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Sample records for hafnium oxide film

  1. Amorphous Hafnium-Indium-Zinc Oxide Semiconductor Thin Film Transistors

    Directory of Open Access Journals (Sweden)

    Sheng-Po Chang

    2012-01-01

    Full Text Available We reported on the performance and electrical properties of co-sputtering-processed amorphous hafnium-indium-zinc oxide (α-HfIZO thin film transistors (TFTs. Co-sputtering-processed α-HfIZO thin films have shown an amorphous phase in nature. We could modulate the In, Hf, and Zn components by changing the co-sputtering power. Additionally, the chemical composition of α-HfIZO had a significant effect on reliability, hysteresis, field-effect mobility (μFE, carrier concentration, and subthreshold swing (S of the device. Our results indicated that we could successfully and easily fabricate α-HfIZO TFTs with excellent performance by the co-sputtering process. Co-sputtering-processed α-HfIZO TFTs were fabricated with an on/off current ratio of ~106, higher mobility, and a subthreshold slope as steep as 0.55 V/dec.

  2. Oxidation Effect in Octahedral Hafnium Disulfide Thin Film.

    Science.gov (United States)

    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.

  3. Synthesis and characterization of hafnium oxide films for thermo and photoluminescence applications.

    Science.gov (United States)

    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.

  4. Thin Films of Reduced Hafnium Oxide with Excess Carbon for High-Temperature Oxidation Protection

    Science.gov (United States)

    2010-02-01

    contamination; thus the higher oxygen content found by XPS is partly due to organic impurities (and, possibly, water ) that are mostly concentrated in the...International Service Award, 2007. 25 REFERENCES ’C. B. Bargeron, R. C. Benson, and A. N. Jette , "High-Temperature Diffusion of Oxygen in Oxidizing Hafnium...A. N. Jette , and T. E. Phillips, "Oxidation of Hafnium Carbide in the Temperature Range 1400 ° to 2060 °C," Journal of the American Ceramic Society

  5. Highly flexible resistive switching memory based on amorphous-nanocrystalline hafnium oxide films.

    Science.gov (United States)

    Shang, Jie; Xue, Wuhong; Ji, Zhenghui; Liu, Gang; Niu, Xuhong; Yi, Xiaohui; Pan, Liang; Zhan, Qingfeng; Xu, Xiao-Hong; Li, Run-Wei

    2017-06-01

    Flexible and transparent resistive switching memories are highly desired for the construction of portable and even wearable electronics. Upon optimization of the microstructure wherein an amorphous-nanocrystalline hafnium oxide thin film is fabricated, an all-oxide based transparent RRAM device with stable resistive switching behavior that can withstand a mechanical tensile stress of up to 2.12% is obtained. It is demonstrated that the superior electrical, thermal and mechanical performance of the ITO/HfOx/ITO device can be ascribed to the formation of pseudo-straight metallic hafnium conductive filaments in the switching layer, and is only limited by the choice of electrode materials. When the ITO bottom electrode is replaced with platinum metal, the mechanical failure threshold of the device can be further extended.

  6. Compositional analysis of polycrystalline hafnium oxide thin films by heavy-ion elastic recoil detection analysis

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, F.L. [Departamento de Electronica y Tecnologia de Computadoras, Universidad Politecnica de Cartagena, Campus Universitario Muralla del Mar, E-30202 Cartagena (Spain)]. E-mail: Felix.Martinez@upct.es; Toledano, M. [Departamento de Fisica Aplicada III, Universidad Complutense de Madrid, E-28025 Madrid (Spain); San Andres, E. [Departamento de Fisica Aplicada III, Universidad Complutense de Madrid, E-28025 Madrid (Spain); Martil, I. [Departamento de Fisica Aplicada III, Universidad Complutense de Madrid, E-28025 Madrid (Spain); Gonzalez-Diaz, G. [Departamento de Fisica Aplicada III, Universidad Complutense de Madrid, E-28025 Madrid (Spain); Bohne, W. [Hahn-Meitner-Institut Berlin, Abteilung SF-4, D-14109 Berlin (Germany); Roehrich, J. [Hahn-Meitner-Institut Berlin, Abteilung SF-4, D-14109 Berlin (Germany); Strub, E. [Hahn-Meitner-Institut Berlin, Abteilung SF-4, D-14109 Berlin (Germany)

    2006-10-25

    The composition of polycrystalline hafnium oxide thin films has been measured by heavy-ion elastic recoil detection analysis (HI-ERDA). The films were deposited by high-pressure reactive sputtering (HPRS) on silicon wafers using an oxygen plasma at pressures between 0.8 and 1.6 mbar and during deposition times between 0.5 and 3.0 h. Hydrogen was found to be the main impurity and its concentration increased with deposition pressure. The composition was always slightly oxygen-rich, which is attributed to the oxygen plasma. Additionally, an interfacial silicon oxide thin layer was detected and taken into account. The thickness of the hafnium oxide film was found to increase linearly with deposition time and to decrease exponentially with deposition pressure, whereas the thickness of the silicon oxide interfacial layer has a minimum as a function of pressure at around 1.2 mbar and increases slightly as a function of time. The measurements confirmed that this interfacial layer is formed mainly during the early stages of the deposition process.

  7. Pyroelectric response in crystalline hafnium zirconium oxide (Hf1-xZrxO2) thin films

    Science.gov (United States)

    Smith, S. W.; Kitahara, A. R.; Rodriguez, M. A.; Henry, M. D.; Brumbach, M. T.; Ihlefeld, J. F.

    2017-02-01

    Pyroelectric coefficients were measured for 20 nm thick crystalline hafnium zirconium oxide (Hf1-xZrxO2) thin films across a composition range of 0 ≤ x ≤ 1. Pyroelectric currents were collected near room temperature under zero applied bias and a sinusoidal oscillating temperature profile to separate the influence of non-pyroelectric currents. The pyroelectric coefficient was observed to correlate with zirconium content, increased orthorhombic/tetragonal phase content, and maximum polarization response. The largest measured absolute value was 48 μCm-2 K-1 for a composition with x = 0.64, while no pyroelectric response was measured for compositions which displayed no remanent polarization (x = 0, 0.91, and 1).

  8. Fatigue mechanism of yttrium-doped hafnium oxide ferroelectric thin films fabricated by pulsed laser deposition.

    Science.gov (United States)

    Huang, Fei; Chen, Xing; Liang, Xiao; Qin, Jun; Zhang, Yan; Huang, Taixing; Wang, Zhuo; Peng, Bo; Zhou, Peiheng; Lu, Haipeng; Zhang, Li; Deng, Longjiang; Liu, Ming; Liu, Qi; Tian, He; Bi, Lei

    2017-02-01

    Owing to their prominent stability and CMOS compatibility, HfO2-based ferroelectric films have attracted great attention as promising candidates for ferroelectric random-access memory applications. A major reliability issue for HfO2 based ferroelectric devices is fatigue. So far, there have been a few studies on the fatigue mechanism of this material. Here, we report a systematic study of the fatigue mechanism of yttrium-doped hafnium oxide (HYO) ferroelectric thin films deposited by pulsed laser deposition. The influence of pulse width, pulse amplitude and temperature on the fatigue behavior of HYO during field cycling is studied. The temperature dependent conduction mechanism is characterized after different fatigue cycles. Domain wall pinning caused by carrier injection at shallow defect centers is found to be the major fatigue mechanism of this material. The fatigued device can fully recover to the fatigue-free state after being heated at 90 °C for 30 min, confirming the shallow trap characteristic of the domain wall pinning defects.

  9. Silicon-doped hafnium oxide anti-ferroelectric thin films for energy storage

    Science.gov (United States)

    Ali, Faizan; Liu, Xiaohua; Zhou, Dayu; Yang, Xirui; Xu, Jin; Schenk, Tony; Müller, Johannes; Schroeder, Uwe; Cao, Fei; Dong, Xianlin

    2017-10-01

    Motivated by the development of ultracompact electronic devices as miniaturized energy autonomous systems, great research efforts have been expended in recent years to develop various types of nano-structural energy storage components. The electrostatic capacitors characterized by high power density are competitive; however, their implementation in practical devices is limited by the low intrinsic energy storage density (ESD) of linear dielectrics like Al2O3. In this work, a detailed experimental investigation of energy storage properties is presented for 10 nm thick silicon-doped hafnium oxide anti-ferroelectric thin films. Owing to high field induced polarization and slim double hysteresis, an extremely large ESD value of 61.2 J/cm3 is achieved at 4.5 MV/cm with a high efficiency of ˜65%. In addition, the ESD and the efficiency exhibit robust thermal stability in 210-400 K temperature range and an excellent endurance up to 109 times of charge/discharge cycling at a very high electric field of 4.0 MV/cm. The superior energy storage performance together with mature technology of integration into 3-D arrays suggests great promise for this recently discovered anti-ferroelectric material to replace the currently adopted Al2O3 in fabrication of nano-structural supercapacitors.

  10. Facing-target mid-frequency magnetron reactive sputtered hafnium oxide film: Morphology and electrical properties

    Science.gov (United States)

    Zhang, Yu; Xu, Jun; Wang, You-Nian; Choi, Chi Kyu; Zhou, Da-Yu

    2016-03-01

    Amorphous hafnium dioxide (HfO2) film was prepared on Si (100) by facing-target mid-frequency reactive magnetron sputtering under different oxygen/argon gas ratio at room temperature with high purity Hf target. 3D surface profiler results showed that the deposition rates of HfO2 thin film under different O2/Ar gas ratio remain unchanged, indicating that the facing target midfrequency magnetron sputtering system provides effective approach to eliminate target poisoning phenomenon which is generally occurred in reactive sputtering procedure. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) demonstrated that the gradual reduction of oxygen vacancy concentration and the densification of deposited film structure with the increase of oxygen/argon (O2/Ar) gas flow ratio. Atomic force microscopy (AFM) analysis suggested that the surface of the as-deposited HfO2 thin film tends to be smoother, the root-meansquare roughness (RMS) reduced from 0.876 nm to 0.333 nm while O2/Ar gas flow ratio increased from 1/4 to 1/1. Current-Voltage measurements of MOS capacitor based on Au/HfO2/Si structure indicated that the leakage current density of HfO2 thin films decreased by increasing of oxygen partial pressure, which resulted in the variations of pore size and oxygen vacancy concentration in deposited thin films. Based on the above characterization results the leakage current mechanism for all samples was discussed systematically.

  11. Formulation and method for preparing gels comprising hydrous hafnium oxide

    Science.gov (United States)

    Collins, Jack L; Hunt, Rodney D; Montgomery, Frederick C

    2013-08-06

    Formulations useful for preparing hydrous hafnium oxide gels contain a metal salt including hafnium, an acid, an organic base, and a complexing agent. Methods for preparing gels containing hydrous hafnium oxide include heating a formulation to a temperature sufficient to induce gel formation, where the formulation contains a metal salt including hafnium, an acid, an organic base, and a complexing agent.

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

    Science.gov (United States)

    2014-09-01

    to derive a comprehensive understanding of the structure and optical properties of HfO2 thin films grown as a function of variable deposition...2.2.5. Spectrophotometry measurements Optical properties were evaluated using both spectrophoto- metric and ellipsometry measurements. Spectrophotometry ...reflection or critical edge, while film thickness can be derived from the period of the oscillations in the XRR spectra. In the present case, it is evident

  13. Formation and control of stoichiometric hafnium nitride thin films by direct sputtering of hafnium nitride target

    CERN Document Server

    Gotoh, Y; Ishikawa, J; Liao, M Y

    2003-01-01

    Hafnium nitride thin films were prepared by radio-frequency sputter deposition with a hafnium nitride target. Deposition was performed with various rf powers, argon pressures, and substrate temperatures, in order to investigate the influences of these parameters on the film properties, particularly the nitrogen composition. It was found that stoichiometric hafnium nitride films were formed at an argon gas pressure of less than 2 Pa, irrespective of the other deposition parameters within the range investigated. Maintaining the nitrogen composition almost stoichiometric, orientation, stress, and electrical resistivity of the films could be controlled with deposition parameters. (author)

  14. The Rayleigh law in silicon doped hafnium oxide ferroelectric thin films

    Energy Technology Data Exchange (ETDEWEB)

    Guan, Yan; Liu, Xiaohua [Key Laboratory of Materials Modification by Laser, Ion, and Electron Beams (Ministry of Education), School of Materials Science and Engineering, Dalian University of Technology, Dalian (China); Zhou, Dayu [Key Laboratory of Materials Modification by Laser, Ion, and Electron Beams (Ministry of Education), School of Materials Science and Engineering, Dalian University of Technology, Dalian (China); State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu (China); Xu, Jin [Department of Electronic Engineering, Dalian Neusoft University of Information, Dalian (China); Cao, Fei; Dong, Xianlin [Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai (China); Mueller, Johannes [Fraunhofer IPMS-CNT, Dresden (Germany); Schenk, Tony; Schroeder, Uwe [NaMLab gGmbH/TU Dresden (Germany)

    2015-10-15

    A wealth of studies have confirmed that the low-field hysteresis behaviour of ferroelectric bulk ceramics and thin films can be described using Rayleigh relations, and irreversible domain wall motion across the array of pining defects has been commonly accepted as the underlying micro-mechanism. Recently, HfO{sub 2} thin films incorporated with various dopants were reported to show pronounced ferroelectricity, however, their microscopic domain structure remains unclear till now. In this work, the effects of the applied electric field amplitude, frequency and temperature on the sub-coercive polarization reversal properties were investigated for 10 nm thick Si-doped HfO{sub 2} thin films. The applicability of the Rayleigh law to ultra-thin ferroelectric films was first confirmed, indicating the existence of a multi-domain structure. Since the grain size is about 20-30 nm, a direct observation of domain walls within the grains is rather challenging and this indirect method is a feasible approach to resolve the domain structure. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Effects of oxygen partial pressure and annealing temperature on the residual stress of hafnium oxide thin-films on silicon using synchrotron-based grazing incidence X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Biswas, Debaleen [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064 (India); Sinha, Anil Kumar [ISU, Raja Ramanna Centre for Advanced Technology, Indore 452 013 (India); Homi Bhabha National Institute, BARC, Mumbai 400 094 (India); Chakraborty, Supratic, E-mail: supratic.chakraborty@saha.ac.in [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064 (India)

    2016-10-30

    Highlights: • Residual stress estimation thin hafnium oxide film with thickness of <10 nm. • A mathematical expression is proposed for stress estimation of thin-film using GIXRD. • Residual stress varies with argon content in Ar/O{sub 2} plasma and annealing temperature. • Variation of stress is explained by IL swelling and enhanced structural relaxation. - Abstract: Synchrotron radiation-based grazing incidence X-ray diffraction (GI-XRD) technique is employed here to estimate the residual stress of < 10 nm thin hafnium oxide film deposited on Si (100) substrate at different argon/oxygen ratios using reactive rf sputtering. A decrease in residual stress, tensile in nature, is observed at higher annealing temperature for the samples deposited with increasing argon ratio in the Ar/O{sub 2} plasma. The residual stress of the films deposited at higher p{sub Ar} (Ar:O{sub 2} = 4:1) is also found to be decreased with increasing annealing temperature. But the stress is more or less constant with annealing temperature for the films deposited at lower Ar/O{sub 2} (1:4) ratio. All the above phenomena can be explained on the basis of swelling of the interfacial layer and enhanced structural relaxation in the presence of excess Hf in hafnium oxide film during deposition.

  16. Percolation conductivity in hafnium sub-oxides

    Energy Technology Data Exchange (ETDEWEB)

    Islamov, D. R., E-mail: damir@isp.nsc.ru; Gritsenko, V. A., E-mail: grits@isp.nsc.ru [Rzhanov Institute of Semiconductor Physics, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Cheng, C. H. [Department of Mechatronic Technology, National Taiwan Normal University, Taipei 106, Taiwan (China); Chin, A., E-mail: albert-achin@hotmail.com [National Chiao Tung University, Hsinchu 300, Taiwan (China)

    2014-12-29

    In this study, we demonstrated experimentally that formation of chains and islands of oxygen vacancies in hafnium sub-oxides (HfO{sub x}, x < 2) leads to percolation charge transport in such dielectrics. Basing on the model of Éfros-Shklovskii percolation theory, good quantitative agreement between the experimental and theoretical data of current-voltage characteristics was achieved. Based on the percolation theory suggested model shows that hafnium sub-oxides consist of mixtures of metallic Hf nanoscale clusters of 1–2 nm distributed onto non-stoichiometric HfO{sub x}. It was shown that reported approach might describe low resistance state current-voltage characteristics of resistive memory elements based on HfO{sub x}.

  17. Nanoscale radiotherapy with hafnium oxide nanoparticles.

    Science.gov (United States)

    Maggiorella, Laurence; Barouch, Gilles; Devaux, Corinne; Pottier, Agnès; Deutsch, Eric; Bourhis, Jean; Borghi, Elsa; Levy, Laurent

    2012-09-01

    There is considerable interest in approaches that could improve the therapeutic window of radiotherapy. In this study, hafnium oxide nanoparticles were designed that concentrate in tumor cells to achieve intracellular high-energy dose deposit. Conventional methods were used, implemented in different ways, to explore interactions of these high-atomic-number nanoparticles and ionizing radiation with biological systems. Using the Monte Carlo simulation, these nanoparticles, when exposed to high-energy photons, were shown to demonstrate an approximately ninefold radiation dose enhancement compared with water. Importantly, the nanoparticles show satisfactory dispersion and persistence within the tumor and they form clusters in the cytoplasm of cancer cells. Marked antitumor activity is demonstrated in human cancer models. Safety is similar in treated and control animals as demonstrated by a broad program of toxicology evaluation. These findings, supported by good tolerance, provide the basis for developing this new type of nanoparticle as a promising anticancer approach in human patients.

  18. Physical mechanism of refractive index inhomogeneity of hafnium oxide thin film prepared by ion beam sputtering technique

    Science.gov (United States)

    Liu, Huasong; Wang, Lishuan; Li, Shida; Jiang, Yugang; Liu, Dandan; Yang, Xiao; Ji, Yiqin; Zhang, Feng; Chen, Deying

    2018-01-01

    The HfO2 thin films prepared by ion beam sputtering are thinned after heat treatment. The optical constants of the thin films were obtained by inversion of the ellipsometric parameters. The crystal structure of the films was characterized by X-ray diffractometer. The results show that the correlation coefficient between the refractive index and the grain size is more than 90%. The refractive index increases with the increase of the grain size. The physical mechanism of the refractive index inhomogeneity in the film thickness direction is crystallization of thin films.

  19. Hardness, elastic modulus, and wear resistance of hafnium oxide-based films grown by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Berdova, Maria; Liu, Xuwen; Franssila, Sami, E-mail: sami.franssila@aalto.fi [Department of Materials Science and Engineering, Aalto University, 02150 Espoo (Finland); Wiemer, Claudia; Lamperti, Alessio; Tallarida, Grazia; Cianci, Elena [Laboratorio MDM, IMM CNR, Via C. Olivetti 2, 20864 Agrate Brianza (MB) (Italy); Fanciulli, Marco [Laboratorio MDM, IMM CNR, Via C. Olivetti 2, 20864 Agrate Brianza (MB), Italy and Dipartimento di Scienza dei Materiali, Università degli studi di Milano Bicocca, 20126 Milano (Italy)

    2016-09-15

    The investigation of mechanical properties of atomic layer deposition HfO{sub 2} films is important for implementing these layers in microdevices. The mechanical properties of films change as a function of composition and structure, which accordingly vary with deposition temperature and post-annealing. This work describes elastic modulus, hardness, and wear resistance of as-grown and annealed HfO{sub 2}. From nanoindentation measurements, the elastic modulus and hardness remained relatively stable in the range of 163–165 GPa and 8.3–9.7 GPa as a function of deposition temperature. The annealing of HfO{sub 2} caused significant increase in hardness up to 14.4 GPa due to film crystallization and densification. The structural change also caused increase in the elastic modulus up to 197 GPa. Wear resistance did not change as a function of deposition temperature, but improved upon annealing.

  20. High-performance printed carbon nanotube thin-film transistors array fabricated by a nonlithography technique using hafnium oxide passivation layer and mask.

    Science.gov (United States)

    Pillai, Suresh Kumar Raman; Chan-Park, Mary B

    2012-12-01

    The large-scale application of semiconducting single-walled carbon nanotubes (s-SWCNTs) for printed electronics requires scalable, repeateable, as well as noncontaminating assembly techniques. Previously explored nanotube deposition methods include serial methods such as inkjet printing and parallel methods such as spin-coating with photolithography. The serial methods are usually slow, whereas the photolithography-related parallel methods result in contamination of the nanotubes. In this paper, we report a reliable clean parallel method for fabrication of arrays of carbon nanotube-based field effect transistors (CNTFETs) involving shadow mask patterning of a passivating layer of Hafnium oxide (HfO(2)) over the nanotube (CNT) active channel regions and plasma etching of the unprotected nanotubes. Pure (99%) semiconducting SWCNTs are first sprayed over the entire surface of a wafer substrate followed by a two-step shadow masking procedure to first deposit metal electrodes and then a HfO(2) isolation/passivation layer over the device channel region. The exposed SWCNT network outside the HfO(2) protected area is removed with oxygen plasma etching. The HfO(2) thus serves as both the device isolation mask during the plasma etching and as a protective passivating layer in subsequent use. The fabricated devices on SiO(2)/Si substrate exhibit good device performance metrics, with on/off ratio ranging from 1 × 10(1) to 3 × 10(5) and mobilities of 4 to 23 cm(2)/(V s). The HfO(2)/Si devices show excellent performance with on/off ratios of 1 × 10(2) to 2 × 10(4) and mobilities of 8 to 56 cm(2)/(V s). The optimum devices (on HfO(2)/Si) have an on/off ratio of 1 × 10(4) and mobility as high as 46 cm(2)/(V s). This HfO(2)-based patterning method enables large scale fabrication of CNTFETs with no resist residue or other contamination on the device channel. Further, shadow masking circumvents the need for expensive and area-limited lithography patterning process. The device

  1. Reduction of the interfacial trap density of indium-oxide thin film transistors by incorporation of hafnium and annealing process

    Directory of Open Access Journals (Sweden)

    Meng-Fang Lin

    2015-01-01

    Full Text Available The stable operation of transistors under a positive bias stress (PBS is achieved using Hf incorporated into InOx-based thin films processed at relatively low temperatures (150 to 250 °C. The mobilities of the Hf-InOx thin-film transistors (TFTs are higher than 8 cm2/Vs. The TFTs not only have negligible degradation in the mobility and a small shift in the threshold voltage under PBS for 60 h, but they are also thermally stable at 85 °C in air, without the need for a passivation layer. The Hf-InOx TFT can be stable even annealed at 150 °C for positive bias temperature stability (PBTS. A higher stability is achieved by annealing the TFTs at 250 °C, originating from a reduction in the trap density at the Hf-InOx/gate insulator interface. The knowledge obtained here will aid in the realization of stable TFTs processed at low temperatures.

  2. Standard specification for nuclear-grade hafnium oxide powder

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This specification defines the physical and chemical requirements for hafnium oxide powder intended for fabrication into shapes for use in a nuclear reactor core. 1.2 The material described herein shall be particulate in nature. 1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

  3. Study on the formation of self-assembled monolayers on sol-gel processed hafnium oxide as dielectric layers.

    Science.gov (United States)

    Ting, Guy G; Acton, Orb; Ma, Hong; Ka, Jae Won; Jen, Alex K-Y

    2009-02-17

    High dielectric constant (k) metal oxides such as hafnium oxide (HfO2) have gained significant interest due to their applications in microelectronics. In order to study and control the surface properties of hafnium oxide, self-assembled monolayers (SAMs) of four different long aliphatic molecules with binding groups of phosphonic acid, carboxylic acid, and catechol were formed and characterized. Surface modification was performed to improve the interface between metal oxide and top deposited materials as well as to create suitable dielectric properties, that is, leakage current and capacitance densities, which are important in organic thin film transistors. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, contact angle goniometry, atomic force microscopy (AFM), and simple metal-HfO2-SAM-metal devices were used to characterize the surfaces before and after SAM modification on sol-gel processed hafnium oxide. The alkylphosphonic acid provided the best monolayer formation on sol-gel processed hafnium oxide to generate a well-packed, ultrathin dielectric exhibiting a low leakage current density of 2x10(-8) A/cm2 at an applied voltage of -2.0 V and high capacitance density of 0.55 microF/cm2 at 10 kHz. Dialkylcatechol showed similar characteristics and the potential for using the catechol SAMs to modify HfO2 surfaces. In addition, the integration of this alkylphosphonic acid SAM/hafnium oxide hybrid dielectric into pentacene-based thin film transistors yields low-voltage operation within 1.5 V and improved performance over bare hafnium oxide.

  4. Switching Kinetics in Nanoscale Hafnium Oxide Based Ferroelectric Field-Effect Transistors.

    Science.gov (United States)

    Mulaosmanovic, Halid; Ocker, Johannes; Müller, Stefan; Schroeder, Uwe; Müller, Johannes; Polakowski, Patrick; Flachowsky, Stefan; van Bentum, Ralf; Mikolajick, Thomas; Slesazeck, Stefan

    2017-02-01

    The recent discovery of ferroelectricity in thin hafnium oxide films has led to a resurgence of interest in ferroelectric memory devices. Although both experimental and theoretical studies on this new ferroelectric system have been undertaken, much remains to be unveiled regarding its domain landscape and switching kinetics. Here we demonstrate that the switching of single domains can be directly observed in ultrascaled ferroelectric field effect transistors. Using models of ferroelectric domain nucleation we explain the time, field and temperature dependence of polarization reversal. A simple stochastic model is proposed as well, relating nucleation processes to the observed statistical switching behavior. Our results suggest novel opportunities for hafnium oxide based ferroelectrics in nonvolatile memory devices.

  5. X-Ray Photoemission Study of the Oxidation of Hafnium

    Directory of Open Access Journals (Sweden)

    A. R. Chourasia

    2009-01-01

    Full Text Available About 20 Å of hafnium were deposited on silicon substrates using the electron beam evaporation technique. Two types of samples were investigated. In one type, the substrate was kept at the ambient temperature. After the deposition, the substrate temperature was increased to 100, 200, and 300∘C. In the other type, the substrate temperature was held fixed at some value during the deposition. For this type, the substrate temperatures used were 100, 200, 300, 400, 500, 550, and 600∘C. The samples were characterized in situ by the technique of X-ray photoelectron spectroscopy. No trace of elemental hafnium is observed in the deposited overlayer. Also, there is no evidence of any chemical reactivity between the overlayer and the silicon substrate over the temperature range used. The hafnium overlayer shows a mixture of the dioxide and the suboxide. The ratio of the suboxide to dioxide is observed to be more in the first type of samples. The spectral data indicate that hafnium has a strong affinity for oxygen. The overlayer gets completely oxidized to form HfO2 at substrate temperature around 300∘C for the first type of samples and at substrate temperature greater than 550∘C for the second type.

  6. Enrichment/isolation of phosphorylated peptides on hafnium oxide prior to mass spectrometric analysis.

    Science.gov (United States)

    Rivera, José G; Choi, Yong Seok; Vujcic, Stefan; Wood, Troy D; Colón, Luis A

    2009-01-01

    Hafnium oxide (hafnia) exhibits unique enrichment properties towards phosphorylated peptides that are complementary to those of titanium oxide (titania) and zirconium oxide (zirconia) for use with mass spectrometric analysis in the field of proteomics.

  7. A thermally robust and thickness independent ferroelectric phase in laminated hafnium zirconium oxide

    Directory of Open Access Journals (Sweden)

    S. Riedel

    2016-09-01

    Full Text Available Ferroelectric properties in hafnium oxide based thin films have recovered the scaling potential for ferroelectric memories due to their ultra-thin-film- and CMOS-compatibility. However, the variety of physical phenomena connected to ferroelectricity allows a wider range of applications for these materials than ferroelectric memory. Especially mixed HfxZr1-xO2 thin films exhibit a broad compositional range of ferroelectric phase stability and provide the possibility to tailor material properties for multiple applications. Here it is shown that the limited thermal stability and thick-film capability of HfxZr1-xO2 can be overcome by a laminated approach using alumina interlayers.

  8. Slow DNA transport through nanopores in hafnium oxide membranes.

    Science.gov (United States)

    Larkin, Joseph; Henley, Robert; Bell, David C; Cohen-Karni, Tzahi; Rosenstein, Jacob K; Wanunu, Meni

    2013-11-26

    We present a study of double- and single-stranded DNA transport through nanopores fabricated in ultrathin (2-7 nm thick) freestanding hafnium oxide (HfO2) membranes. The high chemical stability of ultrathin HfO2 enables long-lived experiments with 50 000 DNA translocations with no detectable pore expansion. Mean DNA velocities are slower than velocities through comparable silicon nitride pores, providing evidence that HfO2 nanopores have favorable physicochemical interactions with nucleic acids that can be leveraged to slow down DNA in a nanopore.

  9. Hafnium carbamates and ureates: new class of precursors for low-temperature growth of HfO2 thin films.

    Science.gov (United States)

    Pothiraja, Ramasamy; Milanov, Andrian P; Barreca, Davide; Gasparotto, Alberto; Becker, Hans-Werner; Winter, Manuela; Fischer, Roland A; Devi, Anjana

    2009-04-21

    Novel volatile compounds of hafnium, namely tetrakis-N,O-dialkylcarbamato hafnium(iv) [Hf((i)PrNC(O)O(i)Pr)(4)] () and tetrakis-N,N,N'-trialkylureato hafnium(iv) [Hf((i)PrNC(O)N-(Me)Et)(4)] (), have been synthesized through the simple insertion reaction of isopropyl isocyanate into hafnium isopropoxide and hafnium ethylmethylamide, respectively; based on the promising thermal properties, compound has been evaluated as a precursor for metalorganic chemical vapor deposition (MOCVD) of HfO(2) thin films, which resulted in the growth of stoichiometric and crystalline layers with a uniform morphology at temperature as low as 250 degrees C.

  10. Ion induced crystallization and grain growth of hafnium oxide nano-particles in thin-films deposited by radio frequency magnetron sputtering

    Science.gov (United States)

    Dhanunjaya, M.; Khan, S. A.; Pathak, A. P.; Avasthi, D. K.; Nageswara Rao, S. V. S.

    2017-12-01

    We report on the swift heavy ion (SHI) irradiation induced crystallization and grain growth of HfO2 nanoparticles (NPs) within the HfO2 thin-films deposited by radio frequency (RF) magnetron sputtering technique. As grown films consisted of amorphous clusters of non-spherical HfO2 NPs. These amorphous clusters are transformed to crystalline grains under 100 MeV Ag ion irradiation. These crystallites are found to be spherical in shape and are well dispersed within the films. The average size of these crystallites is found to increase with fluence. Pristine and irradiated films have been characterized by high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), grazing incident x-ray diffraction (GIXRD) and photo luminescence (PL) measurements. The PL measurements suggested the existence of different types of oxygen related defects in pristine and irradiated samples. The observed results on crystallization and grain growth under the influence of SHI are explained within the framework of thermal spike model. The results are expected to provide useful information for understanding the electronic excitation induced crystallization of nanoparticles and can lead to useful applications in electronic and photonic devices.

  11. The Influence of Hafnium Doping on Density of States in Zinc Oxide Thin-Film Transistors Deposited via Atomic Layer Deposition.

    Science.gov (United States)

    Ding, Xingwei; Qin, Cunping; Song, Jiantao; Zhang, Jianhua; Jiang, Xueyin; Zhang, Zhilin

    2017-12-01

    Thin-film transistors (TFTs) with atomic layer deposition (ALD) HfZnO (HZO) as channel layer and Al2O3 as gate insulator were successfully fabricated. Compared with ZnO-TFT, the stability of HZO-TFT was obviously improved as Hf doping can suppress the generation of oxygen related defects. The transfer characteristics of TFTs at different temperatures were also investigated, and temperature stability enhancement was observed for the TFT with Hf doping. The density of states (DOS) was calculated based on the experimentally obtained E a, which can explain the experimental observation. A high-field effect mobility of 9.4 cm(2)/Vs, a suitable turn-on voltage of 0.26 V, a high on/off ratio of over 10(7) and a steep sub-threshold swing of 0.3 V/decade were obtained in HZO-TFT. The results showed that temperature stability enhancement in HfZnO thin-film transistors are attributed to the smaller DOS.

  12. Hafnium oxide nanoparticles: toward an in vitro predictive biological effect?

    Science.gov (United States)

    Marill, Julie; Anesary, Naeemunnisa Mohamed; Zhang, Ping; Vivet, Sonia; Borghi, Elsa; Levy, Laurent; Pottier, Agnes

    2014-06-30

    Hafnium oxide, NBTXR3 nanoparticles were designed for high dose energy deposition within cancer cells when exposed to ionizing radiation. The purpose of this study was to assess the possibility of predicting in vitro the biological effect of NBTXR3 nanoparticles when exposed to ionizing radiation. Cellular uptake of NBTXR3 nanoparticles was assessed in a panel of human cancer cell lines (radioresistant and radiosensitive) by transmission electron microscopy. The radioenhancement of NBTXR3 nanoparticles was measured by the clonogenic survival assay. NBTXR3 nanoparticles were taken up by cells in a concentration dependent manner, forming clusters in the cytoplasm. Differential nanoparticle uptake was observed between epithelial and mesenchymal or glioblastoma cell lines. The dose enhancement factor increased with increase NBTXR3 nanoparticle concentration and radiation dose. Beyond a minimum number of clusters per cell, the radioenhancement of NBTXR3 nanoparticles could be estimated from the radiation dose delivered and the radiosensitivity of the cancer cell lines. Our preliminary results suggest a predictable in vitro biological effect of NBTXR3 nanoparticles exposed to ionizing radiation.

  13. Cytotoxicity and physicochemical properties of hafnium oxide nanoparticles.

    Science.gov (United States)

    Field, James A; Luna-Velasco, Antonia; Boitano, Scott A; Shadman, Farhang; Ratner, Buddy D; Barnes, Chris; Sierra-Alvarez, Reyes

    2011-09-01

    Nano-sized hafnium oxide (HfO(2)) particles are being considered for applications within the semiconductor industry. However, little is known about their cytotoxicity. The objective of this work was to assess several HfO(2) nanoparticles (NPs) samples for their acute cytotoxicity. Dynamic light scattering analysis of the samples indicated that the average particle size of the HfO(2) in aqueous dispersions was in the submicron range with a fraction of particles having nano-dimensions. The media used in the toxicity assays decreased or increased the average particle size of HfO(2) NPs due to dispersion or agglomeration. Static time-of-flight secondary ion mass spectrometry (ToF-SIMS) revealed numerous surface contaminants on the NPs. Only one HfO(2) sample caused moderate cytotoxicity to human cell lines. The inhibitory sample caused a 50% response in the Live/Dead assay with HaCaT skin cells at 2200 mg L(-1); and a 50% response in the mitochondrial toxicity test at 300 mg L(-1). A microbial inhibition assay based on methanogenic activity also revealed that another HFO(2) sample caused moderate inhibition. The difference in toxicity between samples could not be attributed to size. Instead the difference in toxicity was likely due to differences in the contaminants of the HfO(2). The ToF-SIMS analysis indicated unique signatures of Br and P in the sample toxic to human cell lines suggesting a distinct synthesis was used for that sample which may have been accompanied by inhibitory impurities. The results taken as a whole indicate that HfO(2) itself is relatively non-toxic. Copyright © 2011 Elsevier Ltd. All rights reserved.

  14. Carrier Transport at Metal/Amorphous Hafnium-Indium-Zinc Oxide Interfaces.

    Science.gov (United States)

    Kim, Seoungjun; Gil, Youngun; Choi, Youngran; Kim, Kyoung-Kook; Yun, Hyung Joong; Son, Byoungchul; Choi, Chel-Jong; Kim, Hyunsoo

    2015-10-14

    In this paper, the carrier transport mechanism at the metal/amorphous hafnium-indium-zinc oxide (a-HIZO) interface was investigated. The contact properties were found to be predominantly affected by the degree of interfacial reaction between the metals and a-HIZO; that is, a higher tendency to form metal oxide phases leads to excellent Ohmic contact via tunneling, which is associated with the generated donor-like oxygen vacancies. In this case, the Schottky-Mott theory is not applicable. Meanwhile, metals that do not form interfacial metal oxide, such as Pd, follow the Schottky-Mott theory, which results in rectifying Schottky behavior. The Schottky characteristics of the Pd contact to a-HIZO can be explained in terms of the barrier inhomogeneity model, which yields a mean barrier height of 1.40 eV and a standard deviation of 0.14 eV. The work function of a-HIZO could therefore be estimated as 3.7 eV, which is in good agreement with the ultraviolet photoelectron spectroscopy (3.68 eV). Our findings will be useful for establishing a strategy to form Ohmic or Schottky contacts to a-HIZO films, which will be essential for fabricating reliable high-performance electronic devices.

  15. Hafnium transistor process design for neural interfacing.

    Science.gov (United States)

    Parent, David W; Basham, Eric J

    2009-01-01

    A design methodology is presented that uses 1-D process simulations of Metal Insulator Semiconductor (MIS) structures to design the threshold voltage of hafnium oxide based transistors used for neural recording. The methodology is comprised of 1-D analytical equations for threshold voltage specification, and doping profiles, and 1-D MIS Technical Computer Aided Design (TCAD) to design a process to implement a specific threshold voltage, which minimized simulation time. The process was then verified with a 2-D process/electrical TCAD simulation. Hafnium oxide films (HfO) were grown and characterized for dielectric constant and fixed oxide charge for various annealing temperatures, two important design variables in threshold voltage design.

  16. Microstructure and optical properties of Pr3+-doped hafnium silicate films

    Science.gov (United States)

    2013-01-01

    In this study, we report on the evolution of the microstructure and photoluminescence properties of Pr3+-doped hafnium silicate thin films as a function of annealing temperature (TA). The composition and microstructure of the films were characterized by means of Rutherford backscattering spectrometry, spectroscopic ellipsometry, Fourier transform infrared absorption, and X-ray diffraction, while the emission properties have been studied by means of photoluminescence (PL) and PL excitation (PLE) spectroscopies. It was observed that a post-annealing treatment favors the phase separation in hafnium silicate matrix being more evident at 950°C. The HfO2 phase demonstrates a pronounced crystallization in tetragonal phase upon 950°C annealing. Pr3+ emission appeared at TA = 950°C, and the highest efficiency of Pr3+ ion emission was detected upon a thermal treatment at 1,000°C. Analysis of the PLE spectra reveals an efficient energy transfer from matrix defects towards Pr3+ ions. It is considered that oxygen vacancies act as effective Pr3+ sensitizer. Finally, a PL study of undoped HfO2 and HfSiOx matrices is performed to evidence the energy transfer. PMID:23336520

  17. Electric field cycling behavior of ferroelectric hafnium oxide.

    Science.gov (United States)

    Schenk, Tony; Schroeder, Uwe; Pešić, Milan; Popovici, Mihaela; Pershin, Yuriy V; Mikolajick, Thomas

    2014-11-26

    HfO2 based ferroelectrics are lead-free, simple binary oxides with nonperovskite structure and low permittivity. They just recently started attracting attention of theoretical groups in the fields of ferroelectric memories and electrostatic supercapacitors. A modified approach of harmonic analysis is introduced for temperature-dependent studies of the field cycling behavior and the underlying defect mechanisms. Activation energies for wake-up and fatigue are extracted. Notably, all values are about 100 meV, which is 1 order of magnitude lower than for conventional ferroelectrics like lead zirconate titanate (PZT). This difference is mainly atttributed to the one to two orders of magnitude higher electric fields used for cycling and to the different surface to volume ratios between the 10 nm thin films in this study and the bulk samples of former measurements or simulations. Moreover, a new, analog-like split-up effect of switching peaks by field cycling is discovered and is explained by a network model based on memcapacitive behavior as a result of defect redistribution.

