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Sample records for oxide film obta

  1. Stabilized chromium oxide film

    DOEpatents

    Garwin, Edward L.; Nyaiesh, Ali R.

    1988-01-01

    Stabilized air-oxidized chromium films deposited on high-power klystron ceramic windows and sleeves having a thickness between 20 and 150.ANG. are useful in lowering secondary electron emission yield and in avoiding multipactoring and window failure due to overheating. The ceramic substrate for the film is chosen from alumina, sapphire or beryllium oxide.

  2. Stabilized chromium oxide film

    DOEpatents

    Nyaiesh, A.R.; Garwin, E.L.

    1986-08-04

    Stabilized air-oxidized chromium films deposited on high-power klystron ceramic windows and sleeves having a thickness between 20 and 150A are useful in lowering secondary electron emission yield and in avoiding multipactoring and window failure due to overheating. The ceramic substrate for the film is chosen from alumina, sapphire or beryllium oxide.

  3. Oxide Films RF Applications

    DTIC Science & Technology

    2006-06-01

    AUTHOR(S) 5d. PROJECT NUMBER SKOWRONSKI , Marek 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING...Report Title: Oxide Films RF applications University: Carnegie Mellon University PIs: M. Skowronski & P. Salvador Agency: Office of Naval Research Award

  4. Metal oxide films on metal

    DOEpatents

    Wu, Xin D.; Tiwari, Prabhat

    1995-01-01

    A structure including a thin film of a conductive alkaline earth metal oxide selected from the group consisting of strontium ruthenium trioxide, calcium ruthenium trioxide, barium ruthenium trioxide, lanthanum-strontium cobalt oxide or mixed alkaline earth ruthenium trioxides thereof upon a thin film of a noble metal such as platinum is provided.

  5. Oxide Films for RF Applications

    DTIC Science & Technology

    2008-07-01

    structured thin film superlattices of (AEO)m( TiO2 )n - type with varying m and n numbers in order to generate a homologous series of materials having...mechanisms in MBE oxide films The proposed goal was to identify, isolate, and reduce sources of loss in thin film dielectrics. It is important to note...that the loss in bulk single crystals is often orders of magnitude below that of their thin film counterparts. It is believed that defects in thin

  6. Process for fabrication of metal oxide films

    SciTech Connect

    Tracy, C.E.; Benson, D.; Svensson, S.

    1990-07-17

    This invention is comprised of a method of fabricating metal oxide films from a plurality of reactants by inducing a reaction by plasma deposition among the reactants. The plasma reaction is effective for consolidating the reactants and producing thin films of metal oxides, e.g. electro-optically active transition metal oxides, at a high deposition rate. The presence of hydrogen during the plasma reaction enhances the deposition rate of the metal oxide. Various types of metal oxide films can be produced.

  7. Thin film hydrous metal oxide catalysts

    DOEpatents

    Dosch, Robert G.; Stephens, Howard P.

    1995-01-01

    Thin film (<100 nm) hydrous metal oxide catalysts are prepared by 1) synthesis of a hydrous metal oxide, 2) deposition of the hydrous metal oxide upon an inert support surface, 3) ion exchange with catalytically active metals, and 4) activating the hydrous metal oxide catalysts.

  8. Electrochromism in copper oxide thin films

    SciTech Connect

    Richardson, T.J.; Slack, J.L.; Rubin, M.D.

    2000-08-15

    Transparent thin films of copper(I) oxide prepared on conductive SnO2:F glass substrates by anodic oxidation of sputtered copper films or by direct electrodeposition of Cu2O transformed reversibly to opaque metallic copper films when reduced in alkaline electrolyte. In addition, the same Cu2O films transform reversibly to black copper(II) oxide when cycled at more anodic potentials. Copper oxide-to-copper switching covered a large dynamic range, from 85% and 10% photopic transmittance, with a coloration efficiency of about 32 cm2/C. Gradual deterioration of the switching range occurred over 20 to 100 cycles. This is tentatively ascribed to coarsening of the film and contact degradation caused by the 65% volume change on conversion of Cu to Cu2O. Switching between the two copper oxides (which have similar volumes) was more stable and more efficient (CE = 60 cm2/C), but covered a smaller transmittance range (60% to 44% T). Due to their large electrochemical storage capacity and tolerance for alkaline electrolytes, these cathodically coloring films may be useful as counter electrodes for anodically coloring electrode films such as nickel oxide or metal hydrides.

  9. High quality oxide films on substrates

    DOEpatents

    Ruckman, Mark W.; Strongin, Myron; Gao, Yong L.

    1994-01-01

    A method for providing an oxide film of a material on the surface of a substrate using a reactive deposition of the material onto the substrate surface in the presence of a solid or liquid layer of an oxidizing gas. The oxidizing gas is provided on the substrate surface in an amount sufficient to dissipate the latent heat of condensation occurring during deposition as well as creating a favorable oxidizing environment for the material.

  10. High quality oxide films on substrates

    DOEpatents

    Ruckman, M.W.; Strongin, M.; Gao, Y.L.

    1994-02-01

    A method is described for providing an oxide film of a material on the surface of a substrate using a reactive deposition of the material onto the substrate surface in the presence of a solid or liquid layer of an oxidizing gas. The oxidizing gas is provided on the substrate surface in an amount sufficient to dissipate the latent heat of condensation occurring during deposition as well as creating a favorable oxidizing environment for the material. 4 figures.

  11. Electro-deposition of superconductor oxide films

    DOEpatents

    Bhattacharya, Raghu N.

    2001-01-01

    Methods for preparing high quality superconducting oxide precursors which are well suited for further oxidation and annealing to form superconducting oxide films. The method comprises forming a multilayered superconducting precursor on a substrate by providing an electrodeposition bath comprising an electrolyte medium and a substrate electrode, and providing to the bath a plurality of precursor metal salts which are capable of exhibiting superconducting properties upon subsequent treatment. The superconducting precursor is then formed by electrodepositing a first electrodeposited (ED) layer onto the substrate electrode, followed by depositing a layer of silver onto the first electrodeposited (ED) layer, and then electrodepositing a second electrodeposited (ED) layer onto the Ag layer. The multilayered superconducting precursor is suitable for oxidation at a sufficient annealing temperature in air or an oxygen-containing atmosphere to form a crystalline superconducting oxide film.

  12. Investigation of electrodeposited cuprous oxide thin films

    NASA Astrophysics Data System (ADS)

    Mortensen, Emma L.

    This dissertation focuses on improvements to electrodeposited cuprous oxide as a candidate for the absorber layer for a thin film solar cell that could be integrated into a mechanical solar cell stack. Cuprous oxide (Cu2O) is an earth abundant material that has a bandgap of 2 eV with absorption coefficients around 102-106 cm-1. This bandgap is not optimized for use as a single-junction solar cell, but could be ideal for use in a tandem solar cell device. The theoretical efficiency of a material with a bandgap of 2.0 eV is 20%. The greatest actual efficiency that has been achieved for a Cu2O solar cell is only 8.1%. For the present work the primary focus has been on improving the microstructure of the absorber layer film. The Cu2O films were fabricated using electrodeposition. A seeding layer was developed using gold (Au); which was manipulated into nano-islands and used as the substrate for the Cu2O electrodeposition. The films were characterized and compared to determine the growth mechanism of each film using scanning electron microscopy (SEM). X-ray diffraction (XRD) was used to establish and compare the chemical phases that were present in each of the films. The crystal structure of the Cu2O film grown on gold was explored using transmission electron microscopy (TEM), and this helped confirm the effect that the gold had on the growth of Cu2O. The Tauc method was then used to determine the bandgap of the films of Cu2O grown on both substrates and this showed that the Au based Cu2O film was a superior film. Electrical tests were also completed using a solar simulator and this established that the film grown on gold exhibited photoconductivity that was not seen on the film without gold. In addition, for this thesis, a method for depositing an n-type Cu2O film, based on a Cu-metal solution-boiling process, was investigated. Three forms of copper were tested: a sheet of copper, electrodeposited copper, and sputtered copper. The chemical phases were observed using

  13. Sprayed lanthanum doped zinc oxide thin films

    NASA Astrophysics Data System (ADS)

    Bouznit, Y.; Beggah, Y.; Ynineb, F.

    2012-01-01

    Lanthanum doped zinc oxide thin films were deposited on soda-lime glass substrates using a pneumatic spray pyrolysis technique. The films were prepared using different lanthanum concentrations at optimum deposition parameters. We studied the variations in structural, morphological and optical properties of the samples due to the change of doping concentration in precursor solutions. X-ray diffraction (XRD) patterns show that pure and La-doped ZnO thin films are highly textured along c-axis perpendicular to the surface of the substrate. Scanning electron micrographs show that surface morphology of ZnO films undergoes a significant change according to lanthanum doping. All films exhibit a transmittance higher than 80% in the visible region.

  14. Graphene oxide film as solid lubricant.

    PubMed

    Liang, Hongyu; Bu, Yongfeng; Zhang, Junyan; Cao, Zhongyue; Liang, Aimin

    2013-07-10

    As a layered material, graphene oxide (GO) film is a good candidate for improving friction and antiwear performance of silicon-based MEMS devices. Via a green electrophoretic deposition (EPD) approach, GO films with tunable thickness in nanoscale are fabricated onto silicon wafer in a water solution. The morphology, microstructure, and mechanical properties as well as the friction coefficient and wear resistance of the films were investigated. The results indicated that the friction coefficient of silicon wafer was reduced to 1/6 its value, and the wear volume was reduced to 1/24 when using GO film as solid lubricant. These distinguished tribology performances suggest that GO films are expected to be good solid lubricants for silicon-based MEMS/NEMS devices.

  15. Transferable graphene oxide films with tunable microstructures.

    PubMed

    Hasan, Saad A; Rigueur, John L; Harl, Robert R; Krejci, Alex J; Gonzalo-Juan, Isabel; Rogers, Bridget R; Dickerson, James H

    2010-12-28

    This report describes methods to produce large-area films of graphene oxide from aqueous suspensions using electrophoretic deposition. By selecting the appropriate suspension pH and deposition voltage, films of the negatively charged graphene oxide sheets can be produced with either a smooth "rug" microstructure on the anode or a porous "brick" microstructure on the cathode. Cathodic deposition occurs in the low pH suspension with the application of a relatively high voltage, which facilitates a gradual change in the colloids' charge from negative to positive as they adsorb protons released by the electrolysis of water. The shift in the colloids' charge also gives rise to the brick microstructure, as the concurrent decrease in electrostatic repulsion between graphene oxide sheets results in the formation of multilayered aggregates (the "bricks"). Measurements of water contact angle revealed the brick films (79°) to be more hydrophobic than the rug films (41°), a difference we attribute primarily to the distinct microstructures. Finally, we describe a sacrificial layer technique to make these graphene oxide films free-standing, which would enable them to be placed on arbitrary substrates.

  16. High quality transparent conducting oxide thin films

    DOEpatents

    Gessert, Timothy A.; Duenow, Joel N.; Barnes, Teresa; Coutts, Timothy J.

    2012-08-28

    A transparent conducting oxide (TCO) film comprising: a TCO layer, and dopants selected from the elements consisting of Vanadium, Molybdenum, Tantalum, Niobium, Antimony, Titanium, Zirconium, and Hafnium, wherein the elements are n-type dopants; and wherein the transparent conducting oxide is characterized by an improved electron mobility of about 42 cm.sup.2/V-sec while simultaneously maintaining a high carrier density of .about.4.4e.times.10.sup.20 cm.sup.-3.

  17. Patterning of Indium Tin Oxide Films

    NASA Technical Reports Server (NTRS)

    Immer, Christopher

    2008-01-01

    A relatively rapid, economical process has been devised for patterning a thin film of indium tin oxide (ITO) that has been deposited on a polyester film. ITO is a transparent, electrically conductive substance made from a mixture of indium oxide and tin oxide that is commonly used in touch panels, liquid-crystal and plasma display devices, gas sensors, and solar photovoltaic panels. In a typical application, the ITO film must be patterned to form electrodes, current collectors, and the like. Heretofore it has been common practice to pattern an ITO film by means of either a laser ablation process or a photolithography/etching process. The laser ablation process includes the use of expensive equipment to precisely position and focus a laser. The photolithography/etching process is time-consuming. The present process is a variant of the direct toner process an inexpensive but often highly effective process for patterning conductors for printed circuits. Relative to a conventional photolithography/ etching process, this process is simpler, takes less time, and is less expensive. This process involves equipment that costs less than $500 (at 2005 prices) and enables patterning of an ITO film in a process time of less than about a half hour.

  18. Aluminum oxide film thickness and emittance

    SciTech Connect

    Thomas, J.K.; Ondrejcin, R.S.

    1991-11-01

    Aluminum reactor components which are not actively cooled could be subjected to high temperatures due to gamma heating after the core coolant level dropped during the ECS phase of a hypothetical LOCA event. Radiative heat transfer is the dominant heat transfer process in this scenario and therefore the emittance of these components is of interest. Of particular interest are the safety rod thimbles and Mark 60B blanket assemblies; for the K Reactor, these components have been exposed to low temperature (< 55{degrees}C) moderator for about a year. The average moderator temperature was assumed to be 30{degrees}C. The Al oxide film thickness at this temperature, after one year of exposure, is predicted to be 6.4 {mu}m {plus minus} 10%; insensitive to exposure time. Dehydration of the film during the gamma heating accident would result in a film thickness of 6.0 {mu}m {plus minus} 11%. Total hemispherical emittance is predicted to be 0.69 at 96{degrees}C, decreasing to 0.45 at 600{degrees}C. Some phenomena which would tend to yield thicker oxide films in the reactor environment relative to those obtained under experimental conditions were neglected and the predicted film thickness values are therefore conservative. The emittance values predicted for a given film thickness are also conservative. The conservativisms inherent in the predicted emittance are particularly relevant for uncertainty analysis of temperatures generated using these values.

  19. Aluminum oxide film thickness and emittance

    SciTech Connect

    Thomas, J.K.; Ondrejcin, R.S.

    1991-11-01

    Aluminum reactor components which are not actively cooled could be subjected to high temperatures due to gamma heating after the core coolant level dropped during the ECS phase of a hypothetical LOCA event. Radiative heat transfer is the dominant heat transfer process in this scenario and therefore the emittance of these components is of interest. Of particular interest are the safety rod thimbles and Mark 60B blanket assemblies; for the K Reactor, these components have been exposed to low temperature (< 55{degrees}C) moderator for about a year. The average moderator temperature was assumed to be 30{degrees}C. The Al oxide film thickness at this temperature, after one year of exposure, is predicted to be 6.4 {mu}m {plus_minus} 10%; insensitive to exposure time. Dehydration of the film during the gamma heating accident would result in a film thickness of 6.0 {mu}m {plus_minus} 11%. Total hemispherical emittance is predicted to be 0.69 at 96{degrees}C, decreasing to 0.45 at 600{degrees}C. Some phenomena which would tend to yield thicker oxide films in the reactor environment relative to those obtained under experimental conditions were neglected and the predicted film thickness values are therefore conservative. The emittance values predicted for a given film thickness are also conservative. The conservativisms inherent in the predicted emittance are particularly relevant for uncertainty analysis of temperatures generated using these values.

  20. Metal current collect protected by oxide film

    DOEpatents

    Jacobson, Craig P.; Visco, Steven J.; DeJonghe, Lutgard C.

    2004-05-25

    Provided are low-cost, mechanically strong, highly electronically conductive current collects and associated structures for solid-state electrochemical devices, techniques for forming these structures, and devices incorporating the structures. The invention provides solid state electrochemical devices having as current interconnects a ferritic steel felt or screen coated with a protective oxide film.

  1. Thin-Film Solid Oxide Fuel Cells

    NASA Technical Reports Server (NTRS)

    Chen, Xin; Wu, Nai-Juan; Ignatiev, Alex

    2009-01-01

    The development of thin-film solid oxide fuel cells (TFSOFCs) and a method of fabricating them have progressed to the prototype stage. This can result in the reduction of mass, volume, and the cost of materials for a given power level.

  2. Ferromagnetism of zinc oxide nanograined films

    NASA Astrophysics Data System (ADS)

    Straumal, B. B.; Protasova, S. G.; Mazilkin, A. A.; Schütz, G.; Goering, E.; Baretzky, B.; Straumal, P. B.

    2013-05-01

    The reasons for the appearance of ferromagnetic properties of zinc oxide have been reviewed. It has been shown that ferromagnetism appears only in polycrystals at a quite high density of grain boundaries. The critical size of grains is about 20 nm for pure ZnO and more than 40 μm for iron-doped zinc oxide. The solubility of manganese and cobalt in zinc oxide increases significantly with a decrease in the size of grains. The dependences of the saturation magnetization on the concentrations of cobalt, manganese, and ion are nonmonotonic. Even if the size of grains is below the critical value, the ferromagnetic properties of zinc oxide depend significantly on the texture of films and the structure of amorphous intercrystallite layers.

  3. Porous Nickel Oxide Film Sensor for Formaldehyde

    NASA Astrophysics Data System (ADS)

    Cindemir, U.; Topalian, Z.; Österlund, L.; Granqvist, C. G.; Niklasson, G. A.

    2014-11-01

    Formaldehyde is a volatile organic compound and a harmful indoor pollutant contributing to the "sick building syndrome". We used advanced gas deposition to fabricate highly porous nickel oxide (NiO) thin films for formaldehyde sensing. The films were deposited on Al2O3 substrates with prefabricated comb-structured electrodes and a resistive heater at the opposite face. The morphology and structure of the films were investigated with scanning electron microscopy and X-ray diffraction. Porosity was determined by nitrogen adsorption isotherms with the Brunauer-Emmett-Teller method. Gas sensing measurements were performed to demonstrate the resistive response of the sensors with respect to different concentrations of formaldehyde at 150 °C.

  4. Metallic oxide switches using thick film technology

    NASA Technical Reports Server (NTRS)

    Patel, D. N.; Williams, L., Jr.

    1974-01-01

    Metallic oxide thick film switches were processed on alumina substrates using thick film technology. Vanadium pentoxide in powder form was mixed with other oxides e.g., barium, strontium copper and glass frit, ground to a fine powder. Pastes and screen printable inks were made using commercial conductive vehicles and appropriate thinners. Some switching devices were processed by conventional screen printing and firing of the inks and commercial cermet conductor terminals on 96% alumina substrates while others were made by applying small beads or dots of the pastes between platinum wires. Static, and dynamic volt-ampere, and pulse tests indicate that the switching and self-oscillatory characteristics of these devices could make them useful in memory element, oscillator, and automatic control applications.

  5. Silicon oxide colloidal/polymer nanocomposite films

    SciTech Connect

    Wang Haifeng; Cao Wenwu; Zhou, Q.F.; Shung, K. Kirk; Huang, Y.H.

    2004-12-13

    The quarter-wavelength ({lambda}/4) acoustic matching layer, a vital component in medical ultrasonic transducer, can bridge the large acoustic impedance mismatch between the piezoelectric material and the human body. Composite materials are widely used as matching materials in order to cover the wide acoustic impedance range that cannot be accomplished by using a single-phase material. At high frequencies (>50 MHz), the {lambda}/4 matching layers become extremely thin so that the fabrication of homogeneous composite material matching layers becomes very challenging. A method is reported in this letter to fabricate sol-gel silicon oxide colloidal/polymer composite film on silicon substrate, in which the particle size of silicon oxide colloidal is between 10 and 40 nm. The acoustic impedance of the nanocomposite films versus aging temperature has been measured at the desired operating frequency.

  6. Silicon oxide colloidal/polymer nanocomposite films

    NASA Astrophysics Data System (ADS)

    Wang, Haifeng; Cao, Wenwu; Zhou, Q. F.; Shung, K. Kirk; Huang, Y. H.

    2004-12-01

    The quarter-wavelength (λ/4) acoustic matching layer, a vital component in medical ultrasonic transducer, can bridge the large acoustic impedance mismatch between the piezoelectric material and the human body. Composite materials are widely used as matching materials in order to cover the wide acoustic impedance range that cannot be accomplished by using a single-phase material. At high frequencies (>50MHz), the λ /4 matching layers become extremely thin so that the fabrication of homogeneous composite material matching layers becomes very challenging. A method is reported in this letter to fabricate sol-gel silicon oxide colloidal/polymer composite film on silicon substrate, in which the particle size of silicon oxide colloidal is between 10 and 40 nm. The acoustic impedance of the nanocomposite films versus aging temperature has been measured at the desired operating frequency.

  7. Water clustering on nanostructured iron oxide films.

    PubMed

    Merte, Lindsay R; Bechstein, Ralf; Peng, Guowen; Rieboldt, Felix; Farberow, Carrie A; Zeuthen, Helene; Knudsen, Jan; Lægsgaard, Erik; Wendt, Stefan; Mavrikakis, Manos; Besenbacher, Flemming

    2014-06-30

    The adhesion of water to solid surfaces is characterized by the tendency to balance competing molecule-molecule and molecule-surface interactions. Hydroxyl groups form strong hydrogen bonds to water molecules and are known to substantially influence the wetting behaviour of oxide surfaces, but it is not well-understood how these hydroxyl groups and their distribution on a surface affect the molecular-scale structure at the interface. Here we report a study of water clustering on a moiré-structured iron oxide thin film with a controlled density of hydroxyl groups. While large amorphous monolayer islands form on the bare film, the hydroxylated iron oxide film acts as a hydrophilic nanotemplate, causing the formation of a regular array of ice-like hexameric nanoclusters. The formation of this ordered phase is localized at the nanometre scale; with increasing water coverage, ordered and amorphous water are found to coexist at adjacent hydroxylated and hydroxyl-free domains of the moiré structure.

  8. Water Clustering on Nanostructured Iron Oxide Films

    SciTech Connect

    Merte, L. R.; Bechstein, Ralf; Peng, Guowen; Rieboldt, Felix; Farberow, Carrie A.; Zeuthen, Helene; Knudsen, Jan; Laegsgaard, E.; Wendt, Stefen; Mavrikakis, Manos; Besenbacher, Fleming

    2014-06-30

    The adhesion of water to solid surfaces is characterized by the tendency to balance competing molecule–molecule and molecule–surface interactions. Hydroxyl groups form strong hydrogen bonds to water molecules and are known to substantially influence the wetting behaviour of oxide surfaces, but it is not well-understood how these hydroxyl groups and their distribution on a surface affect the molecular-scale structure at the interface. Here we report a study of water clustering on a moire´-structured iron oxide thin film with a controlled density of hydroxyl groups. While large amorphous monolayer islands form on the are film, the hydroxylated iron oxide film acts as a hydrophilic nanotemplate, causing the formation of a regular array of ice-like hexameric nanoclusters. The formation of this ordered phase is localized at the nanometre scale; with increasing water coverage, ordered and amorphous water are found to coexist at adjacent hydroxylated and hydroxyl-free domains of the moire´ structure.

  9. Investigation of photoelectrochemical-oxidized p-GaSb films

    SciTech Connect

    Lee, Hsin-Ying; Huang, Hung-Lin; Lee, Ching-Ting; Petrovich Pchelyakov, Oleg; Andreevich Pakhanov, Nikolay

    2012-12-17

    GaSb oxide films were directly formed on the p-GaSb films using the bias-assisted photoelectrochemical (PEC) oxidation method. X-ray photoelectron spectroscopy analysis indicated that the resulting GaSb oxide films consisted of Ga{sub 2}O{sub 3}, Sb{sub 2}O{sub 3}, and Sb{sub 2}O{sub 5}. Different from the non-PEC oxides, the PEC derived oxide contained much more Sb{sub 2}O{sub 5} than Sb{sub 2}O{sub 3}. Besides, the interface state density between the PEC oxide and p-GaSb was lower than that of the ordinary oxide/p-GaSb interface. The high quality of the PEC-oxidized GaSb films was attributed to the increase of the stable Sb{sub 2}O{sub 5} content and decrease of the elemental Sb content in the films.

  10. Complex oxide thin films for microelectronics

    NASA Astrophysics Data System (ADS)

    Suvorova, Natalya

    The rapid scaling of the device dimensions, namely in metal oxide semiconductor field effect transistor (MOSFET), is reaching its fundamental limit which includes the increase in allowable leakage current due to direct tunneling with decrease of physical thickness of SiO2 gate dielectric. The significantly higher relative dielectric constant (in the range 9--25) of the gate dielectric beyond the 3.9 value of silicon dioxide will allow increasing the physical thickness. Among the choices for the high dielectric constant (K) materials for future generation MOSFET application, barium strontium titanate (BST) and strontium titanate (STO) possess one of the highest attainable K values making them the promising candidates for alternative gate oxide. However, the gate stack engineering does not imply the simple replacement of the SiO2 with the new dielectric. Several requirements should be met for successful integration of a new material. The major one is a production of high level of interface states (Dit) compared to that of SiO 2 on Si. An insertion of a thin SiO2 layer prior the growth of high-K thin film is a simple solution that helps to limit reaction with Si substrate and attains a high quality interface. However, the combination of two thin films reduces the overall K of the dielectric stack. An optimization of the SiO2 underlayer in order to maintain the interface quality yet minimize the effect on K is the focus of this work. The results from our study are presented with emphasis on the key process parameters that improve the dielectric film stack. For in-situ growth characterization of BST and STO films sputter deposited on thermally oxidized Si substrates spectroscopic ellipsometry in combination with time of flight ion scattering and recoil spectrometry have been employed. Studies of material properties have been complemented with analytical electron microscopy. To evaluate the interface quality the electrical characterization has been employed using

  11. Electrochromism: from oxide thin films to devices

    NASA Astrophysics Data System (ADS)

    Rougier, A.; Danine, A.; Faure, C.; Buffière, S.

    2014-03-01

    In respect of their adaptability and performance, electrochromic devices, ECDs, which are able to change their optical properties under an applied voltage, have received significant attention. Target applications are multifold both in the visible region (automotive sunroofs, smart windows, ophthalmic lenses, and domestic appliances (oven, fridge…)) and in the infrared region (Satellites Thermal Control, IR furtivity). In our group, focusing on oxide thin films grown preferentially at room temperature, optimization of ECDs performances have been achieved by tuning the microstructure, the stoichiometry and the cationic composition of the various layers. Herein, our approach for optimized ECDs is illustrated through the example of WO3 electrochromic layer in the visible and in the IR domain as well as ZnO based transparent conducting oxide layer. Targeting the field of printed electronics, simplification of the device architecture for low power ECDs is also reported.

  12. THE BEHAVIOR OF SUPERALLOY OXIDE FILMS IN MOLTEN SALTS.

    DTIC Science & Technology

    NICKEL ALLOYS , CORROSION), (*FILMS, OXIDES), CORROSION RESISTANT ALLOYS , SALTS, CORROSIVE LIQUIDS, HIGH TEMPERATURE, NICKEL COMPOUNDS, SODIUM...COMPOUNDS, SULFATES, CHLORIDES, CHROMIUM COMPOUNDS, CHROMIUM ALLOYS , MOLYBDENUM ALLOYS , COBALT ALLOYS , ALUMINUM ALLOYS , TITANIUM ALLOYS , IRON ALLOYS , NICKEL, OXIDATION

  13. Dysprosium oxide and dysprosium-oxide-doped titanium oxide thin films grown by atomic layer deposition

    SciTech Connect

    Tamm, Aile Kozlova, Jekaterina; Aarik, Lauri; Aarik, Jaan; Kukli, Kaupo; Link, Joosep; Stern, Raivo

    2015-01-15

    Dysprosium oxide and dysprosium-oxide-doped titanium oxide thin films were grown by atomic layer deposition on silicon substrates. For depositing dysprosium and titanium oxides Dy(thd){sub 3}-O{sub 3} and TiCl{sub 4}-O{sub 3} were used as precursors combinations. Appropriate parameters for Dy(thd){sub 3}-O{sub 3} growth process were obtained by using a quartz crystal microbalance system. The Dy{sub 2}O{sub 3} films were deposited on planar substrates and on three-dimensional substrates with aspect ratio 1:20. The Dy/Ti ratio of Dy{sub 2}O{sub 3}-doped TiO{sub 2} films deposited on a planar silicon substrate ranged from 0.04 to 0.06. Magnetometry studies revealed that saturation of magnetization could not be observed in planar Dy{sub 2}O{sub 3} films, but it was observable in Dy{sub 2}O{sub 3} films on 3D substrates and in doped TiO{sub 2} films with a Dy/Ti atomic ratio of 0.06. The latter films exhibited saturation magnetization 10{sup −6} A cm{sup 2} and coercivity 11 kA/m at room temperature.

  14. High carrier concentration p-type transparent conducting oxide films

    DOEpatents

    Yan, Yanfa; Zhang, Shengbai

    2005-06-21

    A p-type transparent conducting oxide film is provided which is consisting essentially of, the transparent conducting oxide and a molecular doping source, the oxide and doping source grown under conditions sufficient to deliver the doping source intact onto the oxide.

  15. Doping in zinc oxide thin films

    NASA Astrophysics Data System (ADS)

    Yang, Zheng

    Doping in zinc oxide (ZnO) thin films is discussed in this dissertation. The optimizations of undoped ZnO thin film growth using molecular-beam epitaxy (MBE) are discussed. The effect of the oxygen ECR plasma power on the growth rate, structural, electrical, and optical properties of the ZnO thin films were studied. It was found that larger ECR power leads to higher growth rate, better crystallinity, lower electron carrier concentration, larger resistivity, and smaller density of non-radiative luminescence centers in the ZnO thin films. Low-temperature photoluminescence (PL) measurements were carried out in undoped and Ga-doped ZnO thin films grown by molecular-beam epitaxy. As the carrier concentration increases from 1.8 x 1018 to 1.8 x 1020 cm-3, the dominant PL line at 9 K changes from I1 (3.368--3.371 eV), to IDA (3.317--3.321 eV), and finally to I8 (3.359 eV). The dominance of I1, due to ionized-donor bound excitons, is unexpected in n-type samples, but is shown to be consistent with the temperature-dependent Hall fitting results. We also show that IDA has characteristics of a donor-acceptor-pair transition, and use a detailed, quantitative analysis to argue that it arises from GaZn donors paired with Zn-vacancy (VZn) acceptors. In this analysis, the GaZn0/+ energy is well-known from two-electron satellite transitions, and the VZn0/- energy is taken from a recent theoretical calculation. Typical behaviors of Sb-doped p-type ZnO are presented. The Sb doping mechanisms and preference in ZnO are discussed. Diluted magnetic semiconducting ZnO:Co thin films with above room-temperature TC were prepared. Transmission electron microscopy and x-ray diffraction studies indicate the ZnO:Co thin films are free of secondary phases. The magnetization of the ZnO:Co thin films shows a free electron carrier concentration dependence, which increases dramatically when the free electron carrier concentration exceeds ˜1019 cm -3, indicating a carrier-mediated mechanism for

  16. p-type conduction in sputtered indium oxide films

    SciTech Connect

    Stankiewicz, Jolanta; Alcala, Rafael; Villuendas, Francisco

    2010-05-10

    We report p-type conductivity in intrinsic indium oxide (IO) films deposited by magnetron sputtering on fused quartz substrates under oxygen-rich ambient. Highly oriented (111) films were studied by x-ray diffraction, optical absorption, and Hall effect measurements. We fabricated p-n homojunctions on these films.

  17. Method of producing solution-derived metal oxide thin films

    SciTech Connect

    Boyle, T.J.; Ingersoll, D.

    2000-07-11

    A method is described for preparing metal oxide thin films by a solution method. A {beta}-metal {beta}-diketonate or carboxylate compound, where the metal is selected from groups 8, 9, 10, 11, and 12 of the Periodic Table, is solubilized in a strong Lewis base to form a homogeneous solution. This precursor solution forms within minutes and can be deposited on a substrate in a single layer or a multiple layers to form a metal oxide thin film. The substrate with the deposited thin film is heated to change the film from an amorphous phase to a ceramic metal oxide and cooled.

  18. Method of producing solution-derived metal oxide thin films

    DOEpatents

    Boyle, Timothy J.; Ingersoll, David

    2000-01-01

    A method of preparing metal oxide thin films by a solution method. A .beta.-metal .beta.-diketonate or carboxylate compound, where the metal is selected from groups 8, 9, 10, 11, and 12 of the Periodic Table, is solubilized in a strong Lewis base to form a homogeneous solution. This precursor solution forms within minutes and can be deposited on a substrate in a single layer or a multiple layers to form a metal oxide thin film. The substrate with the deposited thin film is heated to change the film from an amorphous phase to a ceramic metal oxide and cooled.

  19. Polymer-assisted aqueous deposition of metal oxide films

    DOEpatents

    Li, DeQuan [Los Alamos, NM; Jia, Quanxi [Los Alamos, NM

    2003-07-08

    An organic solvent-free process for deposition of metal oxide thin films is presented. The process includes aqueous solutions of necessary metal precursors and an aqueous solution of a water-soluble polymer. After a coating operation, the resultant coating is fired at high temperatures to yield optical quality metal oxide thin films.

  20. Effects of oxidative treatments on human hair keratin films.

    PubMed

    Fujii, T; Ito, Y; Watanabe, T; Kawasoe, T

    2012-01-01

    The effects of hydrogen peroxide and commercial bleach on hair and human hair keratin films were examined by protein solubility, scanning electron microscopy (SEM), immunofluorescence microscopy, immunoblotting, and Fourier-transform infrared spectroscopy. Protein solubility in solutions containing urea decreased when the keratin films were treated with hydrogen peroxide or bleach. Oxidative treatments promoted the urea-dependent morphological change by turning films from opaque to transparent in appearance. Immunofluorescence microscopy and immunoblotting showed that the oxidation of amino acids and proteins occurred due to the oxidative treatments, and such occurrence was more evident in the bleach-treated films than in the hydrogen peroxide-treated films. Compared with hair samples, the formation of cysteic acid was more clearly observed in the keratin films after the oxidative treatments.

  1. Characterization of gadolinium and lanthanum oxide films on Si (100)

    NASA Astrophysics Data System (ADS)

    Wu, X.; Landheer, D.; Sproule, G. I.; Quance, T.; Graham, M. J.; Botton, G. A.

    2002-05-01

    High-resolution transmission electron microscopy, electron energy loss spectroscopy, and Auger electron spectroscopy, were used to study gadolinium and lanthanum oxide films deposited on Si (100) substrates using electron-beam evaporation from pressed-powder targets. As-deposited films consist of a crystalline oxide layer and an amorphous interfacial layer. A complicated distinct multilayer structure consisting of oxide layers, silicate layers, and SiO2-rich layers in thick (~30 nm) annealed films has been observed for both gadolinium and lanthanum films. For thinner annealed films (~8 nm), there is no longer a crystalline oxide layer but an amorphous gadolinium or lanthanum silicate layer and an interfacial SiO2-rich layer. The formation of the lanthanum silicate by annealing lanthanum oxide is found to be thermodynamically more favorable than the formation of gadolinium silicate.

  2. Flexible electrostatic nanogenerator using graphene oxide film

    NASA Astrophysics Data System (ADS)

    Tian, He; Ma, Shuo; Zhao, Hai-Ming; Wu, Can; Ge, Jie; Xie, Dan; Yang, Yi; Ren, Tian-Ling

    2013-09-01

    Recently, graphene oxide (GO) super capacitors with ultra-high energy densities have received significant attention. In addition to their use in energy storage, GO capacitors might also have broad applications in renewable energy engineering, such as energy harvesting. Here, a flexible nanogenerator based on GO film is designed. A multilayer structure Al/PI/GO/PI/ITO is made on a flexible PET substrate. The GO nanogenerator could generate a peak voltage of 2 V with a current of 30 nA upon the repetitive application of a 15 N force with a frequency of 1 Hz. Moreover, the output voltage was increased to 34.4 V upon increasing the frequency of force application to 10 Hz. Compared with control samples, embedding GO film with a release structure into the device could significantly enhance the output voltage from 0.1 V to 2.0 V. The mechanism of our nanogenerator can be explained by an electrostatic effect, which is fundamentally different from that of previously reported piezoelectric and triboelectric generators. In this manuscript, we demonstrate flexible nanogenerators with large-area graphene based materials, which may open up new avenues of research with regard to applications in energy harvesting.Recently, graphene oxide (GO) super capacitors with ultra-high energy densities have received significant attention. In addition to their use in energy storage, GO capacitors might also have broad applications in renewable energy engineering, such as energy harvesting. Here, a flexible nanogenerator based on GO film is designed. A multilayer structure Al/PI/GO/PI/ITO is made on a flexible PET substrate. The GO nanogenerator could generate a peak voltage of 2 V with a current of 30 nA upon the repetitive application of a 15 N force with a frequency of 1 Hz. Moreover, the output voltage was increased to 34.4 V upon increasing the frequency of force application to 10 Hz. Compared with control samples, embedding GO film with a release structure into the device could

  3. Thin films for micro solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Beckel, D.; Bieberle-Hütter, A.; Harvey, A.; Infortuna, A.; Muecke, U. P.; Prestat, M.; Rupp, J. L. M.; Gauckler, L. J.

    Thin film deposition as applied to micro solid oxide fuel cell (μSOFC) fabrication is an emerging and highly active field of research that is attracting greater attention. This paper reviews thin film (thickness ≤1 μm) deposition techniques and components relevant to SOFCs including current research on nanocrystalline thin film electrolyte and thin-film-based model electrodes. Calculations showing the geometric limits of μSOFCs and first results towards fabrication of μSOFCs are also discussed.

  4. Review of Zinc Oxide Thin Films

    DTIC Science & Technology

    2014-12-23

    Laboratory Air Force Materiel Command   a. REPORT U   b. ABSTRACT U   c. THIS PAGE U REPORT DOCUMENTATION PAGE Form ApprovedOMB No. 0704-0188 The public...PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ORGANIZATION. 1.  REPORT DATE (DD-MM-YYYY)      18-12-2014 2.  REPORT TYPE      Final Performance 3.  DATES...Standard Form 298 (Rev. 8/98) Prescribed by ANSI Std. Z39.18 1    Review of Zinc Oxide Thin Films   Abstract  The present review paper reports on the

  5. Epitaxial Electrodeposition of Chiral Metal Oxide Films

    NASA Astrophysics Data System (ADS)

    Switzer, Jay

    2006-03-01

    Chirality is ubiquitous in Nature. One enantiomer of a molecule is often physiologically active, while the other enantiomer may be either inactive or toxic. Chiral surfaces offer the possibility of developing heterogeneous enantiospecific catalysts that can more readily be separated from the products and reused. Chiral surfaces might also serve as electrochemical sensors for chiral molecules- perhaps even implantable chiral sensors that could be used to monitor drug levels in the body. Our trick to produce chiral surfaces is to electrodeposit low symmetry metal oxide films with chiral orientations on achiral substrates (see, Nature 425, 490, 2003). The relationship between three-dimensional and two-dimensional chirality will be discussed. Chiral surfaces lack mirror or glide plane symmetry. It is possible to produce chiral surfaces of materials which do not crystallize in chiral space groups. We have deposited chiral orientations of achiral CuO onto single-crystal Au and Cu using both tartaric acid and the amino acids alanine and valine to control the handedness of the electrodeposited films. We will present results on the chiral recognition of molecules such as tartaric or malic acid and L-dopa on the chiral electrodeposited CuO. Initial work on the electrochemical biomineralization of chiral nanostructures of calcite will also be discussed.

  6. Flexible electrostatic nanogenerator using graphene oxide film.

    PubMed

    Tian, He; Ma, Shuo; Zhao, Hai-Ming; Wu, Can; Ge, Jie; Xie, Dan; Yang, Yi; Ren, Tian-Ling

    2013-10-07

    Recently, graphene oxide (GO) super capacitors with ultra-high energy densities have received significant attention. In addition to their use in energy storage, GO capacitors might also have broad applications in renewable energy engineering, such as energy harvesting. Here, a flexible nanogenerator based on GO film is designed. A multilayer structure Al/PI/GO/PI/ITO is made on a flexible PET substrate. The GO nanogenerator could generate a peak voltage of 2 V with a current of 30 nA upon the repetitive application of a 15 N force with a frequency of 1 Hz. Moreover, the output voltage was increased to 34.4 V upon increasing the frequency of force application to 10 Hz. Compared with control samples, embedding GO film with a release structure into the device could significantly enhance the output voltage from 0.1 V to 2.0 V. The mechanism of our nanogenerator can be explained by an electrostatic effect, which is fundamentally different from that of previously reported piezoelectric and triboelectric generators. In this manuscript, we demonstrate flexible nanogenerators with large-area graphene based materials, which may open up new avenues of research with regard to applications in energy harvesting.

  7. Crystalline state and acoustic properties of zinc oxide films

    SciTech Connect

    Kal'naya, G.I.; Pryadko, I.F.; Yarovoi, Yu.A.

    1988-08-01

    We study the effect of the crystalline state of zinc oxide films, prepared by magnetron sputtering, on the efficiency of SAW transducers based on the layered system textured ZnO film-interdigital transducer (IDT)-fused quartz substrate. The crystalline perfection of the ZnO films was studied by the x-ray method using a DRON-2.0 diffractometer. The acoustic properties of the layered system fused quartz substrate-IDT-zinc oxide film were evaluated based on the squared electromechanical coupling constant K/sup 2/ for strip filters. It was found that K/sup 2/ depends on the magnitude of the mechanical stresses. When zinc oxide films are deposited by the method of magnetron deposition on fused quartz substrates, depending on the process conditions limitations can arise on the rate of deposition owing to mechanical stresses, which significantly degrade the efficiency of SAW transducers based on them, in the ZnO films.

  8. Amorphous tin-cadmium oxide films and the production thereof

    SciTech Connect

    Li, Xiaonan; Gessert, Timothy A

    2013-10-29

    A tin-cadmium oxide film having an amorphous structure and a ratio of tin atoms to cadmium atoms of between 1:1 and 3:1. The tin-cadmium oxide film may have an optical band gap of between 2.7 eV and 3.35 eV. The film may also have a charge carrier concentration of between 1.times.10.sup.20 cm.sup.-3 and 2.times.10.sup.20 cm.sup.-3. The tin cadmium oxide film may also exhibit a Hall mobility of between 40 cm.sup.2V.sup.-1 s.sup.-1 and 60 cm.sup.2V.sup.-1 s.sup.-1. Also disclosed is a method of producing an amorphous tin-cadmium oxide film as described and devices using same.

  9. Rapid Deposition of Titanium Oxide and Zinc Oxide Films by Solution Precursor Plasma Spray

    NASA Astrophysics Data System (ADS)

    Ando, Yasutaka

    In order to develop a high rate atmospheric film deposition process for functional films, as a basic study, deposition of titanium oxide film and zinc oxide film by solution precursor plasma spray (SPPS) was conducted in open air. Consequently, in the case of titanium oxide film deposition, anantase film and amorphous film as well as rutile film could be deposited by varying the deposition distance. In the case of anatase dominant film, photo-catalytic properties of the films could be confirmed by wettability test. In addition, the dye sensitized sollar cell (DSC) using the TiO2 film deposited by this SPPS technique as photo voltaic device generates 49mV in OCV. On the other hand, in the case of zinc oxide film deposition, it was proved that well crystallized ZnO films with photo catalytic properties could be deposited. From these results, this process was found to have high potential for high rate functional film deposition process conducted in the air.

  10. Active Oxygen Generator by Silent Discharge and Oxidation Power in Formation of Oxide Thin Films

    NASA Astrophysics Data System (ADS)

    Tanaka, Masaaki; Kawagoe, Yasuyuki; Tsukazaki, Hisashi; Yamanishi, Kenichiro

    We have studied the low pressure silent discharge type active oxygen generator in terms of the application to the formation of oxide thin films. In this paper the oxidation power of active oxygen in the oxide thin film formation is compared with that of oxygen and ozone by forming silicon oxide thin films. It was confirmed that the oxidation power is in turn of active oxygen > ozone > oxygen from the experimental result of the number of x in SiOx thin film. Furthermore we applied active oxygen to the formation of the thin film high temperature super conductor and active oxygen was found to be effective to the formation of the thin film with high performance.

  11. Visible light-induced photocatalytic reduction of graphene oxide by tungsten oxide thin films

    NASA Astrophysics Data System (ADS)

    Choobtashani, M.; Akhavan, O.

    2013-07-01

    Tungsten oxide thin films (deposited by thermal evaporation or sol gel method) were used for photocatalytic reduction of graphene oxide (GO) platelets (synthesized through a chemical exfoliation method) on surface of the films under UV or visible light of the environment, in the absence of any aqueous ambient at room temperature. Atomic force microscopy (AFM) technique was employed to characterize surface morphology of the GO sheets and the tungsten oxide films. Moreover, using X-ray photoelectron spectroscopy (XPS), chemical state of the tungsten oxide films and the photocatalytic reduction of the GO platelets were quantitatively investigated. The better performance of the sol-gel tungsten oxide films in photocatalytic reduction of GO platelets as compared to the evaporated tungsten oxide films was assigned to lower W5+/W6+ ratio (i.e., a better stoichiometry) and higher surface water content of the sol-gel film. The GO reduction level achieved after 24 h UV-assisted photocatalytic reduction on surface of the sol-gel tungsten oxide film was comparable with the reduction level usually obtainable by hydrazine. The sol-gel tungsten oxide film even showed an efficient photocatalytic reduction of the GO platelets after exposure to the visible light of the environment for 2 days.

  12. Films based on oxidized starch and cellulose from barley.

    PubMed

    El Halal, Shanise Lisie Mello; Colussi, Rosana; Deon, Vinícius Gonçalves; Pinto, Vânia Zanella; Villanova, Franciene Almeida; Carreño, Neftali Lenin Villarreal; Dias, Alvaro Renato Guerra; Zavareze, Elessandra da Rosa

    2015-11-20

    Starch and cellulose fibers were isolated from grains and the husk from barley, respectively. Biodegradable films of native starch or oxidized starches and glycerol with different concentrations of cellulose fibers (0%, 10% and 20%) were prepared. The films were characterized by morphological, mechanical, barrier, and thermal properties. Cellulose fibers isolated from the barley husk were obtained with 75% purity and high crystallinity. The morphology of the films of the oxidized starches, regardless of the fiber addition, was more homogeneous as compared to the film of the native starch. The addition of cellulose fibers in the films increased the tensile strength and decreased elongation. The water vapor permeability of the film of oxidized starch with 20% of cellulose fibers was lower than the without fibers. However the films with cellulose fibers had the highest decomposition with the initial temperature and thermal stability. The oxidized starch and cellulose fibers from barley have a good potential for use in packaging. The addition of cellulose fibers in starch films can contribute to the development of films more resistant that can be applied in food systems to maintain its integrity.

  13. Aerosol chemical vapor deposition of metal oxide films

    DOEpatents

    Ott, Kevin C.; Kodas, Toivo T.

    1994-01-01

    A process of preparing a film of a multicomponent metal oxide including: forming an aerosol from a solution comprised of a suitable solvent and at least two precursor compounds capable of volatilizing at temperatures lower than the decomposition temperature of said precursor compounds; passing said aerosol in combination with a suitable oxygen-containing carrier gas into a heated zone, said heated zone having a temperature sufficient to evaporate the solvent and volatilize said precursor compounds; and passing said volatilized precursor compounds against the surface of a substrate, said substrate having a sufficient temperature to decompose said volatilized precursor compounds whereby metal atoms contained within said volatilized precursor compounds are deposited as a metal oxide film upon the substrate is disclosed. In addition, a coated article comprising a multicomponent metal oxide film conforming to the surface of a substrate selected from the group consisting of silicon, magnesium oxide, yttrium-stabilized zirconium oxide, sapphire, or lanthanum gallate, said multicomponent metal oxide film characterized as having a substantially uniform thickness upon said FIELD OF THE INVENTION The present invention relates to the field of film coating deposition techniques, and more particularly to the deposition of multicomponent metal oxide films by aerosol chemical vapor deposition. This invention is the result of a contract with the Department of Energy (Contract No. W-7405-ENG-36).

  14. Low reflectance sputtered vanadium oxide thin films on silicon

    NASA Astrophysics Data System (ADS)

    Esther, A. Carmel Mary; Dey, Arjun; Rangappa, Dinesh; Sharma, Anand Kumar

    2016-07-01

    Vanadium oxide thin films on silicon (Si) substrate are grown by pulsed radio frequency (RF) magnetron sputtering technique at RF power in the range of 100-700 W at room temperature. Deposited thin films are characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques to investigate microstructural, phase, electronic structure and oxide state characteristics. The reflectance and transmittance spectra of the films and the Si substrate are recorded at the solar region (200-2300 nm) of the spectral window. Substantial reduction in reflectance and increase in transmittance is observed for the films grown beyond 200 W. Further, optical constants viz. absorption coefficient, refractive index and extinction coefficient of the deposited vanadium oxide films are evaluated.

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

    SciTech Connect

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

    2015-07-15

    Highlights: • Thin films of ceria doped by rhodium deposited by RF magnetron sputtering. • Concentration of rhodium has great impact on properties of Rh–CeO{sub 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{sub 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{sup 4+} and Ce{sup 3+} and rhodium occurs in two oxidation states, Rh{sup 3+} and Rh{sup n+}. We show that the concentration of rhodium has a great influence on the chemical composition, structure and reducibility of the Rh–CeO{sub 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{sub x} thin films leads to preparing materials with different properties.

  16. Method for producing high quality oxide films on substrates

    DOEpatents

    Ruckman, M.W.; Strongin, M.; Gao, Y.L.

    1993-11-23

    A method is described for providing an oxide film of a material on the surface of a substrate using a reactive deposition of the material onto the substrate surface in the presence of a solid or liquid layer of an oxidizing gas. The oxidizing gas is provided on the substrate surface in an amount sufficient to dissipate the latent heat of condensation occurring during deposition as well as creating a favorable oxidizing environment for the material. 4 figures.

  17. Method for producing high quality oxide films on substrates

    DOEpatents

    Ruckman, Mark W.; Strongin, Myron; Gao, Yong L.

    1993-01-01

    A method for providing an oxide film of a material on the surface of a substrate using a reactive deposition of the material onto the substrate surface in the presence of a solid or liquid layer of an oxidizing gas. The oxidizing gas is provided on the substrate surface in an amount sufficient to dissipate the latent heat of condensation occurring during deposition as well as creating a favorable oxidizing environment for the material.

  18. Lateral solid-phase epitaxy of oxide thin films on glass substrate seeded with oxide nanosheets.

    PubMed

    Taira, Kenji; Hirose, Yasushi; Nakao, Shoichiro; Yamada, Naoomi; Kogure, Toshihiro; Shibata, Tatsuo; Sasaki, Takayoshi; Hasegawa, Tetsuya

    2014-06-24

    We developed a technique to fabricate oxide thin films with uniaxially controlled crystallographic orientation and lateral size of more than micrometers on amorphous substrates. This technique is lateral solid-phase epitaxy, where epitaxial crystallization of amorphous precursor is seeded with ultrathin oxide nanosheets sparsely (≈10% coverage) deposited on the substrate. Transparent conducting Nb-doped anatase TiO2 thin films were fabricated on glass substrates by this technique. Perfect (001) orientation and large grains with lateral sizes up to 10 μm were confirmed by X-ray diffraction, atomic force microscopy, and electron beam backscattering diffraction measurements. As a consequence of these features, the obtained film exhibited excellent electrical transport properties comparable to those of epitaxial thin films on single-crystalline substrates. This technique is a versatile method for fabricating high-quality oxide thin films other than anatase TiO2 and would increase the possible applications of oxide-based thin film devices.

  19. Unidirectional oxide hetero-interface thin-film diode

    SciTech Connect

    Park, Youngmin; Lee, Eungkyu; Lee, Jinwon; Lim, Keon-Hee; Kim, Youn Sang

    2015-10-05

    The unidirectional thin-film diode based on oxide hetero-interface, which is well compatible with conventional thin-film fabrication process, is presented. With the metal anode/electron-transporting oxide (ETO)/electron-injecting oxide (EIO)/metal cathode structure, it exhibits that electrical currents ohmically flow at the ETO/EIO hetero-interfaces for only positive voltages showing current density (J)-rectifying ratio of ∼10{sup 5} at 5 V. The electrical properties (ex, current levels, and working device yields) of the thin-film diode (TFD) are systematically controlled by changing oxide layer thickness. Moreover, we show that the oxide hetero-interface TFD clearly rectifies an AC input within frequency (f) range of 10{sup 2} Hz < f < 10{sup 6} Hz, providing a high feasibility for practical applications.

  20. Two kinds of composite films: Graphene oxide/carbon nanotube film and graphene oxide/activated carbon film via a self-assemble preparation process

    NASA Astrophysics Data System (ADS)

    Zou, Li-feng; Ma, Nan; Sun, Mei; Ji, Tian-hao

    2014-11-01

    Two kinds of free-standing composite films, including graphene oxide and activated carbon film as well as graphene oxide and carbon nanotube film, were fabricated through a simple suspension mixing and then natural deposition process. The films were characterized by various measurement techniques in detail. The results show that the composite films without any treatment almost still remain the original properties of the corresponding precursors, and exhibit loose structure, which can be easily broken in water; whereas after treated at 200 °C in air, the films become relatively more dense, and even if immersed into concentrated strong alkali or acid for five days, they still keep the film-morphologies, but regretfully, they show obvious brittleness and slight hydrophilicity. As soon as the treated films are performed in high concentrated strong alkali for about one day, their brittleness and wettability can be improved and became good flexibility and complete hydrophilicity.

  1. Thin film zinc oxide deposited by CVD and PVD

    NASA Astrophysics Data System (ADS)

    Hamelmann, Frank U.

    2016-10-01

    Zinc oxide is known as a mineral since 1810, but it came to scientific interest after its optoelectronic properties found to be tuneable by p-type doping. Since the late 1980’s the number of publications increased exponentially. All thin film deposition technologies, including sol-gel and spray pyrolysis, are able to produce ZnO films. However, for outstanding properties and specific doping, only chemical vapor deposition and physical vapor deposition have shown so far satisfying results in terms of high conductivity and high transparency. In this paper the different possibilities for doping will be discussed, some important applications of doped ZnO thin films will be presented. The deposition technologies used for industrial applications are shown in this paper. Especially sputtering of aluminium doped Zinc Oxide (ZnO:Al or AZO) and LPCVD of boron doped Zinc Oxide (ZnO:B or BZO) are used for the commercial production of transparent conductive oxide films on glass used for thin film photovoltaic cells. For this special application the typical process development for large area deposition is presented, with the important trade-off between optical properties (transparency and ability for light scattering) and electrical properties (conductivity). Also, the long term stability of doped ZnO films is important for applications, humidity in the ambient is often the reason for degradation of the films. The differences between the mentioned materials are presented.

  2. Structural characterization of impurified zinc oxide thin films

    SciTech Connect

    Trinca, L. M.; Galca, A. C. Stancu, V. Chirila, C. Pintilie, L.

    2014-11-05

    Europium doped zinc oxide (Eu:ZnO) thin films have been obtained by pulsed laser deposition (PLD). 002 textured thin films were achieved on glass and silicon substrates, while hetero-epilayers and homo-epilayers have been attained on single crystal SrTiO{sub 3} and ZnO, respectively. X-ray Diffraction (XRD) was employed to characterize the Eu:ZnO thin films. Extended XRD studies confirmed the different thin film structural properties as function of chosen substrates.

  3. Study of indium tin oxide films exposed to atomic axygen

    NASA Technical Reports Server (NTRS)

    Snyder, Paul G.; De, Bhola N.; Woollam, John A.; Coutts, T. J.; Li, X.

    1989-01-01

    A qualitative simulation of the effects of atomic oxygen has been conducted on indium tin oxide (ITO) films prepared by dc sputtering onto room-temperature substrates, by exposing them to an RF-excited oxygen plasma and characterizing the resulting changes in optical, electrical, and structural properties as functions of exposure time with ellipsometry, spectrophotometry, resistivity, and X-ray measurements. While the films thus exposed exhibit reduced resistivity and optical transmission; both of these effects, as well as partial crystallization of the films, may be due to sample heating by the plasma. Film resistivity is found to stabilize after a period of exposure.

  4. Study of indium tin oxide films exposed to atomic axygen

    NASA Technical Reports Server (NTRS)

    Snyder, Paul G.; De, Bhola N.; Woollam, John A.; Coutts, T. J.; Li, X.

    1989-01-01

    A qualitative simulation of the effects of atomic oxygen has been conducted on indium tin oxide (ITO) films prepared by dc sputtering onto room-temperature substrates, by exposing them to an RF-excited oxygen plasma and characterizing the resulting changes in optical, electrical, and structural properties as functions of exposure time with ellipsometry, spectrophotometry, resistivity, and X-ray measurements. While the films thus exposed exhibit reduced resistivity and optical transmission; both of these effects, as well as partial crystallization of the films, may be due to sample heating by the plasma. Film resistivity is found to stabilize after a period of exposure.

  5. Ordered fragmentation of oxide thin films at submicron scale

    PubMed Central

    Guo, L.; Ren, Y.; Kong, L. Y.; Chim, W. K.; Chiam, S. Y.

    2016-01-01

    Crack formation is typically undesirable as it represents mechanical failure that compromises strength and integrity. Recently, there have also been numerous attempts to control crack formation in materials with the aim to prevent or isolate crack propagation. In this work, we utilize fragmentation, at submicron and nanometre scales, to create ordered metal oxide film coatings. We introduce a simple method to create modified films using electroplating on a prepatterned substrate. The modified films undergo preferential fragmentation at locations defined by the initial structures on the substrate, yielding ordered structures. In thicker films, some randomness in the characteristic sizes of the fragments is introduced due to competition between crack propagation and crack creation. The method presented allows patterning of metal oxide films over relatively large areas by controlling the fragmentation process. We demonstrate use of the method to fabricate high-performance electrochromic structures, yielding good coloration contrast and high coloration efficiency. PMID:27748456

  6. Tungsten-vanadium oxide sputtered films for Electrochromic Devices

    SciTech Connect

    Michalak, F.; Richardson, T.; Rubin, M.; Slack, J.; von Rottkay, K.

    1998-10-01

    Mixed vanadium and tungsten oxide films with compositions ranging from 0 to 100% vanadium (metals basis) were prepared by reactive sputtering from metallic vanadium and tungsten targets in an atmosphere of argon and oxygen. The vanadium content varied smoothly with the fraction of total power applied to the vanadium target. Films containing vanadium were more color neutral than pure tungsten oxide films, tending to gray-brown at high V fraction. The electrochromic switching performance of these films was investigated by in situ monitoring of their visible transmittance during lithium insertion/extraction cycling in a non-aqueous electrolyte (1M LiClO{sub 4} in propylene carbonate). The solar transmittance and reflectance was measured ex situ. Films with vanadium content greater than about 15% exhibited a marked decrease in switching range. Coloration efficiencies followed a similar trend.

  7. Understanding Organic Film Behavior on Alloy and Metal Oxides

    PubMed Central

    Raman, Aparna; Quiñones, Rosalynn; Barriger, Lisa; Eastman, Rachel; Parsi, Arash

    2010-01-01

    Native oxide surfaces of stainless steel 316L and Nitinol alloys and their constituent metal oxides namely, nickel, chromium, molybdenum, manganese, iron and titanium were modified with long chain organic acids to better understand organic film formation. The adhesion and stability of films of octadecylphosphonic acid, octadecylhydroxamic acid, octadecylcarboxylic acid and octadecylsulfonic acid on these substrates was examined in this study. The films formed on these surfaces were analyzed by diffuse reflectance infrared Fourier transform spectroscopy, contact angle goniometry, atomic force microscopy and matrix assisted laser desorption ionization mass spectrometry. The effect of the acidity of the organic moiety and substrate composition on the film characteristics and stability is discussed. Interestingly, on the alloy surfaces, the presence of less reactive metal sites does not inhibit film formation. PMID:20039608

  8. Low temperature oxidation mechanisms of nanocrystalline magnetite thin film

    SciTech Connect

    Bourgeois, F.; Gergaud, P.; Feuillet, G.; Renevier, H.; Leclere, C.

    2013-01-07

    A detailed investigation of the mechanisms related to the low temperature oxidation of nanocrystalline magnetite thin films into maghemite is presented. Despite strong differences in the functional properties of these two phases, structural similarities make it difficult to distinguish between them, and to quantify the oxidation process, particularly in the case of nanostructured polycrystalline layers. Contrary to the case of bulk materials or monocrystalline films and particles, the oxidation processes in nanocrystalline thin film have only scarcely been studied. In this work, structural and optical techniques, including X-ray diffraction (XRD), EXAFS/X-ray absorption near edge structure, FTIR, and Raman scattering, have been used to estimate the oxidation rate of magnetite. The overall oxidation reaction rates are discussed in the framework of two limiting cases corresponding to intra grain diffusion and to grain boundary diffusion. SIMS profiling and electrical measurements were also carried out to better assess the oxidation quantification in order to conclude on the predominant oxidation mechanisms in this heterogeneous material. We propose a qualitative model for the structure, in terms of insulating zone distribution, for partially oxidized films.

  9. Reactive pulsed magnetron-sputtered tantalum oxide thin films

    NASA Astrophysics Data System (ADS)

    Nielsen, Matthew Christian

    Current high speed, advanced packaging applications require the use of integrated capacitors. Tantalum oxide is one material currently being considered for use in the capacitors; however, the deposition technique used to make the thin film dielectric can alter its performance. Pulsed magnetron reactive sputtering was investigated in this thesis as it offers a robust, clean, and low temperature deposition alternative. This is a new deposition technique created to control the negative effects of target poisoning; however, to understand the relationships between the deposition variables and the resultant film properties a thorough investigation is needed. The instantaneous voltage at the target was captured using a high speed digital oscilloscope. Three target oxidation states were imaged and identified to be that of the metallic and oxidized states with an abrupt transition region separating the two. Using high resolution X-ray photoelectron spectroscopy the bonding present in the deposited films was correlated to the oxidation state of the target. While operating the target in the metallic mode, a mix of oxidized, sub-oxide and metallic states were discovered. Alternatively, the bonding present in the films deposited when the target was in the oxidized state were that of fully oxidized tantalum pentoxide. The films deposited above the critical partial pressure demonstrated excellent leakage current densities. The exact magnitude of the leakage current density inversely scaled to the relative amount of oxygen included into the sputtering atmosphere. Detailed plot analysis showed that there were two different conduction mechanisms controlling the current flow in the capacitors. High frequency test vehicles were measured up to 10 GHz in order to determine the frequency response of the dielectric material. A circuit equivalent model describing the testing system and samples was created and utilized to fit the collected data. Overall, the technique of pulsed magnetron

  10. Preparation of crystalline tungsten oxide films from organometallic precursors

    SciTech Connect

    Meda, L.; Kirss, R.U.

    1995-12-31

    Thin films of tungsten oxide, WO{sub 3}, are of interest in the preparation of electrochromic display devices. Chemical vapor deposition experiments using tetra(allyl)tungsten, W({eta}{sup 3}-C{sub 3}H{sub 5}){sub 4}, led to the deposition of dark, reflective, amorphous carbon rich tungsten/tungsten carbide films on SiO{sub 2} glass between 250 and 450{degrees}C. When {approx}0.25 {mu} thick films were annealed at 400{degrees}C under oxygen, conversion to transparent, nearly colorless, crystalline WO{sub 3} was observed. The films were characterized by x-ray diffraction, SEM and ESCA. Shorter reaction times and lower temperatures yielded dark blue, amorphous films characteristic of WO{sub 3-n} films. The smooth blue films were characterized by SEM and ESCA. While the crystalline WO{sub 3} films were found to be electrically insulating, the blue films were found to be electrically conductive. Preliminary results on the conversion of the WO{sub 3} films to tungsten sulfide and tungsten selenide films will be discussed.

  11. High temperature coefficient of resistance molybdenum oxide and nickel oxide thin films for microbolometer applications

    NASA Astrophysics Data System (ADS)

    Jin, Yao O.; John, David Saint; Podraza, Nikolas J.; Jackson, Thomas N.; Horn, Mark W.

    2015-03-01

    Molybdenum oxide (MoOx) and nickel oxide (NiOx) thin films were deposited by reactive biased target ion beam deposition. MoOx thin film resistivity varied from 3 to 2000 Ω.cm with a temperature coefficient of resistance (TCR) from -1.7% to -3.2%/K, and NiOx thin film resistivity varied from 1 to 300 Ω.cm with a TCR from -2.2% to -3.3%/K, both easily controlled by varying the oxygen partial pressure. Biased target ion beam deposited high TCR MoOx and NiOx thin films are polycrystalline semiconductors and have good stability in air. Compared with commonly used vanadium oxide thin films, MoOx or NiOx thin films offer improved process control for resistive temperature sensors.

  12. Conductive metal oxide film and method of making

    SciTech Connect

    Windisch, Jr., Charles F.; Exarhos, Gregory J.

    1999-01-01

    The present invention is a method for reducing a dopant in a film of a metal oxide wherein the dopant is reduced and the first metal oxide is substantially not reduced. The method of the present invention relies upon exposing the film to reducing conditions for a predetermined time and reducing a valence of the metal from a positive valence to a zero valence and maintaining atoms with a zero valence in an atomic configuration within the lattice structure of the metal oxide. According to the present invention, exposure to reducing conditions may be achieved electrochemically or achieved in an elevated temperature gas phase.

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

    SciTech Connect

    Coloma Ribera, R. Kruijs, R. W. E. van de; Yakshin, A. E.; Bijkerk, F.

    2015-08-07

    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 RuO{sub 2} films were found to show Arrhenius behaviour. However, a gradual decrease in diffusion rates was observed with oxide growth, with the activation energy increasing from about 2.1 to 2.4 eV. Further exploration of the Arrhenius pre-exponential factor for diffusion process revealed that oxidation of polycrystalline ruthenium joins the class of materials that obey the Meyer-Neldel rule.

  14. Tungsten oxide-cellulose nanocrystal composite films for electrochromic applications

    NASA Astrophysics Data System (ADS)

    Stoenescu, Stefan; Badilescu, Simona; Sharma, Tanu; Brüning, Ralf; Truong, Vo-Van

    2016-12-01

    Composite films of tungsten oxide and CNCs are prepared through a sol-gel method and their electrochromic (EC) properties investigated. After mixing CNC gel into a tungsten oxide precursor solution, indium-tin-oxide-coated glass substrates are dipped into the composite solution and subsequently annealed at 170°C. The composite films consisted of CNCs dispersed in the tungsten oxide matrix. The resulting nanocomposite was found to be amorphous, exhibiting a high transmission modulation and very good cycling stability. After having tested a range of compositions, a film of WO3 with 10% CNC was found to be the most uniform and showed good EC performance. These results bode well for further work on CNC-EC composites for specific applications, especially when used on flexible substrates.

  15. High stability mechanisms of quinary indium gallium zinc aluminum oxide multicomponent oxide films and thin film transistors

    SciTech Connect

    Lee, Ching-Ting Lin, Yung-Hao; Lin, Jhong-Ham

    2015-01-28

    Quinary indium gallium zinc aluminum oxide (IGZAO) multicomponent oxide films were deposited using indium gallium zinc oxide (IGZO) target and Al target by radio frequency magnetron cosputtering system. An extra carrier transport pathway could be provided by the 3 s orbitals of Al cations to improve the electrical properties of the IGZO films, and the oxygen instability could be stabilized by the strong Al-O bonds in the IGZAO films. The electron concentration change and the electron mobility change of the IGZAO films for aging time of 10 days under an air environment at 40 °C and 75% humidity were 20.1% and 2.4%, respectively. The experimental results verified the performance stability of the IGZAO films. Compared with the thin film transistors (TFTs) using conventional IGZO channel layer, in conducting the stability of TFTs with IGZAO channel layer, the transconductance g{sub m} change, threshold voltage V{sub T} change, and the subthreshold swing S value change under the same aging condition were improved to 7.9%, 10.5%, and 14.8%, respectively. Furthermore, the stable performances of the IGZAO TFTs were also verified by the positive gate bias stress. In this research, the quinary IGZAO multicomponent oxide films and that applied in TFTs were the first studied in the literature.

