H) * transparent conductive oxydes(TCOs) * building-integrated photovoltaics(BIPV) Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.196, year: 2004

  4. The carbonization of thin polyaniline films

    Czech Academy of Sciences Publication Activity Database

    Morávková, Zuzana; Trchová, Miroslava; Exnerová, Milena; Stejskal, Jaroslav

    2012-01-01

    Roč. 520, č. 19 (2012), s. 6088-6094 ISSN 0040-6090 R&D Projects: GA AV ČR IAA400500905; GA AV ČR IAA100500902; GA ČR GAP205/12/0911 Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : polyaniline * thin films * infrared spectroscopy Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.604, year: 2012

  5. Study of obliquely deposited thin cobalt films

    International Nuclear Information System (INIS)

    Szmaja, W.; Kozlowski, W.; Balcerski, J.; Kowalczyk, P.J.; Grobelny, J.; Cichomski, M.

    2010-01-01

    Research highlights: → The paper reports simultaneously on the magnetic domain structure of obliquely deposited thin cobalt films (40 nm and 100 nm thick) and their morphological structure. Such studies are in fact rare (Refs. cited in the paper). → Moreover, to our knowledge, observations of the morphological structure of these films have not yet been carried out simultaneously by transmission electron microscopy (TEM) and atomic force microscopy (AFM). → The films of both thicknesses were found to have uniaxial in-plane magnetic anisotropy. → The magnetic microstructure of the films 40 nm thick was composed of domains running and magnetized predominantly in the direction perpendicular to the incidence plane of the vapor beam. → As the film thickness was changed from 40 nm to 100 nm, the magnetic anisotropy was observed to change from the direction perpendicular to parallel with respect to the incidence plane. → Thanks to the application of TEM and AFM, complementary information on the morphological structure of the films could be obtained. → In comparison with TEM images, AFM images revealed grains larger in size and slightly elongated in the direction perpendicular rather than parallel to the incidence plane. → These experimental findings clearly show that surface diffusion plays an important role in the process of film growth. → For the films 40 nm thick, the alignment of columnar grains in the direction perpendicular to the incidence plane was observed. → This correlates well with the magnetic domain structure of these films. → For the films 100 nm thick, the perpendicular alignment of columnar grains could also be found, although in fact with larger difficulty. → TEM studies showed that the films consisted mainly of the hexagonal close-packed (HCP) crystalline structure, but no preferred crystallographic orientation of the grains could be detected for the films of both thicknesses. → For the films 100 nm thick, the alignment of

  6. P-type CuxS thin films: Integration in a thin film transistor structure

    International Nuclear Information System (INIS)

    Nunes de Carvalho, C.; Parreira, P.; Lavareda, G.; Brogueira, P.; Amaral, A.

    2013-01-01

    Cu x S thin films, 80 nm thick, are deposited by vacuum thermal evaporation of sulfur-rich powder mixture, Cu 2 S:S (50:50 wt.%) with no intentional heating of the substrate. The process of deposition occurs at very low deposition rates (0.1–0.3 nm/s) to avoid the formation of Cu or S-rich films. The evolution of Cu x S films surface properties (morphology/roughness) under post deposition mild annealing in air at 270 °C and their integration in a thin film transistor (TFT) are the main objectives of this study. Accordingly, Scanning Electron Microscopy studies show Cu x S films with different surface morphologies, depending on the post deposition annealing conditions. For the shortest annealing time, the Cu x S films look to be constructed of grains with large dimension at the surface (approximately 100 nm) and consequently, irregular shape. For the longest annealing time, films with a fine-grained surface are found, with some randomly distributed large particles bound to this fine-grained surface. Atomic Force Microscopy results indicate an increase of the root-mean-square roughness of Cu x S surface with annealing time, from 13.6 up to 37.4 nm, for 255 and 345 s, respectively. The preliminary integration of Cu x S films in a TFT bottom-gate type structure allowed the study of the feasibility and compatibility of this material with the remaining stages of a TFT fabrication as well as the determination of the p-type characteristic of the Cu x S material. - Highlights: • Surface properties of annealed Cu x S films. • Variation of conductivity with annealing temperatures of Cu x S films. • Application of evaporated Cu x S films in a thin film transistor (TFT) structure. • Determination of Cu x S p-type characteristic from TFT behaviour

  7. Neutron reflectivity of electrodeposited thin magnetic films

    International Nuclear Information System (INIS)

    Cooper, Joshaniel F.K.; Vyas, Kunal N.; Steinke, Nina-J.; Love, David M.; Kinane, Christian J.; Barnes, Crispin H.W.

    2014-01-01

    Highlights: • Electrodeposited magnetic bi-layers were measured by polarised neutron reflectivity. • When growing a CoNiCu alloy from a single bath a Cu rich region is initially formed. • This Cu rich region is formed in the first layer but not subsequent ones. • Ni deposition is inhibited in thin film growth and Co deposits anomalously. • Alloy magnetism and neutron scattering length give a self-consistent model. - Abstract: We present a polarised neutron reflectivity (PNR) study of magnetic/non-magnetic (CoNiCu/Cu) thin films grown by single bath electrodeposition. We find that the composition is neither homogeneous with time, nor consistent with bulk values. Instead an initial, non-magnetic copper rich layer is formed, around 2 nm thick. This layer is formed by the deposition of the dilute, but rapidly diffusing, Cu 2+ ions near the electrode surface at the start of growth, before the region is depleted and the deposition becomes mass transport limited. After the region has been depleted, by growth etc., this layer does not form and thus may be prevented by growing a copper buffer layer immediately preceding the magnetic layer growth. As has been previously found, cobalt deposits anomalously compared to nickel, and even inhibits Ni deposition in thin films. The layer magnetisation and average neutron scattering length are fitted independently but both depend upon the alloy composition. Thus these parameters can be used to check for model self-consistency, increasing confidence in the derived composition

  8. Preventing Thin Film Dewetting via Graphene Capping.

    Science.gov (United States)

    Cao, Peigen; Bai, Peter; Omrani, Arash A; Xiao, Yihan; Meaker, Kacey L; Tsai, Hsin-Zon; Yan, Aiming; Jung, Han Sae; Khajeh, Ramin; Rodgers, Griffin F; Kim, Youngkyou; Aikawa, Andrew S; Kolaczkowski, Mattew A; Liu, Yi; Zettl, Alex; Xu, Ke; Crommie, Michael F; Xu, Ting

    2017-09-01

    A monolayer 2D capping layer with high Young's modulus is shown to be able to effectively suppress the dewetting of underlying thin films of small organic semiconductor molecule, polymer, and polycrystalline metal, respectively. To verify the universality of this capping layer approach, the dewetting experiments are performed for single-layer graphene transferred onto polystyrene (PS), semiconducting thienoazacoronene (EH-TAC), gold, and also MoS 2 on PS. Thermodynamic modeling indicates that the exceptionally high Young's modulus and surface conformity of 2D capping layers such as graphene and MoS 2 substantially suppress surface fluctuations and thus dewetting. As long as the uncovered area is smaller than the fluctuation wavelength of the thin film in a dewetting process via spinodal decomposition, the dewetting should be suppressed. The 2D monolayer-capping approach opens up exciting new possibilities to enhance the thermal stability and expands the processing parameters for thin film materials without significantly altering their physical properties. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Aluminum nitride and nanodiamond thin film microstructures

    Energy Technology Data Exchange (ETDEWEB)

    Knoebber, Fabian; Bludau, Oliver; Roehlig, Claus-Christian; Williams, Oliver; Sah, Ram Ekwal; Kirste, Lutz; Cimalla, Volker; Lebedev, Vadim; Nebel, Christoph; Ambacher, Oliver [Fraunhofer-Institute for Applied Solid State Physics, Freiburg (Germany)

    2010-07-01

    In this work, aluminum nitride (AlN) and nanocrystalline diamond (NCD) thin film microstructures have been developed. Freestanding NCD membranes were coated with a piezoelectrical AlN layer in order to build tunable micro-lens arrays. For the evaluation of the single material quality, AlN and NCD thin films on silicon substrates were fabricated using RF magnetron sputtering and microwave chemical vapor deposition techniques, respectively. The crystal quality of AlN was investigated by X-ray diffraction. The piezoelectric constant d{sub 33} was determined by scanning laser vibrometry. The NCD thin films were optimized with respect to surface roughness, mechanical stability, intrinsic stress and transparency. To determine the mechanical properties of the materials, both, micromechanical resonator and membrane structures were fabricated and measured by magnetomotive resonant frequency spectroscopy and bulging experiments, respectively. Finally, the behavior of AlN/NCD heterostructures was modeled using the finite element method and the first structures were characterized by piezoelectrical measurements.

  10. Process for forming thin film, heat treatment process of thin film sheet, and heat treatment apparatus therefor

    International Nuclear Information System (INIS)

    Watanabe, S.

    1984-01-01

    The invention provides a process for forming a magnetic thin film on a base film, a heat treatment process of a thin film sheet consisting of the base film and the magnetic thin film, and an apparatus for performing heat treatment of the thin film sheet. Tension applied to the thin film sheet is substantially equal to that applied to the base film when the magnetic thin film is formed thereon. Then, the thin film sheet is treated with heat. The thin film sheet is heated with a given temperature gradient to a reactive temperature at which heat shrinkage occurs, while the tension is being applied thereto. Thereafter, the thin film sheet to which the tension is still applied is cooled with substantially the same temperature gradient as applied in heating. The heat treatment apparatus has a film driving unit including a supply reel, a take-up reel, a drive source and guide rollers; a heating unit including heating plates, heater blocks and a temperature controller for heating the sheet to the reactive temperature; and a heat insulating unit including a thermostat and another temperature controller for maintaining the sheet at the nonreactive temperature which is slightly lower than the reactive temperature

  11. Collective Behavior of Amoebae in Thin Films

    Science.gov (United States)

    Bae, Albert

    2005-03-01

    We have discovered new aspects of social behavior in Dictyostelium discoideum by culturing high density colonies in liquid media depleted of nutrients in confined geometries by using three different preparations: I. thin (15-40um thick) and II. ultrathin (behavior of cells despite flattening that increased their areas by over an order of magnitude. We also observed that the earliest synchronized response of cells following the onset of starvation, a precursor to aggregation, was hastened by reducing the thickness of the aqueous culture layer. We were surprised to find that the threshold concentration for aggregation was raised by thin film confinement when compared to bulk behavior. Finally, both the ultra thin and microfluidic preparations reveal, with new clarity, vortex states of aggregation.

  12. Effect of surface modification of BiFeO3 on the dielectric, ferroelectric, magneto-dielectric properties of polyvinylacetate/BiFeO3 nanocomposites

    Directory of Open Access Journals (Sweden)

    O. P. Bajpai

    2014-09-01

    Full Text Available Bismuth ferrite (BiFeO3 is considered as one of the most promising materials in the field of multiferroics. In this work, a simple green route as well as synthetic routes has been used for the preparation of pure phase BiFeO3. An extract of Calotropis Gigantea flower was used as a reaction medium in green route. In each case so formed BiFeO3 particles are of comparable quality. These particles are in the range of 50–60 nm and exhibit mixed morphology (viz., spherical and cubic as confirmed by TEM analysis. These pure phase BiFeO3 nanoparticles were first time surface modified effectively by mean of two silylating agent’s viz., tetraethyl orthosilicate (TEOS and (3-Aminopropyltriethoxysilane (APTES. Modified and unmodified BiFeO3 nanoparticles were efficiently introduced into polyvinylacetate (PVAc matrix. It has been shown that nanocomposite prepared by modified BiFeO3 comprise superior dispersion characteristics, improved ferroelectric properties and favorable magneto-dielectric properties along with excellent wettability in compare to nanocomposite prepared by unmodified BiFeO3. These preliminary results demonstrate possible applications of this type of nanocomposites particularly in the field of multiferroic coating and adhesives.

  13. Ion beam deposited epitaxial thin silicon films

    International Nuclear Information System (INIS)

    Orrman-Rossiter, K.G.; Al-Bayati, A.H.; Armour, D.G.; Donnelly, S.E.; Berg, J.A. van den

    1991-01-01

    Deposition of thin films using low energy, mass-separated ion beams is a potentially important low temperature method of producing epitaxial layers. In these experiments silicon films were grown on Si (001) substrates using 10-200 eV 28 Si + and 30 Si + ions at substrate temperatures in the range 273-1073 K, under ultrahigh-vacuum conditions (deposition pressure -7 Pa). The film crystallinity was assessed in situ using medium energy ion scattering (MEIS). Films of crystallinity comparable to bulk samples were grown using 10-40 eV 28 Si + and 30 Si + ions at deposition temperatures in the range 623-823 K. These experiments confirmed the role of key experimental parameters such as ion energy, substrate temperature during deposition, and the surface treatment prior to deposition. It was found that a high temperature in situ anneal (1350-1450 K) gave the best results for epitaxial nucleation, whereas low energy (20-40 eV) Cl + ion bombardment resulted in amorphous film growth. The deposition energy for good epitaxial growth indicates that it is necessary to provide enough energy to induce local mobility but not to cause atomic displacements leading to the buildup of stable defects, e.g. divacancies, below the surface layer of the growing film. (orig.)

  14. Infrared characterization of strontium titanate thin films

    International Nuclear Information System (INIS)

    Almeida, B.G.; Pietka, A.; Mendes, J.A.

    2004-01-01

    Strontium titanate thin films have been prepared at different oxygen pressures with various post-deposition annealing treatments. The films were deposited by pulsed laser ablation at room temperature on Si(0 0 1) substrates with a silica buffer layer. Infrared reflectance measurements were performed in order to determine relevant film parameters such as layer thicknesses and chemical composition. The infrared reflectance spectra were fitted by using adequate dielectric function forms for each layer. The fitting procedure provided the extraction of the dielectric functions of the strontium titanate film, the silica layer and the substrate. The as-deposited films are found to be amorphous, and their infrared spectra present peaks corresponding to modes with high damping constants. As the annealing time and temperature increases the strontium titanate layer becomes more ordered so that it can be described by its SrTiO 3 bulk mode parameters. Also, the silica layer grows along with the ordering of the strontium titanate film, due to oxidation during annealing

  15. 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.

  16. Thermal decomposition of titanium deuteride thin films

    International Nuclear Information System (INIS)

    Malinowski, M.E.

    1983-01-01

    The thermal desorption spectra of deuterium from essentially clean titanium deuteride thin films were measured by ramp heating the films in vacuum; the film thicknesses ranged from 20 to 220 nm and the ramp rates varied from 0.5 to about 3 0 C s - 1 . Each desorption spectrum consisted of a low nearly constant rate at low temperatures followed by a highly peaked rate at higher temperatures. The cleanliness and thinness of the films permitted a description of desorption rates in terms of a simple phenomenological model based on detailed balancing in which the low temperature pressure-composition characteristics of the two-phase (α-(α+#betta#)-#betta#) region of the Ti-D system were used as input data. At temperatures below 340 0 C the model predictions were in excellent agreement with the experimentally measured desorption spectra. Interpretations of the spectra in terms of 'decomposition trajectories'' are possible using this model, and this approach is also used to explain deviations of the spectra from the model at temperatures of 340 0 C and above. (Auth.)

  17. Electrical resistivity of thin metal films

    CERN Document Server

    Wissmann, Peter

    2007-01-01

    The aim of the book is to give an actual survey on the resistivity of thin metal and semiconductor films interacting with gases. We discuss the influence of the substrate material and the annealing treatment of the films, presenting our experimental data as well as theoretical models to calculate the scattering cross section of the conduction electrons in the frame-work of the scattering hypothesis. Main emphasis is laid on the comparison of gold and silver films which exhibit nearly the same lattice structure but differ in their chemical activity. In conclusion, the most important quantity for the interpretation is the surface charging z while the correlation with the optical data or the frustrated IR vibrations seems the show a more material-specific character. Z can be calculated on the basis of the density functional formalism or the self-consistent field approximation using Mulliken’s population analysis.

  18. Sulfated cellulose thin films with antithrombin affinity

    Directory of Open Access Journals (Sweden)

    2009-11-01

    Full Text Available Cellulose thin films were chemically modified by in situ sulfation to produce surfaces with anticoagulant characteristics. Two celluloses differing in their degree of polymerization (DP: CEL I (DP 215–240 and CEL II (DP 1300–1400 were tethered to maleic anhydride copolymer (MA layers and subsequently exposed to SO3•NMe3 solutions at elevated temperature. The impact of the resulting sulfation on the physicochemical properties of the cellulose films was investigated with respect to film thickness, atomic composition, wettability and roughness. The sulfation was optimized to gain a maximal surface concentration of sulfate groups. The scavenging of antithrombin (AT by the surfaces was determined to conclude on their potential anticoagulant properties.

  19. Preparation and properties of antimony thin film anode materials

    Institute of Scientific and Technical Information of China (English)

    SU Shufa; CAO Gaoshao; ZHAO Xinbing

    2004-01-01

    Metallic antimony thin films were deposited by magnetron sputtering and electrodeposition. Electrochemical properties of the thin film as anode materials for lithium-ion batteries were investigated and compared with those of antimony powder. It was found that both magnetron sputtering and electrodeposition are easily controllable processes to deposit antimony films with fiat charge/discharge potential plateaus. The electrochemical performances of antimony thin films, especially those prepared with magnetron sputtering, are better than those of antimony powder. The reversible capacities of the magnetron sputtered antimony thin film are above 400 mA h g-1 in the first 15 cycles.

  20. Structural characterization of vacuum evaporated ZnSe thin films

    Indian Academy of Sciences (India)

    The lattice parameter, grain size, average internal stress, microstrain, dislocation density and degree of pre- ferred orientation in the film are calculated and correlated with Ts. Keywords. ZnSe thin films; X-ray diffraction; average internal stress; microstrain; dislocation density. 1. Introduction. Thin films of ZnSe has attracted ...

  1. Scanning tunneling spectroscopy of Pb thin films

    Energy Technology Data Exchange (ETDEWEB)

    Becker, Michael

    2010-12-13

    The present thesis deals with the electronic structure, work function and single-atom contact conductance of Pb thin films, investigated with a low-temperature scanning tunneling microscope. The electronic structure of Pb(111) thin films on Ag(111) surfaces is investigated using scanning tunneling spectroscopy (STS). Quantum size effects, in particular, quantum well states (QWSs), play a crucial role in the electronic and physical properties of these films. Quantitative analysis of the spectra yields the QWS energies as a function of film thickness, the Pb bulk-band dispersion in {gamma}-L direction, scattering phase shifts at the Pb/Ag interface and vacuum barrier as well as the lifetime broadening at anti {gamma}. The work function {phi} is an important property of surfaces, which influences catalytic reactivity and charge injection at interfaces. It controls the availability of charge carriers in front of a surface. Modifying {phi} has been achieved by deposition of metals and molecules. For investigating {phi} at the atomic scale, scanning tunneling microscopy (STM) has become a widely used technique. STM measures an apparent barrier height {phi}{sub a}, which is commonly related to the sample work function {phi}{sub s} by: {phi}{sub a}=({phi}{sub s}+{phi}{sub t}- vertical stroke eV vertical stroke)/2, with {phi}{sub t} the work function of the tunneling tip, V the applied tunneling bias voltage, and -e the electron charge. Hence, the effect of the finite voltage in STM on {phi}{sub a} is assumed to be linear and the comparison of {phi}{sub a} measured at different surface sites is assumed to yield quantitative information about work function differences. Here, the dependence of {phi}{sub a} on the Pb film thickness and applied bias voltage V is investigated. {phi}{sub a} is found to vary significantly with V. This bias dependence leads to drastic changes and even inversion of contrast in spatial maps of {phi}{sub a}, which are related to the QWSs in the Pb

  2. Preparation and characterization of vanadium oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Monfort, O.; Plesch, G. [Comenius University of Bratislava, Faculty of Natural Sciences, Department of Inorganic Chemistry, 84215 Bratislava (Slovakia); Roch, T. [Comenius University of Bratislava, Faculty of Mathematics Physics and Informatics, Department of Experimental Physics, 84248 Bratislava (Slovakia)

    2013-04-16

    The thermotropic VO{sub 2} films have many applications, since they exhibit semiconductor-conductor switching properties at temperature around 70 grad C. Vanadium oxide thin films were prepared via sol-gel method. Spin coater was used to depose these films on Si/SiO{sub 2} and lime glass substrates. Thin films of V{sub 2}O{sub 5} can be reduced to metastable VO{sub 2} thin films at the temperature of 450 grad C under the pressure of 10{sup -2} Pa. These films are then converted to thermotropic VO{sub 2} at 700 grad C in argon under normal pressure. (authors)

  3. Thin film structures and phase stability

    International Nuclear Information System (INIS)

    Clemens, B.M.; Johnson, W.L.

    1990-01-01

    This was a two day symposium, with invited and contributed papers as well as an evening poster session. The first day concentrated on solid state reactions with invited talks by Lindsay Greer from the University of Cambridge, King Tu from IBM Yorktown Heights, and Carl Thompson from MIT. Professor Greer observed that the diffusion of Zr is 10 6 times slower than that of Ni in amorphous NiZr, confirming that Ni is the mobile species in solid state amorphization. King Tu explained the formation of metastable phases in this film diffusion couples by the concept of maximum rate of free energy change. Carl Thompson discussed the formation of amorphous phases in metal silicon systems, and discussed a two stage nucleation and growth process. The contributed papers also generated discussion on topics such as phase segregation, amorphous silicide formation, room temperature oxidation of silicon, and nucleation during ion beam irradiation. There was a lively poster session on Monday evening with papers on a wide variety of topics covering the general area of thin film science. The second day had sessions Epitaxy and Multilayer Structure I and II, with the morning focussing on epitaxial and heteroepitaxial growth of thin films. Robin Farrow of IBM Almaden led off with an invited talk where he reported on some remarkable success he and his co-workers have had in growing single crystal epitaxial thin films and superlattices of silver, iron, cobalt and platinum on GaAs. This was followed by several talks on epitaxial growth and characterization. The afternoon focused on interfaces and structure of multilayered materials. A session on possible stress origins of the supermodulus effect was highlighted by lively interaction from the audience. Most of the papers presented at the symposium are presented in this book

  4. Self-Limited Growth in Pentacene Thin Films.

    Science.gov (United States)

    Pachmajer, Stefan; Jones, Andrew O F; Truger, Magdalena; Röthel, Christian; Salzmann, Ingo; Werzer, Oliver; Resel, Roland

    2017-04-05

    Pentacene is one of the most studied organic semiconducting materials. While many aspects of the film formation have already been identified in very thin films, this study provides new insight into the transition from the metastable thin-film phase to bulk phase polymorphs. This study focuses on the growth behavior of pentacene within thin films as a function of film thickness ranging from 20 to 300 nm. By employing various X-ray diffraction methods, combined with supporting atomic force microscopy investigations, one crystalline orientation for the thin-film phase is observed, while three differently tilted bulk phase orientations are found. First, bulk phase crystallites grow with their 00L planes parallel to the substrate surface; second, however, crystallites tilted by 0.75° with respect to the substrate are found, which clearly dominate the former in ratio; third, a different bulk phase polymorph with crystallites tilted by 21° is found. The transition from the thin-film phase to the bulk phase is rationalized by the nucleation of the latter at crystal facets of the thin-film-phase crystallites. This leads to a self-limiting growth of the thin-film phase and explains the thickness-dependent phase behavior observed in pentacene thin films, showing that a large amount of material is present in the bulk phase much earlier during the film growth than previously thought.

  5. Theoretical investigation of the thermodynamic properties of metallic thin films

    International Nuclear Information System (INIS)

    Hung, Vu Van; Phuong, Duong Dai; Hoa, Nguyen Thi; Hieu, Ho Khac

    2015-01-01

    The thermodynamic properties of metallic thin films with face-centered cubic structure at ambient conditions were investigated using the statistical moment method including the anharmonicity effects of thermal lattice vibrations. The analytical expressions of Helmholtz free energy, lattice parameter, linear thermal expansion coefficient, specific heats at the constant volume and constant pressure were derived in terms of the power moments of the atomic displacements. Numerical calculations of thermodynamic properties have been performed for Au and Al thin films and compared with those of bulk metals. This research proposes that thermodynamic quantities of thin films approach the values of bulk when the thickness of thin film is about 70 nm. - Highlights: • Thermodynamic properties of thin films were investigated using the moment method. • Expressions of Helmholtz energy, expansion coefficient, specific heats were derived. • Calculations for Au, Al thin films were performed and compared with those of bulks

  6. Theoretical investigation of the thermodynamic properties of metallic thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hung, Vu Van [Vietnam Education Publishing House, 81 Tran Hung Dao, Hanoi (Viet Nam); Phuong, Duong Dai [Hanoi National University of Education, 136 Xuan Thuy, Hanoi (Viet Nam); Hoa, Nguyen Thi [University of Transport and Communications, Lang Thuong, Dong Da, Hanoi (Viet Nam); Hieu, Ho Khac, E-mail: hieuhk@duytan.edu.vn [Institute of Research and Development, Duy Tan University, K7/25 Quang Trung, Danang (Viet Nam)

    2015-05-29

    The thermodynamic properties of metallic thin films with face-centered cubic structure at ambient conditions were investigated using the statistical moment method including the anharmonicity effects of thermal lattice vibrations. The analytical expressions of Helmholtz free energy, lattice parameter, linear thermal expansion coefficient, specific heats at the constant volume and constant pressure were derived in terms of the power moments of the atomic displacements. Numerical calculations of thermodynamic properties have been performed for Au and Al thin films and compared with those of bulk metals. This research proposes that thermodynamic quantities of thin films approach the values of bulk when the thickness of thin film is about 70 nm. - Highlights: • Thermodynamic properties of thin films were investigated using the moment method. • Expressions of Helmholtz energy, expansion coefficient, specific heats were derived. • Calculations for Au, Al thin films were performed and compared with those of bulks.