  18. Low-voltage bendable pentacene thin-film transistor with stainless steel substrate and polystyrene-coated hafnium silicate dielectric.

    Science.gov (United States)

    Yun, Dong-Jin; Lee, Seunghyup; Yong, Kijung; Rhee, Shi-Woo

    2012-04-01

    The hafnium silicate and aluminum oxide high-k dielectrics were deposited on stainless steel substrate using atomic layer deposition process and octadecyltrichlorosilane (OTS) and polystyrene (PS) were treated improve crystallinity of pentacene grown on them. Besides, the effects of the pentacene deposition condition on the morphologies, crystallinities and electrical properties of pentacene were characterized. Therefore, the surface treatment condition on dielectric and pentacene deposition conditions were optimized. The pentacene grown on polystyrene coated high-k dielectric at low deposition rate and temperature (0.2-0.3 Å/s and R.T.) showed the largest grain size (0.8-1.0 μm) and highest crystallinity among pentacenes deposited various deposition conditions, and the pentacene TFT with polystyrene coated high-k dielectric showed excellent device-performance. To decrease threshold voltage of pentacene TFT, the polystyrene-thickness on high-k dielectric was controlled using different concentration of polystyrene solution. As the polystyrene-thickness on hafnium silicate decreases, the dielectric constant of polystyrene/hafnium silicate increases, while the crystallinity of pentacene grown on polystyrene/hafnium silicate did not change. Using low-thickness polystyrene coated hafnium silicate dielectric, the high-performance and low voltage operating (1 × 10(4)) and complementary inverter (DC gains, ~20) could be fabricated.

  19. Long period gratings coated with hafnium oxide by plasma-enhanced atomic layer deposition for refractive index measurements.

    Science.gov (United States)

    Melo, Luis; Burton, Geoff; Kubik, Philip; Wild, Peter

    2016-04-04

    Long period gratings (LPGs) are coated with hafnium oxide using plasma-enhanced atomic layer deposition (PEALD) to increase the sensitivity of these devices to the refractive index of the surrounding medium. PEALD allows deposition at low temperatures which reduces thermal degradation of UV-written LPGs. Depositions targeting three different coating thicknesses are investigated: 30 nm, 50 nm and 70 nm. Coating thickness measurements taken by scanning electron microscopy of the optical fibers confirm deposition of uniform coatings. The performance of the coated LPGs shows that deposition of hafnium oxide on LPGs induces two-step transition behavior of the cladding modes.

  20. Optical reflectivity and hardness improvement of hafnium nitride films via tantalum alloying

    Science.gov (United States)

    Gu, Zhiqing; Huang, Haihua; Zhang, Sam; Wang, Xiaoyi; Gao, Jing; Zhao, Lei; Zheng, Weitao; Hu, Chaoquan

    2016-12-01

    It is found that incorporation of tantalum in a hafnium nitride film induces a tunable optical reflectivity and improves the hardness. The underlying mechanism can be illustrated by a combination of experiments and first-principles calculations. It is shown that the evolution of optical reflectivity and the increase in hardness arise from the formation of Hf1-xTaxN solid solutions and the resulting changes in the electronic structure. The increase in infrared reflectance originates from the increase in concentration of free electrons (n) because Ta (d3s2) has one more valence electron than Hf (d2s2). The sharp blue-shift in cutoff wavelength is attributed to the increase in n and the appearance of t2g → eg interband absorption. These results suggest that alloying of a second transition metal renders an effective avenue to improve simultaneously the optical and mechanical properties of transition metal nitride films. This opens up a door in preparing high-reflectance yet hard films.

  1. Complex Internal Bias Fields in Ferroelectric Hafnium Oxide.

    Science.gov (United States)

    Schenk, Tony; Hoffmann, Michael; Ocker, Johannes; Pešić, Milan; Mikolajick, Thomas; Schroeder, Uwe

    2015-09-16

    For the rather new hafnia- and zirconia-based ferroelectrics, a lot of questions are still unsettled. Among them is the electric field cycling behavior consisting of (1) wake-up, (2) fatigue, and (3) the recently discovered subcycling-induced split-up/merging effect of transient current peaks in a hysteresis measurement. In the present work, first-order reversal curves (FORCs) are applied to study the evolution of the switching and backswitching field distribution within the frame of the Preisach model for three different phenomena: (1) The pristine film contains two oppositely biased regions. These internal bias fields vanish during the wake-up cycling. (2) Fatigue as a decrease in the number of switchable domains is accompanied by a slight increase in the mean absolute value of the switching field. (3) The split-up effect is shown to also be related to local bias fields in a complex situation resulting from both the field cycling treatment and the measurement procedure. Moreover, the role of the wake-up phenomenon is discussed with respect to optimizing low-voltage operation conditions of ferroelectric memories toward reasonably high and stable remanent polarization and highest possible endurance.

  2. Initial hafnium oxide growth on silicon(100) and gallium arsenide(100) substrates using TEMAH+water and TDMAH+water ALD processes

    Science.gov (United States)

    Hackley, Justin Cain

    Atomic layer deposition (ALD) is a cyclic growth process that is distinguished by a self-limiting, two-step surface reaction that results in precise growth control and high quality, conformal thin films. Due to the continuous downscaling of MOSFET devices, a large interest has recently developed in the ALD of high-kappa dielectric materials as gate oxide layers on Si and III-V substrates. The ALD of HfO2 is an established process; however, there is still controversy over the initial growth mechanisms on differently prepared Si surfaces. This motivated a comparison of the nucleation stage of HfO 2 films grown on OH-(Si-OH) and H-terminated (Si-H) Si(100) surfaces. Two different ALD chemistries are investigated, including tetrakis[ethylmethylamino]hafnium (Hf[N(CH3)(C2H5)]4), abbreviated as TEMAH, and tetrakis[dimethylamino]hafnium (Hf[N(CH3)2] 4, abbreviated as TDMAH. H2O is used as the oxidizing precursor. Deposition temperatures of 250-275°C result in a linear growth per cycle of 1 A/cycle. Techniques including Rutherford backscattering spectrometry (RBS), X-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometry (SE), and transmission electron microscopy are used to examine the film interface and initial film growth. HfO2 films are also subjected to post-deposition anneals, and the film morphology is examined with X-ray diffraction, Fourier transform infrared spectroscopy and atomic force microscopy. GaAs MOSFET devices have long proven elusive due to the lack of a stable native oxide. Recent research into high-kappa dielectric materials for use in Si-based devices has presented many new options for insulating layers on GaAs. HfO2 growth on GaAs(100) from a TDMAH+H2O ALD process is studied here. Three different GaAs surface treatments are examined, including buffered oxide etch (BOE), NH4OH, and a simple acetone/methanol wash (to retain the native oxide surface). Initial HfO2 growth on these surfaces is characterized with RBS and SE. The interfacial

  3. Multiphonon ionization of traps formed in hafnium oxide by electrical stress

    Energy Technology Data Exchange (ETDEWEB)

    Danilyuk, A.L.; Migas, D.B.; Danilyuk, M.A.; Borisenko, V.E. [Belorussian State University of Informatics and Radioelectronics, P. Browka 6, 220013 Minsk (Belarus); Wu, X.; Pey, K.L. [Microelectronics Center, School of EEE, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore); Concurrently with Engineering Product Development Pillar, Singapore University of Technology and Design, 20 Dover Drive, Singapore 138682 (Singapore); Raghavan, N. [Microelectronics Center, School of EEE, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore)

    2013-02-15

    We have investigated behavior of traps formed in hafnium oxide (HfO{sub 2}) by electrical stress and their influence on the charge carrier transport through Si/SiO{sub 2}/HfO{sub 2}/poly-Si nanostructures. The traps govern the transport process assuming a capture of charge carriers followed by their ionization via the multiphonon transition mechanism. The multiphonon transitions via the Poole-Frenkel effect or electron tunneling as well as the multiphonon tunneling ionization of neutral traps have been carefully considered for charged traps. We also provide a set of parameters including the trap concentration, ionization energy, the frequency factor, the effective mass of charge carriers, optical energy, and phonon energy in order to reproduce and reasonably fit available experimental data. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Surface State Capture Cross-Section at the Interface between Silicon and Hafnium Oxide

    Directory of Open Access Journals (Sweden)

    Fu-Chien Chiu

    2013-01-01

    Full Text Available The interfacial properties between silicon and hafnium oxide (HfO2 are explored by the gated-diode method and the subthreshold measurement. The density of interface-trapped charges, the current induced by surface defect centers, the surface recombination velocity, and the surface state capture cross-section are obtained in this work. Among the interfacial properties, the surface state capture cross-section is approximately constant even if the postdeposition annealing condition is changed. This effective capture cross-section of surface states is about 2.4 × 10−15 cm2, which may be an inherent nature in the HfO2/Si interface.

  5. Conduction Channel Formation and Dissolution Due to Oxygen Thermophoresis/Diffusion in Hafnium Oxide Memristors.

    Science.gov (United States)

    Kumar, Suhas; Wang, Ziwen; Huang, Xiaopeng; Kumari, Niru; Davila, Noraica; Strachan, John Paul; Vine, David; Kilcoyne, A L David; Nishi, Yoshio; Williams, R Stanley

    2016-12-27

    Transition-metal-oxide memristors, or resistive random-access memory (RRAM) switches, are under intense development for storage-class memory because of their favorable operating power, endurance, speed, and density. Their commercial deployment critically depends on predictive compact models based on understanding nanoscale physicochemical forces, which remains elusive and controversial owing to the difficulties in directly observing atomic motions during resistive switching, Here, using scanning transmission synchrotron X-ray spectromicroscopy to study in situ switching of hafnium oxide memristors, we directly observed the formation of a localized oxygen-deficiency-derived conductive channel surrounded by a low-conductivity ring of excess oxygen. Subsequent thermal annealing homogenized the segregated oxygen, resetting the cells toward their as-grown resistance state. We show that the formation and dissolution of the conduction channel are successfully modeled by radial thermophoresis and Fick diffusion of oxygen atoms driven by Joule heating. This confirmation and quantification of two opposing nanoscale radial forces that affect bipolar memristor switching are important components for any future physics-based compact model for the electronic switching of these devices.

  6. Conduction Channel Formation and Dissolution Due to Oxygen Thermophoresis/Diffusion in Hafnium Oxide Memristors

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Suhas; Wang, Ziwen; Huang, Xiaopeng; Kumari, Niru; Davila, Noraica; Strachan, John Paul; Vine, David; Kilcoyne, A. L. David; Nishi, Yoshio; Williams, R. Stanley

    2016-12-27

    Due to the favorable operating power, endurance, speed, and density., transition-metal-oxide memristors, or resistive random-access memory (RRAM) switches, are under intense development for storage-class memory. Their commercial deployment critically depends on predictive compact models based on understanding nanoscale physiocochemical forces, which remains elusive and controversial owing to the difficulties in directly observing atomic motions during resistive switching, Here, using scanning transmission synchrotron X-ray spectromicroscopy to study in situ switching of hafnium oxide memristors, we directly observed the formation of a localized oxygen-deficiency-derived conductive channel surrounded by a low-conductivity ring of excess oxygen. Subsequent thermal annealing homogenized the segregated oxygen, resetting the cells toward their as-grown resistance state. We show that the formation and dissolution of the conduction channel are successfully modeled by radial thermophoresis and Fick diffusion of oxygen atoms driven by Joule heating. This confirmation and quantification of two opposing nanoscale radial forces that affect bipolar memristor switching are important components for any future physics-based compact model for the electronic switching of these devices.

  7. Ferroelectric transistors with monolayer molybdenum disulfide and ultra-thin aluminum-doped hafnium oxide

    Science.gov (United States)

    Yap, Wui Chung; Jiang, Hao; Liu, Jialun; Xia, Qiangfei; Zhu, Wenjuan

    2017-07-01

    In this letter, we demonstrate ferroelectric memory devices with monolayer molybdenum disulfide (MoS2) as the channel material and aluminum (Al)-doped hafnium oxide (HfO2) as the ferroelectric gate dielectric. Metal-ferroelectric-metal capacitors with 16 nm thick Al-doped HfO2 are fabricated, and a remnant polarization of 3 μC/cm2 under a program/erase voltage of 5 V is observed. The capability of potential 10 years data retention was estimated using extrapolation of the experimental data. Ferroelectric transistors based on embedded ferroelectric HfO2 and MoS2 grown by chemical vapor deposition are fabricated. Clockwise hysteresis is observed at low program/erase voltages due to slow bulk traps located near the 2D/dielectric interface, while counterclockwise hysteresis is observed at high program/erase voltages due to ferroelectric polarization. In addition, the endurances of the devices are tested, and the effects associated with ferroelectric materials, such as the wake-up effect and polarization fatigue, are observed. Reliable writing/reading in MoS2/Al-doped HfO2 ferroelectric transistors over 2 × 104 cycles is achieved. This research can potentially lead to advances of two-dimensional (2D) materials in low-power logic and memory applications.

  8. Violet-blue luminescence from hafnium oxide layers doped with CeCl{sub 3} prepared by the spray pyrolysis process

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Hipolito, M.; Alvarez-Fragoso, O.; Alvarez-Perez, M.A.; Martinez-Martinez, R. [Departamento de Materiales Metalicos y Ceramicos, Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico (Mexico); Caldino, U. [Universidad Autonoma Metropolitana, Iztapalapa, Mexico DF (Mexico); Falcony, C. [Departamento de Fisica, CINVESTAV-IPN, Mexico (Mexico)

    2007-07-15

    HfO{sub 2}:CeCl{sub 3} coatings were deposited by the spray pyrolysis method employing hafnium dichloride oxide and CeCl{sub 3} dissolved in deionized water (18 M{omega}/cm). The room temperature photoluminescence characteristics of the HfO{sub 2}:CeCl{sub 3} films were studied as a function of the deposition parameters such as doping concentrations and substrate temperature. The presence of two different Ce{sup 3+} centres in HfO{sub 2} is detected from photoluminescence measurements. A reduction of the luminescence intensity is observed with an increase of both the CeCl{sub 3} concentration and the deposition temperature. X-ray diffraction measurements of these films showed that the crystalline structure depends on the substrate temperature. For substrate temperatures less than 350 C the deposited films are almost amorphous, while substrate temperatures higher than 400 C produce diffraction peaks corresponding to the monoclinic phase of HfO{sub 2}. The chemical composition of the films as determined by energy dispersive spectroscopy is also reported. Furthermore, the surface morphology characteristics of the coatings, as a function of the deposition temperature, are also presented. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. Internal correction of hafnium oxide spectral interferences and mass bias in the determination of platinum in environmental samples using isotope dilution analysis.

    Science.gov (United States)

    Rodríguez-Castrillón, José Angel; Moldovan, Mariella; García Alonso, J Ignacio

    2009-05-01

    A method has been developed for the accurate determination of platinum by isotope dilution analysis, using enriched (194)Pt, in environmental samples containing comparatively high levels of hafnium without any chemical separation. The method is based on the computation of the contribution of hafnium oxide as an independent factor in the observed isotope pattern of platinum in the spiked sample. Under these conditions, the ratio of molar fractions between natural abundance and isotopically enriched platinum was independent of the amount of hafnium present in the sample. Additionally, mass bias was corrected by an internal procedure in which the regression variance was minimised. This was possible as the mass bias factor for hafnium oxide was very close to that of platinum. The final procedure required the measurement of three platinum isotope ratios (192/194, 195/194 and 196/194) to calculate the concentration of platinum in the sample. The methodology has been validated using the reference material "BCR-723 road dust" and has been applied to different environmental matrices (road dust, air particles, bulk wet deposition and epiphytic lichens) collected in the Aspe Valley (Pyrenees Mountains). A full uncertainty budget, using Kragten's spreadsheet method, showed that the total uncertainty was limited only by the uncertainty in the measured isotope ratios and not by the uncertainties of the isotopic composition of platinum and hafnium.

  10. Effects of trimethylaluminium and tetrakis(ethylmethylamino) hafnium in the early stages of the atomic-layer-deposition of aluminum oxide and hafnium oxide on hydroxylated GaN nanoclusters.

    Science.gov (United States)

    León-Plata, Paola A; Coan, Mary R; Seminario, Jorge M

    2013-10-01

    We calculate the interactions of two atomic layer deposition (ALD) reactants, trimethylaluminium (TMA) and tetrakis(ethylmethylamino) hafnium (TEMAH) with the hydroxylated Ga-face of GaN clusters when aluminum oxide and hafnium oxide, respectively, are being deposited. The GaN clusters are suitable as testbeds for the actual Ga-face on practical GaN nanocrystals of importance not only in electronics but for several other applications in nanotechnology. We find that TMA spontaneously interacts with hydroxylated GaN; however it does not follow the atomic layer deposition reaction path unless there is an excess in potential energy introduced in the clusters at the beginning of the optimization, for instance, using larger bond lengths of various bonds in the initial structures. TEMAH also does not interact with hydroxylated GaN, unless there is an excess in potential energy. The formation of a Ga-N(CH3)(CH2CH3) bond during the ALD of HfO2 using TEMAH as the reactant without breaking the Hf-N bond could be the key part of the mechanism behind the formation of an interface layer at the HfO2/GaN interface.

  11. Study of hafnium (IV) oxide nanoparticles synthesized by polymerized complex and polymer precursor derived sol-gel methods

    KAUST Repository

    Ramos-González, R.

    2010-03-01

    This work reports the preparation and characterization of hafnium (IV) oxide (HfO2) nanoparticles grown by derived sol-gel routes that involves the formation of an organic polymeric network. A comparison between polymerized complex (PC) and polymer precursor (PP) methods is presented. For the PC method, citric acid (CA) and ethylene glycol (EG) are used as the chelating and polymerizable reagents, respectively. In the case of PP method, poly(acrylic acid) (PAA) is used as the chelating reagent. In both cases, different precursor gels were prepared and the hafnium (IV) chloride (HfCl4) molar ratio was varied from 0.1 to 1.0 for the PC method and from 0.05 to 0.5 for the PP method. In order to obtain the nanoparticles, the precursors were heat treated at 500 and 800 °C. The thermal characterization of the precursor gels was carried out by thermogravimetric analysis (TGA) and the structural and morphological characterization by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The XRD patterns of the samples obtained by both methods shows the formation of HfO2 at 500 °C with monoclinic crystalline phase. The PC method exhibited also the cubic phase. Finally, the HfO2 nanoparticles size (4 to 11 nm) was determined by TEM and XRD patterns. © (2010) Trans Tech Publications.

  12. Trap state passivation improved hot-carrier instability by zirconium-doping in hafnium oxide in a nanoscale n-metal-oxide semiconductor-field effect transistors with high-k/metal gate

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Hsi-Wen; Tsai, Jyun-Yu; Liu, Kuan-Ju; Lu, Ying-Hsin [Department of Physics, National Sun Yat-sen University, 70 Lien-hai Road, Kaohsiung 80424, Taiwan (China); Chang, Ting-Chang, E-mail: tcchang3708@gmail.com [Department of Physics, National Sun Yat-sen University, 70 Lien-hai Road, Kaohsiung 80424, Taiwan (China); Advanced Optoelectronics Technology Center, National Cheng Kung University, Tainan 701, Taiwan (China); Chen, Ching-En; Tseng, Tseung-Yuen [Department of Electronics Engineering, National Chiao Tung University, Hsinchu 300, Taiwan (China); Lin, Chien-Yu [Department of Photonics, National Sun Yat-Sen University, 70 Lien-hai Road, Kaohsiung 80424, Taiwan (China); Cheng, Osbert; Huang, Cheng-Tung; Ye, Yi-Han [Device Department, United Microelectronics Corporation, Tainan Science Park, Tainan 701, Taiwan (China)

    2016-04-25

    This work investigates the effect on hot carrier degradation (HCD) of doping zirconium into the hafnium oxide high-k layer in the nanoscale high-k/metal gate n-channel metal-oxide-semiconductor field-effect-transistors. Previous n-metal-oxide semiconductor-field effect transistor studies demonstrated that zirconium-doped hafnium oxide reduces charge trapping and improves positive bias temperature instability. In this work, a clear reduction in HCD is observed with zirconium-doped hafnium oxide because channel hot electron (CHE) trapping in pre-existing high-k bulk defects is the main degradation mechanism. However, this reduced HCD became ineffective at ultra-low temperature, since CHE traps in the deeper bulk defects at ultra-low temperature, while zirconium-doping only passivates shallow bulk defects.

  13. Advanced materials for solid oxide fuel cells: Hafnium-Praseodymium-Indium Oxide System

    Energy Technology Data Exchange (ETDEWEB)

    Bates, J.L.; Griffin, C.W.; Weber, W.J.

    1988-06-01

    The HfO/sub 2/-PrO/sub 1.83/-In/sub 2/O/sub 3/ system has been studied at the Pacific Northwest Laboratory to develop alternative, highly electrically conducting oxides as electrode and interconnection materials for solid oxide fuel cells. A coprecipitation process was developed for synthesizing single-phase, mixed oxide powders necessary to fabricate powders and dense oxides. A ternary phase diagram was developed, and the phases and structures were related to electrical transport properties. Two new phases, an orthorhombic PrInO/sub 3/ and a rhombohedral Hf/sub 2/In/sub 2/O/sub 7/ phase, were identified. The highest electronic conductivity is related to the presence of a bcc, In/sub 2/O/sub 3/ solid solution (ss) containing HfO/sub 2/ and PrO/sub 1.83/. Compositions containing more than 35 mol % of the In/sub 2/O/sub 3/ ss have electrical conductivities greater than 10/sup /minus/1/ (ohm-cm)/sup /minus/1/, and the two or three phase structures that contain this phase appear to exhibit mixed electronic-ionic conduction. The high electrical conductivities and structures similar to the Y/sub 2/O/sub 3/-stabilized ZrO/sub 2/(HfO/sub 2/) electrolyte give these oxides potential for use as cathodes in solid oxide fuel cells. 21 refs.

  14. Thin film metal-oxides

    CERN Document Server

    Ramanathan, Shriram

    2009-01-01

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

  15. Amphoteric Aqueous Hafnium Cluster Chemistry.

    Science.gov (United States)

    Goberna-Ferrón, Sara; Park, Deok-Hie; Amador, Jenn M; Keszler, Douglas A; Nyman, May

    2016-05-17

    Selective dissolution of hafnium-peroxo-sulfate films in aqueous tetramethylammonium hydroxide enables extreme UV lithographic patterning of sub-10 nm HfO2 structures. Hafnium speciation under these basic conditions (pH>10), however, is unknown, as studies of hafnium aqueous chemistry have been limited to acid. Here, we report synthesis, crystal growth, and structural characterization of the first polynuclear hydroxo hafnium cluster isolated from base, [TMA]6 [Hf6 (μ-O2 )6 (μ-OH)6 (OH)12 ]⋅38 H2 O. The solution behavior of the cluster, including supramolecular assembly via hydrogen bonding is detailed via small-angle X-ray scattering (SAXS) and electrospray ionization mass spectrometry (ESI-MS). The study opens a new chapter in the aqueous chemistry of hafnium, exemplifying the concept of amphoteric clusters and informing a critical process in single-digit-nm lithography. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Rare Earth Oxide Thin Films

    CERN Document Server

    Fanciulli, Marco

    2007-01-01

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

  17. Oxidation Characterization of Hafnium-Based Ceramics Fabricated by Hot Pressing and Electric Field-Assisted Sintering

    Science.gov (United States)

    Gasch, Matt; Johnson, Sylvia; Marschall, Jochen

    2010-01-01

    Ceramic borides, such as hafnium diboride (HfB2) and zirconium diboride (ZrB2), are members of a family of materials with extremely high melting temperatures referred to as Ultra High Temperature Ceramics (UHTCs). UHTCs constitute a class of promising materials for use in high temperature applications, such as sharp leading edges on future-generation hypersonic flight vehicles, because of their high melting points. The controlled development of microstructure has become important to the processing of UHTCs, with the prospect of improving their mechanical and thermal properties. The improved oxidation resistance of HfB2 has also become important if this material is to be successfully used at temperatures above 2000 C. Furthermore, the use of UHTCs on the leading edges of vehicles traveling at hypersonic speeds will mean exposure to a mixed oxidation environment comprised of both molecular and atomic oxygen. The current study has investigated the high-temperature oxidation behavior of HfB2-based materials in a pure O2 environment, as well as in environments containing different levels of dissociated oxygen (O/O2). Materials were processed by two techniques: conventional hot pressing (HP) and electric field-assisted sintering (FAS). Their oxidation behavior was evaluated in both a tube furnace at 1250 C for 3 hours and in a simulated re-entry environment in the Advanced Heating Facility (AHF) arcjet at NASA Ames Research Center, during a 10-minute exposure to a cold wall heat flux of 250W/sq cm and stagnation pressure of 0.1-0.2 atm. The microstructure of the different materials was characterized before and after oxidation using scanning electron microscopy (SEM).

  18. Immobilization mechanisms of deoxyribonucleic acid (DNA) to hafnium dioxide (HfO2) surfaces for biosensing applications.

    Science.gov (United States)

    Fahrenkopf, Nicholas M; Rice, P Zachary; Bergkvist, Magnus; Deskins, N Aaron; Cady, Nathaniel C

    2012-10-24

    Immobilization of biomolecular probes to the sensing substrate is a critical step for biosensor fabrication. In this work we investigated the phosphate-dependent, oriented immobilization of DNA to hafnium dioxide surfaces for biosensing applications. Phosphate-dependent immobilization was confirmed on a wide range of hafnium oxide surfaces; however, a second interaction mode was observed on monoclinic hafnium dioxide. On the basis of previous materials studies on these films, DNA immobilization studies, and density functional theory (DFT) modeling, we propose that this secondary interaction is between the exposed nucleobases of single stranded DNA and the surface. The lattice spacing of monoclinic hafnium dioxide matches the base-to-base pitch of DNA. Monoclinic hafnium dioxide is advantageous for nanoelectronic applications, yet because of this secondary DNA immobilization mechanism, it could impede DNA hybridization or cause nonspecific surface intereactions. Nonetheless, DNA immobilization on polycrystalline and amorphous hafnium dioxide is predominately mediated by the terminal phosphate in an oriented manner which is desirable for biosensing applications.

  19. Chemical Bonding, Interfaces and Defects in Hafnium Oxide/Germanium Oxynitride Gate Stacks on Ge (100)

    Energy Technology Data Exchange (ETDEWEB)

    Oshima, Yasuhiro; /Stanford U., Materials Sci. Dept.; Sun, Yun; /SLAC, SSRL; Kuzum, Duygu; /Stanford U.; Sugawara, Takuya; Saraswat, Krishna C.; Pianetta, Piero; /SLAC, SSRL; McIntyre, Paul C.; /Stanford U., Materials Sci. Dept.

    2008-10-31

    Correlations among interface properties and chemical bonding characteristics in HfO{sub 2}/GeO{sub x}N{sub y}/Ge MIS stacks were investigated using in-situ remote nitridation of the Ge (100) surface prior to HfO{sub 2} atomic layer deposition (ALD). Ultra thin ({approx}1.1 nm), thermally stable and aqueous etch-resistant GeO{sub x}N{sub y} interfaces layers that exhibited Ge core level photoelectron spectra (PES) similar to stoichiometric Ge{sub 3}N{sub 4} were synthesized. To evaluate GeO{sub x}N{sub y}/Ge interface defects, the density of interface states (D{sub it}) was extracted by the conductance method across the band gap. Forming gas annealed (FGA) samples exhibited substantially lower D{sub it} ({approx} 1 x 10{sup 12} cm{sup -2} eV{sup -1}) than did high vacuum annealed (HVA) and inert gas anneal (IGA) samples ({approx} 1x 10{sup 13} cm{sup -2} eV{sup -1}). Germanium core level photoelectron spectra from similar FGA-treated samples detected out-diffusion of germanium oxide to the HfO{sub 2} film surface and apparent modification of chemical bonding at the GeO{sub x}N{sub y}/Ge interface, which is related to the reduced D{sub it}.

  20. A Simulation Study on the Feasibility of Radio Enhancement Therapy with Calcium Tungstate and Hafnium Oxide Nanoparticles

    CERN Document Server

    Sherck, Nicholas J

    2016-01-01

    Herein is a simulation study on the radio enhancement potential of calcium tungstate (CaWO4) and hafnium oxide (HfO2) nanoparticles (NPs) relative to gold (Au) NPs. The work utilizes the extensively studied Au NP as the "gold standard" to which the novel materials can be compared. All three materials were investigated in-silico with the software Penetration and Energy Loss of Positrons and Electrons (PENELOPE) developed by Francesc Salvat and distributed in the United States by the Radiation Safety Information Computational Center (RSICC) at Oak Ridge National Laboratory. The aims are: (1) Do CaWO4 and HfO2 NPs function like Au?, and (2) if not, how else might they function to enhance radio therapy? Our investigations have found that HfO2 likely functions as Au, but not as effectively. CaWO4 likely does not function as Au, and we propose that CaWO4 may exhibit cancer killing traits through its intrinsic UV luminescence property.

  1. Hafnium nitride films for thermoreflectance transducers at high temperatures: Potential based on heating from laser absorption

    Science.gov (United States)

    Rost, Christina M.; Braun, Jeffrey; Ferri, Kevin; Backman, Lavina; Giri, Ashutosh; Opila, Elizabeth J.; Maria, Jon-Paul; Hopkins, Patrick E.

    2017-10-01

    Time domain thermoreflectance (TDTR) and frequency domain thermoreflectance (FDTR) are common pump-probe techniques that are used to measure the thermal properties of materials. At elevated temperatures, transducers used in these techniques can become limited by melting or other phase transitions. In this work, time domain thermoreflectance is used to determine the viability of HfN thin film transducers grown on SiO2 through measurements of the SiO2 thermal conductivity up to approximately 1000 K. Further, the reliability of HfN as a transducer is determined by measuring the thermal conductivities of MgO, Al2O3, and diamond at room temperature. The thermoreflectance coefficient of HfN was found to be 1.4 × 10-4 K-1 at 800 nm, one of the highest thermoreflectance coefficients measured at this standard TDTR probe wavelength. Additionally, the high absorption of HfN at 400 nm is shown to enable reliable laser heating to elevate the sample temperature during a measurement, relative to other transducers.

  2. Zirconium and hafnium

    Science.gov (United States)

    Jones, James V.; Piatak, Nadine M.; Bedinger, George M.; Schulz, Klaus J.; DeYoung, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    Zirconium and hafnium are corrosion-resistant metals that are widely used in the chemical and nuclear industries. Most zirconium is consumed in the form of the main ore mineral zircon (ZrSiO4, or as zirconium oxide or other zirconium chemicals. Zirconium and hafnium are both refractory lithophile elements that have nearly identical charge, ionic radii, and ionic potentials. As a result, their geochemical behavior is generally similar. Both elements are classified as incompatible because they have physical and crystallochemical properties that exclude them from the crystal lattices of most rock-forming minerals. Zircon and another, less common, ore mineral, baddeleyite (ZrO2), form primarily as accessory minerals in igneous rocks. The presence and abundance of these ore minerals in igneous rocks are largely controlled by the element concentrations in the magma source and by the processes of melt generation and evolution. The world’s largest primary deposits of zirconium and hafnium are associated with alkaline igneous rocks, and, in one locality on the Kola Peninsula of Murmanskaya Oblast, Russia, baddeleyite is recovered as a byproduct of apatite and magnetite mining. Otherwise, there are few primary igneous deposits of zirconium- and hafnium-bearing minerals with economic value at present. The main ore deposits worldwide are heavy-mineral sands produced by the weathering and erosion of preexisting rocks and the concentration of zircon and other economically important heavy minerals, such as ilmenite and rutile (for titanium), chromite (for chromium), and monazite (for rare-earth elements) in sedimentary systems, particularly in coastal environments. In coastal deposits, heavy-mineral enrichment occurs where sediment is repeatedly reworked by wind, waves, currents, and tidal processes. The resulting heavy-mineral-sand deposits, called placers or paleoplacers, preferentially form at relatively low latitudes on passive continental margins and supply 100 percent of

  3. Oxidation of phenyl and hydride ligands of bis(pentamethylcyclopentadienyl)hafnium derivatives by nitrous oxide via selective oxygen atom transfer reactions: insights from quantum chemistry calculations.

    Science.gov (United States)

    Xie, Hujun; Liu, Chengcheng; Yuan, Ying; Zhou, Tao; Fan, Ting; Lei, Qunfang; Fang, Wenjun

    2016-01-21

    The mechanisms for the oxidation of phenyl and hydride ligands of bis(pentamethylcyclopentadienyl)hafnium derivatives (Cp* = η(5)-C5Me5) by nitrous oxide via selective oxygen atom transfer reactions have been systematically studied by means of density functional theory (DFT) calculations. On the basis of the calculations, we investigated the original mechanism proposed by Hillhouse and co-workers for the activation of N2O. The calculations showed that the complex with an initial O-coordination of N2O to the coordinatively unsaturated Hf center is not a local minimum. Then we proposed a new reaction mechanism to investigate how N2O is activated and why N2O selectively oxidize phenyl and hydride ligands of . Frontier molecular orbital theory analysis indicates that N2O is activated by nucleophilic attack by the phenyl or hydride ligand. Present calculations provide new insights into the activation of N2O involving the direct oxygen atom transfer from nitrous oxide to metal-ligand bonds instead of the generally observed oxygen abstraction reaction to generate metal-oxo species.

  4. Silicon nanowires with high-k hafnium oxide dielectrics for sensitive detection of small nucleic acid oligomers.

    Science.gov (United States)

    Dorvel, Brian R; Reddy, Bobby; Go, Jonghyun; Duarte Guevara, Carlos; Salm, Eric; Alam, Muhammad Ashraful; Bashir, Rashid

    2012-07-24

    Nanobiosensors based on silicon nanowire field effect transistors offer advantages of low cost, label-free detection, and potential for massive parallelization. As a result, these sensors have often been suggested as an attractive option for applications in point-of-care (POC) medical diagnostics. Unfortunately, a number of performance issues, such as gate leakage and current instability due to fluid contact, have prevented widespread adoption of the technology for routine use. High-k dielectrics, such as hafnium oxide (HfO(2)), have the known ability to address these challenges by passivating the exposed surfaces against destabilizing concerns of ion transport. With these fundamental stability issues addressed, a promising target for POC diagnostics and SiNWFETs has been small oligonucleotides, more specifically, microRNA (miRNA). MicroRNAs are small RNA oligonucleotides which bind to mRNAs, causing translational repression of proteins, gene silencing, and expressions are typically altered in several forms of cancer. In this paper, we describe a process for fabricating stable HfO(2) dielectric-based silicon nanowires for biosensing applications. Here we demonstrate sensing of single-stranded DNA analogues to their microRNA cousins using miR-10b and miR-21 as templates, both known to be upregulated in breast cancer. We characterize the effect of surface functionalization on device performance using the miR-10b DNA analogue as the target sequence and different molecular weight poly-l-lysine as the functionalization layer. By optimizing the surface functionalization and fabrication protocol, we were able to achieve <100 fM detection levels of the miR-10b DNA analogue, with a theoretical limit of detection of 1 fM. Moreover, the noncomplementary DNA target strand, based on miR-21, showed very little response, indicating a highly sensitive and highly selective biosensing platform.

  5. Creep and Oxidation of Hafnium Diboride Based Ultra High Temperature Ceramics at 1500C

    Science.gov (United States)

    2015-12-01

    their structural integrity and environmental durability must be assured, which requires a thorough understanding and characterization of their creep and oxidation behavior at relevant service temperatures.

  6. Investigation of the synaptic device based on the resistive switching behavior in hafnium oxide

    Directory of Open Access Journals (Sweden)

    Bin Gao

    2015-02-01

    Full Text Available Metal-oxide based electronics synapse is promising for future neuromorphic computation application due to its simple structure and fab-friendly materials. HfOx resistive switching memory has been demonstrated superior performance such as high speed, low voltage, robust reliability, excellent repeatability, and so on. In this work, the HfOx synaptic device was investigated based on its resistive switching phenomenon. HfOx resistive switching device with different electrodes and dopants were fabricated. TiN/Gd:HfOx/Pt stack exhibited the best synaptic performance, including controllable multilevel ability and low training energy consumption. The training schemes for memory and forgetting were developed.

  7. Gas-phase reaction studies of dipositive hafnium and hafnium oxide ions: generation of the peroxide HfO2(2+).

    Science.gov (United States)

    Lourenço, Célia; Michelini, Maria del Carmen; Marçalo, Joaquim; Gibson, John K; Oliveira, Maria Conceição

    2012-12-27

    Fourier transform ion cyclotron resonance mass spectrometry was used to characterize the gas-phase reactivity of Hf dipositive ions, Hf(2+)and HfO(2+), toward several oxidants: thermodynamically facile O-atom donor N(2)O, ineffective donor CO, and intermediate donors O(2), CO(2), NO, and CH(2)O. The Hf(2+) ion exhibited electron transfer with N(2)O, O(2), NO, and CH(2)O, reflecting the high ionization energy of Hf(+). The HfO(2+) ion was produced by O-atom transfer to Hf(2+) from N(2)O, O(2), and CO(2), and the HfO(2)(2+) ion by O-atom transfer to HfO(2+) from N(2)O; these reactions were fairly efficient. Density functional theory revealed the structure of HfO(2)(2+) as a peroxide. The HfO(2)(2+) ion reacted by electron transfer with N(2)O, CO(2), and CO to give HfO(2)(+). Estimates were made for the second ionization energies of Hf (14.5 ± 0.5 eV), HfO (14.3 ± 0.5 eV), and HfO(2) (16.2 ± 0.5 eV), and also for the bond dissociation energies, D[Hf(2+)-O] = 686 ± 69 kJ mol(-1) and D[OHf(2+)-O] = 186 ± 98 kJ mol(-1). The computed bond dissociation energies, 751 and 270 kJ mol(-1), respectively, are within these experimental ranges. Additionally, it was found that HfO(2)(2+) oxidized CO to CO(2) and is thus a catalyst in the oxidation of CO by N(2)O and that Hf(2+) activates methane to produce a carbene, HfCH(2)(2+).