  16. Porous nickel oxide films for electrochemical capacitors

    SciTech Connect

    Liu, K.C.; Anderson, M.A.

    1995-12-31

    NiO/Ni composite thin films consisting of nano-sized particles have been found to perform as good electrodes in electrochemical capacitor applications. These films can provide a specific capacitance of 25--40 F/g. The low cost of raw materials and easy manufacturing process of this system should allow one to produce low-cost electrochemical capacitors.

  17. Sputter-deposited low reflectance vanadium oxide-molybdenum oxide thin films on silicon

    NASA Astrophysics Data System (ADS)

    Nayak, Manish Kumar; Esther, A. Carmel Mary; Bera, Parthasarathi; Dey, Arjun

    2017-09-01

    A single layer antireflective, smart, crystalline and nanocolumnar pulsed RF magnetron sputtered vanadium oxide-molybdenum oxide thin film on silicon is proposed for the alternate antireflective material for silicon based futuristic solar cell application. The VO-MO film with 130 nm thickness grown at 200 W shows significant low reflectance (1% within the 500-600 nm region). The VO-MO film with lowest reflectance shows a phase transition at around 55 °C which is beneficial due to film inherent variable IR emittance behaviour which may be helpful for eliminating excess heat load generated during in-service of silicon solar cell.

  18. Pulsed photonic fabrication of nanostructured metal oxide thin films

    NASA Astrophysics Data System (ADS)

    Bourgeois, Briley B.; Luo, Sijun; Riggs, Brian C.; Adireddy, Shiva; Chrisey, Douglas B.

    2017-09-01

    Nanostructured metal oxide thin films with a large specific surface area are preferable for practical device applications in energy conversion and storage. Herein, we report instantaneous (milliseconds) photonic synthesis of three-dimensional (3-D) nanostructured metal oxide thin films through the pulsed photoinitiated pyrolysis of organometallic precursor films made by chemical solution deposition. High wall-plug efficiency-pulsed photonic irradiation (xenon flash lamp, pulse width of 1.93 ms, fluence of 7.7 J/cm2 and frequency of 1.2 Hz) is used for scalable photonic processing. The photothermal effect of subsequent pulses rapidly improves the crystalline quality of nanocrystalline metal oxide thin films in minutes. The following paper highlights pulsed photonic fabrication of 3-D nanostructured TiO2, Co3O4, and Fe2O3 thin films, exemplifying a promising new method for the low-cost and high-throughput manufacturing of nanostructured metal oxide thin films for energy applications.

  19. Synthesis and Oxidation Resistance of h-BN Thin Films

    NASA Astrophysics Data System (ADS)

    Stewart, David; Meulenberg, Robert; Lad, Robert

    Hexagonal boron nitride (h-BN) is an exciting 2D material for use in sensors and other electronic devices that operate in harsh, high temperature environments. Not only is h-BN a wide band gap material with excellent wear resistance and high temperature stability, but recent reports indicate that h-BN can prevent metallic substrates from oxidizing above 600°C in low O2 pressures. However, the PVD of highly crystalline h-BN films required for this oxidation protection has proven challenging. In this work, we have explored the growth of h-BN thin films by reactive RF magnetron sputtering from an elemental B target in an Ar/N2 atmosphere. The film growth rate is extremely slow and the resulting films are atomically smooth and homogeneous. Using DC biasing during deposition and high temperature annealing treatments, the degree of film crystallinity can be controlled. The oxidation resistance of h-BN films deposited on inert sapphire and reactive metal substrates such as Zr and ZrB2 has been examined by techniques such as XPS, XRD, and SEM after oxidation between 600 and 1200°C under varying oxygen pressures. The success of h-BN as a passivation layer for metallic substrates in harsh environments is shown to depend greatly on its crystalline quality and defects. Supported by the NSF SusChEM program.

  20. Tungsten oxide thin films: detection and trapping of hazardous gases

    NASA Astrophysics Data System (ADS)

    Godbole, Rhushikesh; Vedpathak, Amol; Godbole, Vijay; Bhagwat, Sunita

    2017-07-01

    Synthesis of tungsten (W) and tungsten tri-oxide (WO3) thin films on alumina substrate by a peculiar Red-ox reaction route using hot-filament chemical vapor deposition technique is described. The resulting tungsten and tungsten oxide films were characterized using various techniques such as x-ray diffraction (XRD), Raman spectroscopy and Scanning electron microscopy (SEM). XRD results revealed the complete conversion of cubic phase of pure tungsten into monoclinic phase of tungsten oxide. Raman spectroscopic analysis also confirmed the formation of WO3. SEM images show considerable alteration in morphology from well faceted particles to wafers when pure W-film was converted to WO3 film. The wafer like morphology of WO3 films is found to be suitable for gas sensing towards hazardous gases such as NO2 and NH3. The WO3 films showcased their highly responsive nature towards NO2 gas with exceptionally high gas sensitivity ~32. WO3 film demonstrated longer recovery time towards NO2 gas unlike NH3 gas making them attractive for their utilization in ‘Newer application’ such as a catalyst support material in catalytic converter devices which are potential representatives to arrest pollutant gases (NO2) getting flown into the living environment.

  1. Oxidation of fluorinated amorphous carbon (a-CF(x)) films.

    PubMed

    Yun, Yang; Broitman, Esteban; Gellman, Andrew J

    2010-01-19

    Amorphous fluorinated carbon (a-CF(x)) films have a variety of potential technological applications. In most such applications these films are exposed to air and undergo partial surface oxidation. X-ray photoemission spectroscopy has been used to study the oxidation of fresh a-CF(x) films deposited by magnetron sputtering. The oxygen sticking coefficient measured by exposure to low pressures (<10(-3) Torr) of oxygen at room temperature is on the order of S approximately 10(-6), indicating that the surfaces of these films are relatively inert to oxidation when compared with most metals. The X-ray photoemission spectra indicate that the initial stages of oxygen exposure (<10(7) langmuirs) result in the preferential oxidation of the carbon atoms with zero or one fluorine atom, perhaps because these carbon atoms are more likely to be found in configurations with unsaturated double bonds and radicals than carbon atoms with two or three fluorine atoms. Exposure of the a-CF(x) film to atmospheric pressures of air (effective exposure of 10(12) langmuirs to O(2)) results in lower levels of oxygen uptake than the low pressure exposures (<10(7) langmuirs). It is suggested that this is the result of oxidative etching of the most reactive carbon atoms, leaving a relatively inert surface. Finally, low pressure exposures to air result in the adsorption of both nitrogen and oxygen onto the surface. Some of the nitrogen adsorbed on the surface at low pressures is in a reversibly adsorbed state in the sense that subsequent exposure to low pressures of O(2) results in the displacement of nitrogen by oxygen. Similarly, when an a-CF(x) film oxidized in pure O(2) is exposed to low pressures of air, some of the adsorbed oxygen is displaced by nitrogen. It is suggested that these forms of nitrogen and oxygen are bound to free radical sites in the film.

  2. Stress and phase transformation phenomena in oxide films

    SciTech Connect

    Exarhos, G.J.; Hess, N.J.

    1992-04-01

    In situ optical methods are reviewed for characterization of phase transformation processes and evaluation of residual stress in solution- deposited metastable oxide films. Such low density films most often are deposited as disordered phases making them prone to crystallization and attendant densification when subjected to increased temperature and/or applied pressure. Inherent stress imparted during film deposition and its evolution during the transformation are evaluated from phonon frequency shifts seen in Raman spectra (TiO{sub 2}) or from changes in the laser-induced fluorescence emission spectra for films containing rare earth (Sm{sup +3}:Y{sub 3}Al{sub 5}O{sub 12}) or transition metal (Cr{sup +3}:Al{sub 2}O{sub 3}) dopants. The data in combination with measured increases in line intensities intrinsic to the evolving phase are used to follow crystallization processes in thin films. In general, film deposition parameters are found to influence the crystallite ingrowth kinetics and the magnitude of stress and stress relaxation in the film during the transformation. The utility of these methods to probe crystallization phenomena in oxide films will be addressed.

  3. Growth control of the oxidation state in vanadium oxide thin films

    NASA Astrophysics Data System (ADS)

    Lee, Shinbuhm; Meyer, Tricia L.; Park, Sungkyun; Egami, Takeshi; Lee, Ho Nyung

    2014-12-01

    Precise control of the chemical valence or oxidation state of vanadium in vanadium oxide thin films is highly desirable for not only fundamental research but also technological applications that utilize the subtle change in the physical properties originating from the metal-insulator transition (MIT) near room temperature. However, due to the multivalent nature of vanadium and the lack of a good understanding on growth control of the oxidation state, stabilization of phase pure vanadium oxides with a single oxidation state is extremely challenging. Here, we systematically varied the growth conditions to clearly map out the growth window for preparing phase pure epitaxial vanadium oxides by pulsed laser deposition for providing a guideline to grow high quality thin films with well-defined oxidation states of V2 + 3 O 3 , V + 4 O 2 , and V2 + 5 O 5 . A well pronounced MIT was only observed in VO2 films grown in a very narrow range of oxygen partial pressure P(O2). The films grown either in lower (<10 mTorr) or higher P(O2) (>25 mTorr) result in V2O3 and V2O5 phases, respectively, thereby suppressing the MIT for both cases. We have also found that the resistivity ratio before and after the MIT of VO2 thin films can be further enhanced by one order of magnitude when the films are further oxidized by post-annealing at a well-controlled oxidizing ambient. This result indicates that stabilizing vanadium into a single valence state has to compromise with insufficient oxidation of an as grown thin film and, thereby, a subsequent oxidation is required for an improved MIT behavior.

  4. Growth control of the oxidation state in vanadium oxide thin films

    SciTech Connect

    Lee, Shinbuhm; Meyer, Tricia L.; Lee, Ho Nyung; Park, Sungkyun; Egami, Takeshi

    2014-12-01

    Precise control of the chemical valence or oxidation state of vanadium in vanadium oxide thin films is highly desirable for not only fundamental research but also technological applications that utilize the subtle change in the physical properties originating from the metal-insulator transition (MIT) near room temperature. However, due to the multivalent nature of vanadium and the lack of a good understanding on growth control of the oxidation state, stabilization of phase pure vanadium oxides with a single oxidation state is extremely challenging. Here, we systematically varied the growth conditions to clearly map out the growth window for preparing phase pure epitaxial vanadium oxides by pulsed laser deposition for providing a guideline to grow high quality thin films with well-defined oxidation states of V{sub 2}{sup +3}O{sub 3}, V{sup +4}O{sub 2}, and V{sub 2}{sup +5}O{sub 5}. A well pronounced MIT was only observed in VO{sub 2} films grown in a very narrow range of oxygen partial pressure P(O{sub 2}). The films grown either in lower (<10 mTorr) or higher P(O{sub 2}) (>25 mTorr) result in V{sub 2}O{sub 3} and V{sub 2}O{sub 5} phases, respectively, thereby suppressing the MIT for both cases. We have also found that the resistivity ratio before and after the MIT of VO{sub 2} thin films can be further enhanced by one order of magnitude when the films are further oxidized by post-annealing at a well-controlled oxidizing ambient. This result indicates that stabilizing vanadium into a single valence state has to compromise with insufficient oxidation of an as grown thin film and, thereby, a subsequent oxidation is required for an improved MIT behavior.

  5. Growth control of the oxidation state in vanadium oxide thin films

    SciTech Connect

    Lee, Shinbuhm; Meyer, Tricia L.; Park, Sungkyun; Lee, Ho Nyung

    2014-12-05

    Precise control of the chemical valence or oxidation state of vanadium in vanadium oxide thin films is highly desirable for not only fundamental research, but also technological applications that utilize the subtle change in the physical properties originating from the metalinsulator transition (MIT) near room temperature. However, due to the multivalent nature of vanadium and the lack of a good understanding on growth control of the oxidation state, stabilization of phase pure vanadium oxides with a single oxidation state is extremely challenging. Here, we systematically varied the growth conditions to clearly map out the growth window for preparing phase pure epitaxial vanadium oxides by pulsed laser deposition for providing a guideline to grow high quality thin films with well-defined oxidation states of V₂⁺²O₃, V⁺⁴O₂, and V₂⁺⁵O₅. A well pronounced MIT was only observed in VO₂ films grown in a very narrow range of oxygen partial pressure P(O₂). The films grown either in lower (< 10 mTorr) or higher P(O₂) (> 25 mTorr) result in V₂O₃ and V₂O₅ phases, respectively, thereby suppressing the MIT for both cases. We have also found that the resistivity ratio before and after the MIT of VO₂ thin films can be further enhanced by one order of magnitude when the films are further oxidized by post-annealing at a well-controlled oxidizing ambient. This result indicates that stabilizing vanadium into a single valence state has to compromise with insufficient oxidation of an as grown thin film and, thereby, a subsequent oxidation is required for an 3 improved MIT behavior.

  6. Growth control of the oxidation state in vanadium oxide thin films

    DOE PAGES

    Lee, Shinbuhm; Meyer, Tricia L.; Park, Sungkyun; ...

    2014-12-05

    Precise control of the chemical valence or oxidation state of vanadium in vanadium oxide thin films is highly desirable for not only fundamental research, but also technological applications that utilize the subtle change in the physical properties originating from the metalinsulator transition (MIT) near room temperature. However, due to the multivalent nature of vanadium and the lack of a good understanding on growth control of the oxidation state, stabilization of phase pure vanadium oxides with a single oxidation state is extremely challenging. Here, we systematically varied the growth conditions to clearly map out the growth window for preparing phase puremore » epitaxial vanadium oxides by pulsed laser deposition for providing a guideline to grow high quality thin films with well-defined oxidation states of V₂⁺²O₃, V⁺⁴O₂, and V₂⁺⁵O₅. A well pronounced MIT was only observed in VO₂ films grown in a very narrow range of oxygen partial pressure P(O₂). The films grown either in lower (< 10 mTorr) or higher P(O₂) (> 25 mTorr) result in V₂O₃ and V₂O₅ phases, respectively, thereby suppressing the MIT for both cases. We have also found that the resistivity ratio before and after the MIT of VO₂ thin films can be further enhanced by one order of magnitude when the films are further oxidized by post-annealing at a well-controlled oxidizing ambient. This result indicates that stabilizing vanadium into a single valence state has to compromise with insufficient oxidation of an as grown thin film and, thereby, a subsequent oxidation is required for an 3 improved MIT behavior.« less

  7. Corrosion Behavior of Aluminum Oxide Film Growth by Controlled Anodic Oxidation

    NASA Astrophysics Data System (ADS)

    Dumitrascu, V.; Benea, L.; Danaila, E.

    2017-06-01

    Due to the light weight and good corrosion resistance, nowadays aluminum and its alloys are used in different industries in order to decrease the maintenance costs and also to increase the equipments lifetime cycle. When aluminum and its alloys are exposed to the extreme environments, the native aluminum oxide film lose the anticorrosive properties that lead to the damage of equipments and increasing the costs. In order to improve the anticorrosive and mechanical performances of aluminum and its alloys, different techniques are used: organic coatings, the growth of a thick aluminum oxide film through different methods, etc. The most used method for aluminum oxide growth is anodic oxidation. Anodic oxidation is an electrochemical method that allows to growth an aluminum oxide film with controllable characteristics. The aim of present paper was to growth on 1050 aluminum alloy surface nanoporous aluminum oxide films with improved anticorrosive properties. The obtained nanoporous aluminum oxide films were characterized morphological and structural by scanning electron microscopy coupled with X-ray energy dispersive analyzer. The anticorrosive properties were evaluated by electrochemical methods such as: open circuit potential, electrochemical impedance spectroscopy and cyclic voltammetry. The results showed that anodic oxidation treatment improve the anticorrosive performances of 1050 aluminum alloy.

  8. Aerosol chemical vapor deposition of metal oxide films

    DOEpatents

    Ott, K.C.; Kodas, T.T.

    1994-01-11

    A process of preparing a film of a multicomponent metal oxide including: forming an aerosol from a solution comprised of a suitable solvent and at least two precursor compounds capable of volatilizing at temperatures lower than the decomposition temperature of said precursor compounds; passing said aerosol in combination with a suitable oxygen-containing carrier gas into a heated zone, said heated zone having a temperature sufficient to evaporate the solvent and volatilize said precursor compounds; and passing said volatilized precursor compounds against the surface of a substrate, said substrate having a sufficient temperature to decompose said volatilized precursor compounds whereby metal atoms contained within said volatilized precursor compounds are deposited as a metal oxide film upon the substrate is disclosed. In addition, a coated article comprising a multicomponent metal oxide film conforming to the surface of a substrate selected from the group consisting of silicon, magnesium oxide, yttrium-stabilized zirconium oxide, sapphire, or lanthanum gallate, said multicomponent metal oxide film characterized as having a substantially uniform thickness upon said substrate.

  9. Electrochromic behavior in CVD grown tungsten oxide films

    NASA Astrophysics Data System (ADS)

    Gogova, D.; Iossifova, A.; Ivanova, T.; Dimitrova, Zl; Gesheva, K.

    1999-03-01

    Solid state electrochemical devices (ECDs) for smart windows, large area displays and automobile rearview mirrors are of considerable technological and commercial interest. In this paper, we studied the electrochromic properties of amorphous and polycrystalline CVD carbonyl tungsten oxide films and the possibility for sol-gel thin TiO 2 film to play the role of passive electrode in an electrochromic window with solid polymer electrolyte.

  10. Graphene Oxide Transparent Hybrid Film and Its Ultraviolet Shielding Property.

    PubMed

    Xie, Siyuan; Zhao, Jianfeng; Zhang, Bowu; Wang, Ziqiang; Ma, Hongjuan; Yu, Chuhong; Yu, Ming; Li, Linfan; Li, Jingye

    2015-08-19

    Herein, we first reported a facile strategy to prepare functional Poly(vinyl alcohol) (PVA) hybrid film with well ultraviolet (UV) shielding property and visible light transmittance using graphene oxide nanosheets as UV-absorber. The absorbance of ultraviolet light at 300 nm can be up to 97.5%, while the transmittance of visible light at 500 nm keeps 40% plus. This hybrid film can protect protein from UVA light induced photosensitive damage, remarkably.

  11. Cadmium-Tin Oxide Transparent Conductive Thin Films

    NASA Astrophysics Data System (ADS)

    Stapinski, T.; Leja, E.; Marszalek, K.

    1986-09-01

    Cadmium-tin oxide (CTO) films have been prepared by d.c. reactive sputtering of Cd-Sn alloy targets in Ar-02 gas mixture. The electrical, optical and structural properties as well as the chemical composition of transparent conducting CTO films were found to depend on sputtering conditions. The value of optical band gap, optical constants, effective mass and relaxation time of electrons have been determined.

  12. Nitrogen doped zinc oxide thin film

    SciTech Connect

    Li, Sonny Xiao-zhe

    2003-01-01

    To summarize, polycrystalline ZnO thin films were grown by reactive sputtering. Nitrogen was introduced into the films by reactive sputtering in an NO2 plasma or by N+ implantation. All ZnO films grown show n-type conductivity. In unintentionally doped ZnO films, the n-type conductivities are attributed to Zni, a native shallow donor. In NO2-grown ZnO films, the n-type conductivity is attributed to (N2)O, a shallow double donor. In NO2-grown ZnO films, 0.3 atomic % nitrogen was found to exist in the form of N2O and N2. Upon annealing, N2O decomposes into N2 and O2. In furnace-annealed samples N2 redistributes diffusively and forms gaseous N2 bubbles in the films. Unintentionally doped ZnO films were grown at different oxygen partial pressures. Zni was found to form even at oxygen-rich condition and led to n-type conductivity. N+ implantation into unintentionally doped ZnO film deteriorates the crystallinity and optical properties and leads to higher electron concentration. The free electrons in the implanted films are attributed to the defects introduced by implantation and formation of (N2)O and Zni. Although today there is still no reliable means to produce good quality, stable p-type ZnO material, ZnO remains an attractive material with potential for high performance short wavelength optoelectronic devices. One may argue that gallium nitride was in a similar situation a decade ago. Although we did not obtain any p-type conductivity, we hope our research will provide a valuable reference to the literature.

  13. Anodic oxidation as a means to produce memristive films.

    PubMed

    Diamanti, Maria Vittoria; Pisoni, Riccardo; Cologni, Andrea; Brenna, Andrea; Corinto, Fernando; Pedeferri, MariaPia

    2016-07-26

    In the past few years there has been growing interest in memristive devices. These devices rely on thin metal oxide films with a peculiar structure and composition, making precise control of oxide features vital. To this end, anodic oxidation allows a very large range of oxides to be formed on the surface of valve metals, whose thickness, structure and functional properties depend on the process parameters introduced. This work reports how memristive anodic oxides were obtained on titanium and other valve metals, such as niobium and tantalum. Anodic oxidation was performed on valve metals by immersion in H2SO4 or H3PO4 electrolytes and application of voltages ranging from 10 to 90 V. The memristive behavior was evaluated by cyclic voltammetry. The behavior of differently grown oxides was compared to identify the best conditions to achieve good memristive performances. High voltages were identified as not suitable due to the excessive oxide thickness, while below 20 V the film was not thick and uniform enough to give a good response. Surface preparation also played a major role in the observation of memristive properties. Optimal surface preparation and anodizing conditions were seen to give high memristive perfomances on both titanium and niobium oxides, while on tantalum oxides no reproducibility was achieved.

  14. Investigation of solution-processed bismuth-niobium-oxide films

    SciTech Connect

    Inoue, Satoshi; Ariga, Tomoki; Matsumoto, Shin; Onoue, Masatoshi; Miyasako, Takaaki; Tokumitsu, Eisuke; Shimoda, Tatsuya; Chinone, Norimichi; Cho, Yasuo

    2014-10-21

    The characteristics of bismuth-niobium-oxide (BNO) films prepared using a solution process were investigated. The BNO film annealed at 550°C involving three phases: an amorphous phase, Bi₃NbO₇ fluorite microcrystals, and Nb-rich cubic pyrochlore microcrystals. The cubic pyrochlore structure, which was the main phase in this film, has not previously been reported in BNO films. The relative dielectric constant of the BNO film was approximately 140, which is much higher than that of a corresponding film prepared using a conventional vacuum sputtering process. Notably, the cubic pyrochlore microcrystals disappeared with increasing annealing temperature and were replaced with triclinic β-BiNbO₄ crystals at 590°C. The relative dielectric constant also decreased with increasing annealing temperature. Therefore, the high relative dielectric constant of the BNO film annealed at 550°C is thought to result from the BNO cubic pyrochlore structure. In addition, the BNO films annealed at 500°C contained approximately 6.5 atm.% carbon, which was lost at approximately 550°C. This result suggests that the carbon in the BNO film played an important role in the formation of the cubic pyrochlore structure.

  15. Melting of thin films of alkanes on magnesium oxide

    NASA Astrophysics Data System (ADS)

    Arnold, T.; Barbour, A.; Chanaa, S.; Cook, R. E.; Fernandez-Canato, D.; Landry, P.; Seydel, T.; Yaron, P.; Larese, J. Z.

    2009-02-01

    Recent incoherent neutron scattering investigations of the dynamics of thin alkane films adsorbed on the Magnesium Oxide (100) surface are reported. There are marked differences in the behaviour of these films, as a function of temperature and coverage, compared to similar measurements on graphite. In particular, it has previously been shown that adsorbed multilayer films on graphite exhibit an interfacial solid monolayer that coexists with bulk-like liquid, well above the bulk melting point. In contrast, these studies show that the alkane films on MgO exhibit no such stabilization of the solid layer closest to the substrate as a function of the film thickness, even though the monolayer crystal structures are remarkably similar. These studies are supported by extensive thermodynamic data, a growing body of structural data from neutron diffraction and state of the art computer modelling

  16. Enhanced optical constants of nanocrystalline yttrium oxide thin films

    SciTech Connect

    Ramana, C. V.; Mudavakkat, V. H.; Bharathi, K. Kamala; Atuchin, V. V.; Pokrovsky, L. D.; Kruchinin, V. N.

    2011-01-17

    Yttrium oxide (Y{sub 2}O{sub 3}) films with an average crystallite-size (L) ranging from 5 to 40 nm were grown by sputter-deposition onto Si(100) substrates. The optical properties of grown Y{sub 2}O{sub 3} films were evaluated using spectroscopic ellipsometry measurements. The size-effects were significant on the optical constants and their dispersion profiles of Y{sub 2}O{sub 3} films. A significant enhancement in the index of refraction (n) is observed in well-defined Y{sub 2}O{sub 3} nanocrystalline films compared to that of amorphous Y{sub 2}O{sub 3}. A direct, linear L-n relationship found for Y{sub 2}O{sub 3} films suggests that tuning optical properties for desired applications can be achieved by controlling the size at the nanoscale dimensions.

  17. Complex Oxide Thin Film Metamaterial Structures for THz applications

    NASA Astrophysics Data System (ADS)

    Shreiber, D.; Cravey, R.; Cole, M. W.

    2013-03-01

    Metamaterials operating in the frequency range of 0.1-1.5 THz are of a special interest for multiple Army applications such as communications, NDE of materials, and detection of chem./bio hazards. Recently proposed dielectric metamaterials present an intriguing venue for the developments in this field due to their low propagation losses and ease of fabrication. These dielectric metamaterials were implemented in bulk and in thick films. Tunability of ferroelectric complex oxides is achieved by applied bias voltage and constitutes an additional benefit for multiple applications. However, real-life applications require usage of relatively low bias voltage which is achievable only by using a ferroelectric complex oxide thin-film. Although the physical dimensions of the thin film metamaterial structures suggest their usage in IR-optical spectrum, their very high dielectric constant provides a rare opportunity to lower their resonant frequency to the frequency range of interest. This presentation will discuss the opportunities and challenges associated with the metamaterial complex oxide thin film structures including numerical investigations of the resonant frequency shift as a function of the complex oxide thin film dielectric constant and thickness.

  18. Review of solution-processed oxide thin-film transistors

    NASA Astrophysics Data System (ADS)

    Kim, Si Joon; Yoon, Seokhyun; Kim, Hyun Jae

    2014-02-01

    In this review, we summarize solution-processed oxide thin-film transistors (TFTs) researches based on our fulfillments. We describe the fundamental studies of precursor composition effects at the beginning in order to figure out the role of each component in oxide semiconductors, and then present low temperature process for the adoption of flexible devices. Moreover, channel engineering for high performance and reliability of solution-processed oxide TFTs and various coating methods: spin-coating, inkjet printing, and gravure printing are also presented. The last topic of this review is an overview of multi-functional solution-processed oxide TFTs for various applications such as photodetector, biosensor, and memory.

  19. Surface and sub-surface thermal oxidation of thin ruthenium films

    SciTech Connect

    Coloma Ribera, R.; Kruijs, R. W. E. van de; Yakshin, A. E.; Bijkerk, F.; Kokke, S.; Zoethout, E.

    2014-09-29

    A mixed 2D (film) and 3D (nano-column) growth of ruthenium oxide has been experimentally observed for thermally oxidized polycrystalline ruthenium thin films. Furthermore, in situ x-ray reflectivity upon annealing allowed the detection of 2D film growth as two separate layers consisting of low density and high density oxides. Nano-columns grow at the surface of the low density oxide layer, with the growth rate being limited by diffusion of ruthenium through the formed oxide film. Simultaneously, with the growth of the columns, sub-surface high density oxide continues to grow limited by diffusion of oxygen or ruthenium through the oxide film.

  20. Surface and sub-surface thermal oxidation of thin ruthenium films

    NASA Astrophysics Data System (ADS)

    Coloma Ribera, R.; van de Kruijs, R. W. E.; Kokke, S.; Zoethout, E.; Yakshin, A. E.; Bijkerk, F.

    2014-09-01

    A mixed 2D (film) and 3D (nano-column) growth of ruthenium oxide has been experimentally observed for thermally oxidized polycrystalline ruthenium thin films. Furthermore, in situ x-ray reflectivity upon annealing allowed the detection of 2D film growth as two separate layers consisting of low density and high density oxides. Nano-columns grow at the surface of the low density oxide layer, with the growth rate being limited by diffusion of ruthenium through the formed oxide film. Simultaneously, with the growth of the columns, sub-surface high density oxide continues to grow limited by diffusion of oxygen or ruthenium through the oxide film.

  1. Comparison of topotactic fluorination methods for complex oxide films

    SciTech Connect

    Moon, E. J. Choquette, A. K.; Huon, A.; Kulesa, S. Z.; May, S. J.; Barbash, D.

    2015-06-01

    We have investigated the synthesis of SrFeO{sub 3−α}F{sub γ} (α and γ ≤ 1) perovskite films using topotactic fluorination reactions utilizing poly(vinylidene fluoride) as a fluorine source. Two different fluorination methods, a spin-coating and a vapor transport approach, were performed on as-grown SrFeO{sub 2.5} films. We highlight differences in the structural, compositional, and optical properties of the oxyfluoride films obtained via the two methods, providing insight into how fluorination reactions can be used to modify electronic and optical behavior in complex oxide heterostructures.

  2. Annealing and oxidation of silicon oxide films prepared by plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Chen, X. Y.; Lu, Y. F.; Tang, L. J.; Wu, Y. H.; Cho, B. J.; Xu, X. J.; Dong, J. R.; Song, W. D.

    2005-01-01

    We have investigated phase separation, silicon nanocrystal (Si NC) formation and optical properties of Si oxide (SiOx, 0films by high-vacuum annealing and dry oxidation. The SiOx films were deposited by plasma-enhanced chemical vapor deposition at different nitrous-oxide/silane flow ratios. The physical and optical properties of the SiOx films were studied as a result of high-vacuum annealing and thermal oxidation. X-ray photoelectron spectroscopy (XPS) reveals that the as-deposited films have a random-bonding or continuous-random-network structure with different oxidation states. After annealing at temperatures above 1000 °C, the intermediate Si continuum in XPS spectra (referring to the suboxide) split to Si peaks corresponding to SiO2 and elemental Si. This change indicates the phase separation of the SiOx into more stable SiO2 and Si clusters. Raman, high-resolution transmission electron microscopy and optical absorption confirmed the phase separation and the formation of Si NCs in the films. The size of Si NCs increases with increasing Si concentration in the films and increasing annealing temperature. Two photoluminescence (PL) bands were observed in the films after annealing. The ultraviolet (UV)-range PL with a peak fixed at 370-380 nm is independent of Si concentration and annealing temperature, which is a characteristic of defect states. Strong PL in red range shows redshifts from ˜600 to 900 nm with increasing Si concentration and annealing temperature, which supports the quantum confinement model. After oxidation of the high-temperature annealed films, the UV PL was almost quenched while the red PL shows continuous blueshifts with increasing oxidation time. The different oxidation behaviors further relate the UV PL to the defect states and the red PL to the recombination of quantum-confined excitions.

  3. Ultraviolet-induced erasable photochromism in bilayer metal oxide films

    NASA Astrophysics Data System (ADS)

    Terakado, Nobuaki; Tanaka, Keiji; Nakazawa, Akira

    2011-09-01

    We demonstrate that the optical transmittance of bilayer samples consisting of pyrolytically coated amorphous Mg-Sn-O and metal oxide films such as In 2O 3 and SnO 2 decreases upon ultraviolet illumination, but can be recovered by annealing in air at ˜300 ∘C. Spectral, structural, and compositional studies suggest that this photochromic phenomenon is induced by photoelectronic excitation in the Mg-Sn-O film, electron injection into the metal oxide, which becomes negatively charged, and subsequent formation of metallic particles, which absorb and/or scatter visible light.

  4. Characterization of reliability of printed indium tin oxide thin films.

    PubMed

    Hong, Sung-Jei; Kim, Jong-Woong; Jung, Seung-Boo

    2013-11-01

    Recently, decreasing the amount of indium (In) element in the indium tin oxide (ITO) used for transparent conductive oxide (TCO) thin film has become necessary for cost reduction. One possible approach to this problem is using printed ITO thin film instead of sputtered. Previous studies showed potential for printed ITO thin films as the TCO layer. However, nothing has been reported on the reliability of printed ITO thin films. Therefore, in this study, the reliability of printed ITO thin films was characterized. ITO nanoparticle ink was fabricated and printed onto a glass substrate followed by heating at 400 degrees C. After measurement of the initial values of sheet resistance and optical transmittance of the printed ITO thin films, their reliabilities were characterized with an isothermal-isohumidity test for 500 hours at 85 degrees C and 85% RH, a thermal shock test for 1,000 cycles between 125 degrees C and -40 degrees C, and a high temperature storage test for 500 hours at 125 degrees C. The same properties were investigated after the tests. Printed ITO thin films showed stable properties despite extremely thermal and humid conditions. Sheet resistances of the printed ITO thin films changed slightly from 435 omega/square to 735 omega/square 507 omega/square and 442 omega/square after the tests, respectively. Optical transmittances of the printed ITO thin films were slightly changed from 84.74% to 81.86%, 88.03% and 88.26% after the tests, respectively. These test results suggest the stability of printed ITO thin film despite extreme environments.

  5. Magnetron sputtered nanostructured cadmium oxide films for ammonia sensing

    SciTech Connect

    Dhivya, P.; Prasad, A.K.; Sridharan, M.

    2014-06-01

    Nanostructured cadmium oxide (CdO) films were deposited on to glass substrates by reactive dc magnetron sputtering technique. The depositions were carried out for different deposition times in order to obtain films with varying thicknesses. The CdO films were polycrystalline in nature with cubic structure showing preferred orientation in (1 1 1) direction as observed by X-ray diffraction (XRD). Field-emission scanning electron microscope (FE-SEM) micrographs showed uniform distribution of grains of 30–35 nm size and change in morphology from spherical to elliptical structures upon increasing the film thickness. The optical band gap value of the CdO films decreased from 2.67 to 2.36 eV with increase in the thickness. CdO films were deposited on to interdigitated electrodes to be employed as ammonia (NH{sub 3}) gas sensor. The fabricated CdO sensor with thickness of 294 nm has a capacity to detect NH{sub 3} as low as 50 ppm at a relatively low operating temperature of 150 °C with quick response and recovery time. - Highlights: • Nanostructured CdO films were deposited on to glass substrates using magnetron sputtering. • Deposition time was varied in order to obtain films with different thicknesses. • The CdO films were polycrystalline in nature with preferred orientation along (1 1 1) direction. • The optical bandgap values of the films decreased on increasing the thickness of the films. • CdO films with different thickness such as 122, 204, 294 nm was capable to detect NH{sub 3} down to 50 ppm at operating temperature of 150 °C.

  6. Ligand field effect at oxide-metal interface on the chemical reactivity of ultrathin oxide film surface.

    PubMed

    Jung, Jaehoon; Shin, Hyung-Joon; Kim, Yousoo; Kawai, Maki

    2012-06-27

    Ultrathin oxide film is currently one of the paramount candidates for a heterogeneous catalyst because it provides an additional dimension, i.e., film thickness, to control chemical reactivity. Here, we demonstrate that the chemical reactivity of ultrathin MgO film grown on Ag(100) substrate for the dissociation of individual water molecules can be systematically controlled by interface dopants over the film thickness. Density functional theory calculations revealed that adhesion at the oxide-metal interface can be addressed by the ligand field effect and is linearly correlated with the chemical reactivity of the oxide film. In addition, our results indicate that the concentration of dopant at the interface can be controlled by tuning the drawing effect of oxide film. Our study provides not only profound insight into chemical reactivity control of ultrathin oxide film supported by a metal substrate but also an impetus for investigating ultrathin oxide films for a wider range of applications.

  7. Plasma enhanced chemical vapor deposition (PECVD) method of forming vanadium oxide films and vanadium oxide thin-films prepared thereby

    DOEpatents

    Zhang, Ji-Guang; Tracy, C. Edwin; Benson, David K.; Turner, John A.; Liu, Ping

    2000-01-01

    A method is disclosed of forming a vanadium oxide film on a substrate utilizing plasma enhanced chemical vapor deposition. The method includes positioning a substrate within a plasma reaction chamber and then forming a precursor gas comprised of a vanadium-containing chloride gas in an inert carrier gas. This precursor gas is then mixed with selected amounts of hydrogen and oxygen and directed into the reaction chamber. The amounts of precursor gas, oxygen and hydrogen are selected to optimize the final properties of the vanadium oxide film An rf plasma is generated within the reaction chamber to chemically react the precursor gas with the hydrogen and the oxygen to cause deposition of a vanadium oxide film on the substrate while the chamber deposition pressure is maintained at about one torr or less. Finally, the byproduct gases are removed from the plasma reaction chamber.

  8. Breakdown mechanism in buried silicon oxide films

    NASA Astrophysics Data System (ADS)

    Mayo, Santos; Suehle, John S.; Roitman, Peter

    1993-09-01

    Charge injection leading to catastrophic breakdown has been used to study the dielectric properties of the buried oxide layer in silicon implanted with high-energy oxygen ions. Current versus gate bias, current versus time, and capacitance versus gate bias were used to characterize, at various temperatures, MOS metal-oxide-semiconductor capacitors with areas in the 1×10-4-1×10-2 cm2 range fabricated with commercially available single- or triple-implant separation by implanted oxygen silicon wafers. The data show that injected charge accumulates in the buried oxide at donorlike oxide traps ultimately leading to catastrophic breakdown. Both Poole-Frenkel and Fowler-Nordheim conduction, as well as impact-ionization mechanisms, have been identified in the oxide. The charge and field to breakdown in the best buried oxides are, respectively, near 1 C cm-2 and 10 MV cm-1, similar to the thermally grown oxide parameters. Cumulative distributions of these parameters measured over a large number of capacitors show that the frequency of breakdown events caused by extrinsic defects is scaled with the capacitor area. Intrinsic and extrinsic defect distributions are broader than with thermally grown oxides.

  9. Oxidized film structure and method of making epitaxial metal oxide structure

    DOEpatents

    Gan, Shupan [Richland, WA; Liang, Yong [Richland, WA

    2003-02-25

    A stable oxidized structure and an improved method of making such a structure, including an improved method of making an interfacial template for growing a crystalline metal oxide structure, are disclosed. The improved method comprises the steps of providing a substrate with a clean surface and depositing a metal on the surface at a high temperature under a vacuum to form a metal-substrate compound layer on the surface with a thickness of less than one monolayer. The compound layer is then oxidized by exposing the compound layer to essentially oxygen at a low partial pressure and low temperature. The method may further comprise the step of annealing the surface while under a vacuum to further stabilize the oxidized film structure. A crystalline metal oxide structure may be subsequently epitaxially grown by using the oxidized film structure as an interfacial template and depositing on the interfacial template at least one layer of a crystalline metal oxide.

  10. Manganese oxide nanowires, films, and membranes and methods of making

    DOEpatents

    Suib, Steven Lawrence [Storrs, CT; Yuan, Jikang [Storrs, CT

    2011-02-15

    Nanowires, films, and membranes comprising ordered porous manganese oxide-based octahedral molecular sieves and methods of making the same are disclosed. A method for forming nanowires includes hydrothermally treating a chemical precursor composition in a hydrothermal treating solvent to form the nanowires, wherein the chemical precursor composition comprises a source of manganese cations and a source of counter cations, and wherein the nanowires comprise ordered porous manganese oxide-based octahedral molecular sieves.

  11. Oxidative chemical vapor deposition of polyaniline thin films.

    PubMed

    Smolin, Yuriy Y; Soroush, Masoud; Lau, Kenneth K S

    2017-01-01

    Polyaniline (PANI) is synthesized via oxidative chemical vapor deposition (oCVD) using aniline as monomer and antimony pentachloride as oxidant. Microscopy and spectroscopy indicate that oCVD processing conditions influence the PANI film chemistry, oxidation, and doping level. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) indicate that a substrate temperature of 90 °C is needed to minimize the formation of oligomers during polymerization. Lower substrate temperatures, such as 25 °C, lead to a film that mostly includes oligomers. Increasing the oxidant flowrate to nearly match the monomer flowrate favors the deposition of PANI in the emeraldine state, and varying the oxidant flowrate can directly influence the oxidation state of PANI. Changing the reactor pressure from 700 to 35 mTorr does not have a significant effect on the deposited film chemistry, indicating that the oCVD PANI process is not concentration dependent. This work shows that oCVD can be used for depositing PANI and for effectively controlling the chemical state of PANI.

  12. Nanocolumnar Crystalline Vanadium Oxide-Molybdenum Oxide Antireflective Smart Thin Films with Superior Nanomechanical Properties.

    PubMed

    Dey, Arjun; Nayak, Manish Kumar; Esther, A Carmel Mary; Pradeepkumar, Maurya Sandeep; Porwal, Deeksha; Gupta, A K; Bera, Parthasarathi; Barshilia, Harish C; Mukhopadhyay, Anoop Kumar; Pandey, Ajoy Kumar; Khan, Kallol; Bhattacharya, Manjima; Kumar, D Raghavendra; Sridhara, N; Sharma, Anand Kumar

    2016-11-17

    Vanadium oxide-molybdenum oxide (VO-MO) thin (21-475 nm) films were grown on quartz and silicon substrates by pulsed RF magnetron sputtering technique by altering the RF power from 100 to 600 W. Crystalline VO-MO thin films showed the mixed phases of vanadium oxides e.g., V2O5, V2O3 and VO2 along with MoO3. Reversible or smart transition was found to occur just above the room temperature i.e., at ~45-50 °C. The VO-MO films deposited on quartz showed a gradual decrease in transmittance with increase in film thickness. But, the VO-MO films on silicon exhibited reflectance that was significantly lower than that of the substrate. Further, the effect of low temperature (i.e., 100 °C) vacuum (10(-5) mbar) annealing on optical properties e.g., solar absorptance, transmittance and reflectance as well as the optical constants e.g., optical band gap, refractive index and extinction coefficient were studied. Sheet resistance, oxidation state and nanomechanical properties e.g., nanohardness and elastic modulus of the VO-MO thin films were also investigated in as-deposited condition as well as after the vacuum annealing treatment. Finally, the combination of the nanoindentation technique and the finite element modeling (FEM) was employed to investigate yield stress and von Mises stress distribution of the VO-MO thin films.

  13. Nanocolumnar Crystalline Vanadium Oxide-Molybdenum Oxide Antireflective Smart Thin Films with Superior Nanomechanical Properties

    PubMed Central

    Dey, Arjun; Nayak, Manish Kumar; Esther, A. Carmel Mary; Pradeepkumar, Maurya Sandeep; Porwal, Deeksha; Gupta, A. K.; Bera, Parthasarathi; Barshilia, Harish C.; Mukhopadhyay, Anoop Kumar; Pandey, Ajoy Kumar; Khan, Kallol; Bhattacharya, Manjima; Kumar, D. Raghavendra; Sridhara, N.; Sharma, Anand Kumar

    2016-01-01

    Vanadium oxide-molybdenum oxide (VO-MO) thin (21–475 nm) films were grown on quartz and silicon substrates by pulsed RF magnetron sputtering technique by altering the RF power from 100 to 600 W. Crystalline VO-MO thin films showed the mixed phases of vanadium oxides e.g., V2O5, V2O3 and VO2 along with MoO3. Reversible or smart transition was found to occur just above the room temperature i.e., at ~45–50 °C. The VO-MO films deposited on quartz showed a gradual decrease in transmittance with increase in film thickness. But, the VO-MO films on silicon exhibited reflectance that was significantly lower than that of the substrate. Further, the effect of low temperature (i.e., 100 °C) vacuum (10−5 mbar) annealing on optical properties e.g., solar absorptance, transmittance and reflectance as well as the optical constants e.g., optical band gap, refractive index and extinction coefficient were studied. Sheet resistance, oxidation state and nanomechanical properties e.g., nanohardness and elastic modulus of the VO-MO thin films were also investigated in as-deposited condition as well as after the vacuum annealing treatment. Finally, the combination of the nanoindentation technique and the finite element modeling (FEM) was employed to investigate yield stress and von Mises stress distribution of the VO-MO thin films. PMID:27853234

  14. Nanocolumnar Crystalline Vanadium Oxide-Molybdenum Oxide Antireflective Smart Thin Films with Superior Nanomechanical Properties

    NASA Astrophysics Data System (ADS)

    Dey, Arjun; Nayak, Manish Kumar; Esther, A. Carmel Mary; Pradeepkumar, Maurya Sandeep; Porwal, Deeksha; Gupta, A. K.; Bera, Parthasarathi; Barshilia, Harish C.; Mukhopadhyay, Anoop Kumar; Pandey, Ajoy Kumar; Khan, Kallol; Bhattacharya, Manjima; Kumar, D. Raghavendra; Sridhara, N.; Sharma, Anand Kumar

    2016-11-01

    Vanadium oxide-molybdenum oxide (VO-MO) thin (21–475 nm) films were grown on quartz and silicon substrates by pulsed RF magnetron sputtering technique by altering the RF power from 100 to 600 W. Crystalline VO-MO thin films showed the mixed phases of vanadium oxides e.g., V2O5, V2O3 and VO2 along with MoO3. Reversible or smart transition was found to occur just above the room temperature i.e., at ~45–50 °C. The VO-MO films deposited on quartz showed a gradual decrease in transmittance with increase in film thickness. But, the VO-MO films on silicon exhibited reflectance that was significantly lower than that of the substrate. Further, the effect of low temperature (i.e., 100 °C) vacuum (10‑5 mbar) annealing on optical properties e.g., solar absorptance, transmittance and reflectance as well as the optical constants e.g., optical band gap, refractive index and extinction coefficient were studied. Sheet resistance, oxidation state and nanomechanical properties e.g., nanohardness and elastic modulus of the VO-MO thin films were also investigated in as-deposited condition as well as after the vacuum annealing treatment. Finally, the combination of the nanoindentation technique and the finite element modeling (FEM) was employed to investigate yield stress and von Mises stress distribution of the VO-MO thin films.

  15. Growth of ultrathin vanadium oxide films on Ag(100)

    NASA Astrophysics Data System (ADS)

    Nakamura, Takuya; Sugizaki, Yuichi; Ishida, Shuhei; Edamoto, Kazuyuki; Ozawa, Kenichi

    2016-07-01

    Vanadium oxide films were grown on Ag(100) by vanadium deposition in O2 and subsequent annealing at 450 °C. It was found that at least three types of ordered V oxide films, which showed (1 × 1), hexagonal, and (4 × 1) LEED patterns, were formed on Ag(100) depending on the O2 pressure during deposition and conditions during postannealing. The films with the hexagonal and (1 × 1) periodicities were characterized by photoelectron spectroscopy (PES) and near-edge X-ray absorption fine structure (NEXAFS) analysis. The film with the (1 × 1) periodicity was ascribed to a VO(100) film. On the other hand, the film with the hexagonal periodicity was found to be composed of V2O3, and the analysis of the LEED pattern revealed that the lattice parameter of the hexagonal lattice is 0.50 nm, which is very close to that of corundum V2O3(0001) (0.495 nm).

  16. Lubrication with Naturally Occurring Double Oxide Films

    DTIC Science & Technology

    1982-11-10

    rhenates, molybdates, vanadates , borates, osinoniates, and chromates. F;’iction tests were run over the temperature range 26 to 650C with single oxides...oxide properties the following compounds were chosen for evaluation: rhenates, osmoniates, molybdates, vanadates , borates, and chromates. Sliding...certain low melting point metals such as lead, bismuth , antimony, etc., cannot be used since they would seriously reduce the strength of the alloy

  17. Neutron Detection Utilizing Gadolinium Doped Hafnium Oxide Films

    DTIC Science & Technology

    2008-03-01

    emit low energy gamma rays, alpha particles, and neutron radiation . Many instruments capable of gamma detection have been available for decades...neutron detection because its interaction with neutrons creates fast electrons and gamma rays. Therefore, background gamma radiation causes a more...NEUTRON DETECTION UTILIZING GADOLINIUM DOPED HAFNIUM OXIDE FILMS THESIS Bryan D. Blasy, 2Lt

  18. Trends in the thermodynamic stability of ultrathin supported oxide films

    DOE PAGES

    Plessow, Philipp N.; Bajdich, Michal; Greene, Joshua; ...

    2016-05-05

    The formation of thin oxide films on metal supports is an important phenomenon, especially in the context of strong metal support interaction (SMSI). Computational predictions of the stability of these films are hampered by their structural complexity and a varying lattice mismatch with different supports. In this study, we report a large combination of supports and ultrathin oxide films studied with density functional theory (DFT). Trends in stability are investigated through a descriptor-based analysis. Since the studied films are bound to the support exclusively through metal–metal interaction, the adsorption energy of the oxide-constituting metal atom can be expected to bemore » a reasonable descriptor for the stability of the overlayers. If the same supercell is used for all supports, the overlayers experience different amounts of stress. Using supercells with small lattice mismatch for each system leads to significantly improved scaling relations for the stability of the overlayers. Finally, this approach works well for the studied systems and therefore allows the descriptor-based exploration of the thermodynamic stability of supported thin oxide layers.« less

  19. Trends in the thermodynamic stability of ultrathin supported oxide films

    SciTech Connect

    Plessow, Philipp N.; Bajdich, Michal; Greene, Joshua; Vojvodic, Aleksandra; Abild-Pedersen, Frank

    2016-05-05

    The formation of thin oxide films on metal supports is an important phenomenon, especially in the context of strong metal support interaction (SMSI). Computational predictions of the stability of these films are hampered by their structural complexity and a varying lattice mismatch with different supports. In this study, we report a large combination of supports and ultrathin oxide films studied with density functional theory (DFT). Trends in stability are investigated through a descriptor-based analysis. Since the studied films are bound to the support exclusively through metal–metal interaction, the adsorption energy of the oxide-constituting metal atom can be expected to be a reasonable descriptor for the stability of the overlayers. If the same supercell is used for all supports, the overlayers experience different amounts of stress. Using supercells with small lattice mismatch for each system leads to significantly improved scaling relations for the stability of the overlayers. Finally, this approach works well for the studied systems and therefore allows the descriptor-based exploration of the thermodynamic stability of supported thin oxide layers.

  20. Magnetic Transparent Conducting Oxide Film And Method Of Making

    DOEpatents

    Windisch, Jr., Charles F.; Exarhos, Gregory J.; Sharma, Shiv K.

    2006-03-14

    Cobalt-nickel oxide films of nominal 100 nm thickness, and resistivity as low as 0.06 O·cm have been deposited by spin-casting from both aqueous and organic precursor solutions followed by annealing at 450° C. in air. An increase in film resistivity was found upon substitution of other cations (e.g., Zn2+, Al3+) for Ni in the spinel structure. However, some improvement in the mechanical properties of the films resulted. On the other hand, addition of small amounts of Li decreased the resistivity. A combination of XRD, XPS, UV/Vis and Raman spectroscopy indicated that NiCo2O4 is the primary conducting component and that the conductivity reaches a maximum at this stoichiometry. When x<0.67, NiO forms leading to an increase in resistivity; when x>0.67, the oxide was all spinel but the increased Co content lowered the conductivity.

  1. Multiferroic oxide thin films and heterostructures

    NASA Astrophysics Data System (ADS)

    Lu, Chengliang; Hu, Weijin; Tian, Yufeng; Wu, Tom

    2015-06-01

    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.

  2. Multiferroic oxide thin films and heterostructures

    SciTech Connect

    Lu, Chengliang E-mail: Tao.Wu@kaust.edu.sa; Hu, Weijin; Wu, Tom E-mail: Tao.Wu@kaust.edu.sa; Tian, Yufeng

    2015-06-15

    Multiferroic materials promise a tantalizing perspective of novel applications in next-generation electronic, memory, and energy harvesting technologies, and at the same time they also represent a grand scientific challenge on understanding complex solid state systems with strong correlations between multiple degrees of freedom. In this review, we highlight the opportunities and obstacles in growing multiferroic thin films with chemical and structural integrity and integrating them in functional devices. Besides the magnetoelectric effect, multiferroics exhibit excellent resistant switching and photovoltaic properties, and there are plenty opportunities for them to integrate with other ferromagnetic and superconducting materials. The challenges include, but not limited, defect-related leakage in thin films, weak magnetism, and poor control on interface coupling. Although our focuses are Bi-based perovskites and rare earth manganites, the insights are also applicable to other multiferroic materials. We will also review some examples of multiferroic applications in spintronics, memory, and photovoltaic devices.

  3. Perovskite Oxide Thin Film Growth, Characterization, and Stability

    NASA Astrophysics Data System (ADS)

    Izumi, Andrew

    Studies into a class of materials known as complex oxides have evoked a great deal of interest due to their unique magnetic, ferroelectric, and superconducting properties. In particular, materials with the ABO3 perovskite structure have highly tunable properties because of the high stability of the structure, which allows for large scale doping and strain. This also allows for a large selection of A and B cations and valences, which can further modify the material's electronic structure. Additionally, deposition of these materials as thin films and superlattices through techniques such as pulsed laser deposition (PLD) results in novel properties due to the reduced dimensionality of the material. The novel properties of perovskite oxide heterostructures can be traced to a several sources, including chemical intermixing, strain and defect formation, and electronic reconstruction. The correlations between microstructure and physical properties must be investigated by examining the physical and electronic structure of perovskites in order to understand this class of materials. Some perovskites can undergo phase changes due to temperature, electrical fields, and magnetic fields. In this work we investigated Nd0.5Sr 0.5MnO3 (NSMO), which undergoes a first order magnetic and electronic transition at T=158K in bulk form. Above this temperature NSMO is a ferromagnetic metal, but transitions into an antiferromagnetic insulator as the temperature is decreased. This rapid transition has interesting potential in memory devices. However, when NSMO is deposited on (001)-oriented SrTiO 3 (STO) or (001)-oriented (LaAlO3)0.3-(Sr 2AlTaO6)0.7 (LSAT) substrates, this transition is lost. It has been reported in the literature that depositing NSMO on (110)-oriented STO allows for the transition to reemerge due to the partial epitaxial growth, where the NSMO film is strained along the [001] surface axis and partially relaxed along the [11¯0] surface axis. This allows the NSMO film enough

  4. Work function recovery of air exposed molybdenum oxide thin films

    NASA Astrophysics Data System (ADS)

    Irfan, Irfan; James Turinske, Alexander; Bao, Zhenan; Gao, Yongli

    2012-08-01

    We report substantial work function (WF) recovery of air exposed molybdenum oxide thin films with vacuum annealing. We observed a sharp reduction in the MoOx WF (from 6.8 eV to 5.6 eV) as well as a very thin layer of oxygen rich adsorbate on the MoOx film after an hour of air exposure. The WF of the exposed MoOx film started to gradually recover with increasing annealing temperature in vacuum, and the saturation in the WF recovery was observed at 450 °C with WF ˜6.4 eV. We further studied the interface formation between the annealed MoOx and copper phthalocyanine (CuPc). The highest occupied molecular orbital (HOMO) level of CuPc was observed to be almost pinned to the Fermi level, strongly suggesting the possibility of efficient hole injection with the vacuum annealed MoOx film.

  5. Structure of silicon oxide films prepared by vacuum deposition

    NASA Astrophysics Data System (ADS)

    Saito, Yoshio; Kaito, Chihiro; Nishio, Kenzo; Naiki, Toshio

    1985-05-01

    The structure of thin silicon oxide films 5 nm in thickness, which were prepared by electron beam evaporation of SiO 2 glass onto a NaCl substrate, has been examined by high resolution electron microscopy and diffraction. Although the films which were prepared with substrate temperatures ranging from room up to 400°C gave rise to amorphous haloes, lattice fringes in areas 1-2 nm in extent were, however, seen in the micrographs. It is shown that the film is composed of α-quartz micro-crystallites. Crystals of α-cristobalite with sizes of several tens of nanometers appeared at a substrate temperature of 500°C. At a substrate temperature of 600°C, β-cristobalite crystals with sizes of several tens of nanometers appeared. The structural changes due to the substrate temperature were attributed to incorporation of sodium atoms from the substrate into the SiO 2 film.

  6. Indium oxide inverse opal films synthesized by structure replication method

    NASA Astrophysics Data System (ADS)

    Amrehn, Sabrina; Berghoff, Daniel; Nikitin, Andreas; Reichelt, Matthias; Wu, Xia; Meier, Torsten; Wagner, Thorsten

    2016-04-01

    We present the synthesis of indium oxide (In2O3) inverse opal films with photonic stop bands in the visible range by a structure replication method. Artificial opal films made of poly(methyl methacrylate) (PMMA) spheres are utilized as template. The opal films are deposited via sedimentation facilitated by ultrasonication, and then impregnated by indium nitrate solution, which is thermally converted to In2O3 after drying. The quality of the resulting inverse opal film depends on many parameters; in this study the water content of the indium nitrate/PMMA composite after drying is investigated. Comparison of the reflectance spectra recorded by vis-spectroscopy with simulated data shows a good agreement between the peak position and calculated stop band positions for the inverse opals. This synthesis is less complex and highly efficient compared to most other techniques and is suitable for use in many applications.

  7. Structural transformation of nickel hydroxide films during anodic oxidation

    SciTech Connect

    Crocker, Robert W.; Muller, Rolf H.

    1992-05-01

    The transformation of anodically formed nickel hydroxide/oxy-hydroxide electrodes has been investigated. A mechanism is proposed for the anodic oxidation reaction, in which the reaction interface between the reduced and oxidized phases of the electrode evolves in a nodular topography that leads to inefficient utilization of the active electrode material. In the proposed nodular transformation model for the anodic oxidation reaction, nickel hydroxide is oxidized to nickel oxy-hydroxide in the region near the metal substrate. Since the nickel oxy-hydroxide is considerably more conductive than the surrounding nickel hydroxide, as further oxidation occurs, nodular features grow rapidly to the film/electrolyte interface. Upon emerging at the electrolyte interface, the reaction boundary between the nickel hydroxide and oxy-hydroxide phases spreads laterally across the film/electrolyte interface, creating an overlayer of nickel oxy-hydroxide and trapping uncharged regions of nickel hydroxide within the film. The nickel oxy-hydroxide overlayer surface facilitates the oxygen evolution side reaction. Scanning tunneling microscopy of the electrode in its charged state revealed evidence of 80 - 100 Angstrom nickel oxy-hydroxide nodules in the nickel hydroxide film. In situ spectroscopic ellipsometer measurements of films held at various constant potentials agree quantitatively with optical models appropriate to the nodular growth and subsequent overgrowth of the nickel oxy-hydroxide phase. A two-dimensional, numerical finite difference model was developed to simulate the current distribution along the phase boundary between the charged and uncharged material. The model was used to explore the effects of the physical parameters that govern the electrode behavior. The ratio of the conductivities of the nickel hydroxide and oxy-hydroxide phases was found to be the dominant parameter in the system.

  8. Structural transformation of nickel hydroxide films during anodic oxidation

    SciTech Connect

    Crocker, R.W.; Muller, R.H.

    1992-05-01

    The transformation of anodically formed nickel hydroxide/oxy-hydroxide electrodes has been investigated. A mechanism is proposed for the anodic oxidation reaction, in which the reaction interface between the reduced and oxidized phases of the electrode evolves in a nodular topography that leads to inefficient utilization of the active electrode material. In the proposed nodular transformation model for the anodic oxidation reaction, nickel hydroxide is oxidized to nickel oxy-hydroxide in the region near the metal substrate. Since the nickel oxy-hydroxide is considerably more conductive than the surrounding nickel hydroxide, as further oxidation occurs, nodular features grow rapidly to the film/electrolyte interface. Upon emerging at the electrolyte interface, the reaction boundary between the nickel hydroxide and oxy-hydroxide phases spreads laterally across the film/electrolyte interface, creating an overlayer of nickel oxy-hydroxide and trapping uncharged regions of nickel hydroxide within the film. The nickel oxy-hydroxide overlayer surface facilitates the oxygen evolution side reaction. Scanning tunneling microscopy of the electrode in its charged state revealed evidence of 80 {endash} 100 Angstrom nickel oxy-hydroxide nodules in the nickel hydroxide film. In situ spectroscopic ellipsometer measurements of films held at various constant potentials agree quantitatively with optical models appropriate to the nodular growth and subsequent overgrowth of the nickel oxy-hydroxide phase. A two-dimensional, numerical finite difference model was developed to simulate the current distribution along the phase boundary between the charged and uncharged material. The model was used to explore the effects of the physical parameters that govern the electrode behavior. The ratio of the conductivities of the nickel hydroxide and oxy-hydroxide phases was found to be the dominant parameter in the system.

  9. Polymer-assisted deposition of metal-oxide films.

    PubMed

    Jia, Q X; McCleskey, T M; Burrell, A K; Lin, Y; Collis, G E; Wang, H; Li, A D Q; Foltyn, S R

    2004-08-01

    Metal oxides are emerging as important materials for their versatile properties such as high-temperature superconductivity, ferroelectricity, ferromagnetism, piezoelectricity and semiconductivity. Metal-oxide films are conventionally grown by physical and chemical vapour deposition. However, the high cost of necessary equipment and restriction of coatings on a relatively small area have limited their potential applications. Chemical-solution depositions such as sol-gel are more cost-effective, but many metal oxides cannot be deposited and the control of stoichiometry is not always possible owing to differences in chemical reactivity among the metals. Here we report a novel process to grow metal-oxide films in large areas at low cost using polymer-assisted deposition (PAD), where the polymer controls the viscosity and binds metal ions, resulting in a homogeneous distribution of metal precursors in the solution and the formation of uniform metal-organic films. The latter feature makes it possible to grow simple and complex crack-free epitaxial metal-oxides.

  10. Electrical properties of films of zinc oxide nanoparticles and its hybrid with reduced graphene oxide

    SciTech Connect

    Madhuri, K. Priya; Bramhaiah, K.; John, Neena S.

    2016-05-23

    Free-standing films of ZnO nanoparticles (NPs) and reduced graphene oxide (rGO)-ZnO NPs hybrid are prepared at a liquid/liquid interface. The films are characterized by UV-visible spectroscopy, X-ray diffraction, scanning electron microscopy and atomic force microscopy. ZnO film consists of spherical aggregated NPs while the hybrid film contains folded sheets of rGO with embedded ZnO NPs. Electrical properties of the films and its photoresponse in presence of UV radiation are investigated using current sensing atomic force microscopy (CSAFM) at nanoscale and bulk measurements using two probe methods. Enhancement in photocurrent is observed in both cases and the current imaging reveals an inhomogeneous contribution by different ZnO grains in the film.

  11. Development of metal oxide impregnated stilbite thick film ethanol sensor

    NASA Astrophysics Data System (ADS)

    Mahabole, M. P.; Lakhane, M. A.; Choudhari, A. L.; Khairnar, R. S.

    2016-05-01

    This paper presents the study of the sensing efficiency of Titanium oxide/ Stilbite and Copper oxide /Stilbite composites towards detection of hazardous pollutants like ethanol. Stilbite based composites are prepared by physically mixing zeolite with metal oxides namely TiO2 and CuO with weight ratios of 25:75, 50:50 and 75:25. The resulting sensor materials are characterized by X-ray diffraction and Fourier Transform Infrared Spectroscopy techniques. Composite sensors are fabricated in the form of thick film by using screen printing technique. The effect of metal oxide concentration on various ethanol sensing parameters such as operating temperature, maximum uptake capacity and response/recovery time are investigated. The results indicate that metal oxide impregnated stilbite composites have great potential as low temperature ethanol sensor.

  12. Development of metal oxide impregnated stilbite thick film ethanol sensor

    SciTech Connect

    Mahabole, M. P. Lakhane, M. A.; Choudhari, A. L.; Khairnar, R. S.

    2016-05-06

    This paper presents the study of the sensing efficiency of Titanium oxide/ Stilbite and Copper oxide /Stilbite composites towards detection of hazardous pollutants like ethanol. Stilbite based composites are prepared by physically mixing zeolite with metal oxides namely TiO{sub 2} and CuO with weight ratios of 25:75, 50:50 and 75:25. The resulting sensor materials are characterized by X-ray diffraction and Fourier Transform Infrared Spectroscopy techniques. Composite sensors are fabricated in the form of thick film by using screen printing technique. The effect of metal oxide concentration on various ethanol sensing parameters such as operating temperature, maximum uptake capacity and response/recovery time are investigated. The results indicate that metal oxide impregnated stilbite composites have great potential as low temperature ethanol sensor.

  13. Preparation and aging of sputtered tungstic oxide films

    SciTech Connect

    Akram, H.; Tatsuoka, H.; Kitao, M.; Yamada, S.

    1987-09-01

    Conditions for the preparation of electrochromic tungstic oxide films with high efficiency for coloration have been investigated. Tungstic oxide films were deposited on glass substrates by rf sputtering in Ar-O/sub 2/ mixture from a compressed powder WO/sub 3/ target. As-deposited films require an ''aging process,'' in which the density of charges extracted in bleaching is smaller than that injected in coloring. It is considered that a part of the protons introduced during the aging combine with bonds of unstable oxygen contained in the as-deposited films. After the aging period, sputtered films have reversible coloration and bleaching cycles. Maximum electrochromic coloration efficiencies are 0.09 and 0.04 cm/sup 2//mC at wavelengths of 800 and 500 nm, respectively. They are obtained when the sputtering atmosphere is 0.04--0.05-Torr total pressure and 5% oxygen content. At any rate, substrate temperature should be kept at 100 /sup 0/C or less.

  14. Ln polyoxocations: yttrium oxide solution speciation & solution deposited thin films.

    PubMed

    Marsh, David A; Goberna-Ferrón, Sara; Baumeister, Mary K; Zakharov, Lev N; Nyman, May; Johnson, Darren W

    2017-01-17

    Rare earth oxide materials, including thin film coatings, are critically important in magnetic, luminescent and microelectric devices, and few substitutes have been discovered with comparable performance. Thin film coatings from solution are almost unknown for rare earth oxides, likely due to their high activity towards hydrolysis which yields poor quality thin films. The hexamer [Ln6(O)(OH)8(H2O)12(NO3)6](2+) is a rare example of a metal-oxo cluster isolated and stabilized without additional supporting organic ligands. Herein we report a new method for both the preparation and stabilization in non-aqueous media, which makes these clusters valuable precursors for solution-processed thin films. Solution characterization (NMR, small-angle X-ray scattering and Raman spectroscopy) in wet organic solvents indicated that the clusters evolve via a fragmentation and reaggregation process. This is especially true for hexamers of the smaller Ln(3+)-ions: the higher charge density yields higher hydration rates. This process produced an entirely new hexadecameric cluster formulated Y16O3(OH)24(NO3)18(OSMe2)16(OCMe2)2(H2O)4. The new structure represents an intermediate hydrolysis product on the pathway from hexanuclear clusters to metal oxyhydroxide bulk solid. DMSO solvent ligands displace aqua ligands on the cluster and likely explain the additional stability observed for these clusters in organic solvents. The enhanced cluster stability in DMF and DMSO also enables solution-processing methods to create high quality thin films.

  15. Fabrication of highly textured lithium cobalt oxide films by rapid thermal annealing

    DOEpatents

    Bates, John B.

    2003-05-13

    Systems and methods are described for fabrication of highly textured lithium cobalt oxide films by rapid thermal annealing. A method of forming a lithium cobalt oxide film includes depositing a film of lithium cobalt oxide on a substrate; rapidly heating the film of lithium cobalt oxide to a target temperature; and maintaining the film of lithium cobalt oxide at the target temperature for a target annealing time of at most, approximately 60 minutes. The systems and methods provide advantages because they require less time to implement and are, therefore less costly than previous techniques.