  7. PZT Thin Film Piezoelectric Traveling Wave Motor

    Science.gov (United States)

    Shen, Dexin; Zhang, Baoan; Yang, Genqing; Jiao, Jiwei; Lu, Jianguo; Wang, Weiyuan

    1995-01-01

    With the development of micro-electro-mechanical systems (MEMS), its various applications are attracting more and more attention. Among MEMS, micro motors, electrostatic and electromagnetic, are the typical and important ones. As an alternative approach, the piezoelectric traveling wave micro motor, based on thin film material and integrated circuit technologies, circumvents many of the drawbacks of the above mentioned two types of motors and displays distinct advantages. In this paper we report on a lead-zirconate-titanate (PZT) piezoelectric thin film traveling wave motor. The PZT film with a thickness of 150 micrometers and a diameter of 8 mm was first deposited onto a metal substrate as the stator material. Then, eight sections were patterned to form the stator electrodes. The rotor had an 8 kHz frequency power supply. The rotation speed of the motor is 100 rpm. The relationship of the friction between the stator and the rotor and the structure of the rotor on rotation were also studied.

  8. Solution processed pentacene thin films and their structural properties

    International Nuclear Information System (INIS)

    Tao Chunlan; Zhang Xuhui; Zhang Fujia; Liu Yiyang; Zhang Haoli

    2007-01-01

    The paper reported the solution process of pentacene thin films from organic solvent O-dichlorobenzene. The pentacene thin films obtained from different conditions were characterized by X-ray diffraction (XRD), optical microscopy, scanning electron microscopy (SEM), and UV-vis spectroscopy. The result shows that the pentacene solution was successfully obtained at a minimum temperature of 40 deg. C. The optimum temperature of forming pentacene thin films was 100 deg. C

  9. Polarized Neutron Reflectivity Simulation of Ferromagnet/ Antiferromagnet Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ki Yeon; Lee, Jeong Soo

    2008-02-15

    This report investigates the current simulating and fitting programs capable of calculating the polarized neutron reflectivity of the exchange-biased ferromagnet/antiferromagnet magnetic thin films. The adequate programs are selected depending on whether nonspin flip and spin flip reflectivities of magnetic thin films and good user interface are available or not. The exchange-biased systems such as Fe/Cr, Co/CoO, CoFe/IrMn/Py thin films have been simulated successfully with selected programs.

  10. A note on structural and dielectric properties of BiFeO3- PbTiO3 and BiFeO3- PbZrO3 composites

    International Nuclear Information System (INIS)

    Satpathy, S. K.; Mohanty, N. K.; Behera, A. K.; Behera, B.; Nayak, P.

    2015-01-01

    The composites of BiFeO 3 -PbTiO 3 (BF-PT) and BiFeO 3 -PbZrO 3 (BF-PZ) were prepared by mixed oxide method. Room temperature X-ray diffraction data confirms the rhombohedral and tetragonal crystal structure respectively. Dielectric constant of BF-PZ is found to give high value compared to BF-PT and hence, there is an increase value of ac conductivity for the former. Both the composites show negative temperature coefficient of resistance (NTCR) behavior. The activation energies of BF-PT and BF-PZ are found to be 0.35 eV and 0.53 eV respectively. The d 33 coefficients are found to be 2.0 and 2.1 pC/N for BF-PT and BF-PZ respectively

  11. Tin oxide transparent thin-film transistors

    International Nuclear Information System (INIS)

    Presley, R E; Munsee, C L; Park, C-H; Hong, D; Wager, J F; Keszler, D A

    2004-01-01

    A SnO 2 transparent thin-film transistor (TTFT) is demonstrated. The SnO 2 channel layer is deposited by RF magnetron sputtering and then rapid thermal annealed in O 2 at 600 deg. C. The TTFT is highly transparent, and enhancement-mode behaviour is achieved by employing a very thin channel layer (10-20 nm). Maximum field-effect mobilities of 0.8 cm 2 V -1 s -1 and 2.0 cm 2 V -1 s -1 are obtained for enhancement- and depletion-mode devices, respectively. The transparent nature and the large drain current on-to-off ratio of 10 5 associated with the enhancement-mode behaviour of these devices may prove useful for novel gas-sensor applications

  12. Deposition and characterisation of epitaxial oxide thin films for SOFCs

    KAUST Repository

    Santiso, José ; Burriel, Mó nica

    2010-01-01

    This paper reviews the recent advances in the use of thin films, mostly epitaxial, for fundamental studies of materials for solid oxide fuel cell (SOFC) applications. These studies include the influence of film microstructure, crystal orientation

  13. Switching, storage, and erasure effects in a superconducting thin film

    International Nuclear Information System (INIS)

    Testardi, L.R.

    1976-01-01

    Thin niobium films can be switched from a superconducting to a resistive state permanently by application of a short electrical pulse. Application of a short pulse of opposite polarity returns the film to the superconducting state

  14. CO2 gas sensitivity of sputtered zinc oxide thin films

    Indian Academy of Sciences (India)

    TECS

    Gas sensitivity; ZnO; sputtering; XRD patterns; structure; thin films. 1. Introduction. Because zinc ... voltage and absorption properties of those fabricated films have been ... tations are useful in many physical applications. The in- plane (Hegde ...

  15. Physics of thin films advances in research and development

    CERN Document Server

    Hass, Georg; Vossen, John L

    2013-01-01

    Physics of Thin Films: Advances in Research and Development, Volume 12 reviews advances that have been made in research and development concerning the physics of thin films. This volume covers a wide range of preparative approaches, physics phenomena, and applications related to thin films. This book is comprised of four chapters and begins with a discussion on metal coatings and protective layers for front surface mirrors used at various angles of incidence from the ultraviolet to the far infrared. Thin-film materials and deposition conditions suitable for minimizing reflectance changes with

  16. Sputtering materials for VLSI and thin film devices

    CERN Document Server

    Sarkar, Jaydeep

    2010-01-01

    An important resource for students, engineers and researchers working in the area of thin film deposition using physical vapor deposition (e.g. sputtering) for semiconductor, liquid crystal displays, high density recording media and photovoltaic device (e.g. thin film solar cell) manufacturing. This book also reviews microelectronics industry topics such as history of inventions and technology trends, recent developments in sputtering technologies, manufacturing steps that require sputtering of thin films, the properties of thin films and the role of sputtering target performance on overall p

  17. Thin-Film Materials Synthesis and Processing Facility

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Provides a wide capability for deposition and processing of thin films, including sputter and ion-beam deposition, thermal evaporation, electro-deposition,...

  18. 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.

  19. Atomic Structure Control of Silica Thin Films on Pt(111)

    KAUST Repository

    Crampton, Andrew S

    2015-05-27

    Metal oxide thin films grown on metal single crystals are commonly used to model heterogeneous catalyst supports. The structure and properties of thin silicon dioxide films grown on metal single crystals have only recently been thoroughly characterized and their spectral properties well established. We report the successful growth of a three- dimensional, vitreous silicon dioxide thin film on the Pt(111) surface and reproduce the closed bilayer structure previously reported. The confirmation of the three dimensional nature of the film is unequivocally shown by the infrared absorption band at 1252 cm−1. Temperature programmed desorption was used to show that this three-dimensional thin film covers the Pt(111) surface to such an extent that its application as a catalyst support for clusters/nanoparticles is possible. The growth of a three-dimensional film was seen to be directly correlated with the amount of oxygen present on the surface after the silicon evaporation process. This excess of oxygen is tentatively attributed to atomic oxygen being generated in the evaporator. The identification of atomic oxygen as a necessary building block for the formation of a three-dimensional thin film opens up new possibilities for thin film growth on metal supports, whereby simply changing the type of oxygen enables thin films with different atomic structures to be synthesized. This is a novel approach to tune the synthesis parameters of thin films to grow a specific structure and expands the options for modeling common amorphous silica supports under ultra high vacuum conditions.

  20. Tension Tests of Copper Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Park, Kyung Jo; Kim, Chung Youb [Chonnam Nat’l Univ., Gwangju (Korea, Republic of)

    2017-08-15

    Tension tests for copper thin films with thickness of 12 μm were performed by using a digital image correlation method based on consecutive digital images. When calculating deformation using digital image correlation, a large deformation causes errors in the calculated result. In this study, the calculation procedure was improved to reduce the error, so that the full field deformation and the strain of the specimen could be accurately and directly measured on its surface. From the calculated result, it can be seen that the strain distribution is not uniform and its variation is severe, unlike the distribution in a common bulk specimen. This might result from the surface roughness introduced in the films during the fabrication process by electro-deposition.

  1. Seebeck effect of some thin film carbides

    International Nuclear Information System (INIS)

    Beensh-Marchwicka, G.; Prociow, E.

    2002-01-01

    Several materials have been investigated for high-temperature thin film thermocouple applications. These include silicon carbide with boron (Si-C-B), ternary composition based on Si-C-Mn, fourfold composition based on Si-C-Zr-B and tantalum carbide (TaC). All materials were deposited on quartz or glass substrates using the pulse sputter deposition technique. Electrical conduction and thermoelectric power were measured for various compositions at 300-550 K. It has been found, that the efficiency of thermoelectric power of films containing Si-C base composition was varied from 0.0015-0.034 μW/cmK 2 . However for TaC the value about 0.093 μW/cmK 2 was obtained. (author)

  2. TEM characterization of nanodiamond thin films.

    Energy Technology Data Exchange (ETDEWEB)

    Qin, L.-C.; Zhou, D.; Krauss, A. R.; Gruen, D. M.; Chemistry

    1998-05-01

    The microstructure of thin films grown by microwave plasma-enhanced chemical vapor deposition (MPCVD) from fullerene C{sub 60} precursors has been characterized by scanning electron microscopy (SEM), selected-area electron diffraction (SAED), bright-field electron microscopy, high-resolution electron microscopy (HREM), and parallel electron energy loss spectroscopy (PEELS). The films are composed of nanosize crystallites of diamond, and no graphitic or amorphous phases were observed. The diamond crystallite size measured from lattice images shows that most grains range between 3-5 nm, reflecting a gamma distribution. SAED gave no evidence of either sp2-bonded glassy carbon or sp3-bonded diamondlike amorphous carbon. The sp2-bonded configuration found in PEELS was attributed to grain boundary carbon atoms, which constitute 5-10% of the total. Occasionally observed larger diamond grains tend to be highly faulted.

  3. Studies of tantalum nitride thin film resistors

    International Nuclear Information System (INIS)

    Langley, R.A.

    1975-01-01

    Backscattering of 2-MeV He ions was used to correlate the electrical properties of sputtered TaN/sub x/ thin-film resistors with their N content. The properties measured were sheet resistance, differential Seebeck potential (DSP), thermal coefficient of resistance (TCR), and stability. Resistivity and DSP are linearly dependent on N content for N/Ta ratios of 0.25 to 0.55. TCR decreases sharply below N/Ta = 0.35 and is relatively constant from 0.35 to 0.55. Stability is independent of N content. (DLC)

  4. Methods for producing thin film charge selective transport layers

    Science.gov (United States)

    Hammond, Scott Ryan; Olson, Dana C.; van Hest, Marinus Franciscus Antonius Maria

    2018-01-02

    Methods for producing thin film charge selective transport layers are provided. In one embodiment, a method for forming a thin film charge selective transport layer comprises: providing a precursor solution comprising a metal containing reactive precursor material dissolved into a complexing solvent; depositing the precursor solution onto a surface of a substrate to form a film; and forming a charge selective transport layer on the substrate by annealing the film.

  5. Chemical vapour deposition of thin-film dielectrics

    International Nuclear Information System (INIS)

    Vasilev, Vladislav Yu; Repinsky, Sergei M

    2005-01-01

    Data on the chemical vapour deposition of thin-film dielectrics based on silicon nitride, silicon oxynitride and silicon dioxide and on phosphorus- and boron-containing silicate glasses are generalised. The equipment and layer deposition procedures are described. Attention is focussed on the analysis and discussion of the deposition kinetics and on the kinetic models for film growth. The film growth processes are characterised and data on the key physicochemical properties of thin-film covalent dielectric materials are given.

  6. Characterization of ultrasonic spray pyrolysed ruthenium oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Patil, P.S.; Ennaoui, E.A.; Lokhande, C.D.; Mueller, M.; Giersig, M.; Diesner, K.; Tributsch, H. [Hahn-Meitner-Institut Berlin GmbH (Germany). Bereich Physikalische Chemie

    1997-11-21

    The ultrasonic spray pyrolysis (USP) technique was employed to deposit ruthenium oxide thin films. The films were prepared at 190 C substrate temperature and further annealed at 350 C for 30 min in air. The films were 0.22 {mu} thick and black grey in color. The structural, compositional and optical properties of ruthenium oxide thin films are reported. Contactless transient photoconductivity measurement was carried out to calculate the decay time of excess charge carriers in ruthenium oxide thin films. (orig.) 28 refs.

  7. Nitrogen incorporation in sputter deposited molybdenum nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Stöber, Laura, E-mail: laura.stoeber@tuwien.ac.at; Patocka, Florian, E-mail: florian.patocka@tuwien.ac.at; Schneider, Michael, E-mail: michael.schneider@tuwien.ac.at; Schmid, Ulrich, E-mail: ulrich.e366.schmid@tuwien.ac.at [Institute of Sensor and Actuator Systems, TU Wien, Gußhausstraße 27-29, A-1040 Vienna (Austria); Konrath, Jens Peter, E-mail: jenspeter.konrath@infineon.com; Haberl, Verena, E-mail: verena.haberl@infineon.com [Infineon Technologies Austria AG, Siemensstraße 2, 9500 Villach (Austria)

    2016-03-15

    In this paper, the authors report on the high temperature performance of sputter deposited molybdenum (Mo) and molybdenum nitride (Mo{sub 2}N) thin films. Various argon and nitrogen gas compositions are applied for thin film synthetization, and the amount of nitrogen incorporation is determined by Auger measurements. Furthermore, effusion measurements identifying the binding conditions of the nitrogen in the thin film are performed up to 1000 °C. These results are in excellent agreement with film stress and scanning electron microscope analyses, both indicating stable film properties up to annealing temperatures of 500 °C.

  8. Dimensional scaling of perovskite ferroelectric thin films

    Science.gov (United States)

    Keech, Ryan R.

    Dimensional size reduction has been the cornerstone of the exponential improvement in silicon based logic devices for decades. However, fundamental limits in the device physics were reached ˜2003, halting further reductions in clock speed without significant penalties in power consumption. This has motivated the research into next generation transistors and switching devices to reinstate the scaling laws for clock speed. This dissertation aims to support the scaling of devices that are based on ferroelectricity and piezoelectricity and to provide a roadmap for the corresponding materials performance. First, a scalable growth process to obtain highly {001}-oriented lead magnesium niobate - lead titanate (PMN-PT) thin films was developed, motivated by the high piezoelectric responses observed in bulk single crystals. It was found that deposition of a 2-3 nm thick PbO buffer layer on {111} Pt thin film bottom electrodes, prior to chemical solution deposition of PMN-PT reduces the driving force for Pb diffusion from the PMN-PT to the bottom electrode, and facilitates nucleation of {001}-oriented perovskite grains. Energy dispersive spectroscopy demonstrated that up to 10% of the Pb from a PMN-PT precursor solution may diffuse into the bottom electrode. PMN-PT grains with a mixed {101}/{111} orientation in a matrix of Pb-deficient pyrochlore phase were then promoted near the interface. When this is prevented, phase pure films with {001} orientation with Lotgering factors of 0.98-1.0, can be achieved. The resulting films of only 300 nm in thickness exhibit longitudinal effective d33,f coefficients of ˜90 pm/V and strain values of ˜1% prior to breakdown. 300 nm thick epitaxial and polycrystalline lead magnesium niobate - lead titanate (70PMN-30PT) blanket thin films were studied for the relative contributions to property thickness dependence from interfacial and grain boundary low permittivity layers. Epitaxial PMN-PT films were grown on SrRuO 3 /(001)SrTiO3, while

  9. Síntese e caracterização de perovesquites do sistema BiFeO3

    OpenAIRE

    Carvalho, Teresa Maria Tranchete de

    2007-01-01

    Dissertação de Mestrado em Física e Química para o Ensino, apresentada à Universidade de Trás-os-Montes e Alto Douro Os materiais multiferróicos, como o caso do BiFeO3, são bastante promissores em termos tecnológicos, possuindo uma potencial aplicação em sensores, memórias não voláteis e actuadores. A perovesquite BiFeO3 apresenta vantagens relativamente a outros compostos multiferróicos: elevada temperatura de Curie (TC=1100 K); elevada temperatura de Néel (TN=640 K); não contém chumbo...

  10. Investigation of electromagnetic properties of BiFeO3 by Time Differential Perturbed Angular Correlation (TDPAC) technique at ISOLDE

    CERN Document Server

    Efe, Ipek

    2017-01-01

    Time differential perturbed angular correlation (TDPAC) technique is one of the most sensitive techniques to study about the electric and magnetic fields at the individual lattice points. It benefits from the hyperfine interactions between the probe atom and its neighborhood. Multiferroic materials have been intensively studied to promote and understand the possibility of controlling magnetic properties by electric fields instead of magnetic fields which opens the path to faster, smaller, and more energy-efficient spintronic devices, such as memory elements, high-frequency magnetic devices, and micro-electro-mechanical systems, for data-storage technologies. BiFeO3 is one of the famous and important multiferroic materials since it shows both antiferromagnetic and ferroelectric behavior at room temperature. In this study, we report on the first time-differential perturbed angular correlation (TDPAC) measurements carried out on polycrystalline BiFeO3 samples using the nuclear probe 181Hf(181Ta) after implantati...

  11. Recent progress of obliquely deposited thin films for industrial applications

    Science.gov (United States)

    Suzuki, Motofumi; Itoh, Tadayoshi; Taga, Yasunori

    1999-06-01

    More than 10 years ago, birefringent films of metal oxides were formed by oblique vapor deposition and investigated with a view of their application to optical retardation plates. The retardation function of the films was explained in terms of the birefringence caused by the characteristic anisotropic nanostructure inside the films. These films are now classified in the genre of the so-called sculptured thin films. However, the birefringent films thus prepared are not yet industrialized even now due to the crucial lack of the durability and the yield of products. In this review paper, we describe the present status of application process of the retardation films to the information systems such as compact disc and digital versatile disc devices with a special emphasis on the uniformity of retardation properties in a large area and the stability of the optical properties of the obliquely deposited thin films. Finally, further challenges for wide application of the obliquely deposited thin films are also discussed.

  12. Operating method of amorphous thin film semiconductor element

    Energy Technology Data Exchange (ETDEWEB)

    Mori, Koshiro; Ono, Masaharu; Hanabusa, Akira; Osawa, Michio; Arita, Takashi

    1988-05-31

    The existing technologies concerning amorphous thin film semiconductor elements are the technologies concerning the formation of either a thin film transistor or an amorphous Si solar cell on a substrate. In order to drive a thin film transistor for electronic equipment control by the output power of an amorphous Si solar cell, it has been obliged to drive the transistor weth an amorphous solar cell which was formed on a substrate different from that for the transistor. Accordingly, the space for the amorphous solar cell, which was formed on the different substrate, was additionally needed on the substrate for the thin film transistor. In order to solve the above problem, this invention proposes an operating method of an amorphous thin film semiconductor element that after forming an amorphous Si solar cell through lamination on the insulation coating film which covers the thin film transistor formed on the substrate, the thin film transistor is driven by the output power of this solar cell. The invention eliminates the above superfluous space and reduces the size of the amorphous thin film semiconductor element including the electric source. (3 figs)

  13. Stable organic thin-film transistors

    Science.gov (United States)

    Jia, Xiaojia; Fuentes-Hernandez, Canek; Wang, Cheng-Yin; Park, Youngrak; Kippelen, Bernard

    2018-01-01

    Organic thin-film transistors (OTFTs) can be fabricated at moderate temperatures and through cost-effective solution-based processes on a wide range of low-cost flexible and deformable substrates. Although the charge mobility of state-of-the-art OTFTs is superior to that of amorphous silicon and approaches that of amorphous oxide thin-film transistors (TFTs), their operational stability generally remains inferior and a point of concern for their commercial deployment. We report on an exhaustive characterization of OTFTs with an ultrathin bilayer gate dielectric comprising the amorphous fluoropolymer CYTOP and an Al2O3:HfO2 nanolaminate. Threshold voltage shifts measured at room temperature over time periods up to 5.9 × 105 s do not vary monotonically and remain below 0.2 V in microcrystalline OTFTs (μc-OTFTs) with field-effect carrier mobility values up to 1.6 cm2 V−1 s−1. Modeling of these shifts as a function of time with a double stretched-exponential (DSE) function suggests that two compensating aging mechanisms are at play and responsible for this high stability. The measured threshold voltage shifts at temperatures up to 75°C represent at least a one-order-of-magnitude improvement in the operational stability over previous reports, bringing OTFT technologies to a performance level comparable to that reported in the scientific literature for other commercial TFTs technologies. PMID:29340301

  14. Properties of superconducting thin-film microbridges

    International Nuclear Information System (INIS)

    Pei, S.S.

    1978-01-01

    This work reports investigations upon the dependences of critical current and current phase relation on the dimensions of a superconducting thin-film microbridge. A model has been developed upon the Volkov's hyperbolic bridges and the Zaitsev's boundary conditions to calculate the spatial variation of the order parameter for given bridge dimensions. The results indicate that the rigid boundary conditions are good approximations to narrow bridges (W much less than L) only. The critical current density of the bridge has been calculated also as a function of the bridge dimensions. It is found that the critical current density of small bridges is enhanced above its mean field critical value due to the proximity effects of the banks. Very good agreement is found between the calculated enhancement of the critical current density and the experimental results. Direct measurements have been made on the current phase relation of indium bridges with width smaller than 0.6 μm. The difficulties due to the extra phase shifts from the series thin film electrodes are overcome by a specially designed double loop configuration which has an extra low effective inductance. It is found that the current phase relation of small bridges (W,L, xi, the results agree with the predictions of rigid boundary calculations as expected by our model

  15. Effects of magnetic annealing on structure and multiferroic properties of pure and dysprosium substituted BiFeO 3

    KAUST Repository

    Zhang, Shuxia; Yao, Yingbang; Chen, Yao; Wang, Dongliang; Zhang, Xianping; Awaji, Satoshi; Watanabe, Kazuo; Ma, Yanwei

    2012-01-01

    In this work, the effects of magnetic annealing on crystal structure and multiferroic properties of BiFeO 3 and Bi 0.85Dy 0.15FeO 3 have been investigated. It is found that the X-ray diffraction patterns of pure BiFeO 3 samples are obviously broadened after magnetic annealing, whereas those of Bi 0.85Dy 0.15FeO 3 samples are almost unchanged. Magnetic field annealing did not affect the magnetic properties of these two kinds of samples much. However, ferroelectric properties of the two materials exhibited different behaviors after magnetic field annealing. For pure BiFeO 3 samples, the remnant polarizations (P r) are suppressed; in contrast, for Bi 0.85Dy 0.15FeO 3 samples, P r is greatly enhanced. Possible mechanisms for the effects of magnetic field annealing have been discussed. © 2012 Elsevier B.V. All rights reserved.

  16. Accuracy and Transferability of Ab Initio Electronic Band Structure Calculations for Doped BiFeO3

    Science.gov (United States)

    Gebhardt, Julian; Rappe, Andrew M.

    2017-11-01

    BiFeO3 is a multiferroic material and, therefore, highly interesting with respect to future oxide electronics. In order to realize such devices, pn junctions need to be fabricated, which are currently impeded by the lack of successful p-type doping in this material. In order to guide the numerous research efforts in this field, we recently finished a comprehensive computational study, investigating the influence of many dopants onto the electronic structure of BiFeO3. In order to allow for this large scale ab initio study, the computational setup had to be accurate and efficient. Here we discuss the details of this assessment, showing that standard density-functional theory (DFT) yields good structural properties. The obtained electronic structure, however, suffers from well-known shortcomings. By comparing the conventional DFT results for alkali and alkaline-earth metal doping with more accurate hybrid-DFT calculations, we show that, in this case, the problems of standard DFT go beyond a simple systematic error. Conventional DFT shows bad transferability and the more reliable hybrid-DFT has to be chosen for a qualitatively correct prediction of doping induced changes in the electronic structure of BiFeO3.

  17. Effects of magnetic annealing on structure and multiferroic properties of pure and dysprosium substituted BiFeO 3

    KAUST Repository

    Zhang, Shuxia

    2012-07-01

    In this work, the effects of magnetic annealing on crystal structure and multiferroic properties of BiFeO 3 and Bi 0.85Dy 0.15FeO 3 have been investigated. It is found that the X-ray diffraction patterns of pure BiFeO 3 samples are obviously broadened after magnetic annealing, whereas those of Bi 0.85Dy 0.15FeO 3 samples are almost unchanged. Magnetic field annealing did not affect the magnetic properties of these two kinds of samples much. However, ferroelectric properties of the two materials exhibited different behaviors after magnetic field annealing. For pure BiFeO 3 samples, the remnant polarizations (P r) are suppressed; in contrast, for Bi 0.85Dy 0.15FeO 3 samples, P r is greatly enhanced. Possible mechanisms for the effects of magnetic field annealing have been discussed. © 2012 Elsevier B.V. All rights reserved.

  18. Influence of the collector and heat treatment in the structure of BiFeO_3 electrospun nanofibers

    International Nuclear Information System (INIS)

    Melo, G.H.F.; Santos, J.P.F.; Bretas, R.E.S.