  8. Cryogenic mechanical loss measurements of heat-treated hafnium dioxide

    Science.gov (United States)

    Abernathy, M. R.; Reid, S.; Chalkley, E.; Bassiri, R.; Martin, I. W.; Evans, K.; Fejer, M. M.; Gretarsson, A.; Harry, G. M.; Hough, J.; MacLaren, I.; Markosyan, A.; Murray, P.; Nawrodt, R.; Penn, S.; Route, R.; Rowan, S.; Seidel, P.

    2011-10-01

    Low mechanical loss, high index-of-refraction thin-film coating materials are of particular interest to the gravitational wave detection community, where reduced mirror coating thermal noise in gravitational wave detectors is desirable. Current studies are focused on understanding the loss of amorphous metal oxides such as SiO2, Ta2O5 and HfO2. Here, we report recent measurements of the temperature dependence of the mechanical loss of ion-beam sputtered hafnium dioxide (HfO2) coatings that have undergone heat treatment. The results indicate that, even when partially crystallized, these coatings have lower loss than amorphous Ta2O5 films below ~100 K and that their loss exhibits some features which are heat-treatment dependent in the temperature range of ~100-200 K, with higher heat treatment yielding lower mechanical loss. The potential for using silica doping of hafnia coatings to prevent crystallization is discussed.

  9. SEPARATING HAFNIUM FROM ZIRCONIUM

    Science.gov (United States)

    Lister, B.A.J.; Duncan, J.F.

    1956-08-21

    A dilute aqueous solution of zirconyl chloride which is 1N to 2N in HCl is passed through a column of a cation exchange resin in acid form thereby absorbing both zirconium and associated hafnium impurity in the mesin. The cation exchange material with the absorbate is then eluted with aqueous sulfuric acid of a O.8N to 1.2N strength. The first portion of the eluate contains the zirconium substantially free of hafnium.

  10. Metal oxide targets produced by the polymer-assisted deposition method

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, Mitch A., E-mail: mitch@berkeley.ed [Department of Chemistry, Room 446 Latimer Hall, University of California Berkeley, Berkeley, CA 94720-1460 (United States); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Ali, Mazhar N.; Chang, Noel N.; Parsons-Moss, T. [Department of Chemistry, Room 446 Latimer Hall, University of California Berkeley, Berkeley, CA 94720-1460 (United States); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Ashby, Paul D. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Gates, Jacklyn M. [Department of Chemistry, Room 446 Latimer Hall, University of California Berkeley, Berkeley, CA 94720-1460 (United States); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Stavsetra, Liv [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Gregorich, Kenneth E.; Nitsche, Heino [Department of Chemistry, Room 446 Latimer Hall, University of California Berkeley, Berkeley, CA 94720-1460 (United States); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2010-02-11

    The polymer-assisted deposition (PAD) method was used to create crack-free homogenous metal oxide films for use as targets in nuclear science applications. Metal oxide films of europium, thulium, and hafnium were prepared as models for actinide oxides. Films produced by a single application of PAD were homogenous and uniform and ranged in thickness from 30 to 320 nm. Reapplication of the PAD method (six times) with a 10% by weight hafnium(IV) solution resulted in an equally homogeneous and uniform film with a total thickness of 600 nm.

  11. Impedance Characterization of the Capacitive field-Effect pH-Sensor Based on a thin-Layer Hafnium Oxide Formed by Atomic Layer Deposition

    Directory of Open Access Journals (Sweden)

    Michael LEE

    2014-05-01

    Full Text Available As a sensing element, silicon dioxide (SiO2 has been applied within ion-sensitive field effect transistors (ISFET. However, a requirement of increasing pH-sensitivity and stability has observed an increased number of insulating materials that obtain high-k gate being applied as FETs. The increased high-k gate reduces the required metal oxide layer and, thus, the fabrication of thin hafnium oxide (HfO2 layers by atomic layer deposition (ALD has grown with interest in recent years. This metal oxide presents advantageous characteristics that can be beneficial for the advancements within miniaturization of complementary metal oxide semiconductor (CMOS technology. In this article, we describe a process for fabrication of HfO2 based on ALD by applying water (H2O as the oxygen precursor. As a first, electrochemical impedance spectroscopy (EIS measurements were performed with varying pH (2-10 to demonstrate the sensitivity of HfO2 as a potential pH sensing material. The Nyquist plot demonstrates a high clear shift of the polarization resistance (Rp between pH 6-10 (R2 = 0.9986, Y = 3,054X + 12,100. At acidic conditions (between pH 2-10, the Rp change was small due to the unmodified oxide gate (R2 = 0.9655, Y = 2,104X + 4,250. These preliminary results demonstrate the HfO2 substrate functioned within basic to neutral conditions and establishes a great potential for applying HfO2 as a dielectric material for future pH measuring FET sensors.

  12. A silicon doped hafnium oxide ferroelectric p–n–p–n SOI tunneling field–effect transistor with steep subthreshold slope and high switching state current ratio

    Directory of Open Access Journals (Sweden)

    Saeid Marjani

    2016-09-01

    Full Text Available In this paper, a silicon–on–insulator (SOI p–n–p–n tunneling field–effect transistor (TFET with a silicon doped hafnium oxide (Si:HfO2 ferroelectric gate stack is proposed and investigated via 2D device simulation with a calibrated nonlocal band–to–band tunneling model. Utilization of Si:HfO2 instead of conventional perovskite ferroelectrics such as lead zirconium titanate (PbZrTiO3 and strontium bismuth tantalate (SrBi2Ta2O9 provides compatibility to the CMOS process as well as improved device scalability. By using Si:HfO2 ferroelectric gate stack, the applied gate voltage is effectively amplified that causes increased electric field at the tunneling junction and reduced tunneling barrier width. Compared with the conventional p–n–p–n SOI TFET, the on–state current and switching state current ratio are appreciably increased; and the average subthreshold slope (SS is effectively reduced. The simulation results of Si:HfO2 ferroelectric p–n–p–n SOI TFET show significant improvement in transconductance (∼9.8X enhancement at high overdrive voltage and average subthreshold slope (∼35% enhancement over nine decades of drain current at room temperature, indicating that this device is a promising candidate to strengthen the performance of p–n–p–n and conventional TFET for a switching performance.

  13. Lithium insertion in sputtered vanadium oxide film

    DEFF Research Database (Denmark)

    West, K.; Zachau-Christiansen, B.; Skaarup, S.V.

    1992-01-01

    were oxygen deficient compared to V2O5. Films prepared in pure argon were reduced to V(4) or lower. The vanadium oxide films were tested in solid-state lithium cells. Films sputtered in oxygen showed electrochemical properties similar to crystalline V2O5. The main differences are a decreased capacity...

  14. Nanomechanical study of amorphous and polycrystalline ALD HfO2 thin films

    Science.gov (United States)

    K. Tapily; J.E. Jakes; D. Gu; H. Baumgart; A.A. Elmustafa

    2011-01-01

    Thin films of hafnium oxide (HfO2) were deposited by atomic layer deposition (ALD). The structural properties of the deposited films were characterised by transmission electron microscopy (TEM) and X-ray diffraction (XRD). We investigated the effect of phase transformations induced by thermal treatments on the mechanical properties of ALD HfO

  15. Technical Note: A simulation study on the feasibility of radiotherapy dose enhancement with calcium tungstate and hafnium oxide nano- and microparticles.

    Science.gov (United States)

    Sherck, Nicholas J; Won, You-Yeon

    2017-12-01

    To assess the radiotherapy dose enhancement (RDE) potential of calcium tungstate (CaWO4 ) and hafnium oxide (HfO2 ) nano- and microparticles (NPs). A Monte Carlo simulation study was conducted to gauge their respective RDE potentials relative to that of the broadly studied gold (Au) NP. The study was warranted due to the promising clinical and preclinical studies involving both CaWO4 and HfO2 NPs as RDE agents in the treatment of various types of cancers. The study provides a baseline RDE to which future experimental RDE trends can be compared to. All three materials were investigated in silico with the software Penetration and Energy Loss of Positrons and Electrons (PENELOPE 2014) developed by Francesc Salvat and distributed in the United States by the Radiation Safety Information Computational Center (RSICC) at Oak Ridge National Laboratory. The work utilizes the extensively studied Au NP as the "gold standard" for a baseline. The key metric used in the evaluation of the materials was the local dose enhancement factor (DEFloc ). An additional metric used, termed the relative enhancement ratio (RER), evaluates material performance at the same mass concentrations. The results of the study indicate that Au has the strongest RDE potential using the DEFloc metric. HfO2 and CaWO4 both underperformed relative to Au with lower DEFloc of 2-3 × and 4-100 ×, respectively. The computational investigation predicts the RDE performance ranking to be: Au > HfO2 > CaWO4 . © 2017 American Association of Physicists in Medicine.

  16. Hafnium - an optical hydrogen sensor spanning six orders in pressure

    NARCIS (Netherlands)

    Boelsma, C.; Bannenberg, L.J.; Van Setten, M. J.; Steinke, N.J.; van Well, A.A.; Dam, B.

    2017-01-01

    Hydrogen detection is essential for its implementation as an energy vector. So far, palladium is considered to be the most effective hydrogen sensing material. Here we show that palladium-capped hafnium thin films show a highly reproducible change in optical transmission in response to a hydrogen

  17. Zinc oxide thin film acoustic sensor

    Energy Technology Data Exchange (ETDEWEB)

    Mohammed, Ali Jasim; Salih, Wafaa Mahdi; Hassan, Marwa Abdul Muhsien; Nusseif, Asmaa Deiaa; Kadhum, Haider Abdullah [Department of Physics , College of Science, Al-Mustansiriyah University, Baghdad (Iraq); Mansour, Hazim Louis [Department of Physics , College of Education, Al-Mustansiriyah University, Baghdad (Iraq)

    2013-12-16

    This paper reports the implementation of (750 nm) thickness of Zinc Oxide (ZnO) thin film for the piezoelectric pressure sensors. The film was prepared and deposited employing the spray pyrolysis technique. XRD results show that the growth preferred orientation is the (002) plane. A polycrystalline thin film (close to mono crystallite like) was obtained. Depending on the Scanning Electron Microscopy photogram, the film homogeneity and thickness were shown. The resonance frequency measured (about 19 kHz) and the damping coefficient was calculated and its value was found to be about (2.5538), the thin film be haves as homogeneous for under and over damped. The thin film pressure sensing was approximately exponentially related with frequency, the thin film was observed to has a good response for mechanical stresses also it is a good material for the piezoelectric properties.

  18. Water clustering on nanostructured iron oxide films

    DEFF Research Database (Denmark)

    Merte, Lindsay Richard; Bechstein, Ralf; Peng, G.

    2014-01-01

    , 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 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...

  19. SEPARATION OF HAFNIUM FROM ZIRCONIUM

    Science.gov (United States)

    Overholser, L.B.; Barton, C.J. Sr.; Ramsey, J.W.

    1960-05-31

    The separation of hafnium impurities from zirconium can be accomplished by means of organic solvent extraction. The hafnium-containing zirconium feed material is dissolved in an aqueous chloride solution and the resulting solution is contacted with an organic hexone phase, with at least one of the phases containing thiocyanate. The hafnium is extracted into the organic phase while zirconium remains in the aqueous phase. Further recovery of zirconium is effected by stripping the onganic phase with a hydrochloric acid solution and commingling the resulting strip solution with the aqueous feed solution. Hexone is recovered and recycled by means of scrubbing the onganic phase with a sulfuric acid solution to remove the hafnium, and thiocyanate is recovered and recycled by means of neutralizing the effluent streams to obtain ammonium thiocyanate.

  20. Mineral resource of the month: zirconium and hafnium

    Science.gov (United States)

    Gambogi, Joseph

    2007-01-01

    Zirconium and hafnium are corrosion-resistant metals that are grouped in the same family as titanium on the periodic table. The two elements commonly occur in oxide and silicate minerals and have significant economic importance in everything from ink, ceramics and golf shoes to nuclear fuel rods.

  1. Electrodeposition of Oriented Cerium Oxide Films

    Directory of Open Access Journals (Sweden)

    Adele Qi Wang

    2013-01-01

    Full Text Available Cerium oxide films of preferred orientation are electrodeposited under anodic conditions. A complexing ligand, acetate, was used to stabilize the cerium (III ion in solution for deposition of the thin films. Fourier transform infrared spectroscopy showed that the ligand and metal tended to bind as a weakly bidentate complex. The crystallite size of the films was in the nanometer range as shown by Raman spectroscopy and was calculated from X-ray diffraction data. Crystallite sizes from 6 to 20 nm were obtained under the anodic deposition conditions. Sintering of the (111 oriented films showed an increase in the (111 orientation with temperatures up to 900°C. Also, the crystallite size increased from 20 nm to 120 nm under sintering conditions. Addition of the deposited films to the substrate improved corrosion resistance for the substrate.

  2. Hafnium germanium telluride

    Science.gov (United States)

    Jang, Gyung-Joo; Yun, Hoseop

    2008-01-01

    The title hafnium germanium telluride, HfGeTe4, has been synthesized by the use of a halide flux and structurally characterized by X-ray diffraction. HfGeTe4 is isostructural with stoichiometric ZrGeTe4 and the Hf site in this compound is also fully occupied. The crystal structure of HfGeTe4 adopts a two-dimensional layered structure, each layer being composed of two unique one-dimensional chains of face-sharing Hf-centered bicapped trigonal prisms and corner-sharing Ge-centered tetra­hedra. These layers stack on top of each other to complete the three-dimensional structure with undulating van der Waals gaps. PMID:21202163

  3. Hafnium germanium telluride

    Directory of Open Access Journals (Sweden)

    Hoseop Yun

    2008-05-01

    Full Text Available The title hafnium germanium telluride, HfGeTe4, has been synthesized by the use of a halide flux and structurally characterized by X-ray diffraction. HfGeTe4 is isostructural with stoichiometric ZrGeTe4 and the Hf site in this compound is also fully occupied. The crystal structure of HfGeTe4 adopts a two-dimensional layered structure, each layer being composed of two unique one-dimensional chains of face-sharing Hf-centered bicapped trigonal prisms and corner-sharing Ge-centered tetrahedra. These layers stack on top of each other to complete the three-dimensional structure with undulating van der Waals gaps.

  4. Hafnium transistor design for neural interfacing.

    Science.gov (United States)

    Parent, David W; Basham, Eric J

    2008-01-01

    A design methodology is presented that uses the EKV model and the g(m)/I(D) biasing technique to design hafnium oxide field effect transistors that are suitable for neural recording circuitry. The DC gain of a common source amplifier is correlated to the structural properties of a Field Effect Transistor (FET) and a Metal Insulator Semiconductor (MIS) capacitor. This approach allows a transistor designer to use a design flow that starts with simple and intuitive 1-D equations for gain that can be verified in 1-D MIS capacitor TCAD simulations, before final TCAD process verification of transistor properties. The DC gain of a common source amplifier is optimized by using fast 1-D simulations and using slower, complex 2-D simulations only for verification. The 1-D equations are used to show that the increased dielectric constant of hafnium oxide allows a higher DC gain for a given oxide thickness. An additional benefit is that the MIS capacitor can be employed to test additional performance parameters important to an open gate transistor such as dielectric stability and ionic penetration.

  5. Patterning of Indium Tin Oxide Films

    Science.gov (United States)

    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.

  6. Epitaxial oxide thin films by pulsed laser deposition: Retrospect and ...

    Indian Academy of Sciences (India)

    component oxide films. Highly stoichiometric, nearly single crystal-like materials in the form of films can be made by PLD. Oxides which are synthesized at high oxygen pressure can be made into films at low oxygen partial pressure. Epitaxial thin films ...

  7. Thin-Film Solid Oxide Fuel Cells

    Science.gov (United States)

    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.

  8. Review of Zinc Oxide Thin Films

    Science.gov (United States)

    2014-12-23

    oriented ZnO:Ga  thin   films   deposited  on  glass  by  laser   ablation   at  different  deposition  temperatures.  The  surface  morphology,  crystalline...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...resistivity provided by indium‐doped  tin  oxide (ITO)  ~ 0.7 x 10‐4 Ω‐cm achieved by deposition of  ITO  films  on glass at 300 oC by pulsed  Laser

  9. Magnetic properties of partially oxidized Fe films

    Science.gov (United States)

    Garcia, Miguel Angel; Lopez-Dominguez, Victor; Hernando, Antonio

    Hybrid magnetic nanostructures exhibit appealing properties due to interface and proximity effects. A simple and interesting system of hybrid magnetic nanomaterials are partially oxidized ferromagnetic films. We have fabricated Fe films by thermal evaporation and performed a partial oxidation to magnetite (Fe3O4) by annealing in air at different times and temperatures. The magnetic properties of the films evolve from those of pure metallic iron to pure magnetite, showing intermediate states where the proximity effects control the magnetic behavior. At some stages, the magnetization curves obtained by SQUID and MOKE magnetometry exhibit important differences due to the dissimilar contribution of both phases to the magneto-optical response of the system This work has been supported by the Ministerio Español de Economia y Competitividad (MINECO) MAT2013-48009-C4-1. V.L.D and M.A.G. acknowledges financial support from BBVA foundation.

  10. Transparent Aluminum Oxide Films by Edge Anodization

    Science.gov (United States)

    Stott, Jonathan; Greenwood, Thomas; Winn, David

    In this paper we present our recent work on manufacturing thin (3 - 5 μm) films of porous aluminum(III) oxide [PAO] using a novel edge-anodization technique. With this modified anodization process, we are able to create transparent PAO films on top of insulating substrates such as glass or plastic. By controlling the processing parameters, the index of refraction of PAO films can be engineered to match the substrate, which gives us a durable reflection-free and scratch-resistant coating over conventional optics or LCD displays. Eventually we hope to create ordered porous aluminum oxide cladding around an optical fiber core, which could have a number of interesting optical properties if the pore spacing can be matched to the wavelength of light in the fiber. This work was funded by Fairfield University startup funding.

  11. Ablation Resistant Zirconium and Hafnium Ceramics

    Science.gov (United States)

    Bull, Jeffrey (Inventor); White, Michael J. (Inventor); Kaufman, Larry (Inventor)

    1998-01-01

    High temperature ablation resistant ceramic composites have been made. These ceramics are composites of zirconium diboride and zirconium carbide with silicon carbide, hafnium diboride and hafnium carbide with silicon carbide and ceramic composites which contain mixed diborides and/or carbides of zirconium and hafnium. along with silicon carbide.

  12. Catalysis by Thin Oxide Films and Oxide Nanoparticles

    Science.gov (United States)

    Rupprechter, Günther; Penner, Simon

    Model systems for transition and noble metal oxide catalysts, either as thin films or nanoparticles, were prepared by vacuum-deposition of oxides or oxidation of metals (particles, thin films, single crystals). These systems, including Ga2O3, In2O3, V2O3, V2O5, Nb2O5, Pd5O4 and PdO, are well suited for atomic scale characterization by surface-specific methods and for catalytic tests. Investigations of structure and composition were carried out by HRTEM, AFM, STM, SAED, LEED, EDX, XPS and DFT. In many cases, the surface structure of oxides does not coincide with truncations of the known bulk structures. The adsorption properties of the oxide models, in particular those of defects such as oxygen vacancies or step edges, were examined by vibrational spectroscopy (FTIR and SFG) and thermal desorption spectroscopy (TPD) of probe molecules (CO, H2, propane and propene). Together with XPS, quantification of surface coverage was performed. The catalytic activity and selectivity of the model oxides at (near) ambient gas pressure were investigated by microreactor studies of methanol steam reforming (MSR), (inverse) water gas shift (WGS) and CO oxidation. The structural/compositional flexibility of oxides leads to significant challenges in their characterization but also imparts them with exceptional catalytic properties.

  13. Sputtered tin oxide and titanium oxide thin films as alternative transparent conductive oxides

    Energy Technology Data Exchange (ETDEWEB)

    Boltz, Janika

    2011-12-12

    Alternative transparent conductive oxides to tin doped indium oxide have been investigated. In this work, antimony doped tin oxide and niobium doped titanium oxide have been studied with the aim to prepare transparent and conductive films. Antimony doped tin oxide and niobium doped titanium oxide belong to different groups of oxides; tin oxide is a soft oxide, while titanium oxide is a hard oxide. Both oxides are isolating materials, in case the stoichiometry is SnO{sub 2} and TiO{sub 2}. In order to achieve transparent and conductive films free carriers have to be generated by oxygen vacancies, by metal ions at interstitial positions in the crystal lattice or by cation doping with Sb or Nb, respectively. Antimony doped tin oxide and niobium doped titanium oxide films have been prepared by reactive direct current magnetron sputtering (dc MS) from metallic targets. The process parameters and the doping concentration in the films have been varied. The films have been electrically, optically and structurally analysed in order to analyse the influence of the process parameters and the doping concentration on the film properties. Post-deposition treatments of the films have been performed in order to improve the film properties. For the deposition of transparent and conductive tin oxide, the dominant parameter during the deposition is the oxygen content in the sputtering gas. The Sb incorporation as doping atoms has a minor influence on the electrical, optical and structural properties. Within a narrow oxygen content in the sputtering gas highly transparent and conductive tin oxide films have been prepared. In this study, the lowest resistivity in the as deposited state is 2.9 m{omega} cm for undoped tin oxide without any postdeposition treatment. The minimum resistivity is related to a transition to crystalline films with the stoichiometry of SnO{sub 2}. At higher oxygen content the films turn out to have a higher resistivity due to an oxygen excess. After post

  14. Corrosion and tribocorrosion of hafnium in simulated body fluids.

    Science.gov (United States)

    Rituerto Sin, J; Neville, A; Emami, N

    2014-08-01

    Hafnium is a passive metal with good biocompatibility and osteogenesis, however, little is known about its resistance to wear and corrosion in biological environments. The corrosion and tribocorrosion behavior of hafnium and commercially pure (CP) titanium in simulated body fluids were investigated using electrochemical techniques. Cyclic polarization scans and open circuit potential measurements were performed in 0.9% NaCl solution and 25% bovine calf serum solution to assess the effect of organic species on the corrosion behavior of the metal. A pin-on-plate configuration tribometer and a three electrode electrochemical cell were integrated to investigate the tribocorrosion performance of the studied materials. The results showed that hafnium has good corrosion resistance. The corrosion density currents measured in its passive state were lower than those measured in the case of CP titanium; however, it showed a higher tendency to suffer from localized corrosion, which was more acute when imperfections were present on the surface. The electrochemical breakdown of the oxide layer was retarded in the presence of proteins. Tribocorrosion tests showed that hafnium has the ability to quickly repassivate after the oxide layer was damaged; however, it showed higher volumetric loss than CP titanium in equivalent wear-corrosion conditions. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 102B: 1157-1164, 2014. © 2013 Wiley Periodicals, Inc.

  15. Zirconium and hafnium in meteorites

    Science.gov (United States)

    Ehmann, W. D.; Chyi, L. L.

    1974-01-01

    The abundances of zirconium and hafnium have been determined in nine stony meteorites by a new, precise neutron-activation technique. The Zr/Hf abundance ratios for the chondrites vary in a rather narrow range, consistent with previously published observations from our group. Replicate analyses of new, carefully selected clean interior samples of the Cl chondrite Orgueil yield mean zirconium and hafnium abundances of 5.2 and 0.10 ppm, respectively. These abundances are lower than we reported earlier for two Cl chondrite samples which we now suspect may have suffered contamination. The new Cl zirconium and hafnium abundances are in closer agreement with predictions based on theories of nucleosynthesis than the earlier data.

  16. Porous Nickel Oxide Film Sensor for Formaldehyde

    Science.gov (United States)

    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.

  17. Galvanostatic Ion Detrapping Rejuvenates Oxide Thin Films.

    Science.gov (United States)

    Arvizu, Miguel A; Wen, Rui-Tao; Primetzhofer, Daniel; Klemberg-Sapieha, Jolanta E; Martinu, Ludvik; Niklasson, Gunnar A; Granqvist, Claes G

    2015-12-09

    Ion trapping under charge insertion-extraction is well-known to degrade the electrochemical performance of oxides. Galvanostatic treatment was recently shown capable to rejuvenate the oxide, but the detailed mechanism remained uncertain. Here we report on amorphous electrochromic (EC) WO3 thin films prepared by sputtering and electrochemically cycled in a lithium-containing electrolyte under conditions leading to severe loss of charge exchange capacity and optical modulation span. Time-of-flight elastic recoil detection analysis (ToF-ERDA) documented pronounced Li(+) trapping associated with the degradation of the EC properties and, importantly, that Li(+) detrapping, caused by a weak constant current drawn through the film for some time, could recover the original EC performance. Thus, ToF-ERDA provided direct and unambiguous evidence for Li(+) detrapping.

  18. Hafnium implanted in iron .2.Isolated Hafnium Nitrogen Complexes

    NARCIS (Netherlands)

    de Bakker, J.M.G.J.; Pleiter, F; Smulders, P.J M

    1993-01-01

    We have used the perturbed angular correlation technique to study the interaction of interstitially diffusing nitrogen atoms with substitutional hafnium atoms implanted in iron. It was found that after post-implantation of 250 eV nitrogen ions at 450 K, isolated HfVN(x) complexes with x = 1, 2 are

  19. Water Clustering on Nanostructured Iron Oxide Films

    Energy Technology Data Exchange (ETDEWEB)

    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.

  20. Water clustering on nanostructured iron oxide films

    Science.gov (United States)

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

    2014-06-01

    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.

  1. Hafnium radioisotope recovery from irradiated tantalum

    Science.gov (United States)

    Taylor, Wayne A.; Jamriska, David J.

    2001-01-01

    Hafnium is recovered from irradiated tantalum by: (a) contacting the irradiated tantalum with at least one acid to obtain a solution of dissolved tantalum; (b) combining an aqueous solution of a calcium compound with the solution of dissolved tantalum to obtain a third combined solution; (c) precipitating hafnium, lanthanide, and insoluble calcium complexes from the third combined solution to obtain a first precipitate; (d) contacting the first precipitate of hafnium, lanthanide and calcium complexes with at least one fluoride ion complexing agent to form a fourth solution; (e) selectively adsorbing lanthanides and calcium from the fourth solution by cationic exchange; (f) separating fluoride ion complexing agent product from hafnium in the fourth solution by adding an aqueous solution of ferric chloride to obtain a second precipitate containing the hafnium and iron; (g) dissolving the second precipitate containing the hafnium and iron in acid to obtain an acid solution of hafnium and iron; (h) selectively adsorbing the iron from the acid solution of hafnium and iron by anionic exchange; (i) drying the ion exchanged hafnium solution to obtain hafnium isotopes. Additionally, if needed to remove residue remaining after the product is dried, dissolution in acid followed by cation exchange, then anion exchange, is performed.

  2. Stabilization flyuorytopodibnoyi structure in oxide vacuum condensate

    Directory of Open Access Journals (Sweden)

    О.М. Заславський

    2006-01-01

    Full Text Available  The influence of the oxide-stabilizer content, M'-cation radius and film deposition temperature on the stabilization of the fluorite-like solid solutions in the zirconium and hafnium oxides-based vacuum condensates, obtained by Laser-evaporating method, was investigated. The optimum parameters of the coatication of the isotropic thermostable coverings was determined. This results were explained by using of the high-speed condensation in vacuum theory.

  3. Atomic Layer Deposition of Hafnium(IV) Oxide on Graphene Oxide: Probing Interfacial Chemistry and Nucleation by using X-ray Absorption and Photoelectron Spectroscopies.

    Science.gov (United States)

    Alivio, Theodore E G; De Jesus, Luis R; Dennis, Robert V; Jia, Ye; Jaye, Cherno; Fischer, Daniel A; Singisetti, Uttam; Banerjee, Sarbajit

    2015-07-27

    Interfacing graphene with metal oxides is of considerable technological importance for modulating carrier density through electrostatic gating as well as for the design of earth-abundant electrocatalysts. Herein, we probe the early stages of the atomic layer deposition (ALD) of HfO2 on graphene oxide using a combination of C and O K-edge near-edge X-ray absorption fine structure spectroscopies and X-ray photoelectron spectroscopy. Dosing with water is observed to promote defunctionalization of graphene oxide as a result of the reaction between water and hydroxyl/epoxide species, which yields carbonyl groups that further react with migratory epoxide species to release CO2 . The carboxylates formed by the reaction of carbonyl and epoxide species facilitate binding of Hf precursors to graphene oxide surfaces. The ALD process is accompanied by recovery of the π-conjugated framework of graphene. The delineation of binding modes provides a means to rationally assemble 2D heterostructures. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Evolution of the mechanical and tribological properties of DLC thin films doped with low-concentration hafnium on 316L steel

    Science.gov (United States)

    Qi, Meng; Xiao, Jianrong; Gong, Chenyang; Jiang, Aihua; Chen, Yong

    2018-01-01

    Low concentrations (surface roughness increased monotonically with increasing Hf concentration. Moreover, the hardness and elastic modulus exhibited high values when the doped Hf concentration was 0.42 at%. Similarly, the tribological behaviors and wear life of Hf-DLC thin films had a low friction coefficient and excellent wear resistance at 0.42 at% Hf concentration. Therefore, 0.42 at% Hf is an optimal doping concentration to improve the mechanical and tribological properties of DLC thin films. Generally, the use of low-concentration Hf doping into DLC thin films is novel, and the present results provide guidance for the selection of suitable and effective concentration to optimize Hf-DLC thin films with superior performance.

  5. Hafnium isotope stratigraphy of ferromanganese crusts

    Science.gov (United States)

    Lee, D.-C.; Halliday, A.N.; Hein, J.R.; Burton, K.W.; Christensen, J.N.; Gunther, D.

    1999-01-01

    A Cenozoic record of hafnium isotopic compositions of central Pacific deep water has been obtained from two ferromanganese crusts. The crusts are separated by more than 3000 kilometers but display similar secular variations. Significant fluctuations in hafnium isotopic composition occurred in the Eocene and Oligocene, possibly related to direct advection from the Indian and Atlantic oceans. Hafnium isotopic compositions have remained approximately uniform for the past 20 million years, probably reflecting increased isolation of the central Pacific. The mechanisms responsible for the increase in 87Sr/86Sr in seawater through the Cenozoic apparently had no effect on central Pacific deep-water hafnium.

  6. Hafnium isotope stratigraphy of ferromanganese crusts

    Science.gov (United States)

    Lee; Halliday; Hein; Burton; Christensen; Gunther

    1999-08-13

    A Cenozoic record of hafnium isotopic compositions of central Pacific deep water has been obtained from two ferromanganese crusts. The crusts are separated by more than 3000 kilometers but display similar secular variations. Significant fluctuations in hafnium isotopic composition occurred in the Eocene and Oligocene, possibly related to direct advection from the Indian and Atlantic oceans. Hafnium isotopic compositions have remained approximately uniform for the past 20 million years, probably reflecting increased isolation of the central Pacific. The mechanisms responsible for the increase in (87)Sr/(86)Sr in seawater through the Cenozoic apparently had no effect on central Pacific deep-water hafnium.

  7. Transparent Conductive Oxides in Thin Film Photovoltaics

    Science.gov (United States)

    Hamelmann, Frank U.

    2014-11-01

    This paper show results from the development of transparent conductive oxides (TCO's) on large areas for the use as front electrode in thin film silicon solar modules. It is focused on two types of zinc oxide, which are cheap to produce and scalable to a substrate size up to 6 m2. Low pressure CVD with temperatures below 200°C can be used for the deposition of boron doped ZnO with a native surface texture for good light scattering, while sputtered aluminum doped ZnO needs a post deposition treatment in an acid bath for a rough surface. The paper presents optical and electrical characterization of large area samples, and also results about long term stability of the ZnO samples with respect to the so called TCO corrosion.

  8. Elaboration, structural and spectroscopic properties of rare earth-doped yttrium-hafnium sol-gel oxide powders for scintillation applications

    Energy Technology Data Exchange (ETDEWEB)

    Villanueva-Ibanez, M.; Le Luyer, C.; Dujardin, C.; Mugnier, J

    2003-12-15

    Hafnium dioxide (HfO{sub 2}) presents a high crystalline density ({approx}10 g/cm{sup 3}) which makes it attractive for host lattice activated by rare earths (RE) for applications as scintillating materials. The potentiality to prepare Eu{sup 3+} and Tb{sup 3+} activated HfO{sub 2} sol-gel powders, with high scintillation yield, is explored. The powders are heat-treated at 1000 deg. C before analyses. The incorporation of yttrium (Y{sup 3+}) in various concentrations is conducted to vary the lattice phase and to stabilize the trivalent terbium ions. The influence of Y{sup 3+} on the microstructure and then on the scintillation properties of the material is presented. A high concentration of Y{sup 3+} (20 mol%) stabilizes pure HfO{sub 2} tetragonal phase whatever RE (1 mol%) doping. The powders with the highest relative scintillation yield are Eu{sup 3+}:HfO2 without Y{sup 3+} incorporation and crystallized into the monoclinic phase and Y{sup 3+} (20 mol%): Tb{sup 3+}:HfO2 crystallized into the tetragonal phase. Sequential energy transfer process is assumed to explain these results.

  9. Silver-hafnium braze alloy

    Science.gov (United States)

    Stephens, Jr., John J.; Hosking, F. Michael; Yost, Frederick G.

    2003-12-16

    A binary allow braze composition has been prepared and used in a bonded article of ceramic-ceramic and ceramic-metal materials. The braze composition comprises greater than approximately 95 wt % silver, greater than approximately 2 wt % hafnium and less than approximately 4.1 wt % hafnium, and less than approximately 0.2 wt % trace elements. The binary braze alloy is used to join a ceramic material to another ceramic material or a ceramic material, such as alumina, quartz, aluminum nitride, silicon nitride, silicon carbide, and mullite, to a metal material, such as iron-based metals, cobalt-based metals, nickel-based metals, molybdenum-based metals, tungsten-based metals, niobium-based metals, and tantalum-based metals. A hermetic bonded article is obtained with a strength greater than 10,000 psi.

  10. Thin cuprous oxide films prepared by thermal oxidation of copper foils with water vapor

    Energy Technology Data Exchange (ETDEWEB)

    Liang Jianbo, E-mail: liangjienbo1980@yahoo.co.jp [Department of Frontier Materials,Nagoya Institute of Technology, Nagoya 4668555 (Japan); Kishi, Naoki; Soga, Tetsuo [Department of Frontier Materials,Nagoya Institute of Technology, Nagoya 4668555 (Japan); Jimbo, Takashi [Research Center for Nano-Device and System, Nagoya Institute of Technology, Nagoya 4668555 (Japan); Ahmed, Mohsin [Department of Frontier Materials,Nagoya Institute of Technology, Nagoya 4668555 (Japan)

    2012-01-31

    We present an improved preparation method for the growth of high quality crystals of cuprous oxide films grown by thermal oxidation of cupper foils with water vapor. This method proved to be good for preparing cuprous oxide films with high purity and large grain size. X-ray diffraction studies revealed the formation of Cu{sub 2}O films with preferred (111) orientation. The cuprous oxide diodes fabricated by the above technique have been studied using current-voltage method.

  11. Improved zinc oxide film for gas sensor applications

    Indian Academy of Sciences (India)

    Unknown

    to the other CVD techniques, simultaneously yielding reasonably good quality films for sensor applications. The deposited films were confirmed to be polycrystalline zinc oxide by XRD analysis. The change in electrical resistance of the films was measured while exposing those to the different concentrations of DMA vapour.

  12. Synthesis and characterization of thermally oxidized ZnO films

    Indian Academy of Sciences (India)

    Administrator

    The main goal of this paper is to establish some corre- lations between the oxidation conditions and optical, electrical and gas sensing properties of ZnO thin films. 2. Experimental. The preparation method of ZnO thin films consists of two steps: (a) deposition of zinc metallic films by thermal evaporation under vacuum and (b) ...

  13. Properties of advanced (reduced) graphene oxide-alginate biopolymer films

    NARCIS (Netherlands)

    Vilcinskas, K.

    2016-01-01

    In this work, properties of Calcium alginate-reduced graphene oxide and Barium alginate‐reduced graphene oxide composite films are explored. In addition, the properties of the divalent metal ion-cross-linked alginate composite films are compared to the analogous properties of uncross‐linked Sodium

  14. Synthesis and characterization of zinc oxide thin films prepared by ...

    African Journals Online (AJOL)

    Synthesis and characterization of zinc oxide thin films prepared by chemical the bath technique. ... The band gap energy of the samples deduced from the fundamental absorption edge gave the values of 1.60 – 2.80 eV for the direct ... Keywords: Chemical bath technique, zinc oxide thin films, x-ray, photovoltaic cells ...

  15. Characterization of molybdenum-doped indium oxide thin films by ...

    Indian Academy of Sciences (India)

    index, extension coefficient and bandgap of these films also were investigated. Keywords. Molybdenum-doped indium oxide; spray pyrolysis; thin films. 1. Introduction. Transparent conducting oxide (TCOs) films such as In2O3,. ZnO, SnO2 and In2O3:Sn (ITO), In2O3:Mo (IMO), etc due to their high optical transparency in the ...

  16. Oxidation of Lead Frame Copper Alloys with Different Compositions and Its Effect on Oxide Film Adhesion

    Science.gov (United States)

    Chen, Xi; Hu, Anmin; Li, Ming; Mao, Dali

    2009-02-01

    Oxidation of four typical lead frame copper alloys was investigated. The oxidation rate and adhesion strength of oxide films to copper alloy substrates were studied by measuring the thickness and carrying out peel tests. The results show that, although copper alloys C5191 and C7025 have thinner oxide films, a lower adhesion strength and a higher proportion of CuO were obtained than in the other copper alloys EFTEC64T and C194. The adhesion strength is mainly influenced by the structure of the oxide film of the copper alloys, especially the CuO/Cu2O ratio in the film. The highest adhesion strength is obtained for the copper oxide film with a basic structure of CuO/Cu2O/Cu and a CuO/Cu2O ratio of about 0.1. The segregation of additional elements in the copper alloy plays an important role in the oxide film structure.

  17. Process for separating hafnium and zirconium

    NARCIS (Netherlands)

    Xiao, Y.; Van Sandwijk, A.