  16. Fabrication of highly textured lithium cobalt oxide films by rapid thermal annealing

    DOEpatents

    Bates, John B.

    2002-01-01

    Systems and methods are described for fabrication of highly textured lithium cobalt oxide films by rapid thermal annealing. A method of forming a lithium cobalt oxide film includes depositing a film of lithium cobalt oxide on a substrate; rapidly heating the film of lithium cobalt oxide to a target temperature; and maintaining the film of lithium cobalt oxide at the target temperature for a target annealing time of at most, approximately 60 minutes. The systems and methods provide advantages because they require less time to implement and are, therefore less costly than previous techniques.

  17. Fabrication of highly textured lithium cobalt oxide films by rapid thermal annealing

    DOEpatents

    Bates, John B.

    2003-04-29

    Systems and methods are described for fabrication of highly textured lithium cobalt oxide films by rapid thermal annealing. A method of forming a lithium cobalt oxide film includes depositing a film of lithium cobalt oxide on a substrate; rapidly heating the film of lithium cobalt oxide to a target temperature; and maintaining the film of lithium cobalt oxide at the target temperature for a target annealing time of at most, approximately 60 minutes. The systems and methods provide advantages because they require less time to implement and are, therefore less costly than previous techniques.

  18. Photoassisted oxidation of oil films on water

    SciTech Connect

    Heller, A.; Brock, J.R.

    1991-08-01

    The objective of the project is to develop TiO{sub 2}-based photocatalysts for the solar assisted oxidative dissolution of oil slicks. In a TiO{sub 2} crystal, absorption of a photon generates an electron-hole pair. The electron reacts with surface-adsorbed oxygen, reducing it to hydrogen peroxide; the hole directly oxidizes adsorbed organic compounds, usually via an intermediate OH radical. Since the density of TiO{sub 2} (3.8g/cc for anatase, 4.3 g/cc for rutile) is greater than that of either oil or seawater, TiO{sub 2} crystals are attached to inexpensive, engineered hollow glass microspheres to ensure flotation on the oil slick surface. Portions of the microsphere surface not covered by TiO{sub 2} are made oleophilic so that the microbeads will be preferentially attracted to the oil-air interface.

  19. Investigation and characterization of oxidized cellulose and cellulose nanofiber films

    NASA Astrophysics Data System (ADS)

    Yang, Han

    Over the last two decades, a large amount of research has focused on natural cellulose fibers, since they are "green" and renewable raw materials. Recently, nanomaterials science has attracted wide attention due to the large surface area and unique properties of nanoparticles. Cellulose certainly is becoming an important material in nanomaterials science, with the increasing demand of environmentally friendly materials. In this work, a novel method of preparing cellulose nanofibers (CNF) is being presented. This method contains up to three oxidation steps: periodate, chlorite and TEMPO (2,2,6,6-tetramethylpiperidinyl-1-oxyl) oxidation. The first two oxidation steps are investigated in the first part of this work. Cellulose pulp was oxidized to various extents by a two step-oxidation with sodium periodate, followed by sodium chlorite. The oxidized products can be separated into three different fractions. The mass ratio and charge content of each fraction were determined. The morphology, size distribution and crystallinity index of each fraction were measured by AFM, DLS and XRD, respectively. In the second part of this work, CNF were prepared and modified under various conditions, including (1) the introduction of various amounts of aldehyde groups onto CNF by periodate oxidation; (2) the carboxyl groups in sodium form on CNF were converted to acid form by treated with an acid type ion-exchange resin; (3) CNF were cross-linked in two different ways by employing adipic dihydrazide (ADH) as cross-linker and water-soluble 1-ethyl-3-[3-(dimethylaminopropyl)] carbodiimide (EDC) as carboxyl-activating agent. Films were fabricated with these modified CNF suspensions by vacuum filtration. The optical, mechanical and thermo-stability properties of these films were investigated by UV-visible spectrometry, tensile test and thermogravimetric analysis (TGA). Water vapor transmission rates (WVTR) and water contact angle (WCA) of these films were also studied.

  20. Oxidation kinetics of YBa 2Cu 3O 7-γ thin films in different oxidizing ambients

    NASA Astrophysics Data System (ADS)

    Gupta, Arunava

    1993-02-01

    The effectiveness of different oxidizer gases (O, O 2, N 2O and NO 2) for the post-growth oxidation of YBa 2Cu 3O 7-γ (YBCO) thin films is investigated. In particular, the oxidation process in the presence of atomic and molecular oxygen is analyzed based on a simple kinetic model involving oxygen adsorption, desorption, and interface transfer steps. It is argued that the high oxidation capability of atomic O is a result of its direct adsorption with very high sticking probability. As a result, the thermodynamic stability range of YBCO at a particular temperature is shifted to significantly lower pressures in an atomic O plasma. On the basis of the known surface decomposition characteristics of N 2O and NO 2, the possible oxidation behavior of YBCO films in the presence of these gases is also discussed.

  1. Electrosynthesis of highly transparent cobalt oxide water oxidation catalyst films from cobalt aminopolycarboxylate complexes.

    PubMed

    Bonke, Shannon A; Wiechen, Mathias; Hocking, Rosalie K; Fang, Xi-Ya; Lupton, David W; MacFarlane, Douglas R; Spiccia, Leone

    2015-04-24

    Efficient catalysis of water oxidation represents one of the major challenges en route to efficient sunlight-driven water splitting. Cobalt oxides (CoOx ) have been widely investigated as water oxidation catalysts, although the incorporation of these materials into photoelectrochemical devices has been hindered by a lack of transparency. Herein, the electrosynthesis of transparent CoOx catalyst films is described by utilizing cobalt(II) aminopolycarboxylate complexes as precursors to the oxide. These complexes allow control over the deposition rate and morphology to enable the production of thin, catalytic CoOx films on a conductive substrate, which can be exploited in integrated photoelectrochemical devices. Notably, under a bias of 1.0 V (vs. Ag/AgCl), the film deposited from [Co(NTA)(OH2 )2 ](-) (NTA=nitrilotriacetate) decreased the transmission by only 10 % at λ=500 nm, but still generated >80 % of the water oxidation current produced by a [Co(OH2 )6 ](2+) -derived oxide film whose transmission was only 40 % at λ=500 nm.

  2. Zinc oxide doped graphene oxide films for gas sensing applications

    SciTech Connect

    Chetna, Kumar, Shani; Chaudhary, S.; Kapoor, A.; Garg, A.; Chowdhuri, A.; Dhingra, V.

    2016-05-06

    Graphene Oxide (GO) is analogous to graphene, but presence of many functional groups makes its physical and chemical properties essentially different from those of graphene. GO is found to be a promising material for low cost fabrication of highly versatile and environment friendly gas sensors. Selectivity, reversibility and sensitivity of GO based gas sensor have been improved by hybridization with Zinc Oxide nanoparticles. The device is fabricated by spin coating of deionized water dispersed GO flakes (synthesized using traditional hummer’s method) doped with Zinc Oxide on standard glass substrate. Since GO is an insulator and functional groups on GO nanosheets play vital role in adsorbing gas molecules, it is being used as an adsorber. Additionally, on being exposed to certain gases the electric and optical characteristics of GO material exhibit an alteration in behavior. For the conductivity, we use Zinc Oxide, as it displays a high sensitivity towards conduction. The effects of the compositions, structural defects and morphologies of graphene based sensing layers and the configurations of sensing devices on the performances of gas sensors were investigated by Raman Spectroscopy, X-ray diffraction(XRD) and Keithley Sourcemeter.

  3. The calculation of band gap energy in zinc oxide films

    NASA Astrophysics Data System (ADS)

    Arif, Ali; Belahssen, Okba; Gareh, Salim; Benramache, Said

    2015-01-01

    We investigated the optical properties of undoped zinc oxide thin films as the n-type semiconductor; the thin films were deposited at different precursor molarities by ultrasonic spray and spray pyrolysis techniques. The thin films were deposited at different substrate temperatures ranging between 200 and 500 °C. In this paper, we present a new approach to control the optical gap energy of ZnO thin films by concentration of the ZnO solution and substrate temperatures from experimental data, which were published in international journals. The model proposed to calculate the band gap energy with the Urbach energy was investigated. The relation between the experimental data and theoretical calculation suggests that the band gap energies are predominantly estimated by the Urbach energies, film transparency, and concentration of the ZnO solution and substrate temperatures. The measurements by these proposal models are in qualitative agreements with the experimental data; the correlation coefficient values were varied in the range 0.96-0.99999, indicating high quality representation of data based on Equation (2), so that the relative errors of all calculation are smaller than 4%. Thus, one can suppose that the undoped ZnO thin films are chemically purer and have many fewer defects and less disorder owing to an almost complete chemical decomposition and contained higher optical band gap energy.

  4. A comparative analysis of graphene oxide films as proton conductors

    NASA Astrophysics Data System (ADS)

    Smirnov, V. A.; Denisov, N. N.; Dremova, N. N.; Vol'fkovich, Y. M.; Rychagov, A. Y.; Sosenkin, V. E.; Belay, K. G.; Gutsev, G. L.; Shulga, N. Yu.; Shulga, Y. M.

    2014-12-01

    The electrical conductivity of graphene oxide (GO) films in vapors of water and acid solutions is found to be close to the conductivity of a film formed after drying the solution of phenol-2,4-disulfonic acid in polyvinyl alcohol, which is known to be a proton conductor. We found that the conductivity of a GO film in vapors of the H2O-H2SO4 electrolyte possesses a sharp maximum at ~1 % by weight of sulfuric acid. The highest conductivity of GO films can be expected when placing the films over acid vapors where the acid concentration is essentially lower than in the acid solutions at their maximum conductivity. Since the conductivity of the H2O-H2SO4 electrolyte itself has a maximum at ~30 % by weight of sulfuric acid, the use of intermediate concentrations of H2SO4 is recommended in practical applications. The GO films permeated with water or acid solution in water are expected to possess the proton-exchange properties similar to those of other proton-exchanging membranes.

  5. Growth of ultrathin titanium oxide films on Ag(110)

    NASA Astrophysics Data System (ADS)

    Sugizaki, Yuichi; Ozawa, Kenichi; Edamoto, Kazuyuki

    2017-08-01

    Titanium oxide films grown on Ag(110) have been investigated by low-energy electron diffraction (LEED), photoelectron spectroscopy (PES), and X-ray absorption spectroscopy (XAS). As Ti atoms were deposited on Ag(110) in O2 at 5.0 × 10-6 Torr and the surface was subsequently annealed at 500 °C for 30 min, a film with a (1×1) periodicity with respect to Ag(110) was formed. The core-level PES study showed that the film was composed of TiO2 in which 1/6 of Ti atoms are reduced to Ti3+. The film gave a (1×1) LEED pattern when the thickness was less than 1 nm. The O K-edge and Ti L-edge XAS measurements showed that each Ti atom in the film was coordinated by 6 O atoms forming a distorted octahedron, as in the case of rutile and anatase TiO2. Analyses of XAS results suggested that the long-range order of the film was similar to that of anatase TiO2.

  6. Reduced graphene oxide/copper nanowire hybrid films as high-performance transparent electrodes.

    PubMed

    Kholmanov, Iskandar N; Domingues, Sergio H; Chou, Harry; Wang, Xiaohan; Tan, Cheng; Kim, Jin-Young; Li, Huifeng; Piner, Richard; Zarbin, Aldo J G; Ruoff, Rodney S

    2013-02-26

    Hybrid films composed of reduced graphene oxide (RG-O) and Cu nanowires (NWs) were prepared. Compared to Cu NW films, the RG-O/Cu NW hybrid films have improved electrical conductivity, oxidation resistance, substrate adhesion, and stability in harsh environments. The RG-O/Cu NW films were used as transparent electrodes in Prussian blue (PB)-based electrochromic devices where they performed significantly better than pure Cu NW films.

  7. rf plasma oxidation of Ni thin films sputter deposited to generate thin nickel oxide layers

    SciTech Connect

    Hoey, Megan L.; Carlson, J. B.; Osgood, R. M. III; Kimball, B.; Buchwald, W.

    2010-10-11

    Nickel oxide (NiO) layers were formed on silicon (Si) substrates by plasma oxidation of nickel (Ni) film lines. This ultrathin NiO layer acted as a barrier layer to conduction, and was an integral part of a metal-insulator-metal (MIM) diode, completed by depositing gold (Au) on top of the oxide. The electrical and structural properties of the NiO thin film were examined using resistivity calculations, current-voltage (I-V) measurements and cross-sectional transmission electron microscopy (XTEM) imaging. The flow rate of the oxygen gas, chamber pressure, power, and exposure time and their influence on the characteristics of the NiO thin film were studied.

  8. Physical investigation of electrophoretically deposited graphene oxide and reduced graphene oxide thin films

    NASA Astrophysics Data System (ADS)

    Politano, Grazia Giuseppina; Versace, Carlo; Vena, Carlo; Castriota, Marco; Ciuchi, Federica; Fasanella, Angela; Desiderio, Giovanni; Cazzanelli, Enzo

    2016-11-01

    Graphene oxide and reduced graphene oxide thin films are very promising materials because they can be used in optoelectronic devices and in a growing range of applications such as touch screens and flexible displays. In this work, graphene oxide (GO) and thermally reduced graphene oxide (rGO) thin films, deposited on Ti/glass substrates, have been obtained by electrophoretic deposition. The morphological and the structural properties of the samples have been investigated by micro-Raman technique, X-ray reflectometry, and SEM analysis. In order to study the optical and electrical properties, variable angle spectroscopic ellipsometry and impedance analysis have been performed. The thermal annealing changes strongly the structural, electrical, and optical properties, because during the thermal processes some amount of sp3 bonds originally present in GO were removed. In particular, the annealing enhances the Ohmic behavior of the rGO film increasing its conductivity and the estimated optical density. Moreover, using electrophoretic deposition, we have found a higher value of optical density for GO thin films, not observed in GO films obtained with other deposition methods.

  9. Photoassisted oxidation of oil films on water

    SciTech Connect

    Heller, A.; Brock, J.R.

    1990-10-01

    The objective of the project is to develop a method for the solar assisted oxidation of oil slicks. A semiconducting photocatalyst, titanium dioxide, is used. Upon absorbing a photon, an electron-hole pair is generated in the TiO{sub 2} microcrystal. The electron reacts with surface-adsorbed oxygen, reducing it to hydrogen peroxide; the hole directly oxidizes adsorbed organic compounds. Titanium dioxide is denser than either oil or seawater; the density of its anatase phase is 3.8 and that of its rutile phase is 4.3. In order to keep the titanium dioxide at the air/oil interface, it is attached to a low density, floating material. The particles of the latter are sufficiently small to make the system economical. Specifically, the photocatalyst particles are attached to inexpensive hollow glass microbeads of about 100{mu}m diameter. Those areas of the microbeads that are not covered by photocatalyst are made oleophilic, so that the microbeads will follow the oil slick and not migrate to either the air/water or the water/oil interface.

  10. Tunable Nanostructures and Crystal Structures in Titanium Oxide Films

    PubMed Central

    2009-01-01

    Controllable nanostructures in spin coated titanium oxide (TiO2) films have been achieved by a very simple means, through change of post deposition annealing temperature. Electron beam imaging and reciprocal space analysis revealed as-deposited TiO2films to be characterized by a dominant anatase phase which converts to the rutile form at 600 °C and reverts to the anatase modification at 1,200 °C. The phase changes are also accompanied by changes in the film microstructure: from regular nanoparticles (as-deposited) to nanowires (600 °C) and finally to dendrite like shapes at 1,200 °C. Photoluminescence studies, Raman spectral results, and X-ray diffraction data also furnish evidence in support of the observed solid state phase transformations in TiO2. PMID:20596447

  11. Enhanced electrochromism in cerium doped molybdenum oxide thin films

    SciTech Connect

    Dhanasankar, M.; Purushothaman, K.K.; Muralidharan, G.

    2010-12-15

    Cerium (5-15% by weight) doped molybdenum oxide thin films have been prepared on FTO coated glass substrate at 250 {sup o}C using sol-gel dip coating method. The structural and morphological changes were observed with the help of XRD, SEM and EDS analysis. The amorphous structure of the Ce doped samples, favours easy intercalation and deintercalation processes. Mo oxide films with 10 wt.% of Ce exhibit maximum anodic diffusion coefficient of 24.99 x 10{sup -11} cm{sup 2}/s and the change in optical transmittance of ({Delta}T at 550 nm) of 79.28% between coloured and bleached state with the optical density of ({Delta}OD) 1.15.

  12. Uptake of Water Onto Organic Films Containing Oxidized Functional Groups

    NASA Astrophysics Data System (ADS)

    Demou, E.; Donaldson, D. J.

    There is increasing evidence that atmospheric particles may contain significant mass fractions of organic compounds. Such particles may be predominantly organic (as in SOA condensates) or may have mixed aqueous-organic character. In either case, the particle surface exposed to the atmosphere, if it has organic character, is subject to oxidation by OH, O3 and NO3 gas phase molecules. Surface oxidation is expected to alter the hydrophobic nature of an organic surface layer, and thus perhaps facilitate the particle's ability to act as a cloud condensation nucleus. We have used a quartz crystal microbalance (QCM) to measure the mass uptake of water by organic films as a func- tion of the ambient relative humidity. Results for the room-temperature condensation of water onto films composed of aliphatic hydrocarbons, mono- and di-alcohols and mono- and di-acids will be presented.

  13. Manganese oxide nanowires, films, and membranes and methods of making

    DOEpatents

    Suib, Steven Lawrence; Yuan, Jikang

    2008-10-21

    Nanowires, films, and membranes comprising ordered porous manganese oxide-based octahedral molecular sieves, and methods of making, are disclosed. A single crystal ultra-long nanowire includes an ordered porous manganese oxide-based octahedral molecular sieve, and has an average length greater than about 10 micrometers and an average diameter of about 5 nanometers to about 100 nanometers. A film comprises a microporous network comprising a plurality of single crystal nanowires in the form of a layer, wherein a plurality of layers is stacked on a surface of a substrate, wherein the nanowires of each layer are substantially axially aligned. A free standing membrane comprises a microporous network comprising a plurality of single crystal nanowires in the form of a layer, wherein a plurality of layers is aggregately stacked, and wherein the nanowires of each layer are substantially axially aligned.

  14. Thin water film formation on metal oxide crystal surfaces.

    PubMed

    Gilbert, Benjamin; Katz, Jordan E; Rude, Bruce; Glover, T E; Hertlein, Marcus P; Kurz, Charles; Zhang, Xiaoyi

    2012-10-09

    Reactions taking place at hydrated metal oxide surfaces are of considerable environmental and technological importance. Surface-sensitive X-ray methods can provide structural and chemical information on stable interfacial species, but it is challenging to perform in situ studies of reaction kinetics in the presence of water. We have implemented a new approach to creating a micrometer-scale water film on a metal oxide surface by combining liquid and gas jets on a spinning crystal. The water films are stable indefinitely and sufficiently thin to allow grazing incidence X-ray reflectivity and spectroscopy measurements. The approach will enable studies of a wide range of surface reactions and is compatible with interfacial optical-pump/X-ray-probe studies.

  15. Review paper: Transparent amorphous oxide semiconductor thin film transistor

    NASA Astrophysics Data System (ADS)

    Kwon, Jang-Yeon; Lee, Do-Joong; Kim, Ki-Bum

    2011-03-01

    Thin film transistors (TFTs) with oxide semiconductors have drawn great attention in the last few years, especially for large area electronic applications, such as high resolution active matrix liquid crystal displays (AMLCDs) and active matrix organic light-emitting diodes (AMOLEDs), because of their high electron mobility and spatial uniform property. This paper reviews and summarizes recent emerging reports that include potential applications, oxide semiconductor materials, and the impact of the fabrication process on electrical performance. We also address the stability behavior of such devices under bias/illumination stress and critical factors related to reliability, such as the gate insulator, the ambient and the device structure.

  16. Vanadium oxide thin film with improved sheet resistance uniformity

    NASA Astrophysics Data System (ADS)

    Généreux, Francis; Provençal, Francis; Tremblay, Bruno; Boucher, Marc-André; Julien, Christian; Alain, Christine

    2014-06-01

    This paper reports on the deposition of vanadium oxide thin films with sheet resistance uniformity better than 2.5% over a 150 mm wafer. The resistance uniformity within the array is estimated to be less than 1%, which is comparable with the value reported for amorphous silicon-based microbolometer arrays. In addition, this paper also shows that the resistivity of vanadium oxide, like amorphous silicon, can be modeled by Arrhenius' equation. This result is expected to significantly ease the computation of the correction table required for TEC-less operation of VOx-based microbolometer arrays.

  17. Luminescent sulfides and solution-deposited oxide thin films

    NASA Astrophysics Data System (ADS)

    Anderson, Jeremy T.

    Solid state luminescent sulfides are prepared as powders in order to elucidate the relationship between structure and light emission. While the sulfides studied in this dissertation are known phosphors, materials are investigated in a variety of new ways. Elementary properties and structures of MgS are reviewed, and preparation of MgS is described with sufficient detail that it may be reproduced in laboratories worldwide. Luminescence of MgS:Eu is evaluated, primarily by interpretation of published work. Solid pellets of MgS:Eu are created for the purpose of depositing thin-film layers by physical vapor deposition, and incorporating the phosphor layer within ACTFEL structures. Fabricated devices are found to exhibit bright ACTFEL luminescence--the brightest known for MgS. Similarly, MgS films are doped with a variety of lanthanide atoms to investigate the hot-electron distribution in MgS layers during device operation. The system BaGa2S4--SrGa 2S4 is evaluated for mutual solid phase solubility. Addition of Eu2+ causes each of these phases to photoluminescence. The emission energies (and therefore colors) are adjusted according to composition. Thin-film oxides are deposited from solution sources. Solution-deposited ZnO serves as the semiconductor layer in transparent thin-film transistor devices. A new class of dielectric material is also developed by solution methods. HafSOx and ZircSOx films, and derivative compositions, are evaluated in simple capacitor structures and demonstrated in functioning transistor devices. High-resolution nanolaminate structures are also constructed from this class of materials. From the knowledge and experience of developing oxide thin-films, more general chemical strategies are expressed.

  18. Oxidative stability of LARC (tm)-TPI films

    NASA Technical Reports Server (NTRS)

    Hinkley, Jeffrey A.

    1992-01-01

    The oxidative aging of 50-micron-thick films of LARC-TPI was studied using conventional thermogravimetric techniques and measurements of plane-stress fracture toughness. It was shown that at high temperature, most of the toughness loss occurred very early relative to the weight loss. The difficulties of interpreting TGA results in this regime and the problems of extrapolations to long times are discussed.

  19. The structure of nickel and indium oxide thin films from EXAFS data

    NASA Astrophysics Data System (ADS)

    Bets, V.; Zamozdiks, T.; Lusis, A.; Purans, J.; Bausk, N.; Sheromov, M.

    1987-11-01

    The structure of nickel oxide and indium oxide doped by tin films prepared by reactive magnetron sputtering has been studied by the EXAFS method. It has been found that the nickel oxide thin film has a microcrystalline structure with significant disorder proved by the increase of the Debye-Waller factor and the sharp decrease of peak amplitudes. The indium oxide thin film has a noticeable structural disorder due to 8% tin dopping.

  20. Photocatalytic oxide films in the built environment

    NASA Astrophysics Data System (ADS)

    Österlund, Lars; Topalian, Zareh

    2014-11-01

    The possibility to increase human comfort in buildings is a powerful driving force for the introduction of new technology. Among other things our sense of comfort depends on air quality, temperature, lighting level, and the possibility of having visual contact between indoors and outdoors. Indeed there is an intimate connection between energy, comfort, and health issues in the built environment, leading to a need for intelligent building materials and green architecture. Photocatalytic materials can be applied as coatings, filters, and be embedded in building materials to provide self-cleaning, antibacterial, air cleaning, deodorizing, and water cleaning functions utilizing either solar light or artificial illumination sources - either already present in buildings, or by purposefully designed luminaries. Huge improvements in indoor comfort can thus be made, and also alleviate negative health effects associated with buildings, such as the sick-house syndrome. At the same time huge cost savings can be made by reducing maintenance costs. Photocatalytic oxides can be chemically modified by changing their acid-base surface properties, which can be used to overcome deactivation problems commonly encountered for TiO2 in air cleaning applications. In addition, the wetting properties of oxides can be tailored by surface chemical modifications and thus be made e.g. oleophobic and water repellent. Here we show results of surface acid modified TiO2 coatings on various substrates by means of photo-fixation of surface sulfate species by a method invented in our group. In particular, we show that such surface treatments of photocatalytic concrete made by mixing TiO2 nanoparticles in reactive concrete powders result in concrete surfaces with beneficial self-cleaning properties. We propose that such approaches are feasible for a number of applications in the built environment, including glass, tiles, sheet metals, plastics, etc.

  1. Oxidation of electrodeposited black chrome selective solar absorber films

    SciTech Connect

    Holloway, P.H.; Shanker, K.; Pettit, R.B.; Sowell, R.R.

    1980-01-01

    X-ray photoelectron and Auger electron spectroscopies have been used to study the composition and oxidation of electrodeposited black chrome films. The outer layer of the film is Cr/sub 2/O/sub 3/ with the inner layer being a continuously changing mixture of Cr + Cr/sub 2/O/sub 3/. Initially, approximately 40% by volume of the film is combined as Cr/sub 2/O/sub 3/, and the volume percentage of Cr/sub 2/O/sub 3/ increases to greater than 60% after only 136 hours at 250/sup 0/C. After approximately 3600 hours at 400/sup 0/C, the volume percentage of Cr/sub 2/O/sub 3/ increased to as high as 80%. The thermal emittance decreased approximately linearly with increasing oxide content, while the solar absorptance remained constant until the percentage of Cr/sub 2/O/sub 3/ exceeded approximately 70%. Oxidation was slower when the Cr/sup +3/ concentration in the plating bath was reduced from 16 g/l to 8 g/l, and when black chrome was deposited on stainless steel rather than sulfamate nickel.

  2. Electrochromic Properties of Tungsten Oxide Films Prepared by Reactive Sputtering

    NASA Astrophysics Data System (ADS)

    Kim, Min Hong; Kang, Tai Young; Jung, Yu Sup; Kim, Kyung Hwan

    2013-05-01

    WO3-x thin films were deposited on induim tin oxide (ITO) glass substrates with various oxygen flow ratios from 0.55 to 0.7 by the reactive facing-target sputtering method, at a power density of 4 W/cm2 and room temperature. The structural properties of the WO3-x thin films were measured by X-ray diffractometry and Raman spectral analysis. As-deposited WO3-x thin films had an amorphous structure. In the Raman spectra, WO3-x thin films exhibited two strong peaks at 770 and 950 cm-1 attributed to the vibrations of W6+-O and W6+=O bonds, respectively. The electrochemical and optical properties of WO3-x thin films were measured by cyclic voltammetry and UV/vis spectrometry. The results showed the highest charge density at an oxygen flow ratio of 0.7 and the highest transmittance in the visible range. The maximum coloration efficiency was 30.82 cm2/C at an oxygen flow ratio of 0.7.

  3. Electrical properties of vanadium tungsten oxide thin films

    SciTech Connect

    Nam, Sung-Pill; Noh, Hyun-Ji; Lee, Sung-Gap; Lee, Young-Hie

    2010-03-15

    The vanadium tungsten oxide thin films deposited on Pt/Ti/SiO{sub 2}/Si substrates by RF sputtering exhibited good TCR and dielectric properties. The dependence of crystallization and electrical properties are related to the grain size of V{sub 1.85}W{sub 0.15}O{sub 5} thin films with different annealing temperatures. It was found that the dielectric properties and TCR properties of V{sub 1.85}W{sub 0.15}O{sub 5} thin films were strongly dependent upon the annealing temperature. The dielectric constants of the V{sub 1.85}W{sub 0.15}O{sub 5} thin films annealed at 400 {sup o}C were 44, with a dielectric loss of 0.83%. The TCR values of the V{sub 1.85}W{sub 0.15}O{sub 5} thin films annealed at 400 {sup o}C were about -3.45%/K.

  4. Strain-induced phenomenon in complex oxide thin films

    NASA Astrophysics Data System (ADS)

    Haislmaier, Ryan

    Complex oxide materials wield an immense spectrum of functional properties such as ferroelectricity, ferromagnetism, magnetoelectricity, optoelectricity, optomechanical, magnetoresistance, superconductivity, etc. The rich coupling between charge, spin, strain, and orbital degrees of freedom makes this material class extremely desirable and relevant for next generation electronic devices and technologies which are trending towards nanoscale dimensions. Development of complex oxide thin film materials is essential for realizing their integration into nanoscale electronic devices, where theoretically predicted multifunctional capabilities of oxides could add tremendous value. Employing thin film growth strategies such as epitaxial strain and heterostructure interface engineering can greatly enhance and even unlock novel material properties in complex oxides, which will be the main focus of this work. However, physically incorporating oxide materials into devices remains a challenge. While advancements in molecular beam epitaxy (MBE) of thin film oxide materials has led to the ability to grow oxide materials with atomic layer precision, there are still major limitations such as controlling stoichiometric compositions during growth as well as creating abrupt interfaces in multi-component layered oxide structures. The work done in this thesis addresses ways to overcome these limitations in order to harness intrinsic material phenomena. The development of adsorption-controlled stoichiometric growth windows of CaTiO3 and SrTiO3 thin film materials grown by hybrid MBE where Ti is supplied using metal-organic titanium tetraisopropoxide material is thoroughly outlined. These growth windows enable superior epitaxial strain-induced ferroelectric and dielectric properties to be accessed as demonstrated by chemical, structural, electrical, and optical characterization techniques. For tensile strained CaTiO3 and compressive strained SrTiO 3 films, the critical effects of

  5. The synthesis and characterization of multifunctional oxide thin films

    NASA Astrophysics Data System (ADS)

    Kharel, Parashu Ram

    2008-10-01

    Multifunctional materials offer a number of very interesting properties for developing new generation novel devices. Motivated by this fact, we concentrated our research efforts on investigating two different class of multifunctional materials namely: Diluted Magnetic Semiconducting Oxides (DMSO) and Multiferroic Oxides. The primary goal of this study was to determine how to resolve the controversy concerning the origin of room temperature ferromagnetic order in DMSO and to demonstrate the theoretically predicted coupling between ferroelectric and magnetic order parameters in multiferroic oxides. We chose several materials of current interest such as TiO2, ZnOand In2O3 (DMSO) and Ni3V2O8 and BiFeO 3 (multiferroic oxides) as the experimental specimens. We synthesized thin film samples of these materials using metal organic decomposition by spin coating and RF magnetron sputtering techniques. We succeeded in growing single phase polycrystalline thin films using both of the techniques with the sputter deposited samples showing highly preferred orientations. We did not observe any secondary phases and accidental impurities leading to robust ferromagnetic order in our samples within the detection limit of XRD, Raman spectroscopy and TEM. We have demonstrated that the lattice defects such as oxygen vacancies and cation vacancies play crucial role in the development of ferromagnetic order in DMSO materials. Based on the investigation carried out on TiO 2, ZnO and In2O3, we conclude that ferromagnetism can be developed in oxygen deficient DMSO thin films without the subbstitution of any external magnetic impurities but the incorporation of magnetic impurities may help in stabilizing the observed ferromagnetic order. Most importantly, we demonstrated with the direct measurement of spin polarization in In 2O3 and Cr doped In2O3 thin films that the charge carriers responsible for the ferromagnetic order are spin polarized. We have successfully demonstrated that the low

  6. Oxidation Temperature Effects on ZnO Thin Films Prepared from Zn Thin Films on Quartz Substrates.

    PubMed

    Park, Seonhee; Kim, Younggyu; Leem, Jae-Young

    2015-11-01

    We investigated the structural and optical properties of the ZnO thin films formed by oxidation of Zn thin films. Zn thin films were deposited by thermal evaporation and were then annealed from 300 to 800 degrees C to prepare ZnO thin films. We found that ZnO thin films were formed by thermal oxidation of Zn thin films at oxidation temperatures over 400 degrees C. The grain size of ZnO thin films increased with the oxidation temperature and the highest ZnO (002) intensity was obtained at 600 degrees C. In the PL spectra, the intensity of the near-band-edge peak increased with the oxidation temperatures until 400 degrees C. However, these values gradually decreased with a further increase in the oxidation temperatures over 400 degrees C. The transmittance of the ZnO thin films was more than 90% for the visible wavelength region, and the optical band gap was red-shifted with increase in the oxidation temperature.

  7. Electrochemical deposition of conducting ruthenium oxide films from solution

    SciTech Connect

    Anderson, D.P.; Warren, L.F.

    1984-02-01

    In the last decade, ruthenium oxide, RuO /sub x/ (x less than or equal to 2), has been used extensively as the active anode electrocatalyst constituent for Cl/sub 2/ and O/sub 2/ evolution reactions, in chlorate production, and in metal electrowinning from mixed chloride-sulfate solutions. More recently, this material has been incorporated in several light-induced water electrolysis schemes and apparently possesses the ability to inhibit CdS photocorrosion by acting as a hole scavenger. The numerous applications for this catalyst material certainly warrant further studies of its electrochemical properties on a variety of substrates, e.g., semiconductors. The lack of a simple technique for controlled deposition of ruthenium oxide onto conducting substrates prompted us to investigate an electrochemical approach to this problem. We describe here a new way to electrochemically deposit conducting films of hydrated ruthenium oxide from an aqueous solution of the benzeneruthenium (II)aqua complex. The films slowly dissolve in aqueous electrolytes upon potential cycling, yet appear to be catalytic with regards to water oxidation.

  8. Functionalization of nanostructured cerium oxide films with histidine.

    PubMed

    Tsud, Nataliya; Bercha, Sofiia; Acres, Robert G; Vorokhta, Mykhailo; Khalakhan, Ivan; Prince, Kevin C; Matolín, Vladimír

    2015-01-28

    The surfaces of polycrystalline cerium oxide films were modified by histidine adsorption under vacuum and characterized by the synchrotron based techniques of core and valence level photoemission, resonant photoemission and near edge X-ray absorption spectroscopy, as well as atomic force microscopy. Histidine is strongly bound to the oxide surface in the anionic form through the deprotonated carboxylate group, and forms a disordered molecular adlayer. The imidazole ring and the amino side group do not form bonds with the substrate but are involved in the intermolecular hydrogen bonding which stabilizes the molecular adlayer. The surface reaction with histidine results in water desorption accompanied by oxide reduction, which is propagated into the bulk of the film. Previously studied, well-characterized surfaces are a guide to the chemistry of the present polycrystalline surface and histidine bonds via the carboxylate group in both cases. In contrast, bonding via the imidazole group occurs on the well-ordered surface but not in the present case. The morphology and structure of the cerium oxide are decisive factors which define the adsorption geometry of the histidine adlayer.

  9. Oxide Film and Porosity Defects in Magnesium Alloy AZ91

    SciTech Connect

    Wang, Liang; Rhee, Hongjoo; Felicelli, Sergio D.; Sabau, Adrian S; Berry, John T.

    2009-01-01

    Porosity is a major concern in the production of light metal parts. This work aims to identify some of the mechanisms of microporosity formation in magnesium alloy AZ91. Microstructure analysis was performed on several samples obtained from gravity-poured ingots in graphite plate molds. Temperature data during cooling was acquired with type K thermocouples at 60 Hz at three locations of each casting. The microstructure of samples extracted from the regions of measured temperature was then characterized with optical metallography. Tensile tests and conventional four point bend tests were also conducted on specimens cut from the cast plates. Scanning electron microscopy was then used to observe the microstructure on the fracture surface of the specimens. The results of this study revealed the existence of abundant oxide film defects, similar to those observed in aluminum alloys. Remnants of oxide films were detected on some pore surfaces, and folded oxides were observed in fracture surfaces indicating the presence of double oxides entrained during pouring.

  10. Synthesis of nanoporous activated iridium oxide films by anodized aluminum oxide templated atomic layer deposition.

    SciTech Connect

    Comstock, D. J.; Christensen, S. T.; Elam, J. W.; Pellin, M. J.; Hersam, M. C.

    2010-08-01

    Iridium oxide (IrOx) has been widely studied due to its applications in electrochromic devices, pH sensing, and neural stimulation. Previous work has demonstrated that both Ir and IrOx films with porous morphologies prepared by sputtering exhibit significantly enhanced charge storage capacities. However, sputtering provides only limited control over film porosity. In this work, we demonstrate an alternative scheme for synthesizing nanoporous Ir and activated IrOx films (AIROFs). This scheme utilizes atomic layer deposition to deposit a thin conformal Ir film within a nanoporous anodized aluminum oxide template. The Ir film is then activated by potential cycling in 0.1 M H{sub 2}SO{sub 4} to form a nanoporous AIROF. The morphologies and electrochemical properties of the films are characterized by scanning electron microscopy and cyclic voltammetry, respectively. The resulting nanoporous AIROFs exhibit a nanoporous morphology and enhanced cathodal charge storage capacities as large as 311 mC/cm{sup 2}.

  11. Magnetic transparent conducting oxide film and method of making

    DOEpatents

    Windisch, Jr., Charles F.; Exarhos, Gregory J.; Sharma, Shiv K.

    2004-07-13

    Cobalt-nickel oxide films of nominal 100 nm thickness, and resistivity as low as 0.06 .OMEGA..multidot.cm have been deposited by spin-casting from both aqueous and organic precursor solutions followed by annealing at 450.degree. C. in air. Films deposited on sapphire substrates exhibit a refractive index of about 1.7 and are relatively transparent in the wavelength region from 0.6 to 10.0 .mu.m. They are also magnetic. The electrical and spectroscopic properties of the oxides have been studied as a function of x=Co/(Co+Ni) ratio. An increase in film resistivity was found upon substitution of other cations (e.g., Zn.sup.2+, Al.sup.3+) for Ni in the spinel structure. However, some improvement in the mechanical properties of the films resulted. On the other hand, addition of small amounts of Li decreased the resistivity. A combination of XRD, XPS, UV/Vis and Raman spectroscopy indicated that NiCo.sub.2 O.sub.4 is the primary conducting component and that the conductivity reaches a maximum at this stoichiometry. When x<0.67, NiO forms leading to an increase in resistivity; when x>0.67, the oxide was all spinel but the increased Co content lowered the conductivity. The influence of cation charge state and site occupancy in the spinel structure markedly affects calculated electron band structures and contributes to a reduction of p-type conductivity, the formation of polarons, and the reduction in population of mobile charge carriers that tend to limit transmission in the infrared.

  12. Isothermal thermogravimetric analysis of soybean oil oxidation correlated to thin film micro-oxidation test methods

    USDA-ARS?s Scientific Manuscript database

    A method of correlation between the Thin Film Micro-Oxidation (TFMO) test with isothermal thermogravimetric analysis is reported utilizing a soybean oil system. Utilizing a kinetic model, pseudo-rate constants and “activation energy” can be calculated from weight loss data. This model accounts for o...

  13. Self-formed copper oxide contact interlayer for high-performance oxide thin film transistors

    SciTech Connect

    Gao, Xu E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Aikawa, Shinya; Mitoma, Nobuhiko; Lin, Meng-Fang; Kizu, Takio; Tsukagoshi, Kazuhito E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Nabatame, Toshihide

    2014-07-14

    Oxide thin film transistor employing copper source/drain electrodes shows a small turn on voltage and reduced hysteresis. Cross-sectional high-resolution transmission electron microscopy image confirmed the formation of ∼4 nm CuO{sub x} related interlayer. The lower bond-dissociation energy of Cu-O compared to Si-O and In-O suggests that the interlayer was formed by adsorbing oxygen molecules from surrounding environment instead of getting oxygen atoms from the semiconductor film. The formation of CuO{sub x} interlayer acting as an acceptor could suppress the carrier concentration in the transistor channel, which would be utilized to control the turn on voltage shifts in oxide thin film transistors.

  14. Multi-technique surface charaterization of oxide films on electropolished and anodically oxidized titanium

    NASA Astrophysics Data System (ADS)

    Lausmaa, Jukka; Kasemo, Bengt; Mattsson, Håkan; Odelius, Hans

    1990-11-01

    The widespread use of pure Ti in biomedical applications and in basic biomaterials research has led to an increasing interest in the properties of its surface oxides, and how they can be modified. In this work, which was part of a broad surface characterization of oxide films on pure Ti and Ti-6A1-4V, the chemical composition of anodic oxide films formed on pure Ti during electropolishing and anodic oxidation was investigated using multi-technique surface analysis (XPS, AES/SAM, SIMS, RBS and NRA). XPS and AES Ti line shapes show that the oxide formed is mainly TiO 2, but the chemical composition can be modified by anion adsorption and/or incorporation when H 2SO 4 or H 3PO 4 electrolytes are used. Modification of the anodic oxide film composition also occurs during sterilization; increased Ca and H levels are observed by SIMS and NRA after autoclaving. AES and XPS depth profiles, together with RBS measurements, show that the oxide thickness depends linearly on the anodizing potential in the range 5-80 V, with a growth constant α m≈ 1.1 × 10 16 oxygen atoms/V⋯ cm 2. The present results are compared with parallel studies of the composition and microstructure of thermal and anodic oxides on pure Ti and Ti-6A1-4V. The demonstrated systematic variation of oxide properties opens up the possibility to study the influence of specific surface properties on the biological response to Ti materials.

  15. Thin copper oxide films prepared by ion beam sputtering with subsequent thermal oxidation: Application in chemiresistors

    NASA Astrophysics Data System (ADS)

    Horak, P.; Bejsovec, V.; Vacik, J.; Lavrentiev, V.; Vrnata, M.; Kormunda, M.; Danis, S.

    2016-12-01

    Copper oxide films were prepared by thermal oxidation of thin Cu films deposited on substrates by ion beam sputtering. The subsequent oxidation was achieved in the temperature range of 200 °C-600 °C with time of treatment from 1 to 7 h (with a 1-h step) in a furnace open to air. At temperatures 250 °C-600 °C, the dominant phase formed was CuO, while at 200 °C mainly the Cu2O phase was identified. However, the oxidation at 200 °C led to a more complicated composition - in the depth Cu2O phase was observed, though in the near-surface layer the CuO dominant phase was found with a significant presence of Cu(OH)2. A limited amount of Cu2O was also found in samples annealed at 600 °C. The sheet resistance RS of the as-deposited Cu sample was 2.22 Ω/□, after gradual annealing RS was measured in the range 2.64 MΩ/□-2.45 GΩ/□. The highest RS values were obtained after annealing at 300 °C and 350 °C, respectively. Oxygen depth distribution was studied using the 16O(α,α) nuclear reaction with the resonance at energy 3032 keV. It was confirmed that the higher oxidation degree of copper is located in the near-surface region. Preliminary tests of the copper oxide films as an active layer of a chemiresistor were also performed. Hydrogen and methanol vapours, with a concentration of 1000 ppm, were detected by the sensor at an operating temperature of 300 °C and 350 °C, respectively. The response of the sensors, pointed at the p-type conductivity, was improved by the addition of thin Pd or Au catalytic films to the oxidic film surface. Pd-covered films showed an increased response to hydrogen at 300 °C, while Au-covered films were more sensitive to methanol vapours at 350 °C.

  16. Photocatalysis of zinc oxide nanotip array/titanium oxide film heterojunction prepared by aqueous solution deposition

    NASA Astrophysics Data System (ADS)

    Lee, Ming-Kwei; Lee, Bo-Wei; Kao, Chen-Yu

    2017-05-01

    A TiO2 film was prepared on indium tin oxide (ITO)/glass by aqueous solution deposition (ASD) with precursors of ammonium hexafluoro-titanate and boric acid at 40 °C. The photocatalysis of annealed TiO2 film increases with increasing growth time and decreases with increasing growth times longer than 60 min. A ZnO nanotip array was prepared on ZnO seed layer/TiO2 film/glass by aqueous solution deposition with precursors of zinc nitrate and ammonium hydroxide at 70 °C. The photocatalysis of ASD-ZnO/ASD-TiO2 film/ITO glass can be better than that of P25.

  17. Reduction–Oxidation Photocycle Dynamics of Flavins in Starch Films

    PubMed Central

    Penzkofer, Alfons

    2012-01-01

    The blue-light photo-reduction (conversion of oxidized flavin quinone via flavin semiquinone to fully reduced flavin hydroquinone) and dark re-oxidation of the flavins riboflavin and lumiflavin in starch (α-amylose) films was studied by absorption and luminescence spectroscopy. Blue-light photo-excitation caused an absorption, fluorescence, and phosphorescence decrease which recovered in the dark. The photo-reduction dark-oxidation cycle could be repeated. The efficiency of photo-reduction decreased with exposed excitation energy, and the speed of re-oxidation in the dark slowed down with time after excitation. The absorption did not fully recover. The fluorescence efficiency after a long time of storage in the dark increased beyond the initial flavin quinone fluorescence efficiency. Flavin photo-excitation is thought to cause starch-flavin restructuring (static fluorescence quenching center formation), enabling enhanced photo-induced starch to flavin electron transfer with subsequent flavin reduction and starch oxidation. In the dark, after light switch-off, thermal reversion of flavin reduction and starch oxidation occurred. PMID:22942758

  18. Improved Charge Transfer by Thin Metal Oxide Films

    NASA Astrophysics Data System (ADS)

    Irfan

    The field of electronics has an immense impact on our day to day life. Efficient charge transfer at the semiconductor and electrode interface is one of the most crucial issues for the performance of any electronic device. A lot of effort has been spent to address this issue. A counter intuitive phenomenon of insertion of a thin metal oxide film at the semiconductor and electrode interface has gained momentum recently. In the current thesis, based on results of several experiments, I will propose a prominent mechanism of performance improvement with such insertions. I will also demonstrate the applicability of such metal oxide thin films in many other systems. First, I will introduce the scope of the thesis in detail. I will also introduce the background to understand the electronic structure of organic semiconductors, along with the interface formation at the semiconductor/metal interface. Then, I will discuss the measurement techniques. I will start the discussion on results with the insertion of a thin layer of MoOx (a transition metal oxide) between indium tin oxide (ITO) and two well studied organic semiconductors. I will also demonstrate that the optimum insertion layer thickness is just a few nanometers. I will illustrate the importance of high vacuum during the deposition of such insertion layers. I will also discuss the method to recover work function of air exposed MoOx films. I will further demonstrate that a thin layer of MoOx can be utilized to dope C60 strongly p-type. Then, I will discuss the application of MoO x insertion layer in CdTe based solar cells. I will further show the application of MoOx and organic double-inter-layer in organic devices. At the end, I will discuss an intense oxygen plasma treatment on ITO films and demonstrate a method to achieve high work function ITO films. The mechanism of high work function and application in devices will also be explained in detail. Finally, I will summarize the thesis.

  19. Synthesis and energy applications of oriented metal oxide nanoporous films

    NASA Astrophysics Data System (ADS)

    Wu, Qingliu

    This dissertation mainly addresses the synthesis of well-ordered mesoporous titania thin films by dip coating with PEO-PPO-PEO triblock copolymer surfactant template P123. Because P123 is composed of poly(ethylene oxide) [PEO] and poly(propylene oxide) [PPO] blocks, concentrations of ingredients are adjusted to tune the films' wall thickness, pore size and mesophase. Structural changes are consistent with partitioning of species among PEO blocks, PPO blocks, and the PEO/PPO interface. Titanates localize near PEO and increase wall thickness (by 5 nm to 7 nm). Depending on aging temperature, PPG either swells the PPO cores (when it is hydrophobic) or introduces large (>200 nm) voids (when it is hydrophilic but phase separates during heating). 1-butanol localizes at the PEO/PPO interface to favor a 3D hexagonal mesostructure. In another approach, anodizing Ti foils yields vertically aligned titania nanotubes arrays with exceptional stabilities as anodes in lithium ion batteries; they maintain capacities of 130-230 mAhg-1 over 200 cycles. No microstructural changes are induced by battery cycling and good electrical contact is maintained. A diffusion induced stress model suggests that thin-walled nanotubes arrays should be stable under testing conditions, and that ordered hexagonal columnar pore arrays should have both high charge/discharge rates and low stress development. KEY WORDS: materials synthesis, porous, thin film, alternative energy, self-assembly

  20. CSA doped polypyrrole-zinc oxide thin film sensor

    NASA Astrophysics Data System (ADS)

    Chougule, M. A.; Jundale, D. M.; Raut, B. T.; Sen, Shashwati; Patil, V. B.

    2013-02-01

    The polypyrrole-zinc oxide (PPy-ZnO) hybrid sensor doped with different weight ratios of camphor sulphonic acid (CSA) were prepared by spin coating technique. These CSA doped PPy-ZnO hybrids were characterized by field emission scanning electron microscope (FESEM) and fourier transform infrared (FTIR) which proved the formation of polypyrrole, PPy-ZnO and the interaction between polypyrrole - ZnO (PPy-ZnO) hybrid with CSA doping. The gas sensing properties of the PPy-ZnO hybrid films doped with CSA have been studied for oxidizing (NO2) as well as reducing (H2S, NH3, CH4OH and CH3OH) gases at room temperature. We demonstrate that CSA doped PPy-ZnO hybrid films are highly selective to NO2 along with high-sensitivity at low concentration (80% to 100 ppm) and better stability, which suggested that the CSA doped PPy-ZnO hybrid films are potential candidate for NO2 detection at room temperature.

  1. Amorphous nickel incorporated tin oxide thin film transistors

    NASA Astrophysics Data System (ADS)

    Yang, Jianwen; Ren, Jinhua; Lin, Dong; Han, Yanbing; Qu, Mingyue; Pi, Shubin; Fu, Ruofan; Zhang, Qun

    2017-09-01

    Nickel as a dopant has been proposed to suppress excess carrier concentration in n-type tin oxide based thin film transistors (TFTs). The influences of Ni content on nickel doped tin oxide (TNO) thin films and their corresponding TFTs were investigated with experimental results showing that the TNO thin films are amorphous. Through the comparison of the transfer characteristic curves of the TNO TFTs with different Ni contents, it was observed that Ni doping is useful to improve the performance of SnO2-based TFTs by suppressing the off-state current and shifting the threshold voltage to 0 V. The amorphous TNO TFT with 3.3 at.% Ni content shows optimum performance, with field effect mobility of 8.4 cm2 V-1 s-1, saturation mobility of 6.8 cm2 V-1 s-1, subthreshold swing value of 0.8 V/decade, and an on-off current ratio of 2.1  ×  107. Nevertheless, the bias stress stability of SnO2-based TFTs deteriorate.

  2. Holographic grating formation in laser-deposited aluminium-doped zinc oxide and indium tin oxide films

    NASA Astrophysics Data System (ADS)

    Thestrup, Birgitte; Dam-Hansen, Carsten; Schou, Jørgen; Johansen, Per Michael

    2000-05-01

    Holographic grating formation is demonstrated in films of the transparent and semiconducting materials aluminium-doped zinc oxide (AZO) and indium tin oxide (ITO) produced by pulsed laser deposition. The holographic gratings are induced by UV laser light at 356 nm. The physics and characteristics of grating formation in laser-deposited AZO and ITO films are compared with those of sputter-deposited indium oxide and ITO films, which have been previously used as holographic recorders. It is found that the optical response of laser-deposited AZO films are superior to that of ITO films. The AZO films exhibited an average transmission in the visible wavelength range of over 90%, and grating diffraction efficiencies of 3 × 10-6 in 200 nm thick films.

  3. Oxidation of rubrene thin films: an electronic structure study.

    PubMed

    Sinha, Sumona; Wang, C-H; Mukherjee, M; Mukherjee, T; Yang, Y-W

    2014-12-30

    The performances of organic semiconductor devices are crucially linked with their stability at the ambient atmosphere. The evolution of electronic structures of 20 nm thick rubrene films exposed to ambient environment with time has been studied by UV and X-ray photoemission spectroscopy (UPS and XPS), near edge X-ray absorption fine structure (NEXAFS) spectroscopy, and density functional theory (DFT). XPS, NEXAFS data, and DFT calculated values suggest the formation of rubrene-epoxide and rubrene-endoperoxide through reaction of tetracene backbone with oxygen of ambient environment. Angle dependent XPS measurement indicates that the entire probed depth of the films reacts with oxygen by spending only about 120 min in ambient environment. The HOMO peak of pristine rubrene films almost disappears by exposure of 120 min to ambient environment. The evolution of the valence band (occupied states) and NEXAFS (unoccupied states) spectra indicates that the films become more insulating with exposure as the HOMO-LUMO gap increases on oxidation. Oxygen induced chemical reaction completely destroys the delocalized nature of the electron distribution in the tetracene backbone of rubrene. The results are relevant to the performance and reliability of rubrene based devices in the environment.

  4. Atomic Structure Refinement of Pbnm-type Perovskite Oxide Films

    NASA Astrophysics Data System (ADS)

    Choquette, Amber; Smith, Cole; May, Steve

    Complex ABO3 oxide heterostructures are of interest due to their wide variety of electronic, optical, and magnetic properties. One of the controlling factors to these functionalities is the distortions and rotations of the corner-connected BO6 octahedral network. This BO6 octahedra network directly couples to the electronic bandwidth of these materials, but the inability to determine the full atomic structure in thin films has inhibited quantitative understanding of how factors such as epitaxial strain alter the octahedral rotations in this broad class of materials. Earlier work of has demonstrate that half-order diffraction peaks can be used to quantify octahedral rotations in thin strained films. Here, we build on this approach to solve for both the oxygen and A-site positions in films of the commonly occurring Pbnm structure type. We present on epitaxial RFeO3 heterostructures, where R is a rare earth element, to demonstrate the feasibility of quantifying oxygen and A-site displacements in films using synchrotron diffraction. This work is supported by the National Science Foundation (DMR-1151649).

  5. Highly conductive grain boundaries in copper oxide thin films

    NASA Astrophysics Data System (ADS)

    Deuermeier, Jonas; Wardenga, Hans F.; Morasch, Jan; Siol, Sebastian; Nandy, Suman; Calmeiro, Tomás; Martins, Rodrigo; Klein, Andreas; Fortunato, Elvira

    2016-06-01

    High conductivity in the off-state and low field-effect mobility compared to bulk properties is widely observed in the p-type thin-film transistors of Cu2O, especially when processed at moderate temperature. This work presents results from in situ conductance measurements at thicknesses from sub-nm to around 250 nm with parallel X-ray photoelectron spectroscopy. An enhanced conductivity at low thickness is explained by the occurrence of Cu(II), which is segregated in the grain boundary and locally causes a conductivity similar to CuO, although the surface of the thick film has Cu2O stoichiometry. Since grains grow with an increasing film thickness, the effect of an apparent oxygen excess is most pronounced in vicinity to the substrate interface. Electrical properties of Cu2O grains are at least partially short-circuited by this effect. The study focuses on properties inherent to copper oxide, although interface effects cannot be ruled out. This non-destructive, bottom-up analysis reveals phenomena which are commonly not observable after device fabrication, but clearly dominate electrical properties of polycrystalline thin films.

  6. Highly conductive grain boundaries in copper oxide thin films

    SciTech Connect

    Deuermeier, Jonas; Wardenga, Hans F.; Morasch, Jan; Siol, Sebastian; Klein, Andreas; Nandy, Suman; Calmeiro, Tomás; Martins, Rodrigo; Fortunato, Elvira

    2016-06-21

    High conductivity in the off-state and low field-effect mobility compared to bulk properties is widely observed in the p-type thin-film transistors of Cu{sub 2}O, especially when processed at moderate temperature. This work presents results from in situ conductance measurements at thicknesses from sub-nm to around 250 nm with parallel X-ray photoelectron spectroscopy. An enhanced conductivity at low thickness is explained by the occurrence of Cu(II), which is segregated in the grain boundary and locally causes a conductivity similar to CuO, although the surface of the thick film has Cu{sub 2}O stoichiometry. Since grains grow with an increasing film thickness, the effect of an apparent oxygen excess is most pronounced in vicinity to the substrate interface. Electrical properties of Cu{sub 2}O grains are at least partially short-circuited by this effect. The study focuses on properties inherent to copper oxide, although interface effects cannot be ruled out. This non-destructive, bottom-up analysis reveals phenomena which are commonly not observable after device fabrication, but clearly dominate electrical properties of polycrystalline thin films.

  7. Surfactant-assisted ultrasonic spray pyrolysis of nickel oxide and lithium-doped nickel oxide thin films, toward electrochromic applications

    NASA Astrophysics Data System (ADS)

    Denayer, Jessica; Bister, Geoffroy; Simonis, Priscilla; Colson, Pierre; Maho, Anthony; Aubry, Philippe; Vertruyen, Bénédicte; Henrist, Catherine; Lardot, Véronique; Cambier, Francis; Cloots, Rudi

    2014-12-01

    Lithium-doped nickel oxide and undoped nickel oxide thin films have been deposited on FTO/glass substrates by a surfactant-assisted ultrasonic spray pyrolysis. The addition of polyethylene glycol in the sprayed solution has led to improved uniformity and reduced light scattering compared to films made without surfactant. Furthermore, the presence of lithium ions in NiO films has resulted in improved electrochromic performances (coloration contrast and efficiency), but with a slight decrease of the electrochromic switching kinetics.

  8. Effect of Dummy Block Shape on Deformation of Oxide Film of Billet in Copper Extrusion

    NASA Astrophysics Data System (ADS)

    Uemura, Y.; Hoshino, M.

    2010-06-01

    There are some problems in the copper hot extrusion. One is the mixture of impurities in the product, for example, the oxide film in the side of billet comes to the outer of product and the oxide film in the back-end of billet is inserted in the material and extruded into the center of product, which is called as "piping". Then, it has been investigated that dummy block shape effects on deformation of oxide film by experiment and numerical simulation.

  9. Surfactant assisted Au nanoparticle layering in titanium oxide thin films

    NASA Astrophysics Data System (ADS)

    Mukherjee, Smita; Das, Pradip Shekhar; Choudhuri, Madhumita; Datta, Alokmay; Ghosh, Jiten; Mukhopadhyay, Anoop Kr.

    2017-05-01

    Au Nanoparticle (NP) decorated TiO2 thin films, prepared by a unique surfactant assisted 2D self-assembling technique with molecular level control, showed significant decrease in optical band gap as well as enhanced crystallinity compared to its sol-gel prepared pristine counterpart. Spin coated Au NP overlayers on titania in absence of surfactant, on the other hand, had no appreciable effect on either band gap or crystal structure compared to undoped TiO2 films. Apart from exhibiting band gap tuning of TiO2, this cheap, scalable technique of surfactant aided deposition of 2D layers of Au NPs on semiconducting oxides, may be used for development of multilayered structures with promising light harvesting and unidirectional energy transfer (LUET) applications.

  10. Studies on nickel-tungsten oxide thin films

    SciTech Connect

    Usha, K. S.; Sivakumar, R.; Sanjeeviraja, C.

    2014-10-15

    Nickel-Tungsten oxide (95:5) thin films were prepared by rf sputtering at 200W rf power with various substrate temperatures. X-ray diffraction study reveals the amorphous nature of films. The substrate temperature induced decrease in energy band gap with a maximum transmittance of 71%1 was observed. The Micro-Raman study shows broad peaks at 560 cm{sup −1} and 1100 cm{sup −1} correspond to Ni-O vibration and the peak at 860 cm{sup −1} can be assigned to the vibration of W-O-W bond. Photoluminescence spectra show two peaks centered on 420 nm and 485 nm corresponding to the band edge emission and vacancies created due to the addition of tungsten, respectively.

  11. Microorganism mediated synthesis of reduced graphene oxide films

    NASA Astrophysics Data System (ADS)

    Tanizawa, Y.; Okamoto, Y.; Tsuzuki, K.; Nagao, Y.; Yoshida, N.; Tero, R.; Iwasa, S.; Hiraishi, A.; Suda, Y.; Takikawa, H.; Numano, R.; Okada, H.; Ishikawa, R.; Sandhu, A.

    2012-03-01

    The wide-ranging industrial application of graphene and related compounds has led researchers to devise methods for the synthesis of high quality graphene. We recently reported on the chemical synthesis, patterning, and doping of graphene films by the chemical exfoliation of graphite into graphene oxide (GO) with subsequent chemical reduction into graphene films [1, 2]. Here, we describe a hybrid approach for the synthesis of reduced graphene sheets, where chemically derived GO was reduced by microorganisms extracted from a riverside near the University. Our procedure enabled the production of ~100 μm sized reduced graphene sheets, which showed excellent Raman spectra associated with high quality reduced graphene. We give a detailed account of the relationship between the type of microorganisms and the properties of the resulting reduced graphene.

  12. High angular sensitivity thin film tin oxide sensor

    NASA Astrophysics Data System (ADS)

    Kaur, Davinder; Madaan, Divya; Sharma, V. K.; Kapoor, A.

    2016-05-01

    We present theoretical anlaysis of a thin film SnO2 (Tin Oxide) sensor for the measurement of variation in the refractive index of the bulk media. It is based on lossy mode resonance between the absorbing thin film lossy modes and the evanescent wave. Also the addition of low index dielectric matching layer between the prism and the lossy waveguiding layer future increase the angular sensitivity and produce an efficient refractive index sensor. The angular interrogation is done and obtained sensitivity is 110 degree/RIU. Theoretical analysis of the proposed sensor based on Fresnel reflection coefficients is presented. This enhanced sensitivity will further improve the monitoring of biomolecular interactions and the higher sensitivity of the proposed configurations makes it to be a much better option to be employed for biosensing applications.

  13. Deposition of transparent, conductive tin oxide films on glass using a radio-frequency induction heater

    NASA Astrophysics Data System (ADS)

    Solano, I.; Schwoebel, P. R.

    2009-12-01

    Tin oxide films are often used as transparent, conductive coatings on glass in the scientific research setting. The standard approach of depositing these films in an oven leads to poor visibility of the substrate and thus inhibits the ready formation of uniform, low resistivity films. In this note we describe a simple tin oxide film deposition technique using a radio-frequency induction heater that allows for in situ visualization of the deposition process and resulting film. Uniform films having resistivities as low as 2 mΩ cm with transmittances of approximately 85% in the visible light spectrum were readily deposited.

  14. Growth and Oxidation of Thin Film Al(2)Cu

    SciTech Connect

    SON,KYUNG-AH; MISSERT,NANCY A.; BARBOUR,J. CHARLES; HREN,J.J.; COPELAND,ROBERT GUILD; MINOR,KENNETH G.

    2000-01-18

    Al{sub 2}Cu thin films ({approx} 382 nm) are fabricated by melting and resolidifying Al/Cu bilayers in the presence of a {micro} 3 nm Al{sub 2}O{sub 3} passivating layer. X-ray Photoelectron Spectroscopy (XPS) measures a 1.0 eV shift of the Cu2p{sub 3/2} peak and a 1.6 eV shift of the valence band relative to metallic Cu upon Al{sub 2}Cu formation. Scanning Electron microscopy (SEM) and Electron Back-Scattered Diffraction (EBSD) show that the Al{sub 2}Cu film is composed of 30-70 {micro}m wide and 10-25 mm long cellular grains with (110) orientation. The atomic composition of the film as estimated by Energy Dispersive Spectroscopy (EDS) is 67 {+-} 2% Al and 33 {+-} 2% Cu. XPS scans of Al{sub 2}O{sub 3}/Al{sub 2}Cu taken before and after air exposure indicate that the upper Al{sub 2}Cu layers undergo further oxidation to Al{sub 2}O{sub 3} even in the presence of {approx} 5 nm Al{sub 2}O{sub 3}. The majority of Cu produced from oxidation is believed to migrate below the Al{sub 2}O{sub 3} layers, based upon the lack of evidence for metallic Cu in the XPS scans. In contrast to Al/Cu passivated with Al{sub 2}O{sub 3}, melting/resolidifying the Al/Cu bilayer without Al{sub 2}O{sub 3} results in phase-segregated dendritic film growth.

  15. Hybrid films with graphene oxide and metal nanoparticles could now replace indium tin oxide.

    PubMed

    Varela-Rizo, Helena; Martín-Gullón, Ignacio; Terrones, Mauricio

    2012-06-26

    Graphene oxide (G-O), a highly oxidized sheet of sp(2)-hybridized carbon with insulating electrical properties, can be transformed into graphene if it is adequately reduced. In the past, researchers believed that reduced G-O (rG-O) could be highly conducting, but it has been shown that the presence of extended vacancies and defects within rG-O negatively affect its electrical transport. Although these observations indicated that rG-O could not be used in the fabrication of any electronic device, in this issue of ACS Nano, Ruoff's group demonstrates that rG-O can indeed be used for producing efficient transparent conducting films (TCFs) if the rG-O material is coupled with Au nanoparticles (Au-NPs) and Ag nanowires (Ag-NWs). The work further demonstrates that these hybrid films containing zero-dimensional (Au-NPs), one-dimensional (Ag-NWs), and two-dimensional (rG-O) elements exhibit high optical transmittance (e.g., 90%) and low sheet resistance (20-30 Ω/□), with values comparable to those of indium tin oxide (ITO) films. In addition, Ruoff's group notes that the presence of Ag-NWs and rG-O in the films showed antibacterial properties, thus demonstrating that it is now possible to produce flexible TCFs with bactericidal functions. The data show that smart hybrid films containing rG-O and different types of NPs and NWs could be synthesized easily and could result in smart films with unprecedented functions and applications.

  16. Vibrational spectra of CO adsorbed on oxide thin films: A tool to probe the surface defects and phase changes of oxide thin films

    SciTech Connect

    Savara, Aditya

    2014-03-15

    Thin films of iron oxide were grown on Pt(111) single crystals using cycles of physical vapor deposition of iron followed by oxidative annealing in an ultrahigh vacuum apparatus. Two procedures were utilized for film growth of ∼15–30 ML thick films, where both procedures involved sequential deposition+oxidation cycles. In procedure 1, the iron oxide film was fully grown via sequential deposition+oxidation cycles, and then the fully grown film was exposed to a CO flux equivalent to 8 × 10{sup −7} millibars, and a vibrational spectrum of adsorbed CO was obtained using infrared reflection-absorption spectroscopy. The vibrational spectra of adsorbed CO from multiple preparations using procedure 1 show changes in the film termination structure and/or chemical nature of the surface defects—some of which are correlated with another phase that forms (“phase B”), even before enough of phase B has formed to be easily detected using low energy electron diffraction (LEED). During procedure 2, CO vibrational spectra were obtained between deposition+oxidation cycles, and these spectra show that the film termination structure and/or chemical nature of the surface defects changed as a function of sequential deposition+oxidation cycles. The authors conclude that measurement of vibrational spectra of adsorbed CO on oxide thin films provides a sensitive tool to probe chemical changes of defects on the surface and can thus complement LEED techniques by probing changes not visible by LEED. Increased use of vibrational spectra of adsorbed CO on thin films would enable better comparisons between films grown with different procedures and by different groups.