    2016-01-01

    The objective of this work was to analyze the influence of the collector type and heat treatment on the morphology and crystalline phases of BiFeO_3 electrospun nanofibers. A solution containing (Fe(NO_3)_3_._9H_2O and Bi(NO_3)_3_._5H_2O) as precursors together with a polyvinylpyrrolidone solution was electrospun using 2.8KV/cm as electrical field. The collector type was however, changed (aluminum and glass). After the electrospinning, the as-spun nanofibers were submitted to two different heat treatments: one at 550°C and the other at 750°C, both during 2h. The collector type changed the morphology of the nanofibers; while in the glass collector, a non-woven mat of flat and rough nanofibers was obtained, in the aluminum collector, mats of circular and smooth nanofibers were obtained. The thermal treatment also changed the morphology and amount of crystalline phases; at 550°C, the nanofiber morphology was maintained and only one crystalline phase (BiFeO_3) was detected. On the other hand, at 750°C, flakes were obtained of two crystalline phases (BiFeO_3 and Bi_2Fe_4O_9). (author)

  19. Optical characteristics of the thin-film scintillator detector

    International Nuclear Information System (INIS)

    Muga, L.; Burnsed, D.

    1976-01-01

    A study of the thin-film detector (TFD) was made in which various light guide and scintillator film support configurations were tested for efficiency of light coupling. Masking of selected portions of the photomultiplier (PM) tube face revealed the extent to which emitted light was received at the exposed PM surfaces. By blocking off selected areas of the scintillator film surface from direct view of the PM tube faces, a measure of the light-guiding efficiency of the film and its support could be estimated. The picture that emerges is that, as the light which is initially trapped in the thin film spreads radially outward from the ion entrance/exit point, it is scattered out of the film by minute imperfections. Optimum signals were obtained by a configuration in which the thin scintillator film was supported on a thin rectangular Celluloid frame inserted within a highly polished metal cylindrical sleeve

  20. Band-gap tuning and magnetic properties of heterovalent ions (Ba, Sr and Ca) substituted BiFeO_3 nanoparticles

    International Nuclear Information System (INIS)

    Chauhan, Sunil; Kumar, Manoj; Katyal, S. C.

    2016-01-01

    A Comparative study of heterovalent Ba, Sr and Ca ions substitution on the structural, vibrational, optical and magnetic properties of BiFeO_3 nanoparticles was carried out. The distorted rhombohedral structure was confirmed from both X-ray diffraction and Raman spectroscopy techniques in pure BiFeO_3 and Bi_0_._8_5A_0_._1_5FeO_3 (A= Ba, Sr and Ca) samples. UV-Visible spectroscopy results show that the band-gap of BiFeO_3 nanoparticles can be tuned by heterovalent ions substitution from 2.12 eV for BiFeO_3 to 2.10, 2.06 and 2.03 eV for Ca, Sr and Ba substituted BiFeO_3 nanoparticles respectively. The magnetic measurements indicate enhancement in magnetization for heterovalent A"2"+ substituted BiFeO_3 samples and the magnetization increases with increase of ionic radius of the substituted ions.

  1. Polycystalline silicon thin films for electronic applications

    Energy Technology Data Exchange (ETDEWEB)

    Jaeger, Christian Claus

    2012-01-15

    For the thin polycrystalline Si films fabricated with the aluminium-induced-layer-exchange (ALILE) process a good structural quality up to a layer-thickness value of 10 nm was determined. For 5 nm thick layers however after the layer exchange no closes poly-silicon film was present. In this case the substrate was covered with spherically arranged semiconductor material. Furthermore amorphous contributions in the layer could be determined. The electrical characterization of the samples at room temperature proved a high hole concentration in the range 10{sup 18} cm{sup -3} up to 9.10{sup 19} cm{sup -3}, which is influenced by the process temperature and the layer thickness. Hereby higher hole concentrations at higher process temperatures and thinner films were observed. Furthermore above 150-200 K a thermically activated behaviour of the electrical conductivity was observed. At lower temperatures a deviation of the measured characteristic from the exponential Arrhenius behaviour was determined. For low temperatures (below 20 K) the conductivity follows the behaviour {sigma}{proportional_to}[-(T{sub 0}/T){sup 1/4}]. The hole mobility in the layers was lowered by a passivation step, which can be explained by defect states at the grain boundaries. The for these very thin layers present situation was simulated in the framework of the model of Seto, whereby both the defect states at the grain boundaries (with an area density Q{sub t}) and the defect states at the interfaces (with an area density Q{sub it}) were regarded. By this the values Q{sub t}{approx}(3-4).10{sup 12} cm{sup -2} and Q{sub it}{approx}(2-5).10{sup 12} cm{sup -2} could be determined for these thin ALILE layers on quartz substrates. Additionally th R-ALILE process was studied, which uses the reverse precursor-layer sequence substrate/amorphous silicon/oxide/aluminium. Hereby two steps in the crystallization process of the R-ALILE process were found. First a substrate/Al-Si mixture/poly-Si layer structure

  2. Ferroelectric domain switching dynamics and memristive behaviors in BiFeO3-based magnetoelectric heterojunctions

    Science.gov (United States)

    Huang, Weichuan; Liu, Yukuai; Luo, Zhen; Hou, Chuangming; Zhao, Wenbo; Yin, Yuewei; Li, Xiaoguang

    2018-06-01

    The ferroelectric domain reversal dynamics and the corresponding resistance switching as well as the memristive behaviors in epitaxial BiFeO3 (BFO, ~150 nm) based multiferroic heterojunctions were systematically investigated. The ferroelectric domain reversal dynamics could be described by the nucleation-limited-switching model with the Lorentzian distribution of logarithmic domain-switching times. By engineering the domain states, multi and even continuously tunable resistances states, i.e. memristive states, could be non-volatilely achieved. The resistance switching speed can be as fast as 30 ns in the BFO-based multiferroic heterojunctions with a write voltage of ~20 V. By reducing the thickness of BFO, the La0.6Sr0.4MnO3/BFO (~5 nm)/La0.6Sr0.4MnO3 multiferroic tunnel junction (MFTJ) shows an even a quicker switching speed (20 ns) with a much lower operation voltage (~4 V). Importantly, the MFTJ exhibits a tunable interfacial magnetoelectric coupling related to the ferroelectric domain switching dynamics. These findings enrich the potential applications of multiferroic BFO based devices in high-speed, low-power, and high-density memories as well as future neuromorphic computational architectures.

  3. Influence of cobalt doping on structural and magnetic properties of BiFeO3 nanoparticles

    Science.gov (United States)

    Khan, U.; Adeela, N.; Javed, K.; Riaz, S.; Ali, H.; Iqbal, M.; Han, X. F.; Naseem, S.

    2015-11-01

    Nanocrystalline cobalt-doped bismuth ferrites with general formula of BiFe1- δ Co δ O3 (0 ≤ δ ≤ 0.1) have been synthesized using solution evaporation method. Structure and phase identification was performed with X-ray diffraction (XRD) technique. The results confirm the formation of rhombohedral-distorted Perovskite structure with R3c symmetry. A decrease in lattice parameters and an increase in X-ray density have been observed with increasing cobalt concentration in BiFeO3. Particle size determined by transmission electron microscope was in good agreement with XRD, i.e., 39 nm. Room-temperature coercivity and saturation magnetization of nanoparticles were increased up to 7.5 % of cobalt doping. Low-temperature magnetic measurements of selected sample showed increasing behavior in saturation magnetization, coercivity, effective magnetic moments, and anisotropy constant. An increase in coercivity with decrease in temperature followed theoretical model of Kneller's law, while modified Bloch's model was employed for saturation magnetization in temperature range of 5-300 K.

  4. Presence of glassy state and large exchange bias in nanocrystalline BiFeO3

    Science.gov (United States)

    Srivastav, Simant Kumar; Johari, Anima; Patel, S. K. S.; Gajbhiye, N. S.

    2017-11-01

    We investigated the static and dynamic aspects of the magnetic properties for single phase nanocrystalline BiFeO3 with average crystallite size of 35 nm. The frequency dependence of the peak is observed in the real part of ac susceptibility χ‧ac vs T measurement and described well by the Vogel-Fulcher law as well as the power law. These analyses indicated the existence of cluster glass state with significant interaction among the spin clusters and results in cluster-glass like cooperative freezing at low temperature. The influence of temperature and magnetic field cooling on the exchange bias effect is investigated. A training effect is also observed. We have reported a significantly high ZFC & FC exchange bias of 200 Oe & 450 Oe at 300 K and 900 Oe & 2100 Oe at 5 K. The obtained results are interpreted in the framework of core-shell model, where the core of the BFO nanoparticles shows antiferromagnetic behavior and surrounded by CG-like ferromagnetic (FM) shell associated to uncompensated surface spins.

  5. Magnetic ordering induced giant optical property change in tetragonal BiFeO3

    Science.gov (United States)

    Tong, Wen-Yi; Ding, Hang-Chen; Gong, Shi Jing; Wan, Xiangang; Duan, Chun-Gang

    2015-12-01

    Magnetic ordering could have significant influence on band structures, spin-dependent transport, and other important properties of materials. Its measurement, especially for the case of antiferromagnetic (AFM) ordering, however, is generally difficult to be achieved. Here we demonstrate the feasibility of magnetic ordering detection using a noncontact and nondestructive optical method. Taking the tetragonal BiFeO3 (BFO) as an example and combining density functional theory calculations with tight-binding models, we find that when BFO changes from C1-type to G-type AFM phase, the top of valance band shifts from the Z point to Γ point, which makes the original direct band gap become indirect. This can be explained by Slater-Koster parameters using the Harrison approach. The impact of magnetic ordering on band dispersion dramatically changes the optical properties. For the linear ones, the energy shift of the optical band gap could be as large as 0.4 eV. As for the nonlinear ones, the change is even larger. The second-harmonic generation coefficient d33 of G-AFM becomes more than 13 times smaller than that of C1-AFM case. Finally, we propose a practical way to distinguish the two AFM phases of BFO using the optical method, which is of great importance in next-generation information storage technologies.

  6. Calcination temperature influenced multiferroic properties of Ca-doped BiFeO3 nanoparticles

    International Nuclear Information System (INIS)

    Dhir, Gitanjali; Uniyal, Poonam; Verma, N. K.

    2015-01-01

    The influence of Ca-doping and particle size on structural, morphological and magnetic properties of BiFeO 3 nanoparticles has been studied. A sol-gel method was employed for the synthesis of nanoparticles and their particle size was tailored by varying the calcination temperature. Structural analysis revealed a rhombohedral distortion induced by Ca-substitution. The broadening of diffraction peaks with decreasing calcination temperature was indicative of reduction in crystallite size. The morphological analysis revealed the formation of agglomerated nanoparticles having average particle size ranging from 10-15 and 50-55 nm for C4 and C6, respectively. The agglomeration is attributed to high surface energy of nanoparticles. Ferromagnetism has been displayed by all the synthesized nanoparticles. Enhancement of saturation magnetization with Ca-substitution is attributed to suppression of spin cycloid structure by the reduction in size, lattice distortion and creation of oxygen vacancies by the substitution of divalent ion at trivalent site. Further, this value increases as a function of decreasing particle size. Strong particle size effects on magnetic properties of the synthesized nanoparticles are owed to increasing surface to volume ratio. All these observations are indicative of strong dependence of multiferroism on particle size

  7. Photo catalytic BiFeO3 Nano fibrous Mats for Effective Water Treatment

    International Nuclear Information System (INIS)

    Shaibani, P.M.; Prashanthi, K.; Sohrabi, A.; Thundat, Th.

    2013-01-01

    One-dimensional BiFeO 3 (BFO) nano fibers fabricated by electro spinning of a solution of Nylon 6 /BFO followed by calcination were used for photo catalytic degradation of contaminants in water. The BFO fibers were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and UV-Vis spectroscopy. The SEM images of the as-spun samples demonstrated the successful production of nano fibers and the SEM images of the samples after calcination confirmed the integrity of the continuous BFO nano fibers. XRD analysis indicated the dominant presence of BFO phase throughout the calcinated nano fibers. Photo catalytic activity of the nano fibers and their application in water purification were investigated against 4-chloro phenol (4CP) as a model water contaminant. The results of the UV-Vis spectroscopy show the degradation of the 4CP by means of the photo catalytic activity of the BFO nano fibers. The kinetics of the photodegradation of 4CP is believed to be governed by a pseudo-first-order kinetics model.

  8. Spatially Resolved Large Magnetization in Ultrathin BiFeO3

    KAUST Repository

    Guo, Er-Jia

    2017-06-19

    Here, a quantitative magnetic depth profile across the planar interfaces in BiFeO3 /La0.7 Sr0.3 MnO3 (BFO/LSMO) superlattices using polarized neutron reflectometry is obtained. An enhanced magnetization of 1.83 ± 0.16 μB /Fe in BFO layers is observed when they are interleaved between two manganite layers. The enhanced magnetic order in BFO persists up to 200 K. The depth dependence of magnetic moments in BFO/LSMO superlattices as a function of the BFO layer thickness is also explored. The results show the enhanced net magnetic moment in BFO from the LSMO/BFO interface extends 3-4 unit cells into BFO. The interior part of a thicker BFO layer has a much smaller magnetization, suggesting it still keeps the small canted AFM state. The results exclude charge transfer, intermixing, epitaxial strain, and octahedral rotations/tilts as dominating mechanisms for the large net magnetization in BFO. An explanation-one suggested by others previously and consistent with the observations-attributes the temperature dependence of the net magnetization of BFO to strong orbital hybridization between Fe and Mn across the interfaces. Such orbital reconstruction would establish an upper temperature limit for magnetic ordering of BFO.

  9. Pyroelectric properties and electrical conductivity in samarium doped BiFeO 3 ceramics

    KAUST Repository

    Yao, Yingbang

    2012-06-01

    Samarium (Sm 3+) doped BiFeO 3 (BFO) ceramics were prepared by a modified solid-state-reaction method which adopted a rapid heating as well as cooling during the sintering process. The pyroelectric coefficient increased from 93 to 137 μC/m 2 K as the Sm 3+ doping level increased from 1 mol% to 8 mol%. Temperature dependence of the pyroelectric coefficient showed an abrupt decrease above 80 °C in all samples, which was associated with the increase of electrical conductivity with temperature. This electrical conduction was attributed to oxygen vacancy existing in the samples. An activation energy of ∼0.7 eV for the conduction process was found to be irrespective of the Sm 3+ doping level. On the other hand, the magnetic Néel temperature (T N) decreased with increasing Sm 3+ doping level. On the basis of our results, the effects of Sm doping level on the pyroelectric and electrical properties of the BFO were revealed. © 2011 Elsevier Ltd. All rights reserved.

  10. Functional Properties at Domain Walls in BiFeO3: Electrical, Magnetic, and Structural investigations

    Science.gov (United States)

    He, Qing; Yang, C.-H.; Yu, P.; Gajek, M.; Seidel, J.; Ramesh, R.; Wang, F.; Chu, Y.-H.; Martin, L. W.; Spaldin, N.; Rother, A.

    2009-03-01

    BiFeO3 (BFO) is a widely studied robust ferroelectric, antiferromagnetic multiferroic. Conducting-atomic force microscopy studies reveal the presence of enhanced conductivity at certain types of domain walls in BFO. We have completed detailed TEM studies of the physical structure at these domain walls as well as in-depth DFT calculations of the evolution of electronic structure at these domain walls. These studies reveal two major contributions to the observed conduction: the formation of an electrostatic potential at the domain walls as well as a structurally-driven change in the electronic structure (i.e., a lower band gap locally) at the domain walls. We will discuss the use of optical characterization techniques as a way of probing this change in electronic structure at domain walls as well as detailed IV characterization both in atmospheric and UHV environments. Finally, the evolution of magnetism at these domain walls has been studied through the use of photoemission measurements. Initial findings point to a significant change in the magnetic order at these domain walls in BFO.

  11. Optical constants and structural properties of thin gold films

    DEFF Research Database (Denmark)

    Yakubovsky, Dmitry I.; Arsenin, Aleksey V.; Stebunov, Yury V.

    2017-01-01

    We report a comprehensive experimental study of optical and electrical properties of thin polycrystalline gold films in a wide range of film thicknesses (from 20 to 200 nm). Our experimental results are supported by theoretical calculations based on the measured morphology of the fabricated gold...... rules for thin-film plasmonic and nanophotonic devices....... films. We demonstrate that the dielectric function of the metal is determined by its structural morphology. Although the fabrication process can be absolutely the same for different films, the dielectric function can strongly depend on the film thickness. Our studies show that the imaginary part...

  12. Thinning and rupture of a thin liquid film on a heated surface

    Energy Technology Data Exchange (ETDEWEB)

    Bankoff, S.G.; Davis, S.H.

    1992-08-05

    Results on the dynamics and stability of thin films are summarized on the following topics: forced dryout, film instabilities on a horizontal plane and on inclined planes, instrumentation, coating flows, and droplet spreading. (DLC)

  13. Microbridge tests on gallium nitride thin films

    International Nuclear Information System (INIS)

    Huang, Hai-You; Li, Zhi-Ying; Lu, Jun-Yong; Wang, Zhi-Jia; Zhang, Tong-Yi; Wang, Chong-Shun; Lau, Kei-May; Chen, Kevin Jing

    2009-01-01

    In this work, we develop further the microbridge testing method by deriving a closed formula of deflection versus load, which is applied at an arbitrary position on the microbridge beam. Testing a single beam at various positions allows us to characterize simultaneouslyYoung's modulus and residual stress of the beam. The developed method was then used to characterize the mechanical properties of GaN thin films on patterned-Si (1 1 1) substrates grown by metal organic chemical vapor deposition (MOCVD). The microbridge samples were fabricated by using the microelectromechanical fabrication technique and tested with a nanoindentation system. Young's modulus and residual stress of the GaN films were determined to be 287 ± 190 GPa and 851 ± 155 MPa, respectively. In addition, alternative measurements of the residual stress, Young's modulus and hardness of the GaN films, were conducted with micro-Raman spectroscopy and the nanoindentation test, yielding the corresponding values of 847 ± 46 MPa, 269.0 ± 7.0 GPa and 17.8 ± 1.1 GPa

  14. Surface microtopography of thin silver films

    Science.gov (United States)

    Costa, Manuel F. M.; Almeida, Jose B.

    1991-01-01

    The authors present ne applications for the recently developed nori-contact optical inicrotopographer emphasizing the results of topographic inspections of thin silver films edges. These films were produced by sputtering of silver through different masks, using a planar magnetron source. The results show the influence ot the thickness and position of the masks on the topography of the film near its edge. Topographic information is obtained from the horizontal shift incurred by the bright spot on an horizontal surface, which is displaced vertically, when this is illuminated by an oblique collimated laser beam. The laser beam is focused onto the surface into a diffraction limited spot and is made to sweep the surface to be examined.. The horizontal position of the bright spot is continuously imaged onto a light detector array and the information about individual detectors that are activated is used to compute the corresponding horizontal shift on the reference plane. Simple trignometric calculations are used to relate the horizontal shift to the distance between the surface and a reference plane at each sampling point and thus a map of the surface topography can be built.

  15. Controlled nanostructuration of polycrystalline tungsten thin films

    Energy Technology Data Exchange (ETDEWEB)

    Girault, B. [Institut P' (UPR 3346 CNRS), Universite de Poitiers, ENSMA, Bd Pierre et Marie Curie, 86962 Futuroscope Cedex (France); Institut de Recherche en Genie Civil et Mecanique (UMR CNRS 6183), LUNAM Universite, Universite de Nantes, Centrale Nantes, CRTT, 37 Bd de l' Universite, BP 406, 44602 Saint-Nazaire Cedex (France); Eyidi, D.; Goudeau, P.; Guerin, P.; Bourhis, E. Le; Renault, P.-O. [Institut P' (UPR 3346 CNRS), Universite de Poitiers, ENSMA, Bd Pierre et Marie Curie, 86962 Futuroscope Cedex (France); Sauvage, T. [CEMHTI/CNRS (UPR 3079 CNRS), Universite d' Orleans, 3A rue de la Ferollerie, 45071 Orleans Cedex 2 (France)

    2013-05-07

    Nanostructured tungsten thin films have been obtained by ion beam sputtering technique stopping periodically the growing. The total thickness was maintained constant while nanostructure control was obtained using different stopping periods in order to induce film stratification. The effect of tungsten sublayers' thicknesses on film composition, residual stresses, and crystalline texture evolution has been established. Our study reveals that tungsten crystallizes in both stable {alpha}- and metastable {beta}-phases and that volume proportions evolve with deposited sublayers' thicknesses. {alpha}-W phase shows original fiber texture development with two major preferential crystallographic orientations, namely, {alpha}-W<110> and unexpectedly {alpha}-W<111> texture components. The partial pressure of oxygen and presence of carbon have been identified as critical parameters for the growth of metastable {beta}-W phase. Moreover, the texture development of {alpha}-W phase with two texture components is shown to be the result of a competition between crystallographic planes energy minimization and crystallographic orientation channeling effect maximization. Controlled grain size can be achieved for the {alpha}-W phase structure over 3 nm stratification step. Below, the {beta}-W phase structure becomes predominant.

  16. Surfactant induced flows in thin liquid films : an experimental study

    NARCIS (Netherlands)

    Sinz, D.K.N.

    2012-01-01

    The topic of the experimental work summarized in my thesis is the flow in thin liquid films induced by non-uniformly distributed surfactants. The flow dynamics as a consequence of the deposition of a droplet of an insoluble surfactant onto a thin liquid film covering a solid substrate where

  17. Optimized grid design for thin film solar panels

    NARCIS (Netherlands)

    Deelen, J. van; Klerk, L.; Barink, M.

    2014-01-01

    There is a gap in efficiency between record thin film cells and mass produced thin film solar panels. In this paper we quantify the effect of monolithic integration on power output for various configurations by modeling and present metallization as a way to improve efficiency of solar panels. Grid

  18. Dynamics of a spreading thin film with gravitational counterflow ...

    Indian Academy of Sciences (India)

    film climbing up on a vertical substrate against gravity shows interesting dynamics ... For the spreading of a thin film several theoretical studies have shown quantitative agree- ..... The two critical values of this param- ... Davis J M, Fischer B J and Troian S M 2003 A general approach to the linear stability of thin spreading.

  19. Plastic response of thin films due to thermal cycling

    NARCIS (Netherlands)

    Nicola, L.; van der Giessen, E.; Needleman, A.; Ahzi, S; Cherkaoui, M; Khaleel, MA; Zbib, HM; Zikry, MA; Lamatina, B

    2004-01-01

    Discrete dislocation simulations of thin films on semi-infinite substrates under cyclic thermal loading are presented. The thin film is modelled as a two-dimensional single crystal under plane strain conditions. Dislocations of edge character can be generated from initially present sources and glide

  20. Cadmium sulphide thin film for application in gamma radiation ...

    African Journals Online (AJOL)

    Cadmium Sulphide (CdS) thin film was prepared using pyrolytic spraying technique and then irradiated at varied gamma dosage. The CdS thin film absorption before gamma irradiation was 0.6497. Absorbed doses were computed using standard equation established for an integrating dosimeter. The plot of absorbed dose ...

  1. Electrical properties of epitaxially grown VOx thin films

    NARCIS (Netherlands)

    Rata, A.D.; Chezan, A.R; Presura, C.N.; Hibma, T

    2003-01-01

    High quality VOx thin films on MgO(100) substrates were prepared and studied from the structural and electronic point of view. Epitaxial growth was confirmed by RHEED and XRD techniques. The oxygen content of VOx thin films as a function of oxygen flux was determined using RBS. The upper and lower

  2. Determination of oxygen diffusion kinetics during thin film ruthenium oxidation

    NARCIS (Netherlands)

    Coloma Ribera, R.; van de Kruijs, Robbert Wilhelmus Elisabeth; Yakshin, Andrey; Bijkerk, Frederik

    2015-01-01

    In situ X-ray reflectivity was used to reveal oxygen diffusion kinetics for thermal oxidation of polycrystalline ruthenium thin films and accurate determination of activation energies for this process. Diffusion rates in nanometer thin RuO2 films were found to show Arrhenius behaviour. However, a

  3. Thin films of metal-organic compounds and metal nanoparticle

    Indian Academy of Sciences (India)

    Thin films of metal-organic compounds and metal nanoparticle-embedded polymers for nonlinear optical applications. S Philip Anthony Shatabdi Porel D ... Thin films based on two very different metal-organic systems are developed and some nonlinear optical applications are explored. A family of zinc complexes which ...

  4. Fabrication and Performance Study of Uniform Thin Film Integrated ...

    African Journals Online (AJOL)

    The transmission line model of a uniform rectangular thin film R-C-KR structure consisting of a dielectric layer of constant per unit shunt capacitance C sandwiched between two resistive thin films of constant per unit length resistances R and KR has been analysed using the concept of matrix parameter functions. The above ...

  5. Thermal stability of gold-PS nanocomposites thin films

    Indian Academy of Sciences (India)

    Low-temperature transmission electron microscopy (TEM) studies were performed on polystyrene (PS, w = 234 K) – Au nanoparticle composite thin films that were annealed up to 350°C under reduced pressure conditions. The composite thin films were prepared by wet chemical approach and the samples were then ...