    2010-01-01

    The invention is directed to a process for separating a mixture comprising hafnium and zirconium. The process of the present invention comprises a step in which a molten metal phase comprising zirconium and hafnium dissolved in a first metal M1 and a second metal M2 is contacted with a molten salt

  18. Comparison of HfCl{sub 4}, HfI{sub 4}, TEMA-Hf, and TDMA-Hf as precursors in early growing stages of HfO{sub 2} films deposited by ALD: A DFT study

    Energy Technology Data Exchange (ETDEWEB)

    Cortez-Valadez, M. [Departamento de Investigación en Física, Universidad de Sonora, Apdo. Postal 5-88, 83190 Hermosillo, Son. (Mexico); Fierro, C.; Farias-Mancilla, J.R. [Instituto de Ingeniería y Tecnología, Departamento de Física y Matemáticas, Universidad Autónoma de Ciudad Juárez, Av. del Charro 450, Cd. Juárez C.P. 32310, Chihuahua (Mexico); Vargas-Ortiz, A. [Universidad Autónoma de Sinaloa, Facultad de Ingeniería Mochis, Ciudad Universitaria, C.P. 81223 Los Mochis, Sinaloa (Mexico); Flores-Acosta, M. [Departamento de Investigación en Física, Universidad de Sonora, Apdo. Postal 5-88, 83190 Hermosillo, Son. (Mexico); Ramírez-Bon, R. [Centro de Investigación y Estudios Avanzados del IPN, Unidad Querétaro, Apdo. Postal 1-798, 76001 Querétaro, Qro. (Mexico); Enriquez-Carrejo, J.L. [Instituto de Ingeniería y Tecnología, Departamento de Física y Matemáticas, Universidad Autónoma de Ciudad Juárez, Av. del Charro 450, Cd. Juárez C.P. 32310, Chihuahua (Mexico); and others

    2016-06-15

    Highlights: • Hafnium oxide growth on Si(100) by atomic layer deposition was simulated. • The interface structure was considered as silicate and silicide. • The interface was studied employing DFT. • TDMA-Hf precursor show better interface stability. - Abstract: The final structure of HfO{sub 2} films grown by atomic layer deposition (ALD) after reaction with OH{sup −} ions has been analyzed by DFT (density functional theory). The interaction of the precursors: HfCl{sub 4} (hafnium tetrachloride), HfI{sub 4} (hafnium tetraiodide), TEMA-Hf (tetrakis-ethylmethylamino hafnium), and TDMA-Hf (tetrakis-dimethylamino hafnium) with HO–H was studied employing the B3LYP (Becke 3-parameter, Lee–Yang–Parr) hybrid functional and the PBE (Perdew–Burke–Ernzerhof) generalized gradient functional. The structural evolution at the Si(100) surface has been analyzed by LDA (local density approximation). The structural parameters: bond length and bond angle, and the vibrational parameters for the optimized structures are also reported. The presence of hafnium silicate at the interface was detected. The infrared spectra and structural parameters obtained in this work agree with previously reported experimental results.

  19. Cuprous oxide thin films grown by hydrothermal electrochemical deposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Majumder, M., E-mail: mousumi@cgcri.res.in; Biswas, I.; Pujaru, S.; Chakraborty, A.K.

    2015-08-31

    Semiconducting cuprous oxide films were grown by a hydrothermal electro-deposition technique on metal (Cu) and glass (ITO) substrates between 60 °C and 100 °C. X-ray diffraction studies reveal the formation of cubic cuprous oxide films in different preferred orientations depending upon the deposition technique used. Film growth, uniformity, grain size, optical band gap and photoelectrochemical response were found to improve in the hydrothermal electrochemical deposition technique. - Highlights: • Cu{sub 2}O thin films were grown on Cu and glass substrates. • Conventional and hydrothermal electrochemical deposition techniques were used. • Hydrothermal electrochemical growth showed improved morphology, thickness and optical band gap.

  20. Optical characterization of hafnia films deposited by ALD on copper cold-rolled sheets by difference ellipsometry

    Science.gov (United States)

    Franta, Daniel; Kotilainen, Minna; Krumpolec, Richard; Ohlídal, Ivan

    2017-11-01

    Hafnium oxide (HfO2) thin films could be potentially used as thermal diffusion barrier coatings for copper absorbers used in solar thermal collectors. Atomic layer deposition (ALD) was used to deposit thin, dense, non-columnar HfO2 films on copper sheets, which are established base materials for solar absorbers. The aim of this work is to find a simple and efficient method for quantitative characterization of thin hafnium oxide films deposited on imperfect rough copper sheets. The difference ellipsometry applied in infrared region was found to be a practical tool for non-destructive characterization of thin films deposited onto metal surfaces even when these surfaces are imperfect. The presented method enables us not only to identify the presence of hafnium oxide but also to perform quantitative characterization, i.e. to determine the thickness of the film. Moreover, a simple method, in which the thickness is determined from the height of the structure in the difference ellipsometric data, is presented. This method is demonstrated on HfO2 film with nominal thickness 60 nm deposited by ALD on copper cold-rolled sheet.

  1. Electrochromic study on amorphous tungsten oxide films by sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chuan, E-mail: cli10@yahoo.com [Department of Biomedical Engineering, National Yang Ming University, Taipei 11221, Taiwan (China); Department of Mechanical Engineering, National Central University, Jhongli, Taoyuan 32001, Taiwan (China); Hsieh, J.H. [Department of Materials Engineering, Ming Chi University of Technology, Taishan, Taipei 24301, Taiwan (China); Hung, Ming-Tsung [Department of Mechanical Engineering, National Central University, Jhongli, Taoyuan 32001, Taiwan (China); Huang, B.Q. [Department of Biomedical Engineering, National Yang Ming University, Taipei 11221, Taiwan (China)

    2015-07-31

    Tungsten oxide films under different oxygen flow rates are deposited by DC sputtering. The voltage change at target and analyses for the deposited films by X-ray diffraction, scanning electronic microscope, X-ray photoelectron spectroscopy and ultraviolet–visible-near infrared spectroscopy consistently indicate that low oxygen flow rate (5 sccm) only creates metal-rich tungsten oxide films, while higher oxygen flow rate (10–20 sccm) assures the deposition of amorphous WO{sub 3} films. To explore the electrochromic function of deposited WO{sub 3} films, we use electrochemical tests to perform the insertion of lithium ions and electrons into films. The WO{sub 3} films switch between color and bleach states effectively by both potentiostat and cyclic voltammetry. Quantitative evaluation on electrochemical tests indicates that WO{sub 3} film with composition close to its stoichiometry is an optimal choice for electrochromic function. - Highlights: • Amorphous WO{sub 3} films are deposited by DC sputtering under different O{sub 2} flow rates. • Higher oxygen flow rate (> 10 sccm) assures the deposition of amorphous WO{sub 3} films. • Both potentiostat and cyclic voltammetry make WO{sub 3} films switch its color. • An optimal electrochromic WO{sub 3} is to make films close to its stoichiometry.

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

    Science.gov (United States)

    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.

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

    KAUST Repository

    Santiso, José

    2010-10-24

    This paper reviews the recent advances in the use of thin films, mostly epitaxial, for fundamental studies of materials for solid oxide fuel cell (SOFC) applications. These studies include the influence of film microstructure, crystal orientation and strain in oxide ionic conducting materials used as electrolytes, such as fluorites, and in mixed ionic and electronic conducting materials used as electrodes, typically oxides with perovskite or perovskite-related layered structures. The recent effort towards the enhancement of the electrochemical performance of SOFC materials through the deposition of artificial film heterostructures is also presented. These thin films have been engineered at a nanoscale level, such as the case of epitaxial multilayers or nanocomposite cermet materials. The recent progress in the implementation of thin films in SOFC devices is also reported. © 2010 Springer-Verlag.

  4. Chemical solution deposition of functional oxide thin films

    CERN Document Server

    Schneller, Theodor; Kosec, Marija

    2014-01-01

    Chemical Solution Deposition (CSD) is a highly-flexible and inexpensive technique for the fabrication of functional oxide thin films. Featuring nearly 400 illustrations, this text covers all aspects of the technique.

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

    NARCIS (Netherlands)

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

    2015-01-01

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

  6. Chitosan–silver oxide nanocomposite film: Preparation and ...

    Indian Academy of Sciences (India)

    The antibacterial activity of the composite film against pathogenic bacteria viz. Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa was measured by agar diffusion method. Our observations suggest that chitosan as biomaterial based nanocomposite film containing silver oxide has an ...

  7. CO2 gas sensitivity of sputtered zinc oxide thin films

    Indian Academy of Sciences (India)

    TECS

    Abstract. For the first time, sputtered zinc oxide (ZnO) thin films have been used as a CO2 gas sensor. Zinc oxide thin films have been synthesized using reactive d.c. sputtering method for gas sensor applications, in the deposition temperature range from 130–153°C at a chamber pressure of 8⋅5 mbar for 18 h. Argon and ...

  8. Thin film zinc oxide deposited by CVD and PVD

    Science.gov (United States)

    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.

  9. Understanding Organic Film Behavior on Alloy and Metal Oxides

    Science.gov (United States)

    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

  10. Thermal Expansion of Hafnium Carbide

    Science.gov (United States)

    Grisaffe, Salvatore J.

    1960-01-01

    Since hafnium carbide (HfC) has a melting point of 7029 deg. F, it may have many high-temperature applications. A literature search uncovered very little information about the properties of HfC, and so a program was initiated at the Lewis Research Center to determine some of the physical properties of this material. This note presents the results of the thermal expansion investigation. The thermal-expansion measurements were made with a Gaertner dilatation interferometer calibrated to an accuracy of +/- 1 deg. F. This device indicates expansion by the movement of fringes produced by the cancellation and reinforcement of fixed wave-length light rays which are reflected from the surfaces of two parallel quartz glass disks. The test specimens which separate these disks are three small cones, each approximately 0.20 in. high.

  11. Spatial atomic layer deposition of zinc oxide thin films

    NARCIS (Netherlands)

    Illiberi, A.; Roozeboom, F.; Poodt, P.W.G.

    2012-01-01

    Zinc oxide thin films have been deposited at high growth rates (up to ~1 nm/s) by spatial atomic layer deposition technique at atmospheric pressure. Water has been used as oxidant for diethylzinc (DEZ) at deposition temperatures between 75 and 250 °C. The electrical, structural (crystallinity and

  12. Structural, electronic and chemical properties of metal/oxide and oxide/oxide interfaces and thin film structures

    Energy Technology Data Exchange (ETDEWEB)

    Lad, Robert J.

    1999-12-14

    This project focused on three different aspects of oxide thin film systems: (1) Model metal/oxide and oxide/oxide interface studies were carried out by depositing ultra-thin metal (Al, K, Mg) and oxide (MgO, AlO{sub x}) films on TiO{sub 2}, NiO and {alpha}-Al{sub 2}O{sub 3} single crystal oxide substrates. (2) Electron cyclotron resonance (ECR) oxygen plasma deposition was used to fabricate AlO{sub 3} and ZrO{sub 2} films on sapphire substrates, and film growth mechanisms and structural characteristics were investigated. (3) The friction and wear characteristics of ZrO{sub 2} films on sapphire substrates in unlubricated sliding contact were studied and correlated with film microstructure. In these studies, thin film and interfacial regions were characterized using diffraction (RHEED, LEED, XRD), electron spectroscopies (XPS, UPS, AES), microscopy (AFM) and tribology instruments (pin-on-disk, friction microprobe, and scratch tester). By precise control of thin film microstructure, an increased understanding of the structural and chemical stability of interface regions and tribological performance of ultra-thin oxide films was achieved in these important ceramic systems.

  13. Sn-doped Zinc Oxide thin films for LPG sensors

    Directory of Open Access Journals (Sweden)

    R. K. Nath

    2012-03-01

    Full Text Available Sn doped zinc oxide (ZnO:Sn thin films have been prepared by chemical spray pyrolysis technique using Zn(CH3COO2 as a precursor solution and SnCl4 as a doping solution respectively. The dopant concentration (Sn/Zn at% is varied from 0 to 1.5 at%. The structural, morphological, optical and electrical properties of the films are explored and then tested for LPG sensing. The resistivity of the Sn-doped films decreases with the Sn doping up to 0.5at%, while at a higher doping concentration the disorder produced in the lattice causes an increase in resistivity of the films. Exposure of LPG decreases the resistance of undoped and doped films. The response of the film is measured for both ZnO and ZnO:Sn films at different operating temperature (275-400℃ and concentration (vol % of LPG in air. It is observed that Sn-doped ZnO films are more sensitive to LPG than undoped ZnO film. In this work, maximum response (~88 % is observed for 0.5at % ZnO:Sn film for 1 vol% of LPG in air at 300℃. Further all the films have shown faster response and recovery times at higher operating temperatures

  14. Sn-doped Zinc Oxide Thin Films for Methanol

    Directory of Open Access Journals (Sweden)

    Rajarshi Krishna NATH

    2009-09-01

    Full Text Available Sn doped zinc oxide (ZnO:Sn thin films have been prepared by chemical spray pyrolysis technique with dopant concentration (Sn/Zn at % from 0 to 1.5 at %. The structural, morphological, optical and electrical properties of the films are explored and then tested for methanol sensing. The resistivity of the films decreases with Sn doping up to 0.5 at %, while at higher doping concentration the disorder produced in the lattice causes an increase in resistivity of the films. Exposure of methanol decreases the resistance of the films. The response of the film is measured for both ZnO and ZnO:Sn films at different operating temperature (200-350 0C and concentration (ppm of methanol in air. It is observed that ZnO:Sn films are more sensitive to methanol than undoped ZnO film. The maximum response (~53 % is observed for 0.5at % ZnO:Sn film to 500 ppm of methanol in air at 300 0C. Further the films have shown faster response and recovery times at higher operating temperatures.

  15. Characterizations of photoconductivity of graphene oxide thin films

    Directory of Open Access Journals (Sweden)

    Shiang-Kuo Chang-Jian

    2012-06-01

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

  16. Metal Doped Manganese Oxide Thin Films for Supercapacitor Application.

    Science.gov (United States)

    Tung, Mai Thanh; Thuy, Hoang Thi Bich; Hang, Le Thi Thu

    2015-09-01

    Co and Fe doped manganese oxide thin films were prepared by anodic deposition at current density of 50 mA cm(-2) using the electrolyte containing manganese sulfate and either cobalt sulfate or ferrous sulfate. Surface morphology and crystal structure of oxides were studied by scanning electron microscope (SEM) and X-ray diffraction (XRD). Chemical composition of materials was analyzed by X-ray energy dispersive spectroscope (EDS), iodometric titration method and complexometric titration method, respectively. Supercapacitive behavior of Co and Fe doped manganese oxide films were characterized by cyclic voltammetry (CV) and impedance spectroscopy (EIS). The results show that the doped manganese oxides are composed of nano fiber-like structure with radius of 5-20 nm and remain amorphous structure after heat treatment at 100 degrees C for 2 hours. The average valence of manganese increases from +3.808 to +3.867 after doping Co and from +3.808 to +3.846 after doping Fe. The doped manganese oxide film electrodes exhibited preferably ideal pseudo-capacitive behavior. The specific capacitance value of deposited manganese oxide reaches a maximum of 175.3 F/g for doping Co and 244.6 F/g for doping Fe. The thin films retained about 84% of the initial capacity even after 500 cycles of charge-discharge test. Doping Co and Fe decreases diffusion and charge transfer resistance of the films. The electric double layer capacitance and capacitor response frequency are increased after doping.

  17. Oxide-based thin film transistors for flexible electronics

    Science.gov (United States)

    He, Yongli; Wang, Xiangyu; Gao, Ya; Hou, Yahui; Wan, Qing

    2018-01-01

    The continuous progress in thin film materials and devices has greatly promoted the development in the field of flexible electronics. As one of the most common thin film devices, thin film transistors (TFTs) are significant building blocks for flexible platforms. Flexible oxide-based TFTs are well compatible with flexible electronic systems due to low process temperature, high carrier mobility, and good uniformity. The present article is a review of the recent progress and major trends in the field of flexible oxide-based thin film transistors. First, an introduction of flexible electronics and flexible oxide-based thin film transistors is given. Next, we introduce oxide semiconductor materials and various flexible oxide-based TFTs classified by substrate materials including polymer plastics, paper sheets, metal foils, and flexible thin glass. Afterwards, applications of flexible oxide-based TFTs including bendable sensors, memories, circuits, and displays are presented. Finally, we give conclusions and a prospect for possible development trends. Project supported in part by the National Science Foundation for Distinguished Young Scholars of China (No. 61425020), in part by the National Natural Science Foundation of China (No. 11674162).

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

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ching-Ting, E-mail: ctlee@ee.ncku.edu.tw; Lin, Yung-Hao; Lin, Jhong-Ham [Institute of Microelectronics, Department of Electrical Engineering, Research Center for Energy Technology and Strategy (RCETS), National Cheng Kung University, Tainan, Taiwan (China)

    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.

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

    Science.gov (United States)

    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.

  20. Pulsed photonic fabrication of nanostructured metal oxide thin films

    Science.gov (United States)

    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.

  1. WO3 Nanoplates Film: Formation and Photocatalytic Oxidation Studies

    Directory of Open Access Journals (Sweden)

    Chin Wei Lai

    2015-01-01

    Full Text Available High surface area of tungsten oxide (WO3 nanoplates films was prepared via simple electrochemical anodization technique by controlling the fluoride content (NH4F in electrolyte. The design and development of WO3-based nanostructure assemblies have gained significant interest in order to maximize specific surface area for harvesting more photons to trigger photocatalytic oxidation reaction. This study aims to determine the optimum content of NH4F in forming WO3 nanoplates on W film with efficient photocatalytic oxidation reaction for organic dye degradation by utilizing our solar energy. The NH4F was found to influence the chemical dissolution and field-assisted dissolution rates, thus modifying the final morphological of WO3-based nanostructure assemblies film. It was found that 0.7 wt% of NH4F is the minimum amount to grow WO3 nanoplates film on W film. The photocatalysis oxidation experimental results showed that WO3 nanoplates film exhibited a maximum degradation of methyl orange dye (≈75% under solar illumination for 5 hours. This behavior was attributed to the better charge carriers transportation and minimizes the recombination losses with specific surface area of nanoplates structure.

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

    Science.gov (United States)

    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.

  3. Spectroscopic and electrochemical studies of electrochromic hydrated nickel oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Yu, P.C.; Nazri, G.; Lampert, C.M.

    1986-07-01

    The electrochromic properties of hydrated nickel oxide thin films electrochemically deposited by anodization onto doped tin oxide-coated glass have been studied by transmittance measurements, cyclic voltammetry, Fourier-transform infrared spectroscopy, and ion-backscattering spectrometry. The spectral transmittance is reported for films switched in both the bleached and colored states. The photopic transmittance (T/sub p/) can be switched from T/sub p/(bleached) = 0.77 to T/sub p/(colored) = 0.21, and the solar transmittance (T/sub S/) can be switched from T/sub S/(bleached) = 0.73 to T/sub S/(colored = 0.35. Also reported is the near-infrared transmittance (T/sub NIR/), which was found to switch from T/sub NIR/(bleached) = 0.72 to T/sub NIR/(colored) = 0.55 for a film thickness of 500 A. The bleached condition is noted to have very low solar absorption in both the visible and solar regions. Ion-backscattering spectrometry was performed on the hydrated nickel oxide film, yielding a composition of NiO/sub 1.0/ (dehydrated). Cyclic voltammetry showed that, for films in the bleached or colored state, the reversible reaction is Ni(OH)/sub 2/ ..-->.. NiOOH + H/sup +/ + e/sup -/. Voltammetry also showed that the switching of the film is controlled by the diffusion of protons, where OH/sup -/ plays a role in the reaction mechanism. Analysis of the hydrated nickel-oxide thin films by Fourier-transform infrared spectroscopy revealed that both the bleached and colored states contain lattice water and hydroxyl groups. The surface hydroxyl groups play an important role in the coloration and bleaching of the anodically deposited nickel oxide thin films.

  4. Graphene oxide-based transparent conductive films

    National Research Council Canada - National Science Library

    Zheng, Qingbin; Li, Zhigang; Yang, Junhe; Kim, Jang-Kyo

    2014-01-01

    .... Because of its excellent electrical conductivity, optical transparency and mechanical properties, graphene has been considered an ideal material to replace the existing, expensive indium tin oxide (ITO) as TCFs. Graphene oxide (GO...

  5. Electrodeposition of Manganese-Nickel Oxide Films on a Graphite Sheet for Electrochemical Capacitor Applications

    OpenAIRE

    Hae-Min Lee; Kangtaek Lee; Chang-Koo Kim

    2014-01-01

    Manganese-nickel (Mn-Ni) oxide films were electrodeposited on a graphite sheet in a bath consisting of manganese acetate and nickel chloride, and the structural, morphological, and electrochemical properties of these films were investigated. The electrodeposited Mn-Ni oxide films had porous structures covered with nanofibers. The X-ray diffractometer pattern revealed the presence of separate manganese oxide (g-MnO2) and nickel oxide (NiO) in the films. The electrodeposited Mn-Ni oxide electr...

  6. Total Ionizing Dose Response of Hafnium-Oxide Based MOS Devices to Low-Dose-Rate Gamma Ray Radiation Observed by Pulse CV and On-Site Measurements

    Science.gov (United States)

    Mu, Yifei; Zhao, Ce Zhou; Lu, Qifeng; Zhao, Chun; Qi, Yanfei; Lam, Sang; Mitrovic, Ivona Z.; Taylor, Stephen; Chalker, Paul R.

    2017-01-01

    This paper reports on the low-dose-rate radiation response of Al-HfO2/SiO2-Si MOS devices, where the gate dielectric was formed by atomic layer deposition with 4.7 nm equivalent oxide thickness. The degradation of the devices was characterized by a pulse capacitance-voltage (CV) and on-site radiation response techniques under continuous gamma (γ) ray exposure at a relatively low-dose-rate of 0.116 rad(HfO2)/s. A significant variation of the flat-band voltage shift of up to ± 1.1 V under positive and negative biased irradiation, with the total dose of up to 40 krad (HfO2) and the electric field of 0.5 MV/cm, has been measured on the HfO2-based MOS devices using the proposed techniques, not apparent by conventional CV measurements. The large flat-band voltage shift is mainly attributed to the radiation-induced oxide trapped charges, which are not readily compensated by bias-induced charges produced over the measurement timescales of less than 5 ms. Analysis of the experimental results suggest that both hole and electron trapping can dominate the radiation response performance of the HfO2-based MOS devices depending on the applied bias. No distinct loop width variation has been found with irradiation in all cases.

  7. Properties of Spray Pyrolysied Copper Oxide Thin Films

    Directory of Open Access Journals (Sweden)

    S. S. Roy

    2017-02-01

    Full Text Available Copper oxide (CuO thin films were deposited on well cleaned glass substrates by spray pyrolysis technique (SPT from cupric acetate (Cu(CH3COO2.H2O precursor solutions of 0.05 – 0.15 M molar concentrations (MC at a substrate temperature of 350 °C and at an air pressure of 1 bar. Effect of varying MC on the surface morphology, structural optical and electrical properties of CuO thin films were investigated. XRD patterns of the prepared films revealed the formation of CuO thin films having monoclinic structure with the main CuO (111 orientation and crystalline size ranging from 8.02 to 9.05 nm was observed. The optical transmission of the film was found to decrease with the increase of MC. The optical band gap of the thin films for 0.10 M was fond to be 1.60 eV. The room temperature electrical resistivity varies from 31 and 24 ohm.cm for the films grown with MC of 0.05 and 0.10 M respectively. The change in resistivity of the films was studied with respect to the change in temperature was shown that semiconductor nature is present. This information is expected to underlie the successful development of CuO films for solar windows and other semi-conductor applications including gas sensors.

  8. Graphene Oxide Reinforced Polycarbonate Nanocomposite Films with Antibacterial Properties

    Directory of Open Access Journals (Sweden)

    R. Mahendran

    2016-01-01

    Full Text Available The incorporation of carbonaceous nanofillers into polymers can result in significant materials with improved physicochemical properties and novel composite functionalities. In this study, we have fabricated antibacterial, lightweight, transparent, and flexible graphene oxide (GO reinforced polycarbonate thin films by a facile and low-cost methodology. Solution blending is employed to get a homogeneous mixture of PC-GO composites at various loading of GO, and the thin films are prepared by dry-wet phase inversion technique. Thermal studies and micrographs of the films revealed the incorporation of GO in PC matrix. Microstructure of the thin films showed the homogeneous dispersion of GO at micro- and nanoscales; however, at higher loading of GO (0.7%, significant agglomeration is observed. More importantly, PC-GO composite films exhibited excellent antibacterial activities against E. coli and S. aureus, owing to the antibacterial nature of GO nanoparticles.

  9. Optoelectrical and structural properties of evaporated indium oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Naseem, S. (Centre for Solid State Physics, Univ. of the Punjab, Lahore (Pakistan)); Iqbal, M. (Centre for Solid State Physics, Univ. of the Punjab, Lahore (Pakistan)); Hussain, K. (Centre for Solid State Physics, Univ. of the Punjab, Lahore (Pakistan))

    1993-11-01

    Indium oxide thin films have been prepared by evaporating indium metal in the presence of oxygen atmosphere. The oxygen partial pressure was kept at a fixed value, of 1 mTorr, previously found to be optimum for the present investigations. The substrate temperature was varied from room temperature to 300 C. Once an optimum substrate temperature of 250 C was established, more films were prepared at this temperature and these films were then given a post-deposition heat treatment in nitrogen and oxygen atmospheres. The resultant films were characterized for their optical, electrical and structural properties. The results show that films with a resistivity as low as 3.38x10[sup -4] [Omega] cm, and with a transmittance as high as 91% can be achieved by controlling the preparation conditions. (orig.)

  10. Study of zinc oxide thin film characteristics

    Science.gov (United States)

    Johari, Shazlina; Yazmin Muhammad, Nazalea; Rosydi Zakaria, Mohd

    2017-11-01

    This paper presents the characterization of ZnO thin films with the thickness of 8nm, 30nm, and 200nm. The thin films were prepared using sol-gel method and has been deposited onto different substrate of silicon wafer, glass and quartz. The thin films were annealed at 400, 500 and 600°C. By using UV-Vis, the optical transmittance measurement were recorded by using a single beam spectrophotometer in the wavelength 250nm to 800nm. However, the transmittance in the visible range is hardly influenced by the film thickness, substrate used and annealed temperature and the averages are all above 80%. On surface morphology observed by AFM and FESEM, the results show that the increase of film thickness and annealed temperature will increase the mean grain size, surface-to-volume ration and RMS roughness. Besides that, higher annealing temperature cause the crystalline quality to gradually improve and the wurtzite structure of ZnO can be seen more clearly. Nonetheless, the substrate used had no effect on surface morphology, yet the uniformity of deposition on silicon wafer is better than glass and quartz.

  11. The growth of thin film epitaxial oxide-metal heterostructures

    CERN Document Server

    Wang, C

    1998-01-01

    films with lowest IR emissivity are those made from the purest targets despite their having comparable roughnesses to films from lower purity targets. The lowest emissivity achieved was in the range of 1.64% to 1.72% measured at 3.8 mu m for 1.5 to 1.8 mu m thick films. Modifications to standard idealized Drude theory have been made which, in a phenomenological way, take account of imperfections in the sputtered Al film, oxidation state and roughness. in electric properties of the Nb film and the reduction in crystalline quality of the MgO layer. The reduction of transition temperature to the superconducting state, Tc, and the similarly systematic increase in the Nb lattice parameter were observed consistent with oxygen content data reported in the literature, as the Nb became heavily oxidized. Examination of the surface of clean and oxidized Nb by atomic force microscopy, and deposition of MgO in UHV onto a previously oxidized Nb surface, suggested that the decrease in crystalline quality of the MgO can be a...

  12. Comparison of topotactic fluorination methods for complex oxide films

    Directory of Open Access Journals (Sweden)

    E. J. Moon

    2015-06-01

    Full Text Available We have investigated the synthesis of SrFeO3−αFγ (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 SrFeO2.5 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.

  13. All-alkoxide synthesis of strontium-containing metal oxides

    Science.gov (United States)

    Boyle, Timothy J.

    2001-01-01

    A method for making strontium-containing metal-oxide ceramic thin films from a precursor liquid by mixing a strontium neo-pentoxide dissolved in an amine solvent and at least one metal alkoxide dissolved in a solvent, said at least one metal alkoxide selected from the group consisting of alkoxides of calcium, barium, bismuth, cadmium, lead, titanium, tantalum, hafnium, tungsten, niobium, zirconium, yttrium, lanthanum, antimony, chromium and thallium, depositing a thin film of the precursor liquid on a substrate, and heating the thin film in the presence of oxygen at between 550 and 700.degree. C.

  14. Superlubricating graphene and graphene oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Sumant, Anirudha V.; Erdemir, Ali; Choi, Junho; Berman, Diana

    2018-02-13

    A system and method for forming at least one of graphene and graphene oxide on a substrate and an opposed wear member. The system includes graphene and graphene oxide formed by an exfoliation process or solution processing method to dispose graphene and/or graphene oxide onto a substrate. The system further includes an opposing wear member disposed on another substrate and a gas atmosphere of an inert gas like N2, ambient, a humid atmosphere and a water solution.

  15. Multifunctional multilayer films containing polyoxometalates and bismuth oxide nanoparticles.

    Science.gov (United States)

    Li, Chunxiang; O'Halloran, Kevin P; Ma, Huiyuan; Shi, Shilin

    2009-06-11

    Multifunctional multilayer films consisting of the Keggin-type polyoxometalate [SiW(9)V(3)O(40)](7-) (SiW(9)V(3)) and bismuth oxide nanoparticles (Bi(2)O(3)) were prepared by the layer-by-layer assembly method. For the first time, electrochromic and photochromic studies were done on a film containing both polyoxometalates and nanoparticles. The films were characterized by UV-vis absorption, emission spectra, and atomic force microscopy. Their electrochromic and photochromic properties were investigated by cyclic voltammetry and UV-vis spectroscopy. The results show that the reduction of SiW(9)V(3) is very reversible and tunable with the addition of Bi(2)O(3) layers into the film. The electrocatalytic activity of the films toward oxidation of l-cysteine hydrochloride hydrate (l-cysteine) and reduction of nitrite were studied with cyclic voltammetry. The results show that the incorporation of Bi(2)O(3) nanoparticles into the films changed the films' photoluminescence properties and electrocatalytic efficiency.

  16. Investigation of Melting Dynamics of Hafnium Clusters.

    Science.gov (United States)

    Ng, Wei Chun; Lim, Thong Leng; Yoon, Tiem Leong

    2017-03-27

    Melting dynamics of hafnium clusters are investigated using a novel approach based on the idea of the chemical similarity index. Ground state configurations of small hafnium clusters are first derived using Basin-Hopping and Genetic Algorithm in the parallel tempering mode, employing the COMB potential in the energy calculator. These assumed ground state structures are verified by using the Low Lying Structures (LLS) method. The melting process is carried out either by using the direct heating method or prolonged simulated annealing. The melting point is identified by a caloric curve. However, it is found that the global similarity index is much more superior in locating premelting and total melting points of hafnium clusters.

  17. Bismuth iron oxide thin films using atomic layer deposition of alternating bismuth oxide and iron oxide layers

    Energy Technology Data Exchange (ETDEWEB)

    Puttaswamy, Manjunath; Vehkamäki, Marko [University of Helsinki, Department of Chemistry, P.O. Box 55, FI-00014 Helsinki (Finland); Kukli, Kaupo, E-mail: kaupo.kukli@helsinki.fi [University of Helsinki, Department of Chemistry, P.O. Box 55, FI-00014 Helsinki (Finland); University of Tartu, Institute of Physics, W. Ostwald 1, EE-50411 Tartu (Estonia); Dimri, Mukesh Chandra [National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, EE-12618 Tallinn (Estonia); Kemell, Marianna; Hatanpää, Timo; Heikkilä, Mikko J. [University of Helsinki, Department of Chemistry, P.O. Box 55, FI-00014 Helsinki (Finland); Mizohata, Kenichiro [University of Helsinki, Department of Physics, P.O. Box 64, FI-00014 Helsinki (Finland); Stern, Raivo [National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, EE-12618 Tallinn (Estonia); Ritala, Mikko; Leskelä, Markku [University of Helsinki, Department of Chemistry, P.O. Box 55, FI-00014 Helsinki (Finland)

    2016-07-29

    Bismuth iron oxide films with varying contributions from Fe{sub 2}O{sub 3} or Bi{sub 2}O{sub 3} were prepared using atomic layer deposition. Bismuth (III) 2,3-dimethyl-2-butoxide, was used as the bismuth source, iron(III) tert-butoxide as the iron source and water vapor as the oxygen source. The films were deposited as stacks of alternate Bi{sub 2}O{sub 3} and Fe{sub 2}O{sub 3} layers. Films grown at 140 °C to the thickness of 200–220 nm were amorphous, but crystallized upon post-deposition annealing at 500 °C in nitrogen. Annealing of films with intermittent bismuth and iron oxide layers grown to different thicknesses influenced their surface morphology, crystal structure, composition, electrical and magnetic properties. Implications of multiferroic performance were recognized in the films with the remanent charge polarization varying from 1 to 5 μC/cm{sup 2} and magnetic coercivity varying from a few up to 8000 A/m. - Highlights: • Bismuth iron oxide thin films were grown by atomic layer deposition at 140 °C. • The major phase formed in the films upon annealing at 500 °C was BiFeO{sub 3}. • BiFeO{sub 3} films and films containing excess Bi favored electrical charge polarization. • Slight excess of iron oxide enhanced saturative magnetization behavior.

  18. Hafnium nitride buffer layers for growth of GaN on silicon

    Science.gov (United States)

    Armitage, Robert D.; Weber, Eicke R.

    2005-08-16

    Gallium nitride is grown by plasma-assisted molecular-beam epitaxy on (111) and (001) silicon substrates using hafnium nitride buffer layers. Wurtzite GaN epitaxial layers are obtained on both the (111) and (001) HfN/Si surfaces, with crack-free thickness up to 1.2 {character pullout}m. However, growth on the (001) surface results in nearly stress-free films, suggesting that much thicker crack-free layers could be obtained.

  19. Use of hafnium in control bars of nuclear reactors; Uso de hafnio en barras de control de reactores nucleares

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez S, J.R.; Alonso V, G. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)]. e-mail: jrrs@nuclear.inin-mx

    2003-07-01

    Recently the use of hafnium as neutron absorber material in nuclear reactors has been reason of investigation by virtue of that this material has nuclear properties as to the neutrons absorption and structural that can prolong the useful life of the control mechanisms of the nuclear reactors. In this work some of those more significant hafnium properties are presented like nuclear material. Also there are presented calculations carried out with the HELIOS code for fuel cells of uranium oxide and of uranium and plutonium mixed oxides under controlled conditions with conventional bars of boron carbide and also with similar bars to which are substituted the absorbent material by metallic hafnium, the results are presented in this work. (Author)

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

    Science.gov (United States)

    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.

  1. Electrodeposition of nanoporous nickel oxide film for electrochemical capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Mao-Sung; Huang, Yu-An; Yang, Chung-Hsien; Jow, Jiin-Jiang [Department of Chemical and Material Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung 807 (China)

    2007-12-15

    Nanoporous nickel oxide film is electrochemically anodic deposited onto a stainless steel substrate by a plating bath of sodium acetate, nickel sulfate, and sodium sulfate mixture at room temperature without any template or catalyst. The deposited film is highly porous and composed of interconnected nanoflakes of thickness 12-16 nm after 300 {sup circle} C annealing. Specific capacitance of the deposited film depends on the applied potential window significantly in 1 M KOH solution. Specific capacitance is much increased by increasing the upper limit potential due to the contribution of redox reaction of nickel oxide to the measured capacitance. The deposited film shows a superior performance in high-rate charge/discharge capability. Specific capacitance of the deposited electrode is 167.3Fg{sup -1} at 1Ag{sup -1} charge/discharge, and 156.6Fg{sup -1} at 16.5Ag{sup -1}. The film also shows a stable capacitance during cycling. After 5000 test cycles at current density of 4Ag{sup -1}, specific capacitance of the film is 140Fg{sup -1}, approximately 87.5% of its maximum capacitance (160Fg{sup -1}). (author)

  2. Multiferroic oxide thin films and heterostructures

    Science.gov (United States)

    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.

  3. Multiferroic oxide thin films and heterostructures

    KAUST Repository

    Lu, Chengliang

    2015-05-26

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

  4. Characterization of molybdenum-doped indium oxide thin films by ...

    Indian Academy of Sciences (India)

    In this research, indium oxide nanostructure undoped and doped with Mo were prepared on glass substrates using spray pyrolysis technique. Various parameters such as dopant concentration and deposition temperatures were studied. Structural properties of these films were investigated by X-ray diffraction and scanning ...

  5. Optical characteristics of transparent samarium oxide thin films ...

    Indian Academy of Sciences (India)

    Optical characteristics of transparent samarium oxide thin films deposited by the radio-frequency sputtering technique. A A ATTA M M EL-NAHASS KHALED M ELSABAWY M M ABD EL-RAHEEM A M HASSANIEN A ALHUTHALI ALI BADAWI AMAR MERAZGA. Regular Volume 87 Issue 5 November 2016 Article ID 72 ...

  6. Optical characterisation of thin film cadmium oxide prepared by a ...

    African Journals Online (AJOL)

    The optical transmission spectra of transparent conducting cadmium oxide (CdO) thin films deposited by a modified reactive evaporation process onto glass substrates have been measured. The interference fringes were used to calculate the refractive index, thickness variation, average thickness and absorption coefficient ...

  7. Surface Chemistry of Nano-Structured Mixed Metal Oxide Films

    Science.gov (United States)

    2012-12-11

    dehydration . Steady-state reactive molecular beam scattering (RMBS) shows that dehydration is the dominant reaction pathway on clean Mo(1 1 0), while C–Mo(1 1...photoelectrochemical water oxidation performance under simulated solar irradiation of hematite (α-Fe2O3) films synthesized by coevaporation of pure Si and Fe

  8. Transparent conductive oxides for thin-film silicon solar cells

    NARCIS (Netherlands)

    Löffler, J.

    2005-01-01

    This thesis describes research on thin-film silicon solar cells with focus on the transparent conductive oxide (TCO) for such devices. In addition to the formation of a transparent and electrically conductive front electrode for the solar cell allowing photocurrent collection with low ohmic losses,

  9. Studies on tin oxide films prepared by electron beam evaporation ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Transparent conducting tin oxide thin films have been prepared by electron beam evaporation and spray pyrolysis methods. Structural, optical and electrical properties were studied under different pre- paration conditions like substrate temperature, solution flow rate and rate of deposition. Resistivity of un-.

  10. Electrical characterization of low temperature deposited oxide films ...

    Indian Academy of Sciences (India)

    Unknown

    Thin films of silicon dioxide are deposited on ZnO/n-Si substrate at a low temperature using tetra- ethylorthosilicate (TEOS). The ZnO/n-Si ... oxygen plasma has been extensively investigated because of its wide ranging applications in ... rapid electrical communication with the ZnO/n-Si sub- strate, whereas the oxide trapped ...

  11. Studies on tin oxide films prepared by electron beam evaporation ...

    Indian Academy of Sciences (India)

    Transparent conducting tin oxide thin films have been prepared by electron beam evaporation and spray pyrolysis methods. Structural, optical and electrical properties were studied under different preparation conditions like substrate temperature, solution flow rate and rate of deposition. Resistivity of undoped evaporated ...

  12. Optimized transparent and heat reflecting oxide and nitride films

    Energy Technology Data Exchange (ETDEWEB)

    Howson, R.P.; Ridge, M.I.; Suzuki, K.