  17. Spin-Coated vs. Electrodeposited Mn Oxide Films as Water Oxidation Catalysts

    PubMed Central

    Hernández, Simelys; Ottone, Carminna; Varetti, Sara; Fontana, Marco; Pugliese, Diego; Saracco, Guido; Bonelli, Barbara; Armandi, Marco

    2016-01-01

    Manganese oxides (MnOx), being active, inexpensive and low-toxicity materials, are considered promising water oxidation catalysts (WOCs). This work reports the preparation and the physico-chemical and electrochemical characterization of spin-coated (SC) films of commercial Mn2O3, Mn3O4 and MnO2 powders. Spin coating consists of few preparation steps and employs green chemicals (i.e., ethanol, acetic acid, polyethylene oxide and water). To the best of our knowledge, this is the first time SC has been used for the preparation of stable powder-based WOCs electrodes. For comparison, MnOx films were also prepared by means of electrodeposition (ED) and tested under the same conditions, at neutral pH. Particular interest was given to α-Mn2O3-based films, since Mn (III) species play a crucial role in the electrocatalytic oxidation of water. To this end, MnO2-based SC and ED films were calcined at 500 °C, in order to obtain the desired α-Mn2O3 crystalline phase. Electrochemical impedance spectroscopy (EIS) measurements were performed to study both electrode charge transport properties and electrode–electrolyte charge transfer kinetics. Long-term stability tests and oxygen/hydrogen evolution measurements were also made on the highest-performing samples and their faradaic efficiencies were quantified, with results higher than 95% for the Mn2O3 SC film, finally showing that the SC technique proposed here is a simple and reliable method to study the electrocatalytic behavior of pre-synthesized WOCs powders. PMID:28773419

  18. Stress generation in thermally grown oxide films. [oxide scale spalling from superalloy substrates

    NASA Technical Reports Server (NTRS)

    Kumnick, A. J.; Ebert, L. J.

    1981-01-01

    A three dimensional finite element analysis was conducted, using the ANSYS computer program, of the stress state in a thin oxide film thermally formed on a rectangular piece of NiCrAl alloy. The analytical results indicate a very high compressive stress in the lateral directions of the film (approximately 6200 MPa), and tensile stresses in the metal substrate that ranged from essentially zero to about 55 MPa. It was found further that the intensity of the analytically determined average stresses could be approximated reasonably well by the modification of an equation developed previously by Oxx for stresses induced into bodies by thermal gradients.

  19. Oxide nucleation on thin films of copper during in situ oxidation in an electron microscope

    NASA Technical Reports Server (NTRS)

    Heinemann, K.; Rao, D. B.; Douglass, D. L.

    1975-01-01

    Single-crystal copper thin films were oxidized at an isothermal temperature of 425 C and at an oxygen partial pressure of 0.005 torr. Specimens were prepared by epitaxial vapor deposition onto polished faces of rocksalt and were mounted in a hot stage inside the ultrahigh-vacuum chamber of a high-resolution electron microscope. An induction period of roughly 30 min was established which was independent of the film thickness but depended strongly on the oxygen partial pressure and to exposure to oxygen prior to oxidation. Neither stacking faults nor dislocations were found to be associated with the Cu2O nucleation sites. The experimental data, including results from oxygen dissolution experiments and from repetitive oxidation-reduction-oxidation sequences, fit well into the framework of an oxidation process involving the formation of a surface charge layer, oxygen saturation of the metal with formation of a supersaturated zone near the surface, and nucleation followed by surface diffusion of oxygen and bulk diffusion of copper for lateral and vertical oxide growth, respectively.

  20. Oxide nucleation on thin films of copper during in situ oxidation in an electron microscope

    NASA Technical Reports Server (NTRS)

    Heinemann, K.; Rao, D. B.; Douglass, D. L.

    1975-01-01

    Single-crystal copper thin films were oxidized at an isothermal temperature of 425 C and at an oxygen partial pressure of 0.005 torr. Specimens were prepared by epitaxial vapor deposition onto polished faces of rocksalt and were mounted in a hot stage inside the ultrahigh-vacuum chamber of a high-resolution electron microscope. An induction period of roughly 30 min was established which was independent of the film thickness but depended strongly on the oxygen partial pressure and to exposure to oxygen prior to oxidation. Neither stacking faults nor dislocations were found to be associated with the Cu2O nucleation sites. The experimental data, including results from oxygen dissolution experiments and from repetitive oxidation-reduction-oxidation sequences, fit well into the framework of an oxidation process involving the formation of a surface charge layer, oxygen saturation of the metal with formation of a supersaturated zone near the surface, and nucleation followed by surface diffusion of oxygen and bulk diffusion of copper for lateral and vertical oxide growth, respectively.

  1. Modelling the structure of disordered cerium oxide thin films

    NASA Astrophysics Data System (ADS)

    Peña Leal, José Juan; Barrio, Rafael A.

    2017-10-01

    Cerium oxide is an interesting mixed valence compound of great technological importance. We model the growth of thin films of this substance by describing the statistical nucleation of atomic units containing Ce3+ and Ce4+. The theoretical results are compared with available experimental values of the magnetic susceptibility of the material, which is related to the proportion of magnetic atoms in the solid. The model is able to predict the composition of the final solid under different preparation conditions, namely the oxygen content of the precursor and the temperature of the substrate.

  2. Anodic Oxidation in Aluminum Electrode by Using Hydrated Amorphous Aluminum Oxide Film as Solid Electrolyte under High Electric Field.

    PubMed

    Yao, Manwen; Chen, Jianwen; Su, Zhen; Peng, Yong; Zou, Pei; Yao, Xi

    2016-05-04

    Dense and nonporous amorphous aluminum oxide (AmAO) film was deposited onto platinized silicon substrate by sol-gel and spin coating technology. The evaporated aluminum film was deposited onto the AmAO film as top electrode. The hydrated AmAO film was utilized as a solid electrolyte for anodic oxidation of the aluminum electrode (Al) film under high electric field. The hydrated AmAO film was a high efficiency electrolyte, where a 45 nm thick Al film was anodized completely on a 210 nm thick hydrated AmAO film. The current-voltage (I-V) characteristics and breakdown phenomena of a dry and hydrated 210 nm thick AmAO film with a 150 nm thick Al electrode pad were studied in this work. Breakdown voltage of the dry and hydrated 210 nm thick AmAO film were 85 ± 3 V (405 ± 14 MV m(-1)) and 160 ± 5 V (762 ± 24 MV m(-1)), respectively. The breakdown voltage of the hydrated AmAO film increased about twice, owing to the self-healing behavior (anodic oxidation reaction). As an intuitive phenomenon of the self-healing behavior, priority anodic oxidation phenomena was observed in a 210 nm thick hydrated AmAO film with a 65 nm thick Al electrode pad. The results suggested that self-healing behavior (anodic oxidation reaction) was occurring nearby the defect regions of the films during I-V test. It was an effective electrical self-healing method, which would be able to extend to many other simple and complex oxide dielectrics and various composite structures.

  3. Boron-doped cobalt oxide thin films and its electrochemical properties

    NASA Astrophysics Data System (ADS)

    Kerli, S.

    2016-09-01

    The cobalt oxide and boron-doped cobalt oxide thin films were produced by spray deposition method. All films were obtained onto glass and fluorine-doped tin oxide (FTO) substrates at 400∘C and annealed at 550∘C. We present detailed analysis of the morphological and optical properties of films. XRD results show that boron doping disrupts the structure of the films. Morphologies of the films were investigated by using a scanning electron microscopy (SEM). Optical measurements indicate that the band gap energies of the films change with boron concentrations. The electrochemical supercapacitor performance test has been studied in aqueous 6 M KOH electrolyte and with scan rate of 5 mV/s. Measurements show that the largest capacitance is obtained for 3% boron-doped cobalt oxide film.

  4. The effect of temperature on the properties of grapheme oxide langmuir films

    NASA Astrophysics Data System (ADS)

    Seliverstova, E.; Ibrayev, N.; Dzhanabekova, R.; Gladkova, V.

    2017-01-01

    The effect of temperature on the optical properties and structure of graphene oxide langmuir films was studied. It is shown that the decrease of optical density of the films in the absorption band of graphene oxide take place when the film was heated above 100 °C. Increasing the temperature of the films over 200 °C leads to the growth of its optical density. As it was shown with the scanning electron microscopy the structure of grapheme oxide films annealed at different temperatures is practically unchanged. Measured the Raman spectra show that in the films there are a partial reducing of disordered and high-defective graphene oxide LB films occurs under heat treatment. This process accompanied by ordering of amorphous sp3 clusters and its transition in sp2-bonded carbon clusters.

  5. Ozonated graphene oxide film as a proton-exchange membrane.

    PubMed

    Gao, Wei; Wu, Gang; Janicke, Michael T; Cullen, David A; Mukundan, Rangachary; Baldwin, Jon K; Brosha, Eric L; Galande, Charudatta; Ajayan, Pulickel M; More, Karren L; Dattelbaum, Andrew M; Zelenay, Piotr

    2014-04-01

    Graphene oxide (GO) contains several chemical functional groups that are attached to the graphite basal plane and can be manipulated to tailor GO for specific applications. It is now revealed that the reaction of GO with ozone results in a high level of oxidation, which leads to significantly improved ionic (protonic) conductivity of the GO. Freestanding ozonated GO films were synthesized and used as efficient polymer electrolyte fuel cell membranes. The increase in protonic conductivity of the ozonated GO originates from enhanced proton hopping, which is due to the higher content of oxygenated functional groups in the basal planes and edges of ozonated GO as well as the morphology changes in GO that are caused by ozonation. The results of this study demonstrate that the modification of dispersed GO presents a powerful opportunity for optimizing a nanoscale material for proton-exchange membranes.

  6. Thermally evaporated mechanically hard tin oxide thin films for opto-electronic apllications

    NASA Astrophysics Data System (ADS)

    Tripathy, Sumanta K.; Rajeswari, V. P.

    2014-01-01

    Tungsten doped tin oxide (WTO) and Molybdenum doped tin oxide (MoTO) thin film were deposited on corn glass by thermal evaporation method. The films were annealed at 350°C for one hour. Structural analysis using Xray diffraction data shows both the films are polycrystalline in nature with monoclinic structure of tin oxide, Sn3O4, corresponding to JCPDS card number 01-078-6064. SEM photograph showed that both the films have spherical grains with size in the range of 20-30 nm. Compositional analysis was carried out using EDS which reveals the presence of Sn, O and the dopant Mo/W only thereby indicating the absence of any secondary phase in the films. The films are found to contain nearly 6 wt% of Mo, 8 wt% of W as dopants respectively. The transmission pattern for both the films in the spectral range 200 - 2000 nm shows that W doping gives a transparency of nearly 80% from 380 nm onwards while Mo doping has less transparency of 39% at 380nm. Film hardness measurement using Triboscope shows a film hardness of about 9-10 GPa for both the films. It indicates that W or M doping in tin oxide provides the films the added advantage of withstanding the mechanical wear and tear due to environmental fluctuations By optimizing the optical and electrical properties, W/Mo doped tin oxide films may be explored as window layers in opto-electronic applications such as solar cells.

  7. Improving electrical properties of sol-gel derived zinc oxide thin films by plasma treatment

    NASA Astrophysics Data System (ADS)

    Talukder, Al-Ahsan; Pokharel, Jyotshna; Shrestha, Maheshwar; Fan, Qi H.

    2016-10-01

    Being a direct and wide bandgap semiconductor, zinc oxide is a suitable material for various optoelectronic applications. These applications require tuning and controlling over the electrical and optical properties of zinc oxide films. In this work, zinc oxide thin films were prepared by a solution method that led to oriented crystal growth along (002) plane. The zinc oxide thin films were treated with oxygen, hydrogen, and nitrogen plasmas. The films were characterized to reveal the effects of plasma treatments on transmittance, crystallinity, carrier density, carrier mobility, and electrical resistivity. Oxygen plasma treatment improved the crystallinity of the zinc oxide thin film without affecting the film's transmittance. Hydrogen plasma treatments were found very effective in improving the electrical conductivity sacrificing the film's transmittance. Nitrogen plasma treatment led to improved electrical conductivity without compromising the crystallinity and optical transmittance. Sequential oxygen, hydrogen, and nitrogen plasma treatments significantly reduced the resistivity of zinc oxide thin films by over two orders and maintained the transmittance close to the as-deposited films of ˜80% in visible wavelength range. This is the first work on the improvement of conductivity of solution-based zinc oxide films using the plasma treatment.

  8. Effect of Oxidation Condition on Growth of N: ZnO Prepared by Oxidizing Sputtering Zn-N Film.

    PubMed

    Qin, Xuesi; Li, Guojian; Xiao, Lin; Chen, Guozhen; Wang, Kai; Wang, Qiang

    2016-12-01

    Nitrogen-doped zinc oxide (N: ZnO) films have been prepared by oxidizing reactive RF magnetron-sputtering zinc nitride (Zn-N) films. The effect of oxidation temperature and oxidation time on the growth, transmittance, and electrical properties of the film has been explored. The results show that both long oxidation time and high oxidation temperature can obtain the film with a good transmittance (over 80 % for visible and infrared light) and a high carrier concentration. The N: ZnO film exhibits a special growth model with the oxidation time and is first to form a N: ZnO particle on the surface, then to become a N: ZnO layer, and followed by the inside Zn-N segregating to the surface to oxidize N: ZnO. The surface particle oxidized more adequately than the inside. However, the X-ray photoemission spectroscopy results show that the lower N concentration results in the lower N substitution in the O lattice (No). This leads to the formation of n-type N: ZnO and the decrease of carrier concentration. Thus, this method can be used to tune the microstructure, optical transmittance, and electrical properties of the N: ZnO film.

  9. Formation of Flexible and Transparent Indium Gallium Zinc Oxide/Ag/Indium Gallium Zinc Oxide Multilayer Film

    NASA Astrophysics Data System (ADS)

    Kim, Jun Ho; Kim, Da-Som; Kim, Sun-Kyung; Yoo, Young-Zo; Lee, Jeong Hwan; Kim, Sang-Woo; Seong, Tae-Yeon

    2016-08-01

    In this study, the electrical, optical, and bending characteristics of amorphous indium gallium zinc oxide (IGZO)/Ag/IGZO (39 nm/19 nm/39 nm) multilayer films deposited on polyethylene terephthalate (PET) substrate at room temperature were investigated and compared with those of Sn-doped indium oxide (ITO) (100 nm thick) films. At 500 nm the ITO film transmitted 91.3% and the IGZO/Ag/IGZO multilayer film transmitted 88.8%. The calculated transmittance spectrum of the multilayer film was similar to the experimental result. The ITO film and IGZO/Ag/IGZO multilayer film, respectively, showed carrier concentrations of 1.79 × 1020 and 7.68 × 1021 cm-3 and mobilities of 27.18 cm2/V s and 18.17 cm2/V s. The ITO film had a sheet resistance of 134.9 Ω/sq and the IGZO/Ag/IGZO multilayer film one of 5.09 Ω/sq. Haacke's figure of merit (FOM) was calculated to be 1.94 × 10-3 for the ITO film and 45.02 × 10-3 Ω-1 for the IGZO/Ag/IGZO multilayer film. The resistance change of 100 nm-thick ITO film was unstable even after five cycles, while that of the IGZO/Ag/IGZO film was constant up to 1000 cycles.

  10. Amorphous semiconducting and conducting transparent metal oxide thin films and production thereof

    DOEpatents

    Perkins, John; Van Hest, Marinus Franciscus Antonius Maria; Ginley, David; Taylor, Matthew; Neuman, George A.; Luten, Henry A.; Forgette, Jeffrey A.; Anderson, John S.

    2010-07-13

    Metal oxide thin films and production thereof are disclosed. An exemplary method of producing a metal oxide thin film may comprise introducing at least two metallic elements and oxygen into a process chamber to form a metal oxide. The method may also comprise depositing the metal oxide on a substrate in the process chamber. The method may also comprise simultaneously controlling a ratio of the at least two metallic elements and a stoichiometry of the oxygen during deposition. Exemplary amorphous metal oxide thin films produced according to the methods herein may exhibit highly transparent properties, highly conductive properties, and/or other opto-electronic properties.

  11. Properties of mixed molybdenum oxide iridium oxide thin films synthesized by spray pyrolysis

    NASA Astrophysics Data System (ADS)

    Patil, P. S.; Kawar, R. K.; Sadale, S. B.; Inamdar, A. I.; Deshmukh, H. P.

    2006-09-01

    Molybdenum-doped iridium oxide thin films have been deposited onto corning glass- and fluorine-doped tin oxide coated corning glass substrates at 350 °C by using a pneumatic spray pyrolysis technique. An aqueous solution of 0.01 M ammonium molybdate was mixed with 0.01 M iridium trichloride solution in different volume proportions and the resultant solution was used as a precursor solution for spraying. The as-deposited samples were annealed at 600 °C in air medium for 1 h. The structural, electrical and optical properties of as-deposited and annealed Mo-doped iridium oxide were studied and values of room temperature electrical resistivity, and thermoelectric power were estimated. The as-deposited samples with 2% Mo doping exhibit more pronounced electrochromism than other samples, including pristine Ir oxide.

  12. Oxidation Effect in Octahedral Hafnium Disulfide Thin Film.

    PubMed

    Chae, Sang Hoon; Jin, Youngjo; Kim, Tae Soo; Chung, Dong Seob; Na, Hyunyeong; Nam, Honggi; Kim, Hyun; Perello, David J; Jeong, Hye Yun; Ly, Thuc Hue; Lee, Young Hee

    2016-01-26

    Atomically smooth van der Waals materials are structurally stable in a monolayer and a few layers but are susceptible to oxygen-rich environments. In particular, recently emerging materials such as black phosphorus and perovskite have revealed stronger environmental sensitivity than other two-dimensional layered materials, often obscuring the interesting intrinsic electronic and optical properties. Unleashing the true potential of these materials requires oxidation-free sample preparation that protects thin flakes from air exposure. Here, we fabricated few-layer hafnium disulfide (HfS2) field effect transistors (FETs) using an integrated vacuum cluster system and study their electronic properties and stability under ambient conditions. By performing all the device fabrication and characterization procedure under an oxygen- and moisture-free environment, we found that few-layer AA-stacking HfS2-FETs display excellent field effect responses (Ion/Ioff ≈ 10(7)) with reduced hysteresis compared to the FETs prepared under ambient conditions. Oxidation of HfS2 occurs uniformly over the entire area, increasing the film thickness by 250% at a prolonged oxidation time of >120 h, while defects on the surface are the preferential initial oxidation sites. We further demonstrated that the stability of the device in air is significantly improved by passivating FETs with BN in a vacuum cluster.

  13. Growth of Ordered Ultrathin Tungsten Oxide Films on Pt(111)

    SciTech Connect

    Li, Zhenjun; Zhang, Zhenrong; Kim, Yu Kwon; Smith, R. Scott; Netzer, Falko; Kay, Bruce D.; Rousseau, Roger J.; Dohnalek, Zdenek

    2011-04-07

    Ordered tungsten oxide ultra-thin films were prepared on a Pt(111) substrate at 700 K via direct sublimation of monodispersed cyclic (WO3)3 trimers. The surface composition, structure and morphology were determined using a combination of atomically resolved imaging, ensemble-averaged surface-sensitive spectroscopies, and density functional theory (DFT). We find that half of the (WO3)3 tungsten atoms get partially reduced to the (5+) oxidation state in the first layer at the Pt(111) interface. The opening of the (WO3)3 ring leads to the formation of a tungsten oxide layer with a zig-zag chain structure with a c(4×2) periodicity. In the second layer, the (WO3)3 clusters remain intact and form an ordered (3×3) array of molecularly-bound (WO3)3. DFT calculations provide a detailed understanding of the structure, oxidation states, and the vibrational frequencies for both the c(4×2) and (3×3) overlayers.

  14. Energy dissipation of highly charged ions on Al oxide films.

    PubMed

    Lake, R E; Pomeroy, J M; Sosolik, C E

    2010-03-03

    Slow highly charged ions (HCIs) carry a large amount of potential energy that can be dissipated within femtoseconds upon interaction with a surface. HCI-insulator collisions result in high sputter yields and surface nanofeature creation due to strong coupling between the solid's electronic system and lattice. For HCIs interacting with Al oxide, combined experiments and theory indicate that defect mediated desorption can explain reasonably well preferential O atom removal and an observed threshold for sputtering due to potential energy. These studies have relied on measuring mass loss on the target substrate or probing craters left after desorption. Our approach is to extract highly charged ions onto the Al oxide barriers of metal-insulator-metal tunnel junctions and measure the increased conductance in a finished device after the irradiated interface is buried under the top metal layer. Such transport measurements constrain dynamic surface processes and provide large sets of statistics concerning the way individual HCI projectiles dissipate their potential energy. Results for Xe(q +) for q = 32, 40, 44 extracted onto Al oxide films are discussed in terms of postirradiation electrical device characteristics. Future work will elucidate the relationship between potential energy dissipation and tunneling phenomena through HCI modified oxides.

  15. Cobalt deposition in oxide films on reactor pipework. Final report

    SciTech Connect

    Bridle, D.A.; Bird, E.J.; Mitchell, C.R.

    1986-03-01

    This report details results of a program carried out by the UKAEA on the Winfrith SGHWR, to study the incorporation of cobalt into the corrosion product films formed on PWR primary circuit materials (stainless steel 304L, Inconel-600 and Zircaloy-4). An electromagnetic filter has been operated on a once through basis directly on the primary coolant blowdown line to remove particulate impurities. This has permitted an examination of the relative importance of soluble and insoluble species in the formation of corrosion product films. The selected alloys have been exposed to coolant up and downstream from the filter unit and data are presented which provide a detailed analysis of the coolant at these situations, with respect to soluble and insoluble, chemical and radiochemical species. Characterization of the corrosion product films has been carried out using scanning electron microscopy coupled with energy dispersive analysis using x-rays. Radiochemical analyses have been carried out using ..gamma..-spectrometry. The effectiveness of decontamination using Low Oxidation state Metal Ion (LOMI) reagent has been studied and data are presented on decontamination rates. 21 tabs.

  16. Modification of Silicon Oxide Surfaces with Thermally Annealed Polystyrene Films

    NASA Astrophysics Data System (ADS)

    Kalan, Steven; Cavicchi, Kevin; Karim, Alamgir

    2011-03-01

    The modification of silicon with a native oxide surface has been accomplished by annealing thin films of anionically polymerized polystyrene spun-coat from solution at elevated temperature followed by dissolving the film in solvent to leave a thin layer of adsorbed polymer that persisted even after prolonged desorbing in solvent even at elevated temperature. It was found by water contact angle analysis of the samples after washing with organic solvent that annealing is a key step to adsorption of a thin layer of polystyrene on the film surface. X-ray reflectivity analysis also demonstrated that the thickness of the adsorbed layer is proportional to the molecular weight of the polymer. However, the contact angle showed a non-monotonic dependence on molecular weight. The further modification of these surfaces by ultraviolet/ozone treatment will be discussed. This is a novel surface treatment method as it performed with a polystyrene polymer without any additional chemical functionality through straight-forward vacuum annealing and washing with organic solvent.

  17. Biopolymer-modified graphite oxide nanocomposite films based on benzalkonium chloride-heparin intercalated in graphite oxide

    NASA Astrophysics Data System (ADS)

    Meng, Na; Zhang, Shuang-Quan; Zhou, Ning-Lin; Shen, Jian

    2010-05-01

    Heparin is a potent anticoagulant agent that interacts strongly with antithrombin III to prevent the formation of fibrin clots. In the present work, poly(dimethylsiloxane)(PDMS)/graphite oxide-benzalkonium chloride-heparin (PDMS/modified graphite oxide) nanocomposite films were obtained by the solution intercalation technique as a possible drug delivery system. The heparin-benzalkonium chloride (BAC-HEP) was intercalated into graphite oxide (GO) layers to form GO-BAC-HEP (modified graphite oxide). Nanocomposite films were characterized by XRD, SEM, TEM, ATR-FTIR and TGA. The modified graphite oxide was observed to be homogeneously dispersed throughout the PDMS matrix. The effect of modified graphite oxide on the mechanical properties of the nanocomposite film was investigated. When the modified graphite oxide content was lower than 0.2 wt%, the nanocomposites showed excellent mechanical properties. Furthermore, nanocomposite films become delivery systems that release heparin slowly to make the nanocomposite films blood compatible. The in vitro studies included hemocompatibility testing for effects on platelet adhesion, platelet activation, plasma recalcification profiles, and hemolysis. Results from these studies showed that the anticoagulation properties of PDMS/GO-BCA-HEP nanocomposite films were greatly superior to those for no treated PDMS. Cell culture assay indicated that PDMS/GO-BCA-HEP nanocomposite films showed enhanced cell adhesion.

  18. Sputtered iridium oxide films (SIROFs) for neural stimulation electrodes

    PubMed Central

    Cogan, Stuart F.; Ehrlich, Julia; Plante, Timothy D.; Smirnov, Anton; Shire, Douglas B.; Gingerich, Marcus; Rizzo, Joseph F.

    2009-01-01

    Sputtered iridium oxide films (SIROFs) deposited by DC reactive sputtering from an iridium metal target have been characterized in vitro for their potential as neural recording and stimulation electrodes. SIROFs were deposited over gold metallization on flexible multielectrode arrays fabricated on thin (15 µm) polyimide substrates. SIROF thickness and electrode areas of 200–1300 nm and 1960–125600 µm2, respectively, were investigated. The charge-injection capacities of the SIROFs were evaluated in an inorganic interstitial fluid model in response to charge-balanced, cathodal-first current pulses. Charge injection capacities were measured as a function of cathodal pulse width (0.2 – 1 ms) and potential bias in the interpulse period (0.0 to 0.7 V vs. Ag|AgCl). Depending on the pulse parameters and electrode area, charge-injection capacities ranged from 1–9 mC/cm2, comparable with activated iridium oxide films (AIROFs) pulsed under similar conditions. Other parameters relevant to the use of SIROF on nerve electrodes, including the thickness dependence of impedance (0.05–105 Hz) and the current necessary to maintain a bias in the interpulse region were also determined. PMID:17271216

  19. Interactions at Metal/oxide and Oxide/oxide Interfaces Studied by Ultrathin Film Growth on Single-Crystal Oxide Substrates

    NASA Astrophysics Data System (ADS)

    Lad, Robert J.

    This article reviews aspects of the electronic, chemical, and structural properties of metal/oxide and oxide/oxide interfaces which are formed via ultrathin film growth on oxide single-crystal surfaces. The interactions at the interfaces are classified based on the nature of the reaction products, thermodynamic predictions of interfacial reactions, and wetting and adhesion. Then, properties of single-crystal oxide substrates and limitations and difficulties in studying these ceramic systems are discussed. The remainder of the article presents experimental observations for several systems involving both metal and oxide ultrathin film growth on stoichiometric NiO(100), TiO2(110), and α - Al2 O3 (10bar {1} 2) surfaces including a discussion of interdiffusion, chemical and electronic interactions, thermal stability, and interfacial impurity effects.

  20. Single cuprous oxide films synthesized by radical oxidation at low temperature for PV application.

    PubMed

    Zang, Zhigang; Nakamura, Atsushi; Temmyo, Jiro

    2013-05-06

    Cuprous oxide (Cu(2)O) films synthesis by radical oxidation with nitrogen (N(2)) plasma treatment and different RF power at low temperature (500 °C) are studied in this paper. X-ray diffraction measurements show that synthesized Cu(2)O thin films grow on c-sapphire substrate with preferred (111) orientation. With nitrogen (N(2)) plasma treatment, the optical bandgap energy is increased from 1.69 to 2.42 eV, when N(2) plasma treatment time is increased from 0 min to 40 min. Although the hole density is increased from 10(14) to 10(15) cm(-3) and the resistivity is decreased from 1879 to 780 Ω cm after N(2) plasma treatment, the performance of Cu(2)O films is poorer compared to that of Cu(2)O using RF power of 0. The fabricated ZnO/Cu(2)O solar cells based on Cu(2)O films with RF power of 0 W show a good rectifying behavior with a efficiency of 0.02%, an open-circuit voltage of 0.1 V, and a fill factor of 24%.

  1. Amperometric detection and electrochemical oxidation of aliphatic amines and ammonia on silver-lead oxide thin-film electrodes

    SciTech Connect

    Ge, Jisheng

    1996-01-08

    This thesis comprises three parts: Electrocatalysis of anodic oxygen-transfer reactions: aliphatic amines at mixed Ag-Pb oxide thin-film electrodes; oxidation of ammonia at anodized Ag-Pb eutectic alloy electrodes; and temperature effects on oxidation of ethylamine, alanine, and aquated ammonia.

  2. Electrical Conductivity of Tin Oxide Films in Ethanol Atmosphere

    NASA Astrophysics Data System (ADS)

    Park, Sung-Soon

    1995-01-01

    Porous ultrafine SnO_2 -based ethanol gas sensors in the shape of a thin film were successfully fabricated from tin alkoxide by the sol-gel dip coating technique. For the first time, the influences of film thickness, microstructure, and additives on the ethanol gas sensing properties of the sol-gel derived SnO _2 thin films were investigated. The equilibrium density of ionosorbed oxygens seemed to be maximum at 300^circC. This seemed to be the reason the sensitivity was maximum at 300^circC. Theoretically it was expected that the sensitivity would increase monotonically with decreasing the thickness, but the results were totally different from the prediction below the thickness of 700 A. The sensitivity increased down to the thickness of 700 A, but below 700 A it suddenly decreased. The sudden decrease seemed to be due to the sudden decrease of porosity, that is, the sudden decrease of the surface area for the oxidation reaction of rm C_2H_5 OH. Thus, it seemed that below 700 A, the sensitivity was governed by the microstructure, that is, porosity (surface area) rather than the thickness. The sensitivity was markedly increased by loading with rm La_2O _3 and Pt. The increased response time caused by loading with rm La_2O_3 was completely removed by loading with Pt. On the other hand, the sensitivity decreased with increasing relative humidity. The reason for this and the methods to decrease the humidity effect will be discussed. However, the Pt-La_2O_3-SnO _2 thin film sensors had strong dependence of the sensitivity on ethanol concentration, and the sensitivity at 70 ppm rm C_2H_5OH was as high as 28, being sensitive enough to be a breath alcohol checker and a monitor for alcohol vapor in air.

  3. Periodic oxidation for fabricating titanium oxynitride thin films via atomic layer deposition

    SciTech Connect

    Iwashita, Shinya Aoyama, Shintaro; Nasu, Masayuki; Shimomura, Kouji; Noro, Naotaka; Hasegawa, Toshio; Akasaka, Yasushi; Miyashita, Kohei

    2016-01-15

    This paper demonstrates thermal atomic layer deposition (ALD) combined with periodic oxidation for synthesizing titanium oxynitride (TiON) thin films. The process used a typical ALD reactor for the synthesis of titanium nitride (TiN) films wherein oxygen was supplied periodically between the ALD-TiN cycles. The great advantage of the process proposed here was that it allowed the TiN films to be oxidized efficiently. Also, a uniform depth profile of the oxygen concentration in the films could be obtained by tuning the oxidation conditions, allowing the process to produce a wide variety of TiON films. The resistivity measurement is a convenient method to confirm the reproducibility of metal film fabrication but may not be applicable for TiON films depending upon the oxidation condition because the films can easily turn into insulators when subjected to periodic oxidation. Therefore, an alternative reproducibility confirmation method was required. In this study, spectroscopic ellipsometry was applied to monitor the variation of TiON films and was able to detect changes in film structures such as conductor–insulator transitions in the TiON films.

  4. Solution processed metal oxide thin film hole transport layers for high performance organic solar cells

    DOEpatents

    Steirer, K. Xerxes; Berry, Joseph J.; Chesin, Jordan P.; Lloyd, Matthew T.; Widjonarko, Nicodemus Edwin; Miedaner, Alexander; Curtis, Calvin J.; Ginley, David S.; Olson, Dana C.

    2017-01-10

    A method for the application of solution processed metal oxide hole transport layers in organic photovoltaic devices and related organic electronics devices is disclosed. The metal oxide may be derived from a metal-organic precursor enabling solution processing of an amorphous, p-type metal oxide. An organic photovoltaic device having solution processed, metal oxide, thin-film hole transport layer.

  5. Comment on "Tunable Design of Structural Colors Produced by Pseudo-1D Photonic Crystals of Graphene Oxide" and Thin-Film Interference from Dried Graphene Oxide Film.

    PubMed

    Hong, Seung-Ho; Song, Jang-Kun

    2017-04-01

    The mechanism of the iridescent color reflection from dried thin graphene oxide (GO) film on Si wafer is clarified. Dissimilarly to the photonic crystalline reflection in aqueous GO dispersion, the color reflection in dried GO film originates from the thin film interference. The peak reflection can reach 23% by optimizing the GO thickness and the substrate. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Epitaxial Growth of Intermetallic MnPt Films on Oxides and Large Exchange Bias

    SciTech Connect

    Liu, Zhiqi; Biegalski, Michael D; Hsu, Mr. S. L.; Shang, Dr. Shunli; Marker, Cassie; Liu, Jian; Li, Li; Fan, Lisha; Meyer, Tricia L; Wong, Anthony T; Nichols, John A; Chen, Deyang; You, Long; Chen, Zuhuang; Wang, Kai; Wang, Kevin; Ward, Thomas Zac; Gai, Zheng; Lee, Ho Nyung; Sefat, Athena Safa; Lauter, Valeria; Liu, Zi-Kui; Christen, Hans M.

    2015-11-05

    We achieved a high-quality epitaxial growth of inter­metallic MnPt films on oxides, with potential for multiferroic heterostructure applications. Also, antisite-stabilized spin-flipping induces ferromagnetism in MnPt films, although it is robustly antiferromagnetic in bulk. Moreover, highly ordered antiferromagnetic MnPt films exhibit superiorly large exchange coupling with a ferromagnetic layer.

  7. Amorphous thin film ruthenium oxide as an electrode material for electrochemical capacitors

    SciTech Connect

    Jow, T.R.; Zheng, J.P.

    1995-12-31

    Ruthenium oxide thin films of an amorphous phase were successfully prepared on a titanium (Ti) substrate at temperatures below 160 C. The sol-gel process using metal alkoxide precursor in nonaqueous solvents was used to prepare these films. The preliminary results showed that a specific capacitance of 430 F/g can be achieved for amorphous ruthenium oxide electrode in sulfuric acid. Films prepared by this method are compared with the films prepared by the thermal decomposition of the aqueous ruthenium chloride solution at temperatures above 300 C. The specific capacitance, the crystalline structure, and the surface morphology of these films as a function of the preparation temperature were also discussed.

  8. Doped, porous iron oxide films and their optical functions and anodic photocurrents for solar water splitting

    SciTech Connect

    Kronawitter, Coleman X.; Mao, Samuel S.; Antoun, Bonnie R.

    2011-02-28

    The fabrication and morphological, optical, and photoelectrochemical characterization of doped iron oxide films is presented. The complex index of refraction and absorption coefficient of polycrystalline films are determined through measurement and modeling of spectral transmission and reflection data using appropriate dispersion relations. Photoelectrochemical characterization for water photo-oxidation reveals that the conversion efficiencies of electrodes are strongly influenced by substrate temperature during their oblique-angle physical vapor deposition. These results are discussed in terms of the films' morphological features and the known optoelectronic limitations of iron oxide films for application in solar water splitting devices.

  9. Structural and physical properties of tin oxide thin films for optoelectronic applications

    NASA Astrophysics Data System (ADS)

    Lin, Su-Shia; Tsai, Yung-Shiang; Bai, Kai-Ren

    2016-09-01

    Tin oxide films were deposited on glass substrates by RF magnetron sputtering. At a lower sputtering pressure, the tin oxide film comprised nanocrystalline orthorhombic SnO with a (110) orientation, greater p-type conductivity and better hydrophobicity. Increasing substrate temperature resulted in the coexistence of nanocrystalline orthorhombic SnO and tetragonal SnO2 in the deposited film, favoring hydrophilicity, changing the p-type conductivity to n-type conductivity, and reducing resistivity. As the sputtering pressure or substrate temperature increased, the tin oxide film exhibited a lower surface roughness, a larger optical energy gap, and higher optical transmission.

  10. Anisotropy and micromagnetics in complex oxide thin films

    NASA Astrophysics Data System (ADS)

    Wynn, Thomas Andrew

    Complex oxide perovskites are a class of material with a remarkably wide range of functional properties including magnetism, superconductivity, metal-to-insulator transitions, colossal magnetoresistance, and in some cases high magnetocrystalline anisotropy. Reduction in length scales through thin film deposition and nanopatterning results in altered properties from their bulk constituents. In this work, thin films of La0.7Sr0.3CoO3 (LSCO) and LSCO/La 0.7Sr0.3MnO3 (LSMO) bilayers of varying thicknesses were deposited onto (LaAlO3)0.3(Sr2TaAlO 6)0.7 (LSAT) substrates, and their anisotropic magnetic properties were measured along the in- plane [100] and [110] directions using superconducting quantum interference device (SQUID) magnetometry and soft x-ray magnetic spectroscopy. The LSCO showed thickness dependent magnetism, and films were non-magnetic below a critical thickness of 4 nm. Magnetic LSCO films showed unique anisotropic effects on the saturation magnetization (Ms), with a lower M s in the [110] direction than the [100] direction. This potentially indicates the existence of a hard component in the [110] direction that is not being switched at fields in the SQUID magnetometer (7 T). Normalized hysteresis loops indicate the LSCO films display little magnetocrystalline anisotropy within the plane of the film. LSCO/LSMO bilayers with a fixed LSMO layer of 6 nm in thickness showed cobalt magnetism at thicknesses where single layers were non-magnetic, suggesting that the substrate/film interface is not the cause of the non-magnetic layer in the LSCO thin films. Magnetic coupling occurs in bilayers with LSCO layer thicknesses of below 4 nm, and both LSCO and LSMO layers showed a [110] easy axis. When the layer thickness of LSCO was increased above 8 nm, the LSCO layer developed a soft component at the LSCO/LSMO interface. This soft LSCO component remained coupled with the LSMO, though the easy axis changed to the [100] direction, and the harder, non-interface LSCO

  11. Reversible transformations of silver oxide and metallic silver nanoparticles inside SiO{sub 2} films

    SciTech Connect

    Pal, Sudipto; De, Goutam

    2009-02-04

    Reversible transformation of silver oxide and metallic nanoparticles inside a relatively porous silica film has been established. Annealing of Ag-doped films in oxidizing (air) atmosphere at 450 deg. C yielded colorless films containing AgO{sub x}. These films were turned yellow when heated in H{sub 2}-N{sub 2} (reducing atmosphere) due to the formation of Ag nanoparticles. This yellow coloration (due to nano Ag{sup 0}) and bleaching (conversion of Ag{sup 0} {yields} Ag{sup +}) are reversible. Optical and photoluminescence spectra are well consistent with this coloration and bleaching. The soaking test of the air-annealed film in Na{sub 2}S{sub 2}O{sub 3} solution supports the presence of Ag{sup +}. Grazing incidence X-ray diffraction and transmission electron microscopy studies reveal the formation of Ag-oxides and Ag nanoparticles in the oxidized and reduced films, respectively.

  12. Growth and Dissolution of Iron and Manganese Oxide Films

    SciTech Connect

    Scot T. Martin

    2008-12-22

    Growth and dissolution of Fe and Mn oxide films are key regulators of the fate and transport of heavy metals in the environment, especially during changing seasonal conditions of pH and dissolved oxygen. The Fe and Mn are present at much higher concentrations than the heavy metals, and, when Fe and Mn precipitate as oxide films, heavy metals surface adsorb or co-precipitate and are thus essentially immobilized. Conversely, when the Fe and Mn oxide films dissolve, the heavy metals are released to aqueous solution and are thus mobilized for transport. Therefore, understanding the dynamics and properties of Fe and Mn oxide films and thus on the uptake and release of heavy metals is critically important to any attempt to develop mechanistic, quantitative models of the fate, transport, and bioavailablity of heavy metals. A primary capability developed in our earlier work was the ability to grow manganese oxide (MnO{sub x}) films on rhodochrosite (MnCO{sub 3}) substrate in presence of dissolved oxygen under mild alkaline conditions. The morphology of the films was characterized using contact-mode atomic force microscopy. The initial growth began by heteroepitaxial nucleation. The resulting films had maximum heights of 1.5 to 2 nm as a result of thermodynamic constraints. Over the three past years, we have investigated the effects of MnO{sub x} growth on the interactions of MnCO{sub 3} with charged ions and microorganisms, as regulated by the surface electrical properties of the mineral. In 2006, we demonstrated that MnO{sub x} growth could induce interfacial repulsion and surface adhesion on the otherwise neutral MnCO{sub 3} substrate under environmental conditions. Using force-volume microscopy (FVM), we measured the interfacial and adhesive forces on a MnO{sub x}/MnCO{sub 3} surface with a negatively charged silicon nitride tip in a 10-mM NaNO3 solution at pH 7.4. The interfacial force and surface adhesion of MnOx were approximately 40 pN and 600 pN, respectively

  13. Flexible Electronics Powered by Mixed Metal Oxide Thin Film Transistors

    NASA Astrophysics Data System (ADS)

    Marrs, Michael

    A low temperature amorphous oxide thin film transistor (TFT) and amorphous silicon PIN diode backplane technology for large area flexible digital x-ray detectors has been developed to create 7.9-in. diagonal backplanes. The critical steps in the evolution of the backplane process include the qualification and optimization of the low temperature (200 °C) metal oxide TFT and a-Si PIN photodiode process, the stability of the devices under forward and reverse bias stress, the transfer of the process to flexible plastic substrates, and the fabrication and assembly of the flexible detectors. Mixed oxide semiconductor TFTs on flexible plastic substrates suffer from performance and stability issues related to the maximum processing temperature limitation of the polymer. A novel device architecture based upon a dual active layer improves both the performance and stability. Devices are directly fabricated below 200 ºC on a polyethylene naphthalate (PEN) substrate using mixed metal oxides of either zinc indium oxide (ZIO) or indium gallium zinc oxide (IGZO) as the active semiconductor. The dual active layer architecture allows for adjustment to the saturation mobility and threshold voltage stability without the requirement of high temperature annealing, which is not compatible with flexible plastic substrates like PEN. The device performance and stability is strongly dependent upon the composition of the mixed metal oxide; this dependency provides a simple route to improving the threshold voltage stability and drive performance. By switching from a single to a dual active layer, the saturation mobility increases from 1.2 cm2/V-s to 18.0 cm2/V-s, while the rate of the threshold voltage shift decreases by an order of magnitude. This approach could assist in enabling the production of devices on flexible substrates using amorphous oxide semiconductors. Low temperature (200°C) processed amorphous silicon photodiodes were developed successfully by balancing the tradeoffs

  14. Measurements of the optical properties of thin films of silver and silver oxide

    NASA Technical Reports Server (NTRS)

    Peters, Palmer N.; Sisk, Robert C.; Brown, Yolanda; Gregory, John C.; Nag, Pallob K.; Christl, Ligia

    1995-01-01

    The optical properties of silver films and their oxides are measured to better characterize such films for use as sensors for atomic oxygen. Good agreement between properties of measured pure silver films and reported optical constants is observed. Similar comparisons for silver oxide have not been possible because of a lack of reported constants, but self-consistencies and discrepancies in our measured results are described.

  15. Fabrication of Fe-Al nanoparticles by selective oxidation of Fe-Al thin films

    NASA Astrophysics Data System (ADS)

    Jang, Pyungwoo; Shin, Seungchan; Jung, Chip-Sup; Kim, Kwang-Ho; Seomoon, Kyu

    2013-04-01

    The possibility of a new technique for fabricating nanoparticles from thin films using selective oxidation in an atmosphere mixture of water vapor and hydrogen was investigated. Fe-5wt.%Al films were RF-sputtered and annealed in the atmosphere mixture at 900°C for up to 200 min, in order to oxidize aluminum selectively. Thermodynamics simulation showed that temperatures exceeding 800°C are necessary to prevent iron from being oxidized, as confirmed by the depth profile of XPS. As the annealing time increased, the morphology of the 200-nm Fe-Al films changed from the continuous to the discontinuous type; thus, particulate Fe-Al films formed after 100 min. The particulate 10- to 100-nm Fe-Al films showed super-paramagnetic behavior after the oxidation. Thus, a new technique for fabricating nanoparticles was successfully introduced using selective oxidation.

  16. Photocatalytic degradation of triethylamine on titanium oxide thin films

    SciTech Connect

    Huang, A.; Cao, L.; Chen, J.; Spiess, F.J.; Suib, S.L.; Obee, T.N.; Hay, S.O.; Freihaut, J.D.

    1999-11-15

    Photooxidation of triethylamine (TEA) in the presence of O{sub 2}, N{sub 2}, and H{sub 2}O over titanium oxide (TiO{sub 2}) was investigated using a flat plate reactor. TEA was photocatalytically oxidized to CO{sub 2} and some by-products on TiO{sub 2} thin film catalysts. The intrinsic oxidation rate of the reaction was determined and was dependent on TEA concentration, humidity level, and light intensity. Photocatalytic deactivation was observed in these reactions. Fourier transform infrared (FTIR) and temperature-programmed desorption with a mass spectrometer as a detector (TPD-MS) were used to characterize the surface of the catalyst and study the deactivation mechanism. FTIR and TPD-MS results suggest that accumulation of carboxylic acid species, -N-N=O, and some other accumulation of carboxylic acid species, -N-N=O, and some other carbonaceous species occurred during the reaction. These by-product species or intermediates were chemisorbed on the catalyst surface. They were stable under reaction conditions and might be responsible for deactivation of TiO{sub 2} by either poisoning the active sites directly or blocking the adsorption of TEA on the catalyst surface.

  17. F2-Laser-Induced Modification of Aluminum Thin Films into Transparent Aluminum Oxide

    NASA Astrophysics Data System (ADS)

    Okoshi, Masayuki; Iwai, Kazufumi; Nojiri, Hidetoshi; Inoue, Narumi

    2012-12-01

    A vacuum-UV F2 laser of 157 nm wavelength induced strong oxidation of 10-nm-thick Al thin films, forming transparent Al2O3 on silica glass. The laser-induced modification occurred at the surface of Al thin films; consequently, the thickness of the formed Al2O3 thin films increased linearly with increasing number of F2 laser photons. The formation of equivalent-phase Al2O3 thin films was confirmed by X-ray photoelectron spectroscopy. The oxidation reaction in the laser-induced modification of 10-nm-thick Al thin films was slower than that for 20- and 60-nm-thick Al thin films. Morphological changes leading to the crystallization of the Al2O3 thin films were also observed when the thickness of Al thin films increased from 10 to 20 and 60 nm.

  18. Aqueous phase deposition of dense tin oxide films with nano-structured surfaces

    SciTech Connect

    Masuda, Yoshitake Ohji, Tatsuki; Kato, Kazumi

    2014-06-01

    Dense tin oxide films were successfully fabricated in an aqueous solution. The pH of the solutions was controlled to pH 1.3 by addition of HCl. Precise control of solution condition and crystal growth allowed us to obtain dense tin oxide films. Concave–convex surface of fluorine-doped tin oxide (FTO) substrates was entirely-covered with the continuous films. The films were about 65 nm in thickness and had nano-structured surfaces. Morphology of the films was strikingly different from our previous reported nano-sheet assembled structures. The films were not removed from the substrates by strong water flow or air blow to show strong adhesion strength. The aqueous solution process can be applied to surface coating of various materials such as nano/micro-structured surfaces, particles, fibers, polymers, metals or biomaterials. - Graphical abstract: Dense tin oxide films of 65 nm were successfully fabricated in an aqueous solution. They had nano-structured surfaces. Concave-convex substrates were entirely-covered with the continuous films. - Highlights: • Dense tin oxide films of 65 nm were successfully fabricated in an aqueous solution. • They had nano-structured surfaces. • Concave–convex substrates were entirely-covered with the continuous films.

  19. Kinetics and mechanism of high-temperature oxidation of copper covered by bismuth thin films

    SciTech Connect

    Belousov, V.V. )

    1992-10-01

    The oxidation kinetics of copper covered by thin films of bismuth were studied by TGA, X-ray diffraction, X-ray micro-elemental, coulombmetric methods, and by electron and optional microscopy. At 1,003 K catastrophic oxidation of copper coated by bismuth thin films was observed. The parabolic rate constant of copper oxidation (Kp) depends markedly on the thickness of the bismuth film and is more than 1,000 times greater than that of bare copper. The mechanism of catastrophic copper oxidation in contact with bismuth is discussed.

  20. Study of zinc oxide epitaxial film growth and UV photodetectors

    NASA Astrophysics Data System (ADS)

    Nahhas, Ahmed Mohammed

    ZnO is a versatile material, and has been extensively studied for various applications such as varistors, transducers, transparent conducting electrodes, sensors, and catalysts. While polycrystalline ZnO is commonly used in these conventional applications, there has been a growing interest in obtaining single-crystalline ZnO films on various substrates. ZnO is a II-VI wide bandgap semiconductor with a relatively large exciton binding energy, and holds a potential for light emitting/detecting or nonlinear optical devices in the UV range. ZnO is isomorphic to wurtzite GaN with good lattice match, and therefore there has been a great deal of interest in using ZnO as a buffer layer or a substrate in growing high quality GaN films (or vice versa ZnO growth on GaN). In this study, we have investigated epitaxial growth of ZnO films on sapphire and silicon substrates. High quality epitaxial ZnO films were grown on sapphire (0001) single crystal substrates using a rf magnetron sputtering technique. X-ray diffraction analysis shows that the ZnO films are of a monocrystalline wurtzite structure with their epitaxial relationship of ZnO[0001]//sapphire[0001] along the growth direction and ZnO[112&barbelow;0]//sapphire[11&barbelow;00] along the in-plane direction. ZnO on Si also offers an interesting opportunity that the various functional properties of ZnO can be combined with the advanced Si electronics on the same substrate. Direct growth of epitaxial ZnO on Si, however, is known to be an extremely difficult task due to the oxidation problem during the nucleation stage of a ZnO growth process. We have overcome this problem by introducing an epitaxial GaN buffer layer, and have successfully grown epitaxial ZnO films on Si(111) substrates. X-ray diffraction analysis confirms an epitaxial relationship of ZnO[0001]//GaN[0001]//Si[111] along the growth direction and ZnO[112&barbelow;0]//GaN[112&barbelow;0]//Si[11&barbelow;0] along the in-plane direction. As an application of the

  1. On the Design of Oxide Films, Nanomaterials, and Heterostructures for Solar Water Oxidation Photoanodes

    NASA Astrophysics Data System (ADS)

    Kronawitter, Coleman Xaver

    Photoelectrochemistry and its associated technologies show unique potential to facilitate the large-scale production of solar fuels—those energy-rich chemicals obtained through conversion processes driven by solar energy, mimicking the photosynthetic process of green plants. The critical component of photoelectrochemical devices designed for this purpose is the semiconductor photoelectrode, which must be optically absorptive, chemically stable, and possess the required electronic band alignment with respect to the redox couple of the electrolyte to drive the relevant electrochemical reactions. After many decades of investigation, the primary technological obstacle remains the development of photoelectrode structures capable of efficient and stable conversion of light with visible frequencies, which is abundant in the solar spectrum. Metal oxides represent one of the few material classes that can be made photoactive and remain stable to perform the required functions. The unique range of functional properties of oxides, and especially the oxides of transition metals, relates to their associated diversity of cation oxidation states, cation electronic configurations, and crystal structures. In this dissertation, the use of metal oxide films, nanomaterials, and heterostructures in photoelectrodes enabling the solar-driven oxidation of water and generation of hydrogen fuel is examined. A range of transition- and post-transition-metal oxide material systems and nanoscale architectures is presented. The first chapters present results related to electrodes based on alpha-phase iron(III) oxide, a promising visible-light-active material widely investigated for this application. Studies of porous films fabricated by physical vapor deposition reveal the importance of structural quality, as determined by the deposition substrate temperature, on photoelectrochemical performance. Heterostructures with nanoscale feature dimensionality are explored and reviewed in a later chapter

  2. Metal oxide semiconductor thin-film transistors for flexible electronics

    SciTech Connect

    Petti, Luisa; Vogt, Christian; Büthe, Lars; Cantarella, Giuseppe; Tröster, Gerhard; Münzenrieder, Niko; Faber, Hendrik; Bottacchi, Francesca; Anthopoulos, Thomas D.

    2016-06-15

    The field of flexible electronics has rapidly expanded over the last decades, pioneering novel applications, such as wearable and textile integrated devices, seamless and embedded patch-like systems, soft electronic skins, as well as imperceptible and transient implants. The possibility to revolutionize our daily life with such disruptive appliances has fueled the quest for electronic devices which yield good electrical and mechanical performance and are at the same time light-weight, transparent, conformable, stretchable, and even biodegradable. Flexible metal oxide semiconductor thin-film transistors (TFTs) can fulfill all these requirements and are therefore considered the most promising technology for tomorrow's electronics. This review reflects the establishment of flexible metal oxide semiconductor TFTs, from the development of single devices, large-area circuits, up to entirely integrated systems. First, an introduction on metal oxide semiconductor TFTs is given, where the history of the field is revisited, the TFT configurations and operating principles are presented, and the main issues and technological challenges faced in the area are analyzed. Then, the recent advances achieved for flexible n-type metal oxide semiconductor TFTs manufactured by physical vapor deposition methods and solution-processing techniques are summarized. In particular, the ability of flexible metal oxide semiconductor TFTs to combine low temperature fabrication, high carrier mobility, large frequency operation, extreme mechanical bendability, together with transparency, conformability, stretchability, and water dissolubility is shown. Afterward, a detailed analysis of the most promising metal oxide semiconducting materials developed to realize the state-of-the-art flexible p-type TFTs is given. Next, the recent progresses obtained for flexible metal oxide semiconductor-based electronic circuits, realized with both unipolar and complementary technology, are reported. In particular

  3. Metal oxide semiconductor thin-film transistors for flexible electronics

    NASA Astrophysics Data System (ADS)

    Petti, Luisa; Münzenrieder, Niko; Vogt, Christian; Faber, Hendrik; Büthe, Lars; Cantarella, Giuseppe; Bottacchi, Francesca; Anthopoulos, Thomas D.; Tröster, Gerhard

    2016-06-01

    The field of flexible electronics has rapidly expanded over the last decades, pioneering novel applications, such as wearable and textile integrated devices, seamless and embedded patch-like systems, soft electronic skins, as well as imperceptible and transient implants. The possibility to revolutionize our daily life with such disruptive appliances has fueled the quest for electronic devices which yield good electrical and mechanical performance and are at the same time light-weight, transparent, conformable, stretchable, and even biodegradable. Flexible metal oxide semiconductor thin-film transistors (TFTs) can fulfill all these requirements and are therefore considered the most promising technology for tomorrow's electronics. This review reflects the establishment of flexible metal oxide semiconductor TFTs, from the development of single devices, large-area circuits, up to entirely integrated systems. First, an introduction on metal oxide semiconductor TFTs is given, where the history of the field is revisited, the TFT configurations and operating principles are presented, and the main issues and technological challenges faced in the area are analyzed. Then, the recent advances achieved for flexible n-type metal oxide semiconductor TFTs manufactured by physical vapor deposition methods and solution-processing techniques are summarized. In particular, the ability of flexible metal oxide semiconductor TFTs to combine low temperature fabrication, high carrier mobility, large frequency operation, extreme mechanical bendability, together with transparency, conformability, stretchability, and water dissolubility is shown. Afterward, a detailed analysis of the most promising metal oxide semiconducting materials developed to realize the state-of-the-art flexible p-type TFTs is given. Next, the recent progresses obtained for flexible metal oxide semiconductor-based electronic circuits, realized with both unipolar and complementary technology, are reported. In particular

  4. Graphene-based thin film supercapacitor with graphene oxide as dielectric spacer

    NASA Astrophysics Data System (ADS)

    Liu, Jinzhang; Galpaya, Dilini; Notarianni, Marco; Yan, Cheng; Motta, Nunzio

    2013-08-01

    Thin film supercapacitors are produced by using electrochemically exfoliated graphene (G) and wet-chemically produced graphene oxide (GO). Either G/GO/G stacked film or sole GO film are sandwiched by two Au films to make devices, where GO is the dielectric spacer. The addition of graphene film can increase the capacitance about two times, compared to the simple Au electrode. It is found that the GO film has very high dielectric constant, accounting for the high capacitance. AC measurement reveals that the relative permittivity of GO is in the order of 104 within the frequency range of 0.1-70 Hz.

  5. Growth and characterization of single phase Cu2O by thermal oxidation of thin copper films

    NASA Astrophysics Data System (ADS)

    Choudhary, Sumita; Sarma, J. V. N.; Gangopadhyay, Subhashis

    2016-04-01

    We report a simple and efficient technique to form high quality single phase cuprous oxide films on glass substrate using thermal evaporation of thin copper films followed by controlled thermal oxidation in air ambient. Crystallographic analysis and oxide phase determination, as well as grain size distribution have been studied using X-ray diffraction (XRD) method, while scanning electron microscopy (SEM) has been utilized to investigate the surface morphology of the as grown oxide films. The formation of various copper oxide phases is found to be highly sensitive to the oxidation temperature and a crystalline, single phase cuprous oxide film can be achieved for oxidation temperatures between 250°C to 320°C. Cu2O film surface appeared in a faceted morphology in SEM imaging and a direct band gap of about 2.1 eV has been observed in UV-visible spectroscopy. X-ray photoelectron spectroscopy (XPS) confirmed a single oxide phase formation. Finally, a growth mechanism of the oxide film has also been discussed.

  6. Investigation of the gate oxide leakage current of low temperature formed hafnium oxide films

    NASA Astrophysics Data System (ADS)

    Verrelli, E.; Tsoukalas, D.

    2013-03-01

    In this work, low temperature physically deposited hafnium oxide films are investigated in terms of their electrical properties through measurements and analysis of leakage currents in order to understand the defect's behavior in this dielectric material. Two extreme conditions will be presented and discussed: the first one concerns the use of a nearly trap-free hafnium oxide layer, while the second one concerns the use of a hafnium oxide film with a very large amount of electrically active traps. Particular emphasis is given to the detection and comparison of the shallow and deep traps that are responsible for the room temperature leakage of these films. It is shown that by modifying the amount of traps in the hafnium oxide layer, achieved by changing the deposition conditions, the trap's energy location is heavily influenced. The nearly trap-free sample exhibits Ohmic conduction at low fields (with activation energies in the range 16-33 meV for low temperatures and 0.13-0.14 eV for higher than ambient temperatures), Poole-Frenkel conduction at high fields (trap depth in the range 0.23-0.38 eV), while at low temperatures and high fields, the Fowler-Nordheim tunneling is identified (estimated barrier height of 1.9 eV). The charge-trap sample on the other hand exhibits Ohmic conduction at low fields (activation energies in the range 0.26-0.32 eV for higher than ambient temperatures), space charge limited current conduction at intermediate fields (exponent n = 3), while at high fields the Poole-Frenkel conduction appears (trap depth in the range 1.63-1.70 eV).

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

    NASA Astrophysics Data System (ADS)

    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

  8. Fabrication and characterization of oxide-based thin film transistors, and process development for oxide heterostructures

    NASA Astrophysics Data System (ADS)

    Lim, Wantae

    2009-12-01

    This dissertation is focused on the development of thin film transistors (TFTs) using oxide materials composed of post-transitional cations with (n-1)d 10ns0 (n≥4). The goal is to achieve high performance oxide-based TFTs fabricated at low processing temperature on either glass or flexible substrates for next generation display applications. In addition, etching mechanism and Ohmic contact formation for oxide heterostructure (ZnO/CuCrO 2) system is demonstrated. The deposition and characterization of oxide semiconductors (In 2O3-ZnO, and InGaZnO4) using a RF-magnetron sputtering system are studied. The main influence on the resistivity of the films is found to be the oxygen partial pressure in the sputtering ambient. The films remained amorphous and transparent (> 70%) at all process conditions. These films showed good transmittance at suitable conductivity for transistor fabrication. The electrical characteristics of both top- and bottom-gate type Indium Zinc Oxide (InZnO) and Indium Gallium Zinc Oxide (InGaZnO4)-based TFTs are reported. The InZnO films were favorable for depletion-mode TFTs due to their tendency to form oxygen vacancies, while enhancement-mode devices were realized with InGaZnO4 films. The InGaZnO4-based TFTs fabricated on either glass or plastic substrates at low temperature (<100°C) exhibit good electrical properties: the saturation mobility of 5--12 cm2.V-1.s-1 and threshold voltage of 0.5--2.5V. The devices are also examined as a function of aging time in order to verify long-term stability in air. The effect of gate dielectric materials on electrical properties of InGaZnO 4-based TFTs was investigated. The use of SiNx film as a gate dielectric reduces the trap density and the roughness at the channel/gate dielectric interface compared to SiO2 gate dielectric, resulting in an improvement of device parameters by reducing scattering of trapped charges at the interface. The quality of interface is shown to have large effect on TFT performance

  9. Metal oxide films with magnetically modulated nanoporous architectures

    NASA Astrophysics Data System (ADS)

    Grimes, Craig A.; Singh, R. S.; Dickey, Elizabeth; Varghese, Oomman

    2001-12-01

    A magnetically-driven method for controlling nano- dimensional porosity in sol gel derived metal oxide films, including TiO2, Al2O3, and SnO2, coated onto ferromagnetic amorphous substrates, such as the magnetically-soft Metglas alloys, is described. Based on the porous structures observed dependence on external magnetic field, a model is suggested to explain the phenomena. Under well-defined conditions it appears that the sol particles coming out of solution, and undergoing Brownian motion, follow the magnetic field lines oriented perpendicularly to the substrate surface associated with the magnetic domain walls of the substrate; hence the porosity developed during solvent evaporation correlates with the magnetic domain size.

  10. Continuously controlled optical band gap in oxide semiconductor thin films

    DOE PAGES

    Herklotz, Andreas; Rus, Stefania Florina; Ward, Thomas Zac

    2016-02-02

    The optical band gap of the prototypical semiconducting oxide SnO2 is shown to be continuously controlled through single axis lattice expansion of nanometric films induced by low-energy helium implantation. While traditional epitaxy-induced strain results in Poisson driven multidirectional lattice changes shown to only allow discrete increases in bandgap, we find that a downward shift in the band gap can be linearly dictated as a function of out-of-plane lattice expansion. Our experimental observations closely match density functional theory that demonstrates that uniaxial strain provides a fundamentally different effect on the band structure than traditional epitaxy-induced multiaxes strain effects. In conclusion, chargemore » density calculations further support these findings and provide evidence that uniaxial strain can be used to drive orbital hybridization inaccessible with traditional strain engineering techniques.« less

  11. Continuously controlled optical band gap in oxide semiconductor thin films

    SciTech Connect

    Herklotz, Andreas; Rus, Stefania Florina; Ward, Thomas Zac

    2016-02-02

    The optical band gap of the prototypical semiconducting oxide SnO2 is shown to be continuously controlled through single axis lattice expansion of nanometric films induced by low-energy helium implantation. While traditional epitaxy-induced strain results in Poisson driven multidirectional lattice changes shown to only allow discrete increases in bandgap, we find that a downward shift in the band gap can be linearly dictated as a function of out-of-plane lattice expansion. Our experimental observations closely match density functional theory that demonstrates that uniaxial strain provides a fundamentally different effect on the band structure than traditional epitaxy-induced multiaxes strain effects. In conclusion, charge density calculations further support these findings and provide evidence that uniaxial strain can be used to drive orbital hybridization inaccessible with traditional strain engineering techniques.

  12. Electrophoretic deposition of PTFE particles on porous anodic aluminum oxide film and its tribological properties

    NASA Astrophysics Data System (ADS)

    Zhang, Dongya; Dong, Guangneng; Chen, Yinjuan; Zeng, Qunfeng

    2014-01-01

    Polytetrafluoroethylene (PTFE) composite film was successfully fabricated by depositing PTFE particles into porous anodic aluminum oxide film using electrophoretic deposition (EPD) process. Firstly, porous anodic aluminum oxide film was synthesized by anodic oxidation process in sulphuric acid electrolyte. Then, PTFE particles in suspension were directionally deposited into the porous substrate. Finally, a heat treatment at 300 °C for 1 h was utilized to enhance PTFE particles adhesion to the substrate. The influence of anodic oxidation parameters on the morphology and micro-hardness of the porous anodic aluminum oxide film was studied and the PTFE particles deposited into the pores were authenticated using energy-dispersive spectrometer (EDS) and scanning electron microscopy (SEM). Tribological properties of the PTFE composite film were investigated under dry sliding. The experimental results showed that the composite film exhibit remarkable low friction. The composite film had friction coefficient of 0.20 which deposited in 15% PTFE emulsion at temperature of 15 °C and current density of 3 A/dm2 for 35 min. In addition, a control specimen of porous anodic aluminum oxide film and the PTFE composite film were carried out under the same test condition, friction coefficient of the PTFE composite film was reduced by 60% comparing with the control specimen at 380 MPa and 100 mm/s. The lubricating mechanism was that PTFE particles embedded in porous anodic aluminum oxide film smeared a transfer film on the sliding path and the micro-pores could support the supplement of solid lubricant during the sliding, which prolonged the lubrication life of the aluminum alloys.

  13. Decomposition of Organometal Halide Perovskite Films on Zinc Oxide Nanoparticles.

    PubMed

    Cheng, Yuanhang; Yang, Qing-Dan; Xiao, Jingyang; Xue, Qifan; Li, Ho-Wa; Guan, Zhiqiang; Yip, Hin-Lap; Tsang, Sai-Wing

    2015-09-16

    Solution processed zinc oxide (ZnO) nanoparticles (NPs) with excellent electron transport properties and a low-temperature process is a viable candidate to replace titanium dioxide (TiO2) as electron transport layer to develop high-efficiency perovskite solar cells on flexible substrates. However, the number of reported high-performance perovskite solar cells using ZnO-NPs is still limited. Here we report a detailed investigation on the chemistry and crystal growth of CH3NH3PbI3 perovskite on ZnO-NP thin films. We find that the perovskite films would severely decompose into PbI2 upon thermal annealing on the bare ZnO-NP surface. X-ray photoelectron spectroscopy (XPS) results show that the hydroxide groups on the ZnO-NP surface accelerate the decomposition of the perovskite films. To reduce the decomposition, we introduce a buffer layer in between the ZnO-NPs and perovskite layers. We find that a commonly used buffer layer with small molecule [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) can slow down but cannot completely avoid the decomposition. On the other hand, a polymeric buffer layer using poly(ethylenimine) (PEI) can effectively separate the ZnO-NPs and perovskite, which allows larger crystal formation with thermal annealing. The power conversion efficiencies of perovskite photovoltaic cells are significantly increased from 6.4% to 10.2% by replacing PC61BM with PEI as the buffer layer.

  14. Chemical Strain Engineering of Magnetism in Oxide Thin Films.

    PubMed

    Copie, Olivier; Varignon, Julien; Rotella, Hélène; Steciuk, Gwladys; Boullay, Philippe; Pautrat, Alain; David, Adrian; Mercey, Bernard; Ghosez, Philippe; Prellier, Wilfrid

    2017-04-03

    Transition metal oxides having a perovskite structure form a wide and technologically important class of compounds. In these systems, ferroelectric, ferromagnetic, ferroelastic, or even orbital and charge orderings can develop and eventually coexist. These orderings can be tuned by external electric, magnetic, or stress field, and the cross-couplings between them enable important multifunctional properties, such as piezoelectricity, magneto-electricity, or magneto-elasticity. Recently, it has been proposed that additional to typical fields, the chemical potential that controls the concentration of ion vacancies in these systems may reveal an efficient alternative parameter to further tune their properties and achieve new functionalities. In this study, concretizing this proposal, the authors show that the control of the content of oxygen vacancies in perovskite thin films can indeed be used to tune their magnetic properties. Growing PrVO3 thin films epitaxially on an SrTiO3 substrate, the authors reveal a concrete pathway to achieve this effect. The authors demonstrate that monitoring the concentration of oxygen vacancies through the oxygen partial pressure or the growth temperature can produce a substantial macroscopic tensile strain of a few percent. In turn, this strain affects the exchange interactions, producing a nontrivial evolution of Néel temperature in a range of 30 K.