  6. Thermal properties and stabilities of polymer thin films

    International Nuclear Information System (INIS)

    Kanaya, Toshiji; Kawashima, Kazuko; Inoue, Rintaro; Miyazaki, Tsukasa

    2009-01-01

    Recent extensive studies have revealed that polymer thin films showed very interesting but unusual thermal properties and stabilities. In the article we show that X-ray reflectivity and neutron reflectivity are very powerful tools to study the anomalous properties of polymer thin films. (author)

  7. Piezoelectric MEMS: Ferroelectric thin films for MEMS applications

    Science.gov (United States)

    Kanno, Isaku

    2018-04-01

    In recent years, piezoelectric microelectromechanical systems (MEMS) have attracted attention as next-generation functional microdevices. Typical applications of piezoelectric MEMS are micropumps for inkjet heads or micro-gyrosensors, which are composed of piezoelectric Pb(Zr,Ti)O3 (PZT) thin films and have already been commercialized. In addition, piezoelectric vibration energy harvesters (PVEHs), which are regarded as one of the key devices for Internet of Things (IoT)-related technologies, are promising future applications of piezoelectric MEMS. Significant features of piezoelectric MEMS are their simple structure and high energy conversion efficiency between mechanical and electrical domains even on the microscale. The device performance strongly depends on the function of the piezoelectric thin films, especially on their transverse piezoelectric properties, indicating that the deposition of high-quality piezoelectric thin films is a crucial technology for piezoelectric MEMS. On the other hand, although the difficulty in measuring the precise piezoelectric coefficients of thin films is a serious obstacle in the research and development of piezoelectric thin films, a simple unimorph cantilever measurement method has been proposed to obtain precise values of the direct or converse transverse piezoelectric coefficient of thin films, and recently this method has become to be the standardized testing method. In this article, I will introduce fundamental technologies of piezoelectric thin films and related microdevices, especially focusing on the deposition of PZT thin films and evaluation methods for their transverse piezoelectric properties.

  8. Density functional study of ferromagnetism in alkali metal thin films

    Indian Academy of Sciences (India)

    thickness uniform jellium model (UJM), and it is argued that within LSDA or GGA, alkali metal thin films cannot be claimed to have an FM ground state. Relevance of these results to the experiments on transition metal-doped alkali metal thin films ...

  9. NbN thin films for superconducting radio frequency cavities

    Science.gov (United States)

    Roach, W. M.; Skuza, J. R.; Beringer, D. B.; Li, Z.; Clavero, C.; Lukaszew, R. A.

    2012-12-01

    NbN thin films have the potential to be incorporated into radio frequency cavities in a multilayer coating to overcome the fundamental field gradient limit of 50 MV m-1 for the bulk niobium based technology that is currently implemented in particle accelerators. In addition to having a larger critical field value than bulk niobium, NbN films develop smoother surfaces which are optimal for cavity performance and lead to fewer losses. Here, we present a study on the correlation of film deposition parameters, surface morphology, microstructure, transport properties and superconducting properties of NbN thin films. We have achieved films with bulk-like lattice parameters and superconducting transition temperatures. These NbN films have a lower surface roughness than similarly grown niobium films of comparable thickness. The potential application of NbN thin films in accelerator cavities is discussed.

  10. NbN thin films for superconducting radio frequency cavities

    International Nuclear Information System (INIS)

    Roach, W M; Clavero, C; Lukaszew, R A; Skuza, J R; Beringer, D B; Li, Z

    2012-01-01

    NbN thin films have the potential to be incorporated into radio frequency cavities in a multilayer coating to overcome the fundamental field gradient limit of 50 MV m −1 for the bulk niobium based technology that is currently implemented in particle accelerators. In addition to having a larger critical field value than bulk niobium, NbN films develop smoother surfaces which are optimal for cavity performance and lead to fewer losses. Here, we present a study on the correlation of film deposition parameters, surface morphology, microstructure, transport properties and superconducting properties of NbN thin films. We have achieved films with bulk-like lattice parameters and superconducting transition temperatures. These NbN films have a lower surface roughness than similarly grown niobium films of comparable thickness. The potential application of NbN thin films in accelerator cavities is discussed. (paper)

  11. Magnetic damping phenomena in ferromagnetic thin-films and multilayers

    Science.gov (United States)

    Azzawi, S.; Hindmarch, A. T.; Atkinson, D.

    2017-11-01

    Damped ferromagnetic precession is an important mechanism underpinning the magnetisation processes in ferromagnetic materials. In thin-film ferromagnets and ferromagnetic/non-magnetic multilayers, the role of precession and damping can be critical for spintronic device functionality and as a consequence there has been significant research activity. This paper presents a review of damping in ferromagnetic thin-films and multilayers and collates the results of many experimental studies to present a coherent synthesis of the field. The terms that are used to define damping are discussed with the aim of providing consistent definitions for damping phenomena. A description of the theoretical basis of damping is presented from early developments to the latest discussions of damping in ferromagnetic thin-films and multilayers. An overview of the time and frequency domain methods used to study precessional magnetisation behaviour and damping in thin-films and multilayers is also presented. Finally, a review of the experimental observations of magnetic damping in ferromagnetic thin-films and multilayers is presented with the most recent explanations. This brings together the results from many studies and includes the effects of ferromagnetic film thickness, the effects of composition on damping in thin-film ferromagnetic alloys, the influence of non-magnetic dopants in ferromagnetic films and the effects of combining thin-film ferromagnets with various non-magnetic layers in multilayered configurations.

  12. Nanocoatings and ultra-thin films technologies and applications

    CERN Document Server

    Tiginyanu, Ion

    2011-01-01

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

  13. Infrared analysis of thin films amorphous, hydrogenated carbon on silicon

    CERN Document Server

    Jacob, W; Schwarz-Selinger, T

    2000-01-01

    The infrared analysis of thin films on a thick substrate is discussed using the example of plasma-deposited, amorphous, hydrogenated carbon layers (a-C:H) on silicon substrates. The framework for the optical analysis of thin films is presented. The main characteristic of thin film optics is the occurrence of interference effects due to the coherent superposition of light multiply reflected at the various internal and external interfaces of the optical system. These interference effects lead to a sinusoidal variation of the transmitted and reflected intensity. As a consequence, the Lambert-Beer law is not applicable for the determination of the absorption coefficient of thin films. Furthermore, observable changes of the transmission and reflection spectra occur in the vicinity of strong absorption bands due to the Kramers-Kronig relation. For a sound data evaluation these effects have to be included in the analysis. To be able to extract the full information contained in a measured optical thin film spectrum, ...

  14. Room temperature ferroelectricity in continuous croconic acid thin films

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Xuanyuan; Lu, Haidong; Yin, Yuewei; Ahmadi, Zahra; Costa, Paulo S. [Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588 (United States); Zhang, Xiaozhe [Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588 (United States); Department of Physics, Xi' an Jiaotong University, Xi' an 710049 (China); Wang, Xiao; Yu, Le; Cheng, Xuemei [Department of Physics, Bryn Mawr College, Bryn Mawr, Pennsylvania 19010 (United States); DiChiara, Anthony D. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Gruverman, Alexei, E-mail: alexei-gruverman@unl.edu, E-mail: a.enders@me.com, E-mail: xiaoshan.xu@unl.edu; Enders, Axel, E-mail: alexei-gruverman@unl.edu, E-mail: a.enders@me.com, E-mail: xiaoshan.xu@unl.edu; Xu, Xiaoshan, E-mail: alexei-gruverman@unl.edu, E-mail: a.enders@me.com, E-mail: xiaoshan.xu@unl.edu [Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588 (United States); Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588 (United States)

    2016-09-05

    Ferroelectricity at room temperature has been demonstrated in nanometer-thin quasi 2D croconic acid thin films, by the polarization hysteresis loop measurements in macroscopic capacitor geometry, along with observation and manipulation of the nanoscale domain structure by piezoresponse force microscopy. The fabrication of continuous thin films of the hydrogen-bonded croconic acid was achieved by the suppression of the thermal decomposition using low evaporation temperatures in high vacuum, combined with growth conditions far from thermal equilibrium. For nominal coverages ≥20 nm, quasi 2D and polycrystalline films, with an average grain size of 50–100 nm and 3.5 nm roughness, can be obtained. Spontaneous ferroelectric domain structures of the thin films have been observed and appear to correlate with the grain patterns. The application of this solvent-free growth protocol may be a key to the development of flexible organic ferroelectric thin films for electronic applications.

  15. Room temperature deposition of magnetite thin films on organic substrate

    International Nuclear Information System (INIS)

    Arisi, E.; Bergenti, I.; Cavallini, M.; Murgia, M.; Riminucci, A.; Ruani, G.; Dediu, V.

    2007-01-01

    We report on the growth of magnetite films directly on thin layers of organic semiconductors by means of an electron beam ablation method. The deposition was performed at room temperature in a reactive plasma atmosphere. Thin films show ferromagnetic (FM) hysteresis loops and coercive fields of hundreds of Oersted. Micro Raman analysis indicates no presence of spurious phases. The morphology of the magnetite film is strongly influenced by the morphology of the underlayer of the organic semiconductor. These results open the way for the application of magnetite thin films in the field of organic spintronics

  16. Thin Films for Advanced Glazing Applications

    Directory of Open Access Journals (Sweden)

    Ann-Louise Anderson

    2016-09-01

    Full Text Available Functional thin films provide many opportunities for advanced glazing systems. This can be achieved by adding additional functionalities such as self-cleaning or power generation, or alternately by providing energy demand reduction through the management or modulation of solar heat gain or blackbody radiation using spectrally selective films or chromogenic materials. Self-cleaning materials have been generating increasing interest for the past two decades. They may be based on hydrophobic or hydrophilic systems and are often inspired by nature, for example hydrophobic systems based on mimicking the lotus leaf. These materials help to maintain the aesthetic properties of the building, help to maintain a comfortable working environment and in the case of photocatalytic materials, may provide external pollutant remediation. Power generation through window coatings is a relatively new idea and is based around the use of semi-transparent solar cells as windows. In this fashion, energy can be generated whilst also absorbing some solar heat. There is also the possibility, in the case of dye sensitized solar cells, to tune the coloration of the window that provides unheralded external aesthetic possibilities. Materials and coatings for energy demand reduction is highly desirable in an increasingly energy intensive world. We discuss new developments with low emissivity coatings as the need to replace scarce indium becomes more apparent. We go on to discuss thermochromic systems based on vanadium dioxide films. Such systems are dynamic in nature and present a more sophisticated and potentially more beneficial approach to reducing energy demand than static systems such as low emissivity and solar control coatings. The ability to be able to tune some of the material parameters in order to optimize the film performance for a given climate provides exciting opportunities for future technologies. In this article, we review recent progress and challenges in

  17. Modifying thin film diamond for electronic applications

    International Nuclear Information System (INIS)

    Baral, B.

    1999-01-01

    The unique combination of properties that diamond possesses are being exploited in both electronic and mechanical applications. An important step forward in the field has been the ability to grow thin film diamond by chemical vapour deposition (CVD) methods and to control parameters such as crystal orientation, dopant level and surface roughness. An extensive understanding of the surface of any potential electronic material is vital to fully comprehend its behaviour within device structures. The surface itself ultimately controls key aspects of device performance when interfaced with other materials. This study has provided insight into important chemical reactions on polycrystalline CVD diamond surfaces, addressing how certain surface modifications will ultimately affect the properties of the material. A review of the structure, bonding, properties and potential of diamond along with an account of the current state of diamond technology and CVD diamond growth is provided. The experimental chapter reviews bulk material and surface analytical techniques employed in this work and is followed by an investigation of cleaning treatments for polycrystalline CVD diamond aimed at removing non-diamond carbon from the surface. Selective acid etch treatments are compared and contrasted for efficacy with excimer laser irradiation and hydrogen plasma etching. The adsorption/desorption kinetics of potential dopant-containing precursors on polycrystalline CVD diamond surfaces have been investigated to compare their effectiveness at introducing dopants into the diamond during the growth stage. Both boron and sulphur-containing precursor compounds have been investigated. Treating polycrystalline CVD diamond in various atmospheres / combination of atmospheres has been performed to enhance electron field emission from the films. Films which do not emit electrons under low field conditions can be modified such that they emit at fields as low as 10 V/μm. The origin of this enhancement

  18. Evaluation of residual stress in sputtered tantalum thin-film

    Energy Technology Data Exchange (ETDEWEB)

    Al-masha’al, Asa’ad, E-mail: asaad.al@ed.ac.uk; Bunting, Andrew; Cheung, Rebecca

    2016-05-15

    Highlights: • Tantalum thin-films have been deposited by DC magnetron sputtering system. • Thin-film stress is observed to be strongly influenced by sputtering pressure. • Transition towards the compressive stress is ascribed to the annealing at 300 °C. • Expose thin-film to air ambient or ion bombardment lead to a noticeable change in the residual stress. - Abstract: The influence of deposition conditions on the residual stress of sputtered tantalum thin-film has been evaluated in the present study. Films have been deposited by DC magnetron sputtering and curvature measurement method has been employed to calculate the residual stress of the films. Transitions of tantalum film stress from compressive to tensile state have been observed as the sputtering pressure increases. Also, the effect of annealing process at temperature range of 90–300 °C in oxygen ambient on the residual stress of the films has been studied. The results demonstrate that the residual stress of the films that have been deposited at lower sputtering pressure has become more compressive when annealed at 300 °C. Furthermore, the impact of exposure to atmospheric ambient on the tantalum film stress has been investigated by monitoring the variation of the residual stress of both annealed and unannealed films over time. The as-deposited films have been exposed to pure Argon energy bombardment and as result, a high compressive stress has been developed in the films.

  19. The Structure and Stability of Molybdenum Ditelluride Thin Films

    Directory of Open Access Journals (Sweden)

    Zhouling Wang

    2014-01-01

    Full Text Available Molybdenum-tellurium alloy thin films were fabricated by electron beam evaporation and the films were annealed in different conditions in N2 ambient. The hexagonal molybdenum ditelluride thin films with well crystallization annealed at 470°C or higher were obtained by solid state reactions. Thermal stability measurements indicate the formation of MoTe2 took place at about 350°C, and a subtle weight-loss was in the range between 30°C and 500°C. The evolution of the chemistry for Mo-Te thin films was performed to investigate the growth of the MoTe2 thin films free of any secondary phase. And the effect of other postdeposition treatments on the film characteristics was also investigated.

  20. Investigation of ferromagnetism in oxygen deficient hafnium oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hildebrandt, Erwin; Kurian, Jose; Krockenberger, Yoshiharu; Alff, Lambert [Institut fuer Materialwissenschaft, TU Darmstadt (Germany); Suter, Andreas [PSI, Villingen (Switzerland); Wilhelm, Fabrice; Rogalev, Andrei [ESRF, Grenoble (France)

    2008-07-01

    Oxygen deficient thin films of hafnium oxide were grown on single crystal r-cut and c-cut sapphire by reactive molecular beam epitaxy. RF-activated oxygen was used for the in situ oxidation of hafnium oxide thin films. Oxidation conditions were varied substantially in order to create oxygen deficiency in hafnium oxide films intentionally. The films were characterized by X-ray and magnetic measurements. X-ray diffraction studies show an increase in lattice parameter with increasing oxygen deficiency. Oxygen deficient hafnium oxide thin films also showed a decreasing bandgap with increase in oxygen deficiency. The magnetisation studies carried out with SQUID did not show any sign of ferromagnetism in the whole oxygen deficiency range. X-ray magnetic circular dichroism measurements also confirmed the absence of ferromagnetism in oxygen deficient hafnium oxide thin films.

  1. In vitro behaviour of nanocrystalline silver-sputtered thin films

    International Nuclear Information System (INIS)

    Piedade, A P; Vieira, M T; Martins, A; Silva, F

    2007-01-01

    Silver thin films were deposited with different preferential orientations and special attention was paid to the bioreactivity of the surfaces. The study was essentially focused on the evaluation of the films by x-ray diffraction (XRD), atomic force microscopy (AFM), high-resolution transmission electron microscopy (HRTEM), electron probe microanalysis (EPMA) and contact angle measurements. The deposited thin films were characterized before and after immersion in S-enriched simulated human plasma in order to estimate the influence of the preferential crystallographic orientation on the in vitro behaviour. Silver thin films with and without (111) preferential crystallographic orientation were deposited by r.f. magnetron sputtering to yield nanocrystalline coatings, high compact structures, very hydrophobic surfaces and low roughness. These properties reduce the chemisorption of reactive species onto the film surface. The in vitro tests indicate that silver thin films can be used as coatings for biomaterials applications

  2. Novel photon management for thin-film photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Menon, Rajesh [Univ. of Utah, Salt Lake City, UT (United States)

    2016-11-11

    The objective of this project is to enable commercially viable thin-film photovoltaics whose efficiencies are increased by over 10% using a novel optical spectral-separation technique. A thin planar diffractive optic is proposed that efficiently separates the solar spectrum and assigns these bands to optimal thin-film sub-cells. An integrated device that is comprised of the optical element, an array of sub-cells and associated packaging is proposed.

  3. Altering properties of cerium oxide thin films by Rh doping

    International Nuclear Information System (INIS)

    Ševčíková, Klára; Nehasil, Václav; Vorokhta, Mykhailo; Haviar, Stanislav; Matolín, Vladimír

    2015-01-01

    Highlights: • Thin films of ceria doped by rhodium deposited by RF magnetron sputtering. • Concentration of rhodium has great impact on properties of Rh–CeO x thin films. • Intensive oxygen migration in films with low concentration of rhodium. • Oxygen migration suppressed in films with high amount of Rh dopants. - Abstract: Ceria containing highly dispersed ions of rhodium is a promising material for catalytic applications. The Rh–CeO x thin films with different concentrations of rhodium were deposited by RF magnetron sputtering and were studied by soft and hard X-ray photoelectron spectroscopies, Temperature programmed reaction and X-ray powder diffraction techniques. The sputtered films consist of rhodium–cerium mixed oxide where cerium exhibits a mixed valency of Ce 4+ and Ce 3+ and rhodium occurs in two oxidation states, Rh 3+ and Rh n+ . We show that the concentration of rhodium has a great influence on the chemical composition, structure and reducibility of the Rh–CeO x thin films. The films with low concentrations of rhodium are polycrystalline, while the films with higher amount of Rh dopants are amorphous. The morphology of the films strongly influences the mobility of oxygen in the material. Therefore, varying the concentration of rhodium in Rh–CeO x thin films leads to preparing materials with different properties

  4. Pulsed laser deposition and characterisation of thin superconducting films

    Energy Technology Data Exchange (ETDEWEB)

    Morone, A [CNR, zona industriale di Tito Scalo, Potenza (Italy). Istituto per i Materiali Speciali

    1996-09-01

    Same concepts on pulsed laser deposition of thin films will be discussed and same examples of high transition temperature (HTc) BiSrCaCuO (BISCO) and low transition temperature NbN/MgO/NbN multilayers will be presented. X-ray and others characterizations of these films will be reported and discussed. Electrical properties of superconducting thin films will be realized as a function of structural and morphological aspect.

  5. Thin film coatings for space electrical power system applications

    Science.gov (United States)

    Gulino, Daniel A.

    1988-01-01

    This paper examines some of the ways in which thin film coatings can play a role in aerospace applications. Space systems discussed include photovoltaic and solar dynamic electric power generation systems, including applications in environmental protection, thermal energy storage, and radiator emittance enhancement. Potential applications of diamondlike films to both atmospheric and space based systems are examined. Also, potential uses of thin films of the recently discovered high-temperature superconductive materials are discussed.

  6. Preparation and optical characterization of DNA-riboflavin thin films

    Science.gov (United States)

    Paulson, Bjorn; Shin, Inchul; Kong, Byungjoo; Sauer, Gregor; Dugasani, Sreekantha Reddy; Khazaeinezhad, Reza; Jung, Woohyun; Joo, Boram; Oh, Kyunghwan

    2016-09-01

    Thin films of DNA biopolymer thin film are fabricated by a drop casting process on glass and silicon substrates, as well as freestanding. The refractive index is measured by elliposmetry and in bulk DNA film the refractive index is shown to be increased in the 600 to 900 nm DNA transparency window by doping with riboflavin. Further analysis with FT-IR, Raman, and XRD are used to determine whether binding between riboflavin and DNA occurs.

  7. Thin film adhesion by nanoindentation-induced superlayers. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Gerberich, William W.; Volinsky, A.A.

    2001-06-01

    This work has analyzed the key variables of indentation tip radius, contact radius, delamination radius, residual stress and superlayer/film/interlayer properties on nanoindentation measurements of adhesion. The goal to connect practical works of adhesion for very thin films to true works of adhesion has been achieved. A review of this work titled ''Interfacial toughness measurements of thin metal films,'' which has been submitted to Acta Materialia, is included.

  8. Simple turbulence measurements with azopolymer thin films.

    Science.gov (United States)

    Barillé, Regis; Pérez, Darío G; Morille, Yohann; Zielińska, Sonia; Ortyl, Ewelina

    2013-04-01

    A simple method to measure the influence on the laser beam propagation by a turbid medium is proposed. This measurement is based on the inscription of a surface relief grating (SRG) on an azopolymer thin film. The grating obtained with a single laser beam after propagation into a turbulent medium is perturbed and directly analyzed by a CCD camera through its diffraction pattern. Later, by scanning the surface pattern with an atomic force microscope, the inscribed SRG is analyzed with the Radon transform. This method has the advantage of using a single beam to remotely inscribe a grating detecting perturbations during the beam path. A method to evaluate the refractive index constant structure is developed.

  9. Thin film femtosecond laser damage competition

    Science.gov (United States)

    Stolz, Christopher J.; Ristau, Detlev; Turowski, Marcus; Blaschke, Holger

    2009-10-01

    In order to determine the current status of thin film laser resistance within the private, academic, and government sectors, a damage competition was started at the 2008 Boulder Damage Symposium. This damage competition allows a direct comparison of the current state of the art of high laser resistance coatings since they are tested using the same damage test setup and the same protocol. In 2009 a high reflector coating was selected at a wavelength of 786 nm at normal incidence at a pulse length of 180 femtoseconds. 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, and spectral results will also be shared.

  10. PZT thin film actuated elastic fin micromotor.

    Science.gov (United States)

    Dubois, M A; Muralt, P

    1998-01-01

    A piezoelectric elastic fin micromotor based on a PbZr(0.53 )Ti(0.47)O(3) thin film driving a micromachined silicon membrane was fabricated and studied. The stator was characterized by interferometry, and a laser set-up was used to measure the angular velocity and acceleration of the motor. The torque, the output power, and the efficiency of the device were extracted from these measurements. Values up to 1020 rpm and 0.94 microNm were observed for the velocity and the torque, respectively, which would be sufficient for a wristwatch application. The present version exhibited an efficiency of 0.17%, which could theoretically be increased to 4.8%

  11. Quantitative MFM on superconducting thin films

    Energy Technology Data Exchange (ETDEWEB)

    Stopfel, Henry; Vock, Silvia; Shapoval, Tetyana; Neu, Volker; Wolff, Ulrike; Haindl, Silvia; Engelmann, Jan; Schaefer, Rudolf; Holzapfel, Bernhard; Schultz, Ludwig [IFW Dresden, Institute for Metallic Material (Germany); Inosov, Dmytro S. [Max Planck Institute for Solid State Research, Stuttgart (Germany)

    2012-07-01

    Quantitative interpretation of magnetic force microscopy (MFM) data is a challenge, because the measured signal is a convolution between the magnetization of the tip and the stray field emanated by the sample. It was established theoretically that the field distribution just above the surface of the superconductor can be well approximated by the stray field of a magnetic monopole. The description of the MFM tip, however, needs a second approximation. The temperature-dependent vortex-distribution images on a NbN thin film were fitted using two different tip models. Firstly, the magnetic tip was assumed to be a monopole that leads to the simple monopole-monopole model for the tip-sample interaction force. Performing a 2D fitting of the data with this model, we extracted λ, Δ and the vortex pinning force. Secondly, a geometrical model was applied to calculate the tip-transfer-function of the MFM tip using the numerical BEM method.

  12. Multiferroics and magnetoelectrics: thin films and nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Martin, L W; Crane, S P; Chu, Y-H; Holcomb, M B; Gajek, M; Huijben, M; Yang, C-H; Balke, N; Ramesh, R [Department of Materials Science and Engineering, University of California, Berkeley, CA 94720 (United States); Department of Physics, University of California, Berkeley, CA 94720 (United States); Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)], E-mail: lwmartin@lbl.gov

    2008-10-29

    Multiferroic materials, or materials that simultaneously possess two or more ferroic order parameters, have returned to the forefront of materials research. Driven by the desire to achieve new functionalities-such as electrical control of ferromagnetism at room temperature-researchers have undertaken a concerted effort to identify and understand the complexities of multiferroic materials. The ability to create high quality thin film multiferroics stands as one of the single most important landmarks in this flurry of research activity. In this review we discuss the basics of multiferroics including the important order parameters and magnetoelectric coupling in materials. We then discuss in detail the growth of single phase, horizontal multilayer, and vertical heterostructure multiferroics. The review ends with a look to the future and how multiferroics can be used to create new functionalities in materials.

  13. Multiferroics and magnetoelectrics: thin films and nanostructures

    Science.gov (United States)

    Martin, L. W.; Crane, S. P.; Chu, Y.-H.; Holcomb, M. B.; Gajek, M.; Huijben, M.; Yang, C.-H.; Balke, N.; Ramesh, R.

    2008-10-01

    Multiferroic materials, or materials that simultaneously possess two or more ferroic order parameters, have returned to the forefront of materials research. Driven by the desire to achieve new functionalities—such as electrical control of ferromagnetism at room temperature—researchers have undertaken a concerted effort to identify and understand the complexities of multiferroic materials. The ability to create high quality thin film multiferroics stands as one of the single most important landmarks in this flurry of research activity. In this review we discuss the basics of multiferroics including the important order parameters and magnetoelectric coupling in materials. We then discuss in detail the growth of single phase, horizontal multilayer, and vertical heterostructure multiferroics. The review ends with a look to the future and how multiferroics can be used to create new functionalities in materials.