    1984-11-01

    Films of indium oxide and indium oxide doped with tin have been produced by reactive planar magnetron sputtering of the pure metal and the alloy and from two metal sources simultaneously. In each case the oxygen partial pressure was controlled to give the higher sheet resistance in the oxide film which was deposited onto a plastic sheet transferred over a drum at ambient temperature. Films prepared under these conditions with the best properties for heat reflecting and visible transparent filters were found to be the oxide of the pure metal. A radio frequency discharge used in conjunction with the magnetron allowed the operating pressure to be considerably reduced, which allowed the preparation of titanium nitride films from a titanium metal target and the construction of simple metal and dielectric-metal-dielectric filters, which match theoretical predictions. A sandwich filter could be made from one titanium target by varying the active gas between oxygen and nitrogen to give a structure of: TiO/sub 2/-TiN-TiO/sub 2/. (A.V.)

  13. Chitosan–silver oxide nanocomposite film: Preparation and ...

    Indian Academy of Sciences (India)

    Chitosan; silver oxide; nanocomposite; antibacterial; film; food packaging. 1. ... food surface. Recently, antimicrobial packaging has emerged as one of the most reliable and promising tool in the search for the next generation of 'active' packaging (Salleh et al. 2007). ... Chitosan is the second most plentiful natural biopolymer.

  14. solution growth and characterization of copper oxide thin films ...

    African Journals Online (AJOL)

    Thin films of copper oxide (CuO) were grown on glass slides by using the solution growth technique. Copper cloride (CuCl ) and potassium telluride (K T O ) were used. Buffer 2 2e 3 solution was used as complexing agent. The solid state properties and optical properties were obtained from characterization done using PYE ...

  15. Investigation of the Carbon Monoxide Gas Sensing Characteristics of Tin Oxide Mixed Cerium Oxide Thin Films

    Directory of Open Access Journals (Sweden)

    Muhammad B. Haider

    2012-02-01

    Full Text Available Thin films of tin oxide mixed cerium oxide were grown on unheated substrates by physical vapor deposition. The films were annealed in air at 500 °C for two hours, and were characterized using X-ray photoelectron spectroscopy, atomic force microscopy and optical spectrophotometry. X-ray photoelectron spectroscopy and atomic force microscopy results reveal that the films were highly porous and porosity of our films was found to be in the range of 11.6–21.7%. The films were investigated for the detection of carbon monoxide, and were found to be highly sensitive. We found that 430 °C was the optimum operating temperature for sensing CO gas at concentrations as low as 5 ppm. Our sensors exhibited fast response and recovery times of 26 s and 30 s, respectively.

  16. Ferroelectric thin films using oxides as raw materials

    Directory of Open Access Journals (Sweden)

    E.B. Araújo

    1999-01-01

    Full Text Available This work describes an alternative method for the preparation of ferroelectric thin films based on pre-calcination of oxides, to be used as precursor material for a solution preparation. In order to show the viability of the proposed method, PbZr0.53Ti0.47O3 and Bi4Ti3O12 thin films were prepared on fused quartz and Si substrates. The results were analyzed by X-ray Diffraction (XRD, Scanning Electron Microscopy (SEM, Infrared Spectroscopy (IR and Rutherford Backscattering Spectroscopy (RBS. The films obtained show good quality, homogeneity and the desired stoichiometry. The estimated thickness for one layer deposition was approximately 1000 Å and 1500 Å for Bi4Ti3O12 and PbZr0.53Ti0.47O3 films, respectively.

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

    Science.gov (United States)

    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.

  18. Surface Morphology of Zinc Oxide Thin Films deposited by TCVD

    Science.gov (United States)

    Rafaie, H. A.; Noor, F. W. M.; Amizam, S.; Abdullah, S.; Rusop, M.

    2010-03-01

    Surface morphology study of Zinc Oxide (ZnO) thin films by using Thermal Chemical Vapor Deposition (Thermal-CVD) was investigated. The ZnO compound was synthesized from zinc acetate dehydrate which act as a starting material to form the ZnO thin films. It was deposited on as-prepared Nanonstructured Silicon (NSi) with deposition temperature ranging from 400-600° C without catalyst-assisted. The surface morphology of the samples before and after the deposition process was examined by using Analytical Scanning Electron Microscope (SEM). The result shows that the obtained ZnO thin films possess good crystalline structure at deposition temperature of 600° C and the surface morphologies of the ZnO thin films improved greatly with an increase in deposition temperature. XRD was employed to study the evolution of the crystalline orientation using X-Ray Diffractrometer (XRD).

  19. Structural transformation of nickel hydroxide films during anodic oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Crocker, Robert W. [Univ. of California, Berkeley, CA (United States); Muller, Rolf H. [Univ. of California, Berkeley, CA (United States)

    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.

  20. Structural transformation of nickel hydroxide films during anodic oxidation

    Energy Technology Data Exchange (ETDEWEB)

    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.

  1. Albumin adsorption on oxide thin films studied by spectroscopic ellipsometry

    Energy Technology Data Exchange (ETDEWEB)

    Silva-Bermudez, P., E-mail: suriel21@yahoo.com [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Circuito Exterior s/n, C.U., 04510, Mexico D.F. (Mexico); Unidad de Posgrado, Facultad de Odontologia, Universidad Nacional Autonoma de Mexico, CU, 04510, Mexico D.F. (Mexico); Rodil, S.E.; Muhl, S. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Circuito Exterior s/n, C.U., 04510, Mexico D.F. (Mexico)

    2011-12-15

    Thin films of tantalum, niobium, zirconium and titanium oxides were deposited by reactive magnetron sputtering and their wettability and surface energy, optical properties, roughness, chemical composition and microstructure were characterized using contact angle measurements, spectroscopic ellipsometry, profilometry, X-ray photoelectron spectroscopy and X-ray diffraction, respectively. The purpose of the work was to correlate the surface properties of the films to the Bovine Serum Albumin (BSA) adsorption, as a first step into the development of an initial in vitro test of the films biocompatibility, based on standardized protein adsorption essays. The films were immersed into BSA solutions with different protein concentrations and protein adsorption was monitored in situ by dynamic ellipsometry; the adsorption-rate was dependent on the solution concentration and the immersion time. The overall BSA adsorption was studied in situ using spectroscopic ellipsometry and it was found to be influenced by the wettability of the films; larger BSA adsorption occurred on the more hydrophobic surface, the ZrO{sub 2} film. On the Ta{sub 2}O{sub 5}, Nb{sub 2}O{sub 5} and TiO{sub 2} films, hydrophilic surfaces, the overall BSA adsorption increased with the surface roughness or the polar component of the surface energy.

  2. Tantalum oxide thin films as protective coatings for sensors

    DEFF Research Database (Denmark)

    Christensen, Carsten; Reus, Roger De; Bouwstra, Siebe

    1999-01-01

    Reactively sputtered tantalum oxide thin-films have been investigated as protective coating for aggressive media exposed sensors. Tantalum oxide is shown to be chemically very robust. The etch rate in aqueous potassium hydroxide with pH 11 at 140°C is lower than 0.008 Å/h. Etching in liquids with p......H values in the range from pH 2-11 have generally given etch rates below 0.04 Å/h. On the other hand patterning is possible in hydrofluoric acid. Further, the passivation behaviour of amorphous tantalum oxide and polycrystalline Ta2O5 is different in buffered hydrofluoric acid. By ex-situ annealing in O2...... the residual thin-film stress can be altered from compressive to tensile and annealing at 450°C for 30 minutes gives a stress-free film. The step coverage of the sputter deposited amorphous tantalum oxide is reasonable, but metallisation lines are hard to cover. Sputtered tantalum oxide exhibits high...

  3. Tantalum oxide thin films as protective coatings for sensors

    DEFF Research Database (Denmark)

    Christensen, Carsten; Reus, Roger De; Bouwstra, Siebe

    1999-01-01

    Reactively sputtered tantalum oxide thin films have been investigated as protective coatings for aggressive media exposed sensors. Tantalum oxide is shown to be chemically very robust. The etch rate in aqueous potassium hydroxide with pH 11 at 140°C is lower than 0.008 Å h-l. Etching in liquids...... with pH values in the range from pH 2 to 11 have generally given etch rates below 0.04 Å h-l. On the other hand patterning is possible in hydrofluoric acid. Further, the passivation behaviour of amorphous tantalum oxide and polycrystalline Ta2O5 is different in buffered hydrofluoric acid. By ex situ...... annealing O2 in the residual thin-film stress can be altered from compressive to tensile and annealing at 450°C for 30 minutes gives a stress-free film. The step coverage of the sputter deposited amorphous tantalum oxide is reasonable, but metallization lines are hard to cover. Sputtered tantalum oxide...

  4. Work Function Calculation For Hafnium- Barium System

    Directory of Open Access Journals (Sweden)

    K.A. Tursunmetov

    2015-08-01

    Full Text Available The adsorption process of barium atoms on hafnium is considered. A structural model of the system is presented and on the basis of calculation of interaction between ions dipole system the dependence of the work function on the coating.

  5. Calibration of the Lutetium-Hafnium Clock

    National Research Council Canada - National Science Library

    Erik Scherer; Carsten Münker; Klaus Mezger

    2001-01-01

    ... −1 , in agreement with the two most recent decay-counting experiments. Lutetium-hafnium ages that are based on the previously used λ 176 Lu of 1.93 × 10 −11 to 1.94 × 10 −11 year −1 are thus ∼4...

  6. The influence of Ac parameters in the process of micro-arc oxidation film electric breakdown

    Directory of Open Access Journals (Sweden)

    Ma Jin

    2016-01-01

    Full Text Available This paper studies the electric breakdown discharge process of micro-arc oxidation film on the surface of aluminum alloy. Based on the analysis of the AC parameters variation in the micro-arc oxidation process, the following conclusions can be drawn: The growth of oxide film can be divided into three stages, and Oxide film breakdown discharge occurs twice in the micro-arc oxidation process. The first stage is the formation and disruptive discharge of amorphous oxide film, producing the ceramic oxide granules, which belong to solid dielectric breakdown. In this stage the membrane voltage of the oxide film plays a key role; the second stage is the formation of ceramic oxide film, the ceramic oxide granules turns into porous structure oxide film in this stage; the third stage is the growth of ceramic oxide film, the gas film that forms in the oxide film’s porous structure is electric broken-down, which is the second breakdown discharge process, the current density on the oxide film surface could affect the breakdown process significantly.

  7. The Thickness Distribution of Oxidation Film on Tapered Pipe Surface in Dieless Drawing

    Directory of Open Access Journals (Sweden)

    Fang Qin

    2011-01-01

    Full Text Available The thickness distribution of oxidation film on the surface of AISI304 stainless steel tapered pipe, its influence factors, and the effect of metal matrix deformation on oxidation behavior during dieless drawing were studied in this paper. The results showed that oxidation rate was affected strongly by induction heating temperature and deformation degree. The thickness distribution of oxidation film was uneven and increased from the larger diameter end to the smaller diameter end along the axial direction of tapered pipe. When induction heating temperature raised or the distance between heat and cold sources was increased, or feed speed was decreased, oxidation rate was accelerated and oxidation film on the tapered pipe surface thickened significantly, due to massive cracks in oxidation film induced by deformation of metal matrix. The density and width of cracks in oxidation film were enlarged, and the thickness of oxidation film increased with the increase in deformation degree.

  8. Lubrication with Naturally Occurring Double Oxide Films

    Science.gov (United States)

    1982-11-10

    Friction Test with Metal Powders 24 7. Diagram of Metal Powder Test Specimen 24 R. Effect of Temperature on the Friction Coefficient for 28 CuPRe...that chronates would be produced as a result of its oxidation; more likely chromites (MeO. Cr203). Vanadium and boron are used in small amounts for...the frictional process in an alloy. The metal asperities would act as the basic alloy structure or as harder phases in that structure since it would

  9. Compositional analysis of silicon oxide/silicon nitride thin films

    Directory of Open Access Journals (Sweden)

    Meziani Samir

    2016-06-01

    Full Text Available Hydrogen, amorphous silicon nitride (SiNx:H abbreviated SiNx films were grown on multicrystalline silicon (mc-Si substrate by plasma enhanced chemical vapour deposition (PECVD in parallel configuration using NH3/SiH4 gas mixtures. The mc-Si wafers were taken from the same column of Si cast ingot. After the deposition process, the layers were oxidized (thermal oxidation in dry oxygen ambient environment at 950 °C to get oxide/nitride (ON structure. Secondary ion mass spectroscopy (SIMS, Rutherford backscattering spectroscopy (RBS, Auger electron spectroscopy (AES and energy dispersive X-ray analysis (EDX were employed for analyzing quantitatively the chemical composition and stoichiometry in the oxide-nitride stacked films. The effect of annealing temperature on the chemical composition of ON structure has been investigated. Some species, O, N, Si were redistributed in this structure during the thermal oxidation of SiNx. Indeed, oxygen diffused to the nitride layer into Si2O2N during dry oxidation.

  10. Structural and Electrochemical Properties of Lithium Nickel Oxide Thin Films

    Directory of Open Access Journals (Sweden)

    Gyu-bong Cho

    2014-01-01

    Full Text Available LiNiO2 thin films were fabricated by RF magnetron sputtering. The microstructure of the films was determined by X-ray diffraction and field-emission scanning electron microscopy. The electrochemical properties were investigated with a battery cycler using coin-type half-cells. The LiNiO2 thin films annealed below 500°C had the surface carbonate. The results suggest that surface carbonate interrupted the Li intercalation and deintercalation during charge/discharge. Although the annealing process enhanced the crystallization of LiNiO2, the capacity did not increase. When the annealing temperature was increased to 600°C, the FeCrNiO4 oxide phase was generated and the discharge capacity decreased due to an oxygen deficiency in the LiNiO2 thin film. The ZrO2-coated LiNiO2 thin film provided an improved discharge capacity compared to bare LiNiO2 thin film suggesting that the improved electrochemical characteristic may be attributed to the inhibition of surface carbonate by ZrO2 coating layer.

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

    Energy Technology Data Exchange (ETDEWEB)

    Chetna,, E-mail: chetna2288@gmail.com; Kumar, Shani; Chaudhary, S.; Kapoor, A. [Department of Electronic Science, University of Delhi South Campus, Benito Juarez Road, New Delhi-110021 (India); Garg, A.; Chowdhuri, A.; Dhingra, V. [Department of Electronic Science, Acharya Narendra Dev College, University of Delhi, Kalkaji, New Delhi- 110019 (India)

    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.

  12. Hafnium-an optical hydrogen sensor spanning six orders in pressure.

    Science.gov (United States)

    Boelsma, C; Bannenberg, L J; van Setten, M J; Steinke, N-J; van Well, A A; Dam, B

    2017-06-05

    Hydrogen detection is essential for its implementation as an energy vector. So far, palladium is considered to be the most effective hydrogen sensing material. Here we show that palladium-capped hafnium thin films show a highly reproducible change in optical transmission in response to a hydrogen exposure ranging over six orders of magnitude in pressure. The optical signal is hysteresis-free within this range, which includes a transition between two structural phases. A temperature change results in a uniform shift of the optical signal. This, to our knowledge unique, feature facilitates the sensor calibration and suggests a constant hydrogenation enthalpy. In addition, it suggests an anomalously steep increase of the entropy with the hydrogen/metal ratio that cannot be explained on the basis of a classical solid solution model. The optical behaviour as a function of its hydrogen content makes hafnium well-suited for use as a hydrogen detection material.

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

    Science.gov (United States)

    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. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Development of thickness measurement program for transparent conducting oxide thin films

    OpenAIRE

    Mitsugi, Fumiaki; Matsuoka, Aya; Umeda, Yoshihiro; Ikegami, Tomoaki; ミツギ, フミアキ; マツオカ, アヤ; ウメダ, ヨシヒロ; イケガミ, トモアキ; 光木, 文秋; 松岡, 綾; 梅田, 佳宏; 池上, 知顯

    2010-01-01

    The gallium doped zinc oxide has been one of the candidates for the transparent conducting oxide thin film electrode. It is not suitable to use a conventional light interference method to measure the thickness of the gallium doped zinc oxide thin film because the refractive index and extinction coefficient of the thin film is unknown during the optimization of the deposition conditions. In this paper, we report on the details of the film thickness program which uses the measured optical and e...

  15. PHOTOELECTRIC AND PHOTOMAGNETIC RESPONSE OF INDIUM-TIN OXIDE FILMS

    Directory of Open Access Journals (Sweden)

    I. K. Meshkovsky

    2015-11-01

    Full Text Available Subject of Research. The goal of the present research is investigation of photoelectric and photomagnetic response of ITO (indium-tin oxide films under UV laser irradiation. Method. The ITO films were prepared by magnetron sputtering with the thickness equal to 300nm. The films were irradiated by UV laser light with 248 nm wavelength in laser pulse energy range from 10 mJ to 150 mJ by KrF excimer laser. Metallic electrodes were deposited on the films. Information about the films surface topography was obtained by atomic force microscopy and scanning electron microscopy. The film structure was investigated by X-ray diffraction. Main Results. It was shown that voltage appears between metallic contacts under the UV light effect. The electric current was observed through resistive load. The anisotropy of electric field producing photoelectric response was demonstrated for the first time. The appearance of magnetic field under the laser light irradiation was observed for the first time. The dependence of the response voltage on the laser pulse energy was linear over the whole measured energy range. The following physical mechanism was proposed for description of the observed phenomenon: electric voltage is associated with non-uniform distribution of the average crystallite size along the film surface, and, therefore, with mean free path of the charge carriers along the film surface. Photomagnetic response could be associated with collective behavior of the large number of charged particles, created due to high intensity laser irradiation. Practical Relevance. The phenomenon being studied could be applied for creation of new optoelectronic devices, for example, modulators, optical detectors, etc. Particularly, due to linear dependence of photoelectric response on the laser pulse energy, this phenomenon is attractive for manufacturing of simple and cheap excimer laser pulse energy detectors.

  16. Unusual hydrogen peroxide decomposition on stoichiometric insulating oxide ultrathin films

    CERN Document Server

    Song, Zhenjun

    2016-01-01

    The hydrogen peroxide dissociation on MgO(001) films deposited on Mo(001) surface is investigated by employing periodic density-functional theory methods. The pristine MgO(001) surface showing chemical inertness prefers the weak adsorbing molecular configuration and is extremely difficult to react with hydrogen peroxide. As far as we know, energetically favorable decomposition state of hydrogen peroxide has never been obtained on MgO(001) surface. In this work the hydrogen peroxide is successfully dissociated on perfect stoichiometric MgO(001) films by depositing on transition metal substrate, without any activation barrier. The spontaneous dissociation of hydrogen peroxide on metal supported oxide films is rationalized by characterizing the geometric structures and electronic structures.

  17. Tunable Nanostructures and Crystal Structures in Titanium Oxide Films

    Directory of Open Access Journals (Sweden)

    Fuess H

    2008-01-01

    Full Text Available Abstract 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.

  18. Properties of indium oxide/tin oxide multilayered films prepared by ion-beam sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Takeyuki; Yamazaki, Tsutomu; Oda, Harunobu

    1988-08-01

    The preparation and characterization of indium oxide (InOsub(x))/tin oxide (SnOsub(y)) multilayered films deposited by ion-beam sputtering are described and compared with indium tin oxide (ITO) films. The structure and the optoelectrical properties of the films are studied in relation to the layered structures and the post-deposition annealing. Low-angle X-ray diffraction analysis showed that most films retained the regular layered structures even after annealing at 500/sup 0/C for 16 h. As an example, we obtained a resistivity of 6 x 10/sup -4/ ..cap omega.. cm and a transparency of about 85% in the visible range at a thickness of 110 nm in a multilayered film of InOsub(x) (2.0 nm)/SnOsub(y) (0.2 nm) x 50 pairs when annealed at 300/sup 0/C for 0.5 h in air. Hall coefficient measurements showed that this film had a mobility of 17 cm/sup 2/ V/sup -1/ sec/sup -1/ and a carrier concentration (electron density) of 5 x 10/sup 20/ cm/sup -3/.

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

    Science.gov (United States)

    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.

  20. Reduction of graphene oxide and its effect on square resistance of reduced graphene oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Zhaoxia; Zhou, Yin; Li, Guang Bin; Wang, Shaohong; Wang, Mei Han; Hu, Xiaodan; Li, Siming [Liaoning Province Key Laboratory of New Functional Materials and Chemical Technology, School ofMechanical Engineering, Shenyang University, Shenyang (China)

    2015-06-15

    Graphite oxide was prepared via the modified Hummers’ method and graphene via chemical reduction. Deoxygenation efficiency of graphene oxide was compared among single reductants including sodium borohydride, hydrohalic acids, hydrazine hydrate, and vitamin C. Two-step reduction of graphene oxide was primarily studied. The reduced graphene oxide was characterized by XRD, TG, SEM, XPS, and Raman spectroscopy. Square resistance was measured as well. Results showed that films with single-step N2H4 reduction have the best transmittance and electrical conductivity with square resistance of ~5746 Ω/sq at 70% transmittance. This provided an experimental basis of using graphene for electronic device applications.

  1. Metal oxide films on glass and steel substrates

    CERN Document Server

    Sohi, A M

    1987-01-01

    in the pH8 electrolyte supports the view that the rate limiting reduction reaction is possibly oxygen (or water) reduction although some contribution from an organic 'impurity' cannot be ruled out. Coatings of Fe sub 3 O sub 4 on mild steel have been prepared by CVD using pneumatic spraying techniques and the corrosion behaviour of coated electrodes in organic-phosphate electrolyte (pH8) has been examined. A variety of thin (10-1000nm) metal oxide films have been deposited on flat glass substrates by the pyrolysis of an aerosol of metal acetylacetonates in a suitable carrier. The optical characteristics and thickness of the films have been measured and particular interest has centered on the use of a novel pin on disc apparatus to measure the physical durability of such thin films. Characteristic friction/penetration force traces have been established for 1st Series transition metal oxide films and some ranking in terms of 'hardness' established. The use of SnO sub 2 - coated glass for electrodes in a light m...

  2. Photocatalytic oxide films in the built environment

    Science.gov (United States)

    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.

  3. Multiferroic iron oxide thin films at room temperature.

    Science.gov (United States)

    Gich, Martí; Fina, Ignasi; Morelli, Alessio; Sánchez, Florencio; Alexe, Marin; Gàzquez, Jaume; Fontcuberta, Josep; Roig, Anna

    2014-07-16

    Multiferroic behaviour at room temperature is demonstrated in ε-Fe2 O3 . The simple composition of this new ferromagnetic ferroelectric oxide and the discovery of a robust path for its thin film growth by using suitable seed layers may boost the exploitation of ε-Fe2 O3 in novel devices. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Strain-induced phenomenon in complex oxide thin films

    Science.gov (United States)

    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. Thermal oxidation of Ni films for p-type thin-film transistors

    KAUST Repository

    Jiang, Jie

    2013-01-01

    p-Type nanocrystal NiO-based thin-film transistors (TFTs) are fabricated by simply oxidizing thin Ni films at temperatures as low as 400 °C. The highest field-effect mobility in a linear region and the current on-off ratio are found to be 5.2 cm2 V-1 s-1 and 2.2 × 103, respectively. X-ray diffraction, transmission electron microscopy and electrical performances of the TFTs with "top contact" and "bottom contact" channels suggest that the upper parts of the Ni films are clearly oxidized. In contrast, the lower parts in contact with the gate dielectric are partially oxidized to form a quasi-discontinuous Ni layer, which does not fully shield the gate electric field, but still conduct the source and drain current. This simple method for producing p-type TFTs may be promising for the next-generation oxide-based electronic applications. © 2013 the Owner Societies.

  6. The synthesis and characterization of multifunctional oxide thin films

    Science.gov (United States)

    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

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

    Directory of Open Access Journals (Sweden)

    Alfons Penzkofer

    2012-07-01

    Full Text Available 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.

  8. Temperature Effects on a-IGZO Thin Film Transistors Using HfO2 Gate Dielectric Material

    Directory of Open Access Journals (Sweden)

    Yu-Hsien Lin

    2014-01-01

    Full Text Available This study investigated the temperature effect on amorphous indium gallium zinc oxide (a-IGZO thin film transistors (TFTs using hafnium oxide (HfO2 gate dielectric material. HfO2 is an attractive candidate as a high-κ dielectric material for gate oxide because it has great potential to exhibit superior electrical properties with a high drive current. In the process of integrating the gate dielectric and IGZO thin film, postannealing treatment is an essential process for completing the chemical reaction of the IGZO thin film and enhancing the gate oxide quality to adjust the electrical characteristics of the TFTs. However, the hafnium atom diffused the IGZO thin film, causing interface roughness because of the stability of the HfO2 dielectric thin film during high-temperature annealing. In this study, the annealing temperature was optimized at 200°C for a HfO2 gate dielectric TFT exhibiting high mobility, a high ION/IOFF ratio, low IOFF current, and excellent subthreshold swing (SS.

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

    Science.gov (United States)

    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.

  10. Amorphous nickel incorporated tin oxide thin film transistors

    Science.gov (United States)

    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.

  11. Organic thin film transistors with indium tin oxide bottom electrode

    Energy Technology Data Exchange (ETDEWEB)

    Han, Chang-Wook [School of Electrical Engineering 50, Seoul National University, Shinlim-dong, Gwanak-gu, Seoul 151-742 (Korea, Republic of); Shin, Hee-Sun [School of Electrical Engineering 50, Seoul National University, Shinlim-dong, Gwanak-gu, Seoul 151-742 (Korea, Republic of); Park, Joong-Hyun [School of Electrical Engineering 50, Seoul National University, Shinlim-dong, Gwanak-gu, Seoul 151-742 (Korea, Republic of); Han, Min-Koo [School of Electrical Engineering 50, Seoul National University, Shinlim-dong, Gwanak-gu, Seoul 151-742 (Korea, Republic of); Pang, Hee-Suk [LG.PHILIPS LCD R and D Center 533 Anyang-shi, Gyongki-do 431-080 (Korea, Republic of); Kim, Ki-Yong [LG.PHILIPS LCD R and D Center 533 Anyang-shi, Gyongki-do 431-080 (Korea, Republic of); Chung, In-Jae [LG.PHILIPS LCD R and D Center 533 Anyang-shi, Gyongki-do 431-080 (Korea, Republic of); Pyo, Sang-Woo [Department of Electrical Information and Control Engineering, Hongik University (Korea, Republic of); Lee, Dong-Hyun [Department of Information Display Engineering, Hongik University (Korea, Republic of); Kim, Young-Kwan [Department of Information Display Engineering, Hongik University (Korea, Republic of)

    2006-09-01

    Organic thin film transistors (OTFTs) which employ indium tin oxide (ITO) as source and drain electrodes instead of gold are fabricated. A double gate dielectric layer was used, which consists of benzocyclobutane (BCB) and silicon nitride (SiN{sub x}). The pentacene TFT has lateral dimensions 192 {mu}mx6 {mu}m. The OTFT with the ITO bottom electrode shows a saturation mobility of 0.05{approx}0.09 cm{sup 2} V{sup -1} s{sup -1} and an on-off current ratio of the order of 10{sup 5} in a gate voltage span between 0 and -40 V. The TFT fabrication process steps had the beneficial side effect of changing the ITO surface from hydrophilic to hydrophobic. This change allows pentacene films with larger grains, observed up to 0.5 {mu}m, to be grown on TFT compared to as-deposited ITO film onto which high quality films cannot be grown.

  12. Hafnium implanted in iron 1. Lattice location and annealing behavior

    NARCIS (Netherlands)

    de Bakker, J.M.G.J.; Pleiter, F; Smulders, P.J M

    1993-01-01

    Perturbed angular correlation, Rutherford backscattering and channelling experiments were conducted to study the lattice location and annealing behaviour of 110 keV hafnium ions implanted into iron single crystals. It was found that a fraction of 11-25% of the implanted hafnium atoms are located at

  13. Conductivity and thermoelectric properties of nanostructure tin oxide thin films

    Directory of Open Access Journals (Sweden)

    M.A. Batal

    2014-04-01

    Full Text Available Tin oxide thin films doped with iron or copper were deposited on glass and porous alumina substrates, using the co-deposition dip coating sol–gel technique. Alumina substrate was prepared by the anodizing technique. Samples were sintered for 2 h at temperature 600 °C. The XRD spectrum of deposited samples shows a polycrystalline structure with a clear characteristic peak of SnO2 cassiterite phase. From (I–V characteristics measured at different temperatures for samples prepared on glass substrates, the density of states at the Fermi level was calculated. Thermoelectric effect was measured with a change of temperature for prepared samples under low pressure 1 mbar. Seebeck coefficient, the carrier concentration, the charge carrier mobility and the figure merit were determined for prepared samples under low pressure 1 mbar. Seebeck coefficient was improved when films were deposited on porous Alumina substrates.

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

    Science.gov (United States)

    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.

  15. Structure and morphology of ultrathin iron and iron oxide films on Ag(001)

    Energy Technology Data Exchange (ETDEWEB)

    Bruns, Daniel

    2012-10-15

    This work investigates the initial growth of iron and iron oxides on Ag(001). Surface structure and morphology of both post deposition annealed Fe films (in UHV and O{sub 2} atmosphere) as well as reactive grown iron oxide films will be analyzed in detail by low energy electron diffraction (LEED) and scanning tunneling microscopy (STM). The stoichiometry at the surface of the iron oxide films is determined by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). The main focus of this work is to shed light on the question whether the growth of iron oxide films on Ag(001) is accompanied by the formation of strain reducing dislocation networks, or superstructures as found for other metal substrates in former studies. Here, we distinguish between Fe films which were post deposition annealed in a thin O{sub 2} atmosphere and reactively grown iron oxide films.

  16. Nanoscale reduction of graphene oxide thin films and its characterization

    KAUST Repository

    Lorenzoni, M.

    2015-06-29

    In this paper, we report on a method to reduce thin films of graphene oxide (GO) to a spatial resolution better than 100 nm over several tens of micrometers by means of an electrochemical scanning probe based lithography. In situ tip-current measurements show that an edged drop in electrical resistance characterizes the reduced areas, and that the reduction process is, to a good approximation, proportional to the applied bias between the onset voltage and the saturation thresholds. An atomic force microscope (AFM) quantifies the drop of the surface height for the reduced profile due to the loss of oxygen. Complementarily, lateral force microscopy reveals a homogeneous friction coefficient of the reduced regions that is remarkably lower than that of native graphene oxide, confirming a chemical change in the patterned region. Micro Raman spectroscopy, which provides access to insights into the chemical process, allows one to quantify the restoration and de-oxidation of the graphitic network driven by the electrochemical reduction and to determine characteristic length scales. It also confirms the homogeneity of the process over wide areas. The results shown were obtained from accurate analysis of the shift, intensity and width of Raman peaks for the main vibrational bands of GO and reduced graphene oxide (rGO) mapped over large areas. Concerning multilayered GO thin films obtained by drop-casting we have demonstrated an unprecedented lateral resolution in ambient conditions as well as an improved control, characterization and understanding of the reduction process occurring in GO randomly folded multilayers, useful for large-scale processing of graphene-based material. © 2015 IOP Publishing Ltd.

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

    Science.gov (United States)

    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.

  18. Spray Pyrolyzed Polycrystalline Tin Oxide Thin Film as Hydrogen Sensor

    Directory of Open Access Journals (Sweden)

    Ganesh E. Patil

    2010-09-01

    Full Text Available Polycrystalline tin oxide (SnO2 thin film was prepared by using simple and inexpensive spray pyrolysis technique (SPT. The film was characterized for their phase and morphology by X-ray diffraction (XRD and scanning electron microscopy (SEM, respectively. The crystallite size calculated from the XRD pattern is 84 nm. Conductance responses of the polycrystalline SnO2 were measured towards gases like hydrogen (H2, liquefied petroleum gas (LPG, ethanol vapors (C2H5OH, NH3, CO, CO2, Cl2 and O2. The gas sensing characteristics were obtained by measuring the sensor response as a function of various controlling factors like operating temperature, operating voltages (1 V, 5 V, 10 V 15 V, 20 V and 25 V and concentration of gases. The sensor response measurement showed that the SnO2 has maximum response to hydrogen. Furthermore; the SnO2 based sensor exhibited fast response and good recovery towards hydrogen at temperature 150 oC. The result of response towards H2 reveals that SnO2 thin film prepared by SPT would be a suitable material for the fabrication of the hydrogen sensor.

  19. Electrochromic Devices Based on Porous Tungsten Oxide Thin Films

    Directory of Open Access Journals (Sweden)

    Y. Djaoued

    2012-01-01

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

  20. Oxidation kinetics of metal films and diffusion in NiO for data storage

    OpenAIRE

    Unutulmazsoy, Yeliz

    2016-01-01

    The growth of pore-free oxide layers on metals is determined by formation and migration of point defects and thus is an issue of fundamental importance. So far, mainly oxidation kinetics of thick metal films, crystals, and bulk samples were investigated in the literature. The oxidation of thin metal films on insulating substrates can easily be monitored by measuring the conductivity of the remaining metal. This dissertation focuses on understanding the processes that determine the oxide growt...

  1. Transparent conductive oxide thin films of tungsten-doped indium oxide

    Energy Technology Data Exchange (ETDEWEB)

    Li Xifeng [Department of Materials Science, Fudan University, Shanghai 200433 (China); Zhang Qun [Department of Materials Science, Fudan University, Shanghai 200433 (China)]. E-mail: zhangqun@fudan.edu.cn; Miao Weina [Department of Materials Science, Fudan University, Shanghai 200433 (China); Huang Li [Department of Materials Science, Fudan University, Shanghai 200433 (China); Zhang Zhuangjian [Department of Materials Science, Fudan University, Shanghai 200433 (China)

    2006-12-05

    Transparent conductive oxide thin film of tungsten-doped In{sub 2}O{sub 3} (IWO) has been prepared by reactive direct current magnetron sputtering from the tungsten-embedded indium metal target. The effect of tungsten doping content on the optoelectrical properties of IWO films was investigated. The lowest resistivity of 2.7 x 10{sup -4} {omega}.cm was reproducibly obtained, with carrier mobility greater than 57 cm{sup 2} V{sup -1} s{sup -1} and carrier concentration of 4.0 x 10{sup 20} cm{sup -3}, as well as the transmission in visible light range exceeding 80%. X-ray diffraction measurements indicate that the as-deposited IWO films are well crystallized with a preferential orientation of (222)

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

    Energy Technology Data Exchange (ETDEWEB)

    Meng Na; Zhou Ninglin; Shen Jian [Jiangsu Engineering Research Center for Biomedical Function Materials, Nanjing Normal University, Nanjing 210046 (China); Zhang Shuangquan, E-mail: zhouninglin@njnu.edu.cn, E-mail: jshen@njnu.edu.cn, E-mail: shuangquanz@yahoo.com [Jiangsu Province Key Laboratory for Molecular and Medical Biotechnology, Life Sciences College, Nanjing Normal University, Nanjing 210046 (China)

    2010-05-07

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2010-05-07

    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.

  5. Surface plasmon resonance biochip based on ZnO thin film for nitric oxide sensing.

    Science.gov (United States)

    Feng, Wei-Yi; Chiu, Nan-Fu; Lu, Hui-Hsin; Shih, Hsueh-Ching; Yang, Dongfang; Lin, Chii-Wann

    2008-01-01

    In this study, the design of a novel optical sensor that comprises surface plasmon resonance sensing chip and zinc oxide nano-film was proposed for the detection of nitric oxide gas. The electrical and optical properties of zinc oxide film vary in the presence of nitric oxide. This effect was utilized to prepare biochemical sensors with transduction based on surface plasmon resonance. Due to the refractive index of the transparent zinc oxide film that was deposited on the gold film, however, changes will be observed in the surface plasmon resonance spectra. For this reason, the thickness of zinc oxide film will be investigated and determined in this study. The interaction of nitric oxide with a 20 nm zinc oxide layer on gold leads to the shift of the resonance angle. The analysis on the reflectance intensity of light demonstrates that such effect is caused by the variation of conductivity and permittivity of zinc oxide film. Finally, a shift in surface plasmon resonance angle was measured in 25 ppm nitric oxide at 180 C and a calibration curve of nitride oxide concentration versus response intensity was successfully obtained in the range of 250 to 1000 ppm nitric oxide at lower temperature of 150 C. Moreover, these effects are quasi-reversible.

  6. An amorphous oxide semiconductor thin-film transistor route to oxide electronics

    OpenAIRE

    Wager, John F.; Yeh, Bao; Hoffman, Randy L.; Keszler, Douglas A.

    2014-01-01

    Amorphous oxide semiconductor (AOS) thin-film transistors (TFTs) invented only one decade ago are now being commercialized for active-matrix liquid crystal display (AMLCD) backplane applications. They also appear to be well positioned for other flat-panel display applications such as active-matrix organic light-emitting diode (AMOLED) applications, electrophoretic displays, and transparent displays. The objectives of this contribution are to overview AOS materials design; assess indium galliu...

  7. 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.

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Jisheng [Iowa State Univ., Ames, IA (United States)

    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.

  9. Solution-Processed Gallium–Tin-Based Oxide Semiconductors for Thin-Film Transistors

    Directory of Open Access Journals (Sweden)

    Xue Zhang

    2017-12-01

    Full Text Available We investigated the effects of gallium (Ga and tin (Sn compositions on the structural and chemical properties of Ga–Sn-mixed (Ga:Sn oxide films and the electrical properties of Ga:Sn oxide thin-film transistors (TFTs. The thermogravimetric analysis results indicate that solution-processed oxide films can be produced via thermal annealing at 500 °C. The oxygen deficiency ratio in the Ga:Sn oxide film increased from 0.18 (Ga oxide and 0.30 (Sn oxide to 0.36, while the X-ray diffraction peaks corresponding to Sn oxide significantly reduced. The Ga:Sn oxide film exhibited smaller grains compared to the nanocrystalline Sn oxide film, while the Ga oxide film exhibited an amorphous morphology. We found that the electrical properties of TFTs significantly improve by mixing Ga and Sn. Here, the optimum weight ratio of the constituents in the mixture of Ga and Sn precursor sols was determined to be 1.0:0.9 (Ga precursor sol:Sn precursor sol for application in the solution-processed Ga:Sn oxide TFTs. In addition, when the Ga(1.0:Sn(0.9 oxide film was thermally annealed at 900 °C, the field-effect mobility of the TFT was notably enhanced from 0.02 to 1.03 cm2/Vs. Therefore, the mixing concentration ratio and annealing temperature are crucial for the chemical and morphological properties of solution-processed Ga:Sn oxide films and for the TFT performance.

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

    Indian Academy of Sciences (India)

    For the fabrication of miniature heater indium tin oxide thin film was grown on special high temperature corning glass substrate by flash evaporation method. Gold was deposited on the film using thermal evaporation technique under high vacuum. The film was then annealed at 700 K for an hour. The thermocouple attached ...

  11. Adsorbsi Hafnium (Hf) Dalam Resin Penukar Anion Dowex-1x8 Adsorbtion of Hafnium (Hf) in Dowex - 1x8 Anion Exchange Resin

    OpenAIRE

    Susiantini, Endang; Setyadji, Moch

    2014-01-01

    Hafnium memiliki titik lebur yang tinggi dan kemampuan menyerap neutron per luas penampang 600 kali lebih besar dari Zr sehingga berpotensi untuk dimanfaatkan sebagai salah satu bahan batang pengendali reaksi fisi nuklir. Berbagai metode pemurnian Hf dari Zr telah dikembangkan salah satunya adalah dengan menggunakan resin penukar ion. Pada penelitian ini digunakan umpan berbentuk sulfat dari hafnium murni dan hafnium-zirkonium campuran hasil proses pengolahan pasir zirkon. Umpan hafnium sulfa...