  15. XPS depth profiling study on the passive oxide film of carbon steel in saturated calcium hydroxide solution and the effect of chloride on the film properties

    NASA Astrophysics Data System (ADS)

    Ghods, P.; Isgor, O. B.; Brown, J. R.; Bensebaa, F.; Kingston, D.

    2011-03-01

    X-ray photoelectron spectroscopy (XPS) was used to study the properties of passive oxide film that form on carbon steel in saturated calcium hydroxide solution and the effect of chloride on the film properties. The thickness of the oxide films was determined to be approximately 4 nm and was not affected by the exposure time. Near the film/substrate interface the concentration of the Fe2+ oxides was higher than the concentration of the Fe3+ oxides; the layers near the free surface of the film mostly contained Fe3+ oxides. Chloride exposure decreased the thickness of the oxide films and changed their stoichiometry such that near the film/substrate interface Fe3+/Fe2+ ratio increased.

  16. High Transparent Conductive Aluminum-Doped Zinc Oxide Thin Films by Reactive Co-Sputtering (Postprint)

    DTIC Science & Technology

    2016-03-30

    AFRL-RX-WP-JA-2017-0144 HIGH TRANSPARENT CONDUCTIVE ALUMINUM - DOPED ZINC OXIDE THIN FILMS BY REACTIVE CO- SPUTTERING (POSTPRINT...TRANSPARENT CONDUCTIVE ALUMINUM -DOPED ZINC OXIDE THIN FILMS BY REACTIVE CO-SPUTTERING (POSTPRINT) 5a. CONTRACT NUMBER FA8650-16-D-5402-0001 5b. GRANT...ANSI Std. Z39-18 TD.11.pdf Optical Interference Coatings (OIC) 2016 © OSA 2016 1 High Transparent Conductive Aluminum -doped Zinc Oxide Thin

  17. High dielectric constant nickel-doped titanium oxide films prepared by liquid-phase deposition

    NASA Astrophysics Data System (ADS)

    Lee, Ming-Kwei; Yen, Chih-Feng; Fan, Cho-Han

    2014-09-01

    The electrical characteristics of nickel-doped titanium oxide films prepared by liquid-phase deposition on p-type (100) silicon substrate were investigated. The aqueous solutions of ammonium hexafluorotitanate and boric acid were used as precursors for the growth of titanium oxide films and the dielectric constant is 29. The dielectric constant can be improved to 94 by nickel doping at the thermal annealing at 700 °C in nitrous oxide.

  18. p-Channel oxide thin film transistors using solution-processed copper oxide.

    PubMed

    Kim, Sang Yun; Ahn, Cheol Hyoun; Lee, Ju Ho; Kwon, Yong Hun; Hwang, Sooyeon; Lee, Jeong Yong; Cho, Hyung Koun

    2013-04-10

    Cu2O thin films were synthesized on Si (100) substrate with thermally grown 200-nm SiO2 by sol-gel spin coating method and postannealing under different oxygen partial pressure (0.04, 0.2, and 0.9 Torr). The morphology of Cu2O thin films was improved through N2 postannealing before O2 annealing. Under relatively high oxygen partial pressure of 0.9 Torr, the roughness of synthesized films was increased with the formation of CuO phase. Bottom-gated copper oxide (CuxO) thin film transistors (TFTs) were fabricated via conventional photolithography, and the electrical properties of the fabricated TFTs were measured. The resulting Cu2O TFTs exhibited p-channel operation, and field effect mobility of 0.16 cm2/(V s) and on-to-off drain current ratio of ∼1×10(2) were observed in the TFT device annealed at PO2 of 0.04 Torr. This study presented the potential of the solution-based process of the Cu2O TFT with p-channel characteristics for the first time.

  19. Nickel oxide and molybdenum oxide thin films for infrared imaging prepared by biased target ion-beam deposition

    NASA Astrophysics Data System (ADS)

    Jin, Yao; Saint John, David; Jackson, Tom N.; Horn, Mark W.

    2014-06-01

    Vanadium oxide (VOx) thin films have been intensively used as sensing materials for microbolometers. VOx thin films have good bolometric properties such as low resistivity, high negative temperature coefficient of resistivity (TCR) and low 1/f noise. However, the processing controllability of VOx fabrication is difficult due to the multiple valence states of vanadium. In this study, metal oxides such as nickel oxide (NiOx) and molybdenum oxide (MoOx) thin films have been investigated as possible new microbolometer sensing materials with improved process controllability. Nickel oxide and molybdenum oxide thin films were prepared by reactive sputtering of nickel and molybdenum metal targets in a biased target ion beam deposition tool. In this deposition system, the Ar+ ion energy (typically lower than 25 eV) and the target bias voltage can be independently controlled since ions are remotely generated. A residual gas analyzer (RGA) is used to precisely control the oxygen partial pressure. A real-time spectroscopic ellipsometry is used to monitor the evolution of microstructure and properties of deposited oxides during growth and post-deposition. The properties of deposited oxide thin films depend on processing parameters. The resistivity of the NiOx thin films is in the range of 0.5 to approximately 100 ohm-cm with a TCR from -2%/K to -3.3%/K, where the resistivity of MoOx is between 3 and 2000 ohm-cm with TCR from -2.1%/K to -3.2%/K. We also report on the thermal stability of these deposited oxide thin films.

  20. Zinc Oxide Thin Films Fabricated with Direct Current Magnetron Sputtering Deposition Technique

    SciTech Connect

    Hoon, Jian-Wei; Chan, Kah-Yoong; Krishnasamy, Jegenathan; Tou, Teck-Yong

    2011-03-30

    Zinc oxide (ZnO) is a very promising material for emerging large area electronic applications including thin-film sensors, transistors and solar cells. We fabricated ZnO thin films by employing direct current (DC) magnetron sputtering deposition technique. ZnO films with different thicknesses ranging from 100 nm to 1020 nm were deposited on silicon (Si) substrate. The deposition pressure was varied from 12 mTorr to 25 mTorr. The influences of the film thickness and the deposition pressure on structural properties of the ZnO films were investigated using Mahr surface profilometer and atomic force microscopy (AFM). The experimental results reveal that the film thickness and the deposition pressure play significant role in the structural formation of the deposited ZnO thin films. ZnO films deposited on Si substrates are promising for variety of thin-film sensor applications.

  1. Interfacial development of electrophoretically deposited graphene oxide films on Al alloys

    DOE PAGES

    Jin, Sumin; Dickerson, James H.; Pham, Viet Hung; ...

    2015-07-28

    Adhesion between film and substrate is critical for electronic device and coating applications. Interfacial development between electrophoretically deposited graphene oxide films on Al 1100 and Al 5052 alloys were investigated using FT-IR and XPS depth profiling techniques. Obtained results suggest metal ion permeation from the substrates into deposited graphene oxide films. The interface between the films and the substrates were primarily composed of Al-O-C bonds from oxygenated defects on graphene oxide plane rather than expected Al-C formation. Films heat treated at 150 °C had change in microstructure and peak shifts in XPS spectra suggesting change in chemical structure of bondsmore » between the films and the substrates.« less

  2. Interfacial development of electrophoretically deposited graphene oxide films on Al alloys

    SciTech Connect

    Jin, Sumin; Dickerson, James H.; Pham, Viet Hung; Brochu, Mathieu

    2015-07-28

    Adhesion between film and substrate is critical for electronic device and coating applications. Interfacial development between electrophoretically deposited graphene oxide films on Al 1100 and Al 5052 alloys were investigated using FT-IR and XPS depth profiling techniques. Obtained results suggest metal ion permeation from the substrates into deposited graphene oxide films. The interface between the films and the substrates were primarily composed of Al-O-C bonds from oxygenated defects on graphene oxide plane rather than expected Al-C formation. Films heat treated at 150 °C had change in microstructure and peak shifts in XPS spectra suggesting change in chemical structure of bonds between the films and the substrates.

  3. Impact of acid and oxidative modifications, single or dual, of sorghum starch on biodegradable films.

    PubMed

    Biduski, Bárbara; Silva, Francine Tavares da; Silva, Wyller Max da; Halal, Shanise Lisie de Mello El; Pinto, Vania Zanella; Dias, Alvaro Renato Guerra; Zavareze, Elessandra da Rosa

    2017-01-01

    The objective of this study was to evaluate the effects of acid and oxidation modifications on sorghum starch, as well as the effect of dual modification of starch on the physical, morphological, mechanical, and barrier properties of biodegradable films. The acid modification was performed with 3% lactic acid and the oxidation was performed with 1.5% active chlorine. For dual modification, the acid modification was performed first, followed by oxidation under the same conditions as above. Both films of the oxidized starches, single and dual, had increased stiffness, providing a higher tensile strength and lower elongation when compared to films based on native and single acid modified starches. However, the dual modification increased the water vapor permeability of the films without changing their solubility. The increase in sorghum starch concentration in the filmogenic solution increased the thickness, water vapor permeability, and elongation of the films. Copyright © 2016. Published by Elsevier Ltd.

  4. Mechanical properties of bioplastics cassava starch film with Zinc Oxide nanofiller as reinforcement

    NASA Astrophysics Data System (ADS)

    Harunsyah; Yunus, M.; Fauzan, Reza

    2017-06-01

    This study focuses on investigating the influence of zinc oxide nanofiller on the mechanical properties of bioplastic cassava starch films. Bioplastic cassava starch film-based zinc oxide reinforced composite biopolymeric films were prepared by casting technique. The content of zinc oxide in the bioplastic films was varied from 0.2%, 0.4%, 0.6%, 0.8% and 1.0% (w/w) by weight of starch. Surface morphologies of the composites bioplastic films were examined by scanning electron microscope (SEM).The result showed that the Tensile strength (TS) was improved significantly with the additional of zinc oxide but the elongation at break (EB %) of the composites was decreased. The maximum tensile strength obtained was 22.30 kgf / mm on the additional of zinc oxide by 0.6% and plastilizer by 25%. Based on data of FTIR, the produced film plastic did not change the group function and it can be concluded that theinteraction in film plastic produced was only a physical interaction. Biodegradable plastic film based on cassava starch-zinc oxide and plasticizer glycerol showed that interesting mechanical properties being transparent, clear, homogeneous, flexible, and easily handled.

  5. Copper Oxide Substrates and Epitaxial Copper Oxide/Zinc Oxide Thin Film Heterostructures for Solar Energy Conversion

    NASA Astrophysics Data System (ADS)

    Darvish, Davis Solomon

    Future fossil fuel scarcity and environmental degradation have demonstrated the need for renewable, low-carbon sources of energy to power an increasingly industrialized world. Solar energy with its infinite supply makes it an extraordinary resource that should not go unused. However with current materials, adoption is limited by cost and so a paradigm shift must occur to get everyone on the same page embracing solar technology. Cuprous Oxide (Cu2O) is a promising earth abundant material that can be a great alternative to traditional thin-film photovoltaic materials like CIGS, CdTe, etc. We have prepared Cu 2O bulk substrates by the thermal oxidation of copper foils as well Cu2O thin films deposited via plasma-assisted Molecular Beam Epitaxy. From preliminary Hall measurements it was determined that Cu2O would need to be doped extrinsically. This was further confirmed by simulations of ZnO/Cu2O heterojunctions. A cyclic interdependence between, defect concentration, minority carrier lifetime, film thickness, and carrier concentration manifests itself a primary reason for why efficiencies greater than 4% has yet to be realized. Our growth methodology for our thin-film heterostructures allow precise control of the number of defects that incorporate into our film during both equilibrium and nonequilibrium growth. We also report process flow/device design/fabrication techniques in order to create a device. A typical device without any optimizations exhibited open-circuit voltages Voc, values in excess 500mV; nearly 18% greater than previous solid state devices.

  6. Ultraviolet-reduced reduction and crystallization of indium oxide films

    NASA Astrophysics Data System (ADS)

    Imai, Hiroaki; Tominaga, Atsushi; Hirashima, Hiroshi; Toki, Motoyuki; Asakuma, Naoko

    1999-01-01

    Structural changes stimulated by ultraviolet (UV) irradiations of sol-gel-derived indium oxide thin films were investigated. Illumination of incoherent UV photons (4.9 eV) from a low-pressure mercury lamp resulted in formation of crystalline indium metal. Irradiation of coherent UV beams from an ArF excimer laser (6.4 eV) and from the fourth harmonics of a Nd:YAG laser (4.7 eV) was found to be effective in the crystallization of indium oxide, accompanied by a decrease in the sheet resistance. The lowest resistance without a reduction of transmission in the visible region was achieved with a 6.4 eV laser beam at a fluence over 10-20 mJ cm-2 shot-1. The results of x-ray photoelectron spectroscopy revealed that charge transfer from O2- to In3+ was induced by the incoherent and the coherent UV photons. The partial reduction with the incoherent illumination and the crystallization with the laser irradiation are tentatively assumed to be due to electronic excitations in the amorphous network.

  7. Functional Multilayered Transparent Conducting Oxide Thin Films for Photovoltaic Devices

    SciTech Connect

    Noh, J. H.; Lee, S.; Kim, J. Y.; Lee, J. K.; Han, H. S.; Cho, C. M.; Cho, I. S.; Jung, H. S.; Hong, K. S.

    2009-01-01

    In this study, we present a thermally stable multilayered transparent conducting oxide (TCO) functionalized for dye-sensitized solar cells (DSSCs). Nb-doped TiO{sub 2} (NTO) layers deposited on conventional Sn-doped In{sub 2}O{sub 3} (ITO) substrates using pulsed laser deposition (PLD) enhanced the optical-to-electrical conversion efficiency of the DSSCs by as much as 17% compared to that of bare ITO-based DSSCs. The electrical properties and J-V characteristics of the multilayered NTO/ITO films showed that the improved cell performance was due to the facilitated charge injection from TiO{sub 2} to ITO that resulted from the formation of an ohmic contact with ITO, as well as the conserved high conductivity of ITO after the oxidizing annealing process. Moreover, the NTO/ITO-based DSSC exhibited higher efficiency than a F-doped SnO{sub 2}(FTO)-based one, which demonstrates that optimization of multilayered NTO-based TCOs is a realistic approach for achieving highly efficient photoenergy conversion devices.

  8. Absorption of ac fields in amorphous indium-oxide films

    SciTech Connect

    Ovadyahu, Z.

    2014-08-20

    Absorption data from applied ac fields in Anderson-localized amorphous indium-oxide (In{sub x}O) films are shown to be frequency and disorder dependent. The absorption shows a roll-off at a frequency which is much lower than the electron-electron scattering rate of the material when it is in the diffusive regime. This is interpreted as evidence for discreteness of the energy spectrum of the deeply localized regime. This is consistent with recent many-body localization scenarios. As the metal-insulator transition is approached, the absorption shifts to higher frequencies. Comparing with the previously obtained results on the crystalline version of indium-oxide (In{sub 2}O{sub 3−x}) implies a considerably higher inelastic electron-phonon scattering rate in the amorphous material. The range over which the absorption versus frequency decreases may indicate that a wide distribution of localization length is a common feature in these systems.

  9. Production of Silicon Oxide like Thin Films by the Use of Atmospheric Plasma Torch

    NASA Astrophysics Data System (ADS)

    Ozono, E. M.; Fachini, E. R.; Silva, M. L. P.; Ruchko, L. F.; Galvão, R. M. O.

    2015-03-01

    The advantages of HMDS (hexamethyldisilazane) APT-plasma films for sensor applications were explored producing films in a three-turn copper coil APT equipment. HMDS was introduced into the argon plasma at four different conditions. Additional flux of oxygen could modulate the presence of organic components in the film, the composition varying from pure inorganic oxides to organo-silane polymers. Oxygen promoted deposition rates as high as 900 nm/min on silicon, acrylic or piezoelectric quartz crystal substrates. Films with a clustered morphology and refractive index of 1.45 were obtained, mainly due to a silicon oxide structure. Raman spectroscopy and XPS data showed the presence of CHn and amorphous carbon in the inorganic matrix. The films were sensitive to the humidity of the air. The adsorptive capabilities of outstanding films were tested in a Quartz Crystal Microbalance (QCM). The results support that those films can be a useful and simple alternative for the development of sensors.

  10. The role of polymer films on the oxidation of magnetite nanoparticles

    NASA Astrophysics Data System (ADS)

    Letti, C. J.; Paterno, L. G.; Pereira-da-Silva, M. A.; Morais, P. C.; Soler, M. A. G.

    2017-02-01

    A detailed investigation about the role of polymer films on the oxidation process of magnetite nanoparticles (∼7 nm diameter), under laser irradiation is performed employing micro Raman spectroscopy. To support this investigation, Fe3O4-np are synthesized by the co-precipitation method and assembled layer-by-layer with sodium sulfonated polystyrene (PSS). Polymer films (Fe3O4-np/PSS)n with n=2,3,5,7,10 and 25 bilayers are employed as a model system to study the oxidation process under laser irradiation. Raman data are further processed by principal component analysis. Our findings suggest that PSS protects Fe3O4-np from oxidation when compared to powder samples, even for the sample with the greater number of bilayers. Further, the oxidation of magnetite to maghemite occurs preferably for thinner films up to 7 bilayers, while the onset for the formation of the hematite phase depends on the laser intensity for thicker films. Water takes part on the oxidation processes of magnetite, the oxidation/phase transformation of Fe3O4-np is intensified in films with more bilayers, since more water is included in those films. Encapsulation of Fe3O4-np by PSS in layer-by-layer films showed to be very efficient to avoid the oxidation process in nanosized magnetite.

  11. Thin film synthesis of novel electrode materials for solid-oxide fuel cells

    SciTech Connect

    Jankowski, A.F.; Morse, J.D.

    1997-12-01

    Electrode materials for solid-oxide fuel cells are developed using sputter deposition. A thin film anode is formed by co-deposition of nickel and yttria-stabilized zirconia. This approach is suitable for composition grading and the provision of a mixed-conducting interracial layer to the electrolyte layer. Similarly, synthesis of a thin film cathode proceeds by co-deposition of silver and yttria- stabilized zirconia. The sputter deposition of a thin film solid- oxide fuel cell is next demonstrated. The thin film fuel cell microstructure is examined using scanning electron microscopy whereas the cell performance is characterized through current-voltage measurement and corresponding impedance spectroscopy.

  12. Organosilane-functionalization of nanostructured indium tin oxide films.

    PubMed

    Pruna, R; Palacio, F; Martínez, M; Blázquez, O; Hernández, S; Garrido, B; López, M

    2016-12-06

    Fabrication and organosilane-functionalization and characterization of nanostructured ITO electrodes are reported. Nanostructured ITO electrodes were obtained by electron beam evaporation, and a subsequent annealing treatment was selectively performed to modify their crystalline state. An increase in geometrical surface area in comparison with thin-film electrodes area was observed by atomic force microscopy, implying higher electroactive surface area for nanostructured ITO electrodes and thus higher detection levels. To investigate the increase in detectability, chemical organosilane-functionalization of nanostructured ITO electrodes was performed. The formation of 3-glycidoxypropyltrimethoxysilane (GOPTS) layers was detected by X-ray photoelectron spectroscopy. As an indirect method to confirm the presence of organosilane molecules on the ITO substrates, cyclic voltammetry and electrochemical impedance spectroscopy (EIS) were also carried out. Cyclic voltammograms of functionalized ITO electrodes presented lower reduction-oxidation peak currents compared with non-functionalized ITO electrodes. These results demonstrate the presence of the epoxysilane coating on the ITO surface. EIS showed that organosilane-functionalized electrodes present higher polarization resistance, acting as an electronic barrier for the electron transfer between the conductive solution and the ITO electrode. The results of these electrochemical measurements, together with the significant difference in the X-ray spectra between bare ITO and organosilane-functionalized ITO substrates, may point to a new exploitable oxide-based nanostructured material for biosensing applications. As a first step towards sensing, rapid functionalization of such substrates and their application to electrochemical analysis is tested in this work. Interestingly, oxide-based materials are highly integrable with the silicon chip technology, which would permit the easy adaptation of such sensors into lab

  13. Degradation of superconducting Nb/NbN films by atmospheric oxidation

    DOE PAGES

    Henry, M. David; Wolfley, Steve; Young, Travis; ...

    2017-03-01

    Niobium and niobium nitride thin films are transitioning from fundamental research toward wafer scale manufacturing with technology drivers that include superconducting circuits and electronics, optical single photon detectors, logic, and memory. Successful microfabrication requires precise control over the properties of sputtered superconducting films, including oxidation. Previous work has demonstrated the mechanism in oxidation of Nb and how film structure could have deleterious effects upon the superconducting properties. This study provides an examination of atmospheric oxidation of NbN films. By examination of the room temperature sheet resistance of NbN bulk oxidation was identified and confirmed by secondary ion mass spectrometry. Asmore » a result, Meissner magnetic measurements confirmed the bulk oxidation not observed with simple cryogenic resistivity measurements.« less

  14. Nickel oxide nanoparticles film produced by dead biomass of filamentous fungus

    PubMed Central

    Salvadori, Marcia Regina; Nascimento, Cláudio Augusto Oller; Corrêa, Benedito

    2014-01-01

    The synthesis of nickel oxide nanoparticles in film form using dead biomass of the filamentous fungus Aspergillus aculeatus as reducing agent represents an environmentally friendly nanotechnological innovation. The optimal conditions and the capacity of dead biomass to uptake and produce nanoparticles were evaluated by analyzing the biosorption of nickel by the fungus. The structural characteristics of the film-forming nickel oxide nanoparticles were analyzed by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and atomic force microscopy (AFM). These techniques showed that the nickel oxide nanoparticles had a size of about 5.89 nm and were involved in a protein matrix which probably permitted their organization in film form. The production and uptake of nickel oxide nanoparticles organized in film form by dead fungal biomass bring us closer to sustainable strategies for the biosynthesis of metal oxide nanoparticles. PMID:25228324

  15. Nickel oxide nanoparticles film produced by dead biomass of filamentous fungus

    NASA Astrophysics Data System (ADS)

    Salvadori, Marcia Regina; Nascimento, Cláudio Augusto Oller; Corrêa, Benedito

    2014-09-01

    The synthesis of nickel oxide nanoparticles in film form using dead biomass of the filamentous fungus Aspergillus aculeatus as reducing agent represents an environmentally friendly nanotechnological innovation. The optimal conditions and the capacity of dead biomass to uptake and produce nanoparticles were evaluated by analyzing the biosorption of nickel by the fungus. The structural characteristics of the film-forming nickel oxide nanoparticles were analyzed by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and atomic force microscopy (AFM). These techniques showed that the nickel oxide nanoparticles had a size of about 5.89 nm and were involved in a protein matrix which probably permitted their organization in film form. The production and uptake of nickel oxide nanoparticles organized in film form by dead fungal biomass bring us closer to sustainable strategies for the biosynthesis of metal oxide nanoparticles.

  16. Evolution of nanostructure, defect-free photoluminescence and enhanced photoconductivity of oxidized Zn films

    NASA Astrophysics Data System (ADS)

    Koshy, Obey; Khadar, M. Abdul

    2011-06-01

    Nanostructured zinc oxide thin films were prepared by the oxidation of nanostructured zinc films deposited on glass substrates by thermal evaporation of metallic zinc in an atmosphere of nitrogen. The films were oxidized at different temperatures. X-ray diffraction was used to study the structural transformations of the films with oxidation temperature. Atomic force microscopy images of surface morphology of the films revealed the kinetics of aggregation of the grains as the oxidation temperature was increased. Raman spectra of the samples contained a surface mode at ˜482 cm-1 showing characteristics of fine grain size. UV-Visible absorption spectra of the samples showed a blueshift of bandgap in comparison with that of bulk ZnO crystals. The photoluminescence emission spectra of the samples were free from defect related emissions. The increase in oxidation temperature of these samples caused a narrowing of the photoluminescent emission band in the UV region and an increase in the UV photocurrent. The ratio of maximum photocurrent to dark current was found to increase from 100 to 2000 as the oxidation temperature of the films increased from 350 to 500 showing an enhanced photoconductivity. The increased photocurrent was attributed to the interconnected grain structure of the ZnO samples oxidized at higher temperature.

  17. Investigation of physicochemical and tribological properties of transparent oxide semiconducting thin films based on Ti-V oxides

    NASA Astrophysics Data System (ADS)

    Mazur, M.; Sieradzka, K.; Kaczmarek, D.; Domaradzki, J.; Wojcieszak, D.; Domanowski, P.

    2013-08-01

    In this paper investigations of structural and optical properties of nanocrystalline Ti-V oxide thin films are described. The films were deposited onto Corning 7059 glass using a modified reactive magnetron sputtering method. Structural investigations of prepared Ti-V oxides with vanadium addition of 19 at. % revealed amorphous structure, while incorporation of 21 and 23 at. % of vanadium resulted in V2O5 formation with crystallites sizes of 12.7 and 32.4 nm, respectively. All prepared thin films belong to transparent oxide semiconductors due to their high transmission level of ca. 60-75 % in the visible light range, and resistivity in the range of 3.3·102-1.4·105 Ωcm. Additionally, wettability and hardness tests were performed in order to evaluate the usefulness of the films for functional coatings.

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

    SciTech Connect

    Ou-Yang, Wei E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Mitoma, Nobuhiko; Kizu, Takio; Gao, Xu; Lin, Meng-Fang; Tsukagoshi, Kazuhito E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Nabatame, Toshihide

    2014-10-20

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

  19. Permeability and partitioning of ferrocene ethylene oxide and propylene oxide oligomers into electropolymerized films from acetonitrile and polyether solutions

    SciTech Connect

    Pyati, R.; Murray, R.W. )

    1994-10-27

    We report the first electrochemically-based measurements of the rates of small polymer permeation into another polymer. The small polymer permeants are ferrocene ethylene oxide oligomers containing 2, 7, and 16 units and a propylene oxide oligomer containing 3 units. Their permeation into ultrathin microelectrode-supported films of the metal complex polymer poly[Ru(vbpy)[sub 3

  20. Structure and Optical Properties of Nanocrystalline Hafnium Oxide Thin Films (PostPrint)

    DTIC Science & Technology

    2014-09-01

    AFRL-RX-WP-JA-2014-0214 STRUCTURE AND OPTICAL PROPERTIES OF NANOCRYSTALLINE HAFNIUM OXIDE THIN FILMS (POSTPRINT) Neil R. Murphy AFRL...OPTICAL PROPERTIES OF NANOCRYSTALLINE HAFNIUM OXIDE THIN FILMS (POSTPRINT) 5a. CONTRACT NUMBER In-House 5b. GRANT NUMBER 5c. PROGRAM ELEMENT...publication is available at http://dx.doi.org/10.1016/j.optmat.2014.08.005 14. ABSTRACT Hafnium oxide (HfO2) films were grown by sputter-deposition by

  1. Oxide Ceramic Films Grown on 60 Nitinol for NASA and Department of Defense Applications

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Street, Kenneth W.; Lukco, Dorothy; Cytron, Sheldon J.

    2005-01-01

    Both the NASA Glenn Research Center and the U.S. Army Research Laboratory, Development and Engineering Center (ARDEC) have worked to develop oxide ceramic films grown on 60 nitinol (60-wt% nickel and 40-wt% titanium) to decrease friction and increase wear resistance under unlubricated conditions. In general, oxide and nonoxide ceramic films have unique capabilities as mechanical-, chemical-, and thermal-barrier materials in diverse applications, including high-temperature bearings and gas bearings requiring low friction, wear resistance, and chemical stability. All oxide ceramic films grown on 60 nitinol were furnished by ARDEC, and materials and surface characterization and tribological experiments were conducted at Glenn.

  2. Effect of substrate temperature on structural and electrical properties of RF sputtered hafnium oxide thin films

    SciTech Connect

    Das, K. C.; Ghosh, S. P.; Tripathy, N.; Kar, J. P.; Bose, G.; Lee, T.; Myoung, J. M.

    2015-06-24

    In this work hafnium oxide thin films were deposited on p-type silicon substrate by Radio frequency magnetron sputtering at different substrate temperature ranging from room temperature to 300 °C. The structural and electrical properties of the sputtered films were investigated by x-ray diffraction, capacitance-voltage and current-voltage measurements. The XRD results show the formation monoclinic structure of the hafnium oxide thin films. The shifting of C-V curves towards negative voltage side depicts the increase in positive oxide charges with the rise of substrate temperature. Leakage current was found increased, when temperature enhanced from room temperature to 300 °C.

  3. Tribocorrosion behavior of biofunctional titanium oxide films produced by micro-arc oxidation: Synergism and mechanisms.

    PubMed

    Marques, Isabella da Silva Vieira; Alfaro, Maria Fernanda; Cruz, Nilson Cristino da; Mesquita, Marcelo Ferraz; Takoudis, Christos; Sukotjo, Cortino; Mathew, Mathew T; Barão, Valentim Adelino Ricardo

    2016-07-01

    Dental implants, inserted into the oral cavity, are subjected to a synergistic interaction of wear and corrosion (tribocorrosion), which may lead to implant failures. The objective of this study was to investigate the tribocorrosion behavior of Ti oxide films produced by micro-arc oxidation (MAO) under oral environment simulation. MAO was conducted under different conditions as electrolyte composition: Ca/P (0.3M/0.02M or 0.1M/0.03M) incorporated with/without Ag (0.62g/L) or Si (0.04M); and treatment duration (5 and 10min). Non-coated and sandblasted samples were used as controls. The surfaces morphology, topography and chemical composition were assessed to understand surface properties. ANOVA and Tukey׳s HSD tests were used (α=0.05). Biofunctional porous oxide layers were obtained. Higher Ca/P produced larger porous and harder coatings when compared to non-coated group (p<0.001), due to the presence of rutile crystalline structure. The total mass loss (Kwc), which includes mass loss due to wear (Kw) and that due to corrosion (Kc) were determined. The dominant wear regime was found for higher Ca/P groups (Kc/Kw≈0.05) and a mechanism of wear-corrosion for controls and lower Ca/P groups (Kc/Kw≈0.11). The group treated for 10min and enriched with Ag presented the lowest Kwc (p<0.05). Overall, MAO process was able to produce biofunctional oxide films with improved surface features, working as tribocorrosion resistant surfaces. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Induction of superconductivity of a La2CuO4 thin film chemically oxidized by NaClO

    NASA Astrophysics Data System (ADS)

    Wang, C. C.; Cui, M. L.; Zheng, X.; Zhu, J.

    High-quality, c-axis-oriented La2CuO4 thin films have been fabricated by the pulsed laser ablation technique. Superconductivity has been successfully induced in the films after chemical oxidation using sodium hypochlorite solution as oxidizing agent. The structural properties, surface morphology, and electrical resistivity before and after oxidation are compared. In addition, the oxidation mechanism is discussed.

  5. Fabrication of protective over layer for enhanced thermal stability of zinc oxide based TCO films

    NASA Astrophysics Data System (ADS)

    Ravichandran, K.; Ravikumar, P.; Sakthivel, B.

    2013-12-01

    To prevent the loss of oxygen vacancies in aluminium doped zinc oxide (AZO) thin films at high temperature process, and to enhance the thermal stability a protective tin oxide (TO) over layer has been realized. To investigate the protective nature of doped tin oxide layer, fluorine doped tin oxide (FTO) and antimony doped tin oxide (ATO) layers have also been coated on AZO layer. Then, to confirm its stability of opto-electrical properties under high temperature process, structural, optical and electrical studies of AZO single layer, TO/AZO, FTO/AZO and ATO/AZO double layered films were carried out before and after annealing and the results are reported. The XRD results showed that the crystalline nature of double layered films remains unchanged, even after the heat treatment. The UV results depicted that, in all the double layer films the transmission spectra remain unchanged or changed negligibly after annealing, indicating the thermal stability of double layered films. The photoluminescence results also strongly supported the improvement in the thermal stability of double layered films. The electrical studies suggested that the double layered films exhibited better electrical resistivity with bare AZO films.

  6. Calcium-Mediated Control of Polydopamine Film Oxidation and Iron Chelation

    PubMed Central

    Klosterman, Luke; Bettinger, Christopher J.

    2016-01-01

    The facile preparation of conformal polydopamine (PDA) films on broad classes of materials has prompted extensive research into a wide variety of potential applications for PDA. The constituent molecular species in PDA exhibit diverse chemical moieties, and therefore highly variable properties of PDA-based devices may evolve with post-processing conditions. Here we report the use of redox-inactive cations for oxidative post-processing of deposited PDA films. PDA films incubated in alkaline CaCl2 solutions exhibit accelerated oxidative evolution in a dose-dependent manner. PDA films incubated in CaCl2 solutions exhibit 53% of the oxidative charge transfer compared to pristine PDA films. Carboxylic acid groups generated from the oxidation process lower the isoelectric point of PDA films from pH = 4.0 ± 0.2 to pH = 3.1 ± 0.3. PDA films exposed to CaCl2 solutions during post-processing also enhance Fe2+/Fe3+ chelation compared to pristine PDA films. These data illustrate that the molecular heterogeneity and non-equilibrium character of as-deposited PDA films afford control over the final composition by choosing post-processing conditions, but also demands forethought into how the performance of PDA-incorporated devices may change over time in salt solutions. PMID:28025498

  7. Calcium-Mediated Control of Polydopamine Film Oxidation and Iron Chelation.

    PubMed

    Klosterman, Luke; Bettinger, Christopher J

    2016-12-22

    The facile preparation of conformal polydopamine (PDA) films on broad classes of materials has prompted extensive research into a wide variety of potential applications for PDA. The constituent molecular species in PDA exhibit diverse chemical moieties, and therefore highly variable properties of PDA-based devices may evolve with post-processing conditions. Here we report the use of redox-inactive cations for oxidative post-processing of deposited PDA films. PDA films incubated in alkaline CaCl₂ solutions exhibit accelerated oxidative evolution in a dose-dependent manner. PDA films incubated in CaCl₂ solutions exhibit 53% of the oxidative charge transfer compared to pristine PDA films. Carboxylic acid groups generated from the oxidation process lower the isoelectric point of PDA films from pH = 4.0 ± 0.2 to pH = 3.1 ± 0.3. PDA films exposed to CaCl₂ solutions during post-processing also enhance Fe(2+)/Fe(3+) chelation compared to pristine PDA films. These data illustrate that the molecular heterogeneity and non-equilibrium character of as-deposited PDA films afford control over the final composition by choosing post-processing conditions, but also demands forethought into how the performance of PDA-incorporated devices may change over time in salt solutions.

  8. Thermally evaporated mechanically hard tin oxide thin films for opto-electronic apllications

    SciTech Connect

    Tripathy, Sumanta K.; Rajeswari, V. P.

    2014-01-28

    Tungsten doped tin oxide (WTO) and Molybdenum doped tin oxide (MoTO) thin film were deposited on corn glass by thermal evaporation method. The films were annealed at 350°C for one hour. Structural analysis using Xray diffraction data shows both the films are polycrystalline in nature with monoclinic structure of tin oxide, Sn{sub 3}O{sub 4}, corresponding to JCPDS card number 01-078-6064. SEM photograph showed that both the films have spherical grains with size in the range of 20–30 nm. Compositional analysis was carried out using EDS which reveals the presence of Sn, O and the dopant Mo/W only thereby indicating the absence of any secondary phase in the films. The films are found to contain nearly 6 wt% of Mo, 8 wt% of W as dopants respectively. The transmission pattern for both the films in the spectral range 200 – 2000 nm shows that W doping gives a transparency of nearly 80% from 380 nm onwards while Mo doping has less transparency of 39% at 380nm. Film hardness measurement using Triboscope shows a film hardness of about 9–10 GPa for both the films. It indicates that W or M doping in tin oxide provides the films the added advantage of withstanding the mechanical wear and tear due to environmental fluctuations By optimizing the optical and electrical properties, W/Mo doped tin oxide films may be explored as window layers in opto-electronic applications such as solar cells.

  9. Oxide-based method of making compound semiconductor films and making related electronic devices

    DOEpatents

    Kapur, Vijay K.; Basol, Bulent M.; Leidholm, Craig R.; Roe, Robert A.

    2000-01-01

    A method for forming a compound film includes the steps of preparing a source material, depositing the source material on a base and forming a preparatory film from the source material, heating the preparatory film in a suitable atmosphere to form a precursor film, and providing suitable material to said precursor film to form the compound film. The source material includes oxide-containing particles including Group IB and IIIA elements. The precursor film includes non-oxide Group IB and IIIA elements. The compound film includes a Group IB-IIIA-VIA compound. The oxides may constitute greater than about 95 molar percent of the Group IB elements and greater than about 95 molar percent of the Group IIIA elements in the source material. Similarly, non-oxides may constitute greater than about 95 molar percent of the Group IB elements and greater than about 95 molar percent of the Group IIIA elements in the precursor film. The molar ratio of Group IB to Group IIIA elements in the source material may be greater than about 0.6 and less than about 1.0, or substantially greater that 1.0, in which case this ratio in the compound film may be reduced to greater than about 0.6 and less than about 1.0. The source material may be prepared as an ink from particles in powder form. The oxide-containing particles may include a dopant, as may the compound film. Compound films including a Group IIB-IVA-VA compound may be substituted using appropriate substitutions in the method. The method, also, is applicable to fabrication of solar cells and other electronic devices.

  10. Aqueous process to limit hydration of thin-film inorganic oxides

    NASA Astrophysics Data System (ADS)

    Perkins, Cory K.; Mansergh, Ryan H.; Park, Deok-Hie; Nanayakkara, Charith E.; Ramos, Juan C.; Decker, Shawn R.; Huang, Yu; Chabal, Yves J.; Keszler, Douglas A.

    2016-11-01

    Aqueous-processed aluminum oxide phosphate (AlPO) dielectric films were studied to determine how water desorbs and absorbs on heating and cooling, respectively. In-situ Fourier transform infrared spectroscopy showed a distinct, reversible mono- to bidentate phosphate structural change associated with water loss and uptake. Temperature programmed desorption measurements on a 1-μm thick AlPO film revealed water sorption was inhibited by an aqueous-processed HfO2 capping film only 11-nm thick. The HfO2 capping film prevents water resorption, thereby preserving the exceptional performance of AlPO as a thin-film dielectric.

  11. Chemical and optical properties of thermally evaporated manganese oxide thin films

    SciTech Connect

    Al-Kuhaili, M. F.

    2006-09-15

    Manganese oxide thin films were deposited using thermal evaporation from a tungsten boat. Films were deposited under an oxygen atmosphere, and the effects of thickness, substrate temperature, and deposition rate on their properties were investigated. The chemical properties of the films were studied using x-ray photoelectron spectroscopy and x-ray fluorescence. The optical properties were determined from normal-incidence transmittance and reflectance. Based on the chemical and optical characterizations, the optimum conditions for the deposition of the films were investigated. Subsequently, the optical properties (refractive index, extinction coefficient, and band gap) of these films were determined.

  12. An oxidation-last annealing for enhancing the reliability of indium-gallium-zinc oxide thin-film transistors

    NASA Astrophysics Data System (ADS)

    Li, Jiapeng; Lu, Lei; Feng, Zhuoqun; Kwok, Hoi Sing; Wong, Man

    2017-04-01

    The dependence of device reliability against a variety of stress conditions on the annealing atmosphere was studied using a single metal-oxide thin-film transistor with thermally induced source/drain regions. A cyclical switch between an oxidizing and a non-oxidizing atmosphere induced a regular change in the stress-induced shift of the turn-on voltage, with the magnitude of the shift being consistently smaller after annealing in an oxidizing atmosphere. The observed behavior is discussed in terms of the dependence of the population of oxygen vacancies on the annealing atmosphere, and it is recommended the last of the sequence of thermal processes applied to a metal-oxide thin-film transistor be executed in an oxidizing atmosphere.

  13. Preparation Of Electrochromic Metal Oxide Films By Plasma-Enhanced Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Benson, D. K.; Tracy, C. E.; Svensson, J. S. E. M.; Liebert, B. E.

    1987-11-01

    Laboratory procedures have been developed for depositing thin films of electrochromic metal oxides by plasma-enhanced chemical vapor deposition (PE-CVD). In this process, vapor phase reactants, such as tungsten hexafluotIde, are mixed with oxygen and excited by RF energy at a frequency of 13.56 MHz and power levels up to≍1W/cm2 substrate area. Large rates of oxide deposition have been achieved (> 8 nm/s) making this process a candidate for high-speed coating of large area substrates, such as window glass. Amorphous WO1 films prepared by PE-CVD have been shown to have electrochromic responses virtually identical to films prepared by vacuum evaporation. The lithium ion diffusion rate, for example, is approximately 1.3 x 10-11 cm2 /s at x = 0.03 in LixWO3 prepared by PE-CVD. On the other hand, molybdenum oxide films and mixed molybdenum/tungsten oxide films prepared by PE-CVD from the hexafluorides differ markedly from vacuum evaporated films. Their electrochromic responses are spectrally different and are much slower. Lithium ion diffusion rates in such Mo03 films are lower by about three orders of magnitude. These differences are tentatively attributed to a large fraction of fluorine (Mo:F ratios of the order of 2:1) which are incorporated into the molybdenum and mixed oxides, but are not incorporated into the tungsten oxides.

  14. Preparation of reduced graphene oxide/gelatin composite films with reinforced mechanical strength

    SciTech Connect

    Wang, Wenchao; Wang, Zhipeng; Liu, Yu; Li, Nan; Wang, Wei; Gao, Jianping

    2012-09-15

    Highlights: ► We used and compared different proportion of gelatin and chitosan as reducing agents. ► The mechanical properties of the films are investigated, especially the wet films. ► The cell toxicity of the composite films as biomaterial is carried out. ► The water absorption capabilities of the composite films also studied. -- Abstract: Graphene oxide (GO) was reduced by chitosan/gelatin solution and added to gelatin (Gel) to fabricate reduced graphene oxide/gelatin (RGO/Gel) films by a solvent-casting method using genipin as cross-linking agent. The structure and properties of the films were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA) and UV–vis spectroscopy. The addition of RGO increased the tensile strength of the RGO/Gel films in both dry and wet states, but decreased their elongation at break. The incorperation of RGO also decreased the swelling ability of the films in water. Cell cultures were carried out in order to test the cytotoxicity of the films. The cells grew and reproduced well on the RGO/Gel films, indicating that the addition of RGO has no negative effect on the compatibility of the gelatin. Therefore, the reduced graphene oxide/gelatin composite is a promising biomaterial with excellent mechanical properties and good cell compatibility.

  15. Electrochromic characteristics of niobium-doped titanium oxide film on indium tin oxide/glass by liquid phase deposition

    NASA Astrophysics Data System (ADS)

    Lee, Ming-Kwei; Lee, Chia-Jung

    2015-10-01

    Ammonium hexafluorotitanate and boric acid aqueous solutions were used as precursors for the growth of titanium oxide films on indium tin oxide (ITO)/glass substrate. For as-grown titanium oxide film used in an electrochromic device, Li+ ions from electrolyte will be trapped to hydroxyl groups and degrade the electrochromic durability during the cyclic voltammogram characterization. For niobium doped titanium oxide film, lower growth rate from more HF incorporation from the niobium doped solution and rougher surface morphology from the formation of nanocrystals were obtained. However, niobium doping reduces hydroxyl groups and the electrochromic durability is enhanced from 5 × 103 to 1 × 104 times. The transmittance is enhanced from 37 to 51% at the wavelength of 550 nm.

  16. Thin films of metal oxides on metal single crystals: Structure and growth by scanning tunneling microscopy

    SciTech Connect

    Galloway, Heather Claire

    1995-12-01

    Detailed studies of the growth and structure of thin films of metal oxides grown on metal single crystal surfaces using Scanning Tunneling Microscopy (STM) are presented. The oxide overlayer systems studied are iron oxide and titanium oxide on the Pt(III) surface. The complexity of the metal oxides and large lattice mismatches often lead to surface structures with large unit cells. These are particularly suited to a local real space technique such as scanning tunneling microscopy. In particular, the symmetry that is directly observed with the STM elucidates the relationship of the oxide overlayers to the substrate as well as distinguishing, the structures of different oxides.

  17. Low Temperature Constrained Sintering of Cerium Gadolinium OxideFilms for Solid Oxide Fuel Cell Applications

    SciTech Connect

    Nicholas, Jason Dale

    2007-01-01

    Cerium gadolinium oxide (CGO) has been identified as an acceptable solid oxide fuel cell (SOFC) electrolyte at temperatures (500-700 C) where cheap, rigid, stainless steel interconnect substrates can be used. Unfortunately, both the high sintering temperature of pure CGO, >1200 C, and the fact that constraint during sintering often results in cracked, low density ceramic films, have complicated development of metal supported CGO SOFCs. The aim of this work was to find new sintering aids for Ce0.9Gd0.1O1.95, and to evaluate whether they could be used to produce dense, constrained Ce0.9Gd0.1O1.95 films at temperatures below 1000 C. To find the optimal sintering aid, Ce0.9Gd0.1O1.95 was doped with a variety of elements, of which lithium was found to be the most effective. Dilatometric studies indicated that by doping CGO with 3mol% lithium nitrate, it was possible to sinter pellets to a relative density of 98.5% at 800 C--a full one hundred degrees below the previous low temperature sintering record for CGO. Further, it was also found that a sintering aid's effectiveness could be explained in terms of its size, charge and high temperature mobility. A closer examination of lithium doped Ce0.9Gd0.1O1.95 indicated that lithium affects sintering by producing a Li2O-Gd2O3-CeO2 liquid at the CGO grain boundaries. Due to this liquid phase sintering, it was possible to produce dense, crack-free constrained films of CGO at the record low temperature of 950 C using cheap, colloidal spray deposition processes. This is the first time dense constrained CGO films have been produced below 1000 C and could help commercialize metal supported ceria based solid oxide fuel cells.

  18. Structural, optical and electrical properties of yttrium-doped hafnium oxide nanocrystalline thin films

    NASA Astrophysics Data System (ADS)

    Kongu, Abhilash

    Hafnium oxide (HfO2) has emerged as the most promising high-k dielectric for Metal-Oxide-Semiconductor (MOS) devices and has been highlighted as the most suitable dielectric materials to replace silicon oxide because of its comprehensive performance. In the present research, yttrium-doped HfO2 (YDH) thin films were fabricated using RF magnetron sputter deposition onto Si (100) and quartz with a variable thickness. Cross-sectional scanning electron microscopy coupled with Filmetrics revealed that film thickness values range from 700 A° to 7500 A°. Electrical properties such as AC Resistivity and current-voltage (I-V) characteristics of YDH films were studied. YDH films that were relatively thin (<1500 A°) crystallized in monoclinic phase while thicker films crystallized in cubic phase. The band gap (Eg) of the films was calculated from the optical measurements. The band gap was found to be ˜5.60 eV for monoclinic while it is ˜6.05 eV for cubic phase of YDH films. Frequency dependence of the electrical resistivity (rhoac) and the total conductivity of the films were measured. Resistivity decreased (by three orders of magnitude) with increasing frequency from 100 Hz to 1 MHz, attributed due to the hopping mechanism in YDH films. Whereas, while rhoac˜1O-m at low frequencies (100 Hz), it decreased to ˜ 104 O-cm at higher frequencies (1 MHz). Aluminum (Al) metal electrodes were deposited to fabricate a thin film capacitor with YDH layer as dielectric film thereby employing Al-YDH-Si capacitor structure. The results indicate that the capacitance of the films decrease with increasing film thickness. A detailed analysis of the electrical characteristics of YDH films is presented.

  19. Quantitative analysis of oxygen content in copper oxide films using ultra microbalance

    SciTech Connect

    Shu, Yonghua; Wang, Lianhong; Liu, Chong; Fan, Jing

    2014-12-09

    Copper oxide films were prepared on quartz substrates through electron beam physical vapor deposition in a vacuum chamber, and the films were observed using X-ray diffraction (XRD) and scanning electron microscope (SEM). The oxygen content of the films were analyzed using an ultra microbalance. Results indicated that when the substrate was heated to 600°C and the oxygen flow rate was 5 sccm, the film was composed of 47% Cu and 53% Cu2O (mass percent), and the oxidation ratio of copper was 25%. After the deposition process at the same condition, i.e. the substrate at temperature of 600°C and blowed by oxygen flowrate of 5 sccm, then in-stu annealed at 600°C in low oxygen pressure of 10 Pa for 30 minutes, the film composition became 22% Cu2O and 78% CuO (mass percent), and the oxidation ratio of copper greatly increased to about 88%.

  20. Effects of process parameters on sheet resistance uniformity of fluorine-doped tin oxide thin films.

    PubMed

    Hudaya, Chairul; Park, Ji Hun; Lee, Joong Kee

    2012-01-05

    An alternative indium-free material for transparent conducting oxides of fluorine-doped tin oxide [FTO] thin films deposited on polyethylene terephthalate [PET] was prepared by electron cyclotron resonance - metal organic chemical vapor deposition [ECR-MOCVD]. One of the essential issues regarding metal oxide film deposition is the sheet resistance uniformity of the film. Variations in process parameters, in this case, working and bubbler pressures of ECR-MOCVD, can lead to a change in resistance uniformity. Both the optical transmittance and electrical resistance uniformity of FTO film-coated PET were investigated. The result shows that sheet resistance uniformity and the transmittance of the film are affected significantly by the changes in bubbler pressure but are less influenced by the working pressure of the ECR-MOCVD system.

  1. Erosion of a-C:H films under interaction with nitrous oxide afterglow discharge

    NASA Astrophysics Data System (ADS)

    Zalavutdinov, R. Kh.; Gorodetsky, A. E.; Bukhovets, V. L.; Zakharov, A. P.; Mazul, I. V.

    2009-06-01

    Hydrocarbon film removal using chemically active oxygen formed in a direct current glow discharge with a hollow cathode in nitrous oxide was investigated. In the afterglow region sufficiently fast removal of a-C:H films about 500 nm thick during about 8 h was achieved at N 2O pressure of 12 Pa and 370 K. The erosion rate in the afterglow region was directly proportional to the initial pressure and increased two orders of magnitude at temperature rising from 300 to 500 K. The products of a-C:H film plasmolysis were CO, CO 2, H 2O, and H 2. After removal of a-C:H films previously deposited on stainless steel, molybdenum or tungsten 3-30 nm thick oxide films were formed on the substrates. Reactions of oxygen ion neutralization and atomic oxygen recombination suppressed further oxidation of the materials.

  2. Cholesterol photosensitised oxidation of horse meat slices stored under different packaging films.

    PubMed

    Boselli, Emanuele; Rodriguez-Estrada, Maria Teresa; Ferioli, Federico; Caboni, Maria Fiorenza; Lercker, Giovanni

    2010-07-01

    The effect of the type of packaging film (transparent vs. light-protecting red film) was evaluated on the formation of cholesterol oxidation products (COPs) in refrigerated horse meat slices stored in retail conditions under light exposure for 8h. In meat wrapped with a transparent film, COPs increased from 233 (control) to 317 microg/g of fat, whereas the red film delayed cholesterol oxidation and offered protection against COPs formation, since COPs decreased from 173 (control) to 139 microg/g of fat after 8h of light exposure. In addition, light opened the epoxy ring and led to the formation of triol, which was actually absent at T(0.) A proper packaging film may represent a useful strategy to retard oxidative degradation in a light-sensitive, high pigment- and fat-containing food, such as horse meat.

  3. Sputtered cadmium oxide as a surface pretreatment for graphite solid lubricant films

    NASA Technical Reports Server (NTRS)

    Fusaro, R. L.

    1986-01-01

    Sputtered films of cadmium oxide were applied to sand blasted AISI 440C HT stainless steel disks as a surface pretreatment for the application of rubbed graphite films. Mixtures of cadmium oxide and graphite were applied to the nonpretreated sandblasted metal and evaluated. The results were compared to graphite films applied to other commercially available surface pretreatments. It is found that sputtered CdO pretreated surfaces increase the endurance lives of the graphite films and decrease the counterface steady state wear rate of the pins almost an order of magnitude compared to commercially available pretreatments. The CdO additions in general improved the tribological properties of graphite. The greatest benefit occurred when it was applied to the substrate rather than mixing it with the graphite and that sputtered films of CdO perform much better than rubbed CdO films.

  4. Preparation and characterization of tungsten oxide thin films with high electrochromic performance

    NASA Astrophysics Data System (ADS)

    Lv, Gang; Wu, Yonggang; Wu, Heyun; Ling, Leijie; Xia, Zihuan

    2010-10-01

    Tungsten oxide thin films were prepared by depositing WO3 onto glass substrates coated with ITO using reactive evaporation process at ambient temperature and 200°C respectively. The thin films were grown at different deposition rate. Chronoamperometry was carried out and spectral measurements were performed in situ. Results showed that the thin films prepared at low deposition rates possess higher coloration efficiency (CE), and the thin films grown at ambient temperature have high CE than those grown at 200°C. The origin of the differences in coloration efficiency of the thin films were analyzed and discussed based on the electrochromic mechanism of amorphous tungsten oxide films. The samples morphology was characterized by atom force microscopy (AFM).

  5. Preparation and characterization of tungsten oxide thin films with high electrochromic performance

    NASA Astrophysics Data System (ADS)

    Lv, Gang; Wu, Yonggang; Wu, Heyun; Ling, Leijie; Xia, Zihuan

    2011-02-01

    Tungsten oxide thin films were prepared by depositing WO3 onto glass substrates coated with ITO using reactive evaporation process at ambient temperature and 200°C respectively. The thin films were grown at different deposition rate. Chronoamperometry was carried out and spectral measurements were performed in situ. Results showed that the thin films prepared at low deposition rates possess higher coloration efficiency (CE), and the thin films grown at ambient temperature have high CE than those grown at 200°C. The origin of the differences in coloration efficiency of the thin films were analyzed and discussed based on the electrochromic mechanism of amorphous tungsten oxide films. The samples morphology was characterized by atom force microscopy (AFM).

  6. Electrochromic properties of vanadium oxide thin films prepared by PSPT: Effect of substrate temperature

    NASA Astrophysics Data System (ADS)

    Patil, C. E.; Jadhav, P. R.; Tarwal, N. L.; Deshmukh, H. P.; Karanjakar, M. M.; Wali, A. A.; Patil, P. S.

    2013-06-01

    Electrochromic vanadium oxide (V2O5) thin films were deposited onto glass and fluorine doped tin oxide (FTO) coated glass substrates from methanolic vanadium chloride solution by pulsed spray pyrolysis technique (PSPT). The films were synthesized at different substrate temperatures ranging from 350°C-450°C with a temperature step of 50°C. The structural, morphological, optical and electrochromic properties of the synthesized films were investigated. The films were polycrystalline with tetragonal crystal structure. Scanning electron microscopy reveals compact morphology at high temperature. All films exhibited cathodic electrochromism in lithium containing electrolyte (0.5 M LiClO4 + Propylene Carbonate). Maximum coloration efficiency (CE) 15.16 cm2C-1, was observed for the films deposited at 350°C.

  7. Formation of particulate Fe-Al films by selective oxidation of aluminum

    NASA Astrophysics Data System (ADS)

    Jang, Pyungwoo; Shin, Seung Chan

    2013-09-01

    Fe-5wt%Al films were RF-sputtered and annealed in an atmosphere of hydrogen and water vapor mixture at 1173 K for up to 200 min in order to selectively oxidize aluminum. As the annealing time increased, the morphology of the films changed from the continuous to the discontinuous type; thus, particulate Fe-Al films formed after 100 min. Thermodynamics simulation was performed to determine the ideal conditions for this process. Temperatures exceeding 1073 K are necessary to prevent iron from oxidation confirmed by both the depth profile in XPS and magnetic moment increment in VSM. Annealing the films in an atmosphere with a very low dew point of 77 K did not make the films become particulate. New findings are expected to be applied to the thin film inductors for GHz application as well as to manufacturing process of nanoparticles.

  8. Sputtered cadmium oxide as a surface pretreatment for graphite solid-lubricant films

    NASA Technical Reports Server (NTRS)

    Fusaro, Robert L.

    1987-01-01

    Sputtered films of cadmium oxide were applied to sand blasted AISI 440C HT stainless steel disks as a surface pretreatment for the application of rubbed graphite films. Mixtures of cadmium oxide and graphite were applied to the nonpretreated sandblasted metal and evaluated. The results were compared to graphite films applied to other commercially available surface pretreatments. It is found that sputtered CdO pretreated surfaces increase the endurance lives of the graphite films and decrease the counterface steady state wear rate of the pins almost an order of magnitude compared to commercially available pretreatments. The CdO additions in general improved the tribological properties of graphite. The greatest benefit occurred when it was applied to the substrate rather than mixing it with the graphite and that sputtered films of CdO perform much better than rubbed CdO films.

  9. Transpassive Dissolution of Copper and Rapid Formation of Brilliant Colored Copper Oxide Films

    NASA Astrophysics Data System (ADS)

    Fredj, Narjes; Burleigh, T. David; New Mexico Tech Team

    2014-03-01

    This investigation describes an electrochemical technique for growing adhesive copper oxide films on copper with attractive colors ranging from gold-brown to pearl with intermediate colors from red violet to gold green. The technique consists of anodically dissolving copper at transpassive potentials in hot sodium hydroxide, and then depositing brilliant color films of Cu2O onto the surface of copper after the anodic potential has been turned off. The color of the copper oxide film depends on the temperature, the anodic potential, the time t1 of polarization, and the time t2, which is the time of immersion after potential has been turned off. The brilliant colored films were characterized using glancing angle x-ray diffraction, and the film was found to be primarily Cu2O. Cyclic voltammetry, chronopotentiometry, scanning electron microscopy, and x-ray photoelectron spectroscopy were also used to characterize these films.

  10. Controlling preferred orientation and electrical conductivity of zinc oxide thin films by post growth annealing treatment

    NASA Astrophysics Data System (ADS)

    Kennedy, J.; Murmu, P. P.; Leveneur, J.; Markwitz, A.; Futter, J.

    2016-03-01

    We report the microstructural evolution of the preferred orientation and electrical conductivity of zinc oxide (ZnO) thin films prepared by ion beam sputtering. Elastic recoil detection analysis results showed 0.6 at% H in as-deposited film which decreased to 0.35 at% in air annealed film due to H diffusion. XRD results showed that the preferred orientation can be tuned by selecting annealing conditions. Vacuum annealed films exhibited (1 0 0) orientation, whereas air annealed film showed (0 0 2) orientation. The annealing conditions caused a dramatic increase in the resistivity of air annealed films (∼106 Ω cm), whereas vacuum annealed films showed lower resistivity (∼10-2 Ω cm). High resistivity in air annealed film is attributed to the lack of hydrogen interstitials and hydrogen-oxygen vacancy complexes. Raman results supported the XRD results which demonstrated that annealing assisted in recovery of the crystalline disorder in as-deposited films. Air annealed film exhibited the highest optical transmission (89.7%) in the UV-vis region compared to as-deposited and vacuum annealed films (∼85%). Optical bandgap was found to vary between 3.11 eV and 3.18 eV in as-deposited and annealed films, respectively. The bandgap narrowing is associated with the intrinsic defects which introduced defect states resulting in band tail in ZnO films.

  11. Sputtered iridium oxide films (SIROFs) for low-impedance neural stimulation and recording electrodes.

    PubMed

    Cogan, S F; Plante, T D; Ehrlich, J

    2004-01-01

    Iridium oxide films formed by electrochemical activation of iridium metal (AIROF) or by electrochemical deposition (EIROF) are being evaluated as low-impedance charge-injection coatings for neural stimulation and recording. Iridium oxide may also be deposited by reactive sputtering from iridium metal in an oxidizing plasma. The characterization of sputtered iridium oxide films (SIROFs) as coatings for nerve electrodes is reported. SIROFs were characterized by cyclic voltammetry, electrochemical impedance spectroscopy, and potential transient measurements during charge-injection. The surface morphology of the SIROF transitions from smooth to highly nodular with increasing film thickness from 80 nm to 4600 nm. Charge-injection capacities exceed 0.75 mC/cm(2) with 0.75 ms current pulses in thicker films. The SIROF was deposited on both planar and non-planar substrates and photolithographically patterned by lift-off.

  12. Substrate and laser power dependence of surface-enhanced Raman scattering from a silver oxide film.

    PubMed

    Iwanabe, Yasuhiko; Fujimaki, Makoto; Awazu, Koichi; Horiuchi, Toshiyuki; Tominaga, Junji

    2006-03-28

    We report a method to improve the efficiency of surface-enhanced Raman scattering (SERS) from a silver oxide film. A 632.8 nm He-Ne laser beam was focused on silver oxide films deposited on different substrates (silica, TiO2, Si). We found that the substrate material greatly affected the SERS efficiency, and that silica substrate showed the highest efficiency among the materials measured. Scanning electron microscopy observations revealed that silver nanoparticles were generated within the focused laser spot. Computer simulations of the thermal profile based upon data from experimental observations were also carried out. It was found that the temperature of the silver oxide film differed greatly according to the substrate. We infer that substrates that allow higher silver-oxide-film temperatures to be attained are more suitable for efficient SERS.

  13. Effects of Graphene Oxide Addition on Mechanical and Thermal Properties of Evoh Films

    NASA Astrophysics Data System (ADS)

    González-Ruiz, Jesús; Yataco-Lazaro, Lourde; Virginio, Sueli; das Graças da Silva-Valenzuela, Maria; Moura, Esperidiana; Valenzuela-Díaz, Francisco

    Currently, ethylene vinyl alcohol (EVOH) is one of the oxygen barrier materials most used for food packaging. The addition of graphene oxide nanosheets to the EVOH matrix is employed to improve their mechanic al and barrier properties. In this work, films of EVOH-based composites reinforced with graphene oxide were prepared by melt extrusion, using a twin screw extruder machine and blown extrusion process. The graphene oxide was prepared via chemical oxidation of natural graphite and then was exfoliated into nanosheets using the sonochemical method. The composite films samples were characterized using FTIR and DSC analysis. In addition, their mechanical properties were also determined.

  14. Evaluation of solution-processed reduced graphene oxide films as transparent conductors.

    PubMed

    Becerril, Héctor A; Mao, Jie; Liu, Zunfeng; Stoltenberg, Randall M; Bao, Zhenan; Chen, Yongsheng

    2008-03-01

    Processable, single-layered graphene oxide (GO) is an intriguing nanomaterial with tremendous potential for electronic applications. We spin-coated GO thin-films on quartz and characterized their sheet resistance and optical transparency using different reduction treatments. A thermal graphitization procedure was most effective, producing films with sheet resistances as low as 10(2) -10(3) Omega/square with 80% transmittance for 550 nm light. Our experiments demonstrate solution-processed GO films have potential as transparent electrodes.

  15. Submicron Nb-Al/Al oxide-Nb tunnel junctions sandwiched between Al films

    NASA Astrophysics Data System (ADS)

    Maier, D.; Rothermel, H.; Gundlach, K. H.; Zimmermann, R.

    1996-02-01

    A process has been developed to embed Nb-Al/Al oxide-Nb junctions in planar structures of Al films. The submicron junctions are defined by photoresist lines. Motivation for this effort is a possible application of Nb junctions confined between normal conducting Al films as mixers above 700 GHz where Nb films loose their superconductive properties and tuning circuits made out of Nb therefore exhibit losses. First mixer results at 816 GHz are presented.

  16. Transparent and Conductive Cadmium-Tin Oxide Films Deposited by Atom Beam Sputtering

    NASA Astrophysics Data System (ADS)

    Nakazawa, Tatsuo; Ito, Kentaro

    1988-09-01

    Transparent and conductive cadmium-tin oxide films with resistivities of 9× 10-4 Ω cm and transmittance higher than 80% over the visible range were prepared by atom beam sputtering. The structure of the deposited film was amorphous and its composition was highly deficient in CdO compared with Cd2SnO4. This CTO film was used as the window layer of a heterojunction solar cell.

  17. Bioinspired, Ultrastrong, Highly Biocompatible, and Bioactive Natural Polymer/Graphene Oxide Nanocomposite Films.

    PubMed

    Zhu, Wen-Kun; Cong, Huai-Ping; Yao, Hong-Bin; Mao, Li-Bo; Asiri, Abdullah M; Alamry, Khalid A; Marwani, Hadi M; Yu, Shu-Hong

    2015-09-09

    Tough and biocompatible nanocomposite films: A new type of bioinspired ultrastrong, highly biocompatible, and bioactive konjac glucomannan (KGM)/graphene oxide (GO) nanocomposite film is fabricated on a large scale by a simple solution-casting method. Such KGM-GO composite films exhibit much enhanced mechanical properties under the strong hydrogen-bonding interactions, showing great potential in the fields of tissue engineering and food package. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Oxide film defects in Al alloys and the formation of hydrogen- related porosity

    NASA Astrophysics Data System (ADS)

    Griffiths, W. D.; Gerrard, A. J.; Yue, Y.

    2016-03-01

    Double oxide film defects have also been held responsible for the origins of hydrogen porosity, where hydrogen dissolved in the Al melt passes into the interior atmosphere of the double oxide film defect causing it to inflate. However, this is in opposition to long- established evidence that H cannot readily diffuse through aluminium oxide. To investigate this further, samples of commercial purity Al were first degassed to remove their initial H content, and then heated to above their melting point and held in atmospheres of air and nitrogen respectively, to determine any differences in H pick-up. The experiment showed that samples held in an oxidising atmosphere, and having an oxide skin, picked up significantly less H than when the samples were held in a nitrogen atmosphere, which resulted in the formation of AlN in cracks in the oxide skin of the sample. It is suggested that double oxide film defects can give rise to hydrogen-related porosity, but this occurs more quickly when the oxygen in the original oxide film defect has been consumed by reaction with the surrounding melt and nitrogen reacts to form AlN, which is more permeable to H than alumina, more easily allowing the oxide film defect to give rise to a hydrogen pore. This is used to interpret results from an earlier synchrotron experiment, in which a small pore was seen to grow into a larger pore, while an adjacent large pore remained at a constant size.

  19. P-channel thin film transistors using reduced graphene oxide

    NASA Astrophysics Data System (ADS)

    Chakraborty, S.; Resmi, A. N.; Renuka Devi, P.; Jinesh, K. B.

    2017-04-01

    Chemically reduced graphene oxide (rGO) samples with various degrees of reduction were prepared using hydrazine hydrate as the reducing agent. Scanning tunnelling microscope imaging shows that rGO contains rows of randomly distributed patches of epoxy groups. The local density of states of the rGO samples were mapped with scanning tunnelling spectroscopy, which shows that the bandgap in rGO originates from the epoxide regions itself. The Fermi level of the epoxide regions is shifted towards the valence band, making rGO locally p-type and a range of bandgaps from 0-2.2 eV was observed in these regions. Thin film transistors were fabricated using rGO as the channel layer. The devices show excellent output characteristics with clear saturation and gate dependence. The transfer characteristics show that rGO behaves as a p-type semiconductor; the devices exhibit an on/off ratio of 104, with a low-bias hole mobility of 3.9 cm2 V-1 s-1.