  14. Multiferroics and magnetoelectrics: thin films and nanostructures

    International Nuclear Information System (INIS)

    Martin, L W; Crane, S P; Chu, Y-H; Holcomb, M B; Gajek, M; Huijben, M; Yang, C-H; Balke, N; Ramesh, R

    2008-01-01

    Multiferroic materials, or materials that simultaneously possess two or more ferroic order parameters, have returned to the forefront of materials research. Driven by the desire to achieve new functionalities-such as electrical control of ferromagnetism at room temperature-researchers have undertaken a concerted effort to identify and understand the complexities of multiferroic materials. The ability to create high quality thin film multiferroics stands as one of the single most important landmarks in this flurry of research activity. In this review we discuss the basics of multiferroics including the important order parameters and magnetoelectric coupling in materials. We then discuss in detail the growth of single phase, horizontal multilayer, and vertical heterostructure multiferroics. The review ends with a look to the future and how multiferroics can be used to create new functionalities in materials.

  15. Fluctuation conductivity of thin superconductive vanadium films

    International Nuclear Information System (INIS)

    Dmitrenko, I.M.; Sidorenko, A.S.; Fogel, N.Y.

    1982-01-01

    Resistive transitions into the superconductive state are studied in thin [d >T/sub c/ the experimental data on the excess conductivity of the films agree qualitatively and quantitively with Aslamazov--Larkin theory. There is no Maki--Thompson contribution to fluctuation conductivity. Near T/sub c/ the excess conductivity sigma' changes exponentially with temperature in accordance with the predictions of the theory of the critical fluctuations of the order parameter. The values of the effective charge carrier mass defined from data on sigma' for the low fluctuation and critical fluctuation regions differ markedly. This difference is within the spread of effective masses for various charge carrier groups already known for vanadium. Causes of the difference in resistive behavior for the regions T >T/sub c/ are considered

  16. The Characterization of Thin Film Nickel Titanium Shape Memory Alloys

    Science.gov (United States)

    Harris Odum, Nicole Latrice

    Shape memory alloys (SMA) are able to recover their original shape through the appropriate heat or stress exposure after enduring mechanical deformation at a low temperature. Numerous alloy systems have been discovered which produce this unique feature like TiNb, AgCd, NiAl, NiTi, and CuZnAl. Since their discovery, bulk scale SMAs have undergone extensive material property investigations and are employed in real world applications. However, its thin film counterparts have been modestly investigated and applied. Researchers have introduced numerous theoretical microelectromechanical system (MEMS) devices; yet, the research community's overall unfamiliarity with the thin film properties has delayed growth in this area. In addition, it has been difficult to outline efficient thin film processing techniques. In this dissertation, NiTi thin film processing and characterization techniques will be outlined and discussed. NiTi thin films---1 mum thick---were produced using sputter deposition techniques. Substrate bound thin films were deposited to analysis the surface using Scanning Electron Microscopy; the film composition was obtained using Energy Dispersive Spectroscopy; the phases were identified using X-ray diffraction; and the transformation temperatures acquired using resistivity testing. Microfabrication processing and sputter deposition were employed to develop tensile membranes for membrane deflection experimentation to gain insight on the mechanical properties of the thin films. The incorporation of these findings will aid in the movement of SMA microactuation devices from theory to fruition and greatly benefit industries such as medicinal and aeronautical.

  17. Thin Film Approaches to the SRF Cavity Problem Fabrication and Characterization of Superconducting Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Beringer, Douglas [College of William and Mary, Williamsburg, VA (United States)

    2017-08-01

    Superconducting Radio Frequency (SRF) cavities are responsible for the acceleration of charged particles to relativistic velocities in most modern linear accelerators, such as those employed at high-energy research facilities like Thomas Jefferson National Laboratory’s CEBAF and the LHC at CERN. Recognizing SRF as primarily a surface phenomenon enables the possibility of applying thin films to the interior surface of SRF cavities, opening a formidable tool chest of opportunities by combining and designing materials that offer greater performance benefit. Thus, while improvements in radio frequency cavity design and refinements in cavity processing techniques have improved accelerator performance and efficiency – 1.5 GHz bulk niobium SRF cavities have achieved accelerating gradients in excess of 35 MV/m – there exist fundamental material bounds in bulk superconductors limiting the maximally sustained accelerating field gradient (≈ 45 MV/m for Nb) where inevitable thermodynamic breakdown occurs. With state of the art Nb based cavity design fast approaching these theoretical limits, novel material innovations must be sought in order to realize next generation SRF cavities. One proposed method to improve SRF performance is to utilize thin film superconducting-insulating-superconducting (SIS) multilayer structures to effectively magnetically screen a bulk superconducting layer such that it can operate at higher field gradients before suffering critically detrimental SRF losses. This dissertation focuses on the production and characterization of thin film superconductors for such SIS layers for radio frequency applications. Correlated studies on structure, surface morphology and superconducting properties of epitaxial Nb and MgB2 thin films are presented.

  18. Fluorine doped vanadium dioxide thin films for smart windows

    International Nuclear Information System (INIS)

    Kiri, Pragna; Warwick, Michael E.A.; Ridley, Ian; Binions, Russell

    2011-01-01

    Thermochromic fluorine doped thin films of vanadium dioxide were deposited from the aerosol assisted chemical vapour deposition reaction of vanadyl acetylacetonate, ethanol and trifluoroacetic acid on glass substrates. The films were characterised with scanning electron microscopy, variable temperature Raman spectroscopy and variable temperature UV/Vis spectroscopy. The incorporation of fluorine in the films led to an increase in the visible transmittance of the films whilst retaining the thermochromic properties. This approach shows promise for improving the aesthetic properties of vanadium dioxide thin films.

  19. Sensing of volatile organic compounds by copper phthalocyanine thin films

    Science.gov (United States)

    Ridhi, R.; Saini, G. S. S.; Tripathi, S. K.

    2017-02-01

    Thin films of copper phthalocyanine have been deposited by thermal evaporation technique. We have subsequently exposed these films to the vapours of methanol, ethanol and propanol. Optical absorption, infrared spectra and electrical conductivities of these films before and after exposure to chemical vapours have been recorded in order to study their sensing mechanisms towards organic vapours. These films exhibit maximum sensing response to methanol while low sensitivities of the films towards ethanol and propanol have been observed. The changes in sensitivities have been correlated with presence of carbon groups in the chemical vapours. The effect of different types of electrodes on response-recovery times of the thin film with organic vapours has been studied and compared. The electrodes gap distance affects the sensitivity as well as response-recovery time values of the thin films.

  20. Glass transition and thermal expansivity of polystyrene thin films

    International Nuclear Information System (INIS)

    Inoue, R.; Kanaya, T.; Miyazaki, T.; Nishida, K.; Tsukushi, I.; Shibata, K.

    2006-01-01

    We have studied glass transition temperature and thermal expansivity of polystyrene thin films supported on silicon substrate using X-ray reflectivity and inelastic neutron scattering techniques. In annealing experiments, we have found that the reported apparent negative expansivity of polymer thin films is caused by unrelaxed structure due to insufficient annealing. Using well-annealed films, we have evaluated glass transition temperature T g and thermal expansivity as a function of film thickness. The glass transition temperature decreases with film thickness and is constant below about 10 nm, suggesting the surface glass transition temperature of 355 K, which is lower than that in bulk. We have also found that the thermal expansivity in the glassy state decreases with film thickness even after annealing. The decrease has been attributed to hardening of harmonic force constant arising from chain confinement in a thin film. This idea has been confirmed in the inelastic neutron scattering measurements

  1. Glass transition and thermal expansivity of polystyrene thin films

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, R. [Institute for Chemical Research, Kyoto University, Uji, Kyoto-fu 611-0011 (Japan); Kanaya, T. [Institute for Chemical Research, Kyoto University, Uji, Kyoto-fu 611-0011 (Japan)]. E-mail: kanaya@scl.kyoto-u.ac.jp; Miyazaki, T. [Nitto Denko Corporation, 1-1-2 Shimohozumi, Ibaraki, Osaka-fu 567-8680 (Japan); Nishida, K. [Institute for Chemical Research, Kyoto University, Uji, Kyoto-fu 611-0011 (Japan); Tsukushi, I. [Chiba Institute of Technology, Narashino, Chiba-ken 275-0023 (Japan); Shibata, K. [Japan Atomic Energy Research Institute, Tokai, Ibaraki-ken 319-1195 (Japan)

    2006-12-20

    We have studied glass transition temperature and thermal expansivity of polystyrene thin films supported on silicon substrate using X-ray reflectivity and inelastic neutron scattering techniques. In annealing experiments, we have found that the reported apparent negative expansivity of polymer thin films is caused by unrelaxed structure due to insufficient annealing. Using well-annealed films, we have evaluated glass transition temperature T {sub g} and thermal expansivity as a function of film thickness. The glass transition temperature decreases with film thickness and is constant below about 10 nm, suggesting the surface glass transition temperature of 355 K, which is lower than that in bulk. We have also found that the thermal expansivity in the glassy state decreases with film thickness even after annealing. The decrease has been attributed to hardening of harmonic force constant arising from chain confinement in a thin film. This idea has been confirmed in the inelastic neutron scattering measurements.

  2. Thin film characterization by resonantly excited internal standing waves

    Energy Technology Data Exchange (ETDEWEB)

    Di Fonzio, S [SINCROTRONE TRIESTE, Trieste (Italy)

    1996-09-01

    This contribution describes how a standing wave excited in a thin film can be used for the characterization of the properties of the film. By means of grazing incidence X-ray reflectometry one can deduce the total film thickness. On the other hand in making use of a strong resonance effect in the electric field intensity distribution inside a thin film on a bulk substrate one can learn more about the internal structure of the film. The profile of the internal standing wave is proven by diffraction experiments. The most appropriate non-destructive technique for the subsequent thin film characterization is angularly dependent X-ray fluorescence analysis. The existence of the resonance makes it a powerful tool for the detection of impurities and of ultra-thin maker layers, for which the position can be determined with very high precision (about 1% of the total film thickness). This latter aspect will be discussed here on samples which had a thin Ti marker layer at different positions in a carbon film. Due to the resonance enhancement it was still possible to perform these experiments with a standard laboratory x-ray tube and with standard laboratory tool for marker or impurity detection in thin films.

  3. Thin Film Approaches to the SRF Cavity Problem: Fabrication and Characterization of Superconducting Thin Films

    Science.gov (United States)

    Beringer, Douglas B.

    Superconducting Radio Frequency (SRF) cavities are responsible for the acceleration of charged particles to relativistic velocities in most modern linear accelerators, such as those employed at high-energy research facilities like Thomas Jefferson National Laboratory's CEBAF and the LHC at CERN. Recognizing SRF as primarily a surface phenomenon enables the possibility of applying thin films to the interior surface of SRF cavities, opening a formidable tool chest of opportunities by combining and designing materials that offer greater benefit. Thus, while improvements in radio frequency cavity design and refinements in cavity processing techniques have improved accelerator performance and efficiency - 1.5 GHz bulk niobium SRF cavities have achieved accelerating gradients in excess of 35 MV/m - there exist fundamental material bounds in bulk superconductors limiting the maximally sustained accelerating field gradient (approximately 45 MV/m for Niobium) where inevitable thermodynamic breakdown occurs. With state of the art niobium based cavity design fast approaching these theoretical limits, novel material innovations must be sought in order to realize next generation SRF cavities. One proposed method to improve SRF performance is to utilize thin film superconducting-insulating-superconducting (SIS) multilayer structures to effectively magnetically screen a bulk superconducting layer such that it can operate at higher field gradients before suffering critically detrimental SRF losses. This dissertation focuses on the production and characterization of thin film superconductors for such SIS layers for radio-frequency applications.

  4. Thin-film growth and the shadow instability

    International Nuclear Information System (INIS)

    Karunasiri, R.P.U.; Bruinsma, R.; Rudnick, J.

    1989-01-01

    We propose a growth model for deposition of thin amorphous films by the sputtering technique. For small values of the diffusion constant, the film develops a self-similar mountain landscape. As the diffusion constant is increased a regime is reached where growth of compact flat films is possible up to a critical height. Further deposition leads to surface roughening

  5. Inhomogeneous strain states in sputter deposited tungsten thin films

    International Nuclear Information System (INIS)

    Noyan, I.C.; Shaw, T.M.; Goldsmith, C.C.

    1997-01-01

    The results of an x-ray diffraction study of dc-magnetron sputtered tungsten thin films are reported. It is shown that the phase transformation from the β to α W can cause multilayered single-phase films where the layers have very different stress states even if the films are in the 500 nm thickness range. copyright 1997 American Institute of Physics

  6. Strain-induced properties of epitaxial VOx thin films

    NARCIS (Netherlands)

    Rata, AD; Hibma, T

    We have grown VOx thin films on different substrates in order to investigate the influence of epitaxial strain on the transport properties. We found that the electric conductivity is much larger for films grown under compressive strain on SrTiO3 substrates, as compared to bulk material and VOx films

  7. Electrical Conductivity of CUXS Thin Film Deposited by Chemical ...

    African Journals Online (AJOL)

    Thin films of CuxS have successfully been deposited on glass substrates using the Chemical Bath Deposition (CBD) technique. The films were then investigated for their electrical properties. The results showed that the electrical conductivities of the CuxS films with different molarities (n) of thiourea (Tu), determined using ...

  8. Photoinduced conductivity in tin dioxide thin films

    International Nuclear Information System (INIS)

    Muraoka, Y.; Takubo, N.; Hiroi, Z.

    2009-01-01

    The effects of ultraviolet light irradiation on the conducting properties of SnO 2-x thin films grown epitaxially on TiO 2 or Al 2 O 3 single-crystal substrates are studied at room temperature. A large increase in conductivity by two to four orders of magnitude is observed with light irradiation in an inert atmosphere and remains after the light is removed. The high-conducting state reverts to the original low-conducting state by exposing it to oxygen gas. These reversible phenomena are ascribed to the desorption and adsorption of negatively charged oxygen species at the grain boundaries, which critically change the mobility of electron carriers already present inside grains by changing the potential barrier height at the grain boundary. The UV light irradiation provides us with an easy and useful route to achieve a high-conducting state even at low carrier density in transparent conducting oxides and also to draw an invisible conducting wire or a specific pattern on an insulating film.

  9. Electrodeposition of thin Pd-Ag films

    International Nuclear Information System (INIS)

    Hasler, P.; Allmendinger, T.

    1993-01-01

    Thin Pd-Ag layers were electroplated preferably on brass and on nickel substrates using a two-compartment cell separated by an anion exchange membrane. The weakly alkaline electrolyte contained glycine-glycinate as the major complexing agents. The plating experiments were usually carried out without stirring, at different potentials and temperatures and in the absence or in the presence of sodium benzaldehyde-2,4-disulphonate (BDS). The samples were characterized by scanning electron microscopy and light microscopy. Their compositions were determined analytically by the inductively coupled plasma technique. In addition, the film porosity was tested. Electrodeposition in almost limiting current conditions for both components and without simultaneous hydrogen evolution led to deposits with compositions being in good agreement with the molar metal ratio in the electrolyte (77:23). The best results were achieved between 0 and -50 mV with respect to a reversible hydrogen electrode at 0 C in the presence of BDS. These deposits were bright, had good adherence and exhibited no pores at a film thickness of 1.2 μm. At too negative potentials, the deposits became black and powdery. (orig.)

  10. Mechanics of evolving thin film structures

    Science.gov (United States)

    Liang, Jim

    In the Stranski-Krastanov system, the lattice mismatch between the film and the substrate causes the film to break into islands. During annealing, both the surface energy and the elastic energy drive the islands to coarsen. Motivated by several related studies, we suggest that stable islands should form when a stiff ceiling is placed at a small gap above the film. We show that the role of elasticity is reversed: with the ceiling, the total elastic energy stored in the system increases as the islands coarsen laterally. Consequently, the islands select an equilibrium size to minimize the combined elastic energy and surface energy. In lithographically-induced self-assembly, when a two-phase fluid confined between parallel substrates is subjected to an electric field, one phase can self-assemble into a triangular lattice of islands in another phase. We describe a theory of the stability of the island lattice. The islands select the equilibrium diameter to minimize the combined interface energy and electrostatic energy. Furthermore, we study compressed SiGe thin film islands fabricated on a glass layer, which itself lies on a silicon wafer. Upon annealing, the glass flows, and the islands relax. A small island relaxes by in-plane expansion. A large island, however, wrinkles at the center before the in-plane relaxation arrives. The wrinkles may cause significant tensile stress in the island, leading to fracture. We model the island by the von Karman plate theory and the glass layer by the Reynolds lubrication theory. Numerical simulations evolve the in-plane expansion and the wrinkles simultaneously. We determine the critical island size, below which in-plane expansion prevails over wrinkling. Finally, in devices that integrate dissimilar materials in small dimensions, crack extension in one material often accompanies inelastic deformation in another. We analyze a channel crack advancing in an elastic film under tension, while an underlayer creeps. We use a two

  11. Subtractive fabrication of ferroelectric thin films with precisely controlled thickness

    Science.gov (United States)

    Ievlev, Anton V.; Chyasnavichyus, Marius; Leonard, Donovan N.; Agar, Joshua C.; Velarde, Gabriel A.; Martin, Lane W.; Kalinin, Sergei V.; Maksymovych, Petro; Ovchinnikova, Olga S.

    2018-04-01

    The ability to control thin-film growth has led to advances in our understanding of fundamental physics as well as to the emergence of novel technologies. However, common thin-film growth techniques introduce a number of limitations related to the concentration of defects on film interfaces and surfaces that limit the scope of systems that can be produced and studied experimentally. Here, we developed an ion-beam based subtractive fabrication process that enables creation and modification of thin films with pre-defined thicknesses. To accomplish this we transformed a multimodal imaging platform that combines time-of-flight secondary ion mass spectrometry with atomic force microscopy to a unique fabrication tool that allows for precise sputtering of the nanometer-thin layers of material. To demonstrate fabrication of thin-films with in situ feedback and control on film thickness and functionality we systematically studied thickness dependence of ferroelectric switching of lead-zirconate-titanate, within a single epitaxial film. Our results demonstrate that through a subtractive film fabrication process we can control the piezoelectric response as a function of film thickness as well as improve on the overall piezoelectric response versus an untreated film.

  12. Thermoelectric effects of amorphous Ga-Sn-O thin film

    Science.gov (United States)

    Matsuda, Tokiyoshi; Uenuma, Mutsunori; Kimura, Mutsumi

    2017-07-01

    The thermoelectric effects of an amorphous Ga-Sn-O (a-GTO) thin film have been evaluated as a physical parameter of a novel oxide semiconductor. Currently, a-GTO thin films are greatly desired not only because they do not contain rare metals and are therefore free from problems on the exhaustion of resources and the increase in cost but also because their initial characteristics and performance stabilities are excellent when they are used in thin-film transistors. In this study, an a-GTO thin film was deposited on a quartz substrate by RF magnetron sputtering and postannealing was performed in air at 350 °C for 1 h using an annealing furnace. The Seebeck coefficient and electrical conductivity of the a-GTO thin film were -137 µV/K and 31.8 S/cm at room temperature, and -183 µV/K and 43.8 S/cm at 397 K, respectively, and as a result, the power factor was 1.47 µW/(cm·K2) at 397 K; these values were roughly as high as those of amorphous In-Ga-Zn-O (a-IGZO) thin films. Therefore, a-GTO thin films will be a candidate material for thermoelectric devices fabricated in a large area at a low cost by controlling the carrier mobility, carrier density, device structures, and so forth.

  13. Relaxation in Thin Polymer Films Mapped across the Film Thickness by Astigmatic Single-Molecule Imaging

    KAUST Repository

    Oba, Tatsuya; Vacha, Martin

    2012-01-01

    We have studied relaxation processes in thin supported films of poly(methyl acrylate) at the temperature corresponding to 13 K above the glass transition by monitoring the reorientation of single perylenediimide molecules doped into the films

  14. Resistivity of thiol-modified gold thin films

    International Nuclear Information System (INIS)

    Correa-Puerta, Jonathan; Del Campo, Valeria; Henríquez, Ricardo; Häberle, Patricio

    2014-01-01

    In this work, we study the effect of thiol self assembled monolayers on the electrical resistivity of metallic thin films. The analysis is based on the Fuchs–Sondheimer–Lucas theory and on electrical transport measurements. We determined resistivity change due to dodecanethiol adsorption on gold thin films. For this purpose, we controlled the deposition and annealing temperatures of the films to change the surface topography and to diminish the effect of electron grain boundary scattering. Results show that the electrical response to the absorption of thiols strongly depends on the initial topography of the surface. - Highlights: • We study the effect of self assembled monolayers on the resistivity of thin films. • Fuchs–Sondheimer theory reproduces the resistivity increase due to thiol deposition. • We determined resistivity change due to dodecanethiol deposition on gold thin films. • The electrical response strongly depends on the substrate surface topography

  15. Electrochemical Deposition of Lanthanum Telluride Thin Films and Nanowires

    Science.gov (United States)

    Chi, Su (Ike); Farias, Stephen; Cammarata, Robert

    2013-03-01

    Tellurium alloys are characterized by their high performance thermoelectric properties and recent research has shown nanostructured tellurium alloys display even greater performance than bulk equivalents. Increased thermoelectric efficiency of nanostructured materials have led to significant interests in developing thin film and nanowire structures. Here, we report on the first successful electrodeposition of lanthanum telluride thin films and nanowires. The electrodeposition of lanthanum telluride thin films is performed in ionic liquids at room temperature. The synthesis of nanowires involves electrodepositing lanthanum telluride arrays into anodic aluminum oxide (AAO) nanoporous membranes. These novel procedures can serve as an alternative means of simple, inexpensive and laboratory-environment friendly methods to synthesize nanostructured thermoelectric materials. The thermoelectric properties of thin films and nanowires will be presented to compare to current state-of-the-art thermoelectric materials. The morphologies and chemical compositions of the deposited films and nanowires are characterized using SEM and EDAX analysis.

  16. Effect of solution concentration on MEH-PPV thin films

    Science.gov (United States)

    Affendi, I. H. H.; Sarah, M. S. P.; Alrokayan, Salman A. H.; Khan, Haseeb A.; Rusop, M.

    2018-05-01

    MEH-PPV thin films were prepared with a mixture of THF (tetrahydrofuran) solution deposited by spin coating method. The surface topology of MEH-PPV thin film were characterize by atomic force microscopy (AFM) and optical properties of absorption spectra were characterized by using Ultraviolet-visible-near-infrared (UV-Vis-NIR). The MEH-PPV concentration variation affects the surface and optical properties of the thin film where 0.5 mg/ml MEH-PPV concentration have a good surface topology provided the same film also gives the highest absorption coefficient were then deposited to a TiO2 thin film forming composite layer. The composite layer then shows low current flow of short circuit current of Isc = -5.313E-7 A.

  17. Resistivity of thiol-modified gold thin films

    Energy Technology Data Exchange (ETDEWEB)

    Correa-Puerta, Jonathan [Instituto de Física, Pontificia Universidad Católica de Valparaíso, Av. Universidad 330, Curauma, Valparaíso (Chile); Del Campo, Valeria [Departamento de Física, Universidad Técnica Federico Santa María, Av. España 1680, Valparaiso 2390123 (Chile); Henríquez, Ricardo, E-mail: ricardo.henriquez@usm.cl [Departamento de Física, Universidad Técnica Federico Santa María, Av. España 1680, Valparaiso 2390123 (Chile); Häberle, Patricio [Departamento de Física, Universidad Técnica Federico Santa María, Av. España 1680, Valparaiso 2390123 (Chile)

    2014-11-03

    In this work, we study the effect of thiol self assembled monolayers on the electrical resistivity of metallic thin films. The analysis is based on the Fuchs–Sondheimer–Lucas theory and on electrical transport measurements. We determined resistivity change due to dodecanethiol adsorption on gold thin films. For this purpose, we controlled the deposition and annealing temperatures of the films to change the surface topography and to diminish the effect of electron grain boundary scattering. Results show that the electrical response to the absorption of thiols strongly depends on the initial topography of the surface. - Highlights: • We study the effect of self assembled monolayers on the resistivity of thin films. • Fuchs–Sondheimer theory reproduces the resistivity increase due to thiol deposition. • We determined resistivity change due to dodecanethiol deposition on gold thin films. • The electrical response strongly depends on the substrate surface topography.

  18. Valence control of cobalt oxide thin films by annealing atmosphere

    International Nuclear Information System (INIS)

    Wang Shijing; Zhang Boping; Zhao Cuihua; Li Songjie; Zhang Meixia; Yan Liping

    2011-01-01

    The cobalt oxide (CoO and Co 3 O 4 ) thin films were successfully prepared using a spin-coating technique by a chemical solution method with CH 3 OCH 2 CH 2 OH and Co(NO 3 ) 2 .6H 2 O as starting materials. The grayish cobalt oxide films had uniform crystalline grains with less than 50 nm in diameter. The phase structure is able to tailor by controlling the annealing atmosphere and temperature, in which Co 3 O 4 thin film was obtained by annealing in air at 300-600, and N 2 at 300, and transferred to CoO thin film by raising annealing temperature in N 2 . The fitted X-ray photoelectron spectroscopy (XPS) spectra of the Co2p electrons are distinguishable from different valence states of cobalt oxide especially for their satellite structure. The valence control of cobalt oxide thin films by annealing atmosphere contributes to the tailored optical absorption property.