  12. Electrosprayed Metal Oxide Semiconductor Films for Sensitive and Selective Detection of Hydrogen Sulfide

    NARCIS (Netherlands)

    Ghimbeu, C.M.; Lumbreras, M.; Schoonman, J.; Siadat, M.

    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

  13. Room temperature transparent conducting oxides based on zinc oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Clatot, J. [Laboratoire de Reactivite et de Chimie des Solides, UMR CNRS 6007, 33, rue Saint-Leu, 80039 Amiens (France); Campet, G. [Institut de Chimie de la Matiere Condensee de Bordeaux (ICMCB), CNRS, 87 Avenue du Docteur A. Schweitzer, 33608 Pessac Cedex (France); Zeinert, A. [Laboratoire de Physique de la Matiere Condensee, Universite de Picardie Jules Verne, 33 rue St. Leu, 80039, Amiens (France); Labrugere, C. [Institut de Chimie de la Matiere Condensee de Bordeaux (ICMCB), CNRS, 87 Avenue du Docteur A. Schweitzer, 33608 Pessac Cedex (France); Rougier, A., E-mail: aline.rougier@u-picardie.fr [Laboratoire de Reactivite et de Chimie des Solides, UMR CNRS 6007, 33, rue Saint-Leu, 80039 Amiens (France)

    2011-04-01

    Doped zinc oxide thin films are grown on glass substrate at room temperature under oxygen atmosphere, using pulsed laser deposition (PLD). O{sub 2} pressure below 1 Pa leads to conductive films. A careful characterization of the film stoichiometry and microstructure using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) concludes on a decrease in crystallinity with Al and Ga additions ({<=}3%). The progressive loss of the (0 0 2) orientation is associated with a variation of the c parameter value as a function of the film thickness and substrate nature. ZnO:Al and ZnO:Ga thin films show a high optical transmittance (>80%) with an increase in band gap from 3.27 eV (pure ZnO) to 3.88 eV and 3.61 eV for Al and Ga doping, respectively. Optical carrier concentration, optical mobility and optical resistivity are deduced from simulation of the optical data.

  14. Optical and structural characterization of iron oxide and cobalt oxide thin films at 800 nm

    Science.gov (United States)

    Garcia, Hans A.; de Melo, Ronaldo P.; Azevedo, Antonio; de Araújo, Cid B.

    2013-05-01

    We report on optical and structural properties of α-Fe2O3 and Co3O4 thin films, grown by direct oxidation of pure metal films deposited on soda-lime glass. Structural characteristics and morphology of the films were investigated by X-ray diffraction, atomic force microscopy, and scanning electron microscopy. Linear optical absorption, and linear refraction as well as nonlinear optical properties were investigated. The third-order optical susceptibilities were measured applying the Thermally managed Z- scan technique using a Ti: sapphire laser (150 fs; 800 nm). The results obtained for the Co3O4 film were {Re} χ^{( 3 )} = -(5.7 ± 2.4) ×10-9 esu and {Im} χ^{(3)} = -(1.8 ± 0.2) ×10-8 esu while for the α-Fe2O3 film we determined {Re} χ^{(3)} = +(6.6 ± 2.4) ×10-10 esu and {Im} χ^{(3)} = +(2.2 ± 0.4) ×10-10 esu.

  15. Development of analytical method for microstructure observation of oxide film on stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Nemoto, Yoshiyuki; Miwa, Yukio; Tsukada, Takashi; Kikuchi, Masahiko; Tsuji, Hirokazu [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-12-01

    Development and research about analytical method for the study of oxide film on austenitic stainless steel had been conducted from the point of view for basic study of IASCC (Irradiation Assisted Stress Corrosion Cracking). Nickel plating and copper plating had been compared as the oxide film protection while the fabrication for cross sectional observation. And thin film specimens for microstructural observation were fabricated using FIB (Focused Ion Beam) technique. Microstructure of oxide film on stainless steel had been observed with FE-TEM (Field Emission gun - Transmission Electron Microscope), and the chemical composition was analyzed with EDS (Energy dispersed X-ray Spectrometer). The oxide film had been formed in high pressure (8 MPa) and high temperature (288degC) water, contains saturated oxygen. The thickness of oxide film was about 1 {mu}m as maximum. Micro grains of Fe oxide with 100 nm in diameter were formed in the oxide film. On the boundary with alloy, there was about 10 nm thickness of passive film formed with Cr oxide. (author)

  16. Transparent conducting zinc oxide thin film prepared by off-axis rf ...

    Indian Academy of Sciences (India)

    Unknown

    transitions is known as Burstein–Moss effect (Roth et al. 1982; Sernelius et al 1988). 4. Conclusions. Undoped zinc oxide and aluminum doped zinc oxide films were prepared by rf magnetron sputtering of pre- synthesized target. All the films exhibit a transmission of over 85% in the visible region. The electrical resistivity.

  17. Oxidation kinetics of nanoscale copper films studied by terahertz transmission spectroscopy

    NARCIS (Netherlands)

    Ramanandan, G.K.P.; Ramakrishnan, G.; Planken, P.C.M.

    2012-01-01

    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.

  18. Growth and Dissolution of Iron and Manganese Oxide Films

    Energy Technology Data Exchange (ETDEWEB)

    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

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

    Science.gov (United States)

    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

  20. The Effect of Cr Content on the Oxidation Behavior of Ti-Cr-N Films

    Directory of Open Access Journals (Sweden)

    James E. Krzanowski

    2014-04-01

    Full Text Available Ti1−xCrxN thin-film samples were sputter-deposited with lateral composition gradients x = 0.1–0.9 across each sample. In order to determine the effect of Cr content on oxidation, samples were air-oxidized at temperatures ranging from 650 to 950 °C. The extent and type of oxide formed was characterized using X-ray diffraction. Only minor oxidation was observed for the 650–750 °C temperature range. At 850 °C, films below x = 0.7 showed poor oxidation resistance, with the formation of TiO2 and Cr2O3 oxides, but little oxidation occurred above x = 0.7. At 950 °C, films above x = 0.7 again exhibited the best oxidation resistance. Chromium nitride films, which deposited as Cr2N, were found to begin oxidizing at 750 °C, indicating that the increased oxidation resistance of the higher-Cr Ti-Cr-N films can be attributed to the Ti-induced stabilization of the B1-structured phase. A compositionally-uniform film (x = 0.79 was also deposited and analyzed by XPS before and after oxidation. Oxidation resulted in primarily Cr2O3 at the surface, with some TiO2 also present, with the oxide richer in Cr than the starting film composition. These results suggested that at higher Cr compositions in the film, the oxidation mechanism was controlled by Cr diffusion to the surface.

  1. Study of thin oxide films by electron, ion and synchrotron radiation beams

    CERN Document Server

    Sammelselg, V; Tarre, A; Asari, J; Rauhala, E; Arstila, K; Seppaelae, A; Zakharov, A; Aarik, J; Karlis, J; Martinson, Indrek

    2002-01-01

    Titanium oxide and zirconium oxide thin films deposited on silicon substrates were characterized using electron probe microanalysis (EPMA), Rutherford backscattering spectroscopy (RBS), time-of-flight elastic recoil detection analysis (TOF-ERDA) and scanning photoelectron microscopy (SPEM). The composition and mass thickness of the films were determined and the results of different methods compared. lt was revealed that the synchrotron radiation used for SPEM studies caused considerable modification of zirconia films grown at low temperatures. (author)

  2. Uniformity of gallium doped zinc oxide thin film prepared by pulsed laser deposition

    OpenAIRE

    Mitsugi, Fumiaki; Umeda, Yoshihiro; Sakai, Norihiro; Ikegami, Tomoaki; ミツギ, フミアキ; ウメダ, ヨシヒロ; サカイ, ノリヒロ; イケガミ, トモアキ; 光木, 文秋; 梅田, 佳宏; 坂井, 徳浩; 池上, 知顯

    2010-01-01

    Recently, transparent conducting oxide thin films have attracted attention for the application to transparent conducting electrodes. In this work, we evaluated the uniformity of electrical, optical and structural properties for gallium doped zinc oxide thin films prepared on the 10 × 10 cm2 silica glass substrate by pulsed laser deposition. The resistivity, carrier concentration, mobility, bonding state and atomic composition of the film were uniform along in-plane and depth direction over th...

  3. Raman and XPS characterization of vanadium oxide thin films with temperature

    Energy Technology Data Exchange (ETDEWEB)

    Ureña-Begara, Ferran, E-mail: ferran.urena@uclouvain.be [Université catholique de Louvain, Institute of Information and Communication Technologies, Electronics and Applied Mathematics (ICTEAM), Louvain-la-Neuve (Belgium); Crunteanu, Aurelian [XLIM Research Institute, UMR 7252, CNRS/Université de Limoges, Limoges (France); Raskin, Jean-Pierre [Université catholique de Louvain, Institute of Information and Communication Technologies, Electronics and Applied Mathematics (ICTEAM), Louvain-la-Neuve (Belgium)

    2017-05-01

    Highlights: • Comprehensive study of the oxidation of VO{sub 2} thin films from R.T. up to 550 °C. • Phase changes and mixed-valence vanadium oxides formed during the oxidation process. • Reported Raman and XPS signatures for each vanadium oxide. • Monitoring of the current and resistance evolution at the surface of the films. • Oxidation model describing the evolution of the vanadium oxides and phase changes. - Abstract: The oxidation mechanisms and the numerous phase transitions undergone by VO{sub 2} thin films deposited on SiO{sub 2}/Si and Al{sub 2}O{sub 3} substrates when heated from room temperature (R.T.) up to 550 °C in air are investigated by Raman and X-ray photoelectron spectroscopy. The results show that the films undergo several intermediate phase transitions between the initial VO{sub 2} monoclinic phase at R.T. and the final V{sub 2}O{sub 5} phase at 550 °C. The information about these intermediate phase transitions is scarce and their identification is important since they are often found during the synthesis of vanadium dioxide films. Significant changes in the film conductivity have also been observed to occur associated to the phase transitions. In this work, current and resistance measurements performed on the surface of the films are implemented in parallel with the Raman measurements to correlate the different phases with the conductivity of the films. A model to explain the oxidation mechanisms and phenomena occurring during the oxidation of the films is proposed. Peak frequencies, full-width half-maxima, binding energies and oxidation states from the Raman and X-ray photoelectron spectroscopy experiments are reported and analyzed for all the phases encountered in VO{sub 2} films prepared on SiO{sub 2}/Si and Al{sub 2}O{sub 3} substrates.

  4. Structural improvement of zinc oxide films produced by ion beam assisted reactive sputtering

    OpenAIRE

    Köhl, D; Luysberg, M; Wuttig, M.

    2010-01-01

    Abstract Reactively sputtered Zinc Oxide thin films exhibit low crystalline order when deposited on unheated substrates. To improve the structural order, films are usually deposited onto heated substrates at temperatures of about 200-300 ?C. Nevertheless, techniques that enable room temperature deposition of ZnO films with high structural quality would be advantageous. In this work ion bombardment from an auxiliary ion gun during film growth is employed to improve the crystalline quality. ...

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

    Energy Technology Data Exchange (ETDEWEB)

    Petti, Luisa; Vogt, Christian; Büthe, Lars; Cantarella, Giuseppe; Tröster, Gerhard [Electronics Laboratory, Swiss Federal Institute of Technology, Zürich (Switzerland); Münzenrieder, Niko [Electronics Laboratory, Swiss Federal Institute of Technology, Zürich (Switzerland); Sensor Technology Research Centre, University of Sussex, Falmer (United Kingdom); Faber, Hendrik; Bottacchi, Francesca; Anthopoulos, Thomas D. [Department of Physics and Centre for Plastic Electronics, Imperial College London, London (United Kingdom)

    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

  6. Electron transport and low-temperature electrical and galvanomagnetic properties of zinc oxide and indium oxide films

    Science.gov (United States)

    Kulbachinskii, V. A.; Kytin, V. G.; Reukova, O. V.; Burova, L. I.; Kaul, A. R.; Ulyashin, A. G.

    2015-02-01

    The electrical and galvanomagnetic properties of zinc oxide films with and without gallium, aluminum, and cobalt doping and of tin-doped indium oxide films are studied over a wide range of temperatures and magnetic fields. It is shown that the mechanism for electron transport in these films changes from band to hopping transport as the degree of crystallinity of the films is reduced because of the methods and conditions for their synthesis. The change in the dimensionality of the films with band electron transport at low temperatures is studied in terms of the weak localization induced by a magnetic field. The localization radius and density of electron states in the Fermi level are estimated for the films with a hopping electron transport.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-02-01

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

  8. Metal-Oxide Film Conversions Involving Large Anions

    Energy Technology Data Exchange (ETDEWEB)

    Pretty, S.; Zhang, X.; Shoesmith, D.W.; Wren, J.C. [The University of Western Ontario, Chemistry Department, 1151 Richmond St., N6A 5B7, London, Ontario (Canada)

    2008-07-01

    The main objective of my research is to establish the mechanism and kinetics of metal-oxide film conversions involving large anions (I{sup -}, Br{sup -}, S{sup 2-}). Within a given group, the anions will provide insight on the effect of anion size on the film conversion, while comparison of Group 6 and Group 7 anions will provide insight on the effect of anion charge. This research has a range of industrial applications, for example, hazardous radioiodine can be immobilized by reaction with Ag to yield AgI. From the perspective of public safety, radioiodine is one of the most important fission products from the uranium fuel because of its large fuel inventory, high volatility, and radiological hazard. Additionally, because of its mobility, the gaseous iodine concentration is a critical parameter for safety assessment and post-accident management. A full kinetic analysis using electrochemical techniques has been performed on the conversion of Ag{sub 2}O to (1) AgI and (2) AgBr. (authors)

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

    Science.gov (United States)

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

    2017-06-01

    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 PrVO 3 thin films epitaxially on an SrTiO 3 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. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Sputtered boron indium oxide thin-film transistors

    Science.gov (United States)

    Stewart, Kevin A.; Gouliouk, Vasily; Keszler, Douglas A.; Wager, John F.

    2017-11-01

    Boron indium oxide (BIO) is studied for thin-film transistor (TFT) channel layer applications. Sputtered BIO thin films exhibit an amorphous phase over a wide range of B2O3/In2O3 ratios and remain amorphous up to 500 °C. The band gap decreases linearly with decreasing boron content, whereas device performance generally improves with decreasing boron content. The best amorphous BIO TFT exhibits a field-effect mobility of 10 cm2 V-1 s-1, turn-on voltage of 2.5 V, and sub-threshold swing of 0.72 V/dec. Decreasing the boron content to 12.5% leads to a polycrystalline phase, but further increases the mobility up to 20-40 cm2 V-1 s-1. TCAD simulation results suggest that the reason for higher performance after increasing the anneal temperature from 200 to 400 °C is due to a lower defect density in the sub-bandgap region of the BIO channel layer.

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

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Dongya; Dong, Guangneng, E-mail: donggn@mail.xjtu.edu.cn; Chen, Yinjuan; Zeng, Qunfeng

    2014-01-30

    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/dm{sup 2} 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.

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

    Science.gov (United States)

    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

  13. Preparation and characterization of CdO thin films obtained by thermal oxidation of evaporated Cd thin films

    Science.gov (United States)

    Danţuş, C.; Rusu, G. G.; Dobromir, M.; Rusu, M.

    2008-12-01

    CdO thin films ( d = 300-400 nm) were prepared by thermal oxidation of metallic Cd thin films, vacuum evaporated onto unheated glass substrates. The as-deposited Cd films were subsequently heat treated in open atmosphere in two manners: by slowly heating, with rate of 5 K/min up to the temperature of 650 K and maintained at this temperature for 5 min, and by flash heating for 5 min at the same temperature of 650 K. The effect of oxidation procedure on the crystalline structure and electrical (temperature dependence of electrical conductivity) and optical (transmission and reflection spectra) properties of as obtained CdO films was investigated. All obtained CdO films are polycrystalline with strong preferential orientation with (1 1 1) plane parallel to the substrate. Depending on the oxidation conditions, the electrical conductivity at room temperature varied in the range 5 × 10 to 5 × 10 4 Ω -1 m -1. Also, the optical band gap was found to be of 2.20-2.22 eV for direct transitions and of 1.83-1.92 eV for the indirect ones. In this paper, the obtained results are correlated with the oxidation process that takes place during film annealing.

  14. Hafnium binary alloys from experiments and first principles

    OpenAIRE

    Levy, Ohad; Hart, Gus L. W.; Curtarolo, Stefano

    2009-01-01

    Despite the increasing importance of hafnium in numerous technological applications, experimental and computational data on its binary alloys is sparse. In particular, data is scant on those binary systems believed to be phase separating. We performed a comprehensive study of 44 hafnium binary systems with alkali metals, alkaline earths, transition metals and metals, using high-throughput first principles calculations. These computations predict novel unsuspected compounds in six binary syste...

  15. Morphological Influence of Solution-Processed Zinc Oxide Films on Electrical Characteristics of Thin-Film Transistors.

    Science.gov (United States)

    Lee, Hyeonju; Zhang, Xue; Hwang, Jaeeun; Park, Jaehoon

    2016-10-19

    We report on the morphological influence of solution-processed zinc oxide (ZnO) semiconductor films on the electrical characteristics of ZnO thin-film transistors (TFTs). Different film morphologies were produced by controlling the spin-coating condition of a precursor solution, and the ZnO films were analyzed using atomic force microscopy, X-ray diffraction, X-ray photoemission spectroscopy, and Hall measurement. It is shown that ZnO TFTs have a superior performance in terms of the threshold voltage and field-effect mobility, when ZnO crystallites are more densely packed in the film. This is attributed to lower electrical resistivity and higher Hall mobility in a densely packed ZnO film. In the results of consecutive TFT operations, a positive shift in the threshold voltage occurred irrespective of the film morphology, but the morphological influence on the variation in the field-effect mobility was evident. The field-effect mobility in TFTs having a densely packed ZnO film increased continuously during consecutive TFT operations, which is in contrast to the mobility decrease observed in the less packed case. An analysis of the field-effect conductivities ascribes these results to the difference in energetic traps, which originate from structural defects in the ZnO films. Consequently, the morphological influence of solution-processed ZnO films on the TFT performance can be understood through the packing property of ZnO crystallites.

  16. Morphological Influence of Solution-Processed Zinc Oxide Films on Electrical Characteristics of Thin-Film Transistors

    Directory of Open Access Journals (Sweden)

    Hyeonju Lee

    2016-10-01

    Full Text Available We report on the morphological influence of solution-processed zinc oxide (ZnO semiconductor films on the electrical characteristics of ZnO thin-film transistors (TFTs. Different film morphologies were produced by controlling the spin-coating condition of a precursor solution, and the ZnO films were analyzed using atomic force microscopy, X-ray diffraction, X-ray photoemission spectroscopy, and Hall measurement. It is shown that ZnO TFTs have a superior performance in terms of the threshold voltage and field-effect mobility, when ZnO crystallites are more densely packed in the film. This is attributed to lower electrical resistivity and higher Hall mobility in a densely packed ZnO film. In the results of consecutive TFT operations, a positive shift in the threshold voltage occurred irrespective of the film morphology, but the morphological influence on the variation in the field-effect mobility was evident. The field-effect mobility in TFTs having a densely packed ZnO film increased continuously during consecutive TFT operations, which is in contrast to the mobility decrease observed in the less packed case. An analysis of the field-effect conductivities ascribes these results to the difference in energetic traps, which originate from structural defects in the ZnO films. Consequently, the morphological influence of solution-processed ZnO films on the TFT performance can be understood through the packing property of ZnO crystallites.

  17. RF Magnetron Sputtering Aluminum Oxide Film for Surface Passivation on Crystalline Silicon Wafers

    Directory of Open Access Journals (Sweden)

    Siming Chen

    2013-01-01

    Full Text Available Aluminum oxide films were deposited on crystalline silicon substrates by reactive RF magnetron sputtering. The influences of the deposition parameters on the surface passivation, surface damage, optical properties, and composition of the films have been investigated. It is found that proper sputtering power and uniform magnetic field reduced the surface damage from the high-energy ion bombardment to the silicon wafers during the process and consequently decreased the interface trap density, resulting in the good surface passivation; relatively high refractive index of aluminum oxide film is benefic to improve the surface passivation. The negative-charged aluminum oxide film was then successfully prepared. The surface passivation performance was further improved after postannealing by formation of an SiOx interfacial layer. It is demonstrated that the reactive sputtering is an effective technique of fabricating aluminum oxide surface passivation film for low-cost high-efficiency crystalline silicon solar cells.

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

    Science.gov (United States)

    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.

  19. Impedance investigation of thermally formed oxide films on AISI 304L stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Hamadou, L. [Laboratoire de Materiaux, Electrochimie et Corrosion, Universite Mouloud Mammeri de Tizi-Ouzou, B.P. 17, Tizi-Ouzou 15000 (Algeria)], E-mail: lamhama@yahoo.fr; Kadri, A.; Benbrahim, N. [Laboratoire de Materiaux, Electrochimie et Corrosion, Universite Mouloud Mammeri de Tizi-Ouzou, B.P. 17, Tizi-Ouzou 15000 (Algeria)

    2010-03-15

    Thin oxide layers on 304L stainless steel were grown by thermal oxidation at 300 deg. C at different durations ranging from 2 to 4 h. The structural characterization of the oxide films was carried out by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Electrochemical impedance spectroscopy was used to investigate the effects of exposure time and applied potential on the electronic properties of these films. Oxide films are described by a multilayer structure, with n-type iron oxide and oxyhydroxide in the outer layers and p-type chromium oxide in the inner layer. Doping densities evaluated from Mott-Schottky plots increased with the oxidation duration, with characteristics of highly disordered semiconductor.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Henry, Michael David; Wolfley, Steven L.; Young, Travis Ryan; Monson, Todd; Pearce, Charles Joseph; Lewis, Rupert M.; Clark, Blythe; Brunke, Lyle Brent; Missert, Nancy A.

    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. As a result, Meissner magnetic measurements confirmed the bulk oxidation not observed with simple cryogenic resistivity measurements.

  2. Charge transport in nanoparticular thin films of zinc oxide and aluminum-doped zinc oxide

    OpenAIRE

    Lenz, Thomas; Richter, Moses; Matt, Gebhard J.; Luechinger, Norman A.; Halim, Samuel C.; Heiss, Wolfgang; Brabec, Christoph J.

    2015-01-01

    In this work, we report on the electrical characterization of nanoparticular thin films of zinc oxide (ZnO) and aluminum-doped ZnO (AZO). Temperature-dependent current–voltage measurements revealed that charge transport for both, ZnO and AZO, is well described by the Poole–Frenkel model and excellent agreement between the experimental data and the theoretical predictions is demonstrated. For the first time it is shown that the nature of the charge-transport is not affected by the doping of th...

  3. Thermal oxidation of Zr–Cu–Al–Ni amorphous metal thin films

    Energy Technology Data Exchange (ETDEWEB)

    Oleksak, R.P.; Hostetler, E.B.; Flynn, B.T. [School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, OR 97331 (United States); McGlone, J.M.; Landau, N.P.; Wager, J.F. [School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, OR 97331 (United States); Stickle, W.F. [Hewlett-Packard Company, Corvallis, OR 97333 (United States); Herman, G.S., E-mail: greg.herman@oregonstate.edu [School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, OR 97331 (United States)

    2015-11-30

    The initial stages of thermal oxidation for Zr–Cu–Al–Ni amorphous metal thin films were investigated using X-ray photoelectron spectroscopy, transmission electron microscopy and energy dispersive X-ray spectroscopy. The as-deposited films had oxygen incorporated during sputter deposition, which helped to stabilize the amorphous phase. After annealing in air at 300 °C for short times (5 min) this oxygen was found to segregate to the surface or buried interface. Annealing at 300 °C for longer times leads to significant composition variation in both vertical and lateral directions, and formation of a surface oxide layer that consists primarily of Zr and Al oxides. Surface oxide formation was initially limited by back-diffusion of Cu and Ni (< 30 min), and then by outward diffusion of Zr (> 30 min). The oxidation properties are largely consistent with previous observations of Zr–Cu–Al–Ni metallic glasses, however some discrepancies were observed which could be explained by the unique sample geometry of the amorphous metal thin films. - Highlights: • Thermal oxidation of amorphous Zr–Cu–Al–Ni thin films was investigated. • Significant short-range inhomogeneities were observed in the amorphous films. • An accumulation of Cu and Ni occurs at the oxide/metal interface. • Diffusion of Zr was found to limit oxide film growth.

  4. The performance of large area optical filters using dc magnetron sputtered metal thin films in oxide-metal-oxide sandwiches

    Energy Technology Data Exchange (ETDEWEB)

    Bishop, C.A.; Howson, R.P.

    1986-04-01

    The properties of metal filters with tin oxide dielectric matching layers is reported here when they are made by planar magnetron sputtering onto a flexible polyester sheet. Comparison with theoretical predictions indicate the point at which the structural effects in the film dominate the properties obtained. Silver films give visible transmittances of approximately 80% with an infrared reflectance of 90%. The performance of gold and copper are not so good. The difference between the deposited films and the theoretical performance can be explained by changes in the packing density of the film during deposition. (A.V.)

  5. Expansion Coefficient on Oxides and Oxide Ceramics.

    Science.gov (United States)

    1986-05-01

    Classification) EXPANSION COEFFICIENTS ON OXIDES AND OXIDE CERAMICS 12 PFRSONAL AUTHOR(S) Josephine Covino 13a TYPE OF REPORT 13b TIME COVERED 114 DATE OF REPORT...drastically alter expansion properties of oxides. It has been found that fine-grained (᝺ tm) anisotropic ceramic materials, such as hafnium oxide, hafnium ...Gokhale. "Thermal Expansion of Zircon ," Jap. J. AppZ. Phys., 7 (1968), p. 1126. 34 -- ’-a.’! nw-W’W L. .WW U. .PV _ 77 NWC TP 6663 81. J. L. Amoros, M

  6. Preparation, characterization and electrocatalytic behavior of zinc oxide/zinchexacyanoferrate and ruthenium oxide hexacyanoferrate hybrid film-modified electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Chu, H.-W.; Thangamuthu, R. [Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, No. 1, Section 3, Chung-Hsiao East Road, Taipei 106, Taiwan (China); Chen, S.-M. [Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, No. 1, Section 3, Chung-Hsiao East Road, Taipei 106, Taiwan (China)], E-mail: smchen78@ms15.hinet.net

    2008-02-15

    Polynuclear mixed-valent hybrid films of zinc oxide/zinchexacyanoferrate and ruthenium oxide hexacyanoferrate (ZnO/ZnHCF-RuOHCF) have been deposited on electrode surfaces from H{sub 2}SO{sub 4} solution containing Zn(NO{sub 3}){sub 2}, RuCl{sub 3} and K{sub 3}[Fe(CN){sub 6}] by potentiodynamic cycling method. Simultaneous cyclic voltammetry and electrochemical quartz crystal microbalance (EQCM) measurements demonstrate the steady growth of hybrid film. Surface morphology of hybrid film was investigated using scanning electron microscopy (SEM). Energy dispersive spectrometer (EDS) data confirm existence of zinc oxide and ruthenium oxide hexacyanoferrate (RuOHCF) in the hybrid film. The effect of type of monovalent cations on the redox behavior of hybrid film was investigated. In pure supporting electrolyte, electrochemical responses of Ru{sup II/III} redox transition occurring at negative potential region resemble with that of a surface immobilized redox couple. The electrocatalytic activity of ZnO/ZnHCF-RuOHCF hybrid film was investigated towards oxidation of epinephrine, dopamine and L-cysteine, and reduction of S{sub 2}O{sub 8}{sup 2-} and SO{sub 5}{sup 2-} as well as IO{sub 3}{sup -} using cyclic voltammetry and rotating ring disc electrode (RRDE) techniques.

  7. Correlation between stoichiometry and properties of scandium oxide films prepared by reactive magnetron sputtering

    Science.gov (United States)

    Belosludtsev, Alexandr; Juškevičius, Kęstutis; Ceizaris, Lukas; Samuilovas, Romanas; Stanionytė, Sandra; Jasulaitienė, Vitalija; Kičas, Simonas

    2018-01-01

    Scandium oxide films were deposited on fused silica substrates by reactive pulsed DC magnetron sputtering. The use of feed-back optical emission monitoring enabled high-rate reactive deposition of films with tunable stoichiometry and properties. The under-stoichiometric, stoichiometric and over-stoichiometric scandium oxide films were prepared. The compressive stress in films was between 235 and 530 MPa. We showed that phase structure, density, surface roughness and optical properties of the scandium oxide are affected by the film stoichiometry and deposition conditions. Transparent scandium oxide films were slightly hydrophobic (94 ± 3°), homogeneous with a crystallite size of 20 ± 5 nm. The lowest extinction coefficient 0.7 × 10-3, the highest refractive index 2.08 (both quantities at the wavelength of 355 nm) and the highest density 4.1 ± 0.1 g cm-3 exhibited film prepared with the stoichiometric composition. Stoichiometric scandium oxide can be used in various optical applications as high refractive index and wide bandgap material. Transitions to under- or over-stoichiometry lead to a decrease of film density, refractive index and increase of the extinction coefficient.

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

    Directory of Open Access Journals (Sweden)

    Luke Klosterman

    2016-12-01

    Full Text Available 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.

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

    Science.gov (United States)

    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 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Tripathy, Sumanta K.; Rajeswari, V. P. [Centre for Nano Science and Technology, GVP College of Engineering (Autonomous), Visakhapatnam- 530048 (India)

    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.

  11. The structure and the gas sensitive properties of the thin films of zinc oxide

    Science.gov (United States)

    Zhilova, O. V.; Pankov, S. Yu.; Sitnikov, A. V.; Kalinin, Yu. E.; Babkina, I. V.

    2017-09-01

    The zinc oxide (ZnO) thin films were obtained by the ion-beam sputtering. It was shown that ZnO films have a hexagonal crystal structure of the space symmetry group P63mc. The film is slightly textured in the direction (0002). After the heat treatment, the crystal structure is preserved. A ZnO film with a thickness of 90 nm was annealed at a temperature of 600 °C. The relative change in the resistance of this film at a temperature of 400 °C after the addition of hydrogen to the air with a partial pressure of 5 Torr showed high values.

  12. Effect of thickness on optoelectrical properties of Mo-doped indium oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, R.K. [Department of Physics, Astronomy, and Materials Science, Missouri State University, 901 South National Avenue, Kemper Hall, Springfield, MO 65897 (United States)], E-mail: ramguptamsu@gmail.com; Ghosh, K. [Department of Physics, Astronomy, and Materials Science, Missouri State University, 901 South National Avenue, Kemper Hall, Springfield, MO 65897 (United States); Patel, R. [Roy Blunt Jordan Valley Innovation Center, Missouri State University, Springfield, MO 65806 (United States); Kahol, P.K. [Department of Physics, Astronomy, and Materials Science, Missouri State University, 901 South National Avenue, Kemper Hall, Springfield, MO 65897 (United States)

    2008-12-30

    Molybdenum-doped indium oxide films of various thicknesses were deposited on quartz substrate by pulsed laser deposition technique. The effect of thickness on structural, optical, and electrical properties was studied. X-ray diffraction studied revealed that all the films are highly oriented along (2 2 2) direction. It is observed that film crystallinity increases with thickness. These films are highly transparent (82-96%) in visible region. Atomic force microscopy analysis shows that the films are very smooth with root mean square surface roughness of 0.95 nm for 10 nm thick film. It is observed that resistivity of the films decreases from 1.05 x 10{sup -4} {omega} cm to 6.06 x 10{sup -5} {omega} cm, while mobility increases from 172 cm{sup 2}/Vs to 263 cm{sup 2}/Vs with increases in film thickness from 10 nm to 125 nm, respectively.

  13. Thickness dependence of optoelectrical properties of tungsten-doped indium oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, R.K., E-mail: ramguptamsu@gmail.com [Department of Physics, Astronomy, and Materials Science, Missouri State University, Springfield, MO 65897 (United States); Ghosh, K.; Kahol, P.K. [Department of Physics, Astronomy, and Materials Science, Missouri State University, Springfield, MO 65897 (United States)

    2009-08-15

    Pulsed laser deposition technique is used for deposition of tungsten-doped indium oxide films. The effect of film thickness on structural, optical and electrical properties was studied using X-ray diffraction (XRD), atomic force microscopy, UV-visible spectroscopy, and electrical measurements. X-ray diffraction study reveals that all the films are highly crystalline and oriented along (2 2 2) direction and the film crystallinity increases with increase in film thickness. Atomic force microscopy analysis shows that these films are very smooth with root mean square surface roughness of {approx}1.0 nm. Bandgap energy of the films depends on thickness and varies from 3.71 eV to 3.94 eV. It is observed that resistivity of the films decreases with thickness, while mobility increases.

  14. Anodic luminescence, structural, photoluminescent, and photocatalytic properties of anodic oxide films grown on niobium in phosphoric acid

    Energy Technology Data Exchange (ETDEWEB)

    Stojadinović, Stevan, E-mail: sstevan@ff.bg.ac.rs [University of Belgrade, Faculty of Physics, Studentski trg 12-16, 11000 Belgrade (Serbia); Tadić, Nenad [University of Belgrade, Faculty of Physics, Studentski trg 12-16, 11000 Belgrade (Serbia); Radić, Nenad [University of Belgrade, Institute of Chemistry, Technology and Metallurgy, Department of Catalysis and Chemical Engineering, Njegoševa 12, 11000 Belgrade (Serbia); Stefanov, Plamen [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Block 11, 1113 Sofia (Bulgaria); Grbić, Boško [University of Belgrade, Institute of Chemistry, Technology and Metallurgy, Department of Catalysis and Chemical Engineering, Njegoševa 12, 11000 Belgrade (Serbia); Vasilić, Rastko [University of Belgrade, Faculty of Physics, Studentski trg 12-16, 11000 Belgrade (Serbia)

    2015-11-15

    Graphical abstract: - Highlights: • Anodic luminescence is correlated to the existence of morphological defects in the oxide. • Spectrum under spark discharging reveals only oxygen and hydrogen lines. • Oxide films formed under spark discharging are crystallized and composed of Nb{sub 2}O{sub 5}. • Photocatalytic activity and photoluminescence of Nb{sub 2}O{sub 5} films increase with time. - Abstract: 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 Nb{sub 2}O{sub 5} 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.

  15. Inter-Diffusion of Copper and Hafnium as Studied by X-Ray Photoelectron Spectroscopy

    Science.gov (United States)

    Pearson, Justin Seth

    The purpose of this study is to investigate the interdiffusion of copper and hafnium. Thin films (thicknesses ranging from 100 nm to 150 nm) of hafnium were deposited on a silicon substrate. About 80 nm of copper was then deposited on such samples. High purity samples have been used in this investigation. The deposition of the elements was done by the e-beam technique. The interfaces thus formed were annealed for a fixed time (30 minutes) at temperatures of 100, 200, and 300°C. The samples were characterized in situ by the x-ray photoelectron spectroscopy technique. To carry out the depth profiling of these samples a controlled amount of the over layer was removed and the spectral data were acquired. The argon ion sputtering technique was used to sputter the layers away. Spectral data in the copper 2p and hafnium 4f regions were investigated. The atomic concentration of the constituents as a function of depth across the interface was determined by analyzing the areas under the curves. The depth profiling data thus obtained was analyzed by the Matano-Boltzmann's procedure. For this analysis the Matano plane was determined based on the criteria of equal area on each side of the interface. The Fick's Law second law was used to calculate the interdiffuison coefficient for each of these interfaces. The interdiffusion coefficient as a function of temperature was determined from these analyses. From these coefficients the activation energy and the pre-exponential factor was determined by using the Arrhenius plot. The activation energy was found to be 0.128 eV/atom and the pre-exponential factor was 3.33E-14 cm2/s. The results from this investigation will be useful in the application of Cu/Hf interface in design and fabrication of semiconductor devices.

  16. Oxidant-Dependent Thermoelectric Properties of Undoped ZnO Films by Atomic Layer Deposition

    KAUST Repository

    Kim, Hyunho

    2017-02-27

    Extraordinary oxidant-dependent changes in the thermoelectric properties of undoped ZnO thin films deposited by atomic layer deposition (ALD) have been observed. Specifically, deionized water and ozone oxidants are used in the growth of ZnO by ALD using diethylzinc as a zinc precursor. No substitutional atoms have been added to the ZnO films. By using ozone as an oxidant instead of water, a thermoelectric power factor (σS) of 5.76 × 10 W m K is obtained at 705 K for undoped ZnO films. In contrast, the maximum power factor for the water-based ZnO film is only 2.89 × 10 W m K at 746 K. Materials analysis results indicate that the oxygen vacancy levels in the water- and ozone-grown ZnO films are essentially the same, but the difference comes from Zn-related defects present in the ZnO films. The data suggest that the strong oxidant effect on thermoelectric performance can be explained by a mechanism involving point defect-induced differences in carrier concentration between these two oxides and a self-compensation effect in water-based ZnO due to the competitive formations of both oxygen and zinc vacancies. This strong oxidant effect on the thermoelectric properties of undoped ZnO films provides a pathway to improve the thermoelectric performance of this important material.

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

    Energy Technology Data Exchange (ETDEWEB)

    Nicholas, Jason Dale [Univ. of California, Berkeley, CA (United States)

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

    Science.gov (United States)

    2012-01-01

    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. PMID:22221518

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

    Science.gov (United States)

    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. Copyright 2010. Published by Elsevier Ltd.

  20. Vanadium oxide thin films deposited on silicon dioxide buffer layers by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Chen Sihai [Department of Optoelectronic Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China) and Wuhan National laboratory for Optoelectronics, Wuhan 430074 (China)]. E-mail: cshai99@yahoo.com; Ma Hong [Department of Electronics and Information Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Wang Shuangbao [Department of Optoelectronic Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Shen Nan [Department of Optoelectronic Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Xiao Jing [Department of Optoelectronic Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Zhou Hao [Department of Optoelectronic Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Zhao Xiaomei [Department of Optoelectronic Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Wuhan National laboratory for Optoelectronics, Wuhan 430074 (China); Li Yi [Department of Optoelectronic Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); State Key Laboratory for Imaging Recognization and Intelligence Control, Huazhong University of Science and Technology, Wuhan 430074 (China); Yi Xinjian [State Key Laboratory for Imaging Recognization and Intelligence Control, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2006-02-21

    Thin films made by vanadium oxide have been obtained by direct current magnetron sputtering method on SiO{sub 2} buffer layers. A detailed electrical and structural characterization has been performed on the deposited films by four-point probe method and scanning electron microscopy (SEM). At room temperature, the four-point probe measurement result presents the resistance of the film to be 25 kU/sheet. The temperature coefficient of resistance is - 2.0%/K. SEM image indicates that the vanadium oxide exhibits a submicrostructure with lamella size ranging from 60 nm to 300 nm. A 32 x 32-element test microbolometer was fabricated based on the deposited thin film. The infrared response testing showed that the response was 200 mV. The obtained results allow us to conclude that the vanadium oxide thin films on SiO{sub 2} buffer layers is suitable for uncooled focal plane arrays applications.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  3. Sodium alginate/graphene oxide composite films with enhanced thermal and mechanical properties.