  20. Platinum-induced structural collapse in layered oxide polycrystalline films

    SciTech Connect

    Wang, Jianlin; Liu, Changhui; Huang, Haoliang; Fu, Zhengping; Peng, Ranran E-mail: yllu@ustc.edu.cn; Zhai, Xiaofang; Lu, Yalin E-mail: yllu@ustc.edu.cn

    2015-03-30

    Effect of a platinum bottom electrode on the SrBi{sub 5}Fe{sub 1−x}Co{sub x}Ti{sub 4}O{sub 18} layered oxide polycrystalline films was systematically studied. The doped cobalt ions react with the platinum to form a secondary phase of PtCoO{sub 2}, which has a typical Delafossite structure with a weak antiferromagnetism and an exceptionally high in-plane electrical conductivity. Formation of PtCoO{sub 2} at the interface partially consumes the cobalt dopant and leads to the structural collapsing from 5 to 4 layers, which was confirmed by X-ray diffraction and high resolution transmission electron microscopy measurements. Considering the weak magnetic contribution from PtCoO{sub 2}, the observed ferromagnetism should be intrinsic of the Aurivillius compounds. Ferroelectric properties were also indicated by the piezoresponse force microscopy. In this work, the platinum induced secondary phase at the interface was observed, which has a strong impact on Aurivillius structural configuration and thus the ferromagnetic and ferroelectric properties.

  1. Amorphous Silicon Nanowires Grown on Silicon Oxide Film by Annealing

    NASA Astrophysics Data System (ADS)

    Yuan, Zhishan; Wang, Chengyong; Chen, Ke; Ni, Zhonghua; Chen, Yunfei

    2017-08-01

    In this paper, amorphous silicon nanowires (α-SiNWs) were synthesized on (100) Si substrate with silicon oxide film by Cu catalyst-driven solid-liquid-solid mechanism (SLS) during annealing process (1080 °C for 30 min under Ar/H2 atmosphere). Micro size Cu pattern fabrication decided whether α-SiNWs can grow or not. Meanwhile, those micro size Cu patterns also controlled the position and density of wires. During the annealing process, Cu pattern reacted with SiO2 to form Cu silicide. More important, a diffusion channel was opened for Si atoms to synthesis α-SiNWs. What is more, the size of α-SiNWs was simply controlled by the annealing time. The length of wire was increased with annealing time. However, the diameter showed the opposite tendency. The room temperature resistivity of the nanowire was about 2.1 × 103 Ω·cm (84 nm diameter and 21 μm length). This simple fabrication method makes application of α-SiNWs become possible.

  2. Amorphous Silicon Nanowires Grown on Silicon Oxide Film by Annealing.

    PubMed

    Yuan, Zhishan; Wang, Chengyong; Chen, Ke; Ni, Zhonghua; Chen, Yunfei

    2017-08-10

    In this paper, amorphous silicon nanowires (α-SiNWs) were synthesized on (100) Si substrate with silicon oxide film by Cu catalyst-driven solid-liquid-solid mechanism (SLS) during annealing process (1080 °C for 30 min under Ar/H2 atmosphere). Micro size Cu pattern fabrication decided whether α-SiNWs can grow or not. Meanwhile, those micro size Cu patterns also controlled the position and density of wires. During the annealing process, Cu pattern reacted with SiO2 to form Cu silicide. More important, a diffusion channel was opened for Si atoms to synthesis α-SiNWs. What is more, the size of α-SiNWs was simply controlled by the annealing time. The length of wire was increased with annealing time. However, the diameter showed the opposite tendency. The room temperature resistivity of the nanowire was about 2.1 × 10(3) Ω·cm (84 nm diameter and 21 μm length). This simple fabrication method makes application of α-SiNWs become possible.

  3. P-channel thin film transistors using reduced graphene oxide.

    PubMed

    Chakraborty, S; Resmi, A N; Devi, P Renuka; Jinesh, K B

    2017-04-18

    Chemically reduced graphene oxide (rGO) samples with various degrees of reduction were prepared using hydrazine hydrate as the reducing agent. Scanning tunnelling microscope imaging shows that rGO contains rows of randomly distributed patches of epoxy groups. The local density of states of the rGO samples were mapped with scanning tunnelling spectroscopy, which shows that the bandgap in rGO originates from the epoxide regions itself. The Fermi level of the epoxide regions is shifted towards the valence band, making rGO locally p-type and a range of bandgaps from 0-2.2 eV was observed in these regions. Thin film transistors were fabricated using rGO as the channel layer. The devices show excellent output characteristics with clear saturation and gate dependence. The transfer characteristics show that rGO behaves as a p-type semiconductor; the devices exhibit an on/off ratio of 10(4), with a low-bias hole mobility of 3.9 cm(2) V(-1) s(-1).

  4. Growth and surface characterization of sputter-deposited molybdenum oxide thin films

    SciTech Connect

    Ramana, Chintalapalle V.; Atuchin, Victor V.; Kesler, V. G.; Kochubey, V. A.; Pokrovsky, L. D.; Shutthanandan, V.; Becker, U.; Ewing, Rodney C.

    2007-04-15

    Molybdenum oxide thin films were produced by magnetron sputtering using a molybdenum (Mo) target. The sputtering was performed in a reactive atmosphere of argon-oxygen gas mixture under varying conditions of substrate temperature (Ts) and oxygen partial pressure (pO2). The effect of Ts and pO2 on the growth and microstructure of molybdenum oxide films was examined in detail using reflection high-energy electron diffraction (RHEED), Rutherford backscattering spectrometry (RBS), energy dispersive X-ray spectrometry (EDS), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) measurements. The analyses indicate that the effect of Ts and pO2 on the microstructure and phase of the grown molybdenum oxide thin films is remarkable. RHEED and RBS results indicate that the films grown at 445 *C under 62.3% O2 pressure were stoichiometric and polycrystalline MoO3. Films grown at lower pO2 were nonstoichiometric MoOx films with the presence of secondary phase. The microstructure of the grown Mo oxide films is discussed and conditions were optimized to produce phase pure, stoichiometric, and highly textured polycrystalline MoO3 films.

  5. Electrochromic properties of nickel oxide thin films prepared by the sol-gel method

    SciTech Connect

    Miki, Takeshi; Yoshimura, Kazuki; Tai, Yutaka; Tazawa, Masato; Jin, P.; Tanemura, Sakae

    1995-12-31

    Recently electrochromic (EC) device has been attractive as a smart glazing to control heating, cooling and lighting loads of buildings and housing. Among various electrochromic materials, nickel oxide is one of the typical anode type materials. Here, the electrochromic nickel oxide films were prepared onto transparent conducting film on glass substrate by the sol-gel method using an ethylene glycol solution of nickel nitrate hexahydrate. The films produced by the dip-coating method and calcined at 250, 300 and 350 C. The formed films were characterized by their electrochromic behavior in cyclic voltammetry. The formed films showed electrochromic behavior in 1M KOH aqueous solution as electrolytic solution. The cyclic voltammograms were recorded up to 100 cycles for each film. The anodic peak of the coloration reaction appeared at approximately +400 mV, while the cathodic peak of the bleaching reaction occurred at about +200 mV vs. Ag/AgCl. Both the anodic peak and the cathodic peak increased with an increase of the cyclic numbers in voltammograms, whereas these peaks at 100 cycles decreased with an increase of the calcination temperature of nickel oxide films. The calcination gave great influence on the other electrochromic behaviors of nickel oxide films.

  6. Antibody-Modified Reduced Graphene Oxide Films with Extreme Sensitivity to Circulating Tumor Cells.

    PubMed

    Li, Yingying; Lu, Qihang; Liu, Hongliang; Wang, Jianfeng; Zhang, Pengchao; Liang, Huageng; Jiang, Lei; Wang, Shutao

    2015-11-18

    An antibody-modified reduced graphene oxide (rGO) film with unexpected -extreme sensitivity to circulating tumor cells (CTCs) is reported. The antibody--modified rGO films efficiently capture CTCs from billions of blood cells and minimize the background of white blood cells, without complex microfluidic operations.

  7. Simple Methods for Production of Nanoscale Metal Oxide Films from Household Sources

    ERIC Educational Resources Information Center

    Campbell, Dean J.; Baliss, Michelle S.; Hinman, Jordan J.; Ziegenhorn, John W.; Andrews, Mark J.; Stevenson, Keith J.

    2013-01-01

    Production of thin metal oxide films was recently explored as part of an outreach program with a goal of producing nanoscale structures with household items. Household items coated with various metals or titanium compounds can be heated to produce colorful films with nanoscale thicknesses. As part of a materials chemistry laboratory experiment…

  8. Amorphous vanadium oxide films synthesised by ALCVD for lithium rechargeable batteries

    NASA Astrophysics Data System (ADS)

    Le Van, K.; Groult, H.; Mantoux, A.; Perrigaud, L.; Lantelme, F.; Lindström, R.; Badour-Hadjean, R.; Zanna, S.; Lincot, D.

    This study addresses the lithium insertion performances of amorphous vanadium oxide films, synthesized by atomic layer chemical vapour deposition (ALCVD). AFM and SEM investigations showed that the as-deposited films are amorphous, compact and homogeneous. As revealed by XPS and Raman spectroscopy, the ALCVD oxide films after deposition are mainly composed of V 2O 5, with V 4+ surface content (about 10%). The insertion of Li + into the lattice was investigated in 1 M LiClO 4-PC. The results show that the electrochemical performances obtained with amorphous vanadium oxide films, with an optimal thickness of 200 nm (455 mAh g -1, i.e. composition of Li 2.9V 2O 5), were superior to crystalline V 2O 5 films. The amorphous films exhibit higher capacity and better cycle ability even for deep lithium insertion ratio compared to crystalline V 2O 5 films. The chemical diffusion coefficients, deduced from numerical simulation of chronopotentiograms, were comprised between 3 × 10 -12 and 10 -13 cm 2 s -1 for a lithium insertion ratio comprised between 0 and 2.9. AFM and Raman spectroscopy performed before and after lithiation showed that neither the morphology nor the local order of the amorphous films were significantly affected by the insertion/extraction of lithium. Raman measurements also revealed that a very small amount of lithium are locally trapped in the oxide lattice.

  9. Simple Methods for Production of Nanoscale Metal Oxide Films from Household Sources

    ERIC Educational Resources Information Center

    Campbell, Dean J.; Baliss, Michelle S.; Hinman, Jordan J.; Ziegenhorn, John W.; Andrews, Mark J.; Stevenson, Keith J.

    2013-01-01

    Production of thin metal oxide films was recently explored as part of an outreach program with a goal of producing nanoscale structures with household items. Household items coated with various metals or titanium compounds can be heated to produce colorful films with nanoscale thicknesses. As part of a materials chemistry laboratory experiment…

  10. Atomic Layer-Deposited Titanium-Doped Vanadium Oxide Thin Films and Their Thermistor Applications

    NASA Astrophysics Data System (ADS)

    Wang, Shuyu; Yu, Shifeng; Lu, Ming; Liu, Mingzhao; Zuo, Lei

    2017-04-01

    Here we report the enhancement in the temperature coefficient of resistance (TCR) of atomic layer-deposited vanadium oxide thin films through the doping of titanium oxide. The Hall effect measurement provides a potential explanation for the phenomenon. The composition and morphology of the thin films are investigated by x-ray diffraction and scanning electron microscopy techniques. The high TCR, good uniformity, and low processing temperature of the material make it a good candidate for thermistor application.

  11. Estimation of the composition parameter of electrochemically colored amorphous hydrogen tungsten oxide films

    NASA Astrophysics Data System (ADS)

    Kaneko, Hiroko; Miyake, Kiyoshi

    1989-07-01

    The electrical and optical steady state observed in electrochemical coloration has been studied using asymmetric cells consisting of evaporated amorphous tungsten oxide films with 350-6000 Å thickness. The counter electrode used is indium wire, steel wire, or antimony-tin oxide film, and the electrolyte is a 1-N H2SO4 aqueous solution containing 10 vol % glycerol. The current and optical transmittance of the cells decrease with increasing time during coloration, and simultaneously reach a steady state. The optical density (λ=0.5 μm) in the steady state is proportional to the thickness of the tungsten oxide film, and the absorption coefficient at λ=0.5 μm of the colored oxide film in the state is approximately 9.0×104 cm-1. The effective charges which contribute to the coloration of films calculated from the charge injected until the electro-optical steady state were found to be 1.03-1.20×103 C/cm3. Assuming that the evaporated tungsten oxide films used have a distorted ReO3 structure, and that a hydrogen tungsten bronze HxWO3 is formed by coloration, the composition parameter x calculated from the average value of the effective charge, is 0.36, which is comparable with that of hydrogen tungsten bronze H0.33WO3 obtained for the colored crystalline WO3 films.

  12. Generation of metal, metal oxide and metal-metal oxide powders by spray pyrolysis for microelectronic thick film applications

    NASA Astrophysics Data System (ADS)

    Majumdar, Diptarka

    Materials in powdered form have wide ranging applications. In thick film microelectronics, powders are dispersed in organic liquids to form pastes which are screen printed on ceramic substrates and fired to fabricate active and passive electronic devices. The functional phase is a metal powder in conductive pastes, a metal or conductive metal oxide powder in resistive pastes and a ceramic powder in dielectric pastes. Particulate additives such as glasses and metal oxides in pastes promote adhesion of conductor lines to the substrate, minimize shrinkage mismatch during cofiring of conductors and dielectrics and facilitate densification of the functional phase during firing. This dissertation focuses on the generation of metal, metal oxide and metal-metal oxide powders by spray pyrolysis for microelectronic applications. The important results of this work are outlined below. (1) This work has demonstrated the ability to synthesize phase-pure, micron-sized, spherical, unagglomerated metal (gold) and metal oxide (copper (I) oxide) particles by spray pyrolysis. (2) It has extended the versatility of spray pyrolysis as a powdermaking technique to include the synthesis of metal-metal oxide composite particles. Such particles have been generated for both wetting (silver-copper (II) oxide) and poorly wetting (silver-silica) metal-metal oxide pairs. (3) The sintering of thick films of the metal-metal oxide particles has indicated the possibility of retarding the sintering kinetics of silver by using composite particles of the metal with relatively refractory metal oxides.

  13. Characterization of quaternary metal oxide films by synchrotron x-ray fluorescence microprobe

    SciTech Connect

    Perry, D.L.; Thompson, A.C.; Russo, R.E.

    1997-04-01

    A high demand for thin films in industrial technology has been responsible for the creation of new techniques for the fabrication of such films. One highly effective method for the syntheses of variable composition thin films is pulsed-laser deposition (PLD). The technique has a large number of characteristics which make it an attractive approach for making films. It offers rapid deposition rates, congruent material transfer, simple target requirements from which to make the films, in situ multilayer deposition, and no gas composition or pressure requirements. Additionally, the technique can also afford crystalline films and films with novel structures. Pulsed-laser deposition can be used to make films of semiconductors, insulators, high-temperature superconductors, diamond-like films, and piezoelectric materials. Quaternary metal oxides involving calcium, nickel, and potassium have been shown to be quite effective in the catalysis of coal gasification and methane coupling. One approach to incorporating all three of the metal oxides into one phase is the use of laser ablation to prepare films of the catalysts so that they may be used for coatings, smooth surfaces on which to conduct detailed studies of gas-solid interface reactions that are involved in catalytic processes, and other applications. The problem of dissimilar boiling points of the three metal oxides system is overcome, since the laser ablation process effects the volatilization of all three components from the laser target essentially simultaneously. There is strong interest in gaining an understanding of the chemical and morphological aspects of the films that are deposited. Phenomena such as lattice defects and chemical heterogeneity are of interest. The experimental data discussed here are restricted to the matrix homogeneity of the films themselves for films which were void of microparticles.

  14. Epitaxial growth and structure of monolayer cerium oxide films on Rh(111)

    NASA Astrophysics Data System (ADS)

    Chan, Lap Hong; Yuhara, Junji

    2017-07-01

    We prepared monolayer cerium (Ce) oxide films on Rh(111) to investigate their growth and structure using scanning tunneling microscopy (STM), low-energy electron diffraction, X-ray photoemission spectroscopy (XPS), and density functional theory (DFT) calculations. For quantitative analysis of Ce-oxide films, we used the combined techniques of XPS and Rutherford backscattering spectrometry to determine the concentration of Ce and O atoms. We prepared a monolayer (ML) Ce-oxide film by annealing a metallic Ce film at 0.3 ML coverage in an oxygen atmosphere. A well-ordered Ce-oxide phase with a (4×4) unit cell was obtained. The epitaxially grown Ce-oxide film aligned along the <110> azimuthal direction of Rh(111). The number of Ce and O atoms in the (4×4) unit cell was estimated. The STM images indicated that the two-dimensional island growth of the p(4×4) phase with p3m1 symmetry can be explained using the missing Ce atoms model. A simulated STM image of the p(4×4) structural model was in good agreement with the experimental STM image. The formation of Ce-oxide films on Rh(111) at submonolayer coverage was discussed on the basis of the results of DFT+U calculations.

  15. Thin film bismuth iron oxides useful for piezoelectric devices

    DOEpatents

    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.

  16. Preparation of Grayish Black Film on AM50 Magnesium Alloy by Chemical Conversion-Micro Oxidation

    NASA Astrophysics Data System (ADS)

    Shao, Zhongcai; Zhang, Feifei; Zhang, Qingfang; Yang, Li; Shen, Xiaoyi

    2017-07-01

    The grayish black film was prepared on AM50 magnesium alloy with a new method which combined chemical conversion with micro-arc oxidation (MAO). The optimum formula of chemical conversion was obtained by L9(34) orthogonal test. Meanwhile, the morphology, structure, composition and corrosion resistance of films were analyzed by scanning electron microscopy (SEM), energy spectrum analysis (energy dispersive X-ray spectroscopy (EDS)), X-ray diffraction (XRD), electrochemical tests and CuSO4 drip experiment. The results indicated that Mo element was introduced into the MAO film by chemical conversion pretreatment. The surface of composite film was smooth and compact. The main phase composition of the composite film were SiO2, Mo9O26, MgSiO3, Mg2SiO4 and Mo9O26 was identified to be responsible for giving color to the film. The corrosion resistance of the grayish black film was improved obviously.

  17. Properties of electrochromic nickel-vanadium oxide films sputter-deposited from nonmagnetic alloy target

    NASA Astrophysics Data System (ADS)

    Avendano, Esteban; Azens, Andris; Niklasson, Gunnar A.

    2001-11-01

    In this study we investigate the structure, composition, diffusion coefficient, and electrochromic properties of nickel-vanadium oxide films as a function of deposition conditions. Polycrystalline films have been deposited by DC magnetron sputtering from a nonmagnetic target of Ni0.93V0.07 in an atmosphere of O2/Ar and Ar/O2/H2, with the gas flow ratios varied systematically to cover the range from nearly-metallic to overoxidized films. The results contradict the usual view that films deposited in O2/Ar are dark brown in their as-deposited state. While such films can easily be deposited, the optimum electrochromic properties have been observed at O2/Ar ratios giving nearly transparent films. Addition of hydrogen to the sputtering atmosphere improved cycling stability of the films. The diffusion coefficient has been determined by the Galvanostatic Intermittent Titration Technique (GITT).

  18. Nucleation and growth of tetracene films on silicon oxide

    SciTech Connect

    Shi, J.; Qin, X. R.

    2008-09-15

    Tetracene film growth on SiO{sub 2} at room temperature via vacuum evaporation has been studied using ex situ atomic force microscopy. We demonstrate that tetracene films of layered morphology and good connectivity can be achieved on SiO{sub 2} under favorable growth conditions. Island size distribution analysis shows that tetracene nucleation in the optimal growth is diffusion mediated with a smallest stable cluster consisting of four molecules (i.e., the critical island size i=3). The film stability is sensitive to the film thickness. Postgrowth film structural evolution occurs on the time scale of minutes for the films at coverage less than three monolayers, while stable films become evident at coverage higher than three monolayers.

  19. Process for growing a film epitaxially upon an oxide surface and structures formed with the process

    DOEpatents

    McKee, Rodney Allen; Walker, Frederick Joseph

    1998-01-01

    A process and structure wherein a film comprised of a perovskite or a spinel is built epitaxially upon a surface, such as an alkaline earth oxide surface, involves the epitaxial build up of alternating constituent metal oxide planes of the perovskite or spinel. The first layer of metal oxide built upon the surface includes a metal element which provides a small cation in the crystalline structure of the perovskite or spinel, and the second layer of metal oxide built upon the surface includes a metal element which provides a large cation in the crystalline structure of the perovskite or spinel. The layering sequence involved in the film build up reduces problems which would otherwise result from the interfacial electrostatics at the first atomic layers, and these oxides can be stabilized as commensurate thin films at a unit cell thickness or grown with high crystal quality to thicknesses of 0.5-0.7 .mu.m for optical device applications.

  20. Process for growing a film epitaxially upon an oxide surface and structures formed with the process

    DOEpatents

    McKee, Rodney A.; Walker, Frederick J.

    1995-01-01

    A process and structure wherein a film comprised of a perovskite or a spinel is built epitaxially upon a surface, such as an alkaline earth oxide surface, involves the epitaxial build up of alternating constituent metal oxide planes of the perovskite or spinel. The first layer of metal oxide built upon the surface includes a metal element which provides a small cation in the crystalline structure of the perovskite or spinel, and the second layer of metal oxide built upon the surface includes a metal element which provides a large cation in the crystalline structure of the perovskite or spinel. The layering sequence involved in the film build up reduces problems which would otherwise result from the interfacial electrostatics at the first atomic layers, and these oxides can be stabilized as commensurate thin films at a unit cell thickness or grown with high crystal quality to thicknesses of 0.5-0.7 .mu.m for optical device applications.

  1. Effects of PbO on the oxide films of incoloy 800HT in simulated primary circuit of PWR

    NASA Astrophysics Data System (ADS)

    Tan, Yu; Yang, Junhan; Wang, Wanwan; Shi, Rongxue; Liang, Kexin; Zhang, Shenghan

    2016-05-01

    Effects of trace PbO on oxide films of Incoloy 800HT were investigated in simulated primary circuit water chemistry of PWR, also with proper Co addition. The trace PbO addition in high temperature water blocked the protective spinel oxides formation of the oxide films of Incoloy 800HT. XPS results indicated that the lead, added as PbO into the high temperature water, shows not only +2 valance but also +4 and 0 valances in the oxide film of 800HT co-operated with Fe, Cr and Ni to form oxides films. Potentiodynamic polarization results indicated that as PbO concentration increased, the current densities of the less protective oxide films of Incoloy 800HT decreased in a buffer solution tested at room temperature. The capacitance results indicated that the donor densities of oxidation film of Incoloy 800HT decreased as trace PbO addition into the high temperature water.

  2. Investigation on vanadium oxide thin films deposited by spray pyrolysis technique

    NASA Astrophysics Data System (ADS)

    Margoni, Mudaliar Mahesh; Mathuri, S.; Ramamurthi, K.; Babu, R. Ramesh; Sethuraman, K.

    2016-05-01

    Vanadium oxide thin films were deposited at 400 °C by spray pyrolysis technique using 0.1 M aqueous precursor solution of ammonium meta vanadate (AMV) with two different pH values. X-ray diffraction results showed that the film prepared using aqueous precursor AMV solution (solution A; pH 7) is amorphous in nature and the film prepared by adding HNO3 in the AMV aqua solution A (solution B; pH 3) is polycrystalline in nature. Vanadium oxide film prepared from the precursor solution B is in the mixed phases of V2O5 and V4O7. Crystallinity is improved for the film prepared using solution B when compared to film prepared from solution A. Crystallite size, strain and dislocation density calculated for the film prepared from solution B is respectively 72.1 nm, 0.4554 × 10-3 lin.-2m-4 and 1.7263 × 1014 lin.m-2. Morphology study revealed that the size of the flakes formed on the surface of the films is influenced by the pH of the precursor solution. Average Visible Transmittance and maximum transmittance of the deposited films exceed 70% and the direct optical band gap value calculated for the films deposited from A and B solution is 1.91 eV and 2.08 eV respectively.

  3. Effects of working pressure on physical properties of tungsten-oxide thin films sputtered from oxide target

    SciTech Connect

    Riech, I.; Acosta, M.; Pena, J. L.; Bartolo-Perez, P.

    2010-03-15

    Tungsten-oxide films were deposited on glass substrates from a metal-oxide target by nonreactive radio-frequency sputtering. The authors have studied the effect that changing Ar gas pressure has on the electrical, optical, and chemical composition in the thin films. Resistivity of WO{sub 3} changed ten orders of magnitude with working gas pressure values from 20 to 80 mTorr. Thin films deposited at 20 mTorr of Ar sputtering pressure showed lower resistivity and optical transmittance. X-ray photoelectron spectroscopy (XPS) measurements revealed similar chemical composition for all samples irrespective of Ar pressure used. However, XPS analyses of the evolution of W 4f and O 1s peaks indicated a mixture of oxides dependent on the Ar pressure used during deposition.

  4. Glucose-assisted reduction achieved transparent p-type cuprous oxide thin film by a solution method

    NASA Astrophysics Data System (ADS)

    Nie, Sha; Sun, Jian; Gong, Hao; Chen, Zequn; Huang, Yifei; Xu, Jianmei; Zhao, Ling; Zhou, Wei; Wang, Qing

    2016-08-01

    The fabrication of p-type cuprous oxide thin film via a cheap and simple chemical method has been known as challenging. We first find that glucose can assist reduce Cu to a lower valence state in the preparation of cuprous oxide films by the sol-gel method. By first adding glucose in the sol as reducing agent, oxidation from the oxygen in the environment is limited and transparent p-type cuprous oxide films are eventually achieved under optimized experimental conditions. We have developed a p-type cuprous oxide thin film with an optimal Hall mobility of ∼8 cm2/Vs and an optical transmittance of 78%.

  5. Characterization of ultrathin silicon oxide films with mirror-enhanced polarized reflectance Fourier transform infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Cui, Zhenjiang; Takoudis, Christos G.

    2001-05-01

    Ultrathin silicon oxide films thermally grown on Si (100) are characterized with mirror-enhanced polarized reflectance Fourier transform infrared spectroscopy (MEPR-FTIR). MEPR-FTIR is proposed to effectively probe properties of ultrathin films. Using a mirror and a polarizer, MEPR-FTIR overcomes the difficulty of weak IR intensities normally encountered in ultrathin gate dielectrics such as SiO2; the intensity of the silicon oxide longitudinal optical (LO) mode is found to increase by a factor of about 20. Therefore, FTIR spectrometers with sensitivity down to 0.01% may allow even submonolayer probing of silicon oxide on Si substrates. The relationship between film thickness and IR intensity of the LO mode at 1252 cm-1 is presented for silicon oxide films as thin as a few Å thick. Independent measurements with ellipsometry, cross-sectional transmission electron microscopy, and x-ray photoelectron spectroscopy as well as theoretical predictions using the general Fresnel function are utilized. Although nonlinear overall, the theoretically predicted relationship between the MEPR-FTIR intensity and film thickness is almost linear within the range 0-50 Å. Experimental data are shown to agree very well with the theoretical calculations for two different kinds of oxides: thermal oxides grown at 1050 °C and native oxides. Such results suggest that the MEPR-FTIR can be useful as an ex situ or in situ technique for thickness measurements and, in fact, for other properties of ultrathin gate dielectrics.

  6. Nano-oxide thin films deposited via atomic layer deposition on microchannel plates.

    PubMed

    Yan, Baojun; Liu, Shulin; Heng, Yuekun

    2015-01-01

    Microchannel plate (MCP) as a key part is a kind of electron multiplied device applied in many scientific fields. Oxide thin films such as zinc oxide doped with aluminum oxide (ZnO:Al2O3) as conductive layer and pure aluminum oxide (Al2O3) as secondary electron emission (SEE) layer were prepared in the pores of MCP via atomic layer deposition (ALD) which is a method that can precisely control thin film thickness on a substrate with a high aspect ratio structure. In this paper, nano-oxide thin films ZnO:Al2O3 and Al2O3 were prepared onto varied kinds of substrates by ALD technique, and the morphology, element distribution, structure, and surface chemical states of samples were systematically investigated by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoemission spectroscopy (XPS), respectively. Finally, electrical properties of an MCP device as a function of nano-oxide thin film thickness were firstly studied, and the electrical measurement results showed that the average gain of MCP was greater than 2,000 at DC 800 V with nano-oxide thin film thickness approximately 122 nm. During electrical measurement, current jitter was observed, and possible reasons were preliminarily proposed to explain the observed experimental phenomenon.

  7. Advanced functional oxide thin films grown by pulsed-laser deposition

    NASA Astrophysics Data System (ADS)

    Millon, E.

    2013-08-01

    Pulsed-laser deposition is now a largely used growth method to prepare functional and multifunctional oxide films for application in microelectronics, spintronics, optics, materials for energy… The functional properties of such oxide films are strongly depending on the crystalline structure, and on the chemical composition through the local environment of cationic species surrounded by oxygen. While large oxygen deficiency cannot be obtained by classical growth method or in bulk state, oxide films with a high content of oxygen vacancies may be obtained by PLD. For oxide systems presenting possible stable sub-oxides, the formation of oxygen vacancies is linked to a decrease of the cationic valence state. A complete reduction can be observed leading to particular electronic properties: the case of TiOx (1.5 < x < 2) will be therefore presented and discussed. When no thermodynamically stable sub-oxides can be involved, the large oxygen deficiency may lead to the formation of nanocomposite films constituted by a metallic phase embedded in a stoichiometric oxide matrix. This phase separation induced by the control of oxygen pressure during the growth is in particular evidenced on Ga2Ox (2.1 < x < 3) films and their related physical (electrical and optical) properties are discussed.

  8. Preparation of Thin Melanin-Type Films by Surface-Controlled Oxidation.

    PubMed

    Salomäki, Mikko; Tupala, Matti; Parviainen, Timo; Leiro, Jarkko; Karonen, Maarit; Lukkari, Jukka

    2016-04-26

    The preparation of thin melanin films suitable for applications is challenging. In this work, we present a new alternative approach to thin melanin-type films using oxidative multilayers prepared by the sequential layer-by-layer deposition of cerium(IV) and inorganic polyphosphate. The interfacial reaction between cerium(IV) in the multilayer and 5,6-dihydroxyindole (DHI) in the adjacent aqueous solution leads to the formation of a thin uniform film. The oxidation of DHI by cerium(IV) proceeds via known melanin intermediates. We have characterized the formed DHI-melanin films using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), UV-vis spectroscopy, and spectroelectrochemistry. When a five-bilayer oxidative multilayer is used, the film is uniform with a thickness of ca. 10 nm. Its chemical composition, as determined using XPS, is typical for melanin. It is also redox active, and its oxidation occurs in two steps, which can be assigned to semiquinone and quinone formation within the indole structural motif. Oxidative multilayers can also oxidize dopamine, but the reaction stops at the dopamine quinone stage because of the limited amount of the multilayer-based oxidizing agent. However, dopamine oxidation by Ce(IV) was studied also in solution by UV-vis spectroscopy and mass spectrometry in order to verify the reaction mechanism and the final product. In solution, the oxidation of dopamine by cerium shows that the indole ring formation takes place already at low pH and that the mass spectrum of the final product is practically identical with that of commercial melanin. Therefore, layer-by-layer formed oxidative multilayers can be used to deposit functional melanin-type thin films on arbitrary substrates by a surface-controlled reaction.

  9. An alternative route towards micro- and nano-patterning of oxide films.

    PubMed

    Bridoux, G; Barzola-Quiquia, J; Bern, F; Böhlmann, W; Vrejoiu, I; Ziese, M; Esquinazi, P

    2012-03-02

    This paper presents a method to obtain submicron- and nanometer structures of different oxide films and heterostructures combining e-beam lithography and chemical etching. The most relevant advantage of this method is that structures of tens of microns in length and below ∼100 nm width can be produced, keeping the intrinsic bulk film properties, as proven by electrical transport measurements. In this way our method provides a bridge that connects the attractive properties of oxide films and the nanoworld.

  10. Solid-phase electrochemical reduction of graphene oxide films in alkaline solution.

    PubMed

    Basirun, Wan J; Sookhakian, Mehran; Baradaran, Saeid; Mahmoudian, Mohammad R; Ebadi, Mehdi

    2013-09-24

    Graphene oxide (GO) film was evaporated onto graphite and used as an electrode to produce electrochemically reduced graphene oxide (ERGO) films by electrochemical reduction in 6 M KOH solution through voltammetric cycling. Fourier transformed infrared and Raman spectroscopy confirmed the presence of ERGO. Electrochemical impedance spectroscopy characterization of ERGO and GO films in ferrocyanide/ferricyanide redox couple with 0.1 M KCl supporting electrolyte gave results that are in accordance with previous reports. Based on the EIS results, ERGO shows higher capacitance and lower charge transfer resistance compared to GO.

  11. Solid-phase electrochemical reduction of graphene oxide films in alkaline solution

    PubMed Central

    2013-01-01

    Graphene oxide (GO) film was evaporated onto graphite and used as an electrode to produce electrochemically reduced graphene oxide (ERGO) films by electrochemical reduction in 6 M KOH solution through voltammetric cycling. Fourier transformed infrared and Raman spectroscopy confirmed the presence of ERGO. Electrochemical impedance spectroscopy characterization of ERGO and GO films in ferrocyanide/ferricyanide redox couple with 0.1 M KCl supporting electrolyte gave results that are in accordance with previous reports. Based on the EIS results, ERGO shows higher capacitance and lower charge transfer resistance compared to GO. PMID:24059434

  12. Solid-phase electrochemical reduction of graphene oxide films in alkaline solution

    NASA Astrophysics Data System (ADS)

    Basirun, Wan J.; Sookhakian, Mehran; Baradaran, Saeid; Mahmoudian, Mohammad R.; Ebadi, Mehdi

    2013-09-01

    Graphene oxide (GO) film was evaporated onto graphite and used as an electrode to produce electrochemically reduced graphene oxide (ERGO) films by electrochemical reduction in 6 M KOH solution through voltammetric cycling. Fourier transformed infrared and Raman spectroscopy confirmed the presence of ERGO. Electrochemical impedance spectroscopy characterization of ERGO and GO films in ferrocyanide/ferricyanide redox couple with 0.1 M KCl supporting electrolyte gave results that are in accordance with previous reports. Based on the EIS results, ERGO shows higher capacitance and lower charge transfer resistance compared to GO.

  13. Cathodic arc sputtering of functional titanium oxide thin films, demonstrating resistive switching

    NASA Astrophysics Data System (ADS)

    Shvets, Petr; Maksimova, Ksenia; Demin, Maxim; Dikaya, Olga; Goikhman, Alexander

    2017-05-01

    The formation of thin films of the different stable and metastable titanium oxide phases is demonstrated by cathode arc sputtering of a titanium target in an oxygen atmosphere. We also show that sputtering of titanium in vacuum yields the formation of titanium silicides on the silicon substrate. The crystal structure of the produced samples was investigated using Raman spectroscopy and X-ray diffraction. We conclude that cathode arc sputtering is a flexible method suitable for producing the functional films for electronic applications. The functionality is verified by the memory effect demonstration, based on the resistive switching in the titanium oxide thin film structure.

  14. Different properties of aluminum doped zinc oxide nanostructured thin films prepared by radio frequency magnetron sputtering

    SciTech Connect

    Bidmeshkipour, Samina Shahtahmasebi, Nasser

    2013-06-15

    Aluminium doped zinc oxide (AZO) nanostructured thin films are prepared by radio frequency magnetron sputtering on glass substrate using specifically designed ZnO target containing different amount of Al{sub 2}O{sub 3} powder as the Al doping source. The optical properties of the aluminium doped zinc oxide films are investigated. The topography of the deposited films were investigated by Atomic Force Microscopy. Variation of the refractive index by annealing temperature are considered and it is seen that the refractive index increases by increasing the annealing temperature.

  15. X-ray absorption spectroscopy studies of electrochemically deposited thin oxide films.

    SciTech Connect

    Balasubramanian, M.

    1998-06-02

    We have utilized ''in situ'' X-ray Absorption Fine Structure Spectroscopy to investigate the structure and composition of thin oxide films of nickel and iron that have been prepared by electrodeposition on a graphite substrate from aqueous solutions. The films are generally disordered. Structural information has been obtained from the analysis of the data. We also present initial findings on the local structure of heavy metal ions, e.g. Sr and Ce, incorporated into the electrodeposited nickel oxide films. Our results are of importance in a number of technological applications, among them, batteries, fuel cells, electrochromic and ferroelectric materials, corrosion protection, as well as environmental speciation and remediation.

  16. Erbium oxide thin films on Si(100) obtained by laser ablation and electron beam evaporation

    NASA Astrophysics Data System (ADS)

    Queralt, X.; Ferrater, C.; Sánchez, F.; Aguiar, R.; Palau, J.; Varela, M.

    1995-02-01

    Erbium oxide thin films have been obtained by laser ablation and electron beam evaporation techniques on Si(100) substrates. The samples were grown under different conditions of oxygen atmosphere and substrate temperature without any oxidation process after deposition. The crystal structure has been studied by X-ray diffraction. Films obtained by laser ablation are highly textured in the [ hhh] direction, although this depends on the conditions of oxygen pressure and substrate temperature. In order to study the depth composition profile of the thin films and the interdiffusion of erbium metal and oxygen towards the silicon substrates, X-ray photoelectron spectroscopy analyses have been carried out.

  17. Electronic and transport properties of reduced and oxidized nanocrystalline TiO2 films

    NASA Astrophysics Data System (ADS)

    Rothschild, A.; Komem, Y.; Levakov, A.; Ashkenasy, N.; Shapira, Yoram

    2003-01-01

    Electronic properties of reduced (vacuum-annealed) and oxidized (air-annealed) TiO2 films were investigated by in situ conductivity and current-voltage measurements as a function of the ambient oxygen pressure and temperature, and by ex situ surface photovoltage spectroscopy. The films were quite conductive in the reduced state but their resistance drastically increased upon exposure to air at 350 °C. In addition, the surface potential barrier was found to be much larger for the oxidized versus the reduced films. This behavior may be attributed to the formation of surface and grain boundary barriers due to electron trapping at interface states associated with chemisorbed oxygen species.

  18. Metal oxidation kinetics and the transition from thin to thick films.

    PubMed

    Xu, Zhijie; Rosso, Kevin M; Bruemmer, Stephen

    2012-11-14

    We report an investigation of growth kinetics and transition from thin to thick films during metal oxidation. In the thin film limit (<20 nm), Cabrera and Mott's theory is usually adopted by explicitly considering ionic drift through the oxide in response to electric fields, where the growth kinetics follow an inverse logarithmic law log(dl/dt) is proportional to 1/l. It is generally accepted that Wagner's theory, involving self-diffusion, is valid only in the limit of thick film regime (>1 μm) and leads to parabolic growth kinetics dl/dt is proportional to 1/l, where l is the oxide film thickness. Theory presented here unifies the two models and provides a complete description of oxidation including the transition from thin to thick film. The range of validity of Cabrera and Mott's theory and Wagner's theory can be well defined in terms of the Debye-Hückel screening length. The transition from drift-dominated ionic transport for thin film to diffusion-dominated transport for thick film is found to strictly follow the direct logarithmic law log(dl/dt) is proportional to -l that is frequently observed in many experiments.

  19. Metal Oxidation Kinetics and the Transition from Thin to Thick Films

    SciTech Connect

    Xu, Zhijie; Rosso, Kevin M.; Bruemmer, Stephen M.

    2012-09-01

    We report an investigation of growth kinetics and transition from thin to thick films during metal oxidation. In the thin film limit (< 20 nm), Cabrera and Mott’s theory is usually adopted by explicitly considering ionic drift through the oxide in response to electric fields, where the growth kinetics follow an inverse logarithmic law . It is generally accepted that Wagner’s theory, involving self-diffusion, is valid only in the limit of thick film regime (>1μm) and leads to parabolic growth kinetics , where l is the oxide film thickness. Theory presented here unifies the two models and provides a complete description of oxidation including the transition from thin to thick film. The range of validity of Cabrera and Mott’s theory and Wagner’s theory can be well defined in terms of the Debye-Hückel screening length. The transition from drift-dominated ionic transport for thin film to diffusion-dominated transport for thick film is found to strictly follow the direct logarithmic law that is frequently observed in many experiments.

  20. Deposition of oxide thin films on silicon using organic self-assembled monolayers

    NASA Astrophysics Data System (ADS)

    DeGuire, Mark R.; Shin, Hyunjung; Collins, R. J.; Agarwal, Monika; Sukenik, Chaim N.; Heuer, Arthur H.

    1996-03-01

    Crystalline oxide thin films have been synthesized at low temperatures from aqueous liquid solutions. A key element of the approach is the use of organic self-assembled monolayers (SAMs) on the substrate to promote the growth of adherent inorganic films. A SAM is a close- packed, highly ordered array of long-chain hydrocarbon molecules, anchored to the substrate by covalent bonds. The terminating functional group on the SAM surface is chosen so as to initiate and help sustain the formation of the oxide film when the substrate is immersed in the oxide precursor solution. Synthesis, microstructural characterization, and properties of TiO2, ZrO2, SiO2, and Y2O3 films are surveyed. Crystalline films were formed either directly from solution, or through subsequent heat treatments at temperatures that in most cases were lower than typical sol-gel or vapor phase deposition processes. All depositions were from aqueous solutions onto single-crystal (100) silicon. The ability to produce patterned films on a micron scale has been demonstrated, taking advantage of the selective deposition characteristics towards different surface functional groups of the SAM. The role of the SAM in oxide film formation is discussed.

  1. Structural and optical properties of zinc oxide film using RF-sputtering technique

    SciTech Connect

    Hashim, A. J.; Jaafar, M. S.; Ghazai, Alaa J.

    2012-11-27

    This paper reports the fabrication of zinc oxide (ZnO) film using RF-sputtering technique. Determination of the structural properties using High Resolution X-ray Diffraction (HRXRD) confirmed that ZnO film deposited on silicon (Si) substrate has a high quality. This result is in line with the Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) which were used to image the morphology of the film, in which a rough surface was demonstrated. Photoluminescence (PL) emission is included to study the optical properties of ZnO film that shows two PL peak in the UV region at 371 nm and in visible region at 530 nm respectively.

  2. Optical and electrical characterizations of nanocomposite film of titania adsorbed onto oxidized multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Feng, Wei; Feng, Yiyu; Wu, Zigang; Fujii, Akihiko; Ozaki, Masanori; Yoshino, Katsumi

    2005-07-01

    Composite film containing titania electrostatically linked to oxidized multiwalled carbon nanotubes (TiO2-s-MWNTs) was prepared from a suspension of TiO2 nanoparticles in soluble carbon nanotubes. The structure of the film was analysed principally by Fourier transform infrared spectroscopy, scanning electron micrography and x-ray diffraction. The optical and electrical characterizations of the film were investigated by UV-vis spectrum, photoluminescence and photoconductivity. The enhancement of photocurrent in the TiO2-s-MWNT film is discussed by taking the photoinduced charge transfer between the MWNT and TiO2 into consideration.

  3. Study on mixed vanadium oxide thin film deposited by RF magnetron sputtering and its application

    NASA Astrophysics Data System (ADS)

    Ling, Zhang; Jianhui, Tu; Hao, Feng; Jingzhong, Cui

    Vanadium oxide (VOx) thin films were deposited on fused quartz using a pure metal vanadium target by RF reactive magnetron sputtering technique. Film microstructure, valence state, optical transmittance properties were studied. The mixed valence VOx thin films deposited with different thickness were found to be amorphous. And the optical transmittance curves are flatness in certain wavelength region. These films can be used to control the relative light intensity of the rubidium light beam between the rubidium lamp and the vapor cell, in order to optimize the working parameters of the rubidium frequency standard (RAFS).

  4. Highly Sensitive and Fast Response Colorimetric Humidity Sensors Based on Graphene Oxides Film.

    PubMed

    Chi, Hong; Liu, Yan Jun; Wang, FuKe; He, Chaobin

    2015-09-16

    Uniform graphene oxide (GO) film for optical humidity sensing was fabricated by dip-coating technique. The resulting GO thin film shows linear optical shifts in the visible range with increase of humidity in the whole relative humidity range (from dry state to 98%). Moreover, GO films exhibit ultrafast sensing to moisture within 250 ms because of the unique atomic thinness and superpermeability of GO sheets. The humidity sensing mechanism was investigated using XRD and computer simulation. The ultrasensitive humidity colorimetric properties of GOs film may enable many potential applications such as disposable humidity sensors for packaging, health, and environmental monitoring.

  5. Synthesis of iridescent Ni-containing anodic aluminum oxide films by anodization in oxalic acid

    NASA Astrophysics Data System (ADS)

    Xu, Qin; Ma, Hong-Mei; Zhang, Yan-Jun; Li, Ru-Song; Sun, Hui-Yuan

    2016-02-01

    Ni-containing anodic aluminum oxide films with highly saturated colors were synthesized using an ac electrodeposition method, and the optical and magnetic characteristics of the films were characterized. Precisely controllable color tuning could be obtained using wet-chemical etching to thin and widen the anodic aluminum oxide films pores isotropically before Ni deposition. Magnetic measurements indicate that such colored composite films not exhibit obvious easy magnetization direction. The resulted short (200 nm in length) and wide (50 nm in diameter) Ni nanowires present only fcc phase. The magnetization reversal mechanism is in good agreement with the symmetric fanning reversal mode which is discussed in detail. Such films may find applications in decoration, display and multifunctional anti-counterfeiting applications.

  6. Stabilization of ultrathin (hydroxy)oxide films on transition metal substrates for electrochemical energy conversion

    NASA Astrophysics Data System (ADS)

    Zeng, Zhenhua; Chang, Kee-Chul; Kubal, Joseph; Markovic, Nenad M.; Greeley, Jeffrey

    2017-06-01

    Design of cost-effective electrocatalysts with enhanced stability and activity is of paramount importance for the next generation of energy conversion systems, including fuel cells and electrolysers. However, electrocatalytic materials generally improve one of these properties at the expense of the other. Here, using density functional theory calculations and electrochemical surface science measurements, we explore atomic-level features of ultrathin (hydroxy)oxide films on transition metal substrates and demonstrate that these films exhibit both excellent stability and activity for electrocatalytic applications. The films adopt structures with stabilities that significantly exceed bulk Pourbaix limits, including stoichiometries not found in bulk and properties that are tunable by controlling voltage, film composition, and substrate identity. Using nickel (hydroxy)oxide/Pt(111) as an example, we further show how the films enhance activity for hydrogen evolution through a bifunctional effect. The results suggest design principles for this class of electrocatalysts with simultaneously enhanced stability and activity for energy conversion.

  7. Strongly improved electrochemical cycling durability by adding iridium to electrochromic nickel oxide films.

    PubMed

    Wen, Rui-Tao; Niklasson, Gunnar A; Granqvist, Claes G

    2015-05-13

    Anodically colored nickel oxide (NiO) thin films are of much interest as counter electrodes in tungsten oxide based electrochromic devices such as "smart windows" for energy-efficient buildings. However, NiO films are prone to suffering severe charge density degradation upon prolonged electrochemical cycling, which can lead to insufficient device lifetime. Therefore, a means to improve the durability of NiO-based films is an important challenge at present. Here we report that the incorporation of a modest amount of iridium into NiO films [Ir/(Ir + Ni) = 7.6 atom %] leads to remarkable durability, exceeding 10000 cycles in a lithium-conducting electrolyte, along with significantly improved optical modulation during extended cycling. Structure characterization showed that the face-centered-cubic-type NiO structure remained after iridium addition. Moreover, the crystallinity of these films was enhanced upon electrochemical cycling.

  8. Tin Oxide Films On Glass Substrates By A SOL-GEL Technique

    NASA Astrophysics Data System (ADS)

    Puyane, R.; Kato, I.

    1983-11-01

    The novel sol-gel technique has been implemented to deposit electroconductive tin oxide films to be used as transparent electrodes, mainly for display applications. Thin films of antimony-doped tin oxide were deposited on several types of glass substrates (soda-lime-silica, borosilicate and fused silica) using a dip-coating procedure. Alcoholic solutions of tin and antimony organometallic compounds were prepared under controlled conditions. The dipcoating procedure is described° in detail as well as subsequent thermal treatments under controlled atmosphere and temperatures up to 630 C. The optical and electrical characteristics of the films were studied as a function of the process parameters, firing conditions and number of coatings. After the subsequent thermal treatments, 2film resistances of about 200 ohms square could be measured corresponding to resistivities of about 10 ohm cm. The films optical transmission was above 80 percent.

  9. Influence of gaseous annealing environment on the properties of indium-tin-oxide thin films

    NASA Astrophysics Data System (ADS)

    Wang, R. X.; Beling, C. D.; Fung, S.; Djurišić, A. B.; Ling, C. C.; Li, S.

    2005-02-01

    The influence of postannealing in different gaseous environments on the optical properties of indiu-tin-oxide (ITO) thin films deposited on glass substrates using e-beam evaporation has been systematically investigated. It is found that the annealing conditions affect the optical and electrical properties of the films. Atomic force microscopy, x-ray diffraction, and x-ray photoemission spectroscopy (XPS) were employed to obtain information on the chemical state and crystallization of the films. These data suggest that the chemical states and surface morphology of the ITO film are strongly influenced by the gaseous environment during the annealing process. The XPS data indicate that the observed variations in the optical transmittance can be explained by oxygen incorporation into the film, decomposition of the indium oxide phases, as well as the removal of metallic In.

  10. Structure and luminescence evolution of annealed Europium-doped silicon oxides films.

    PubMed

    Li, Dongsheng; Zhang, Xuwu; Jin, Lu; Yang, Deren

    2010-12-20

    Europium (Eu)-doped silicon oxide films with Eu concentrations from 2.1 to 4.7 at. % were deposited by electron beam evaporation. The Eu related luminescence from the films was found to be sensitive to the evolution of film microstructures at different annealing temperatures. Luminescence centers in the films changed from defects of silicon oxides to 4f(6)5d-4f(7)(8S(7/2)) transition of Eu2+ after the films annealed in N2 at temperature higher than 800 °C. The evolution of luminescence centers was attributed to the formation of europium silicate (EuSiO3), which was confirmed by x-ray photoelectron spectroscopy, x-ray diffraction, time resolved photoluminescence, and transmission electron microscopy.

  11. Densification of chemical vapor deposition silicon dioxide film using oxygen radical oxidation

    NASA Astrophysics Data System (ADS)

    Kawase, Kazumasa; Teramoto, Akinobu; Umeda, Hiroshi; Suwa, Tomoyuki; Uehara, Yasushi; Hattori, Takeo; Ohmi, Tadahiro

    2012-02-01

    Silicon dioxide (SiO2) films formed by chemical vapor deposition (CVD) were treated with oxygen radical oxidation using Ar/O2 plasma excited by microwave. The mass density depth profiles, carrier trap densities, and current-voltage characteristics of the radical-oxidized CVD-SiO2 films were investigated. The mass density depth profiles were estimated with x ray reflectivity measurement using synchrotron radiation of SPring-8. The carrier trap densities were estimated with x ray photoelectron spectroscopy time-dependent measurement. The mass densities of the radical-oxidized CVD-SiO2 films were increased near the SiO2 surface. The densities of the carrier trap centers in these films were decreased. The leakage currents of the metal-oxide-semiconductor capacitors fabricated by using these films were reduced. It is probable that the insulation properties of the CVD-SiO2 film are improved by the increase in the mass density and the decrease in the carrier trap density caused by the restoration of the Si-O network with the radical oxidation.

  12. Growth, interfacial alloying, and oxidation of ultra-thin Al films on Ru(0001)

    NASA Astrophysics Data System (ADS)

    Wu, Yutong; Tao, Hui-Shu; Garfunkel, Eric; Madey, Theodore E.; Shinn, Neal D.

    1995-08-01

    The growth and oxidation of ultra-thin aluminum films on Ru(0001) have been studied by low energy ion scattering (LEIS) and X-ray photoelectron spectroscopy (XPS) using both Mg K α and synchrotron soft X-ray radiation. For Al films of average thickness ˜ 15 Å deposited at 300 K, LEIS demonstrates that the Ru substrate is completely covered. Upon annealing to ˜ 1000 K LEIS shows the reappearance of Ru at the surface. At the same time, the metallic Al 2p peak shifts to lower binding energy and a low binding energy shoulder appears on the Ru 3d peak, suggesting {Al}/{Ru} interfacial alloying. Annealing Al films to ˜ 1000 K in 1 × 10 -4 Torr oxygen produces an oxidized surface layer that completely covers the Ru substrate; the resultant aluminum oxide films are stoichiometric.

  13. Tuning the Composition and Nanostructure of Pt/Ir Films via Anodized Aluminum Oxide Templated Atomic Layer Deposition

    DTIC Science & Technology

    2010-01-01

    REPORT Tuning the composition and nanostructure of Pt/Ir films via anodized aluminum oxide templated atomic layer deposition 14. ABSTRACT 16. SECURITY... oxide templates. Templated ALD provides advantages over alternative synthesis techniques, including improved film uniformity and conformality as...layer deposition, anodized aluminum oxide , platinum, iridium D. J. Comstock, S. T. Christensen, J. W. Elam, M. J. Pellin, and M. C. Hersam

  14. Oxidation and biodegradation of polyethylene films containing pro-oxidantadditives: Synergistic effects of sunlight exposure, thermal aging and fungal biodegradation

    USDA-ARS?s Scientific Manuscript database

    Synergistic effects of sunlight exposure, thermal aging and fungal biodegradation on the oxidation and biodegradation of linear low density poly (ethylene) PE-LLD films containing pro-oxidant were examined. To achieve oxidation and degradation, films were first exposed to the sunlight for 93 days du...

  15. Characterization of epitaxially grown films of vanadium oxides

    SciTech Connect

    Rogers, K.D.; Coath, J.A.; Lovell, M.C. , Shrivenham, Swindon, Wiltshire, SN6 8LA, England )

    1991-08-01

    The growth of VO{sub 2} and V{sub 2}O{sub 3} thin films by reactive sputtering has been investigated. Previously reported studies of such thin films have often presented ambiguous results concerning the precise nature of the layers produced. A thorough and comprehensive characterization program including x-ray diffraction, scanning electron microscopy, Rutherford-backscattering spectroscopy, and electrical conductivity measurements has been undertaken to ensure that the films produced were of a true epitaxial nature.

  16. Difference in charge transport properties of Ni-Nb thin films with native and artificial oxide

    SciTech Connect

    Trifonov, A. S.; Lubenchenko, A. V.; Polkin, V. I.; Pavolotsky, A. B.; Ketov, S. V.; Louzguine-Luzgin, D. V.

    2015-03-28

    Here, we report on the properties of native and artificial oxide amorphous thin film on a surface of an amorphous Ni-Nb sample. Careful measurements of local current-voltage characteristics of the system Ni-Nb / NiNb oxide/Pt, were carried out in contact mode of an atomic force microscope. Native oxide showed n-type conductivity, while in the artificial one exhibited p-type one. The shape of current-voltage characteristic curves is unique in both cases and no analogical behavior is found in the literature. X-ray photoelectron spectroscopy (XPS) measurements were used to detect chemical composition of the oxide films and the oxidation state of the alloy components. Detailed analysis of the XPS data revealed that the structure of natural Ni-Nb oxide film consists of Ni-NbO{sub x} top layer and nickel enriched bottom layer which provides n-type conductivity. In contrast, in the artificial oxide film Nb is oxidized completely to Nb{sub 2}O{sub 5}, Ni atoms migrate into bulk Ni-Nb matrix. Electron depletion layer is formed at the Ni-Nb/Nb{sub 2}O{sub 5} interface providing p-type conductivity.

  17. Nanostructured magnetic films of iron oxides fabricated by laser electrodispersion

    NASA Astrophysics Data System (ADS)

    Melekh, B. T.; Kurdyukov, D. A.; Yavsin, D. A.; Kozhevin, V. M.; Gurevich, S. A.; Gastev, S. V.; Volkov, M. P.; Sitnikova, A. A.; Yagovkina, M. A.; Pevtsov, A. B.

    2016-10-01

    Nanostructured FeO films with an average nanoparticle size of the order of 6-10 nm were fabricated by laser electrodispersion. Annealing at T = 300°C in vacuum resulted in the disproportionation of FeO particles into Fe3O4 and α-Fe, while the films exhibited a marked crystal orientation (texture with the [111] axis). The coercive force and the saturation magnetization of the synthesized nanostructured Fe3O4/α-Fe films were as large as 660 Oe and 520 emu/cm3, respectively. These values are considerably higher than the corresponding parameters of polycrystalline Fe3O4 films.

  18. Enhanced Luminescence in Epitaxial Oxide Thin-Film Phosphors

    SciTech Connect

    Lee, Y.E.; Norton, D.P.; Budai, J.D.; Park, C.; Kim, M.; Pennycook, S.J.; Rack, P.D.; Potter, M.D.

    1999-11-08

    Undoped and Mn-doped ZnGa{sub 2}O{sub 4} thin-film phosphors were grown using pulsed laser ablation on (100) MgO single crystal and glass substrates. X-ray results showed the films on (100) MgO are well aligned both out-of plane and in-plane. Epitaxial films show superior photoluminescent intensity as compared to randomly oriented polycrystalline films, indicating that intragranular crystallinity strongIy influences luminescent properties. Li-doped ZnGa{sub 2}O{sub 4} exhibited significantly enhanced photoluminescence intensity.

  19. Electrochromic performance, wettability and optical study of copper manganese oxide thin films: Effect of annealing temperature

    NASA Astrophysics Data System (ADS)

    Falahatgar, S. S.; Ghodsi, F. E.; Tepehan, F. Z.; Tepehan, G. G.; Turhan, İ.

    2014-01-01

    In the present work, the nanostructured copper manganese oxide (CMO) thin films were prepared from acetate based sol-gel precursors and deposited on glass and indium tin oxide (ITO) substrates by dip-coating technique. The films were annealed at 300, 400 and 500 °C in ambient atmosphere. The effects of annealing temperature on structural, morphological, wettability, electrochromic and optical properties of CMO thin films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDX), water contact angle measurement (WCA), cyclic voltammetry (CV) measurements and ultraviolet-visible (UV-vis) spectrophotometery. The presence of mixed oxide phases comprising of copper manganese oxide (CuMn2O4) and manganese oxide at different annealing temperature was confirmed by XRD patterns. The results showed that the Mn3O4 phase has been changed to Mn2O3 when the annealing temperature is increased from 300 to 500 °C. The FESEM images indicated that the granular surface morphology was sensitive to annealing temperature. EDX studies indicated that the thin films contained O, Mn and Cu species. Wettability studies showed that the water contact angle of the nanostructured CMO thin films coated on glass substrates was influenced by the variation of annealing temperature and the surface nature of thin films was changed from hydrophilic to hydrophobic. The results of CVs measurement indicated that the anodic and cathodic charge density and capacitance of all CMO samples decreased with increasing scan rate in potential range of -1-1 eV. Also, the annealed CMO thin film at 500 °C showed better electrochromic performance with respect to other samples at lower scan rate. The thickness, refractive index, extinction coefficient and optical band gap of thin films coated on glass substrates were calculated from reflectance and transmittance spectra using an iterative numerical method. The optical band gap of

  20. Structural, morphological and electrical properties of nickel oxide thin films deposited by reactive sputtering

    NASA Astrophysics Data System (ADS)

    Keraudy, J.; García Molleja, J.; Ferrec, A.; Corraze, B.; Richard-Plouet, M.; Goullet, A.; Jouan, P.-Y.

    2015-12-01

    This paper is devoted to the study of the influence of oxygen content in the nickel oxide films on the film structural, morphological and electrical properties. Nickel oxide films have been synthesized by reactive DC magnetron sputtering discharge by varying the oxygen flow rate (1.9 < Q(O2) < 3.6 sccm) for various deposition time. XRD analyses revealed the polycrystalline nature of the as-deposited films and also a phase transition from nickel oxide (1 1 1) to nickel oxide (2 0 0) associated with nickel non-stoichiometry in the NiO structure. The polycrystalline films presented an average crystallite size of 15-30 nm and a surface roughness of 1-10 nm. In-plane stress measurements have established the correlation between crystallite size and intrinsic compressive stress and also the ion-penning effect of negative oxygen ions during the film growth. A maximum stress of 10 GPa was found for lower film thickness (10 nm). By adjusting the oxygen concentration, conductive AFM (C-AFM) and resistivity measurements by the four point method have revealed at room temperature an electrical transition from insulating to conductive state. C-AFM and four point measurements showed respectively an increase in the collected current and an abrupt decrease of the mean resistivity from 107 to 10 Ω cm when the stoichiometry varies from NiO0.96 to NiO1.14. This transition is related to the non-stoichiometry attributed to nickel vacancies. Finally, low-temperature (290-100 K) electrical conduction measurements confirmed the weak dependence of Ni-deficient nickel oxide films with film thickness and showed that charge carrier conduction is a thermal-activated process.

  1. Self-assembly of a thin highly reduced graphene oxide film and its high electrocatalytic activity

    NASA Astrophysics Data System (ADS)

    Bai, Yan-Feng; Zhang, Yong-Fang; Zhou, An-Wei; Li, Hai-Wai; Zhang, Yu; Luong, John H. T.; Cui, Hui-Fang

    2014-10-01

    A thin highly reduced graphene oxide (rGO) film was self-assembled at the dimethyl formamide (DMF)-air interface through evaporation-induced water-assisted thin film formation at the pentane-DMF interface, followed by complete evaporation of pentane. The thin film was transferred onto various solid substrates for film characterization and electrochemical sensing. UV-visible spectrometry, scanning electron microscopy (SEM), atomic force microscopy (AFM) and electrochemistry techniques were used to characterize the film. An rGO film showing 82.8% of the transmittance at 550 nm corresponds to a few layers of rGO nanosheets. The rGO nanosheets cross-stack with each other, lying approximately in the plane of the film. An rGO film collected on a glassy carbon (GC) electrode exhibited improved electrical conductivity compared to GC, with the electrode charge-transfer resistance (Rct) reduced from 31 Ω to 22 Ω. The as-formed rGO/GC electrode was mechanically very stable, exhibiting significantly enhanced electrocatalytic activity to H2O2 and dopamine. Multiple layers of the rGO films on the GC electrode showed even stronger electrocatalytic activity to dopamine than that of the single rGO film layer. The controllable formation of a stable rGO film on various solid substrates has potential applications for nanoelectronics and sensors/biosensors.

  2. Self-assembly of a thin highly reduced graphene oxide film and its high electrocatalytic activity.

    PubMed

    Bai, Yan-Feng; Zhang, Yong-Fang; Zhou, An-Wei; Li, Hai-Wai; Zhang, Yu; Luong, John H T; Cui, Hui-Fang

    2014-10-10

    A thin highly reduced graphene oxide (rGO) film was self-assembled at the dimethyl formamide (DMF)-air interface through evaporation-induced water-assisted thin film formation at the pentane-DMF interface, followed by complete evaporation of pentane. The thin film was transferred onto various solid substrates for film characterization and electrochemical sensing. UV-visible spectrometry, scanning electron microscopy (SEM), atomic force microscopy (AFM) and electrochemistry techniques were used to characterize the film. An rGO film showing 82.8% of the transmittance at 550 nm corresponds to a few layers of rGO nanosheets. The rGO nanosheets cross-stack with each other, lying approximately in the plane of the film. An rGO film collected on a glassy carbon (GC) electrode exhibited improved electrical conductivity compared to GC, with the electrode charge-transfer resistance (Rct) reduced from 31 Ω to 22 Ω. The as-formed rGO/GC electrode was mechanically very stable, exhibiting significantly enhanced electrocatalytic activity to H(2)O(2) and dopamine. Multiple layers of the rGO films on the GC electrode showed even stronger electrocatalytic activity to dopamine than that of the single rGO film layer. The controllable formation of a stable rGO film on various solid substrates has potential applications for nanoelectronics and sensors/biosensors.

  3. Effect of silver incorporation in phase formation and band gap tuning of tungsten oxide thin films

    SciTech Connect

    Jolly Bose, R.; Kumar, R. Vinod; Sudheer, S. K.; Mahadevan Pillai, V. P.; Reddy, V. R.; Ganesan, V.

    2012-12-01

    Silver incorporated tungsten oxide thin films are prepared by RF magnetron sputtering technique. The effect of silver incorporation in micro structure evolution, phase enhancement, band gap tuning and other optical properties are investigated using techniques such as x-ray diffraction, micro-Raman spectroscopy, atomic force microscopy, scanning electron microscopy, energy dispersive x-ray spectroscopy, and UV-Visible spectroscopy. Effect of silver addition in phase formation and band gap tuning of tungsten oxide thin films are investigated. It is found that the texturing and phase formation improves with enhancement in silver content. It is also found that as the silver incorporation enhances the thickness of the films increases at the same time the strain in the film decreases. Even without annealing the desired phase can be achieved by doping with silver. A broad band centered at the wavelength 437 nm is observed in the absorption spectra of tungsten oxide films of higher silver incorporation and this can be attributed to surface plasmon resonance of silver atoms present in the tungsten oxide matrix. The transmittance of the films is decreased with increase in silver content which can be due to increase in film thickness, enhancement of scattering, and absorption of light caused by the increase of grain size, surface roughness and porosity of films and enhanced absorption due to surface plasmon resonance of silver. It is found that silver can act as the seed for the growth of tungsten oxide grains and found that the grain size increases with silver content which in turn decreases the band gap of tungsten oxide from 3.14 eV to 2.70 eV.

  4. Morphology control of zinc oxide films via polysaccharide-mediated, low temperature, chemical bath deposition

    PubMed Central

    Schneider, Andreas M; Eiden, Stefanie

    2015-01-01

    Summary In this study we present a three-step process for the low-temperature chemical bath deposition of crystalline ZnO films on glass substrates. The process consists of a seeding step followed by two chemical bath deposition steps. In the second step (the first of the two bath deposition steps), a natural polysaccharide, namely hyaluronic acid, is used to manipulate the morphology of the films. Previous experiments revealed a strong influence of this polysaccharide on the formation of zinc oxide crystallites. The present work aims to transfer this gained knowledge to the formation of zinc oxide films. The influence of hyaluronic acid and the time of its addition on the morphology of the resulting ZnO film were investigated. By meticulous adjustment of the parameters in this step, the film morphology can be tailored to provide an optimal growth platform for the third step (a subsequent chemical bath deposition step). In this step, the film is covered by a dense layer of ZnO. This optimized procedure leads to ZnO films with a very high electrical conductivity, opening up interesting possibilities for applications of such films. The films were characterized by means of electron microscopy, X-ray diffraction and measurements of the electrical conductivity. PMID:25977851

  5. The growth and evolution of thin oxide films on delta-plutonium surfaces

    SciTech Connect

    Garcia Flores, Harry G; Pugmire, David L

    2009-01-01

    The common oxides of plutonium are the dioxide (PuO{sub 2}) and the sesquioxide (Pu{sub 2}O{sub 3}). The structure of an oxide on plutonium metal under air at room temperature is typically described as a thick PuO{sub 2} film at the gas-oxide interface with a thinner PuO{sub 2} film near the oxide-metal substrate interface. In a reducing environment, such as ultra high vacuum, the dioxide (Pu{sup 4+}; O/Pu = 2.0) readily converts to the sesquioxide (Pu{sup 3+}; O/Pu = 1.5) with time. In this work, the growth and evolution of thin plutonium oxide films is studied with x-ray photoelectron spectroscopy (XPS) under varying conditions. The results indicate that, like the dioxide, the sesquioxide is not stable on a very clean metal substrate under reducing conditions, resulting in substoichiometric films (Pu{sub 2}O{sub 3-y}). The Pu{sub 2}O{sub 3-y} films prepared exhibit a variety of stoichiometries (y = 0.2-1) as a function of preparation conditions, highlighting the fact that caution must be exercised when studying plutonium oxide surfaces under these conditions and interpreting resulting data.

  6. Double Oxide Film Defects in Al Castings and the Effect of Different Element Additions

    NASA Astrophysics Data System (ADS)

    Chen, Q.; Caden, A. J.; Griffiths, W. D.