  19. Laser nanostructuring of ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Nedyalkov, N., E-mail: nned@ie.bas.bg [Department of Electronics and Electrical Engineering, Keio University, 3-14-1 Hiyoshi Kohoku-ku, Yokohama-shi, Kanagawa-ken 223-8522 (Japan); Institute of Electronics, Bulgarian Academy of Sciences, Tzarigradsko shousse 72, Sofia 1784 (Bulgaria); Koleva, M.; Nikov, R.; Atanasov, P. [Institute of Electronics, Bulgarian Academy of Sciences, Tzarigradsko shousse 72, Sofia 1784 (Bulgaria); Nakajima, Y.; Takami, A.; Shibata, A.; Terakawa, M. [Department of Electronics and Electrical Engineering, Keio University, 3-14-1 Hiyoshi Kohoku-ku, Yokohama-shi, Kanagawa-ken 223-8522 (Japan)

    2016-06-30

    Highlights: • Nanosecond laser pulse nanostructuring of ZnO thin films on metal substrate is demonstrated. • Two regimes of the thin film modification are observed depending on the applied laser fluence. • At high fluence regime the ZnO film is homogeneously decomposed into nanosized particles. • The characteristic size of the formed nanostructures corresponds to the domain size of the thin film. - Abstract: In this work, results on laser processing of thin zinc oxide films deposited on metal substrate are presented. ZnO films are obtained by classical nanosecond pulsed laser deposition method in oxygen atmosphere on tantalum substrate. The produced films are then processed by nanosecond laser pulses at wavelength of 355 nm. The laser processing parameters and the film thickness are varied and their influence on the fabricated structures is estimated. The film morphology after the laser treatment is found to depend strongly on the laser fluence as two regimes are defined. It is shown that at certain conditions (high fluence regime) the laser treatment of the film leads to formation of a discrete nanostructure, composed of spherical like nanoparticles with narrow size distribution. The dynamics of the melt film on the substrate and fast cooling are found to be the main mechanisms for fabrication of the observed structures. The demonstrated method is an alternative way for direct fabrication of ZnO nanostructures on metal which can be easy implemented in applications as resistive sensor devices, electroluminescent elements, solar cell technology.

  20. Oxidation of ruthenium thin films using atomic oxygen

    Energy Technology Data Exchange (ETDEWEB)

    McCoy, A.P.; Bogan, J.; Brady, A.; Hughes, G.

    2015-12-31

    In this study, the use of atomic oxygen to oxidise ruthenium thin films is assessed. Atomic layer deposited (ALD) ruthenium thin films (~ 3 nm) were exposed to varying amounts of atomic oxygen and the results were compared to the impact of exposures to molecular oxygen. X-ray photoelectron spectroscopy studies reveal substantial oxidation of metallic ruthenium films to RuO{sub 2} at exposures as low as ~ 10{sup 2} L at 575 K when atomic oxygen was used. Higher exposures of molecular oxygen resulted in no metal oxidation highlighting the benefits of using atomic oxygen to form RuO{sub 2}. Additionally, the partial oxidation of these ruthenium films occurred at temperatures as low as 293 K (room temperature) in an atomic oxygen environment. - Highlights: • X-ray photoelectron spectroscopy study of the oxidation of Ru thin films • Oxidation of Ru thin films using atomic oxygen • Comparison between atomic oxygen and molecular oxygen treatments on Ru thin films • Fully oxidised RuO{sub 2} thin films formed with low exposures to atomic oxygen.

  1. Molecular simulation of freestanding amorphous nickel thin films

    Energy Technology Data Exchange (ETDEWEB)

    Dong, T.Q. [Université Paris-Est, Laboratoire Modélisation et Simulation Multi Echelle, UMR 8208 CNRS, 5 Boulevard Descartes, 77454 Marne-la-Vallée, Cedex 2 (France); Hoang, V.V., E-mail: vvhoang2002@yahoo.com [Department of Physics, Institute of Technology, National University of Ho Chi Minh City, 268 Ly Thuong Kiet Street, District 10, Ho Chi Minh City (Viet Nam); Lauriat, G. [Université Paris-Est, Laboratoire Modélisation et Simulation Multi Echelle, UMR 8208 CNRS, 5 Boulevard Descartes, 77454 Marne-la-Vallée, Cedex 2 (France)

    2013-10-31

    Size effects on glass formation in freestanding Ni thin films have been studied via molecular dynamics simulation with the n-body Gupta interatomic potential. Atomic mechanism of glass formation in the films is determined via analysis of the spatio-temporal arrangements of solid-like atoms occurred upon cooling from the melt. Solid-like atoms are detected via the Lindemann ratio. We find that solid-like atoms initiate and grow mainly in the interior of the film and grow outward. Their number increases with decreasing temperature and at a glass transition temperature they dominate in the system to form a relatively rigid glassy state of a thin film shape. We find the existence of a mobile surface layer in both liquid and glassy states which can play an important role in various surface properties of amorphous Ni thin films. We find that glass formation is size independent for models containing 4000 to 108,000 atoms. Moreover, structure of amorphous Ni thin films has been studied in details via coordination number, Honeycutt–Andersen analysis, and density profile which reveal that amorphous thin films exhibit two different parts: interior and surface layer. The former exhibits almost the same structure like that found for the bulk while the latter behaves a more porous structure containing a large amount of undercoordinated sites which are the origin of various surface behaviors of the amorphous Ni or Ni-based thin films found in practice. - Highlights: • Glass formation is analyzed via spatio-temporal arrangements of solid-like atoms. • Amorphous Ni thin film exhibits two different parts: surface and interior. • Mobile surface layer enhances various surface properties of the amorphous Ni thin films. • Undercoordinated sites play an important role in various surface activities.

  2. Multifunctional Parylene-C Microfibrous Thin Films

    Science.gov (United States)

    Chindam, Chandraprakash

    Towards sustainable development, multifunctional products have many advantageous over single-function products: reduction in number of parts, raw material, assembly time, and cost involved in a product's life cycle. My goal for this thesis was to demonstrate the multifunctionalities of Parylene-C microfibrous thin films. To achieve this goal, I chose Parylene C, a polymer, because the fabrication of periodic mediums of Parylene C in the form of microfibrous thin films (muFTFs) was already established. A muFTFs is a parallel arrangement of identical micrometer-sized fibers of shapes cylindrical, chevronic, or helical. Furthermore, Parylene C had three existing functions: in medical-device industries as corrosion-resistive coatings, in electronic industries as electrically insulating coatings, and in biomedical research for tissue-culture substrates. As the functionalities of a material are dependent on the microstructure and physical properties, the investigation made for this thesis was two-fold: (1) Experimentally, I determined the wetting, mechanical, and dielectric properties of columnar muFTFs and examined the microstructural and molecular differences between bulk films and muFTFs. (2) Using physical properties of bulk film, I computationally determined the elastodynamic and determined the electromagnetic filtering capabilities of Parylene-C muFTFs. Several columnar muFTFs of Parylene C were fabricated by varying the monomer deposition angle. Following are the significant experimental findings: 1. Molecular and microstructural characteristics: The dependence of the microfiber inclination angle on the monomer deposition angle was classified into four regimes of two different types. X-ray diffraction experiments indicated that the columnar muFTFs contain three crystal planes not evident in bulk Parylene-C films and that the columnar muFTFs are less crystalline than bulk films. Infrared absorbance spectra revealed that the atomic bonding is the same in all

  3. Fabrication and Film Qualification of Sr Modified Pb(Ca) TiO3 Thin Films

    International Nuclear Information System (INIS)

    Naw Hla Myat San; Khin Aye Thwe; Than Than Win; Yin Maung Maung; Ko Ko Kyaw Soe

    2011-12-01

    Strontium and calcium - modified lead titanate (Pb0.7 Ca0.15 Sr0.15 ) TiO3 (PCST)thin films were prepared by using spin coating technique. Phase transition of PCST was interpreted by means of Er-T characteristics. Process temperature dependence on micro-structure of PCST film was studied. Charge conduction mechanism of PCST thin film was also investigated for film qualification.

  4. Development of neutron diffuse scattering analysis code by thin film and multilayer film

    International Nuclear Information System (INIS)

    Soyama, Kazuhiko

    2004-01-01

    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

  5. Buckling of Thin Films in Nano-Scale

    Directory of Open Access Journals (Sweden)

    Li L.A.

    2010-06-01

    Full Text Available Investigation of thin film buckling is important for life prediction of MEMS device which are damaged mainly by the delamination and buckling of thin films. In this paper the mechanical and thermal properties of compressed thin film titanium films with 150 nm thickness deposited on an organic glass substrate under mechanical and thermal loads were measured and characterized. In order to simulate the thin films which subjected to compound loads and the buckle modes the external uniaxial compression and thermal loading were subjected to the specimen by the symmetric loading device and the electrical film in this experiment. The temperature of the thin film deposited on substrate was measured using thermoelectric couple. The range of temperature accords with the temperature range of the MEMS. It is found that the size and number of the delamination and buckling of the film are depended upon the pre-fixed mechanical loading and thermal temperature. The thermal transient conduction and thermal stability of the film and substrate was studied with finite element method.

  6. Stability of tetraphenyl butadiene thin films in liquid xenon

    International Nuclear Information System (INIS)

    Sanguino, P.; Balau, F.; Botelho do Rego, A.M.; Pereira, A.; Chepel, V.

    2016-01-01

    Tetraphenyl butadiene (TPB) is widely used in particle detectors as a wavelength shifter. In this work we studied the stability of TPB thin films when immersed in liquid xenon (LXe). The thin films were deposited on glass and quartz substrates by thermal evaporation. Morphological and chemical surface properties were monitored before and after immersion into LXe by scanning electron microscopy and X-ray photoelectron spectroscopy. No appreciable changes have been detected with these two methods. Grain size and surface chemical composition were found to be identical before and after submersion into LXe. However, the film thickness, measured via optical transmission in the ultraviolet–visible wavelength regions, decreased by 1.6 μg/cm 2 (24%) after immersion in LXe during 20 h. These results suggest the necessity of using a protective thin film over the Tetraphenyl butadiene when used as a wavelength shifter in LXe particle detectors. - Highlights: • Stability of tetraphenyl butadiene (TPB) thin films immersed in liquid xenon (LXe). • Thermally evaporated TPB thin films were immersed in LXe for 20 h. • Film morphology and chemical surface properties remained unchanged. • Surface density of the films decreased by 1.6 μg/cm 2 (24%) after immersion in LXe. • For using in LXe particle detectors, TPB films should be protected with a coating.

  7. Modification of thin film properties by ion bombardment during deposition

    International Nuclear Information System (INIS)

    Harper, J.M.E.; Cuomo, J.J.; Gambino, R.J.; Kaufman, H.R.

    1984-01-01

    Many thin film deposition techniques involve some form of energetic particle bombardment of the growing film. The degree of bombardment greatly influences the film composition, structure and other properties. While in some techniques the degree of bombardment is secondary to the original process design, in recent years more deposition systems are being designed with the capability for controlled ion bombardment of thin films during deposition. The highest degree of control is obtained with ion beam sources which operate independently of the vapor source providing the thin film material. Other plasma techniques offer varying degrees of control of energetic particle bombardment. Deposition methods involving ion bombardment are described, and the basic processes with which film properties are modified by ion bombardment are summarized. (Auth.)

  8. Electrochromic properties of nanocrystalline MoO3 thin films

    International Nuclear Information System (INIS)

    Hsu, C.-S.; Chan, C.-C.; Huang, H.-T.; Peng, C.-H.; Hsu, W.-C.

    2008-01-01

    Electrochromic MoO 3 thin films were prepared by a sol-gel spin-coating technique. The spin-coated films were initially amorphous; they were calcined, producing nanocrystalline MoO 3 thin films. The effects of annealing temperatures ranging from 100 o C to 500 o C were investigated. The electrochemical and electrochromic properties of the films were measured by cyclic voltammetry and by in-situ optical transmittance techniques in 1 M LiClO 4 /propylene carbonate electrolyte. Experimental results showed that the transmittance of MoO 3 thin films heat-treated at 350 o C varied from 80% to 35% at λ = 550 nm (ΔT = ∼ 45%) and from 86% to 21% at λ ≥ 700 nm (ΔT = ∼ 65%) after coloration. Films heat-treated at 350 deg. C exhibited the best electrochromic properties in the present study

  9. Residual stress in spin-cast polyurethane thin films

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hong; Zhang, Li, E-mail: lizhang@mae.cuhk.edu.hk [Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin N.T., Hong Kong (China); Chow Yuk Ho Technology Centre for Innovative Medicine, The Chinese University of Hong Kong, Shatin N.T., Hong Kong (China)

    2015-01-19

    Residual stress is inevitable during spin-casting. Herein, we report a straightforward method to evaluate the residual stress in as-cast polyurethane thin films using area shrinkage measurement of films in floating state, which shows that the residual stress is independent of radial location on the substrate and decreased with decreasing film thickness below a critical value. We demonstrate that the residual stress is developed due to the solvent evaporation after vitrification during spin-casting and the polymer chains in thin films may undergo vitrification at an increased concentration. The buildup of residual stress in spin-cast polymer films provides an insight into the size effects on the nature of polymer thin films.

  10. 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

  11. Optical modeling and simulation of thin-film photovoltaic devices

    CERN Document Server

    Krc, Janez

    2013-01-01

    In wafer-based and thin-film photovoltaic (PV) devices, the management of light is a crucial aspect of optimization since trapping sunlight in active parts of PV devices is essential for efficient energy conversions. Optical modeling and simulation enable efficient analysis and optimization of the optical situation in optoelectronic and PV devices. Optical Modeling and Simulation of Thin-Film Photovoltaic Devices provides readers with a thorough guide to performing optical modeling and simulations of thin-film solar cells and PV modules. It offers insight on examples of existing optical models

  12. The state of the art of thin-film photovoltaics

    International Nuclear Information System (INIS)

    Surek, T.

    1993-10-01

    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

  13. Thin film circuits for future applications. Pt. 2. Evaporation technique

    Energy Technology Data Exchange (ETDEWEB)

    Haug, G; Houska, K H; Schmidt, H J; Sprengel, H P; Wohak, K

    1976-06-01

    Investigations of thin film diffusion processes and reactions with encapsulation materials resulted in improved long term stability of evaporated NiCr resistors, SiO capacitors and NiCr/Au conductors for thin film circuits. Stable NiCr resistor networks can be formed on ceramic substrates, and SiO capacitors of good quality can be deposited on the new very smooth ceramic substrates. The knowledge of the influence of evaporation parameters make the production of SiO capacitors with definite properties and good reproducibility possible. The range of capacitance of tantalum thin film circuits can be extended by integration with evaporated SiO capacitors.

  14. XRay Study of Transfer Printed Pentacene Thin Films

    International Nuclear Information System (INIS)

    Shao, Y.; Solin, S. A.; Hines, D. R.; Williams, E. D.

    2007-01-01

    We investigated the structural properties and transfer properties of pentacene thin films fabricated by thermal deposition and transfer printing onto SiO2 and plastic substrates, respectively. The dependence of the crystallite size on the printing time, temperature and pressure were measured. The increases of crystalline size were observed when pentacene thin films were printed under specific conditions, e.g. 120 deg. C and 600 psi and can be correlated with the improvement of the field effect mobility of pentacene thin-film transistors

  15. Optical properties of CeO 2 thin films

    Indian Academy of Sciences (India)

    Cerium oxide (CeO2) thin films have been prepared by electron beam evaporation technique onto glass substrate at a pressure of about 6 × 10-6 Torr. The thickness of CeO2 films ranges from 140–180 nm. The optical properties of cerium oxide films are studied in the wavelength range of 200–850 nm. The film is highly ...

  16. Principles of electron backscattering by solids and thin films

    International Nuclear Information System (INIS)

    Niedrig, H.

    1977-01-01

    The parameters concerning the electron backscattering from thin films and solids (atomic scattering cross-section, atomic number, single/multiple scattering, film thickness of self-supporting films and of surface films on bulk substrates, scattering angular distribution, angle of incidence, diffraction effects) are described. Their influence on some important contrast mechanisms in scanning electron microscopy (thickness contrast, Z/material contrast, tilting/topography contrast, orientation contrast) is discussed. The main backscattering electron detection systems are briefly described. (orig.) [de

  17. Optical spectroscopic study of multiferroic BiFeO3 and LuFe2O4

    Science.gov (United States)

    Xu, Xiaoshan

    2010-03-01

    Iron-based multiferroics such as BiFeO3 and LuFe2O4 exhibit the highest magnetic and ferroelectric ordering temperatures among known multiferroics. LuFe2O4 is a frustrated system with several phase transitions that result in electronically driven multiferroicity. To understand how this peculiar multiferroic mechanism correlates with magnetism, we studied electronic excitations by optical spectroscopy and other complementary techniques. We show that the charge order, which determines the dielectric properties, is due to the ``order by fluctuation'' mechanism, evidenced by the onset of charge fluctuation well below the charge ordering transition. We also find a low temperature monoclinic distortion driven by both temperature and magnetic field, indicating strong coupling between structure, magnetism and charge order. BiFeO3 is the only known single phase multiferroics with room temperature magnetism and ferroelectricity. To investigate the spin-charge coupling, we measured the optical properties of BiFeO3. We find that the absorption onset occurs due to on-site Fe^3+ excitations at 1.41 and 1.90 eV. Temperature and magnetic-field-induced spectral changes reveal complex interactions between on-site crystal-field and magnetic excitations in the form of magnon sidebands. The sensitivity of the magnon sidebands allows us to map out the magnetic-field temperature phase diagram which demonstrates optical evidence for spin spiral quenching above 20 T and suggests a spin domain reorientation near 10 T. Work done in collaboration with T.V. Brinzari, R.C. Rai, M. Angst, R.P. Hermann, A.D. Christianson, J.-W. Kim, Z. Islam, B.C. Sales, D. Mandrus, S. Lee, Y.H. Chu, L. W. Martin, A. Kumar, R. Ramesh, S.W. Cheong, S. McGill, and J.L. Musfeldt.

  18. Dewetting of thin polymer film on rough substrate: II. Experiment

    International Nuclear Information System (INIS)

    Volodin, Pylyp; Kondyurin, Alexey

    2008-01-01

    The theory of the dewetting process developed for a model of substrate-film interaction forces was examined by an experimental investigation of the dewetting process of thin polystyrene (PS) films on chemically etched silicon substrates. In the dependence on PS films thickness and silicon roughness, various situations of dewetting were observed as follows: (i) if the wavelength of the substrate roughness is much larger than the critical spinodal wavelength of a film, then spinodal dewetting of the film is observed; (ii) if the wavelength of the substrate roughness is smaller than the critical wavelength of the film and the substrate roughness is larger in comparison with film thickness, then the dewetting due to substrate roughness is observed and the dewetted film patterns repeat the rough substrate structure; (iii) if the wavelength of the substrate roughness is smaller than the critical wavelength of the film and the substrate roughness is small in comparison with the film thickness, then spinodal dewetting proceeds

  19. Ideal glass transitions in thin films: An energy landscape perspective

    Science.gov (United States)

    Truskett, Thomas M.; Ganesan, Venkat

    2003-07-01

    We introduce a mean-field model for the potential energy landscape of a thin fluid film confined between parallel substrates. The model predicts how the number of accessible basins on the energy landscape and, consequently, the film's ideal glass transition temperature depend on bulk pressure, film thickness, and the strength of the fluid-fluid and fluid-substrate interactions. The predictions are in qualitative agreement with the experimental trends for the kinetic glass transition temperature of thin films, suggesting the utility of landscape-based approaches for studying the behavior of confined fluids.

  20. Strain Relaxation and Vacancy Creation in Thin Platinum Films

    International Nuclear Information System (INIS)

    Gruber, W.; Chakravarty, S.; Schmidt, H.; Baehtz, C.; Leitenberger, W.; Bruns, M.; Kobler, A.; Kuebel, C.

    2011-01-01

    Synchrotron based combined in situ x-ray diffractometry and reflectometry is used to investigate the role of vacancies for the relaxation of residual stress in thin metallic Pt films. From the experimentally determined relative changes of the lattice parameter a and of the film thickness L the modification of vacancy concentration and residual strain was derived as a function of annealing time at 130 deg. C. The results indicate that relaxation of strain resulting from compressive stress is accompanied by the creation of vacancies at the free film surface. This proves experimentally the postulated dominant role of vacancies for stress relaxation in thin metal films close to room temperature.

  1. Soft Magnetic Multilayered Thin Films for HF Applications

    Science.gov (United States)

    Loizos, George; Giannopoulos, George; Serletis, Christos; Maity, Tuhin; Roy, Saibal; Lupu, Nicoleta; Kijima, Hanae; Yamaguchi, Masahiro; Niarchos, Dimitris

    Multilayered thin films from various soft magnetic materials were successfully prepared by magnetron sputtering in Ar atmosphere. The magnetic properties and microstructure were investigated. It is found that the films show good soft magnetic properties: magnetic coercivity of 1-10 Oe and saturation magnetization higher than 1T. The initial permeability of the films is greater than 300 and flattens up to 600 MHz. The multilayer thin film properties in combination with their easy, fast and reproducible fabrication indicate that they are potential candidates for high frequency applications.

  2. Microwave Josephson generation in thin film superconducting bridges

    International Nuclear Information System (INIS)

    Gubankov, V.N.; Koshelets, V.P.; Ovsyannikov, G.A.

    1975-01-01

    Thin-film bridges have some advantage over other types of superconducting weak links: good definition of electromagnetic parameters and of weak region geometry. Up to now Josephson properties of bridges have been investigated by using indirect methods (the effect of magnetic field on the critical current I 0 , the bridge behavior in a microwave field, etc.). Direct experimental observation of Josephson radiation from autonomous thin film bridges is reported. Microwave radiation in tin bridges of 'variable' thickness has been investigated where the thickness of the film forming the bridge is far less than the thickness of the bank films. (Auth.)

  3. Photoinduced hydrophobic surface of graphene oxide thin films

    International Nuclear Information System (INIS)

    Zhang Xiaoyan; Song Peng; Cui Xiaoli

    2012-01-01

    Graphene oxide (GO) thin films were deposited on transparent conducting oxide substrates and glass slides by spin coating method at room temperature. The wettability of GO thin films before and after ultraviolet (UV) irradiation was characterized with water contact angles, which increased from 27.3° to 57.6° after 3 h of irradiation, indicating a photo-induced hydrophobic surface. The UV–vis absorption spectra, Raman spectroscopy, X-ray photoelectron spectroscopy, and conductivity measurements of GO films before and after UV irradiation were taken to study the mechanism of photoinduced hydrophobic surface of GO thin films. It is demonstrated that the photoinduced hydrophobic surface is ascribed to the elimination of oxygen-containing functional groups on GO molecules. This work provides a simple strategy to control the wettability properties of GO thin films by UV irradiation. - Highlights: ► Photoinduced hydrophobic surface of graphene oxide thin films has been demonstrated. ► Elimination of oxygen-containing functional groups in graphene oxide achieved by UV irradiation. ► We provide novel strategy to control surface wettability of GO thin films by UV irradiation.

  4. Tools to synthesize the learning of thin films

    International Nuclear Information System (INIS)

    Rojas, Roberto; Fuster, Gonzalo; Sluesarenko, Viktor

    2011-01-01

    After a review of textbooks written for undergraduate courses in physics, we have found that discussions on thin films are mostly incomplete. They consider the reflected and not the transmitted light for two instead of the four types of thin films. In this work, we complement the discussion in elementary textbooks, by analysing the phase differences required to match the conditions for constructive and destructive interference, in the reflected and transmitted light in four types of thin films. We consider thin films with varied sequences in the refractive index, which we identify as barriers, wells and stairs (up and down). Also, we use the conservation of energy in order to understand the complementary colour fringes observed in the reflected and transmitted light through thin films. We analyse systematically the phase changes by introducing a phase table and we synthesize the results in a circular diagram matching 16 physical situations of interference and their corresponding conditions on the film thickness. The phase table and the circular diagram are a pair of tools easily assimilated by students, and useful to organize, analyse and activate the knowledge about thin films.

  5. Thin Films for X-ray Optics

    Science.gov (United States)

    Conley, Raymond

    Focusing x-rays with refraction requires an entire array of lens instead of a single element, each contributing a minute amount of focusing to the system. In contrast to their visible light counterparts, diffractive optics require a certain depth along the optical axis in order to provide sufficient phase shift. Mirrors reflect only at very shallow angles. In order to increase the angle of incidence, contribution from constructive interference within many layers needs to be collected. This requires a multilayer coating. Thin films have become a central ingredient for many x-ray optics due to the ease of which material composition and thickness can be controlled. Chapter 1 starts with a short introduction and survey of the field of x-ray optics. This begins with an explanation of reflective multilayers. Focusing optics are presented next, including mirrors, zone plates, refractive lenses, and multilayer Laue lens (MLL). The strengths and weaknesses of each "species" of optic are briefly discussed, alongside fabrication issues and the ultimate performance for each. Practical considerations on the use of thin-films for x-ray optics fabrication span a wide array of topics including material systems selection and instrumentation design. Sputter deposition is utilized exclusively for the work included herein because this method of thin-film deposition allows a wide array of deposition parameters to be controlled. This chapter also includes a short description of two deposition systems I have designed. Chapter 2 covers a small sampling of some of my work on reflective multilayers, and outlines two of the deposition systems I have designed and built at the Advanced Photon Source. A three-stripe double multilayer monochromator is presented as a case study in order to detail specifications, fabrication, and performance of this prolific breed of x-ray optics. The APS Rotary Deposition System was the first deposition system in the world designed specifically for multilayer

  6. Specific features of nonlinear optical properties of Eu3+ doped BiFeO3 nanopowders near antiferromagnetic transition

    Science.gov (United States)

    El Bahraoui, T.; Sekkati, M.; Taibi, M.; Abd-Lefdil, M.; El-Naggar, A. M.; AlZayed, N. S.; Albassam, A. A.; Kityk, I. V.; Maciag, A.