    Science.gov (United States)

    Ionita, Mariana; Pandele, Madalina Andreea; Iovu, Horia

    2013-04-15

    Sodium alginate/graphene oxide (Al/GO) nanocomposite films with different loading levels of graphene oxide were prepared by casting from a suspension of the two components. The structure, morphologies and properties of Al/GO films were characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning (SEM) and transmission electron microscopy (TEM), thermal gravimetric (TG) analysis, and tensile tests. The results revealed that hydrogen bonding and high interfacial adhesion between GO filler and Al matrix significantly changed thermal stability and mechanical properties of the nanocomposite films. The tensile strength (σ) and Young's modulus (E) of Al films containing 6 wt% GO increased from 71 MPa and 0.85 GPa to 113 MPa and 4.18 GPa, respectively. In addition, TG analysis showed that the thermal stability of Al/GO composite films was better than that of neat Al film. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Non-hydrolytic metal oxide films for perovskite halide overcoating and stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Martinson, Alex B.; Kim, In Soo

    2017-09-26

    A method of protecting a perovskite halide film from moisture and temperature includes positioning the perovskite halide film in a chamber. The chamber is maintained at a temperature of less than 200 degrees Celsius. An organo-metal compound is inserted into the chamber. A non-hydrolytic oxygen source is subsequently inserted into the chamber. The inserting of the organo-metal compound and subsequent inserting of the non-hydrolytic oxygen source into the chamber is repeated for a predetermined number of cycles. The non-hydrolytic oxygen source and the organo-metal compound interact in the chamber to deposit a non-hydrolytic metal oxide film on perovskite halide film. The non-hydrolytic metal oxide film protects the perovskite halide film from relative humidity of greater than 35% and a temperature of greater than 150 degrees Celsius, respectively.

  5. 40 CFR 471.90 - Applicability; description of the zirconium-hafnium forming subcategory.

    Science.gov (United States)

    2010-07-01

    ... zirconium-hafnium forming subcategory. 471.90 Section 471.90 Protection of Environment ENVIRONMENTAL... POINT SOURCE CATEGORY Zirconium-Hafnium Forming Subcategory § 471.90 Applicability; description of the zirconium-hafnium forming subcategory. This subpart applies to discharges of pollutants to waters of the...

  6. 40 CFR 421.330 - Applicability: Description of the primary zirconium and hafnium subcategory.

    Science.gov (United States)

    2010-07-01

    ... primary zirconium and hafnium subcategory. 421.330 Section 421.330 Protection of Environment ENVIRONMENTAL... CATEGORY Primary Zirconium and Hafnium Subcategory § 421.330 Applicability: Description of the primary zirconium and hafnium subcategory. The provisions of this subpart are applicable to discharges resulting...

  7. Oxidized potato starch based thermoplastic films : Effect of combination of hydrophilic and amphiphilic plasticizers

    NARCIS (Netherlands)

    Niazi, Muhammad Bilal Khan; Broekhuis, Antonius A.

    Different combinations of hydrophilic (glycerol and water) and amphiphilic (isoleucine) plasticizers were studied in the production of thermoplastic starch (TPS) powders and films from oxidized potato starch. All powder samples had an irregular and shrivelled morphology. In all mixtures containing

  8. Low Temperature, High Energy Density Micro Thin Film Solid Oxide Fuel Cell Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A new type of solid oxide fuel cell based on thin film technology and ultra-thin electrolyte is being proposed to develop to realize major reductions in fuel cell...

  9. High performance In2O3 thin film transistors using chemically derived aluminum oxide dielectric

    KAUST Repository

    Nayak, Pradipta K.

    2013-07-18

    We report high performance solution-deposited indium oxide thin film transistors with field-effect mobility of 127 cm2/Vs and an Ion/Ioff ratio of 106. This excellent performance is achieved by controlling the hydroxyl group content in chemically derived aluminum oxide (AlOx) thin-film dielectrics. The AlOx films annealed in the temperature range of 250–350 °C showed higher amount of Al-OH groups compared to the films annealed at 500 °C, and correspondingly higher mobility. It is proposed that the presence of Al-OH groups at the AlOx surface facilitates unintentional Al-doping and efficient oxidation of the indium oxide channel layer, leading to improved device performance.

  10. AB-INITIO SIMULATION OF ELECTRONIC FEATURES OF HYPERFINE RARE EARTH OXIDE FILMS FOR SENSORY NANOSYSTEMS

    Directory of Open Access Journals (Sweden)

    A. V. Gulay

    2014-01-01

    Full Text Available Ab-Initio simulation of electronic features of sensoring nanomaterials based on rare earth oxides has been made by the example of yttrium oxide. The simulation method for thin films of nanometer scale consisted in the simulation of the material layer of the thickness equal to unit crystal cell size has been proposed within the VASP simulation package. The atomic bond breakdown in the crystal along one of the coordinate axes is simulated by the increase of a distance between the atomic layers along this axis up to values at which the value of free energy is stabilized. It has been found that the valence and conductivity bands are not revealed explicitly and the band gap is not formed in the hyperfine rare earth oxide film (at the film thickness close to 1 nm. In fact the hyperfine rare earth oxide film loses dielectric properties which were exhibited clear enough in continuum.

  11. Temperature dependence of Hall mobility in indium--tin oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Morris, J.E.; Ridge, M.I.; Bishop, C.A.; Howson, R.P.

    1980-03-01

    Carrier concentrations and mobilities of vacuum-prepared indium--tin oxide films have been measured to determine the effects of annealing. The apparent variation of electron mobility with temperature in these films is interpreted in terms of a grain-boundary barrier model. No grain growth was observed in the films studied; all changes in electron density and mobility may be explained by oxygen diffusion in the grain boundaries and, from them, into the grains themselves.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  14. Transparent, flexible, all-reduced graphene oxide thin film transistors.

    Science.gov (United States)

    He, Qiyuan; Wu, Shixin; Gao, Shuang; Cao, Xiehong; Yin, Zongyou; Li, Hai; Chen, Peng; Zhang, Hua

    2011-06-28

    Owing to their unique thickness-dependent electronic properties, together with perfect flexibility and transparency, graphene and its relatives make fantastic material for use in both active channel and electrodes in various electronic devices. On the other hand, the electronic sensors based on graphene show high potential in detection of both chemical and biological species with high sensitivity. In this contribution, we report the fabrication of all-reduced graphene oxide (rGO) thin film transistors by a combination of solution-processed rGO electrodes with a micropatterned rGO channel, and then study their applications in biosensing. Our all-rGO devices are cost-effective, highly reproducible, and reliable. The fabricated electronic sensor is perfectly flexible with high transparency, showing good sensitivity in detecting proteins in the physiological buffer. As a proof of concept, fibronectin as low as 0.5 nM was successfully detected, which is comparable with the previously reported protein sensors based on single-layer pristine graphene obtained from mechanical cleavage. The specific detection of avidin by using biotinylated all-rGO sensor is also successfully demonstrated.

  15. Reduction of a thin chromium oxide film on Inconel surface upon treatment with hydrogen plasma

    Energy Technology Data Exchange (ETDEWEB)

    Vesel, Alenka, E-mail: alenka.vesel@guest.arnes.si [Jozef Stefan Institute, Jamova cesta 39, 1000 Ljubljana (Slovenia); Mozetic, Miran [Jozef Stefan Institute, Jamova cesta 39, 1000 Ljubljana (Slovenia); Balat-Pichelin, Marianne [PROMES-CNRS Laboratory, 7 Rue du four solaire, 66120 Font Romeu Odeillo (France)

    2016-11-30

    Highlights: • Oxidized Inconel alloy was exposed to hydrogen at temperatures up to 1500 K. • Oxide reduction in hydrogen plasma started at approximately 1300 K. • AES depth profiling revealed complete reduction of oxides in plasma. • Oxides were not reduced, if the sample was heated just in hydrogen atmosphere. • Surface of reduced Inconel preserved the same composition as the bulk material. - Abstract: 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.

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

    Indian Academy of Sciences (India)

    Unknown

    perature corning glass substrate by flash evaporation method. Gold was deposited on the film using thermal .... Two thin film gold electrodes were also depo-. Table 1. Parameters for fabrication of indium oxide thin .... periodic heating mode of operation, both response and recovery times are long (8–10%) (Patel et al 1994).

  17. Effective post treatment for preparing highly conductive carbon nanotube/reduced graphite oxide hybrid films.

    Science.gov (United States)

    Wang, Ranran; Sun, Jing; Gao, Lian; Xu, Chaohe; Zhang, Jing; Liu, Yangqiao

    2011-03-01

    SWCNT-reduced graphite oxide hybrid films were prepared by a filtration method. An efficient post-treatment procedure was designed to reduce GO and remove dispersants simultaneously. The sheet resistance decreased significantly after treatment, by a factor of 4-13 times. Films with excellent performance (95.6%, 655 Ω per square) were obtained and had great potential applications.

  18. X-ray study of chromium oxide films epitaxially grown on MgO

    NARCIS (Netherlands)

    Du, XS; Hak, S; Rogojami, OC; Hibma, T

    2004-01-01

    Chromium oxide films grown by molecular beam epitaxy on MgO (001) substrates were characterized by x-ray diffraction (XRD) and x-ray reflectivity (XRR) measurements. The absence of random oriented peaks in the theta-2theta spectra indicated that the thin films were a single phase. Reciprocal space

  19. Gas-chromism in ultrasonic spray pyrolyzed tungsten oxide thin films

    Indian Academy of Sciences (India)

    A simple and inexpensive ultrasonic spray pyrolysis (USP) technique has been employed to deposit tungsten oxide (WO3) thin films by spraying 2.0 mM aqueous ammonium metatungstate solution onto the amorphous glass substrates kept at 250°C. The films were further annealed at 400°C for 4 h in air. X-ray diffraction ...

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

    OpenAIRE

    Predoi, Daniela; Ciobanu, Carmen Steluta; Mihaela RADU; Costache, Marieta; Dinischiotu, Anca; Gyorgy, Eniko

    2012-01-01

    Iron oxide nanoparticles were prepared by chemical co-precipitation method. The nanoparticles were mixed with dextran in distilled water. The obtained solutions were frozen in liquid nitrogen and used as targets during matrix assisted pulsed laser evaporation for the growth of hybrid, iron oxide nanoparticles-dextran thin films. Fourier Transform Infrared Spectroscopy and X-ray diffraction investigations revealed that the obtained films preserve the structure and composition of the initial, n...

  1. Study of oxidized iron thin films by non-Rutherford elastic scattering

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez-Villacorta, F. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco, 28049 Madrid (Spain)]. E-mail: felixjv@icmm.csic.es; Munoz-Martin, A. [Centro de Microanalisis de Materiales, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Prieto, C. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco, 28049 Madrid (Spain)

    2006-08-15

    Rutherford and non-Rutherford elastic scattering analyses have been performed to characterize oxidized iron thin films grown by sputtering. The oxygen depth profiles along the thickness of all the samples have been studied in order to unravel the oxidation process of these samples. The oxygen concentration along the film was related to the sample preparation parameters, resulting in a strong dependence of oxygen depth profile on the substrate temperature during deposition.

  2. Pulsed-laser-induced nanoscale island formation in thin metal-on-oxide films

    OpenAIRE

    Henley, SJ; Carey, JD; Silva, SRP

    2005-01-01

    he mechanisms controlling the nanostructuring of thin metal-on-oxide films by nanosecond pulsed excimer lasers are investigated. When permitted by the interfacial energetics, the breakup of the metal film into nanoscale islands is observed. A range of metals (Au, Ag, Mo, Ni, Ti, and Zn) with differing physical and thermodynamic properties, and differing tendencies for oxide formation, are investigated. The nature of the interfacial metal-substrate interaction, the thermal conductivity of the ...

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

    Energy Technology Data Exchange (ETDEWEB)

    Perry, D.L.; Thompson, A.C.; Russo, R.E. [Ernest Orlando Lawrence Berkeley National Lab., CA (United States)] [and others

    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.

  4. Thin film bismuth iron oxides useful for piezoelectric devices

    Science.gov (United States)

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

    2016-05-31

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

  5. Synthesis and characterization of barium iron oxide and bismuth iron oxide epitaxial films

    Science.gov (United States)

    Callender Bennett, Charlee J.

    Much interest exists in perovskite oxide materials and the potential they have in possessing two or more functional properties. In recent years, research on developing new materials with simultaneous ferromagnetic and ferroelectric behavior is the key to addressing possible challenges of new storage information applications. This work examines the fundamental properties of a perovskite oxide, namely BaFeO3, and the investigation of properties of a solid solution between BaFeO3 and BiFeO3. The growth and properties of epitaxial BaFeO3 thin films in the metastable cubic perovskite phase are examined. BaFeO3 films were grown on (012) LaAlO3 and (001) SrTiO3 single crystal substrates by pulsed-laser deposition. X-ray diffraction shows that in situ growth at temperatures between 650-850°C yields an oxygen-deficient BaFeO 2.5+x pseudo-cubic perovskite phase that is insulating and paramagnetic. Magnetization measurements on the asdeposited BaFeO3 films indicate non-ferromagnetic behavior. Annealing these films in 1 atm oxygen ambient converts the films into a pseudo-cubic BaFeO3-x phase that is ferromagnetic with a Curie temperature of 235 K. The observation of ferromagnetism with increasing oxygen content is consistent with superexchange coupling of Fe +4-O-Fe+4. The effects of anneal conditions on BaFeO3 are studied. X-ray characterization, such as reciprocal space maps, show more complex structure for as-grown BaFeO3-x epitaxial films. Epitaxial films grown at low laser energies are highly crystalline. However, they decompose after annealing. When grown at high laser energies, films exhibit complex structure which "cleans up" to a single pseudocubic or tetragonal structure upon ex situ anneal in oxygen ambient environment. Superlattices of BaFeO 3/SrTiO3 were synthesized to explore the nature of "cracking" in annealed BaFeO3, which occurs due to large change in lattice parameter. Magnetization of ex situ annealed BaFeO3-x epitaxial films were examined as a function of

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

    Science.gov (United States)

    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 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.

  7. Properties of electrochromic nickel-vanadium oxide films sputter-deposited from nonmagnetic alloy target

    Science.gov (United States)

    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).

  8. Nano-oxide thin films deposited via atomic layer deposition on microchannel plates.

    Science.gov (United States)

    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.

  9. Effects of working pressure on physical properties of tungsten-oxide thin films sputtered from oxide target

    Energy Technology Data Exchange (ETDEWEB)

    Riech, I.; Acosta, M.; Pena, J. L.; Bartolo-Perez, P. [Laboratorio de Ciencia de Materiales, Facultad de Ingenieria, Universidad Autonoma de Yucatan, A. P 150. Cordemex, Merida, Yucatan 97130 (Mexico); Departamento de Fisica Aplicada, CINVESTAV-IPN Unidad Merida, A.P. 73 Cordemex, Merida, Yucatan 97130 (Mexico)

    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.

  10. Experimental Parameter Effect on Ceramic Coating Film on LY12 Alloy by Micro-arc Oxidation

    Science.gov (United States)

    Zhao, H.; Yang, J. H.; Wang, X. H.

    2017-09-01

    Ceramic coatings were fabricated on the surface of LY12 aluminum alloy by micro-arc oxidation (MAO) method in NaSiO3-NaOH solution. Effect of experimental parameter on the MAO film was investigated. The results show that the ceramic layers formed on the surface of the alloy show different surface morphologies, and thickness of MAO film increases with the increase of voltage and oxidation time. These films contain two layers, an outer porous layer and an inner barrier layer, which consists mainly of γ-Al2O3 phase and a small amount of α-Al2O3 phase..

  11. Epitaxial thin film growth and properties of unconventional oxide superconductors. Cuprates and cobaltates

    Energy Technology Data Exchange (ETDEWEB)

    Krockenberger, Y.

    2006-07-01

    The discovery of high-temperature superconductors has strongly driven the development of suited thin film fabrication methods of complex oxides. One way is the adaptation of molecular beam epitaxy (MBE) for the growth of oxide materials. Another approach is the use of pulsed laser deposition (PLD) which has the advantage of good stoichiometry transfer from target to the substrate. Both techniques are used within this thesis. Epitaxial thin films of new materials are of course needed for future applications. In addition, the controlled synthesis of thin film matter which can be formed far away from thermal equilibrium allows for the investigation of fundamental physical materials properties. (orig.)

  12. DC and AC electroluminescence in silicon nanoparticles embedded in silicon-rich oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Morales-Sanchez, A; Aceves-Mijares, M [INAOE, Electronics Department, Apartado 51, Puebla, 72000 (Mexico); Barreto, J; DomInguez, C [Instituto de Microelectronica de Barcelona, IMB-CNM (CSIC), Barcelona (Spain); Peralvarez, M; Garrido, B [EME, Departament d' Electronica, Universitat de Barcelona, MartI i Franques 1, 08028 Barcelona (Spain); Luna-Lopez, J A, E-mail: amorales@inaoep.mx [CIDS-BUAP, Apartado 1651, Puebla, Pue, 72000 (Mexico)

    2010-02-26

    Electroluminescent properties of silicon-rich oxide (SRO) films were studied using metal oxide semiconductor-(MOS)-like devices. Thin SRO films with 4 at.% of silicon excess were deposited by low pressure chemical vapour deposition followed by a thermal annealing at 1100 deg. C. Intense continuous visible and infrared luminescence has been observed when devices are reversely and forwardly bias, respectively. After an electrical stress, the continuous electroluminescence (EL) is quenched but devices show strong field-effect EL with pulsed polarization. A model based on conductive paths-across the SRO film- has been proposed to explain the EL behaviour in these devices.

  13. Effect of annealing on pulse laser deposition grown copper oxide thin film

    Science.gov (United States)

    Mistry, Vaibhavi H.; Mistry, Bhaumik V.; Modi, B. P.; Joshi, U. S.

    2017-05-01

    Cuprous oxide (Cu2O) is a promising non-toxic and low cost semiconductor with potential applications in photovoltaic devices and sensor applications. Copper oxide thin films were prepared on glass substrate by pulse laser deposition. The effects of annealing on the structural, optical and electrical properties of copper oxide thin films were studied. The films were annealed in air for different temperature ranging from 200 to 450 °C. X-ray diffraction patterns reveals that the films as-deposited and annealed at 200 and 250 °C are of cuprite structure with composition Cu2O. Annealing at 300 °C and above converts these films to CuO phase. The atomic force microscopy results show that both the phase has nanocrystalline and particle size of the films is increasing with increase in annealing temperature. The conversion from Cu2O to CuO phase was confirmed by a shift in the optical band gap from 2.20 eV to 1.74 eV. The annealing conditions play a major role in the structural properties of copper oxide thin films.

  14. Physiochemical Characterization of Iodine (V Oxide Part II: Morphology and Crystal Structure of Particulate Films

    Directory of Open Access Journals (Sweden)

    Brian K. Little

    2015-11-01

    Full Text Available In this study, the production of particulate films of iodine (V oxides is investigated. The influence that sonication and solvation of suspended particles in various alcohol/ketone/ester solvents have on the physical structure of spin or drop cast films is examined in detail with electron microscopy, powder x-ray diffraction, and UV-visible absorption spectroscopy. Results indicate that sonicating iodine oxides in alcohol mixtures containing trace amounts of water decreases deposited particle sizes and produces a more uniform film morphology. UV-visible spectra of the pre-cast suspensions reveal that for some solvents, the iodine oxide oxidizes the solvent, producing I2 and lowering the pH of the suspension. Characterizing the crystals within the cast films reveal their composition to be primarily HI3O8, their orientations to exhibit a preferential orientation, and their growth to be primarily along the ac-plane of the crystal, enhanced at higher spin rates. Spin-coating at lower spin rates produces laminate-like particulate films versus higher density, one-piece films of stacked particles produced by drop casting. The particle morphology in these films consists of a combination of rods, plates, cubes, and rhombohedra structure.

  15. Hafnium isotope variations in oceanic basalts

    Science.gov (United States)

    Patchett, P. J.; Tatsumoto, M.

    1980-01-01

    Hafnium isotope ratios generated by the beta(-) decay of Lu-176 are investigated in volcanic rocks derived from the suboceanic mantle. Hf-176/Hf-177 and Lu/Hf ratios were determined to precisions of 0.01-0.04% and 0.5%, respectively, by routine, low-blank chemistry. The Hf-176/Hf-177 ratio is found to be positively correlated with the Nd-143/Nd-144 ratio and negatively correlated with the Sr-87/Sr-86 and Pb-206/Pb-204 ratios, and to increase southwards along the Iceland-Reykjanes ridge traverse. An approximate bulk earth Hf-176/Hf-177 ratio of 0.28295 is inferred from the bulk earth Nd-143/Nd-144 ratio, which requires a bulk earth Lu/Hf ratio of 0.25, similar to the Juvinas eucrite. Midocean ridge basalts are shown to account for 60% of the range of Hf isotope ratios, and it is suggested that Lu-Hf fractionation is decoupled from Sm-Nd and Rb-Sr fractionation in very trace-element-depleted source regions as a result of partial melting.

  16. Surface-dependent conductivity, transition type, and energy band structure in amorphous indium tin oxide films

    Science.gov (United States)

    Wang, Yaqin; Tang, Wu

    2017-12-01

    Amorphous indium tin oxide (ITO) thin films were deposited on polymethylmethacrylate and polyethyleneterephthalate substrates by radio frequency magnetron sputtering at room temperature. An interesting substrate morphology effect of ITO films on the conductivity, optical transition type and energy band structure was observed. A simplified film system model with a square potential for surface morphology was employed to explain the difference of conductivity. The energy band structures were also calculated based on the theory of amorphous semiconductor. The conclusion demonstrated the width of optical band gap, as well as the relative position of the Fermi level and mobility edge, which can easily be extended to the band structure determination of other transparent conductive films.

  17. Highly Sensitive and Fast Response Colorimetric Humidity Sensors Based on Graphene Oxides Film.

    Science.gov (United States)

    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.

  18. Electrodeposition and characterization of CdS thin films on stainless steel and tin oxide substrates

    Energy Technology Data Exchange (ETDEWEB)

    Fatas, E.; Herrasti, P.; Arjona, F.; Garcia Camarero, E.; Medina, J.A.

    1987-01-01

    In recent years, there has been considerable interest in electrodepositing CdS as thin films for use in photovoltaic, photorelectrochemical cells, selective surfaces, etc. Cadmium sulphide films are electrodeposited from dimethylsulphoxide (DMSO) and propylene carbonate (PC) on stainless steel and tin oxide substrates. The physical properties of the films grown in both solvents have been studied. The thickness, grain size and morphology of the CdS films have been examined using X-ray diffractometer patterns and scanning electron microscopy. Heat treatment in argon atmosphere improves the electrical conductivity of the samples.

  19. Opto-electronic properties of bismuth oxide films presenting different crystallographic phases

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, Celia L. [Instituto de Investigaciones en Materiales, UNAM, Circuito Exterior s/n CU, México D.F. 04510 (Mexico); Posgrado en Ciencia e Ingeniería de Materiales, UNAM, Unidad de Posgrado, Edificio C, Piso 1, Zona Cultural de CU, México, D.F. 04510 (Mexico); Depablos-Rivera, Osmary, E-mail: osmarydep@yahoo.com [Instituto de Investigaciones en Materiales, UNAM, Circuito Exterior s/n CU, México D.F. 04510 (Mexico); Posgrado en Ciencia e Ingeniería de Materiales, UNAM, Unidad de Posgrado, Edificio C, Piso 1, Zona Cultural de CU, México, D.F. 04510 (Mexico); Silva-Bermudez, Phaedra [Instituto de Investigaciones en Materiales, UNAM, Circuito Exterior s/n CU, México D.F. 04510 (Mexico); Instituto Nacional de Rehabilitación, Calz. México Xochimilco No. 289 Col. Arenal de Guadalupe, C.P.14389, Ciudad de México, D.F. (Mexico); Muhl, Stephen [Instituto de Investigaciones en Materiales, UNAM, Circuito Exterior s/n CU, México D.F. 04510 (Mexico); Zeinert, Andreas; Lejeune, Michael; Charvet, Stephane; Barroy, Pierre [Laboratoire de Physique de la Matière Condensée, Université de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens Cedex 1 (France); Camps, Enrique [Instituto Nacional de Investigaciones Nucleares, Carretera México-Toluca S/N, kilómetro 36.5. La Marquesa, Municipio de Ocoyoacac, CP 52750, Estado de México (Mexico); Rodil, Sandra E. [Instituto de Investigaciones en Materiales, UNAM, Circuito Exterior s/n CU, México D.F. 04510 (Mexico)

    2015-03-02

    The optical, electrical and structural properties of bismuth oxide thin films deposited by radio frequency reactive magnetron sputtering were studied. The Bi{sub 2}O{sub 3} thin films were grown on Si and glass substrates under different power and substrate temperatures in an oxygen-enriched plasma leading to films with different crystalline phase as evidenced by X-ray diffraction and Raman spectroscopy. The optical properties of the films were measured using ellipsometric spectroscopy and optical transmission spectra. In order to parameterize the optical dispersion functions (n, k) of the films, the Tauc–Lorentz dispersion model was used. The optical bandgap was then assessed by different methods and the results are compared to the thermal variations of the electrical resistivity of the films. It was found that the refractive index, extinction coefficient and optical gap strongly depend on the deposition conditions and the crystalline phase; the fluorite defect cubic δ-Bi{sub 2}O{sub 3} phase showed the lowest optical gap and lower resistivity. - Highlights: • Different bismuth oxide phases were obtained by sputtering. • The power and substrate temperature were the two key parameters. • Room temperature delta-Bi{sub 2}O{sub 3} thin films were obtained. • The optical bandgap was around 1.5 and 2.2 eV, depending on the phase. • The bismuth oxide films presented activation energies around 1 eV.

  20. Ellipsometric spectroscopy study of cobalt oxide thin films deposited by sol-gel

    Energy Technology Data Exchange (ETDEWEB)

    Barrera-Calva, E.; Martinez-Flores, J.C. [Departamento de Ingenieria de Procesos e Hidraulica, UAM ? Iztapalapa, Av. Rafael Atlixco No. 186, Col. Vicentina, Mexico DF 09340 (Mexico); Huerta, L. [Instituto de Investigacion en Materiales, Universidad Nacional Autonoma de Mexico, Mexico DF (Mexico); Avila, A.; Ortega-Lopez, M. [Depto. Ingenieria Electrica, SEES, CINVESTAV- IPN, Mexico DF 07360 (Mexico)

    2006-09-22

    Due to their unique optical properties, solar selective coatings enhance the thermal efficiency of solar photothermal converters. Hence it seems to be interesting to study the optical properties of promising materials as solar selective coatings. In an earlier work, it was demonstrated that sol-gel deposited cobalt oxide thin films possess suitable optical properties as selective coatings. In this work, cobalt oxide thin films were prepared by same technique and their optical properties were analyzed as a function of the dipping time of the substrate in the sol, using the spectroscopy ellipsometry, atomic force microscopy and X-ray photoelectron spectroscopy techniques. The optical constants (n and k) for these films, in the 200-800nm range, are reported as a function of the dipping time. The fitting of ellipsometric data, I{sub s} and I{sub c}, for the glass substrate and the cobalt oxide thin film, as modeled with the Lorentz and Tauc-Lorentz dispersion relations, indicated that the film microstructure resembles a multilayer stack with voids. From these results, the Co{sub 3}O{sub 4} and void percentages in the film were estimated. Both, thin film thickness and void/Co{sub 3}O{sub 4} percentage ratio, were determined to be strongly dependent on the immersion time. Furthermore, the total thickness of a multilayered film was found to be the sum of thickness of each individual layer. (author)

  1. Tungsten oxide thin films obtained by anodisation in low electrolyte concentration

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Nadja B.D. da [Centro de Ciências Químicas, Farmacêuticas e de Alimentos, Universidade Federal de Pelotas, Campus Capão do Leão, s/n, Pelotas, RS (Brazil); Pazinato, Julia C.O. [Instituto de Química, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500 Porto Alegre, RS (Brazil); Sombrio, Guilherme; Pereira, Marcelo B.; Boudinov, Henri [Instituto de Física, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500 Porto Alegre, RS (Brazil); Gündel, André; Moreira, Eduardo C. [Universidade Federal do Pampa, Travessa 45, 1650 Bagé, RS (Brazil); Garcia, Irene T.S., E-mail: irene.garcia@ufrgs.br [Instituto de Química, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500 Porto Alegre, RS (Brazil)

    2015-03-02

    Tungsten oxide nanostructured films were grown on tungsten substrates by anodisation under a fixed voltage and with sodium fluoride as electrolyte. The effect of the anion chloride and the influence of the modifying agent disodium hydrogen phosphate in the tungsten oxide films were also investigated. The structural characterisation of the films was performed by scanning electron microscopy, atomic force microscopy and Raman spectroscopy. The band gap was determined through diffuse reflectance spectroscopy. The thin films were photoluminescent and emitted in the range of 300 to 630 nm when irradiated at 266 nm. The synthesised films efficiently degraded of methyl orange dye in the presence of hydrogen peroxide and 250 nm radiation. The modifying agent was responsible for the improvement of the photocatalytic activity. Films with similar photocatalytic performance were obtained when the system sodium fluoride and disodium hydrogen phosphate were replaced by sodium chloride. The porous structure and low band gap values were responsible for the photocatalytic behaviour. - Highlights: • Tungsten oxide thin films were obtained by anodisation of tungsten in aqueous media. • The performance of the NaCl, NaF and NaF/Na{sub 2}HPO{sub 4} as electrolytes was investigated. • The relation between structure and optical behaviour has been discussed. • Films obtained with NaCl and NaF/Na{sub 2}HPO{sub 4} present similar photocatalytic activity.

  2. Stabilization of ultrathin (hydroxy)oxide films on transition metal substrates for electrochemical energy conversion

    Science.gov (United States)

    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.

  3. Semiconducting properties of oxide films formed onto an Nb electrode in NaOH solutions

    Directory of Open Access Journals (Sweden)

    VLADIMIR D. JOVIC

    2008-03-01

    Full Text Available In this paper, the results of the potentiostatic formation of homogeneous and heterogeneous, nano-crystalline passive films of Nb2O5 onto an Nb electrode in NaOH solutions of different concentrations at potentials lower than 3.0 V vs. SCE are presented. The semiconducting properties of such films were investigated by EIS measurements. After fitting the EIS results by appropriate equivalent circuits, the space charge capacitance (Csc and space charge resistance (Rsc of these films were determined. The donor density (Nsc, flat band potential (Efb and thickness of the space charge layer (dsc for such oxide films were determined from the corresponding Mott–Schottky (M–S plots. It is shown that all oxide films were n-type semiconductors in a certain potential range.

  4. Graphene oxide on magnetron sputtered silver thin films for SERS and metamaterial applications

    Science.gov (United States)

    Politano, Grazia Giuseppina; Cazzanelli, Enzo; Versace, Carlo; Vena, Carlo; De Santo, Maria Penelope; Castriota, Marco; Ciuchi, Federica; Bartolino, Roberto

    2018-01-01

    In the last years the potential of combining the attractive materials characteristics of graphene related materials and silver nanostructures for SERS and metamaterials has emerged. Here, we report of graphene oxide thin films deposited by dip-coating on magnetron sputtered silver thin films. Our work represents a novelty in the field of the study of graphene oxide- silver composites, since magnetron sputtering deposition is an alternative way to silver thin films fabrication; previous works used instead silver nitrate aqueous solution mixed with the graphene oxide. Micro-Raman technique, morphological analysis and variable angle spectroscopic ellipsometry were performed. The final SERS signal intensity was investigated and we found Raman peaks dependent on the intensity of the laser and the thickness of silver and GO films. These results could open somestudies on plasmonics and on the reduction of graphene oxide mediated by silver thin films. Moreover, effective medium theory calculations show the possible use of these graphene oxide/silver thin films in multilayer hyperbolic metamaterials for optical applications.

  5. Gas-Phase Deposition of Ultrathin Aluminium Oxide Films on Nanoparticles at Ambient Conditions

    NARCIS (Netherlands)

    Valdesueiro Gonzalez, D.; Meesters, G.M.H.; Kreutzer, M.T.; Van Ommen, J.R.

    2015-01-01

    We have deposited aluminium oxide films by atomic layer deposition on titanium oxide nanoparticles in a fluidized bed reactor at 27 ± 3 °C and atmospheric pressure. Working at room temperature allows coating heat-sensitive materials, while working at atmospheric pressure would simplify the scale-up

  6. Thin film zinc oxide gas sensor fabricated using near-field electrospray

    National Research Council Canada - National Science Library

    Zheng, Gaofeng; Zhu, Ping; Sun, Lingling; Jiang, Jiaxin; Liu, Juan; Wang, Xiang; Li, Wenwang

    2016-01-01

    .... These particles were heated and oxidized to form a zinc oxide (ZnO) semiconductor at 500 °C. The resulting ZnO thin film on the comb electrode was incorporated into a gas sensor, which was examined using a custom built measurement system...

  7. Difference in charge transport properties of Ni-Nb thin films with native and artificial oxide

    Energy Technology Data Exchange (ETDEWEB)

    Trifonov, A. S., E-mail: trifonov.artem@phys.msu.ru [Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, 1(2), Leninskie Gory, GSP-1, Moscow 119991 (Russian Federation); Physics Faculty, Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Lubenchenko, A. V. [Department of General Physics and Nuclear Fusion, National Research University ' Moscow Power Engineering Institute,' Moscow 111250 (Russian Federation); Polkin, V. I. [National University of Science and Technology “MISiS,” Moscow 119049 (Russian Federation); Pavolotsky, A. B. [Chalmers University of Technology, Göteborg 41296 (Sweden); Ketov, S. V.; Louzguine-Luzgin, D. V. [WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)

    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.

  8. Self-assembly of a thin highly reduced graphene oxide film and its high electrocatalytic activity.

    Science.gov (United States)

    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.

  9. Morphology control of zinc oxide films via polysaccharide-mediated, low temperature, chemical bath deposition

    Directory of Open Access Journals (Sweden)

    Florian Waltz

    2015-03-01

    Full Text Available 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.

  10. Morphology control of zinc oxide films via polysaccharide-mediated, low temperature, chemical bath deposition.

    Science.gov (United States)

    Waltz, Florian; Schwarz, Hans-Christoph; Schneider, Andreas M; Eiden, Stefanie; Behrens, Peter

    2015-01-01

    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.

  11. The growth and evolution of thin oxide films on delta-plutonium surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Flores, Harry G [Los Alamos National Laboratory; Pugmire, David L [Los Alamos National Laboratory

    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.

  12. Effects of Thermal Annealing on the Optical Properties of Titanium Oxide Thin Films Prepared by Chemical Bath Deposition Technique

    OpenAIRE

    H.U. Igwe; O.E. Ekpe; E.I. Ugwu

    2010-01-01

    A titanium oxide thin film was prepared by chemical bath deposition technique, deposited on glass substrates using TiO2 and NaOH solution with triethanolamine (TEA) as the complexing agent. The films w ere subjected to post deposition annealing under various temperatures, 100, 150, 200, 300 and 399ºC. The thermal treatment streamlined the properties of the oxide films. The films are transparent in the entire regions of the electromagnetic spectrum, firmly adhered to the substrate and resistan...

  13. Transparent conductive zinc oxide basics and applications in thin film solar cells

    CERN Document Server

    Klein, Andreas; Rech, Bernd

    2008-01-01

    Zinc oxide (ZnO) belongs to the class of transparent conducting oxides which can be used as transparent electrodes in electronic devices or heated windows. In this book the material properties of, the deposition technologies for, and applications of zinc oxide in thin film solar cells are described in a comprehensive manner. Structural, morphological, optical and electronic properties of ZnO are treated in this review. The editors and authors of this book are specialists in deposition, analysis and fabrication of thin-film solar cells and especially of ZnO. This book is intended as an overview and a data collection for students, engineers and scientist.

  14. A review on the recent developments of solution processes for oxide thin film transistors

    Science.gov (United States)

    Du Ahn, Byung; Jeon, Hye-Ji; Sheng, Jiazhen; Park, Jozeph; Park, Jin-Seong

    2015-06-01

    This review article introduces the recent advances in the development of oxide semiconductor materials based on solution processes and their potential applications. In the early stage, thin film transistors based on oxide semiconductors fabricated by solution processes used to face critical problems such as high annealing temperatures (>400 °C) required to obtain reasonable film quality, and the relatively low field effect mobility (biosensors, and non-volatile memory devices. As such, further innovations in the solution process methods of oxide semiconductor devices are anticipated to allow the realization of cost effective, large area electronics in the near future.

  15. Laser-Scribed Photo-thermal Reduction of Graphene-Oxide for Thin Film Sensor Applications

    OpenAIRE

    Kazemzadeh, Rouzbeh

    2015-01-01

    In this thesis, a cost effective, simple and fast method of reduction of Graphene Oxide thin film is proposed. Graphene oxide is a non-conductive material intrinsically and one of the techniques to convert it to conductive material is using laser beam to remove oxygen groups from its surface, in other words, to reduce it. Laser parameters must be optimized for an effective and successful reduction. Thin film of non-conductive Graphene oxide is converted into conductive thin layer by fast lase...

  16. The effect of hydrogen peroxide on uranium oxide films on 316L stainless steel

    Science.gov (United States)

    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.

  17. Epitaxial oxide thin films by pulsed laser deposition: Retrospect and ...

    Indian Academy of Sciences (India)

    Unknown

    Among the large number of processes to fabricate thin films of materials, pulsed laser deposition (PLD) has emerged as a ... It is important to recognize that highly stoichiometric, nearly single crystal like epitaxial film is aimed for in the PLD .... This new class of Josephson junctions is attractive for novel phase devices.

  18. Oriented growth of thin films of samarium oxide by MOCVD

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Thin films of Sm2O3 have been grown on Si(100) and fused quartz by low-pressure chemical va- pour deposition using an adducted β-diketonate precursor. The films on quartz are cubic, with no preferred orientation at lower growth temperatures (~ 550°C), while they grow with a strong (111) orientation as the.

  19. Pulsed laser deposition of transparent conductive oxide thin films on flexible substrates

    Science.gov (United States)

    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.