    Double oxide film defects consist of doubled-over oxide films containing a gas-filled crevice, and are reported to cause both reductions in mechanical properties and increases in the scatter of properties in Al alloy castings. However, the gas entrapped in a double oxide film defect during its formation may be consumed by reaction with the surrounding melt. The defect might then be closed and its harmful effects might be reduced. In the experiments reported here, an air bubble was trapped inside an Al melt for up to 1 hour. The change in the volume of the bubble was determined and the oxide film created was investigated using SEM/EDX. The experiment was conducted with additions of Ti, Zr, Mo, Hf, Sc to commercial pure aluminum and 2L99 Al alloy, and it was found that the Mo addition affected the formation of the oxide layer and might therefore accelerate the consumption of the entrapped gas. Tensile testing of sand-cast 2L99 alloy with an addition of Mo suggested that with the Mo addition the Weibull modulus for Ultimate Tensile Strength was increased. Investigation of the fracture surfaces of the test bars suggested mechanisms of how this addition may affect double oxide film defects.

  7. Preparation of Aluminum Nanomesh Thin Films from an Anodic Aluminum Oxide Template as Transparent Conductive Electrodes

    PubMed Central

    Li, Yiwen; Chen, Yulong; Qiu, Mingxia; Yu, Hongyu; Zhang, Xinhai; Sun, Xiao Wei; Chen, Rui

    2016-01-01

    We have employed anodic aluminum oxide as a template to prepare ultrathin, transparent, and conducting Al films with a unique nanomesh structure for transparent conductive electrodes. The anodic aluminum oxide template is obtained through direct anodization of a sputtered Al layer on a glass substrate, and subsequent wet etching creates the nanomesh metallic film. The optical and conductive properties are greatly influenced by experimental conditions. By tuning the anodizing time, transparent electrodes with appropriate optical transmittance and sheet resistance have been obtained. The results demonstrate that our proposed strategy can serve as a potential method to fabricate low-cost TCEs to replace conventional indium tin oxide materials. PMID:26831759

  8. Preparation of Aluminum Nanomesh Thin Films from an Anodic Aluminum Oxide Template as Transparent Conductive Electrodes.

    PubMed

    Li, Yiwen; Chen, Yulong; Qiu, Mingxia; Yu, Hongyu; Zhang, Xinhai; Sun, Xiao Wei; Chen, Rui

    2016-02-02

    We have employed anodic aluminum oxide as a template to prepare ultrathin, transparent, and conducting Al films with a unique nanomesh structure for transparent conductive electrodes. The anodic aluminum oxide template is obtained through direct anodization of a sputtered Al layer on a glass substrate, and subsequent wet etching creates the nanomesh metallic film. The optical and conductive properties are greatly influenced by experimental conditions. By tuning the anodizing time, transparent electrodes with appropriate optical transmittance and sheet resistance have been obtained. The results demonstrate that our proposed strategy can serve as a potential method to fabricate low-cost TCEs to replace conventional indium tin oxide materials.

  9. Assessing the antimicrobial activity of zinc oxide thin films using disk diffusion and biofilm reactor

    NASA Astrophysics Data System (ADS)

    Gittard, Shaun D.; Perfect, John R.; Monteiro-Riviere, Nancy A.; Wei, Wei; Jin, Chunming; Narayan, Roger J.

    2009-03-01

    The electronic and chemical properties of semiconductor materials may be useful in preventing growth of microorganisms. In this article, in vitro methods for assessing microbial growth on semiconductor materials will be presented. The structural and biological properties of silicon wafers coated with zinc oxide thin films were evaluated using atomic force microscopy, X-ray photoelectron spectroscopy, and MTT viability assay. The antimicrobial properties of zinc oxide thin films were established using disk diffusion and CDC Biofilm Reactor studies. Our results suggest that zinc oxide and other semiconductor materials may play a leading role in providing antimicrobial functionality to the next-generation medical devices.

  10. The effect of hydrogen peroxide on uranium oxide films on 316L stainless steel

    NASA Astrophysics Data System (ADS)

    Wilbraham, Richard J.; Boxall, Colin; Goddard, David T.; Taylor, Robin J.; Woodbury, Simon E.

    2015-09-01

    For the first time the effect of hydrogen peroxide on the dissolution of electrodeposited uranium oxide films on 316L stainless steel planchets (acting as simulant uranium-contaminated metal surfaces) has been studied. Analysis of the H2O2-mediated film dissolution processes via open circuit potentiometry, alpha counting and SEM/EDX imaging has shown that in near-neutral solutions of pH 6.1 and at [H2O2] ⩽ 100 μmol dm-3 the electrodeposited uranium oxide layer is freely dissolving, the associated rate of film dissolution being significantly increased over leaching of similar films in pH 6.1 peroxide-free water. At H2O2 concentrations between 1 mmol dm-3 and 0.1 mol dm-3, formation of an insoluble studtite product layer occurs at the surface of the uranium oxide film. In analogy to corrosion processes on common metal substrates such as steel, the studtite layer effectively passivates the underlying uranium oxide layer against subsequent dissolution. Finally, at [H2O2] > 0.1 mol dm-3 the uranium oxide film, again in analogy to common corrosion processes, behaves as if in a transpassive state and begins to dissolve. This transition from passive to transpassive behaviour in the effect of peroxide concentration on UO2 films has not hitherto been observed or explored, either in terms of corrosion processes or otherwise. Through consideration of thermodynamic solubility product and complex formation constant data, we attribute the transition to the formation of soluble uranyl-peroxide complexes under mildly alkaline, high [H2O2] conditions - a conclusion that has implications for the design of both acid minimal, metal ion oxidant-free decontamination strategies with low secondary waste arisings, and single step processes for spent nuclear fuel dissolution such as the Carbonate-based Oxidative Leaching (COL) process.

  11. Measurement of faradaic current during AFM local oxidation of magnetic metal thin films

    NASA Astrophysics Data System (ADS)

    Takemura, Yasushi; Shimada, Yasuyuki; Watanabe, Genta; Yamada, Tsutomu; Shirakashi, Jun-ichi

    2007-04-01

    Faradaic current during a local oxidation using an atomic force microscope was studied. The intensity of the measured faradaic current was increased with increasing bias voltage applied to a cantilever, resulting in fabrication of larger size of nano-oxide structures on Si substrates. On the other hand, an excess current (over current) that was considered not to contribute the oxidation reaction was observed noticeably in the local oxidation of NiFe thin films. It was found that the excess current could be suppressed by depositing insulating oxide layers on the surfaces. The surface oxide layers were also advantageous for stable existence of meniscus promoting the local oxidation because of their hydrophilic properties. This method of capped oxide layers is significant for stable performance of the local oxidation technique fabricating nanostructures and nano-devices.

  12. Ion-beam and dual-ion-beam sputter deposition of tantalum oxide films

    NASA Astrophysics Data System (ADS)

    Cevro, Mirza; Carter, George

    1995-02-01

    Ion-beam sputter deposition (IBS) and dual-ion-beam sputter deposition (DIBS) of tantalum oxide films was investigated at room temperature and compared with similar films prepared by e-gun deposition. The optical properties, i.e., refractive index and extinction coefficient, of IBS films were determined in the 250- to 1100-nm range by transmission spectrophotometry and at (lambda) equals 632.8 nm by ellipsometry. They were found to be mainly sensitive to the partial pressure of oxygen used as a reactive gas in the deposition process. The maximum value of the refractive index of IBS deposited tantalum oxide films was n equals 2.15 at (lambda) equals 550 nm and the extinction coefficient of order k equals 2 X 10-4. Films deposited by e-gun deposition had refractive index n 2.06 at (lambda) equals 550 nm. Films deposited using DIBS, i.e., deposition assisted by low energy Ar and O2 ions (Ea equals 0 to 300 eV) and low current density (Ji equals 0 to 40 (mu) A/cm2), showed no improvement in the optical properties of the films. Preferential sputtering occurred at Ea(Ar) equals 300 eV and Ji equals 20 (mu) A/cm2 and slightly oxygen deficient films were formed. Different bonding states in the tantalum-oxide films were determined by x-ray spectroscopy, whereas composition of the film and contaminants were determined by Rutherford backscattering spectroscopy (RBS). Tantalum oxide films formed by IBS contained relatively high Ar content (approximately equals 2.5%) originating from the reflected argon neutrals from the sputtering target whereas assisted deposition slightly increased the Ar content. Stress in the IBS-deposited films was measured by the bending technique. IBS-deposited films showed compressive stress with a typical value of s equals 3.2 X 109 dyn/cm2. Films deposited by concurrent ion bombardment showed an increase in the stress as a function of applied current density. The maximum was s approximately equals 5.6 X 109 dyn/cm2 for Ea equals 300 eV and Ji equals

  13. Ion beam and dual ion beam sputter deposition of tantalum oxide films

    NASA Astrophysics Data System (ADS)

    Cevro, Mirza; Carter, George

    1994-11-01

    Ion beam sputter deposition (IBS) and dual ion beam sputter deposition (DIBS) of tantalum oxide films was investigated at room temperature and compared with similar films prepared by e-gun deposition. Optical properties ie refractive index and extinction coefficient of IBS films were determined in the 250 - 1100 nm range by transmission spectrophotometry and at (lambda) equals 632.8 nm by ellipsometry. They were found to be mainly sensitive to the partial pressure of oxygen used as a reactive gas in the deposition process. The maximum value of the refractive index of IBS deposited tantalum oxide films was n equals 2.15 at (lambda) equals 550 nm and the extinction coefficient of order k equals 2 X 10-4. Films deposited by e-gun deposition had refractive index n equals 2.06 at (lambda) equals 550 nm. Films deposited using DIBS ie deposition assisted by low energy Ar and O2 ions (Ea equals 0 - 300 eV) and low current density (Ji equals 0 - 40 (mu) A/cm2) showed no improvement in the optical properties of the films. Preferential sputtering occurred at Ea(Ar) equals 300 eV and Ji equals 20 (mu) A/cm2 and slightly oxygen deficient films were formed. Different bonding states in the tantalum-oxide films were determined by x-ray spectroscopy while composition of the film and contaminants were determined by Rutherford scattering spectroscopy. Tantalum oxide films formed by IBS contained relatively high Ar content (approximately equals 2.5%) originating from the reflected argon neutrals from the sputtering target while assisted deposition slightly increased the Ar content. Stress in the IBS deposited films was measured by the bending technique. IBS deposited films showed compressive stress with a typical value of s equals 3.2 X 109 dyn/cm2. Films deposited by concurrent ion bombardment showed an increase in the stress as a function of applied current density. The maximum was s approximately equals 5.6 X 109 dyn/cm2 for Ea equals 300 eV and Ji equals 35 (mu) A/cm2. All

  14. Iron Oxide Films Prepared by Rapid Thermal Processing for Solar Energy Conversion

    NASA Astrophysics Data System (ADS)

    Wickman, B.; Bastos Fanta, A.; Burrows, A.; Hellman, A.; Wagner, J. B.; Iandolo, B.

    2017-01-01

    Hematite is a promising and extensively investigated material for various photoelectrochemical (PEC) processes for energy conversion and storage, in particular for oxidation reactions. Thermal treatments during synthesis of hematite are found to affect the performance of hematite electrodes considerably. Herein, we present hematite thin films fabricated via one-step oxidation of Fe by rapid thermal processing (RTP). In particular, we investigate the effect of oxidation temperature on the PEC properties of hematite. Films prepared at 750 °C show the highest activity towards water oxidation. These films show the largest average grain size and the highest charge carrier density, as determined from electron microscopy and impedance spectroscopy analysis. We believe that the fast processing enabled by RTP makes this technique a preferred method for investigation of novel materials and architectures, potentially also on nanostructured electrodes, where retaining high surface area is crucial to maximize performance.

  15. Iron Oxide Films Prepared by Rapid Thermal Processing for Solar Energy Conversion

    PubMed Central

    Wickman, B.; Bastos Fanta, A.; Burrows, A.; Hellman, A.; Wagner, J. B.; Iandolo, B.

    2017-01-01

    Hematite is a promising and extensively investigated material for various photoelectrochemical (PEC) processes for energy conversion and storage, in particular for oxidation reactions. Thermal treatments during synthesis of hematite are found to affect the performance of hematite electrodes considerably. Herein, we present hematite thin films fabricated via one-step oxidation of Fe by rapid thermal processing (RTP). In particular, we investigate the effect of oxidation temperature on the PEC properties of hematite. Films prepared at 750 °C show the highest activity towards water oxidation. These films show the largest average grain size and the highest charge carrier density, as determined from electron microscopy and impedance spectroscopy analysis. We believe that the fast processing enabled by RTP makes this technique a preferred method for investigation of novel materials and architectures, potentially also on nanostructured electrodes, where retaining high surface area is crucial to maximize performance. PMID:28091573

  16. Pulsed laser deposition of transparent conductive oxide thin films on flexible substrates

    NASA Astrophysics Data System (ADS)

    Socol, G.; Socol, M.; Stefan, N.; Axente, E.; Popescu-Pelin, G.; Craciun, D.; Duta, L.; Mihailescu, C. N.; Mihailescu, I. N.; Stanculescu, A.; Visan, D.; Sava, V.; Galca, A. C.; Luculescu, C. R.; Craciun, V.

    2012-11-01

    The influence of target-substrate distance during pulsed laser deposition of indium zinc oxide (IZO), indium tin oxide (ITO) and aluminium-doped zinc oxide (AZO) thin films grown on polyethylene terephthalate (PET) substrates was investigated. It was found that the properties of such flexible transparent conductive oxide (TCO)/PET electrodes critically depend on this parameter. The TCO films that were deposited at distances of 6 and 8 cm exhibited an optical transmittance higher than 90% in the visible range and electrical resistivities around 5 × 10-4 Ω cm. In addition to these excellent electrical and optical characteristics the films grown at 8 cm distance were homogenous, smooth, adherent, and without cracks or any other extended defects, being suitable for opto-electronic device applications.

  17. Oxygen release and structural changes in TiO2 films during photocatalytic oxidation

    NASA Astrophysics Data System (ADS)

    Yoshida, Kenta; Nanbara, Takahiro; Yamasaki, Jun; Tanaka, Nobuo

    2006-04-01

    Changes in the crystal structure and grain modifications in titanium oxide (TiO2) thin films were observed during the photocatalytic oxidation of hydrocarbons. When the hydrocarbon and collodion films were irradiated, single crystalline titanium oxide transformed into polycrystals. The titanium oxide films gradually became network aggregates. These changes were analyzed with a dedicated in situ transmission electron microscope and observed three dimensionally by electron tomography. A detailed analysis of electron energy loss spectra of the samples also revealed that the changes were associated with the loss of oxygen atoms in the TiO2 crystal lattice. Correlations between the polycrystalline grain size of TiO2 and its catalyst activity were discussed based on the measured data.

  18. Intrinsic stress evolution during amorphous oxide film growth on Al surfaces

    SciTech Connect

    Flötotto, D. Wang, Z. M.; Jeurgens, L. P. H.; Mittemeijer, E. J.

    2014-03-03

    The intrinsic stress evolution during formation of ultrathin amorphous oxide films on Al(111) and Al(100) surfaces by thermal oxidation at room temperature was investigated in real-time by in-situ substrate curvature measurements and detailed atomic-scale microstructural analyses. During thickening of the oxide a considerable amount of growth stresses is generated in, remarkably even amorphous, ultrathin Al{sub 2}O{sub 3} films. The surface orientation-dependent stress evolutions during O adsorption on the bare Al surfaces and during subsequent oxide-film growth can be interpreted as a result of (i) adsorption-induced surface stress changes and (ii) competing processes of free volume generation and structural relaxation, respectively.

  19. Luminescence of europium-doped anode oxide films on titanium-aluminum composites

    NASA Astrophysics Data System (ADS)

    Sokol, V. A.; Pinaeva, M. M.; Gurskaya, E. A.; Stekol'Nikov, A. A.

    2000-03-01

    The luminescence of europium in anode oxide films (AOF) on titanium-aluminum film composites is investigated. It is shown that the intensity distribution in the continuous and line luminescence spectra of europium introduced into the AOF directly in the process of anodic oxidation essentially depends on the sequence of arrangement of the layers of metal films and on the temperature of their heat treatment preceding the process of anodic oxidation. It is established that the nature of the luminescence spectrum of the AOF correlates with the chronovoltammetry diagrams of anodic oxidation. Composites with a high degree of europium doping are found and methods of searching for composites for creating new materials of electronic technology are outlined.

  20. Correction: Enhanced photoelectrochemical water oxidation via atomic layer deposition of TiO2 on fluorine-doped tin oxide nanoparticle films

    NASA Astrophysics Data System (ADS)

    Cordova, Isvar A.; Peng, Qing; Ferrall, Isa L.; Rieth, Adam J.; Hoertz, Paul G.; Glass, Jeffrey T.

    2015-07-01

    Correction for `Enhanced photoelectrochemical water oxidation via atomic layer deposition of TiO2 on fluorine-doped tin oxide nanoparticle films' by Isvar A. Cordova, et al., Nanoscale, 2015, 7, 8584-8592.

  1. Correction: Enhanced photoelectrochemical water oxidation via atomic layer deposition of TiO2 on fluorine-doped tin oxide nanoparticle films.

    PubMed

    Cordova, Isvar A; Peng, Qing; Ferrall, Isa L; Rieth, Adam J; Hoertz, Paul G; Glass, Jeffrey T

    2015-07-28

    Correction for 'Enhanced photoelectrochemical water oxidation via atomic layer deposition of TiO2 on fluorine-doped tin oxide nanoparticle films' by Isvar A. Cordova, et al., Nanoscale, 2015, 7, 8584-8592.

  2. Tungsten oxide-Au nanosized film composites for glucose oxidation and sensing in neutral medium.

    PubMed

    Gougis, Maxime; Ma, Dongling; Mohamedi, Mohamed

    2015-01-01

    In this work, we report for the first time the use of tungsten oxide (WOx) as catalyst support for Au toward the direct electrooxidation of glucose. The nanostructured WOx/Au electrodes were synthesized by means of laser-ablation technique. Both micro-Raman spectroscopy and transmission electron microscopy showed that the produced WOx thin film is amorphous and made of ultrafine particles of subnanometer size. X-ray diffraction and X-ray photoelectron spectroscopy revealed that only metallic Au was present at the surface of the WOx/Au composite, suggesting that the WOx support did not alter the electronic structure of Au. The direct electrocatalytic oxidation of glucose in neutral medium such as phosphate buffered saline (pH 7.2) solution has been investigated with cyclic voltammetry, chronoamperometry, and square-wave voltammetry. Sensitivity as high as 65.7 μA cm(-2) mM(-1) up to 10 mM of glucose and a low detection limit of 10 μM were obtained with square-wave voltammetry. This interesting analytical performance makes the laser-fabricated WOx/Au electrode potentially promising for implantable glucose fuel cells and biomedical analysis as the evaluation of glucose concentration in biological fluids. Finally, owing to its unique capabilities proven in this work, it is anticipated that the laser-ablation technique will develop as a fabrication tool for chip miniature-sized sensors in the near future.

  3. Tungsten oxide-Au nanosized film composites for glucose oxidation and sensing in neutral medium

    PubMed Central

    Gougis, Maxime; Ma, Dongling; Mohamedi, Mohamed

    2015-01-01

    In this work, we report for the first time the use of tungsten oxide (WOx) as catalyst support for Au toward the direct electrooxidation of glucose. The nanostructured WOx/Au electrodes were synthesized by means of laser-ablation technique. Both micro-Raman spectroscopy and transmission electron microscopy showed that the produced WOx thin film is amorphous and made of ultrafine particles of subnanometer size. X-ray diffraction and X-ray photoelectron spectroscopy revealed that only metallic Au was present at the surface of the WOx/Au composite, suggesting that the WOx support did not alter the electronic structure of Au. The direct electrocatalytic oxidation of glucose in neutral medium such as phosphate buffered saline (pH 7.2) solution has been investigated with cyclic voltammetry, chronoamperometry, and square-wave voltammetry. Sensitivity as high as 65.7 μA cm−2 mM−1 up to 10 mM of glucose and a low detection limit of 10 μM were obtained with square-wave voltammetry. This interesting analytical performance makes the laser-fabricated WOx/Au electrode potentially promising for implantable glucose fuel cells and biomedical analysis as the evaluation of glucose concentration in biological fluids. Finally, owing to its unique capabilities proven in this work, it is anticipated that the laser-ablation technique will develop as a fabrication tool for chip miniature-sized sensors in the near future. PMID:25931820

  4. Analysis of Zinc Oxide Thin Films Synthesized by Sol-Gel via Spin Coating

    NASA Astrophysics Data System (ADS)

    Wolgamott, Jon Carl

    Transparent conductive oxides are gaining an increasingly important role in optoelectronic devices such as solar cells. Doped zinc oxide is a candidate as a low cost and nontoxic alternative to tin doped indium oxide. Lab results have shown that both n-type and p-type zinc oxide can be created on a small scale. This can allow zinc oxide to be used as either an electrode as well as a buffer layer to increase efficiency and protect the active layer in solar cells. Sol-gel synthesis is emerging as a low temperature, low cost, and resource efficient alternative to producing transparent conducting oxides such as zinc oxide. For sol-gel derived zinc oxide thin films to reach their potential, research in this topic must continue to optimize the known processing parameters and expand to new parameters to tighten control and create novel processing techniques that improve performance. The processing parameters of drying and annealing temperatures as well as cooling rate were analyzed to see their effect on the structure of the prepared zinc oxide thin films. There were also preliminary tests done to modify the sol-gel process to include silver as a dopant to produce a p-type thin film. The results from this work show that the pre- and post- heating temperatures as well as the cooling rate all play their own unique role in the crystallization of the film. Results from silver doping show that more work needs to be done to create a sol-gel derived p-type zinc oxide thin film.

  5. Synthesis and characterization of hafnium oxide films for thermo and photoluminescence applications.

    PubMed

    Mendoza, J Guzmán; Frutis, M A Aguilar; Flores, G Alarcón; Hipólito, M García; Maciel Cerda, A; Azorín Nieto, J; Montalvo, T Rivera; Falcony, C

    2010-01-01

    Hafnium oxide (HfO(2)) films were deposited by the ultrasonic spray pyrolysis process. The films were synthesized from hafnium chloride as raw material in deionized water as solvent and were deposited on corning glass substrates at temperatures from 300 to 600 degrees C. For substrate temperatures lower than 400 degrees C the deposited films were amorphous, while for substrate temperatures higher than 450 degrees C, the monoclinic phase of HfO(2) appeared. Scanning electron microscopy showed that the film's surface resulted rough with semi-spherical promontories. The films showed a chemical composition close to HfO(2), with an Hf/O ratio of about 0.5. UV radiation was used in order to achieve the thermoluminescent characterization of the films; the 240 nm wavelength induced the best response. In addition, preliminary photoluminescence spectra, as a function of the deposition temperatures, are shown. Copyright 2009 Elsevier Ltd. All rights reserved.

  6. Electrochromic properties of WO3 thin film onto gold nanoparticles modified indium tin oxide electrodes

    NASA Astrophysics Data System (ADS)

    Deng, Jiajia; Gu, Ming; Di, Junwei

    2011-04-01

    Gold nanoparticles (GNPs) thin films, electrochemically deposited from hydrogen tetrachloroaurate onto transparent indium tin oxide (ITO) thin film coated glass, have different color prepared by variation of the deposition condition. The color of GNP film can vary from pale red to blue due to different particle size and their interaction. The characteristic of GNPs modified ITO electrodes was studied by UV-vis spectroscopy, scanning electron microscope (SEM) images and cyclic voltammetry. WO3 thin films were fabricated by sol-gel method onto the surface of GNPs modified electrode to form the WO3/GNPs composite films. The electrochromic properties of WO3/GNPs composite modified ITO electrode were investigated by UV-vis spectroscopy and cyclic voltammetry. It was found that the electrochromic performance of WO3/GNPs composite films was improved in comparison with a single component system of WO3.

  7. Electrical and optical properties of indium zinc oxide (IZO) thin films by continuous composition spread.

    PubMed

    Lee, J J; Kim, J S; Yoon, S J; Cho, Y S; Choi, J W

    2013-05-01

    Indium zinc oxide (IZO) films were deposited on glass substrate at room temperature using off-axis RF sputtering-continuous composition spread (CCS) system. The full range composition of IZO films were controlled by the deposition rate and thickness profiles of In2O3 and ZnO target. The structural, electrical and optical properties of IZO thin films were measured as functions of position. IZO thin film had the lowest resistivity and highest carrier concentration at the position of 15 mm (5.02 x 10(-4) omega cm, 3.9 x 10(20)/cm3). And IZO thin film had high transmittance in visible region at measured all positions. This study has investigated to explore the new composition of IZO films using CCS system.

  8. Reduced graphene oxide based silver sulfide hybrid films formed at a liquid/liquid interface

    SciTech Connect

    Bramhaiah, K. John, Neena S.

    2014-04-24

    Free-standing, ultra-thin films of silver sulfide and reduced graphene oxide (RGO) based silver sulfide hybrids are prepared at a liquid/liquid interface employing in situ chemical reaction strategy. Ag{sub 2}S and RGO−Ag{sub 2}S hybrid films are characterized by various techniques such as UV-visible and photo luminescence spectroscopy, X-ray diffraction and scanning electron microscopy. The morphology of hybrid films consists of Ag{sub 2}S nanocrystals on RGO surface while Ag{sub 2}S films contains branched network of dendritic structures. RGO−Ag{sub 2}S exhibit interesting optical and electrical properties. The hybrid films absorb in the region 500–650 nm and show emission in the red region. A higher conductance is observed for the hybrid films arising from the RGO component. This simple low cost method can be extended to prepare other RGO based metal sulfides.

  9. Structural properties of indium tin oxide thin films prepared for application in solar cells

    SciTech Connect

    Gheidari, A. Mohammadi; Mohajerzadeh, S.; Shams-Kolahi, W.

    2005-08-11

    Indium tin oxide (ITO) thin films prepared by rf sputtering were annealed in several temperatures. The electrical, optical and structural properties of these films are systematically investigated. The post annealing of the samples lead to considerably higher electrical conductivity, better optical transparency and larger grain size for the films. In an optimum annealing temperature of 400 deg. C, we have found that a maximized conductivity of films is achieved without a remarkable loss in their transparency. The sheet resistance of 2.3 {omega}/{open_square} and average grain size of 30 nm, are the results of the optimized post processing of films. The investigation for microstructure of films investigated by X-ray diffraction measurement (XRD) shows that a preferential crystal growth toward the (2 2 2) orientation takes place when the annealing temperature increases to 400 deg. C.

  10. Atomistic aspects of carrier concentration variation in post-annealed indium tin oxide films

    NASA Astrophysics Data System (ADS)

    Kim, Ji-Woong; Kim, Hyegyeong; Lee, Min-Young; Lee, Doo-Yong; Lee, Ji-Sung; Jang, Yun Hyeong; Bae, Jong-Seong; Lee, Jeong-Soo; Park, Sungkyun

    2015-10-01

    Post-annealing environment-dependent optical and electrical properties of indium tin oxide films grown on glass were examined. X-ray diffraction measurements revealed that all of the films exhibited poly-crystallinity after annealing at 400 °C for 10 min O2, in-air and N2. The optical property measurements yielded  >80% transmittances for all the films except for the as-grown and O2-annealed films, even though there were no significant optical band-gap energy differences. In the Hall measurements, all of the films exhibited n-type characteristics. However, the film annealed under the N2 environment showed the best electrical properties (highest carrier concentration and conductivity). The physical origin of electrical property variations due to annealing environment differences was explained by examining the core-level x-ray photoelectron spectra.

  11. Sensor activity in pulsed laser deposited and ion implanted tin oxide thin films

    NASA Astrophysics Data System (ADS)

    Lal, Ram; Grover, Rajni; Vispute, R. D.; Viswanathan, R.; Godbole, V. P.; Ogale, S. B.

    In this report we report the effect of microstructural variations on sensing activity of SnO2 thin films. The tin oxide thin films are deposited by using the technique of pulsed laser ablation. The process parameters, i.e. oxygen partial pressure, are varied to obtain films with different stoichiometries and microstructures. Some of these films are bombarded with medium energy (140 keV) argon ions at various dose levels. Structural and compositional variations in the films have been studied by using low angle X-ray diffraction, Moessbauer spectroscopy and in-situ resistivity measurements while optical response has been monitored by using UV-visible spectroscopy. The films synthesized and processed under different conditions have been subjected to examination of gas and humidity sensing behavior.

  12. High sensitive formaldehyde graphene gas sensor modified by atomic layer deposition zinc oxide films

    SciTech Connect

    Mu, Haichuan; Zhang, Zhiqiang; Wang, Keke; Xie, Haifen; Zhao, Xiaojing; Liu, Feng

    2014-07-21

    Zinc oxide (ZnO) thin films with various thicknesses were fabricated by Atomic Layer Deposition on Chemical Vapor Deposition grown graphene films and their response to formaldehyde has been investigated. It was found that 0.5 nm ZnO films modified graphene sensors showed high response to formaldehyde with the resistance change up to 52% at the concentration of 9 parts-per-million (ppm) at room temperature. Meanwhile, the detection limit could reach 180 parts-per-billion (ppb) and fast response of 36 s was also obtained. The high sensitivity could be attributed to the combining effect from the highly reactive, top mounted ZnO thin films, and high conductive graphene base network. The dependence of ZnO films surface morphology and its sensitivity on the ZnO films thickness was also investigated.

  13. Evolution of microstructure in vanadium oxide bolometer film during annealing process

    NASA Astrophysics Data System (ADS)

    Su, Yu-Yu; Cheng, Xing-Wang; Li, Jing-Bo; Dou, Yan-Kun; Rehman, Fida; Su, De-Zhi; Jin, Hai-Bo

    2015-12-01

    Vanadium oxide thin films were prepared through direct current magnetron reactive sputtering and post annealing process. The evolution of composition, microstructure, and electrical properties of as-deposited amorphous films during the annealing process was clarified by X-ray diffraction, scanning electron microscopy and temperature-dependent resistance measurement. A new composition of thin film was acquired which consisted of crystalline V6O13 and amorphous phase. Sheet resistance and temperature coefficient of resistance (TCR) of the thin film are 90 kΩ/□ (measured at room temperature) and 2.52%/K, respectively. No metal-to-semiconductor transition was observed in the obtained film at temperatures ranging from room-temperature to 90 °C, suggesting the thin film is suitable for the application in microbolometer.

  14. Influence of Heat Treatment Conditions on the Properties of Vanadium Oxide Thin Films for Thermochromic Applications.

    PubMed

    Kim, Donguk; Kwon, Samyoung; Park, Young; Boo, Jin-Hyo; Nam, Sang-Hun; Joo, Yang Tae; Kim, Minha; Lee, Jaehyeong

    2016-05-01

    In present work, the effects of the heat treatment on the structural, optical, and thermochromic properties of vanadium oxide films were investigated. Vanadium dioxide (VO2) thin films were deposited on glass substrate by reactive pulsed DC magnetron sputtering from a vanadium metal target in mixture atmosphere of argon and oxygen gas. Various heat treatment conditions were applied in order to evaluate their influence on the crystal phases formed, surface morphology, and optical properties. The films were characterized by an X-ray diffraction (XRD) in order to investigate the crystal structure and identify the phase change as post-annealing temperature of 500-600 degrees C for 5 minutes. Surface conditions of the obtained VO2(M) films were analyzed by field emission scanning electron microscopy (FE-SEM) and the semiconductor-metal transition (SMT) characteristics of the VO2 films were evaluate by optical spectrophotometry in the UV-VIS-NIR, controlling temperature of the films.

  15. Electrophoretic deposition of polyacrylic acid and composite films containing nanotubes and oxide particles.

    PubMed

    Wang, Y; Deen, I; Zhitomirsky, I

    2011-10-15

    Electrophoretic deposition (EPD) method has been developed for the deposition of thin films of polyacrylic acid (PAA). This method allowed the formation of uniform films of controlled thickness on conductive substrates. It was shown that PAA can be used as a common dispersing agent suitable for charging and EPD of various materials, such as multiwalled carbon nanotubes, halloysite nanotubes, MnO(2), NiO, TiO(2) and SiO(2). The feasibility of EPD of composite films containing the nanotubes and oxide particles in a PAA matrix has been demonstrated. The kinetics of deposition and deposition mechanisms were investigated and discussed. The films were studied by thermogravimetric analysis, differential thermal analysis, X-ray diffraction and scanning electron microscopy. The results indicated that film thickness and composition can be varied. Obtained results pave the way for the fabrication of PAA and composite films for biomedical, electrochemical and other applications.

  16. Fabrication of transparent and ultraviolet shielding composite films based on graphene oxide and cellulose acetate.

    PubMed

    de Moraes, Ana Carolina Mazarin; Andrade, Patricia Fernanda; de Faria, Andreia Fonseca; Simões, Mateus Batista; Salomão, Francisco Carlos Carneiro Soares; Barros, Eduardo Bedê; Gonçalves, Maria do Carmo; Alves, Oswaldo Luiz

    2015-06-05

    Graphene oxide (GO) has been considered a promising filler material for building polymeric nanocomposites because of its excellent dispersibility and high surface area. In this work, we present the fabrication and characterization of transparent and ultraviolet (UV) shielding composite films based on GO and cellulose acetate (CA). GO sheets were found to be well-dispersed throughout the CA matrix, providing smooth and homogeneous composite films. Moreover, the GO sheets were completely embedded within the CA matrix and no presence of this nanomaterial was found at the surface. Nevertheless, CAGO composite films offered an improved high energy light-shielding capacity when compared to pristine CA films. Particularly for UVC irradiation, the CAGO film containing 0.50wt% GO displayed a UV-shielding capacity of 57%, combined with 79% optical transparency under visible light. These CAGO composite films can be potentially applied as transparent UV-protective coatings for packing biomedical, pharmaceutical, and food products.

  17. Parallel writing on zirconium nitride thin films by local oxidation nanolithography

    NASA Astrophysics Data System (ADS)

    Farkas, N.; Comer, J. R.; Zhang, G.; Evans, E. A.; Ramsier, R. D.; Wight, S.; Dagata, J. A.

    2004-12-01

    Parallel pattern transfer of submicrometer-scale oxide features onto zirconium nitride thin films is reported. The oxidation reaction was verified by Auger microprobe analysis and secondary ion mass spectrometry. Oxide features of ˜70nm in height can be formed and selectively etched in a dilute aqueous hydrogen fluoride solution. This provides an interesting route to potential new applications for high-melting point, biocompatible surfaces that possess small feature sizes with controlled geometries.

  18. Effect of negative bias on the composition and structure of the tungsten oxide thin films deposited by magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Wang, Meihan; Lei, Hao; Wen, Jiaxing; Long, Haibo; Sawada, Yutaka; Hoshi, Yoichi; Uchida, Takayuki; Hou, Zhaoxia

    2015-12-01

    Tungsten oxide thin films were deposited at room temperature under different negative bias voltages (Vb, 0 to -500 V) by DC reactive magnetron sputtering, and then the as-deposited films were annealed at 500 °C in air atmosphere. The crystal structure, surface morphology, chemical composition and transmittance of the tungsten oxide thin films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and UV-vis spectrophotometer. The XRD analysis reveals that the tungsten oxide films deposited at different negative bias voltages present a partly crystallized amorphous structure. All the films transfer from amorphous to crystalline (monoclinic + hexagonal) after annealing 3 h at 500 °C. Furthermore, the crystallized tungsten oxide films show different preferred orientation. The morphology of the tungsten oxide films deposited at different negative bias voltages is consisted of fine nanoscale grains. The grains grow up and conjunct with each other after annealing. The tungsten oxide films deposited at higher negative bias voltages after annealing show non-uniform special morphology. Substoichiometric tungsten oxide films were formed as evidenced by XPS spectra of W4f and O1s. As a result, semi-transparent films were obtained in the visible range for all films deposited at different negative bias voltages.

  19. Unexpected behaviour of one Pb monolayer deposited on aluminum oxide thin film grown on Ag(111)

    SciTech Connect

    Vizzini, Sébastien Bertoglio, M.; Oughaddou, Hamid; Hoarau, J. Y.; Biberian, J. P.; Aufray, B.

    2013-12-23

    Using scanning tunneling microscopy (STM), Auger electron spectroscopy, and low energy electron diffraction, we have observed a surprising complete dissolution at room temperature of one lead monolayer deposited by evaporation on an aluminum oxide thin film (∼0.8 nm thick) previously grown on Ag (111). We have observed the quasi-instantaneous diffusion of the lead deposit through the oxide layer to the silver/oxide interface. After the diffusion process, lead atoms form a Moiré superstructure, which is characterized by STM through the oxide layer. This unexpected behavior puts in light the very weak interaction between the aluminum oxide and the silver substrate.

  20. Two types of local oxide/substrate defects in very thin silicon dioxide films on silicon

    NASA Astrophysics Data System (ADS)

    Lau, W. S.; Sane, V.; Pey, K. S.; Cronquist, B.

    1995-11-01

    The local oxide defects observed in thin silicon dioxide films on p-type Si were studied with the electron beam induced current/tunneling current microscopy technique. Excluding pinholes, all the local defects observed are local oxide/substrate defects, i.e., local oxide defects propagated from defects in the Si substrate into the SiO2. It was observed that local oxide/substrate defects can be further differentiated into two different types by studying the transition from the true oxide electron beam induced current contrast to the tunneling current microscopy contrast.

  1. Physical properties in thin films of iron oxides.

    SciTech Connect

    Uribe, J. D.; Osorio, J.; Barrero, C. A.; Girata, D.; Morales, A. L.; Hoffmann, A.; Materials Science Division; Univ. de Antioquia

    2008-01-01

    We have grown hematite ({alpha}-Fe{sub 2}O{sub 3}) thin films on stainless steel substrates and magnetite (Fe{sub 3}O{sub 4}) thin films on (0 0 1)-Si single crystal substrates by a RF magnetron sputtering process. {alpha}-Fe{sub 2}O{sub 3} thin films were grown in an Ar atmosphere at substrate temperatures around 400 C, and Fe{sub 3}O{sub 4} thin films in an Ar/O{sub 2} reactive atmosphere at substrate temperatures around 500 C. Conversion electron Moessbauer (CEM) spectra of {alpha}-Fe{sub 2}O{sub 3} thin films exhibit values for hyperfine parameter characteristic of the hematite stoichiometric phase in the weak ferromagnetic state [R.E. Vandenberghe, in: Moessbauer Spectroscopy and Applications in Geology, University Gent, Belgium, 1990. [1

  2. Electrocatalytic Oxidation of Alcohols on Cu2O/Cu Thin Film Electrodeposited on Titanium Substrate

    NASA Astrophysics Data System (ADS)

    Bezghiche-Imloul, T.; Hammache-Makhloufi, H.; Ait Ahmed, N.

    2016-05-01

    A novel class of nanomaterials consisting of a composite thin film of cooper metal nanoparticles and cuprous oxide (Cu2O/Cu) for the catalytic electrooxidation of methanol, ethanol and ethylene glycol is considered here. The material was prepared by electrochemical deposition under a potentiostatic condition of -250mV vs saturated calomel electrode (SCE) from acetate bath at titanium substrate. The effect of electrodeposition time on the structure, composition and morphology of the deposit was investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results indicated the formation of pure cuprous oxide Cu2O thin film at low electrodeposition time (5 min) and Cu2O oxide thin film decorated with Cu nanoparticles (Cu2O/Cu) at high electrodeposition time. The obtained Cu2O and Cu2O/Cu thin films were explored for the electrochemical oxidation of alcohols in 1 M NaOH alkaline medium using cyclic voltammetry (CV) method. The Cu2O/Cu thin film grown at electrodeposition time of 15 min shows the best electrocatalytic performance toward ethanol oxidation. The effect of concentration of alcohols on the oxidation reaction was studied by CV and chronoamperometry. It was found that the reaction is governed by an irreversible diffusion process. The promising electrocatalytic activity of the Cu2O/Cu electrode provides a new platform for the fabrication of high-performance thin films for alcohols oxidation in alkaline medium. Therefore, the Cu2O/Cu electrode is a suitable as a less expensive electrocatalyst for alcohols oxidation.

  3. Evaluation of Characterization Techniques for Iron Pipe Corrosion Products and Iron Oxide Thin Films

    SciTech Connect

    Borch, Thomas; Camper, Anne K.; Biederman, Joel A.; Butterfield, Phillip; Gerlach, Robin; Amonette, James E.

    2008-10-01

    A common problem faced by drinking water studies is that of properly characterizing the corrosion products (CP) in iron pipescor synthetic Fe (hydr)oxides used to simulate the iron pipe used in municipal drinking-water systems. The present work compares the relative applicability of a suite of imaging and analytical techniques for the characterization of CPs and synthetic Fe oxide thin films and provide an overview of the type of data that each instrument can provide as well as their limitations to help researchers and consultants choose the best technique for a given task. Crushed CP from a water distribution system and synthetic Fe oxide thin films formed on glass surfaces were chosen as test samples for this evaluation. The CP and synthetic Fe oxide thin films were analyzed by atomic force microscopy (AFM), scanning electron microscopy (SEM), energy-dispersive spectroscopy, time-of-flight secondary ion mass spectrometry (ToF-SIMS), X-ray powder diffractometry (XRD), grazing incident diffractometry (GID), transmission electron microscopy (TEM), selected area electron diffraction, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared, Mössbauer spectroscopy, Brunauer-Emmett-Teller N2 adsorption and Fe concentration was determined by the ferrozine method. XRD and GID were found to be the most suitable techniques for identification of the mineralogical composition of CP and synthetic Fe oxide thin films, respectively. AFM and a combined ToF-SIMS-AFM approach proved excellent for roughness and depth profiling analysis of synthetic Fe oxide thin films, respectively. Corrosion products were difficult to study by AFM due to their surface roughness, while synthetic Fe oxide thin films resisted most spectroscopic methods due to their limited thickness (118 nm). XPS analysis is not recommended for mixtures of Fe (hydr)oxides due to their spectral similarities. SEM and TEM provided great detail on mineralogical morphology.

  4. Stability of passivated 316L stainless steel oxide films for cardiovascular stents.

    PubMed

    Shih, Chun-Che; Shih, Chun-Ming; Chou, Kuang-Yi; Lin, Shing-Jong; Su, Yea-Yang

    2007-03-15

    Passivated 316L stainless steel is used extensively in cardiovascular stents. The degree of chloride ion attack might increase as the oxide film on the implant degrades from exposure to physiological fluid. Stability of 316L stainless steel stent is a function of the concentration of hydrated and hydrolyated oxide concentration inside the passivated film. A high concentration of hydrated and hydrolyated oxide inside the passivated oxide film is required to maintain the integrity of the passivated oxide film, reduce the chance of chloride ion attack, and prevent any possible leaching of positively charged ions into the surrounding tissue that accelerate the inflammatory process. Leaching of metallic ions from corroded implant surface into surrounding tissue was confirmed by the X-ray mapping technique. The degree of thrombi weight percentage [W(ao): (2.1 +/- 0.9)%; W(ep): (12.5 +/- 4.9)%, p < 0.01] between the amorphous oxide (AO) and the electropolishing (EP) treatment groups was statistically significant in ex-vivo extracorporeal thrombosis experiment of mongrel dog. The thickness of neointima (T(ao): 100 +/- 20 microm; T(ep): 500 +/- 150 microm, p < 0.01) and the area ratio of intimal response at 4 weeks (AR(ao): 0.62 +/- 0.22; AR(ep): 1.15 +/- 0.42, p < 0.001) on the implanted iliac stents of New Zealand rabbit could be a function of the oxide properties.

  5. High Stability Performance of Quinary Indium Gallium Zinc Aluminum Oxide Films and Thin-Film Transistors Deposited Using Vapor Cooling Condensation Method

    NASA Astrophysics Data System (ADS)

    Lin, Yung-Hao; Lee, Ching-Ting

    2017-08-01

    High-quality indium gallium zinc aluminum oxide (IGZAO) thin films with various Al contents have been deposited using the vapor cooling condensation method. The electron mobility of the IGZAO films was improved by 89.4% on adding Al cation to IGZO film. The change in the electron concentration and mobility of the IGZAO films was 7.3% and 7.0%, respectively, when the temperature was changed from 300 K to 225 K. These experimental results confirm the high performance and stability of the IGZAO films. The performance stability mechanisms of IGZAO thin-film transistors (TFTs) were investigated in comparison with IGZO TFTs.

  6. Nickel oxide thin film from electrodeposited nickel sulfide thin film: peroxide sensing and photo-decomposition of phenol.

    PubMed

    Jana, Sumanta; Samai, Subhasis; Mitra, Bibhas C; Bera, Pulakesh; Mondal, Anup

    2014-09-14

    A novel non-enzymatic peroxide sensor has been constructed by using nickel oxide (NiO) thin films as sensing material, which were prepared by a two-step process: (i) electrodeposition of nickel sulfide (NiS) and (ii) thermal air oxidation of as-deposited NiS to NiO. The resultant material is highly porous and comprises interconnected nanofibers. UV-Vis spectroscopy, FTIR spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM) were used for a complete characterization of nanostructured NiO thin films. Cyclic voltammetry study shows that NiO/ITO electrode facilitates the oxidation of hydrogen peroxide and exhibits excellent catalytic activity towards its sensing. The amperometric study of NiO/ITO was carried out to determine the sensitivity, linear range, detection limit of the proposed sensor. The sensor exhibits prominent electrocatalytic activity toward the oxidation of H2O2 with a wide linear range and a low detection limit. The possible use of the synthesized NiO thin films as an effective photocatalyst for the decomposition of phenol is also discussed.

  7. Anodic luminescence, structural, photoluminescent, and photocatalytic properties of anodic oxide films grown on niobium in phosphoric acid

    NASA Astrophysics Data System (ADS)

    Stojadinović, Stevan; Tadić, Nenad; Radić, Nenad; Stefanov, Plamen; Grbić, Boško; Vasilić, Rastko

    2015-11-01

    This article reports on properties of oxide films obtained by anodization of niobium in phosphoric acid before and after the dielectric breakdown. Weak anodic luminescence of barrier oxide films formed during the anodization of niobium is correlated to the existence of morphological defects in the oxide layer. Small sized sparks generated by dielectric breakdown of formed oxide film cause rapid increase of luminescence intensity. The luminescence spectrum of obtained films on niobium under spark discharging is composed of continuum radiation and spectral lines caused by electronic spark discharging transitions in oxygen and hydrogen atoms. Oxide films formed before the breakdown are amorphous, while after the breakdown oxide films are partly crystalline and mainly composed of Nb2O5 hexagonal phase. The photocatalytic activity of obtained oxide films after the breakdown was investigated by monitoring the degradation of methyl orange. Increase of the photocatalytic activity with time is related to an increase of oxygen vacancy defects in oxide films formed during the process. Also, higher concentration of oxygen vacancy defects in oxide films results in higher photoluminescence intensity.

  8. Effect of the lead oxide content on the microstructure and properties of PZT films obtained by RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Mukhin, N. V.; Chigirev, D. A.

    2017-07-01

    Experimental studies of the influence of lead oxide as well as temperature and time of heat treatment on the microstructure and ferroelectric properties of PZT films obtained by the high-frequency magnetron sputtering method were carried out. It is shown that the change in the ferroelectric properties of polycrystalline PZT films can be explained by their heterophase structure with inclusions of lead oxide. It was found that the presence of a sublayer of lead oxide leads to a self-polarization of the film of the PZT. During the formation of the perovskite structure, the diffusion of lead oxide to the surface of the film occurs more intensively than after its formation.

  9. Effects of sputtering power on properties of copper oxides thin films deposited on glass substrates

    SciTech Connect

    Ooi, P. K.; Ng, S. S.; Abdullah, M. J.

    2015-04-24

    Copper oxides are deposited by radio frequency sputtering using copper target in the mixture of argon and oxygen gasses. The structural and optical properties of the copper oxides deposited at different sputtering powers have been investigated. All the films are single phase polycrystalline. At low RF power (100 W), the film is monoclinic structure of cupric oxide (CuO). Meanwhile, the films are cubic structure of cuprous oxide (Cu2O) at higher RF power. Field emission scanning electron microscopy images show the films have different morphologies with small grain size and consist of a lot of voids. The analysis of energy dispersive X-ray spectroscopy shows that the ratio of Cu to O is increased as the RF power increased. From the ultraviolet–visible spectroscopy, the films have a broad absorption edge in the range of 300–500 nm. The band gap of the films grown at RF power of 100 W, and 120 W and above, were 1.18 eV and 2.16 eV, respectively.

  10. Oxidation of the Ru(0001) surface covered by weakly bound, ultrathin silicate films

    DOE PAGES

    Emmez, Emre; Anibal Boscoboinik, J.; Tenney, Samuel; ...

    2015-06-30

    Bilayer silicate films grown on metal substrates are weakly bound to the metal surfaces, which allows ambient gas molecules to intercalate the oxide/metal interface. In this work, we studied the interaction of oxygen with Ru(0001) supported ultrathin silicate and aluminosilicate films at elevated O2 pressures (10-5–10 mbar) and temperatures (450–923 K). The results show that the silicate films stay essentially intact under these conditions, and oxygen in the film does not exchange with oxygen in the ambient. O2 molecules readily penetrate the film and dissociate on the underlying Ru surface underneath. Also, the silicate layer does however strongly passivate themore » Ru surface towards RuO2(110) oxide formation that readily occurs on bare Ru(0001) under the same conditions. Lastly, the results indicate considerable spatial effects for oxidation reactions on metal surfaces in the confined space at the interface. Moreover, the aluminosilicate films completely suppress the Ru oxidation, providing some rationale for using crystalline aluminosilicates in anti-corrosion coatings.« less

  11. Transparent ferromagnetic and semiconducting behavior in Fe-Dy-Tb based amorphous oxide films

    PubMed Central

    Taz, H.; Sakthivel, T.; Yamoah, N. K.; Carr, C.; Kumar, D.; Seal, S.; Kalyanaraman, R.

    2016-01-01

    We report a class of amorphous thin film material comprising of transition (Fe) and Lanthanide metals (Dy and Tb) that show unique combination of functional properties. Films were deposited with different atomic weight ratio (R) of Fe to Lanthanide (Dy + Tb) using electron beam co-evaporation at room temperature. The films were found to be amorphous, with grazing incidence x-ray diffraction and x-ray photoelectron spectroscopy studies indicating that the films were largely oxidized with a majority of the metal being in higher oxidation states. Films with R = 0.6 were semiconducting with visible light transmission due to a direct optical band-gap (2.49 eV), had low resistivity and sheet resistance (7.15 × 10−4 Ω-cm and ~200 Ω/sq respectively), and showed room temperature ferromagnetism. A metal to semiconductor transition with composition (for R < 11.9) also correlated well with the absence of any metallic Fe0 oxidation state in the R = 0.6 case as well as a significantly higher fraction of oxidized Dy. The combination of amorphous microstructure and room temperature electronic and magnetic properties could lead to the use of the material in multiple applications, including as a transparent conductor, active material in thin film transistors for display devices, and in spin-dependent electronics. PMID:27298196

  12. Oxidation of the Ru(0001) surface covered by weakly bound, ultrathin silicate films

    SciTech Connect

    Emmez, Emre; Anibal Boscoboinik, J.; Tenney, Samuel; Sutter, Peter; Shaikhutdinov, Shamil; Freund, Hans-Joachim

    2015-06-30

    Bilayer silicate films grown on metal substrates are weakly bound to the metal surfaces, which allows ambient gas molecules to intercalate the oxide/metal interface. In this work, we studied the interaction of oxygen with Ru(0001) supported ultrathin silicate and aluminosilicate films at elevated O2 pressures (10-5–10 mbar) and temperatures (450–923 K). The results show that the silicate films stay essentially intact under these conditions, and oxygen in the film does not exchange with oxygen in the ambient. O2 molecules readily penetrate the film and dissociate on the underlying Ru surface underneath. Also, the silicate layer does however strongly passivate the Ru surface towards RuO2(110) oxide formation that readily occurs on bare Ru(0001) under the same conditions. Lastly, the results indicate considerable spatial effects for oxidation reactions on metal surfaces in the confined space at the interface. Moreover, the aluminosilicate films completely suppress the Ru oxidation, providing some rationale for using crystalline aluminosilicates in anti-corrosion coatings.

  13. Preparation of bioactive titania films on titanium metal via anodic oxidation.

    PubMed

    Cui, X; Kim, H-M; Kawashita, M; Wang, L; Xiong, T; Kokubo, T; Nakamura, T

    2009-01-01

    To research the crystal structure and surface morphology of anodic films on titanium metal in different electrolytes under various electrochemical conditions and investigate the effect of the crystal structure of the oxide films on apatite-forming ability in simulated body fluid (SBF). Titanium oxide films were prepared using an anodic oxidation method on the surface of titanium metal in four different electrolytes: sulfuric acid, acetic acid, phosphoric acid and sodium sulfate solutions with different voltages for 1 min at room temperature. Anodic films that consisted of rutile and/or anatase phases with porous structures were formed on titanium metal after anodizing in H(2)SO(4) and Na(2)SO(4) electrolytes, while amorphous titania films were produced after anodizing in CH(3)COOH and H(3)PO(4) electrolytes. Titanium metal with the anatase and/or rutile crystal structure films showed excellent apatite-forming ability and produced a compact apatite layer covering all the surface of titanium after soaking in SBF for 7d, but titanium metal with amorphous titania layers was not able to induce apatite formation. The resultant apatite layer formed on titanium metal in SBF could enhance the bonding strength between living tissue and the implant. Anodic oxidation is believed to be an effective method for preparing bioactive titanium metal as an artificial bone substitute even under load-bearing conditions.

  14. Transparent ferromagnetic and semiconducting behavior in Fe-Dy-Tb based amorphous oxide films

    NASA Astrophysics Data System (ADS)

    Taz, H.; Sakthivel, T.; Yamoah, N. K.; Carr, C.; Kumar, D.; Seal, S.; Kalyanaraman, R.

    2016-06-01

    We report a class of amorphous thin film material comprising of transition (Fe) and Lanthanide metals (Dy and Tb) that show unique combination of functional properties. Films were deposited with different atomic weight ratio (R) of Fe to Lanthanide (Dy + Tb) using electron beam co-evaporation at room temperature. The films were found to be amorphous, with grazing incidence x-ray diffraction and x-ray photoelectron spectroscopy studies indicating that the films were largely oxidized with a majority of the metal being in higher oxidation states. Films with R = 0.6 were semiconducting with visible light transmission due to a direct optical band-gap (2.49 eV), had low resistivity and sheet resistance (7.15 × 10‑4 Ω-cm and ~200 Ω/sq respectively), and showed room temperature ferromagnetism. A metal to semiconductor transition with composition (for R < 11.9) also correlated well with the absence of any metallic Fe0 oxidation state in the R = 0.6 case as well as a significantly higher fraction of oxidized Dy. The combination of amorphous microstructure and room temperature electronic and magnetic properties could lead to the use of the material in multiple applications, including as a transparent conductor, active material in thin film transistors for display devices, and in spin-dependent electronics.

  15. Influences of the main anodic electroplating parameters on cerium oxide films

    NASA Astrophysics Data System (ADS)

    Yang, Yang; Yang, Yumeng; Du, Xiaoqing; Chen, Yu; Zhang, Zhao; Zhang, Jianqing

    2014-06-01

    Cerium oxide thin films were fabricated onto 316 L stainless steel via a potentiostatically anodic electrodeposition approach in the solutions containing cerium(III) nitrate (0.05 M), ammonia acetate (0.1 M) and ethanol (10% V/V). The electrochemical behaviors and deposition parameters (applied potential, bath temperature, dissolving O2 and bath pH) have been investigated. Results show that, the electrochemical oxidation of Ce3+ goes through one electrochemical step, which is under charge transfer control. The optimum applied potential for film deposition is 0.8 V. Bath temperature plays a significant effect on the deposition rate, composition (different colors of the film) and surface morphology of the deposits. Due to the hydrolysis of Ce3+, cerous hydroxide is facility to form when the bath temperature is higher than 60 °C. The electroplating bath pH is another key role for the anodic deposition of cerium oxide thin films, and the best bath pH is around 6.20. N2 or O2 purged into the bath will result in film porosities and O2 favors cerium oxide particles and film generation.

  16. Optical, structural and electrochromic properties of sputter- deposited W-Mo oxide thin films

    NASA Astrophysics Data System (ADS)

    Gesheva, K.; Arvizu, M. A.; Bodurov, G.; Ivanova, T.; Niklasson, G. A.; Iliev, M.; Vlakhov, T.; Terzijska, P.; Popkirov, G.; Abrashev, M.; Boyadjiev, S.; Jágerszki, G.; Szilágyi, I. M.; Marinov, Y.

    2016-10-01

    Thin metal oxide films were investigated by a series of characterization techniques including impedance spectroscopy, spectroscopic ellipsometry, Raman spectroscopy, and Atomic Force Microscopy. Thin film deposition by reactive DC magnetron sputtering was performed at the Ångström Laboratory. W and Mo targets (5 cm diameter) and various oxygen gas flows were employed to prepare samples with different properties, whereas the gas pressure was kept constant at about 30 mTorr. The substrates were 5×5 cm2 plates of unheated glass pre-coated with ITO having a resistance of 40 ohm/sq. Film thicknesses were around 300 nm as determined by surface profilometry. Newly acquired equipment was used to study optical spectra, optoelectronic properties, and film structure. Films of WO3 and of mixed W- Mo oxide with three compositions showed coloring and bleaching under the application of a small voltage. Cyclic voltammograms were recorded with a scan rate of 5 mV s-1. Ellipsometric data for the optical constants show dependence on the amount of MoOx in the chemical composition. Single MoOx film, and the mixed one with only 8% MoOx have the highest value of refractive index, and similar dispersion in the visible spectral range. Raman spectra displayed strong lines at wavenumbers between 780 cm-1 and 950 cm-1 related to stretching vibrations of WO3, and MoO3. AFM gave evidence for domains of different composition in mixed W-Mo oxide films.

  17. Optimization of Dimensionless Figure of Merit in Oxide Thin Film Thermoelectrics

    NASA Astrophysics Data System (ADS)

    Osborne, Daniel; Huxtable, Scott; Tiwari, Ashutosh; Abiade, Jeremiah

    2010-03-01

    The ability of uniquely functional thermoelectric materials to convert waste heat directly into electricity is critical considering the global energy economy. Profitable, energy-efficient thermoelectrics possess thermoelectric figures of merit ZT >= 1. We examined the effect of metal nanoparticle -- oxide film interfaces on the thermal conductivity κ and Seebeck coefficient S in bilayer and multilayer thin film oxide thermoelectrics in an effort to improve the dimensionless figure of merit ZT. Since a thermoelectric's figure of merit ZT is directly proportional to S/κ, reducing κ and increasing S are key strategies to optimize ZT. We reduced κ by phonon scattering due to the inclusion of metal nanoparticles in the bulk of the thermoelectric thin film, and increased S due to energy-dependent electron scattering at the metal - oxide interfaces. Doped strontium titanate (STO) thin film/Au nanoparticle composites were synthesized by alternate ablation of Au and Nb-doped STO targets during pulsed laser deposition. Characterization of the thermoelectric films involve XRD, XPS, and TEM analyses, Seebeck coefficient measurements, and also measurements of the thermal conductivity via time-domain thermoreflectance. The measured thermal conductivities and Seebeck coefficients of the thin films shows a strong dependence on the nanoscale interfaces of the films.

  18. Retardation of lipid oxidation using gelatin film incorporated with longan seed extract compared with BHT.

    PubMed

    Sai-Ut, Samart; Benjakul, Soottawat; Rawdkuen, Saroat

    2015-09-01

    The aim of the present work was to apply the gelatin films with different levels of longan seed extract (LS) or butylated hydroxytoluene (BHT) on retardation of lipid oxidation in soybean oil. The films incorporated with various concentrations of aqueous LS (0, 50, 100, 300, and 500 ppm) or BHT (50, and 100 ppm) were developed. The films had transmittance percentages of 60-80 % at 570 nm and showed good light barrier properties when the concentration of LS or BHT increased. About 97 % protein solubility and 41 to 54 % water solubility were obtained for the developed films. Antioxidative activity of gelatin films incorporated with LS increased markedly with increasing storage time as indicated by the increase in DPPH radical scavenging activity (41-50 %) (P < 0.05). Films incorporated with LS or BHT showed the preventive effect on lipid oxidation of soybean oil during 30 days of storage. At the level of 500 ppm, LS provided the highest efficacy for lipid oxidation retardation as evidenced by lower conjugated diene (CD) values (P > 0.05). According to these findings, gelatin film incorporated with longan seed extract or BHT could be used as a tool to prolong the shelf-life of oily foods.

  19. Structure, stability and electrochromic properties of polyaniline film covalently bonded to indium tin oxide substrate

    NASA Astrophysics Data System (ADS)

    Zhang, Wenzhi; Ju, Wenxing; Wu, Xinming; Wang, Yan; Wang, Qiguan; Zhou, Hongwei; Wang, Sumin; Hu, Chenglong

    2016-03-01

    Indium tin oxide (ITO) substrate was modified with 4-aminobenzylphosphonic acid (ABPA), and then the polyaniline (PANI) film covalently bonded to ITO substrate was prepared by the chemical oxidation polymerization. X-ray photoelectron spectroscopy (XPS), attenuated total reflection infrared (ATR-IR) spectroscopy, and atomic force microscopy (AFM) measurements demonstrated that chemical binding was formed between PANI and ABPA-modified ITO surface, and the maximum thickness of PANI layer is about 30 nm. The adhesive strength of PANI film on ITO substrate was tested by sonication. It was found that the film formed on the modified ITO exhibited a much better stability than that on bare one. Cyclic voltammetry (CV) and UV-vis spectroscopy measurements indicated that the oxidative potentials of PANI film on ABPA-modified ITO substrate were decreased and the film exhibited high electrochemical activities. Moreover, the optical contrast increased from 0.58 for PANI film (without ultrasound) to 1.06 for PANI film (after ultrasound for 60 min), which had an over 83% enhancement. The coloration time was 20.8 s, while the bleaching time was 19.5 s. The increase of electrochromic switching time was due to the lower ion diffusion coefficient of the large cation of (C4H9)4N+ under the positive and negative potentials as comparison with the small Li+ ion.

  20. Structure and properties of uranium oxide thin films deposited by pulsed dc magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Lin, Jianliang; Dahan, Isaac; Valderrama, Billy; Manuel, Michele V.

    2014-05-01

    Crystalline uranium oxide thin films were deposited in an unbalanced magnetron sputtering system by sputtering from a depleted uranium target in an Ar + O2 mixture using middle frequency pulsed dc magnetron sputtering. The substrate temperature was constantly maintained at 500 °C. Different uranium oxide phases (including UO2-x, UO2, U3O7 and U3O8) were obtained by controlling the percentage of the O2 flow rate to the total gas flow rate (f) in the chamber. The crystal structure of the films was characterized using X-ray diffraction and the microstructure of the films was studied using transmission electron microscopy and atom probe tomography. When the f was below 10%, the film contains a mixture of metallic uranium and UO2-x phases. As the f was controlled in the range of 10-13%, UO2 films with a (2 2 0) preferential orientation were obtained. The oxide phase rapidly changed to a mixture of U3O7 and U3O8 as the f was increased to the range of 15-18%. Further increasing the f to 20% and above, polycrystalline U3O8 thin films with a (0 0 1) preferential orientation were formed. The hardness and Young's modulus of the uranium oxide films were evaluated using nanoindentation. The film containing a single UO2 phase exhibited the maximum hardness of 14.3 GPa and a Young's modulus of 195 GPa. The UO2 thin film also exhibited good thermal stability in that no phase change was observed after annealing at 600 °C in vacuum for 104 h.

  1. Fabrication of biocompatible and mechanically reinforced graphene oxide-chitosan nanocomposite films

    PubMed Central

    2013-01-01

    Background Graphene oxide (GO)can be dispersed through functionalization, or chemically converted to make different graphene-based nanocomposites with excellent mechanical and thermal properties. Chitosan, a partially deacetylated derivative of chitin, is extensively used for food packaging, biosensors, water treatment, and drug delivery. GO can be evenly dispersed in chitosan matrix through the formation of amide linkages between them, which is different from previous reports focusing on preparing GO/chitosan nanocomposites through physical mixing. Results In this study, free-standing graphene oxide-chitosan (GO-chitosan) nanocomposite films have been prepared. The GO-chitosan films are biologically compatible and mechanically reinforced. Through the formation of amide linkages between GO’s carboxylic acid groups and chitosan's amine groups, GO could be evenly dispersed within the chitosan matrix. We also characterized the GO-chitosan composite films using element analysis, Fourier transform infrared spectroscopy, X-ray photo electron spectroscopy, differential scanning calorimetry, and thermo gravimetric analysis. Compared to pristine chitosan film, the tensile strength of GO-chitosan film is improved by 2.5 folds and Young’s modulus increases by nearly 4.6 folds. The glass transition temperature of GO-chitosan composite film shifts from 118°C to 158°C compared to the pristine chitosan, indicating its enhanced thermal stability. GO-chitosan composite film was also evaluated for its biocompatibility with C3H10T1/2 cells by in vitro fluorescent staining. The graphene oxide-reinforced chitosan composite films could have applications in functional biomaterials. Conclusion The present study describes a useful and simple method to chemically attach biocompatible chitosan onto graphene oxide. We envision that the GO-chitosan film will open avenues for next-generation graphene applications in the realm of functional biomaterial. PMID:23442350

  2. Post-Deposition Induced Conductivity in Pulsed Laser Irradiated Metal Doped Zinc Oxide Films

    SciTech Connect

    Wang, Lisa J; Exarhos, Gregory J

    2009-12-03

    The optical and electrical properties of doped solution-deposited and rf sputter-deposited thin metal oxide films were investigated following post deposition pulsed laser irradiation. Solution deposited films were annealed at 450 ºC. Following the heating regiment, the transparent metal oxide films were subjected to 355 nm pulsed Nd:YAG laser irradiation (4 nsec pulsewidth) at fluences between 5 and 150 mJ/cm2. Irradiation times at pulse frequencies of 30 Hz ranged from seconds to tens of minutes. Film densification, index change and a marked increase in conductivity were observed following irradiation in air and under vacuum of Al:ZnO (AZO), Ga:ZnO (GZO), and In:ZnO (IZO) films deposited on silica substrates. Despite the measured increase in conductivity, all films continued to show high transparency on the order of 90% at wavelengths from the band edge well into the near infrared region of the spectrum. Laser energies required for turning on the conductivity of these films varied depending upon the dopant. Irradiations in air yielded resistivity measurements on the order of 16.cm. Resistivities of films irradiated under vacuum were on the order of 0.1.cm. The increase in conductivity can be attributed to the formation of oxygen vacancies and subsequent promotion of free carriers into the conduction band. All irradiated films become insulating after around 24 hours. Oxygen atoms in air become reduced by electrons in the metal conduction band and diffuse into the vacancies in the lattice. The rate of this reduction process depends on the type of dopant. This work also sheds light on the damage threshold, correlating the optical properties with the presence of free carriers that have been introduced into the conduction band. All films were characterized by means of UV-VIS-NIR transmission spectroscopy, visible and UV Raman spectroscopy and Hall measurements. Analysis of interference fringes in measured transmission spectra allowed film density and refractive index

  3. Characterization of Antimicrobial Poly (Lactic Acid)/Nano-Composite Films with Silver and Zinc Oxide Nanoparticles.

    PubMed

    Chu, Zhuangzhuang; Zhao, Tianrui; Li, Lin; Fan, Jian; Qin, Yuyue

    2017-06-16

    Antimicrobial active films based on poly (lactic acid) (PLA) were prepared with nano-silver (nano-Ag) and nano-zinc oxide (nano-ZnO) using a solvent volatilizing method. The films were characterized for mechanical, structural, thermal, physical and antimicrobial properties. Scanning electron microscopy (SEM) images characterized the fracture morphology of the films with different contents of nano-Ag and nano-ZnO. The addition of nanoparticles into the pure PLA film decreased the tensile strength and elasticity modulus and increased the elongation of breaks-in other words, the flexibility and extensibility of these composites improved. According to the results of differential scanning calorimetry (DSC), the glass transition temperature of the PLA nano-composite films decreased, and the crystallinity of these films increased; a similar result was apparent from X-ray diffraction (XRD) analysis. The water vapor permeability (WVP) and opacity of the PLA nano-composite films augmented compared with pure PLA film. Incorporation of nanoparticles to the PLA films significantly improved the antimicrobial activity to inhibit the growth of Escherichia coli. The results indicated that PLA films with nanoparticles could be considered a potential environmental-friendly packaging material.