    2016-01-01

    The monitoring of the Eu3+ doped BiFeO3 nanopowders was performed near the antiferromagnetic transformation by photoinduced optical second harmonic generation. As photoinduced laser beams we have used bicolor coherent excitations of the Er:glass laser emitting at 1540 nm with frequency repetition about 15 ns. The studies of the photoinduced SHG were performed versus temperature including the temperature range of ferromagnetic-ferroelectric transition (350 °C…390 °C). The optimal light polarization and intensity ratio were chosen; the sensitivity of the photoinduced SHG to the multiferroic phase transitions was explored.

  7. The synthesis, structure and reactivity of iron-bismuth complexes : Potential Molecular Precursors for Multiferroic BiFeO3

    OpenAIRE

    Wójcik, Katarzyna

    2009-01-01

    The thesis presented here is focused on the synthesis of iron-bismuth alkoxides and siloxides as precursors for multiferroic BiFeO3 systems. Spectrum of novel cyclopentadienyl substituted iron-bismuth complexes of the general type [{Cpy(CO)2Fe}BiX2], as potential precursors for cyclopentadienyl iron-bismuth alkoxides or siloxides [{Cpy(CO)2Fe}Bi(OR)2] (R-OtBu, OSiMe2tBu), were obtained and characterised. The use of wide range of cyclopentadienyl rings in the iron carbonyl compounds allowed fo...

  8. Thermionic vacuum arc (TVA) technique for magnesium thin film deposition

    Energy Technology Data Exchange (ETDEWEB)

    Balbag, M.Z., E-mail: zbalbag@ogu.edu.t [Eskisehir Osmangazi University, Education Faculty, Primary Education, Meselik Campus, Eskisehir 26480 (Turkey); Pat, S.; Ozkan, M.; Ekem, N. [Eskisehir Osmangazi University, Art and Science Faculty, Physics Department, Eskisehir 26480 (Turkey); Musa, G. [Ovidius University, Physics Department, Constanta (Romania)

    2010-08-15

    In this study, magnesium thin films were deposited on glass substrate by the Thermionic Vacuum Arc (TVA) technique for the first time. We present a different technique for deposition of high-quality magnesium thin films. By means of this technique, the production of films is achieved by condensing the plasma of anode material generated using Thermionic Vacuum Arc (TVA) under high vacuum conditions onto the surface to be coated. The crystal orientation and morphology of the deposited films were investigated by using XRD, EDX, SEM and AFM. The aim of this study is to search the use of TVA technique to coat magnesium thin films and to determine some of the physical properties of the films generated. Furthermore, this study will contribute to the scientific studies which search the thin films of magnesium or the compounds containing magnesium. In future, this study will be preliminary work to entirely produce magnesium diboride (MgB{sub 2}) superconductor thin film with the TVA technique.

  9. ITO thin films deposited by advanced pulsed laser deposition

    International Nuclear Information System (INIS)

    Viespe, Cristian; Nicolae, Ionut; Sima, Cornelia; Grigoriu, Constantin; Medianu, Rares

    2007-01-01

    Indium tin oxide thin films were deposited by computer assisted advanced PLD method in order to obtain transparent, conductive and homogeneous films on a large area. The films were deposited on glass substrates. We studied the influence of the temperature (room temperature (RT)-180 deg. C), pressure (1-6 x 10 -2 Torr), laser fluence (1-4 J/cm 2 ) and wavelength (266-355 nm) on the film properties. The deposition rate, roughness, film structure, optical transmission, electrical conductivity measurements were done. We deposited uniform ITO thin films (thickness 100-600 nm, roughness 5-10 nm) between RT and 180 deg. C on a large area (5 x 5 cm 2 ). The films have electrical resistivity of 8 x 10 -4 Ω cm at RT, 5 x 10 -4 Ω cm at 180 deg. C and an optical transmission in the visible range, around 89%

  10. Broadband back grating design for thin film solar cells

    KAUST Repository

    Janjua, Bilal; Jabbour, Ghassan E.

    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.

  11. Laser-Printed Organic Thin-Film Transistors

    KAUST Repository

    Diemer, Peter J.; Harper, Angela F.; Niazi, Muhammad Rizwan; Petty, Anthony J.; Anthony, John E.; Amassian, Aram; Jurchescu, Oana D.

    2017-01-01

    their incorporation in large-scale manufacturing processes. Here, the first ever organic thin-film transistor fabricated with an electrophotographic laser printing process using a standard office laser printer is reported. This completely solvent-free additive

  12. Preparation of Nb thin films with bulk transition temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Peirce, L H [Florida State Univ., Tallahassee (USA). Dept. of Physics

    1984-08-01

    Thin films (1000-2000 A) of Nb were prepared with bulk transition temperatures (9.25 K) by evaporation from an electron gun. Necessary substrate temperatures, evaporation rates and H/sub 2/O pressures were determined.

  13. A Variational approach to thin film hydrodynamics of binary mixtures

    KAUST Repository

    Xu, Xinpeng; Thiele, Uwe; Qian, Tiezheng

    2015-01-01

    In order to model the dynamics of thin films of mixtures, solutions, and suspensions, a thermodynamically consistent formulation is needed such that various coexisting dissipative processes with cross couplings can be correctly described

  14. Chemical solution deposition of functional oxide thin films

    CERN Document Server

    Schneller, Theodor; Kosec, Marija

    2014-01-01

    Chemical Solution Deposition (CSD) is a highly-flexible and inexpensive technique for the fabrication of functional oxide thin films. Featuring nearly 400 illustrations, this text covers all aspects of the technique.

  15. Mechanism of spontaneous hole formation in thin polymeric films

    DEFF Research Database (Denmark)

    Yu, Kaijia; Rasmussen, Henrik K.; Román Marín, José Manuel

    2012-01-01

    We show computationally that (molten) thin polymeric film containing nonequilibrium configurations originating from a solvent evaporation may develop holes spontaneously in the molten state, and that they appear delayed. Polymers above the glass transition temperature are liquids where the flow...

  16. Simple gun for vapor deposition of organic thin films

    International Nuclear Information System (INIS)

    Sato, N.; Seki, K.; Inokuchi, H.

    1987-01-01

    A simple evaporation gun for preparing organic thin films was fabricated using commercially available parts of an electron gun for a TV Braun tube. The device permits sample heating to be easily controlled because of the small heat capacity

  17. Multiferroic iron oxide thin films at room temperature

    Czech Academy of Sciences Publication Activity Database

    Gich, M.; Fina, I.; Morelli, Alessio; Sánchez, F.; Alexe, M.; Gazquez, J.; Fontcuberta, J.; Roig, A.

    2014-01-01

    Roč. 26, č. 27 (2014), s. 4645-4652 ISSN 0935-9648 Institutional support: RVO:68378271 Keywords : multiferroic * iron oxide * thin film Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 17.493, year: 2014

  18. Bandtail characteristics in InN thin films

    International Nuclear Information System (INIS)

    Shen, W.Z.; Jiang, L.F.; Yang, H.F.; Meng, F.Y.; Ogawa, H.; Guo, Q.X.

    2002-01-01

    The Urbach bandtail characteristics in InN thin films grown by radio-frequency magnetron sputtering on sapphire (0001) substrates have been investigated both theoretically and experimentally. The bandtail parameter in InN thin films has been obtained by temperature-dependent transmission spectra, with the aid of a detailed calculation of the transmission profile. A bandtail model based on the calculation of density of occupied states and the carrier-phonon interaction has been employed to analyze the temperature-dependent bandtail characteristics. The bandtail parameter is in the range of 90-120 meV in the InN thin film. It is found that the carrier-phonon interaction in InN is weak and the structural disorder contribution (∼90 meV) dominates over the interactive terms. The high structural disorder in InN thin films may relate to the high nonradiative recombination centers

  19. High Performance Thin-Film Composite Forward Osmosis Membrane

    KAUST Repository

    Yip, Ngai Yin; Tiraferri, Alberto; Phillip, William A.; Schiffman, Jessica D.; Elimelech, Menachem

    2010-01-01

    obstacle hindering further advancements of this technology. This work presents the development of a high performance thin-film composite membrane for forward osmosis applications. The membrane consists of a selective polyamide active layer formed

  20. A thin film hydroponic system for plant studies

    Science.gov (United States)

    Hines, Robert; Prince, Ralph; Muller, Eldon; Schuerger, Andrew

    1990-01-01

    The Land Pavillion, EPCOT Center, houses a hydroponic, thin film growing system identical to that residing in NASA's Biomass Production Chamber at Kennedy Space Center. The system is targeted for plant disease and nutrition studies. The system is described.

  1. Phonon transport across nano-scale curved thin films

    Energy Technology Data Exchange (ETDEWEB)

    Mansoor, Saad B.; Yilbas, Bekir S., E-mail: bsyilbas@kfupm.edu.sa

    2016-12-15

    Phonon transport across the curve thin silicon film due to temperature disturbance at film edges is examined. The equation for radiative transport is considered via incorporating Boltzmann transport equation for the energy transfer. The effect of the thin film curvature on phonon transport characteristics is assessed. In the analysis, the film arc length along the film centerline is considered to be constant and the film arc angle is varied to obtain various film curvatures. Equivalent equilibrium temperature is introduced to assess the phonon intensity distribution inside the curved thin film. It is found that equivalent equilibrium temperature decay along the arc length is sharper than that of in the radial direction, which is more pronounced in the region close to the film inner radius. Reducing film arc angle increases the film curvature; in which case, phonon intensity decay becomes sharp in the close region of the high temperature edge. Equivalent equilibrium temperature demonstrates non-symmetric distribution along the radial direction, which is more pronounced in the near region of the high temperature edge.

  2. Phonon transport across nano-scale curved thin films

    International Nuclear Information System (INIS)

    Mansoor, Saad B.; Yilbas, Bekir S.

    2016-01-01

    Phonon transport across the curve thin silicon film due to temperature disturbance at film edges is examined. The equation for radiative transport is considered via incorporating Boltzmann transport equation for the energy transfer. The effect of the thin film curvature on phonon transport characteristics is assessed. In the analysis, the film arc length along the film centerline is considered to be constant and the film arc angle is varied to obtain various film curvatures. Equivalent equilibrium temperature is introduced to assess the phonon intensity distribution inside the curved thin film. It is found that equivalent equilibrium temperature decay along the arc length is sharper than that of in the radial direction, which is more pronounced in the region close to the film inner radius. Reducing film arc angle increases the film curvature; in which case, phonon intensity decay becomes sharp in the close region of the high temperature edge. Equivalent equilibrium temperature demonstrates non-symmetric distribution along the radial direction, which is more pronounced in the near region of the high temperature edge.

  3. Inverse bilayer magnetoelectric thin film sensor

    Energy Technology Data Exchange (ETDEWEB)

    Yarar, E.; Piorra, A.; Quandt, E., E-mail: eq@tf.uni-kiel.de [Chair for Inorganic Functional Materials, Institute for Materials Science, Faculty of Engineering, Kiel University, Kaiserstraße 2, D-24143 Kiel (Germany); Salzer, S.; Höft, M.; Knöchel, R. [Microwave Laboratory, Institute of Electrical and Information Engineering, Faculty of Engineering, Kiel University, Kaiserstraße 2, D-24143 Kiel (Germany); Hrkac, V.; Kienle, L. [Chair for Synthesis and Real Structure, Institute for Materials Science, Faculty of Engineering, Kiel University, Kaiserstraße 2, D-24143 Kiel (Germany)

    2016-07-11

    Prior investigations on magnetoelectric (ME) thin film sensors using amorphous FeCoSiB as a magnetostrictive layer and AlN as a piezoelectric layer revealed a limit of detection (LOD) in the range of a few pT/Hz{sup 1/2} in the mechanical resonance. These sensors are comprised of a Si/SiO{sub 2}/Pt/AlN/FeCoSiB layer stack, as dictated by the temperatures required for the deposition of the layers. A low temperature deposition route of very high quality AlN allows the reversal of the deposition sequence, thus allowing the amorphous FeCoSiB to be deposited on the very smooth Si substrate. As a consequence, the LOD could be enhanced by almost an order of magnitude reaching 400 fT/Hz{sup 1/2} at the mechanical resonance of the sensor. Giant ME coefficients (α{sub ME}) as high as 5 kV/cm Oe were measured. Transmission electron microscopy investigations revealed highly c-axis oriented growth of the AlN starting from the Pt-AlN interface with local epitaxy.

  4. Degradation analysis of thin film photovoltaic modules

    International Nuclear Information System (INIS)

    Radue, C.; Dyk, E.E. van

    2009-01-01

    Five thin film photovoltaic modules were deployed outdoors under open circuit conditions after a thorough indoor evaluation. Two technology types were investigated: amorphous silicon (a-Si:H) and copper indium gallium diselenide (CIGS). Two 14 W a-Si:H modules, labelled Si-1 and Si-2, were investigated. Both exhibited degradation, initially due to the well-known light-induced degradation described by Staebler and Wronski [Applied Physics Letters 31 (4) (1977) 292], and thereafter due to other degradation modes such as cell degradation. The various degradation modes contributing to the degradation of the a-Si:H modules will be discussed. The initial maximum power output (P MAX ) of Si-1 was 9.92 W, with the initial light-induced degradation for Si-1 ∼30% and a total degradation of ∼42%. For Si-2 the initial P MAX was 7.93 W, with initial light-induced degradation of ∼10% and a total degradation of ∼17%. Three CIGS modules were investigated: two 20 W modules labelled CIGS-1 and CIGS-2, and a 40 W module labelled CIGS-3. CIGS-2 exhibited stable performance while CIGS-1 and CIGS-3 exhibited degradation. CIGS is known to be stable over long periods of time, and thus the possible reasons for the degradation of the two modules are discussed.

  5. Degradation analysis of thin film photovoltaic modules

    Energy Technology Data Exchange (ETDEWEB)

    Radue, C., E-mail: chantelle.radue@nmmu.ac.z [Department of Physics, PO Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa); Dyk, E.E. van [Department of Physics, PO Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa)

    2009-12-01

    Five thin film photovoltaic modules were deployed outdoors under open circuit conditions after a thorough indoor evaluation. Two technology types were investigated: amorphous silicon (a-Si:H) and copper indium gallium diselenide (CIGS). Two 14 W a-Si:H modules, labelled Si-1 and Si-2, were investigated. Both exhibited degradation, initially due to the well-known light-induced degradation described by Staebler and Wronski [Applied Physics Letters 31 (4) (1977) 292], and thereafter due to other degradation modes such as cell degradation. The various degradation modes contributing to the degradation of the a-Si:H modules will be discussed. The initial maximum power output (P{sub MAX}) of Si-1 was 9.92 W, with the initial light-induced degradation for Si-1 approx30% and a total degradation of approx42%. For Si-2 the initial P{sub MAX} was 7.93 W, with initial light-induced degradation of approx10% and a total degradation of approx17%. Three CIGS modules were investigated: two 20 W modules labelled CIGS-1 and CIGS-2, and a 40 W module labelled CIGS-3. CIGS-2 exhibited stable performance while CIGS-1 and CIGS-3 exhibited degradation. CIGS is known to be stable over long periods of time, and thus the possible reasons for the degradation of the two modules are discussed.

  6. Product reliability and thin-film photovoltaics

    Science.gov (United States)

    Gaston, Ryan; Feist, Rebekah; Yeung, Simon; Hus, Mike; Bernius, Mark; Langlois, Marc; Bury, Scott; Granata, Jennifer; Quintana, Michael; Carlson, Carl; Sarakakis, Georgios; Ogden, Douglas; Mettas, Adamantios

    2009-08-01

    Despite significant growth in photovoltaics (PV) over the last few years, only approximately 1.07 billion kWhr of electricity is estimated to have been generated from PV in the US during 2008, or 0.27% of total electrical generation. PV market penetration is set for a paradigm shift, as fluctuating hydrocarbon prices and an acknowledgement of the environmental impacts associated with their use, combined with breakthrough new PV technologies, such as thin-film and BIPV, are driving the cost of energy generated with PV to parity or cost advantage versus more traditional forms of energy generation. In addition to reaching cost parity with grid supplied power, a key to the long-term success of PV as a viable energy alternative is the reliability of systems in the field. New technologies may or may not have the same failure modes as previous technologies. Reliability testing and product lifetime issues continue to be one of the key bottlenecks in the rapid commercialization of PV technologies today. In this paper, we highlight the critical need for moving away from relying on traditional qualification and safety tests as a measure of reliability and focus instead on designing for reliability and its integration into the product development process. A drive towards quantitative predictive accelerated testing is emphasized and an industrial collaboration model addressing reliability challenges is proposed.

  7. Magnetostatic excitations in thin ferrite films

    International Nuclear Information System (INIS)

    Zil'berman, P.E.; Lugovskoi, A.V.

    1987-01-01

    The authors discuss the influence of the exchange interaction and dissipative processes in thin ferrite films on the eigenfrequency spectrum of magnetostatic standing waves and on the dispersion relation and attenuation of magnetostatic traveling waves. For the first time they obtain explicitly the dispersion relation for magnetostatic waves (MSWs) in a tangential saturating magnetic field H 0 to second order (inclusive) in the exchange interaction parameter λ. The authors obtain computer solutions for this equation in the complex frequency (ω) plane (for standing waves) or wave-number (q) plane (for traveling waves). The authors show that the dispersion relation constructed from the standing-wave spectrum is different from that of the traveling waves if λ≠0, even if dissipation is neglected. The traveling waves have auxiliary branches of the dispersion relation with weak damping near the spin-wave-resonance (SWR) frequencies. Dissipation has only a relatively weak effect on the frequency spectrum of the standing waves, shifting it upward. For the traveling waves, however, dissipation leads to qualitative changes in the structure of the dispersion relation, giving rise to new branches, forbidden bands, reentrant and anomalous-dispersion regions

  8. Thin film deposition using rarefied gas jet

    Science.gov (United States)

    Pradhan, Sahadev, , Dr.

    2017-06-01

    The rarefied gas jet of aluminium is studied at Mach number Ma = (Uj /√{ kbTj / mg }) in the range .01 PVD) process for the development of the highly oriented pure metallic aluminum thin film with uniform thickness and strong adhesion on the surface of the substrate in the form of ionic plasma, so that the substrate can be protected from corrosion and oxidation and thereby enhance the lifetime and safety, and to introduce the desired surface properties for a given application. Here, H is the characteristic dimension, U_j and T_j are the jet velocity and temperature, n_d is the number density of the jet, m and d are the molecular mass and diameter, and kbis the Boltzmann constant. An important finding is that the capture width (cross-section of the gas jet deposited on the substrate) is symmetric around the centerline of the substrate, and decreases with increased Mach number due to an increase in the momentum of the gas molecules. DSMC simulation results reveals that at low Knudsen number ((Kn=0.01); shorter mean free paths), the atoms experience more collisions, which direct them toward the substrate. However, the atoms also move with lower momentum at low Mach number, which allows scattering collisions to rapidly direct the atoms to the substrate.

  9. Nanopolar reorientation in ferroelectric thin films

    International Nuclear Information System (INIS)

    Hubert, C.; Levy, J.; Rivkin, T. V.; Carlson, C.; Parilla, P. A.; Perkins, J. D.; Ginley, D. S.

    2001-01-01

    The influence of varying oxygen pressure P(O 2 ) during the growth of Ba 0.4 Sr 0.6 TiO 3 thin films is investigated using dielectric and local optical probes. A transition from in-plane to out-of-plane ferroelectricity is observed with increasing P(O 2 ). Signatures of in-plane and out-of-plane ferroelectricity are identified using dielectric response and time-resolved confocal scanning optical microscopy (TRCSOM). At the crossover pressure between in-plane and out-of-plane polarization (P c =85 mTorr), TRCSOM measurements reveal a soft, highly dispersive out-of-plane polarization that reorients in plane under modest applied electric fields. At higher deposition pressures, the out-of-plane polarization is hardened and is less dispersive at microwave frequencies, and the dielectric tuning is suppressed. Nanopolar reorientation is believed to be responsible for the marked increase in dielectric tuning at P(O 2 )=P c

  10. Trends and new applications in thin films

    International Nuclear Information System (INIS)

    1996-01-01

    The proceedings of this symposium comprise 95 communications from which 64 were selected and fall into the scope of INIS subject categories, and 1 was selected for ETDE indexing. The selected communications deal with the techniques used for thin films preparation using chemical or physical vapor deposition techniques (plasma-arc or jet spraying, cathode sputtering, reactive DC or RF magnetron sputtering, plasma-ion deposition, ion implantation, electron or ion beam spraying, ion beam assisted plasma etching, dynamic ion mixing, distributed electron cyclotron resonance plasma sputtering, laser induced plasma sputtering etc..). The effects and interactions with the substrates (ion implantation, crystal growth, crystal-phase transformations, microstructures, penetration depth, changes in lattice parameters etc..) are analysed using various techniques such as grazing incidence X-ray diffraction, X-ray reflectometry, X-ray and angle resolved electron spectroscopy, Auger electron spectroscopy, Rutherford backscattering spectroscopy, SEM, TEM, IR absorption spectroscopy, UV or visible emission spectroscopy, conversion electron Moessbauer spectroscopy, X-ray fluorescence, mass spectroscopy, optical ellipsometry etc.. Mechanical tests such as scratch, microhardness and wear tests are also performed on the coatings to analyse their mechanical properties. (J.S.)

  11. Lasing in liquid crystal thin films

    Energy Technology Data Exchange (ETDEWEB)

    Palto, S. P. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)], E-mail: palto@online.ru

    2006-09-15

    A lasing condition is formulated in matrix form for optically anisotropic thin films. Lasing behavior of liquid-crystal slabs is analyzed. In particular, it is shown that if the spatial extent of a liquid crystal slab is much larger than its thickness, then laser emission is feasible not only along the normal to the slab, but also in the entire angular sector. The generated laser light can be observed experimentally as a spot or as concentric rings on a screen. The lowest lasing threshold corresponds to in-plane sliding modes leaking into the substrate. The feedback required for lasing is provided by reflection from the interfaces, rather than edges, of the liquid-crystal slab operating as a planar Fabry-Perot cavity. For cholesteric liquid crystals, it is shown that energy loss to the sliding modes leaking into the substrates and escaping through their edges is a key factor that limits the efficiency of band-edge emission along the normal to the slab.

  12. Silicon Thin-Film Solar Cells

    Directory of Open Access Journals (Sweden)

    Guy Beaucarne

    2007-01-01

    with plasma-enhanced chemical vapor deposition (PECVD. In spite of the fundamental limitation of this material due to its disorder and metastability, the technology is now gaining industrial momentum thanks to the entry of equipment manufacturers with experience with large-area PECVD. Microcrystalline Si (also called nanocrystalline Si is a material with crystallites in the nanometer range in an amorphous matrix, and which contains less defects than amorphous silicon. Its lower bandgap makes it particularly appropriate as active material for the bottom cell in tandem and triple junction devices. The combination of an amorphous silicon top cell and a microcrystalline bottom cell has yielded promising results, but much work is needed to implement it on large-area and to limit light-induced degradation. Finally thin-film polysilicon solar cells, with grain size in the micrometer range, has recently emerged as an alternative photovoltaic technology. The layers have a grain size ranging from 1 μm to several tens of microns, and are formed at a temperature ranging from 600 to more than 1000∘C. Solid Phase Crystallization has yielded the best results so far but there has recently been fast progress with seed layer approaches, particularly those using the aluminum-induced crystallization technique.

  13. Nanostructured refractory thin films for solar applications

    Science.gov (United States)

    Ollier, E.; Dunoyer, N.; Dellea, O.; Szambolics, H.

    2014-08-01

    Selective solar absorbers are key elements of all solar thermal systems. Solar thermal panels and Concentrated Solar Power (CSP) systems aim respectively at producing heat and electricity. In both cases, a surface receives the solar radiation and is designed to have the highest optical absorption (lowest optical reflectivity) of the solar radiation in the visible wavelength range where the solar intensity is the highest. It also has a low emissivity in the infrared (IR) range in order to avoid radiative thermal losses. Current solutions in the state of the art usually consist in deposited interferential thin films or in cermets [1]. Structured surfaces have been proposed and have been simulated because they are supposed to be more efficient when the solar radiation is not normal to the receiving surface and because they could potentially be fabricated with refractory materials able to sustain high operating temperatures. This work presents a new method to fabricate micro/nanostructured surfaces on molybdenum (refractory metal with a melting temperature of 2623°C). This method now allows obtaining a refractory selective surface with an excellent optical selectivity and a very high absorption in the visible range. This high absorption performance was obtained by achieving a double structuration at micro and nano scales thanks to an innovative process flow.

  14. Properties of Spray Pyrolysied Copper Oxide Thin Films

    Directory of Open Access Journals (Sweden)

    S. S. Roy

    2017-02-01

    Full Text Available Copper oxide (CuO thin films were deposited on well cleaned glass substrates by spray pyrolysis technique (SPT from cupric acetate (Cu(CH3COO2.H2O precursor solutions of 0.05 – 0.15 M molar concentrations (MC at a substrate temperature of 350 °C and at an air pressure of 1 bar. Effect of varying MC on the surface morphology, structural optical and electrical properties of CuO thin films were investigated. XRD patterns of the prepared films revealed the formation of CuO thin films having monoclinic structure with the main CuO (111 orientation and crystalline size ranging from 8.02 to 9.05 nm was observed. The optical transmission of the film was found to decrease with the increase of MC. The optical band gap of the thin films for 0.10 M was fond to be 1.60 eV. The room temperature electrical resistivity varies from 31 and 24 ohm.cm for the films grown with MC of 0.05 and 0.10 M respectively. The change in resistivity of the films was studied with respect to the change in temperature was shown that semiconductor nature is present. This information is expected to underlie the successful development of CuO films for solar windows and other semi-conductor applications including gas sensors.