  4. Laser patterning of very thin indium tin oxide thin films on PET substrates

    NASA Astrophysics Data System (ADS)

    McDonnell, C.; Milne, D.; Prieto, C.; Chan, H.; Rostohar, D.; O'Connor, G. M.

    2015-12-01

    This work investigates the film removal properties of 30 nm thick Indium Tin Oxide (ITO) thin films, on flexible polyethylene terephthalate (PET) substrates, using 355, 532 and 1064 nm nanosecond pulses (ns), and 343 and 1064 nm femtosecond pulses. The ablation threshold was found to be dependent on the applied wavelength and pulse duration. The surface topography of the laser induced features were examined using atomic force microscopy across the range of wavelengths and pulse durations. The peak temperature, strain and stress tensors were examined in the film and substrate during laser heating, using finite element computational methods. Selective removal of the thin ITO film from the polymer substrate is possible at all wavelengths except at 266 nm, were damage to substrate is observed. The damage to the substrate results in periodic surface structures (LIPPS) on the exposed PET, with a period of twice the incident wavelength. Fragmented crater edges are observed at all nanosecond pulse durations. Film removal using 1030 nm femtosecond pulses results in clean crater edges, however, minor 5 nm damage to the substrate is also observed. The key results show that film removal for ITO on PET, is through film de-lamination across all wavelengths and pulse durations. Film de-lamination occurs due to thermo-elastic stress at the film substrate interface region, as the polymer substrate expands under heating from direct laser absorption and heat conduction across the film substrate interface.

  5. Study on the Preparation and Properties of Colored Iron Oxide Thin Films

    NASA Astrophysics Data System (ADS)

    Zhao, Xianhui; Li, Changhong; Liu, Qiuping; Duan, Yandong; He, Junjing; Liu, Su; Wang, Hai; Liang, Song

    2013-03-01

    Colored iron oxide thin films were prepared using Sol-gel technique. The raw materials were tetraethyl orthosilicate (TEOS), etoh ehanol (EtOH), iron nitrate, and de-ionized water. Various properties were measured and analysed, including the colour of thin films, surface topography, UV-Visible spectra, corrosion resistance and hydrophobicity. To understand how these properties influenced the structural and optical properties of Fe2O3 thin films, Scanning Electron Microscope (SEM), UV Spectrophotometer and other facilities were employed. Many parameters influence the performance of thin films, such as film layers, added H2O content, and the amount of polydimethylsiloxane (PDMS). When the volume ratio of TEOS, EtOH and H2O was 15: 13: 1, the quality of Fe(NO3)3·9H2O was 6g, and pH value was 3, reddish and uniform Fe2O3 thin films with excellent properties were produced. Obtained thin films possessed corrosion resistance in hydrochloric acid with pH=l and the absorption edge wavelength was ~350.2nm. Different H2O contents could result in different morphologies of Fe2O3 nanoparticles. When 1.5 ml PDMS was added into the Sol, thin films possessed hydrophobiliry without dropping. Coating with different layers, thin films appeared different morphologies. Meanwhile, with the increment of film layers, the absorbance increased gradually.

  6. Characterization of Antimicrobial Poly (Lactic Acid)/Nano-Composite Films with Silver and Zinc Oxide Nanoparticles

    PubMed Central

    Chu, Zhuangzhuang; Zhao, Tianrui; Li, Lin; Fan, Jian; Qin, Yuyue

    2017-01-01

    Antimicrobial active films based on poly (lactic acid) (PLA) were prepared with nano-silver (nano-Ag) and nano-zinc oxide (nano-ZnO) using a solvent volatilizing method. The films were characterized for mechanical, structural, thermal, physical and antimicrobial properties. Scanning electron microscopy (SEM) images characterized the fracture morphology of the films with different contents of nano-Ag and nano-ZnO. The addition of nanoparticles into the pure PLA film decreased the tensile strength and elasticity modulus and increased the elongation of breaks—in other words, the flexibility and extensibility of these composites improved. According to the results of differential scanning calorimetry (DSC), the glass transition temperature of the PLA nano-composite films decreased, and the crystallinity of these films increased; a similar result was apparent from X-ray diffraction (XRD) analysis. The water vapor permeability (WVP) and opacity of the PLA nano-composite films augmented compared with pure PLA film. Incorporation of nanoparticles to the PLA films significantly improved the antimicrobial activity to inhibit the growth of Escherichia coli. The results indicated that PLA films with nanoparticles could be considered a potential environmental-friendly packaging material. PMID:28773018

  7. Surface morphology of ultrathin graphene oxide films obtained by the SAW atomization

    NASA Astrophysics Data System (ADS)

    Balachova, Olga V.; Balashov, Sergey M.; Costa, Carlos A. R.; Pavani Filho, A.

    2015-08-01

    Lately, graphene oxide (GO) thin films have attracted much attention: they can be used as humidity-sensitive coatings in the surface acoustic wave (SAW) sensors; being functionalized, they can be used in optoelectronic or biodevices, etc. In this research we study surface morphology of small-area thin GO films obtained on Si and quartz substrates by deposition of very small amounts of H2O-GO aerosols produced by the SAW atomizer. An important feature of this method is the ability to work with submicrovolumes of liquids during deposition that provides relatively good control over the film thickness and quality, in particular, minimization of the coffee ring effect. The obtained films were examined using AFM and electron microscopy. Image analysis showed that the films consist of GO sheets of different geometry and sizes and may form discrete or continuous coatings at the surface of the substrates with the minimum thickness of 1.0-1.8 nm which corresponds to one or two monolayers of GO. The thickness and quality of the deposited films depend on the parameters of the SAW atomization (number of atomized droplets, a volume of the initial droplet, etc.) and on sample surface preparation (activation in oxygen plasma). We discuss the structure of the obtained films, uniformity and the surface coverage as a function of parameters of the film deposition process and sample preparation. Qualitative analysis of adhesion of GO films is made by rinsing the samples in DI water and subsequent evaluation of morphology of the remained films.

  8. Fluorination of epitaxial oxides: Creating ferrite and nickelate oxyfluoride films

    NASA Astrophysics Data System (ADS)

    May, Steven; Moon, Eun; Xie, Yujun; Keavney, David; Goebel, Justin; Laird, Eric; Li, Christopher

    2013-03-01

    In ABO3 perovskites, the physical properties are directly coupled to the nominal valence state of the B-site cation. In epitaxial thin films, the dominant strategy to control B-site valence is through the selection of a di- or trivalent cation on the A-site. However, this approach is limited, particularly when electron doping on the B-site is desired. Here we report a simple method for realizing oxyfluoride films, where the substitution of F for O is expected to reduce the B-site valence, providing a new means to tune electronic, optical and magnetic properties in thin films. Fluorination is achieved by spin coating an oxygen deficient film with poly(vinylidene fluoride). The film/polymer bilayer is then annealed, promoting the diffusion of F into the film. We have used this method to synthesize SrFeO3-δFδ and LaNiO3-δFδ (δ ? 0.5) films, as confirmed by x-ray photoemission spectroscopy and x-ray absorption spectroscopy. This work is supported by the U. S. Army Research Office under grant number W911NF-12-1-0132. Work at the Advanced Photon Source is supported by the U.S. Department of Energy (DOE), Office of Basic Energy Sciences under contract DE-AC02-06CH11357.

  9. Electrodeposition and electrochemical reduction of epitaxial metal oxide thin films and superlattices

    NASA Astrophysics Data System (ADS)

    He, Zhen

    The focus of this dissertation is the electrodeposition and electrochemical reduction of epitaxial metal oxide thin films and superlattices. The electrochemical reduction of metal oxides to metals has been studied for decades as an alternative to pyrometallurgical processes for the metallurgy industry. However, the previous work was conducted on bulk polycrystalline metal oxides. Paper I in this dissertation shows that epitaxial face-centered cubic magnetite (Fe3O4 ) thin films can be electrochemically reduced to epitaxial body-centered cubic iron (Fe) thin films in aqueous solution on single-crystalline Au substrates at room temperature. This technique opens new possibilities to produce special epitaxial metal/metal oxide heterojunctions and a wide range of epitaxial metallic alloy films from the corresponding mixed metal oxides. Electrodeposition, like biomineralization, is a soft solution processing method which can produce functional materials with special properties onto conducting or semiconducting solid surfaces. Paper II in this dissertation presents the electrodeposition of cobalt-substituted magnetite (CoxFe3-xO4, 0 of cobalt-substituted magnetite (CoxFe3-xO4, 0films and superlattices on Au single-crystalline substrates, which can be potentially used in spintronics and memory devices. Paper III in this dissertation reports the electrodeposition of crystalline cobalt oxide (Co3O4) thin films on stainless steel and Au single-crystalline substrates. The crystalline Co3O4 thin films exhibit high catalytic activity towards the oxygen evolution reaction in an alkaline solution. A possible application of the electrodeposited Co 3O4 is the fabrication of highly active and low-cost photoanodes for photoelectrochemical water-splitting cells.

  10. Preparation and Optical Properties of Zirconium-Titanium-Oxide Thin Films by Reactive Sputtering

    NASA Astrophysics Data System (ADS)

    Matsumoto, Hironaga; Sekine, Masato; Miura, Noboru; Nakano, Ryotaro; Matsumoto, Setsuko

    2005-02-01

    Zirconium-titanium-oxide thin films were prepared by multi-target rf reactive sputtering using metallic targets of zirconium and titanium. The compositional ratio of zirconium to titanium in the thin films was precisely controlled through rf power. Zirconium and titanium in the thin films were found to exist as mixtures of chemically bonded ZrO2 and TiO2 from XPS spectra. The zirconium-titanium-oxide thin films with compositional ratio x<0.42 were identified to have a tetragonal crystal structure, whereas those with x≥q 0.42 were identified to be in the amorphous state. The refractive index of the zirconium-titanium-oxide thin film at a wavelength of 550 nm changed from 2.25 to 2.55 according to compositional ratio x, and the dispersion of the refractive index was analyzed using the Lorentz oscillator model with four oscillators. It was clarified that the estimated oscillator energies E1 (10.5 eV) and E2 (6.5 eV) correspond to zirconium oxide, and that E3 (5.5 eV) and E4 (4.3 eV) correspond to titanium oxide from fundamental absorption spectra and photoconductivity.

  11. Electrosprayed metal oxide semiconductor films for sensitive and selective detection of hydrogen sulfide.

    PubMed

    Ghimbeu, Camelia Matei; Lumbreras, Martine; Schoonman, Joop; Siadat, Maryam

    2009-01-01

    Semiconductor metal oxide films of copper-doped tin oxide (Cu-SnO(2)), tungsten oxide (WO(3)) and indium oxide (In(2)O(3)) were deposited on a platinum coated alumina substrate employing the electrostatic spray deposition technique (ESD). The morphology studied with scanning electron microscopy (SEM) and atomic force microscopy (AFM) shows porous homogeneous films comprising uniformly distributed aggregates of nano particles. The X-ray diffraction technique (XRD) proves the formation of crystalline phases with no impurities. Besides, the Raman cartographies provided information about the structural homogeneity. Some of the films are highly sensitive to low concentrations of H(2)S (10 ppm) at low operating temperatures (100 and 200 °C) and the best response in terms of R(air)/R(gas) is given by Cu-SnO(2) films (2500) followed by WO(3) (1200) and In(2)O(3) (75). Moreover, all the films exhibit no cross-sensitivity to other reducing (SO(2)) or oxidizing (NO(2)) gases.

  12. Electrosprayed Metal Oxide Semiconductor Films for Sensitive and Selective Detection of Hydrogen Sulfide

    PubMed Central

    Ghimbeu, Camelia Matei; Lumbreras, Martine; Schoonman, Joop; Siadat, Maryam

    2009-01-01

    Semiconductor metal oxide films of copper-doped tin oxide (Cu-SnO2), tungsten oxide (WO3) and indium oxide (In2O3) were deposited on a platinum coated alumina substrate employing the electrostatic spray deposition technique (ESD). The morphology studied with scanning electron microscopy (SEM) and atomic force microscopy (AFM) shows porous homogeneous films comprising uniformly distributed aggregates of nano particles. The X-ray diffraction technique (XRD) proves the formation of crystalline phases with no impurities. Besides, the Raman cartographies provided information about the structural homogeneity. Some of the films are highly sensitive to low concentrations of H2S (10 ppm) at low operating temperatures (100 and 200 °C) and the best response in terms of Rair/Rgas is given by Cu-SnO2 films (2500) followed by WO3 (1200) and In2O3 (75). Moreover, all the films exhibit no cross-sensitivity to other reducing (SO2) or oxidizing (NO2) gases. PMID:22291557

  13. Oxidation kinetics of nanoscale copper films studied by terahertz transmission spectroscopy

    NASA Astrophysics Data System (ADS)

    Ramanandan, Gopika K. P.; Ramakrishnan, Gopakumar; Planken, Paul C. M.

    2012-06-01

    Terahertz (THz) transmission spectroscopy is used to measure the oxidation kinetics of copper thin films evaporated on silicon substrates. The transmission of broadband THz pulses from 1 to 7 THz through the copper film is measured while it gets oxidized at an elevated temperature in ambient air. The change in the transmitted THz electric field is correlated with the growth of the cuprous oxide layer and the decrease in thickness of the copper layer. Oxidation curves were obtained for heating temperatures of 120-150 °C and were found to follow a parabolic rate law. Using the Arrhenius equation, we calculate an activation energy for diffusion of 0.55 eV. By measuring the THz transmission through unoxidized copper layers of several thicknesses, we also measured the optical properties of thin copper films around the percolation threshold thickness of 7 nm. Around the percolation transition, the optical properties of freshly deposited copper thin films are very different from that of copper layers of the same thickness remaining after partial oxidation of thick copper films.

  14. Ion beam deposition and surface characterization of thin multi-component oxide films during growth.

    SciTech Connect

    Krauss, A.R.; Im, J.; Smentkowski, V.; Schultz, J.A.; Auciello, O.; Gruen, D.M.; Holocek, J.; Chang, R.P.H.

    1998-01-13

    Ion beam deposition of either elemental targets in a chemically active gas such as oxygen or nitrogen, or of the appropriate oxide or nitride target, usually with an additional amount of ambient oxygen or nitrogen present, is an effective means of depositing high quality oxide and nitride films. However, there are a number of phenomena which can occur, especially during the production of multicomponent films such as the ferroelectric perovskites or high temperature superconducting oxides, which make it desirable to monitor the composition and structure of the growing film in situ. These phenomena include thermodynamic (Gibbsian), and oxidation or nitridation-driven segregation, enhanced oxidation or nitridation through production of a highly reactive gas phase species such as atomic oxygen or ozone via interaction of the ion beam with the target, and changes in the film composition due to preferential sputtering of the substrate via primary ion backscattering and secondary sputtering of the film. Ion beam deposition provides a relatively low background pressure of the sputtering gas, but the ambient oxygen or nitrogen required to produce the desired phase, along with the gas burden produced by the ion source, result in a background pressure which is too high by several orders of magnitude to perform in situ surface analysis by conventional means. Similarly, diamond is normally grown in the presence of a hydrogen atmosphere to inhibit the formation of the graphitic phase.

  15. Electrical and optical properties of molybdenum doped zinc oxide films prepared by reactive RF magnetron sputtering

    SciTech Connect

    Reddy, R. Subba; Sreedhar, A.; Uthanna, S.

    2015-08-28

    Molybdenum doped zinc oxide (MZO) films were deposited on to glass substrates held at temperatures in the range from 303 to 673 K by reactive RF magnetron sputtering method. The chemical composition, crystallographic structure and surface morphology, electrical and optical properties of the films were determined. The films contained the molybdenum of 2.7 at. % in ZnO. The films deposited at 303 K were of X-ray amorphous. The films formed at 473 K were of nanocrystalline in nature with wurtzite structure. The crystallite size of the films was increased with the increase of substrate temperature. The optical transmittance of the films was in the visible range was 80–85%. The molybdenum (2.7 at %) doped zinc oxide films deposited at substrate temperature of 573 K were of nanocrystalline with electrical resistivity of 7.2×10{sup −3} Ωcm, optical transmittance of 85 %, optical band gap of 3.35 eV and figure of merit 30.6 Ω{sup −1}cm{sup −1}.

  16. Fabrication of (110)-one-axis-oriented perovskite-type oxide thin films and their application to buffer layer

    NASA Astrophysics Data System (ADS)

    Sato, Tomoya; Ichinose, Daichi; Kimura, Junichi; Inoue, Takaaki; Mimura, Takanori; Funakubo, Hiroshi; Uchiyama, Kiyoshi

    2016-10-01

    BaCe0.9Y0.1O3-δ (BCYO) and SrZr0.8Y0.2O3-δ (SZYO) thin films of perovskite-type oxides were deposited on (111)Pt/TiO x /SiO2/(100)Si substrates. X-ray diffraction patterns showed that the (110)-oriented BCYO and SZYO thin films were grown on (111)Pt/Si substrates directly without using any buffer layers. Thin films of SrRuO3 (SRO), a conductive perovskite-type oxide, were also deposited on those films and highly (110)-oriented SRO thin films were obtained. We believe that this (110)-oriented SRO works as a buffer layer to deposit (110)-oriented perovskite-type ferroelectric oxide thin films as well as a bottom electrode and can modify the ferroelectric properties of the oxide thin films by controlling their crystallographic orientations.

  17. Influence of controlled surface oxidation on the magnetic anisotropy of Co ultrathin films

    SciTech Connect

    Di, N.; Maroun, F. Allongue, P.; Kubal, J.; Zeng, Z.; Greeley, J.

    2015-03-23

    We studied the influence of controlled surface-limited oxidation of electrodeposited epitaxial Co(0001)/Au(111) films on their magnetic anisotropy energy using real time in situ magneto optical Kerr effect and density functional theory (DFT) calculations. We investigated the Co first electrochemical oxidation step which we demonstrate to be completely reversible and determined the structure of this oxide layer. We show that the interface magnetic anisotropy of the Co film increases by 0.36 erg/cm{sup 2} upon Co surface oxidation. We performed DFT calculations to determine the different surface structures in a wide potential range as well as the charge transfer at the Co surface. Our results suggest that the magnetic anisotropy change is correlated with a positive charge increase of 0.54 e{sup −} for the Co surface atom upon oxidation.

  18. Influence of neodymium concentration on excitation and emission properties of Nd doped gallium oxide nanocrystalline films

    NASA Astrophysics Data System (ADS)

    Podhorodecki, A.; Banski, M.; Misiewicz, J.; Lecerf, C.; Marie, P.; Cardin, J.; Portier, X.

    2010-09-01

    Gallium oxide and more particularly β-Ga2O3 matrix is an excellent material for new generation of devices electrically or optically driven as it is known as the widest band gap transparent conductive oxide. In this paper, the optical properties of neodymium doped gallium oxide films grown by magnetron sputtering have been analyzed. The influence of the Nd ions concentration on the excitation/emission mechanisms of Nd ions and the role of gallium oxide matrix have been investigated. The grain size reduction into gallium oxide films have been observed when concentration of Nd increases. It has been found for all samples that the charge transfer is the main excitation mechanism for Nd ions where defect states play an important role as intermediate states. As a consequence Nd emission efficiency increases with temperature giving rise to most intensive emission at 1087 nm at room temperature.

  19. Influence of neodymium concentration on excitation and emission properties of Nd doped gallium oxide nanocrystalline films

    SciTech Connect

    Podhorodecki, A.; Banski, M.; Misiewicz, J.; Lecerf, C.; Marie, P.; Cardin, J.; Portier, X.

    2010-09-15

    Gallium oxide and more particularly {beta}-Ga{sub 2}O{sub 3} matrix is an excellent material for new generation of devices electrically or optically driven as it is known as the widest band gap transparent conductive oxide. In this paper, the optical properties of neodymium doped gallium oxide films grown by magnetron sputtering have been analyzed. The influence of the Nd ions concentration on the excitation/emission mechanisms of Nd ions and the role of gallium oxide matrix have been investigated. The grain size reduction into gallium oxide films have been observed when concentration of Nd increases. It has been found for all samples that the charge transfer is the main excitation mechanism for Nd ions where defect states play an important role as intermediate states. As a consequence Nd emission efficiency increases with temperature giving rise to most intensive emission at 1087 nm at room temperature.

  20. Conduction and Reactivity in Heterogeneous-Molecular Catalysis: New Insights in Water Oxidation Catalysis by Phosphate Cobalt Oxide Films.

    PubMed

    Costentin, Cyrille; Porter, Thomas R; Savéant, Jean-Michel

    2016-05-04

    Cyclic voltammetry of phosphate cobalt oxide (CoPi) films catalyzing O2-evolution from water oxidation as a function of scan rate, phosphate concentration and film thickness allowed for new insights into the coupling between charge transport and catalysis. At pH = 7 and low buffer concentrations, the film is insulating below 0.8 (V vs SHE) but becomes conductive above 0.9 (V vs SHE). Between 1.0 to 1.3 (V vs SHE), the mesoporous structure of the film gives rise to a large thickness-dependent capacitance. At higher buffer concentrations, two reversible proton-coupled redox couples appear over the capacitive response with 0.94 and 1.19 (V vs SHE) pH = 7 standard potentials. The latter is, at most, very weakly catalytic and not responsible for the large catalytic current observed at higher potentials. CV-response analysis showed that the amount of redox-active cobalt-species in the film is small, less than 10% of total. The catalytic process involves a further proton-coupled-electron-transfer and is so fast that it is controlled by diffusion of phosphate, the catalyst cofactor. CV-analysis with newly derived relationships led to a combination of the catalyst standard potential with the catalytic rate constant and a lower-limit estimation of these parameters. The large currents resulting from the fast catalytic reaction result in significant potential losses related to charge transport through the film. CoPi films appear to combine molecular catalysis with semiconductor-type charge transport. This mode of heterogeneous molecular catalysis is likely to occur in many other catalytic films.

  1. Novel Low Temperature Processing for Enhanced Properties of Ion Implanted Thin Films and Amorphous Mixed Oxide Thin Film Transistors

    NASA Astrophysics Data System (ADS)

    Vemuri, Rajitha

    This research emphasizes the use of low energy and low temperature post processing to improve the performance and lifetime of thin films and thin film transistors, by applying the fundamentals of interaction of materials with conductive heating and electromagnetic radiation. Single frequency microwave anneal is used to rapidly recrystallize the damage induced during ion implantation in Si substrates. Volumetric heating of the sample in the presence of the microwave field facilitates quick absorption of radiation to promote recrystallization at the amorphous-crystalline interface, apart from electrical activation of the dopants due to relocation to the substitutional sites. Structural and electrical characterization confirm recrystallization of heavily implanted Si within 40 seconds anneal time with minimum dopant diffusion compared to rapid thermal annealed samples. The use of microwave anneal to improve performance of multilayer thin film devices, e.g. thin film transistors (TFTs) requires extensive study of interaction of individual layers with electromagnetic radiation. This issue has been addressed by developing detail understanding of thin films and interfaces in TFTs by studying reliability and failure mechanisms upon extensive stress test. Electrical and ambient stresses such as illumination, thermal, and mechanical stresses are inflicted on the mixed oxide based thin film transistors, which are explored due to high mobilities of the mixed oxide (indium zinc oxide, indium gallium zinc oxide) channel layer material. Semiconductor parameter analyzer is employed to extract transfer characteristics, useful to derive mobility, subthreshold, and threshold voltage parameters of the transistors. Low temperature post processing anneals compatible with polymer substrates are performed in several ambients (oxygen, forming gas and vacuum) at 150 °C as a preliminary step. The analysis of the results pre and post low temperature anneals using device physics fundamentals

  2. Film growth and structure design in the barium oxide-strontium oxide-titanium dioxide system

    NASA Astrophysics Data System (ADS)

    Fisher, Patrick J.

    This thesis describes the growth and characterization of thin films in the SrO-BaO-TiO2 system. The films are grown by molecular beam cpitaxy (MBE) and pulsed laser deposition (PLD) on ceramic substrates, and characterized using X-ray diffraction (XRD), atomic force microscopy (AFM), reflection-high energy electron diffraction (RHEED), and transmission electron microscopy (TEM). Films are grown with varied global and initial local stoichiometries, with the goal of determining the stability of specific cation organizations. Simple oxides, TiO2 (anatase) and SrO (rock salt) were grown on oxide substrates using MBE. Growth conditions, including substrate material, substrate temperature, O3 flux, and metal flux, are varied in each case. It is observed that the growth morphology of anatase is highly dependent on the ozone flux, with fluxes of 1.00 sccm and greater resulting in flat anatase surfaces. Increased roughness at higher substrate was determined to be a result of rutile inclusions. Growth oscillations are observed in the RHEED intensity for both TiO2 and SrO in overlapping regions of growth space, indicating 2D growth modes. Varied shuttering sequences were used during MBE growth of perovskites: globally non-stoichiometric films, as well as locally non-stoichiometric but globally stoichiometric perovskite. Films were grown within a (SrO) m(TiO2)n framework, where growth cycles involved m monolayers of SrO followed by n monolayers of TiO2. XRD results indicate that Ruddlesden-Popper defects, that is, rock salt double layers, enable incorporation of all levels of Sr excess, whereas excess Ti is observed to incorporate into the perovskite structure only at extreme excesses. A series of films with m equal to n were grown; that is, multiple monolayers of SrO deposited followed by multiple monolayers of TiO2. These initially locally non-stoichiometric arrangements interreact to form highly crystalline perovskite, even with layer thicknesses of up to 33 monolayers. The

  3. Ionization potentials of transparent conductive indium tin oxide films covered with a single layer of fluorine-doped tin oxide nanoparticles grown by spray pyrolysis deposition

    SciTech Connect

    Fukano, Tatsuo; Motohiro, Tomoyoshi; Ida, Takashi; Hashizume, Hiroo

    2005-04-15

    Indium tin oxide (ITO) films deposited with single layers of monodispersive fluorine-doped tin oxide (FTO) nanoparticles of several nanometers in size were grown on glass substrates by intermittent spray pyrolysis deposition using conventional atomizers. These films have significantly higher ionization potentials than the bare ITO and FTO films grown using the same technique. The ITO films covered with FTO particles of 7 nm in average size show an ionization potential of 5.01 eV, as compared with {approx}4.76 and {approx}4.64 eV in ITO and FTO films, respectively, which decreases as the FTO particle size increases. The ionization potentials are practically invariant against oxidation and reduction treatments, promising a wide application of the films to transparent conducting oxide electrodes in organic electroluminescent devices and light-emitting devices of high efficiencies.

  4. Nanoscale characterization of oxidized ultrathin Co-films by ballistic electron emission microscopy

    NASA Astrophysics Data System (ADS)

    Eng Johnson Goh, Kuan; Wang, Simin; Tan, Siew Ting Melissa; Zhang, Zheng; Kawai, Hiroyo; Troadec, Cedric; Ng, Vivian

    2016-01-01

    In anticipation of devices scaling down further to the few nanometer regime, the ability to characterize material localized within the few nm of a critical device region poses a current challenge, particularly when the material is already buried under other material layers such as under a metal contact. Conventional techniques typically provide indirect information of the nanoscale material quality through a surface or volume averaging perspective. Here we present a study of local (nm range) oxidation in few nanometer thick Co-films using Ballistic Electron Emission Microscopy/Spectroscopy (BEEM/BEES). Co films were grown on n-Si(111) substrates, oxidized in ambient atmosphere before capping with a thin Au film to prevent further oxidation and enable BEEM measurements. In addition to BEES, the temporal progression of Co oxidation was also tracked by X-ray Photoelectron Spectroscopy. At room temperature, we report that the electron injection thresholds are sufficiently different for local regions with Co and oxidized-Co enabling their distinction in BEEM measurements. Our results demonstrate the possibility of using BEEM for nanoscale spatial mapping of the oxidized regions in Co-films, and this can provide critical information toward the successful fabrication of next generation Co-based nano-devices.

  5. Reduction of a thin chromium oxide film on Inconel surface upon treatment with hydrogen plasma

    NASA Astrophysics Data System (ADS)

    Vesel, Alenka; Mozetic, Miran; Balat-Pichelin, Marianne

    2016-11-01

    Inconel samples with a surface oxide film composed of solely chromium oxide with a thickness of approximately 700 nm were exposed to low-pressure hydrogen plasma at elevated temperatures to determine the suitable parameters for reduction of the oxide film. The hydrogen pressure during treatment was set to 60 Pa. Plasma was created by a surfaguide microwave discharge in a quartz glass tube to allow for a high dissociation fraction of hydrogen molecules. Auger electron depth profiling (AES) was used to determine the decay of the oxygen in the surface film and X-ray diffraction (XRD) to measure structural modifications. During hydrogen plasma treatment, the oxidized Inconel samples were heated to elevated temperatures. The reduction of the oxide film started at temperatures of approximately 1300 K (considering the emissivity of 0.85) and the oxide was reduced in about 10 s of treatment as revealed by AES. The XRD showed sharper substrate peaks after the reduction. Samples treated in hydrogen atmosphere under the same conditions have not been reduced up to approximately 1500 K indicating usefulness of plasma treatment.

  6. Low-temperature atomic layer deposition of copper(II) oxide thin films

    SciTech Connect

    Iivonen, Tomi Hämäläinen, Jani; Mattinen, Miika; Popov, Georgi; Leskelä, Markku; Marchand, Benoît; Mizohata, Kenichiro; Kim, Jiyeon; Fischer, Roland A.

    2016-01-15

    Copper(II) oxide thin films were grown by atomic layer deposition (ALD) using bis-(dimethylamino-2-propoxide)copper [Cu(dmap){sub 2}] and ozone in a temperature window of 80–140 °C. A thorough characterization of the films was performed using x-ray diffraction, x-ray reflectivity, UV‐Vis spectrophotometry, atomic force microscopy, field emission scanning electron microscopy, x-ray photoelectron spectroscopy, and time-of-flight elastic recoil detection analysis techniques. The process was found to produce polycrystalline copper(II) oxide films with a growth rate of 0.2–0.3 Å per cycle. Impurity content in the films was relatively small for a low temperature ALD process.

  7. Interfacial control of oxygen vacancy doping and electrical conduction in thin film oxide heterostructures.

    SciTech Connect

    Veal, Boyd W.; Kim, Seong Keun; Zapol, Peter; Iddir, Hakim; Baldo, Peter M.; Eastman, Jeffrey A.

    2016-06-01

    Oxygen vacancies in proximity to surfaces and heterointerfaces in oxide thin film heterostructures have major effects on properties, resulting, for example, in emergent conduction behaviour, large changes in metal-insulator transition temperatures or enhanced catalytic activity. Here we report the discovery of a means of reversibly controlling the oxygen vacancy concentration and distribution in oxide heterostructures consisting of electronically conducting In2O3 films grown on ionically conducting Y2O3-stabilized ZrO2 substrates. Oxygen ion redistribution across the heterointerface is induced using an applied electric field oriented in the plane of the interface, resulting in controlled oxygen vacancy (and hence electron) doping of the film and possible orders-of-magnitude enhancement of the film's electrical conduction. The reversible modified behaviour is dependent on interface properties and is attained without cation doping or changes in the gas environment.

  8. Interfacial control of oxygen vacancy doping and electrical conduction in thin film oxide heterostructures

    SciTech Connect

    Veal, Boyd W.; Kim, Seong Keun; Zapol, Peter; Iddir, Hakim; Baldo, Peter M.; Eastman, Jeffrey A.

    2016-06-10

    Oxygen vacancies in proximity to surfaces and heterointerfaces in oxide thin film heterostructures have major effects on properties, resulting, for example, in emergent conduction behavior, large changes in metal-insulator transition temperatures, or enhanced catalytic activity. Here in this paper, we report the discovery of a means of reversibly controlling the oxygen vacancy concentration and distribution in oxide heterostructures consisting of electronically conducting In2O3 films grown on ionically conducting Y2O3-stabilized ZrO2 substrates. Oxygen ion redistribution across the heterointerface is induced using an applied electric field oriented in the plane of the interface, resulting in controlled oxygen vacancy (and hence electron) doping of the film and possible orders-of-magnitude enhancement of the film's electrical conduction. The reversible modified behavior is dependent on interface properties and is attained without cation doping or changes in the gas environment.

  9. Characteristics of Thermally Reduced Graphene Oxide Thin Film as DSSC Counter Electrode

    NASA Astrophysics Data System (ADS)

    Yuliasari, F.; Aprilia, A.; Syakir, N.; Safriani, L.; Saragi, T.; Risdiana; Hidayat, S.; Bahtiar, A.; Siregar, R.; Fitrilawati

    2017-05-01

    We report characteristics of reduced graphene oxide (RGO) as a counter electrode for dye-sensitized solar cell (DSSC). The RGO thin films were prepared on FTO (Fluorine-doped Tin Oxide) substrates and followed by a reduction process. The RGO film was used as a counter electrode in a DSSC device, with a structure of FTO/TiO2/ruthenium dye/mosalyte/RGO/FTO. UV-Vis measurements show an increasing absorption spectrum of RGO film after thermal reduction process and the FT-IR spectrum confirms a removal of the oxygen containing groups after thermal reduction process. The efficiency (η) of the DSSC that applied RGO film as a counter electrode is 0.96%.

  10. Fabrication of transparent cellulose acetate/graphene oxide nanocomposite film for UV shielding

    SciTech Connect

    Jahan, Nusrat; Khan, Wasi Azam, Ameer; Naqvi, A. H.

    2016-05-23

    In this work, we have fabricated transparent cellulose acetate/graphene oxide nanocomposite (CAGONC) films for ultraviolet radiations (UVR) shielding. Graphene oxide (GO) was synthesized by modified Hummer’s method and CAGONC films were fabricated by solvent casting method. The films were analyzed using characterization techniques like x-ray diffraction (XRD), energy dispersive x-ray (EDX) equipped scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and ultra-violet visible (UV-VIS) spectroscopy. Four films were prepared by varying the wt% of GO (0.1wt%, 0.2wt% and 0.3wt%) with respect to cellulose acetate (CA). UV-vis measurements exhibit optical transparency in the range of 76-99% for visible light while ultra-violet radiation was substantially shielded.

  11. Interfacial control of oxygen vacancy doping and electrical conduction in thin film oxide heterostructures

    DOE PAGES

    Veal, Boyd W.; Kim, Seong Keun; Zapol, Peter; ...

    2016-06-10

    Oxygen vacancies in proximity to surfaces and heterointerfaces in oxide thin film heterostructures have major effects on properties, resulting, for example, in emergent conduction behavior, large changes in metal-insulator transition temperatures, or enhanced catalytic activity. Here in this paper, we report the discovery of a means of reversibly controlling the oxygen vacancy concentration and distribution in oxide heterostructures consisting of electronically conducting In2O3 films grown on ionically conducting Y2O3-stabilized ZrO2 substrates. Oxygen ion redistribution across the heterointerface is induced using an applied electric field oriented in the plane of the interface, resulting in controlled oxygen vacancy (and hence electron) dopingmore » of the film and possible orders-of-magnitude enhancement of the film's electrical conduction. The reversible modified behavior is dependent on interface properties and is attained without cation doping or changes in the gas environment.« less

  12. Production of amorphous tin oxide thin films and microstructural transformation induced by heat treatment

    NASA Astrophysics Data System (ADS)

    Chen, Z. W.; Lai, J. K. L.; Shek, C. H.; Chen, H. D.

    2005-10-01

    X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and high resolution transmission electron microscopy were used to study tin oxide thin films deposited on Si(100) substrates at room temperature using pulsed laser deposition techniques with a sintered cassiterite SnO2 target and subsequently heat-treated. X-ray diffraction and scanning electron microscopy results demonstrated that the as-prepared thin films consisted of an amorphous matrix as well as plume-like features, which are shown many micropores. The thin films that were heat treated for 2 h at 150 °C had tetragonal rutile nanocrystalline SnO2 structures. The microstructural evolution of the tin oxide thin films during the heat treatment is discussed in the paper.

  13. Interfacial control of oxygen vacancy doping and electrical conduction in thin film oxide heterostructures.

    PubMed

    Veal, Boyd W; Kim, Seong Keun; Zapol, Peter; Iddir, Hakim; Baldo, Peter M; Eastman, Jeffrey A

    2016-06-10

    Oxygen vacancies in proximity to surfaces and heterointerfaces in oxide thin film heterostructures have major effects on properties, resulting, for example, in emergent conduction behaviour, large changes in metal-insulator transition temperatures or enhanced catalytic activity. Here we report the discovery of a means of reversibly controlling the oxygen vacancy concentration and distribution in oxide heterostructures consisting of electronically conducting In2O3 films grown on ionically conducting Y2O3-stabilized ZrO2 substrates. Oxygen ion redistribution across the heterointerface is induced using an applied electric field oriented in the plane of the interface, resulting in controlled oxygen vacancy (and hence electron) doping of the film and possible orders-of-magnitude enhancement of the film's electrical conduction. The reversible modified behaviour is dependent on interface properties and is attained without cation doping or changes in the gas environment.

  14. Fabrication of transparent cellulose acetate/graphene oxide nanocomposite film for UV shielding

    NASA Astrophysics Data System (ADS)

    Jahan, Nusrat; Khan, Wasi; Azam, Ameer; Naqvi, A. H.

    2016-05-01

    In this work, we have fabricated transparent cellulose acetate/graphene oxide nanocomposite (CAGONC) films for ultraviolet radiations (UVR) shielding. Graphene oxide (GO) was synthesized by modified Hummer's method and CAGONC films were fabricated by solvent casting method. The films were analyzed using characterization techniques like x-ray diffraction (XRD), energy dispersive x-ray (EDX) equipped scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and ultra-violet visible (UV-VIS) spectroscopy. Four films were prepared by varying the wt% of GO (0.1wt%, 0.2wt% and 0.3wt%) with respect to cellulose acetate (CA). UV-vis measurements exhibit optical transparency in the range of 76-99% for visible light while ultra-violet radiation was substantially shielded.

  15. Interfacial control of oxygen vacancy doping and electrical conduction in thin film oxide heterostructures

    PubMed Central

    Veal, Boyd W.; Kim, Seong Keun; Zapol, Peter; Iddir, Hakim; Baldo, Peter M.; Eastman, Jeffrey A.

    2016-01-01

    Oxygen vacancies in proximity to surfaces and heterointerfaces in oxide thin film heterostructures have major effects on properties, resulting, for example, in emergent conduction behaviour, large changes in metal-insulator transition temperatures or enhanced catalytic activity. Here we report the discovery of a means of reversibly controlling the oxygen vacancy concentration and distribution in oxide heterostructures consisting of electronically conducting In2O3 films grown on ionically conducting Y2O3-stabilized ZrO2 substrates. Oxygen ion redistribution across the heterointerface is induced using an applied electric field oriented in the plane of the interface, resulting in controlled oxygen vacancy (and hence electron) doping of the film and possible orders-of-magnitude enhancement of the film's electrical conduction. The reversible modified behaviour is dependent on interface properties and is attained without cation doping or changes in the gas environment. PMID:27283250

  16. Bismuth Oxide Thin Films Deposited on Silicon Through Pulsed Laser Ablation, for Infrared Detectors

    NASA Astrophysics Data System (ADS)

    Condurache-Bota, Simona; Constantinescu, Catalin; Tigau, Nicolae; Praisler, Mirela

    2016-12-01

    Infrared detectors are used in many human activities, from industry to military, telecommunications, environmental studies and even medicine. Bismuth oxide thin films have proved their potential for optoelectronic applications, but their uses as infrared sensors have not been thoroughly studied so far. In this paper, pulsed laser ablation of pure bismuth targets within a controlled oxygen atmosphere is proposed for the deposition of bismuth oxide films on Si (100) substrates. Crystalline films were obtained, whose uniformity depends on the deposition conditions (number of laser pulses and the use of a radio-frequency (RF) discharge of the oxygen inside the deposition chamber). The optical analysis proved that the refractive index of the films is higher than 3 and that their optical bandgap is around 1eV, recommending them for infrared applications.

  17. Electrochromic properties of tungsten-titanium oxide films.

    PubMed

    Chen, Ya-Chi; Lin, Tai-Nan; Chen, Tien-Lai; Li, Yun-Da; Weng, Ko-Wei

    2012-02-01

    The last decade has seen great in electrochromic (EC) technology for smart windows and displays. In this study, WTiOx films formed from TiO2 and WO3 were deposited onto ITO glass with a sheet resistance of 10 Omega cm and on silicon substrates, by pulsed magnetron sputtering using a W and Ti alloy target. The films were deposited at plasma powers 100, 200, 300, 400 and 500 W using a gaseous Ar (150 sccm)/O2 (50 sccm) mixture; the working pressure was fixed at 5E-2 torr. The film thickness increased with the plasma power. However, increasing the plasma power yielded a more crystalline structure with poorer electrochromic properties. The influence of Ti doping and plasma power on the structural, optical and electrochromic properties of the WTiOx thin films was studied. WTiOx films grown at various plasma powers of under 400 W were amorphous. Deposition of films at 400 W yielded the optimal electrochromic properties, with high optical modulation, high coloration efficiency and the lowest color memory effect at wavelengths 400, 550 and 800 nm. An XPS study indicated that Ti can stabilize the valence state of W6+. The improvements caused by the doping with Ti were tested: an optical density (OD) of close to 0.85 and a maximum delta T (%) at 400 nm of 25.8%, at 550 nm of 52.5% and at 800 nm (in the near-IR region) of 62.4%.

  18. Stable solar-driven oxidation of water by semiconducting photoanodes protected by transparent catalytic nickel oxide films.

    PubMed

    Sun, Ke; Saadi, Fadl H; Lichterman, Michael F; Hale, William G; Wang, Hsin-Ping; Zhou, Xinghao; Plymale, Noah T; Omelchenko, Stefan T; He, Jr-Hau; Papadantonakis, Kimberly M; Brunschwig, Bruce S; Lewis, Nathan S

    2015-03-24

    Reactively sputtered nickel oxide (NiOx) films provide transparent, antireflective, electrically conductive, chemically stable coatings that also are highly active electrocatalysts for the oxidation of water to O2(g). These NiOx coatings provide protective layers on a variety of technologically important semiconducting photoanodes, including textured crystalline Si passivated by amorphous silicon, crystalline n-type cadmium telluride, and hydrogenated amorphous silicon. Under anodic operation in 1.0 M aqueous potassium hydroxide (pH 14) in the presence of simulated sunlight, the NiOx films stabilized all of these self-passivating, high-efficiency semiconducting photoelectrodes for >100 h of sustained, quantitative solar-driven oxidation of water to O2(g).

  19. Stable solar-driven oxidation of water by semiconducting photoanodes protected by transparent catalytic nickel oxide films

    DOE PAGES

    Sun, Ke; Saadi, Fadl H.; Lichterman, Michael F.; ...

    2015-03-11

    Reactively sputtered nickel oxide (NiOx) films provide transparent, antireflective, electrically conductive, chemically stable coatings that also are highly active electrocatalysts for the oxidation of water to O2(g). These NiOx coatings provide protective layers on a variety of technologically important semiconducting photoanodes, including textured crystalline Si passivated by amorphous silicon, crystalline n-type cadmium telluride, and hydrogenated amorphous silicon. Finally, under anodic operation in 1.0 M aqueous potassium hydroxide (pH 14) in the presence of simulated sunlight, the NiOx films stabilized all of these self-passivating, high-efficiency semiconducting photoelectrodes for >100 h of sustained, quantitative solar-driven oxidation of water to O2(g).

  20. Stable solar-driven oxidation of water by semiconducting photoanodes protected by transparent catalytic nickel oxide films

    PubMed Central

    Sun, Ke; Saadi, Fadl H.; Lichterman, Michael F.; Hale, William G.; Wang, Hsin-Ping; Zhou, Xinghao; Plymale, Noah T.; Omelchenko, Stefan T.; He, Jr-Hau; Papadantonakis, Kimberly M.; Brunschwig, Bruce S.; Lewis, Nathan S.

    2015-01-01

    Reactively sputtered nickel oxide (NiOx) films provide transparent, antireflective, electrically conductive, chemically stable coatings that also are highly active electrocatalysts for the oxidation of water to O2(g). These NiOx coatings provide protective layers on a variety of technologically important semiconducting photoanodes, including textured crystalline Si passivated by amorphous silicon, crystalline n-type cadmium telluride, and hydrogenated amorphous silicon. Under anodic operation in 1.0 M aqueous potassium hydroxide (pH 14) in the presence of simulated sunlight, the NiOx films stabilized all of these self-passivating, high-efficiency semiconducting photoelectrodes for >100 h of sustained, quantitative solar-driven oxidation of water to O2(g). PMID:25762067

  1. Tin etching from metallic and oxidized scandium thin films

    NASA Astrophysics Data System (ADS)

    Pachecka, M.; Lee, C. J.; Sturm, J. M.; Bijkerk, F.

    2017-08-01

    The role of oxide on Sn adhesion to Sc surfaces was studied with in-situ ellipsometry, X-ray photoelectron spectroscopy and secondary electron microscopy. Sn etching with hydrogen radicals was performed on metallic Sc, metallic Sc with a native oxide, and a fully oxidized Sc layer. The results show that Sn adsorbs rather weakly to a non-oxidized Sc surface, and is etched relatively easily by atomic hydrogen. In contrast, the presence of native oxide on Sc allows Sn to adsorb more strongly to the surface, slowing the etching. Furthermore, thinner layers of scandium oxide result in weaker Sn adsorption, indicating that the layer beneath the oxide plays a significant role in determining the adsorption strength. Unexpectedly, for Sn on Sc2O3, and, to a lesser extent, for Sn on Sc, the etch rate shows a variation over time, which is explained by surface restructuring, temperature change, and hydrogen adsorption saturation.

  2. Performance and Stress Analysis of Metal Oxide Films for CMOS-Integrated Gas Sensors

    PubMed Central

    Filipovic, Lado; Selberherr, Siegfried

    2015-01-01

    The integration of gas sensor components into smart phones, tablets and wrist watches will revolutionize the environmental health and safety industry by providing individuals the ability to detect harmful chemicals and pollutants in the environment using always-on hand-held or wearable devices. Metal oxide gas sensors rely on changes in their electrical conductance due to the interaction of the oxide with a surrounding gas. These sensors have been extensively studied in the hopes that they will provide full gas sensing functionality with CMOS integrability. The performance of several metal oxide materials, such as tin oxide (SnO2), zinc oxide (ZnO), indium oxide (In2O3) and indium-tin-oxide (ITO), are studied for the detection of various harmful or toxic cases. Due to the need for these films to be heated to temperatures between 250 °C and 550 °C during operation in order to increase their sensing functionality, a considerable degradation of the film can result. The stress generation during thin film deposition and the thermo-mechanical stress that arises during post-deposition cooling is analyzed through simulations. A tin oxide thin film is deposited using the efficient and economical spray pyrolysis technique, which involves three steps: the atomization of the precursor solution, the transport of the aerosol droplets towards the wafer and the decomposition of the precursor at or near the substrate resulting in film growth. The details of this technique and a simulation methodology are presented. The dependence of the deposition technique on the sensor performance is also discussed. PMID:25815445

  3. Performance and stress analysis of metal oxide films for CMOS-integrated gas sensors.

    PubMed

    Filipovic, Lado; Selberherr, Siegfried

    2015-03-25

    The integration of gas sensor components into smart phones, tablets and wrist watches will revolutionize the environmental health and safety industry by providing individuals the ability to detect harmful chemicals and pollutants in the environment using always-on hand-held or wearable devices. Metal oxide gas sensors rely on changes in their electrical conductance due to the interaction of the oxide with a surrounding gas. These sensors have been extensively studied in the hopes that they will provide full gas sensing functionality with CMOS integrability. The performance of several metal oxide materials, such as tin oxide (SnO2), zinc oxide (ZnO), indium oxide (In2O3) and indium-tin-oxide (ITO), are studied for the detection of various harmful or toxic cases. Due to the need for these films to be heated to temperatures between 250°C and 550°C during operation in order to increase their sensing functionality, a considerable degradation of the film can result. The stress generation during thin film deposition and the thermo-mechanical stress that arises during post-deposition cooling is analyzed through simulations. A tin oxide thin film is deposited using the efficient and economical spray pyrolysis technique, which involves three steps: the atomization of the precursor solution, the transport of the aerosol droplets towards the wafer and the decomposition of the precursor at or near the substrate resulting in film growth. The details of this technique and a simulation methodology are presented. The dependence of the deposition technique on the sensor performance is also discussed.

  4. Preparation and activation of micro-arc oxidation films on a TLM titanium alloy.

    PubMed

    Yu, S; Yu, Z T

    2008-12-01

    In order to improve the biocompatibility and surface activity of a TLM alloy, a layer of a porous TiO(2) film was prepared by the micro-arc oxidation method on the surface, and then the NH(-)(2) active group was introduced on the film by an activation treatment in an aminated solution. The phase identification and surface characteristics of the micro-arc oxidation films were characterized by XRD, XPS, SEM and EDS. The in vitro blood compatibility of the TLM alloy samples with and without surface modification was evaluated by contact angle tests, hemolysis tests and electrochemical tests. The results indicate that the biocompatibility and surface activity of the TLM alloy could be remarkably improved by surface modification of micro-arc oxidation and activation treatment.

  5. Thermal stability of an ultrathin hafnium oxide film on plasma nitrided Si(100)

    NASA Astrophysics Data System (ADS)

    Skaja, K.; Schönbohm, F.; Weier, D.; Lühr, T.; Keutner, C.; Berges, U.; Westphal, C.

    2013-10-01

    We report on the thermal stability of an ultrathin hafnium oxide film on a plasma nitrided Si(100) surface. The ultrathin silicon nitride buffer layer was produced by an ECR-plasma ion source. Onto this buffer layer a thin hafnium oxide film was prepared by electron beam evaporation. The thermal stability of the layer stack was checked by systematic annealing steps. A detailed angle resolved X-ray photoelectron spectroscopy study of the interfaces is presented. For chemical surface studies high-resolution spectra of the Si 2p and Hf 4f signals were taken. It is demonstrated that the thermal stability of hafnium oxide thin films can be increased by a smooth and homogenous buffer layer of silicon nitride.

  6. Effect of Oxidation on Localized Heat Generation and Dielectric Breakdown of Low-Density Polyethylene Film

    NASA Astrophysics Data System (ADS)

    Tsurimoto, Takao; Nagao, Masayuki; Kosaki, Masamitsu

    1995-12-01

    The effect of oxidation on localized heat generation and dielectric breakdown in low-density polyethylene (LDPE) film was studied by thermography. In the non-McKeown-type epoxy-free electrode system, localized heat generation of LDPE film leading to dielectric breakdown increased and breakdown strength decreased upon oxidation. In the McKeown-type specimen, however, the breakdown strength of oxidized LDPE film is higher than that of an unoxidized one. It is considered that enhancement of the thermal process is a major factor of breakdown in the epoxy-free electrode system and that homo-space charge and/or electron scattering effect is dominant in the McKeown type specimen.

  7. Environment-dependent photochromism of silver nanoparticles interfaced with metal-oxide films

    NASA Astrophysics Data System (ADS)

    Fu, Shencheng; Sun, Shiyu; Zhang, Xintong; Zhang, Cen; Zhao, Xiaoning; Liu, Yichun

    2015-12-01

    Different metal-oxide films were fabricated by radio frequency magnetron sputtering. Further, a layer of silver nanoparticles (NPs) was deposited on the surface of the substrate by physical sputtering. Photochromism of the silver/metal-oxide nanocomposite films were investigated in situ under the irradiation of a linearly-polarized green laser beam (532 nm). Silver NPs were found to be easily photo-dissolved on the n-type metal-oxide films. By changing experimental conditions, it was also verified that both oxygen and humidity accelerate the photochromism of silver NPs. The corresponding micro-mechanism on charge separation and Ag+-ions mobility was also discussed. These results provided theoretical basis for the application of silver NPs in biological, chemical and medical areas.

  8. Nickel vacancy behavior in the electrical conductance of nonstoichiometric nickel oxide film

    SciTech Connect

    Kim, Dong Soo; Lee, Hee Chul

    2012-08-01

    Nickel vacancy behavior in electrical conductance is systematically investigated using various analysis methods on nickel oxide films deposited at different oxygen partial pressures. The results of Rutherford backscattering, x-ray diffraction, and Auger electron spectroscopy analyses demonstrate that the sputtered nickel oxide films are nickel-deficient. Through the deconvolution of Ni2p and O1s spectra in the x-ray photoelectron spectroscopy data, the number of Ni{sup 3+} ions is found to increase with the O{sub 2} ratio during the deposition. According to the vacancy model, nickel vacancies created from the non-stoichiometry are concluded to produce Ni{sup 3+} ions which lead to an increment of the conductivity of the nickel oxide films due to the increase of the hole concentration.

  9. Fabrication of ion conductive tin oxide-phosphate amorphous thin films by atomic layer deposition

    SciTech Connect

    Park, Suk Won; Jang, Dong Young; Kim, Jun Woo; Shim, Joon Hyung

    2015-07-15

    This work reports the atomic layer deposition (ALD) of tin oxide-phosphate films using tetrakis(dimethylamino)tin and trimethyl phosphate as precursors. The growth rates were 1.23–1.84 Å/cycle depending upon the deposition temperature and precursor combination. The ionic conductivity of the ALD tin oxide-phosphate films was evaluated by cross-plane impedance measurements in the temperature range of 50–300 °C under atmospheric air, with the highest conductivity measured as 1.92 × 10{sup −5} S cm{sup −1} at 300 °C. Furthermore, high-resolution x-ray photoelectron spectroscopy exhibited two O1s peaks that were classified as two subpeaks of hydroxyl ions and oxygen ions, revealing that the quantity of hydroxyl ions in the ALD tin oxide-phosphate films influences their ionic conductivity.

  10. Molybdenum as a contact material in zinc tin oxide thin film transistors

    SciTech Connect

    Hu, W.; Peterson, R. L.

    2014-05-12

    Amorphous oxide semiconductors are of increasing interest for a variety of thin film electronics applications. Here, the contact properties of different source/drain electrode materials to solution-processed amorphous zinc tin oxide (ZTO) thin-film transistors are studied using the transmission line method. The width-normalized contact resistance between ZTO and sputtered molybdenum is measured to be 8.7 Ω-cm, which is 10, 20, and 600 times smaller than that of gold/titanium, indium tin oxide, and evaporated molybdenum electrodes, respectively. The superior contact formed using sputtered molybdenum is due to a favorable work function lineup, an insulator-free interface, bombardment of ZTO during molybdenum sputtering, and trap-assisted tunneling. The transfer length of the sputtered molybdenum/ZTO contact is 0.34 μm, opening the door to future radio-frequency sub-micron molybdenum/ZTO thin film transistors.

  11. Structural and morphological properties of mesoporous carbon coated molybdenum oxide films

    SciTech Connect

    Dayal, Saurabh Kumar, C. Sasi

    2016-05-06

    In the present study, we report the structural and morphological properties of mesoporous carbon coated molybdenum oxide films. The deposition of films was carried out in a two-step process, the first step involves deposition of molybdenum and carbon bilayer thin films using DC magnetron sputtering. In the second step the sample was ex-situ annealed in a muffle furnace at different temperatures (400°C to 600°C) and air cooled in the ambient atmosphere. The formation of the meso-porous carbon clusters on molybdenum oxide during the cooling step was investigated using FESEM and AFM techniques. The structural details were explored using XRD. The meso-porous carbon were found growing over molybdenum oxide layer as a result of segregation phenomena.

  12. Preparation and activation of micro-arc oxidation films on a TLM titanium alloy

    NASA Astrophysics Data System (ADS)

    Yu, S.; Yu, Z. T.

    2008-12-01

    In order to improve the biocompatibility and surface activity of a TLM alloy, a layer of a porous TiO2 film was prepared by the micro-arc oxidation method on the surface, and then the NH-2 active group was introduced on the film by an activation treatment in an aminated solution. The phase identification and surface characteristics of the micro-arc oxidation films were characterized by XRD, XPS, SEM and EDS. The in vitro blood compatibility of the TLM alloy samples with and without surface modification was evaluated by contact angle tests, hemolysis tests and electrochemical tests. The results indicate that the biocompatibility and surface activity of the TLM alloy could be remarkably improved by surface modification of micro-arc oxidation and activation treatment.

  13. Titanium-silicon oxide film structures for polarization-modulated infrared reflection absorption spectroscopy

    PubMed Central

    Dunlop, Iain E.; Zorn, Stefan; Richter, Gunther; Srot, Vesna; Kelsch, Marion; van Aken, Peter A.; Skoda, Maximilian; Gerlach, Alexander; Spatz, Joachim P.; Schreiber, Frank

    2010-01-01

    We present a titanium-silicon oxide film structure that permits polarization modulated infrared reflection absorption spectroscopy on silicon oxide surfaces. The structure consists of a ~6 nm sputtered silicon oxide film on a ~200 nm sputtered titanium film. Characterization using conventional and scanning transmission electron microscopy, electron energy loss spectroscopy, X-ray photoelectron spectroscopy and X-ray reflectometry is presented. We demonstrate the use of this structure to investigate a selectively protein-resistant self-assembled monolayer (SAM) consisting of silane-anchored, biotin-terminated poly(ethylene glycol) (PEG). PEG-associated IR bands were observed. Measurements of protein-characteristic band intensities showed that this SAM adsorbed streptavidin whereas it repelled bovine serum albumin, as had been expected from its structure. PMID:20418963

  14. Oxidation-temperature dependence of the optical properties of ZnO thin films grown on corning glass by oxidation of metallic Zn

    NASA Astrophysics Data System (ADS)

    Park, Seonhee; Nam, Giwoong; Kim, Younggyu; Kim, Byunggu; Park, Youngbin; Lee, Wookbin; Moon, Jiyun; Kim, Dongwan; Kim, Mincheol; Jeon, Woosung; Jeon, Minhyun; Song, Hanjung; Han, Ki-Ho; Sohn, Keun Yong; Lee, Woo-kyoung; Leem, Jae-Young

    2015-10-01

    We investigated the structural and the optical properties of ZnO thin films formed on Corning glass by the oxidation of Zn thin films, which were deposited by using thermal evaporation and were then oxidized at 300 - 600 °C. The grain size of the ZnO thin films increased and the grains became more densely packed with increasing oxidation temperature. In the photoluminescence (PL) spectra of the ZnO thin films, the intensity of the near-band-edge peak increased with increasing temperature to 500 °C, but decreased gradually with further increases in the temperature. The transmittances of the ZnO thin films formed by oxidation at 400 and 500 °C were higher than 85% in the visible-light region. Finally, the Urbach energy decreased significantly and the optical band gap exhibited a blue shift with increasing oxidation temperature from 300 to 400 °C.

  15. Low temperature atmospheric pressure chemical vapor deposition of group 14 oxide films

    SciTech Connect

    Hoffman, D.M.; Atagi, L.M. |; Chu, Wei-Kan; Liu, Jia-Rui; Zheng, Zongshuang; Rubiano, R.R.; Springer, R.W.; Smith, D.C.

    1994-06-01

    Depositions of high quality SiO{sub 2} and SnO{sub 2} films from the reaction of homoleptic amido precursors M(NMe{sub 2})4 (M = Si,Sn) and oxygen were carried out in an atmospheric pressure chemical vapor deposition r. The films were deposited on silicon, glass and quartz substrates at temperatures of 250 to 450C. The silicon dioxide films are stoichiometric (O/Si = 2.0) with less than 0.2 atom % C and 0.3 atom % N and have hydrogen contents of 9 {plus_minus} 5 atom %. They are deposited with growth rates from 380 to 900 {angstrom}/min. The refractive indexes of the SiO{sub 2} films are 1.46, and infrared spectra show a possible Si-OH peak at 950 cm{sup {minus}1}. X-Ray diffraction studies reveal that the SiO{sub 2} film deposited at 350C is amorphous. The tin oxide films are stoichiometric (O/Sn = 2.0) and contain less than 0.8 atom % carbon, and 0.3 atom % N. No hydrogen was detected by elastic recoil spectroscopy. The band gap for the SnO{sub 2} films, as estimated from transmission spectra, is 3.9 eV. The resistivities of the tin oxide films are in the range 10{sup {minus}2} to 10{sup {minus}3} {Omega}cm and do not vary significantly with deposition temperature. The tin oxide film deposited at 350C is cassitterite with some (101) orientation.

  16. Facile synthesis of cobalt-doped zinc oxide thin films for highly efficient visible light photocatalysts

    NASA Astrophysics Data System (ADS)

    Altintas Yildirim, Ozlem; Arslan, Hanife; Sönmezoğlu, Savaş

    2016-12-01

    Cobalt-doped zinc oxide (Co:ZnO) thin films with dopant contents ranging from 0 to 5 at.% were prepared using the sol-gel method, and their structural, morphological, optical, and photocatalytic properties were characterized. The effect of the dopant content on the photocatalytic properties of the films was investigated by examining the degradation behavior of methylene blue (MB) under visible light irradiation, and a detailed investigation of their photocatalytic activities was performed by determining the apparent quantum yields (AQYs). Co2+ ions were observed to be substitutionally incorporated into Zn2+ sites in the ZnO crystal, leading to lattice parameter constriction and band gap narrowing due to the photoinduced carriers produced under the visible light irradiation. Thus, the light absorption range of the Co:ZnO films was improved compared with that of the undoped ZnO film, and the Co:ZnO films exhibited highly efficient photocatalytic activity (∼92% decomposition of MB after 60-min visible light irradiation for the 3 at.% Co:ZnO film). The AQYs of the Co:ZnO films were greatly enhanced under visible light irradiation compared with that of the undoped ZnO thin film, demonstrating the effect of the Co doping level on the photocatalytic activity of the films.

  17. Tailoring of absorption edge by thermal annealing in tin oxide thin films

    SciTech Connect

    Thakur, Anup; Gautam, Sanjeev; Kumar, Virender; Chae, K. H.; Lee, Ik-Jae; Shin, Hyun Joon

    2015-05-15

    Tin oxide (SnO{sub 2}) thin films were deposited by radio-frequency (RF) magnetron sputtering on silicon and glass substrates in different oxygen-to-argon gas-flow ratio (O{sub 2}-to-Ar = 0%, 10%, 50%). All films were deposited at room temperature and fixed working pressures, 10 mTorr. The X-ray diffraction (XRD) measurement suggests that all films were crystalline in nature except film deposited in argon environment. Thin films were annealed in air at 200 °C, 400 °C and 600 °C for two hours. All films were highly transparent except the film deposited only in the argon environment. It was also observed that transparency was improved with annealing due to decrease in oxygen vacancies. Atomic force microscopy (AFM), results showed that the surface of all the films were highly flat and smooth. Blue shift was observed in the absorption edge with annealing temperature. It was also observed that there was not big change in the absorption edge with annealing for films deposited in 10% and 50% oxygen-to-argon gas-flow ratio.

  18. Solid-phase photocatalytic degradation of polyethylene film with manganese oxide OMS-2

    NASA Astrophysics Data System (ADS)

    Liu, Guanglong; Liao, Shuijiao; Zhu, Duanwei; Cui, Jingzhen; Zhou, Wenbing

    2011-01-01

    Solid-phase photocatalytic degradation of polyethylene (PE) film with cryptomelane-type manganese oxide (OMS-2) as photocatalyst was investigated in the ambient air under ultraviolet and visible light irradiation. The properties of the composite films were compared with those of the pure PE film through performing weight loss monitoring, IR spectroscopy, scanning electron microscopic (SEM) and X-ray photoelectron spectroscopy (XPS). The photoinduced degradation of PE-OMS-2 composite films was higher than that of the pure films, while there has been little change under the visible light irradiation. The weight loss of PE-OMS-2 (1.0 wt%) composite films steadily decreased and reached 16.5% in 288 h under UV light irradiation. Through SEM observation there were some cavities on the surface of composite films, but few change except some surface chalking phenomenon occurred in pure PE film. The degradation rate with ultraviolet irradiation is controllable by adjusting the content of OMS-2 particles in PE plastic. Finally, the mechanism of photocatalytic degradation of the composite films was briefly discussed.

  19. Vanadium Oxide Thin Films Alloyed with Ti, Zr, Nb, and Mo for Uncooled Infrared Imaging Applications

    NASA Astrophysics Data System (ADS)

    Ozcelik, Adem; Cabarcos, Orlando; Allara, David L.; Horn, Mark W.

    2013-05-01

    Microbolometer-grade vanadium oxide (VO x ) thin films with 1.3 < x < 2.0 were prepared by pulsed direct-current (DC) sputtering using substrate bias in a controlled oxygen and argon environment. These films were systematically alloyed with Ti, Nb, Mo, and Zr using a second gun and radiofrequency (RF) reactive co-sputtering to probe the effects of the transition metals on the film charge transport characteristics. The results reveal that the temperature coefficient of resistance (TCR) and resistivity are unexpectedly similar for alloyed and unalloyed films up to alloy compositions in the ˜20 at.% range. Analysis of the film structures for the case of the 17% Nb-alloyed film by glancing-angle x-ray diffraction and transmission electron microscopy shows that the microstructure remains even with the addition of high concentrations of alloy metal, demonstrating the robust character of the VO x films to maintain favorable electrical transport properties for bolometer applications. Postdeposition thermal annealing of the alloyed VO x films further reveals improvement of electrical properties compared with unalloyed films, indicating a direction for further improvements in the materials.

  20. Formation and stability of lanthanum oxide thin films deposited from β-diketonate precursor

    NASA Astrophysics Data System (ADS)

    Nieminen, Minna; Putkonen, Matti; Niinistö, Lauri

    2001-04-01

    Lanthanum oxide thin film deposition by atomic layer epitaxy (ALE) was studied at 180-425°C on soda-lime glass and Si(1 0 0) substrates using a β-diketonate type precursor La(thd) 3 and ozone. The chemical constituents of the films were analyzed by TOF-ERDA, RBS and FTIR while XRD and AFM were used to determine the crystallinity and surface morphology. Films grown below 275°C were amorphous La 2O 2CO 3, while at deposition temperatures above 300°C XRD patterns indicated that cubic La 2O 3 phase was formed. All the films were transparent and uniform with only small thickness variations. Carbonate type impurity was found in all films, but the carbon content of the films decreased with growth temperature being 3 at.% in films grown above 400°C. Hexagonal La 2O 3 was obtained when the films grown on silicon substrates were annealed at 800°C or above in a nitrogen flow. The as-deposited cubic and annealed hexagonal La 2O 3 films were found to be chemically unstable in ambient air since a transformation to monoclinic LaO(OH) and hexagonal La(OH) 3 was detected, respectively.