  15. Laser-induced damage to thin film dielectric coatings

    International Nuclear Information System (INIS)

    Walker, T.W.

    1980-01-01

    The laser-induced damage thresholds of dielectric thin film coatings have been found to be more than an order of magnitude lower than the bulk material damage thresholds. Prior damage studies have been inconclusive in determining the damage mechanism which is operative in thin films. A program was conducted in which thin film damage thresholds were measured as a function of laser wavelength (1.06 μm, 0.53 μm, 0.35 μm and 0.26 μm), laser pulse length (5 and 15 nanoseconds), film materials and film thickness. The large matrix of data was compared to predictions given by avalanche ionization, multiphoton ionization and impurity theories of laser damage. When Mie absorption cross-sections and the exact thermal equations were included into the impurity theory excellent agreement with the data was found. The avalanche and multiphoton damage theories could not account for most parametric variations in the data. For example, the damage thresholds for most films increased as the film thickness decreased and only the impurity theory could account for this behavior. Other observed changes in damage threshold with changes in laser wavelength, pulse length and film material could only be adequately explained by the impurity theory. The conclusion which results from this study is that laser damage in thin film coatings results from absorbing impurities included during the deposition process

  16. Characterization of thin films with synchrotron radiation in SPring-8

    International Nuclear Information System (INIS)

    Komiya, Satoshi

    2005-01-01

    Many studies about thin films by using synchrotron radiation in SPring-8 were reviewed. Structural analyses and assessment of thin films used for electronics, and also assessment of insulating films for the gate used in LSI were carried out. Film thickness, unevenness, and density of SiO 2 films in order of nanomer thickness were determined by interference fringes of x-ray reflection curves. The interface structure of (SiO 2 /Si) films was studied by x-ray crystal truncation rod scattering, and the correlation between leakage character depending on nitrogen concentration and interface structure was clarified on SiON film. The oxygen concentration in HfO films in nanometer thickness was determined by x-ray fluorescence analysis, and the interface reaction for HfO 2 /SiO 2 was clearly observed by electron spectroscopy. The structure of amorphous thin films with large dielectric constant was analyzed by x-ray absorption fine structure (XAFS) spectrum. Devices fabricated from multi-layer films showing giant magnetic resistance were developed for hard disk with a large memory. The character of giant magnetic resistance was governed by multi-layer thin film structure piled up by magnetic and nonmagnetic polycrystalline thin metals. For the multi-layer structure, the concentration distribution of constituent elements was determined to the direction of film thickness by x-ray reflection analysis and grazing incident x-ray fluorescence analysis. In the semiconductor laser source, Ga 1-x In x N, used for DVD, the local structure around In ions was studied by XAFS since constituent instability, especially overpopulation of In element, caused the deterioration of lifetime and light emission of the laser. The lattice constant of the light emission layer in InGaAs was measured by x-ray micro-beams. (author)

  17. Application of HTSC-thin films in microwave bandpass filters

    International Nuclear Information System (INIS)

    Jha, A.R.

    1993-01-01

    This paper reveals unique performance capabilities of High-Temperature Superconducting Thin-Film (HTSCTFs) for possible applications in microwave bandpass filters (BPFs). Microwave filters fabricated with HTSCTFs have demonstrated lowest insertion loss, highest rejection, and sharpest skirt selectivity. Thin films of Yttrium Barium Copper Oxide (YBCO), Bismuth Strontium Calcium Copper Oxide (BSCCO) and Thallium Calcium Barium Copper Oxide (TCBCO) will be most attractive for filters

  18. Liquid phase epitaxial growth of heterostructured hierarchical MOF thin films

    KAUST Repository

    Chernikova, Valeriya; Shekhah, Osama; Spanopoulos, Ioannis; Trikalitis, Pantelis N.; Eddaoudi, Mohamed

    2017-01-01

    Precise control of epitaxial growth of MOF-on-MOF thin films, for ordered hierarchical tbo-type structures is demonstrated. The heterostructured MOF thin film was fabricated by successful sequential deposition of layers from two different MOFs. The 2-periodic layers, edge-transitive 4,4-square lattices regarded as supermolecular building layers, were commendably cross-linked using a combination of inorganic/organic and organic pillars.

  19. Liquid phase epitaxial growth of heterostructured hierarchical MOF thin films

    KAUST Repository

    Chernikova, Valeriya

    2017-05-10

    Precise control of epitaxial growth of MOF-on-MOF thin films, for ordered hierarchical tbo-type structures is demonstrated. The heterostructured MOF thin film was fabricated by successful sequential deposition of layers from two different MOFs. The 2-periodic layers, edge-transitive 4,4-square lattices regarded as supermolecular building layers, were commendably cross-linked using a combination of inorganic/organic and organic pillars.

  20. Simple flash evaporator for making thin films of compounds

    Energy Technology Data Exchange (ETDEWEB)

    Hemanadhan, M.; Bapanayya, Ch.; Agarwal, S. C. [Department of Physics, Indian Institute of Technology, Kanpur 208016 (India)

    2010-07-15

    A simple and compact arrangement for flash evaporation is described. It uses a cell phone vibrator for powder dispensing that can be incorporated into a vacuum deposition chamber without any major alterations. The performance of the flash evaporation system is checked by making thin films of the optical memory chalcogenide glass Ge{sub 2}Sb{sub 2}Te{sub 5} (GST). Energy dispersive x-ray analysis shows that the flash evaporation preserves the stoichiometry in thin films.

  1. Chapter 23. Single and Heterostructure Multiferroic Thin Films

    OpenAIRE

    Barbier , Antoine

    2018-01-01

    International audience; Multiferroic oxide materials exhibiting several long range ferroic orders are of high interest because of their wide range of potential applications. The incorporation of their genuine properties in new devices, offering additional physical properties, requires often elaborating them in form of thin films. Retaining their multiferroic characteristics is very challenging. However, thin films can be structured on the nanometer scale and additional degrees of freedom, suc...

  2. Deposition and characterisation of epitaxial oxide thin films for SOFCs

    KAUST Repository

    Santiso, José

    2010-10-24

    This paper reviews the recent advances in the use of thin films, mostly epitaxial, for fundamental studies of materials for solid oxide fuel cell (SOFC) applications. These studies include the influence of film microstructure, crystal orientation and strain in oxide ionic conducting materials used as electrolytes, such as fluorites, and in mixed ionic and electronic conducting materials used as electrodes, typically oxides with perovskite or perovskite-related layered structures. The recent effort towards the enhancement of the electrochemical performance of SOFC materials through the deposition of artificial film heterostructures is also presented. These thin films have been engineered at a nanoscale level, such as the case of epitaxial multilayers or nanocomposite cermet materials. The recent progress in the implementation of thin films in SOFC devices is also reported. © 2010 Springer-Verlag.

  3. Multiferroicity in oxide thin films and heterostructures

    International Nuclear Information System (INIS)

    Glavic, Artur

    2012-01-01

    In this work a variety of different systems of transition metal oxides ABO 3 (perovskite materials, where B stands for a transition metal and A for a rare earth element) were produced as thin films and heterostructures and analyzed for the structural, magnetic and ferroelectric properties. For the epitaxial film preparation mostly pulse laser deposition (PLD) was applied. For one series high pressure oxide sputter deposition was used as well. The bulk multiferroics TbMnO 3 and DyMnO 3 , which develop their electric polarization due to a cycloidal magnetic order, have been prepared as single layers with thicknesses between 2 and 200 nm on YAlO 3 substrates using PLD and sputter deposition. The structural characterization of the surfaces and crystal structure where performed using X-ray reflectometry and diffraction, respectively. These yielded low surface roughness and good epitaxial growth. The magnetic behavior was macroscopically measured with SQUID magnetometry and microscopically with polarized neutron diffraction and resonant magnetic X-ray scattering. While all investigated samples showed antiferromagnetic order, comparable with the collinear magnetic phase of their bulk materials, only the sputter deposited samples exhibited the multiferroic low temperature cycloidal order. The investigation of the optical second harmonic generation in a TbMnO 3 sample could proof the presence of a ferroelectric order in the low temperature phase. The respective transition temperatures of the thin films have been very similar to those of the bulk materials. In contrast an increase in the rare earth ordering temperature has been observed, which reduces the Mn order slightly, an effect not known from bulk TbMnO 3 crystals. The coupling of the antiferromagnetic order in TbMnO 3 to ferromagnetic layers of LaCoO 3 was investigated in super-lattices containing 20 bilayers produced with PLD on the same substrates. The SQUID magnetometry yielded a strong influence of the

  4. Superior Properties of Energetically Stable La2/3Sr1/3MnO3/Tetragonal BiFeO3 Multiferroic Superlattices

    KAUST Repository

    Feng, Nan; Mi, Wenbo; Wang, Xiaocha; Cheng, Yingchun; Schwingenschlö gl, Udo

    2015-01-01

    The superlattice of energetically stable La2/3Sr1/3MnO3 and tetragonal BiFeO3 is investigated by means of density functional theory. The superlattice as a whole exhibits a half-metallic character, as is desired for spintronic devices. The interfacial electronic states and exchange coupling are analyzed in details. We demonstrate that the interfacial O atoms play a key role in controlling the coupling. The higher ferroelectricity of tetragonal BiFeO3 and stronger response to the magnetic moment in La2/3Sr1/3MnO3/BiFeO3 superlattice show a strongly enhanced electric control of the magnetism as compared to the rhombohedral one. Therefore, it is particularly practical interest in the magnetoelectric controlled spintronic devices.

  5. Superior Properties of Energetically Stable La2/3Sr1/3MnO3/Tetragonal BiFeO3 Multiferroic Superlattices

    KAUST Repository

    Feng, Nan

    2015-04-30

    The superlattice of energetically stable La2/3Sr1/3MnO3 and tetragonal BiFeO3 is investigated by means of density functional theory. The superlattice as a whole exhibits a half-metallic character, as is desired for spintronic devices. The interfacial electronic states and exchange coupling are analyzed in details. We demonstrate that the interfacial O atoms play a key role in controlling the coupling. The higher ferroelectricity of tetragonal BiFeO3 and stronger response to the magnetic moment in La2/3Sr1/3MnO3/BiFeO3 superlattice show a strongly enhanced electric control of the magnetism as compared to the rhombohedral one. Therefore, it is particularly practical interest in the magnetoelectric controlled spintronic devices.

  6. Thin films as an emerging platform for drug delivery

    Directory of Open Access Journals (Sweden)

    Sandeep Karki

    2016-10-01

    Full Text Available Pharmaceutical scientists throughout the world are trying to explore thin films as a novel drug delivery tool. Thin films have been identified as an alternative approach to conventional dosage forms. The thin films are considered to be convenient to swallow, self-administrable, and fast dissolving dosage form, all of which make it as a versatile platform for drug delivery. This delivery system has been used for both systemic and local action via several routes such as oral, buccal, sublingual, ocular, and transdermal routes. The design of efficient thin films requires a comprehensive knowledge of the pharmacological and pharmaceutical properties of drugs and polymers along with an appropriate selection of manufacturing processes. Therefore, the aim of this review is to provide an overview of the critical factors affecting the formulation of thin films, including the physico-chemical properties of polymers and drugs, anatomical and physiological constraints, as well as the characterization methods and quality specifications to circumvent the difficulties associated with formulation design. It also highlights the recent trends and perspectives to develop thin film products by various companies.

  7. The optical properties of plasma polymerized polyaniline thin films

    Energy Technology Data Exchange (ETDEWEB)

    Goktas, Hilal, E-mail: hilal_goktas@yahoo.com [Canakkale Onsekiz Mart University, Physics Department, 17020 Canakkale (Turkey); Demircioglu, Zahide; Sel, Kivanc [Canakkale Onsekiz Mart University, Physics Department, 17020 Canakkale (Turkey); Gunes, Taylan [Yalova University, Energy Systems Engineering Department, 77100 Yalova (Turkey); Kaya, Ismet [Canakkale Onsekiz Mart University, Chemistry Department, 17020 Canakkale (Turkey)

    2013-12-02

    We report herein the characterizations of polyaniline thin films synthesized using double discharge plasma system. Quartz glass substrates were coated at a pressure of 80 Pa, 19.0 kV pulsed and 1.5 kV dc potential. The substrates were located at different regions in the reactor to evaluate the influence of the position on the morphological and molecular structure of the obtained thin films. The molecular structure of the thin films was investigated by Fourier transform infrared (FTIR) and UV–visible photospectrometers (UV–vis), and the morphological studies were carried out by scanning electron microscope. The FTIR and UV–vis data revealed that the molecular structures of the synthesized thin films were in the form of leuocoemeraldine and exhibited similar structures with the films produced via chemical or electrochemical methods. The optical energy band gap values of the as-grown samples ranged from 2.5 to 3.1 eV, which indicated that these materials have potential applications in semiconductor devices. The refractive index in the transparent region (from 650 to 1000 nm) steadily decreased from 1.9 to 1.4 and the extinction coefficient was found to be on order of 10{sup −4}. The synthesized thin films showed various degrees of granular morphologies depending on the location of the substrate in the reactor. - Highlights: • Polyaniline thin films were synthesized for the first time via double discharge plasma system. • The films have similar structure to that of the chemically synthesized films. • The morphology of the films could be tuned by this technique. • These materials would have potential applications at semiconductor devices.

  8. Emergent Topological Phenomena in Thin Films of Pyrochlore Iridates

    Science.gov (United States)

    Yang, Bohm-Jung; Nagaosa, Naoto

    2014-06-01

    Because of the recent development of thin film and artificial superstructure growth techniques, it is possible to control the dimensionality of the system, smoothly between two and three dimensions. In this Letter we unveil the dimensional crossover of emergent topological phenomena in correlated topological materials. In particular, by focusing on the thin film of pyrochlore iridate antiferromagnets grown along the [111] direction, we demonstrate that the thin film can have a giant anomalous Hall conductance, proportional to the thickness of the film, even though there is no Hall effect in 3D bulk material. Moreover, in the case of ultrathin films, a quantized anomalous Hall conductance can be observed, despite the fact that the system is an antiferromagnet. In addition, we uncover the emergence of a new topological phase, the nontrivial topological properties of which are hidden in the bulk insulator and manifest only in thin films. This shows that the thin film of correlated topological materials is a new platform to search for unexplored novel topological phenomena.

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

    KAUST Repository

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

    2010-01-01

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

  10. Geometric shape control of thin film ferroelectrics and resulting structures

    Science.gov (United States)

    McKee, Rodney A.; Walker, Frederick J.

    2000-01-01

    A monolithic crystalline structure and a method of making involves a semiconductor substrate, such as silicon, and a ferroelectric film, such as BaTiO.sub.3, overlying the surface of the substrate wherein the atomic layers of the ferroelectric film directly overlie the surface of the substrate. By controlling the geometry of the ferroelectric thin film, either during build-up of the thin film or through appropriate treatment of the thin film adjacent the boundary thereof, the in-plane tensile strain within the ferroelectric film is relieved to the extent necessary to permit the ferroelectric film to be poled out-of-plane, thereby effecting in-plane switching of the polarization of the underlying substrate material. The method of the invention includes the steps involved in effecting a discontinuity of the mechanical restraint at the boundary of the ferroelectric film atop the semiconductor substrate by, for example, either removing material from a ferroelectric film which has already been built upon the substrate, building up a ferroelectric film upon the substrate in a mesa-shaped geometry or inducing the discontinuity at the boundary by ion beam deposition techniques.

  11. Characterisation and optical vapour sensing properties of PMMA thin films

    Energy Technology Data Exchange (ETDEWEB)

    Capan, I. [Balikesir University, Science and Arts Faculty, Physics Department, 10100 Balikesir (Turkey)], E-mail: inci.capan@gmail.com; Tarimci, C. [Ankara University, Faculty of Engineering, Department of Engineering Physics, 06100, Tandogan, Ankara (Turkey); Hassan, A.K. [Sheffield Hallam University, Materials and Engineering Research Institute, City Campus, Pond Street, Sheffield S1 1WB (United Kingdom); Tanrisever, T. [Balikesir University, Science and Arts Faculty, Chemistry Department, 10100 Balikesir (Turkey)

    2009-01-01

    The present article reports on the characterisation of spin coated thin films of poly (methyl methacrylate) (PMMA) for their use in organic vapour sensing application. Thin film properties of PMMA are studied by UV-visible spectroscopy, atomic force microscopy and surface plasmon resonance (SPR) technique. Results obtained show that homogeneous thin films with thickness in the range between 6 and 15 nm have been successfully prepared when films were spun at speeds between 1000-5000 rpm. Using SPR technique, the sensing properties of the spun films were studied on exposures to several halohydrocarbons including chloroform, dichloromethane and trichloroethylene. Data from measured kinetic response have been used to evaluate the sensitivity of the studied films to the various analyte molecules in terms of normalised response (%) per unit concentration (ppm). The highest PMMA film sensitivity of 0.067 normalised response per ppm was observed for chloroform vapour, for films spun at 1000 rpm. The high film's sensitivity to chloroform vapour was ascribed mainly to its solubility parameter and molar volume values. Effect of film thickness on the vapour sensing properties is also discussed.

  12. Magnetoelectric effect in (BiFeO3x–(BaTiO31-x solid solutions

    Directory of Open Access Journals (Sweden)

    Kowal Karol

    2015-03-01

    Full Text Available The aim of the present work was to study magnetoelectric effect (ME in (BiFeO3x-(BaTiO31-x solid solutions in terms of technological conditions applied in the samples fabrication process. The rapidly growing interest in these materials is caused by their multiferroic behaviour, i.e. coexistence of both electric and magnetic ordering. It creates possibility for many innovative applications, e.g. in steering the magnetic memory by electric field and vice versa. The investigated samples of various chemical compositions (i.e. x = 0.7, 0.8 and 0.9 were prepared by the solid-state sintering method under three sets of technological conditions differing in the applied temperature and soaking time. Measurements of the magnetoelectric voltage coefficient αME were performed using a dynamic lock-in technique. The highest value of αME was observed for 0.7BiFeO3-0.3BaTiO3 solid solution sintered at the highest temperature (T = 1153 K after initial electrical poling despite that the soaking time was reduced 10 times in this case.

  13. Effects of (La, Sr) co-doping on electrical conduction and magnetic properties of BiFeO3 nanoparticles

    International Nuclear Information System (INIS)

    Liu Li; Wang Shouyu; Yin Zi; Zhang Chuang; Li Xiu; Yang Jiabin; Liu Weifang; Xu Xunling

    2016-01-01

    Multiferroic material as a photovoltaic material has gained considerable attention in recent years. Nanoparticles (NPs) La 0.1 Bi 0.9−x Sr x FeO y (LBSF, x = 0, 0.2, 0.4) with dopant Sr 2+ ions were synthesized by the sol–gel method. A systematic change in the crystal structure from rhombohedral to tetragonal upon increasing Sr doping was observed. There is an obvious change in the particle size from 180 nm to 50 nm with increasing Sr substitution into LBFO. It was found that Sr doping effectively narrows the band gap from ∼ 2.08 eV to ∼ 1.94 eV, while it leads to an apparent enhancement in the electrical conductivity of LBSF NPs, making a transition from insulator to semiconductor. This suggests an effective way to modulate the conductivity of BiFeO 3 -based multiferroic materials with pure phase by co-doping with La and Sr at the A sites of BiFeO 3 . (paper)

  14. Structural, magnetic and electric properties of Nd and Ni co-doped BiFeO3 materials

    Directory of Open Access Journals (Sweden)

    Dao Viet Thang

    2017-09-01

    Full Text Available Multiferroic Bi1−xNdxFe0.975Ni0.025O3 (x = 0.00, 0.05, 0.10, 0.125, and 0.15 (BNFNO and BiFeO3 (BFO materials were synthesized by a sol-gel method. Crystal structure, ferromagnetic and ferroelectric properties of the as-synthesized materials were investigated. Results showed that Nd3+ and Ni2+ co-doping affected to the electrical leakage, enhanced ferroelectric polarization and magnetization of BiFeO3. Co-doped sample with 12.5 mol% of Nd3+ and 2.5 mol% of Ni2+ exhibited an enhancement in both ferromagnetism and ferroelectric properties up to MS ~ 0.528 emu/g and PS ~ 18.35 μC/cm2 with applied electric field at 5 kV/cm, respectively. The origins of ferromagnetism and ferroelectricity enhancement were discussed in the paper.

  15. Phase pure synthesis of BiFeO3 nanopowders using diverse precursor via co-precipitation method

    International Nuclear Information System (INIS)

    Shami, M. Yasin; Awan, M.S.; Anis-ur-Rehman, M.

    2011-01-01

    Highlights: → Synthesized phase pure BiFeO 3 using diverse precursor by co-precipitation method. → Optimized synthesis and processing parameters. → Thermal behavior, structure and microstructure were analyzed. → Resistivity vs temperature and dielectric constant vs frequency were measured. → Multiferroicity at room temperature was confirmed by M-H and P-E loops. - Abstract: Amorphous powder of BiFeO 3 (BFO) was synthesized at low-temperature (80 deg. C) by co-precipitation method. Optimal synthesis conditions for phase pure BFO were obtained. Powders were calcined in the temperature range from 400 to 600 deg. C for 1 h. Iso-statically pressed powder was sintered at 500 deg. C for 2 h. Differential scanning calorimetric thermo-gram guided for phase transition, crystallization and melting temperatures. X-ray diffraction confirmed the amorphous nature of as synthesized powder and phase formation of calcined powders. Calcination at temperature ≥400 deg. C resulted in nano crystalline powders with perovskite structure. Average crystallite size increased with the increase in calcination temperature. Scanning electron microscopic studies revealed dense granular microstructure of the sintered samples. The sintered samples exhibited high dc resistivity at room temperature which decreased with the increase in temperature. Dielectric constant, dielectric loss tangent and ac conductivity measurements were carried out in the frequency range (10 Hz to 2 MHz). The samples responded weak electric and magnetic polarization at room temperature with unsaturated and hysteresis free loops, respectively.

  16. Thin films of metal-organic compounds and metal nanoparticle ...

    Indian Academy of Sciences (India)

    Optical limiting capability of the nanoparticle-embedded polymer film is demonstrated. Keywords. Polar crystal; uniaxial orientational order; thin film; second harmonic gen- eration; silver ... able content of metal nanoparticles would be of considerable value from an appli- ... polar chain and perpendicular to it [10].

  17. Magnetic hysteresis measurements of thin films under isotropic stress.

    Science.gov (United States)

    Holland, Patrick; Dubey, Archana; Geerts, Wilhelmus

    2000-10-01

    Nowadays, ferromagnetic thin films are widely applied in devices for information technology (credit cards, video recorder tapes, floppies, hard disks) and sensors (air bags, anti-breaking systems, navigation systems). Thus, with the increase in the use of magnetic media continued investigation of magnetic properties of materials is necessary to help in determining the useful properties of materials for new or improved applications. We are currently interested in studying the effect of applied external stress on Kerr hysteresis curves of thin magnetic films. The Ni and NiFe films were grown using DC magnetron sputtering with Ar as the sputter gas (pAr=4 mTorr; Tsub=55-190 C). Seed and cap layers of Ti were used on all films for adhesion and oxidation protection, respectively. A brass membrane pressure cell was designed to apply in-plane isotropic stress to thin films. In this pressure cell, gas pressure is used to deform a flexible substrate onto which a thin magnetic film has been sputtered. The curvature of the samples could be controlled by changing the gas pressure to the cell. Magneto-Optical in-plane hysteresis curves at different values of strain were measured. The results obtained show that the stress sensitivity is dependent on the film thickness. For the 500nm NiFe films, the coercivity strongly decreased as a function of the applied stress.

  18. Preparation of self-supporting thin metal target films

    International Nuclear Information System (INIS)

    Wang Xiuying; Ge Suxian; Yin Jianhua; Yin Xu; Jin Genming

    1989-01-01

    The preparation method and equipment for thin metal self-supporting target without oil contamination are described. The influence of target films contaminated by oil vapor on accuracy of nuclear-physics experimental data are also discussed. The analytical results on carbon content in the prepared films of three elements show that the equipment is very effective for eliminating contamination

  19. Ellipsometric investigations of pyrolytically deposited thin indium oxide films

    International Nuclear Information System (INIS)

    Winkler, U.

    1980-01-01

    Ellipsometric measurements have been carried out of thin indium oxide films deposited pyrolytically on glass substrates. It was found that the roughness of the films affected the measuring results. Therefore, only after applying a two-layer model a reasonable interpretation of the measuring results became possible

  20. Determination of magnetic properties of multilayer metallic thin films

    International Nuclear Information System (INIS)

    Birlikseven, C.

    2000-01-01

    In recent year, Giant Magnetoresistance Effect has been attracting an increasingly high interest. High sensitivity magnetic field detectors and high sensitivity read heads of magnetic media can be named as important applications of these films. In this work, magnetic and electrical properties of single layer and thin films were investigated. Multilayer thin films were supplied by Prof. Dr. A. Riza Koeymen from Texas University. Multilayer magnetic thin films are used especially for magnetic reading and magnetic writing. storing of large amount of information into small areas become possible with this technology. Single layer films were prepared using the electron beam evaporation technique. For the exact determination of film thicknesses, a careful calibration of the thicknesses was made. Magnetic properties of the multilayer films were studied using the magnetization, magnetoresistance measurements and ferromagnetic resonance technique. Besides, by fitting the experimental results to the theoretical models, effective magnetization and angles between the ferromagnetic layers were calculated. The correspondence between magnetization and magnetoresistance was evaluated. To see the effect of anisotropic magnetoresistance in the magnetoresistance measurements, a new experimental set-up was build and measurements were taken in this set-up. A series of soft permalloy thin films were made, and temperature dependent resistivity, magnetoresistance, anisotropic magnetoresistance and magnetization measurements were taken