  20. The formation of tin oxides in thin-film Sn/C/KCl(100) structures

    Energy Technology Data Exchange (ETDEWEB)

    Yurakov, Yu. A., E-mail: ftt@phys.vsu.ru; Ryabtsev, S. V.; Chuvenkova, O. A.; Domashevskaya, E. P.; Nikitenko, A. S. [Voronezh State University (Russian Federation); Kannykin, S. V.; Kushchev, S. B., E-mail: kusheev@phis.vorstu.ru [Voronezh State Technical University (Russian Federation)

    2009-01-15

    The formation of oxides upon the thermal annealing (both in air and vacuum) of island tin films grown on a KCl(100) substrate, which was coated by a thin layer of amorphous carbon, has been investigated by transmission electron microscopy. It is established that thermal annealing at temperatures below the tin melting point (T{sub m}) does not lead to phase transitions with the formation of new crystalline oxide phases. At the same time, the films undergo structural changes: the average size of blocks in the substrate plane decreases compared to those in an as-deposited film. Thermal annealing in air at temperatures above the tin melting point leads to the formation of multiphase oxide structures and increases the average size of blocks and islands in the substrate plane. It is shown that preliminary thermal annealing in air at temperatures below T{sub m} hinders oxidation upon subsequent heat treatment.

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

    Energy Technology Data Exchange (ETDEWEB)

    Letti, C.J. [Universidade de Brasilia, Instituto de Fisica, 70910-000 Brasilia, DF (Brazil); Paterno, L.G. [Universidade de Brasilia, Instituto de Quimica, 70910-000 Brasilia, DF (Brazil); Pereira-da-Silva, M.A. [Instituto de Fisica de São Carlos, USP, 13560-9700 São Carlos, SP (Brazil); Centro Universitario Central Paulista – UNICEP, 13563-470 São Carlos, SP (Brazil); Morais, P.C. [Universidade de Brasilia, Instituto de Fisica, 70910-000 Brasilia, DF (Brazil); Soler, M.A.G., E-mail: soler@unb.br [Universidade de Brasilia, Instituto de Fisica, 70910-000 Brasilia, DF (Brazil)

    2017-02-15

    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, Fe{sub 3}O{sub 4}-np are synthesized by the co-precipitation method and assembled layer-by-layer with sodium sulfonated polystyrene (PSS). Polymer films (Fe{sub 3}O{sub 4}-np/PSS){sub 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 Fe{sub 3}O{sub 4}-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 Fe{sub 3}O{sub 4}-np is intensified in films with more bilayers, since more water is included in those films. Encapsulation of Fe{sub 3}O{sub 4}-np by PSS in layer-by-layer films showed to be very efficient to avoid the oxidation process in nanosized magnetite. - Graphical abstract: Encapsulation of Fe{sub 3}O{sub 4}-np by PSS in layer-by-layer films avoids the oxidation and phase transformation of nanosized magnetite. - Highlights: • (Fe{sub 3}O{sub 4}-np/PSS){sub n} nanofilms, with n=2 up to 25, where layer-by-layer assembled. • The influence of film architecture on the Fe{sub 3}O{sub 4}-np oxidation was investigated through Raman spectroscopy. • Encapsulation of Fe{sub 3}O{sub 4}-np by PSS showed to be very efficient to avoid the Fe{sub 3}O{sub 4}-np oxidation.

  2. Electrical and optical properties of indium zinc oxide (IZO) thin films by continuous composition spread.

    Science.gov (United States)

    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.

  3. Characterization of Semolina Protein Film with Incorporated Zinc Oxide Nano Rod Intended for Food Packaging

    Directory of Open Access Journals (Sweden)

    Jafarzadeh Shima

    2017-09-01

    Full Text Available This study intended to provide biopolymer films used as food packaging, which will result in reducing environmental pollution produced by the activities of synthetic food packaging. We used zinc oxide nanorods (ZnO-nr and we prepared nanocomposite films by means of solvent casting. FTIR and SEM were employed to characterize the final films. SEM images revealed that ZnO-nr particles were homogenously distributed throughout the film surface. The thermal, optical, and heat sealability properties of the films were also examined. Adding ZnO-nr significantly reduced oxygen permeability and heat sealability. The semolina films’ UV absorbance was highly impacted by the degree of ZnO-nr addition. The nanocomposite films absorbed above 90% of the near infrared spectra. In addition, the zeta potential revealed the surface charge of ZnO-nr had a negative charge of about −33.9 mV.

  4. Crystal orientation dependent thermoelectric properties of highly oriented aluminum-doped zinc oxide thin films

    KAUST Repository

    Abutaha, Anas I.

    2013-02-06

    We demonstrate that the thermoelectric properties of highly oriented Al-doped zinc oxide (AZO) thin films can be improved by controlling their crystal orientation. The crystal orientation of the AZO films was changed by changing the temperature of the laser deposition process on LaAlO3 (100) substrates. The change in surface termination of the LaAlO3 substrate with temperature induces a change in AZO film orientation. The anisotropic nature of electrical conductivity and Seebeck coefficient of the AZO films showed a favored thermoelectric performance in c-axis oriented films. These films gave the highest power factor of 0.26 W m−1 K−1 at 740 K.

  5. Nickel oxide thin film from electrodeposited nickel sulfide thin film: peroxide sensing and photo-decomposition of phenol.

    Science.gov (United States)

    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.

  6. Optical, structural and electrochromic properties of sputter- deposited W-Mo oxide thin films

    Science.gov (United States)

    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.

  7. Protecting BOPP film from UV degradation with an atomic layer deposited titanium oxide surface coating

    Energy Technology Data Exchange (ETDEWEB)

    Lahtinen, Kimmo, E-mail: kimmo.lahtinen@lut.fi [ASTRaL, Lappeenranta University of Technology, Mikkeli (Finland); Maydannik, Philipp; Seppänen, Tarja; Cameron, David C. [ASTRaL, Lappeenranta University of Technology, Mikkeli (Finland); Johansson, Petri; Kotkamo, Sami; Kuusipalo, Jurkka [Paper Converting and Packaging Technology, Tampere University of Technology, Tampere (Finland)

    2013-10-01

    Titanium oxide layers were deposited onto a BOPP film by atomic layer deposition in order to prevent UV degradation of the film. The coatings were deposited in a low-temperature process at 80 °C by using tetrakis(dimethylamido)titanium and ozone as titanium and oxygen precursors, respectively. UV block characteristics of the coatings and their effect on the polymer were measured by using UV–vis and IR spectrometry, and differential scanning calorimetry. According to the results, the coatings provided a considerable decrease in the photodegradation of the BOPP film during UV exposure. IR spectra showed that during a 6-week UV exposure, a 67 nm titanium oxide coating was able to almost completely prevent the formation of photodegradation products in the film. The mechanical properties of the film were also protected by the coating, but as opposed to what the IR study suggested they were still somewhat compromised by the UV light. After a 6-week exposure, the tensile strength and elongation at break of the 67 nm titanium oxide coated film decreased to half of the values measured before the treatment. This should be compared to the complete degradation suffered by the uncoated base sheet already after only 4 weeks of treatment. The results show that nanometre scale inorganic films deposited by ALD show a promising performance as effective UV protection for BOPP substrates.

  8. High performance of symmetrical supercapacitor based on multilayer films of graphene oxide/polypyrrole electrodes

    Energy Technology Data Exchange (ETDEWEB)

    De la Fuente Salas, Ixra Marisol [Department of Chemical Engineering, Technological Institute of La Laguna, Torreón, Coahuila (Mexico); Sudhakar, Y.N. [Department of Chemistry, Manipal Institute of Technology, Manipal, Karnataka (India); Selvakumar, M., E-mail: chemselva78@gmail.com [Department of Chemistry, Manipal Institute of Technology, Manipal, Karnataka (India)

    2014-03-01

    Graphical abstract: Schematic representation of synthesis of graphene oxide/PPy multilayer film. - Highlights: • Influence of current density, concentration of supporting electrolyte and conducting polymer deposition time on GO matrix are studied in detail. • High performance capacitive electrode for multilayer film of GO/PPy is compared with single layer GO/PPy film. • Morphology of the multilayer film and probable mechanism of multilayer deposition of PPy in GO are discussed. - Abstract: In this work we have deposited multlilayer films of polypyrrole (PPy) by galvanostatic method with three different dopants namely p-toluenesulphonic acid, benzene sulphonic acid, and sulfuric acid ions on graphene oxide (GO) layer. The better deposition of PPy films on GO is addressed by studying the influence of different electrolytes, concentrations and current densities. The multilayer films of GO/PPy exhibits greater capacitance compared to GO/PPy single layer. The morphology of the graphene oxide (GO)/multilayer nano PPy structures is carefully analyzed by scanning electron microscopy, FTIR and XPS spectrum. Specific capacitance of fabricated supercapacitor using multilayer electrodes is as high as 332 F g{sup −1} at 10 mV s{sup −1} and also compared with another supercapacitor made from single GO/PPy layer whose capacitance is 215 F g{sup −1}. Galvanostatic charge–discharge studies show good performance and stability.

  9. Chemical resistance of thin film materials based on metal oxides grown by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Sammelselg, Väino, E-mail: vaino.sammelselg@ut.ee [Institute of Physics, University of Tartu, Riia 142, 51014 Tartu (Estonia); Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu (Estonia); Netšipailo, Ivan; Aidla, Aleks; Tarre, Aivar; Aarik, Lauri; Asari, Jelena; Ritslaid, Peeter; Aarik, Jaan [Institute of Physics, University of Tartu, Riia 142, 51014 Tartu (Estonia)

    2013-09-02

    Etching rate of technologically important metal oxide thin films in hot sulphuric acid was investigated. The films of Al-, Ti-, Cr-, and Ta-oxides studied were grown by atomic layer deposition (ALD) method on silicon substrates from different precursors in large ranges of growth temperatures (80–900 °C) in order to reveal process parameters that allow deposition of coatings with higher chemical resistance. The results obtained demonstrate that application of processes that yield films with lower concentration of residual impurities as well as crystallization of films in thermal ALD processes leads to significant decrease of etching rate. Crystalline films of materials studied showed etching rates down to values of < 5 pm/s. - Highlights: • Etching of atomic layer deposited thin metal oxide films in hot H{sub 2}SO{sub 4} was studied. • Smallest etching rates of < 5 pm/s for TiO{sub 2}, Al{sub 2}O{sub 3}, and Cr{sub 2}O{sub 3} were reached. • Highest etching rate of 2.8 nm/s for Al{sub 2}O{sub 3} was occurred. • Remarkable differences in etching of non- and crystalline films were observed.

  10. Preparation of bioactive titania films on titanium metal via anodic oxidation.

    Science.gov (United States)

    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.

  11. Fabrication of Au/graphene oxide/Ag sandwich structure thin film and its tunable energetics and tailorable optical properties

    Directory of Open Access Journals (Sweden)

    Ruijin Hong

    2017-01-01

    Full Text Available Au/graphene oxide/Ag sandwich structure thin film was fabricated. The effects of graphene oxide (GO and bimetal on the structure and optical properties of metal silver films were investigated by X-ray diffraction (XRD, optical absorption, and Raman intensity measurements, respectively. Compared to silver thin film, Au/graphene oxide/Ag sandwich structure composite thin films were observed with wider optical absorption peak and enhanced absorption intensity. The Raman signal for Rhodamine B molecules based on the Au/graphene oxide/Ag sandwich nanostructure substrate were obviously enhanced due to the bimetal layer and GO layer with tunable absorption intensity and fluorescence quenching effects.

  12. Restorative effect of oxygen annealing on device performance in HfIZO thin-film transistors

    Directory of Open Access Journals (Sweden)

    Tae-Jun Ha

    2015-03-01

    Full Text Available Metal-oxide based thin-film transistors (oxide-TFTs are very promising for use in next generation electronics such as transparent displays requiring high switching and driving performance. In this study, we demonstrate an optimized process to secure excellent device performance with a favorable shift of the threshold voltage toward 0V in amorphous hafnium-indium-zinc-oxide (a-HfIZO TFTs by using post-treatment with oxygen annealing. This enhancement results from the improved interfacial characteristics between gate dielectric and semiconductor layers due to the reduction in the density of interfacial states related to oxygen vacancies afforded by oxygen annealing. The device statistics confirm the improvement in the device-to-device and run-to-run uniformity. We also report on the photo-induced stability in such oxide-TFTs against long-term UV irradiation, which is significant for transparent displays.

  13. Annealing induced structural evolution and electrochromic properties of nanostructured tungsten oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Ching-Lin [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan, ROC (China); Lin, Chung-Kwei [School of Dental Technology, Taipei Medical University, Taipei City 110, Taiwan, ROC (China); Wang, Chun-Kai [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan, ROC (China); Wang, Sheng-Chang [Department of Mechanical Engineering, Southern Taiwan University, Tainan 710, Taiwan, ROC (China); Huang, Jow-Lay, E-mail: JLH888@mail.ncku.edu.tw [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan, ROC (China); Department of Chemical and Materials Engineering, National University of Kaohsiung, Kaohsiung 81148, Taiwan, ROC (China); Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan 701, Taiwan, ROC (China)

    2013-12-31

    The effect of microstructure on the optical and electrochemical properties of nanostructured tungsten oxide films was evaluated as a function of annealing temperature. The films using block copolymer as the template were prepared from peroxotungstic acid (PTA) by spin-coating onto the substrate and post-annealed at 250–400 °C to form tungsten oxide films with nanostructure. The microstructure of the films was measured by X-ray diffraction and surface electron microscopy. The films annealed at temperatures below 300 °C are characterized by amorphous or nanocrystalline structures with a pore size of less than 10 nm. The evaluated annealing temperature caused a triclinic crystalline structure and microcracks. Cyclic voltammetry measurements were performed in a LiClO{sub 4}-propylene carbonate electrolyte. The results showed that the ion inserted capacity were maximized for films annealed at 300 °C and decreased with the increasing of annealing temperature. The electrochromic properties of the nanostructured tungsten oxide films were evaluated simultaneously by potentiostat and UV–vis spectroscopy. The films annealed at 300 °C exhibit high transmission modulation (∆T ∼ 40%) at λ = 633 nm and good kinetic properties. As a result, the correlation between the microstructure and kinetic properties was established, and the electrochromic properties have been demonstrated. - Highlights: • Surfactant-assisted WO{sub 3} films have been prepared by sol–gel method. • Nanostructure of porous WO{sub 3} film is retained after crystallization. • Kinetic properties of WO{sub 3} can be improved by nanostructure and crystallinity.

  14. Low-Concentration Indium Doping in Solution-Processed Zinc Oxide Films for Thin-Film Transistors.

    Science.gov (United States)

    Zhang, Xue; Lee, Hyeonju; Kwon, Jung-Hyok; Kim, Eui-Jik; Park, Jaehoon

    2017-07-31

    We investigated the influence of low-concentration indium (In) doping on the chemical and structural properties of solution-processed zinc oxide (ZnO) films and the electrical characteristics of bottom-gate/top-contact In-doped ZnO thin-film transistors (TFTs). The thermogravimetry and differential scanning calorimetry analysis results showed that thermal annealing at 400 °C for 40 min produces In-doped ZnO films. As the In content of ZnO films was increased from 1% to 9%, the metal-oxygen bonding increased from 5.56% to 71.33%, while the metal-hydroxyl bonding decreased from 72.03% to 9.63%. The X-ray diffraction peaks and field-emission scanning microscope images of the ZnO films with different In concentrations revealed a better crystalline quality and reduced grain size of the solution-processed ZnO thin films. The thickness of the In-doped ZnO films also increased when the In content was increased up to 5%; however, the thickness decreased on further increasing the In content. The field-effect mobility and on/off current ratio of In-doped ZnO TFTs were notably affected by any change in the In concentration. Considering the overall TFT performance, the optimal In doping concentration in the solution-processed ZnO semiconductor was determined to be 5% in this study. These results suggest that low-concentration In incorporation is crucial for modulating the morphological characteristics of solution-processed ZnO thin films and the TFT performance.

  15. Low-Concentration Indium Doping in Solution-Processed Zinc Oxide Films for Thin-Film Transistors

    Directory of Open Access Journals (Sweden)

    Xue Zhang

    2017-07-01

    Full Text Available We investigated the influence of low-concentration indium (In doping on the chemical and structural properties of solution-processed zinc oxide (ZnO films and the electrical characteristics of bottom-gate/top-contact In-doped ZnO thin-film transistors (TFTs. The thermogravimetry and differential scanning calorimetry analysis results showed that thermal annealing at 400 °C for 40 min produces In-doped ZnO films. As the In content of ZnO films was increased from 1% to 9%, the metal-oxygen bonding increased from 5.56% to 71.33%, while the metal-hydroxyl bonding decreased from 72.03% to 9.63%. The X-ray diffraction peaks and field-emission scanning microscope images of the ZnO films with different In concentrations revealed a better crystalline quality and reduced grain size of the solution-processed ZnO thin films. The thickness of the In-doped ZnO films also increased when the In content was increased up to 5%; however, the thickness decreased on further increasing the In content. The field-effect mobility and on/off current ratio of In-doped ZnO TFTs were notably affected by any change in the In concentration. Considering the overall TFT performance, the optimal In doping concentration in the solution-processed ZnO semiconductor was determined to be 5% in this study. These results suggest that low-concentration In incorporation is crucial for modulating the morphological characteristics of solution-processed ZnO thin films and the TFT performance.

  16. Picosecond laser registration of interference pattern by oxidation of thin Cr films

    Energy Technology Data Exchange (ETDEWEB)

    Veiko, Vadim; Yarchuk, Michail [ITMO University, Kronverksky Ave. 49, St. Petersburg, 197101 (Russian Federation); Zakoldaev, Roman, E-mail: zakoldaev@gmail.com [ITMO University, Kronverksky Ave. 49, St. Petersburg, 197101 (Russian Federation); Gedvilas, Mindaugas; Račiukaitis, Gediminas [Center for Physical Sciences and Technology, Savanoriu Ave. 231, LT-02300, Vilnius (Lithuania); Kuzivanov, Michail; Baranov, Alexander [ITMO University, Kronverksky Ave. 49, St. Petersburg, 197101 (Russian Federation)

    2017-05-15

    Highlights: • Periodical patterning of thin films was achieved by combining two technologies. • Selective chemical etching was combined with laser-induced oxidation. • Formation of the protective oxide layer prevented of chromium film from etching. • 1D binary grating with the chromium stripe width of 750 nm was fabricated. - Abstract: The laser oxidation of thin metallic films followed by its selective chemical etching is a promising method for the formation of binary metal structures on the glass substrates. It is important to confirm that even a single ultrashort laser pulse irradiation is able to create the protective oxide layer that makes possible to imprint the thermochemical image. Results of the thermo-chemical treatment of thin chromium films irradiated by picosecond laser pulse utilizing two and four beam interference combined with the chemical etching are presented. The spatial resolution of this method can be high enough due to thermo-chemical sharpening and can be close to the diffraction limit. Micro-Raman spectroscopy was applied for characterization of the chemical composition of the protective oxide layers formed under atmospheric conditions on the surface of thin chromium films.

  17. Preparation and spectroscopic analysis of zinc oxide nanorod thin films of different thicknesses

    Directory of Open Access Journals (Sweden)

    Mia Nasrul Haque

    2017-10-01

    Full Text Available Zinc oxide thin films with different thicknesses were prepared on microscopic glass slides by sol-gel spin coating method, then hydrothermal process was applied to produce zinc oxide nanorod arrays. The nanorod thin films were characterized by various spectroscopic methods of analysis. From the images of field emission scanning electron microscope (FESEM, it was observed that for the film thickness up to 200 nm the formed nanorods with wurtzite hexagonal structure were uniformly distributed over the entire surface substrate. From X-ray diffraction analysis it was revealed that the thin films had good polycrystalline nature with highly preferred c-axis orientation along (0 0 2 plane. The optical characterization done by UV-Vis spectrometer showed that all the films had high transparency of 83 % to 96 % in the visible region and sharp cut off at ultraviolet region of electromagnetic spectrum. The band gap of the films decreased as their thickness increased. Energy dispersive X-ray spectroscopy (EDS showed the presence of zinc and oxygen elements in the films and Fourier transform infrared spectroscopy (FT-IR revealed the chemical composition of ZnO in the film.

  18. Zinc-oxide nanorod/copper-oxide thin-film heterojunction for a nitrogen-monoxide gas sensor

    Science.gov (United States)

    Yoo, Hwansu; Kim, Hyojin; Kim, Dojin

    2014-11-01

    A novel p- n oxide heterojunction structure was fabricated by employing n-type zinc-oxide (ZnO) nanorods grown on an indium-tin-oxide-coated glass substrate by using the hydrothermal method and a p-type copper-oxide (CuO) thin film deposited onto the ZnO nanorod array by using the sputtering method. The crystallinities and microstructures of the heterojunction materials were examined by using X-ray diffraction and scanning electron microscopy. The observed current-voltage characteristics of the p - n oxide heterojunction showed a nonlinear diode-like rectifying behavior. The effects of an oxidizing or electron acceptor gas, such as nitrogen monoxide (NO), on the ZnO nanorod/CuO thin-film heterojunction were investigated to determine the potential applications of the fabricated material for use in gas sensors. The forward current of the p - n heterojunction was remarkably reduced when NO gas was introduced into dry air at temperatures from 100 to 250 °C. The NO gas response of the oxide heterojunction reached a maximum value at an operating temperature of 180 °C and linearly increased as the NO gas concentration was increased from 5 to 30 ppm. The sensitivity value was observed to be as high as 170% at 180 °C when biased at 2 V in the presence of 20-ppm NO. The ZnO nanorod/CuO thin-film heterojunction also exhibited a stable and repeatable response to NO gas. The experimental results suggest that the ZnO nanorod/CuO thin-film heterojunction structure may be a novel candidate for gas sensors.

  19. Zinc-oxide nanorod / copper-oxide thin-film heterojunction for a nitrogen-monoxide gas sensor

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Hwansu; Kim, Hyojin; Kim, Dojin [Chungnam National University, Daejeon (Korea, Republic of)

    2014-11-15

    A novel p - n oxide heterojunction structure was fabricated by employing n-type zinc-oxide (ZnO) nanorods grown on an indium-tin-oxide-coated glass substrate by using the hydrothermal method and a p-type copper-oxide (CuO) thin film deposited onto the ZnO nanorod array by using the sputtering method. The crystallinities and microstructures of the heterojunction materials were examined by using X-ray diffraction and scanning electron microscopy. The observed current - voltage characteristics of the p - n oxide heterojunction showed a nonlinear diode-like rectifying behavior. The effects of an oxidizing or electron acceptor gas, such as nitrogen monoxide (NO), on the ZnO nanorod/CuO thin-film heterojunction were investigated to determine the potential applications of the fabricated material for use in gas sensors. The forward current of the p - n heterojunction was remarkably reduced when NO gas was introduced into dry air at temperatures from 100 to 250 .deg. C. The NO gas response of the oxide heterojunction reached a maximum value at an operating temperature of 180 .deg. C and linearly increased as the NO gas concentration was increased from 5 to 30 ppm. The sensitivity value was observed to be as high as 170% at 180 .deg. C when biased at 2 V in the presence of 20-ppm NO. The ZnO nanorod/CuO thin-film heterojunction also exhibited a stable and repeatable response to NO gas. The experimental results suggest that the ZnO nanorod/CuO thin-film heterojunction structure may be a novel candidate for gas sensors.

  20. Tin etching from metallic and oxidized scandium thin films

    NARCIS (Netherlands)

    Pachecka, Malgorzata; Lee, Christopher James; Sturm, J.M.; Bijkerk, Frederik

    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

  1. Annealing effects on the structural and optical properties of vanadium oxide film obtained by the hot-filament metal oxide deposition technique (HFMOD)

    Energy Technology Data Exchange (ETDEWEB)

    Scarminio, Jair; Silva, Paulo Rogerio Catarini da, E-mail: scarmini@uel.br, E-mail: prcsilva@uel.br [Universidade Estadual de Londrina (UEL), PR (Brazil). Departamento de Fisica; Gelamo, Rogerio Valentim, E-mail: rogelamo@gmail.com [Universidade Federal do Triangulo Mineiro (UFTM), Uberaba, MG (Brazil); Moraes, Mario Antonio Bica de, E-mail: bmoraes@mailhost.ifi.unicamp.br [Universidade Estadual de Campinas (UNICAMP), SP (Brazil)

    2017-01-15

    Vanadium oxide films amorphous, nonstoichiometric and highly absorbing in the optical region were deposited on ITO-coated glass and on silicon substrates, by the hot-filament metal oxide deposition technique (HFMOD) and oxidized by ex-situ annealing in a furnace at 200, 300, 400 and 500 deg C, under an atmosphere of argon and rarefied oxygen. X-ray diffraction, Raman and Rutherford backscattering spectroscopy as well as optical transmission were employed to characterize the amorphous and annealed films. When annealed at 200 and 300 deg C the as-deposited opaque films become transparent but still amorphous. Under treatments at 400 and 500 deg C a crystalline nonstoichiometric V{sub 2}O{sub 5} structure is formed. All the annealed films became semiconducting, with their optical absorption coefficients changing with the annealing temperature. An optical gap of 2.25 eV was measured for the films annealed at 400 and 500 deg C. The annealing in rarefied oxygen atmosphere proved to be a useful and simple ex-situ method to modulate the structural and optical properties of vanadium oxide films deposited by HFMOD technique. This technique could be applied to other amorphous and non-absorbing oxide films, replacing the conventional and sometimes expensive method of modulate desirable film properties by controlling the film deposition parameters. Even more, the HFMOD technique can be an inexpensive alternative to deposit metal oxide films. (author)

  2. Preparation and properties of transparent conducting zinc oxide and aluminium-doped zinc oxide films prepared by evaporating method

    Energy Technology Data Exchange (ETDEWEB)

    Ma, J.; Ji, F.; Ma, H.I.; Li, S.Y. [Institute of Optoelectronic Materials and Devices, Shandong University, Jinan (China)

    2000-02-01

    Undoped and aluminium-doped zinc oxide films have been prepared by thermal evaporation of zinc acetate [Zn(CH{sub 3}COO){sub 2} 2H{sub 2}O] and aluminium chloride [AlCl{sub 3}] onto a heated glass substrate. The structural and optoelectrical properties of the films have been studied. The effects of heat treatment for the as-deposited films in air and vaccum are investigated. Highly transparent films with conductivity as low as 2x10{sup -3}{omega}cm can be produced by controlling the deposition parameters. The electron carrier densities are in the range 0.2-7x10{sup 19}cm{sup -3} with mobilities of 22-58cm{sup 2}V{sup -1}s{sup -1}.

  3. Discovery of Gallium, Germanium, Lutetium, and Hafnium Isotopes

    CERN Document Server

    Gross, J L

    2011-01-01

    Currently, twenty-eight gallium, thirty-one germanium, thirty-five lutetium, and thirty-six hafnium isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

  4. Elastic and thermodynamic properties of zirconium-and hafnium ...

    Indian Academy of Sciences (India)

    ... Live Streaming. Home; Journals; Bulletin of Materials Science; Volume 41; Issue 1. Elastic and thermodynamic properties of zirconium- and hafnium-doped Rh 3 V intermetallic compounds: potential aerospace material. M MANJULA M SUNDARESWARI E VISWANATHAN. Volume 41 Issue 1 February 2018 Article ID 19 ...

  5. Elastic and thermodynamic properties of zirconium- and hafnium ...

    Indian Academy of Sciences (India)

    2018-02-02

    Feb 2, 2018 ... https://doi.org/10.1007/s12034-017-1537-3. Elastic and thermodynamic properties of zirconium- and hafnium-doped Rh3V intermetallic compounds: potential aerospace material. M MANJULA, M SUNDARESWARI. ∗ and E VISWANATHAN. Department of Physics, Sathyabama University, Chennai 600119, ...

  6. Low-temperature atomic layer deposition of copper(II) oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Iivonen, Tomi, E-mail: tomi.iivonen@helsinki.fi; Hämäläinen, Jani; Mattinen, Miika; Popov, Georgi; Leskelä, Markku [Laboratory of Inorganic Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki (Finland); Marchand, Benoît; Mizohata, Kenichiro [Division of Materials Physics, Department of Physics, University of Helsinki, P.O. Box 43, FI-00014 Helsinki (Finland); Kim, Jiyeon; Fischer, Roland A. [Chair of Inorganic Chemistry II, Ruhr-University Bochum, Universitätsstrasse 150, 44780 Bochum (Germany)

    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. Characteristics of Thermally Reduced Graphene Oxide Thin Film as DSSC Counter Electrode

    Science.gov (United States)

    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%.

  8. Tuning electrical properties in amorphous zinc tin oxide thin films for solution processed electronics.

    Science.gov (United States)

    Chandra, R Devi; Rao, Manohar; Zhang, Keke; Prabhakar, Rajiv Ramanujam; Shi, Chen; Zhang, Jie; Mhaisalkar, Subodh G; Mathews, Nripan

    2014-01-22

    Solution processed zinc tin oxide (ZTO) thin film transistors (TFTs) were fabricated by varying the Zn/Sn composition. The addition of Sn to the zinc oxide (ZnO) films resulted in improved electrical characteristics, with devices of Zn0.7Sn0.3O composition showing the highest mobility of 7.7 cm(2)/(V s). An improvement in subthreshold swings was also observed, indicative of a reduction of the interfacial trap densities. Mobility studies at low temperature have been carried out, which indicated that the activation energy was reduced with Sn incorporation. Kelvin probe force microscopy was performed on the films to evaluate work function and correlated to the metal-semiconductor barrier indicating Zn0.7Sn0.3O films had the smallest barrier for charge injection. Organic-inorganic hybrid complementary inverters with a maximum gain of 10 were fabricated by integrating ZTO TFTs with poly-3-hexylthiophene (P3HT) transistors.

  9. CEMS spectra of non-spherical nanoparticles in oxidized iron thin films

    Energy Technology Data Exchange (ETDEWEB)

    Rubin, J., E-mail: jrubin@unizar.es [CSIC-Universidad de Zaragoza, Instituto de Ciencia de Materiales de Aragon (Spain); Jimenez-Villacorta, F. [Campus de Cantoblanco, Instituto de Ciencia de Materiales de Madrid, CSIC (Spain); Bartolome, J. [CSIC-Universidad de Zaragoza, Instituto de Ciencia de Materiales de Aragon (Spain); Prieto, C. [Campus de Cantoblanco, Instituto de Ciencia de Materiales de Madrid, CSIC (Spain)

    2008-07-15

    Room temperature CEMS spectra and field-cooled and zero field-cooled hysteresis loops have been measured on oxidized iron films of 100 nm thickness. The iron films were sputtered on a Si substrate, while the substrate temperature, T{sub s}, was kept at 200 K and 300 K, and subsequently oxidized. The magnetization of the T{sub s} = 200 K sample decreases ca. 40% with respect to the T{sub s} = 300 K one, and a small exchange bias appears. The CEMS spectra show a preferential orientation of the magnetization of the films, which is more tilted toward a direction parallel to the film plane as T{sub s} is decreased, which is attributed to a competition between shape anisotropies.

  10. Highly stable thin film transistors using multilayer channel structure

    KAUST Repository

    Nayak, Pradipta K.

    2015-03-09

    We report highly stable gate-bias stress performance of thin film transistors (TFTs) using zinc oxide (ZnO)/hafnium oxide (HfO2) multilayer structure as the channel layer. Positive and negative gate-bias stress stability of the TFTs was measured at room temperature and at 60°C. A tremendous improvement in gate-bias stress stability was obtained in case of the TFT with multiple layers of ZnO embedded between HfO2 layers compared to the TFT with a single layer of ZnO as the semiconductor. The ultra-thin HfO2 layers act as passivation layers, which prevent the adsorption of oxygen and water molecules in the ZnO layer and hence significantly improve the gate-bias stress stability of ZnO TFTs.

  11. Tin etching from metallic and oxidized scandium thin films

    Science.gov (United States)

    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.

  12. Tin etching from metallic and oxidized scandium thin films

    Directory of Open Access Journals (Sweden)

    M. Pachecka

    2017-08-01

    Full Text Available 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.

  13. Conduction and Reactivity in Heterogeneous-Molecular Catalysis: New Insights in Water Oxidation Catalysis by Phosphate Cobalt Oxide Films.

    Science.gov (United States)

    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.

  14. Performance and Stress Analysis of Metal Oxide Films for CMOS-Integrated Gas Sensors

    Directory of Open Access Journals (Sweden)

    Lado Filipovic

    2015-03-01

    Full Text Available 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.

  15. Performance and Stress Analysis of Metal Oxide Films for CMOS-Integrated Gas Sensors

    Science.gov (United States)

    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

  16. Hot-filament metal oxide deposition (HFMOD: a novel method for depositing thin films of metallic oxides

    Directory of Open Access Journals (Sweden)

    Rouxinol F. Paulo

    2004-01-01

    Full Text Available This short report describes a novel method for the synthesis of metal oxide thin films. The experimental setup consists of a metal filament installed inside a vacuum chamber. The filament can be heated by an ac power supply while oxygen is admitted into the chamber using a mass flowmeter. From reactions between oxygen and the heated metal filament, volatile oxide species, Me xOy, where Me is the metal, can be formed, condensing on a nearby substrate. We have observed that thin films of WxOy and Mo xOy can be satisfactorily deposited by this novel method. Although several techniques were used to characterize the oxides, this note emphasizes the results obtained by X-ray Photoelectron Spectroscopy (XPS.

  17. Stable solar-driven oxidation of water by semiconducting photoanodes protected by transparent catalytic nickel oxide films

    KAUST Repository

    Sun, Ke

    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. 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). © 2015, National Academy of Sciences. All rights reserved.

  18. Preparation and activation of micro-arc oxidation films on a TLM titanium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yu, S; Yu, Z T [Northwest Institute for Non-Ferrous Metal Research, Xi' an, 710016 (China)], E-mail: yusen_1982@163.com

    2008-12-15

    In order to improve the biocompatibility and surface activity of a TLM alloy, a layer of a porous TiO{sub 2} film was prepared by the micro-arc oxidation method on the surface, and then the NH{sup -}{sub 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.

  19. Preparation, structure and optical properties of transparent conducting gallium-doped zinc oxide thin films

    Directory of Open Access Journals (Sweden)

    Gu J. H.

    2015-09-01

    Full Text Available Highly conductive gallium-doped zinc oxide (GZO transparent thin films were deposited on glass substrates by RF mag­netron sputtering. The deposited films were characterized by X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, four-point probe and UV-Vis spectrophotometer, respectively. The effect of growth temperature on the structure and optoelectrical properties of the films was investigated. The results demonstrate that high quality GZO films oriented with their crystal­lographic c-axis perpendicular to the substrates are obtained. The structure and optoelectrical properties of the films are highly dependent on the growth temperature. It is found that with increasing growth temperature, the average visible transmittance of the deposited films is enhanced and the residual stress in the thin films is obviously relaxed. The GZO films deposited at the growth temperature of 400°C, which have the largest grain size (74.3 nm, the lowest electrical resistivity (1.31×10-3 Ω·cm and the maximum figure of merit (1.46×1O-2Ω-1, exhibit the best optoelectrical properties. Furthermore, the optical proper­ties of the deposited films were determined by the optical characterization methods and the optical energy-gaps were evaluated by extrapolation method. A blue shift of the optical energy gap is observed with an increase in the growth temperature.

  20. Properties of Co-deposited indium tin oxide and zinc oxide films using a bipolar pulse power supply and a dual magnetron sputter source

    Science.gov (United States)

    Hwang, Man-Soo; Seob Jeong, Heui; Kim, Won Mok; Seo, Yong Woon

    2003-07-01

    Multilayer coatings consisting of metal layers sandwiched between transparent conducting oxide layers are widely used for flat panel display electrodes and electromagnetic shield coatings for plasma displays, due to their high electrical conductivity and light transmittance. The electrical and optical properties of these multilayer films depend largely on the surface characteristics of the transparent conducting oxide thin films. A smoother surface on the transparent conducting oxide thin films makes it easier for the metal layer to form a continuous film, thus resulting in a higher conductivity and visible light transmittance. Indium tin oxide (ITO) and zinc oxide (ZnO) films were co-deposited using a dual magnetron sputter and a bipolar pulse power supply to decrease the surface roughness of the transparent conducting oxide films. The symmetric pulse mode of the power supply was used to simultaneously sputter an In2O3 (90 wt %) : SnO2 (10 wt %) target and a ZnO target. We varied the duty of the pulses to control the ratio of ITO : ZnO in the thin films. The electrical and optical properties of the films were studied, and special attention was paid to the surface roughness and the crystallinity of the films. By co-depositing ITO and ZnO at a pulse duty ratio of ITO:ZnO=45:45 using a dual magnetron sputter and a bipolar pulse power supply, we were able to obtain amorphous transparent conducting oxide films with a very smooth surface which had a Zn-rich buffer layer under a In-rich surface layer. All of the films exhibited typical electrical and optical properties of transparent conducting oxide films deposited at room temperature.

  1. High quality amorphous indium zinc oxide thin films synthesized by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Socol, G., E-mail: gabriel.socol@inflpr.ro [National Institute for Lasers, Plasma and Radiation Physics, Magurele, Ilfov (Romania); Craciun, D.; Mihailescu, I.N.; Stefan, N. [National Institute for Lasers, Plasma and Radiation Physics, Magurele, Ilfov (Romania); Besleaga, C.; Ion, L.; Antohe, S. [University of Bucharest, Faculty of Physics, 405 Atomistilor Str, POB MG-11, Magurele Ilfov 077125 (Romania); Kim, K.W.; Norton, D.; Pearton, S.J. [Materials Science and Engineering, University of Florida, Gainesville (United States); Galca, A.C. [National Institute for Materials Physics, Magurele, Ilfov (Romania); Craciun, V. [National Institute for Lasers, Plasma and Radiation Physics, Magurele, Ilfov (Romania); Materials Science and Engineering, University of Florida, Gainesville (United States)

    2011-12-01

    Indium zinc oxide films were grown from targets with two different In atomic concentration [In/(In + Zn)] of 40% and 80% by the pulsed laser deposition technique on glass substrates from room temperature up to 100 Degree-Sign C. X-ray diffraction and reflectometry investigations showed that films were amorphous and dense. Thin films (thickness < 100 nm) exhibited higher optical transmittance and resistivities than thick films (thickness > 1000 nm), probably caused by a significant decrease of oxygen vacancies due to atmosphere exposure. Films deposited from the In rich target under an oxygen pressure of 1 Pa exhibited optical transmittance higher than 85%, resistivities around 5- 7 Multiplication-Sign 10{sup -4} {Omega} cm and mobilities in the 47-54 cm{sup 2}/V s range.

  2. Indium-Doped Zinc Oxide Thin Films as Effective Anodes of Organic Photovoltaic Devices

    Directory of Open Access Journals (Sweden)

    Ziyang Hu

    2011-01-01

    Full Text Available Indium-doped zinc oxide (IZO thin films were prepared by low-cost ultrasonic spray pyrolysis (USP. Both a low resistivity (3.13×10−3 Ω cm and an average direct transmittance (400∼1500 nm about 80% of the IZO films were achieved. The IZO films were investigated as anodes in bulk-heterojunction organic photovoltaic (OPV devices based on poly(3-hexylthiophene and [6,6]-phenyl C61-butyric acid methyl ester. The device fabricated on IZO film-coated glass substrate showed an open circuit voltage of 0.56 V, a short circuit current of 8.49 mA cm-2, a fill factor of 0.40, and a power conversion efficiency of 1.91%, demonstrating that the IZO films prepared by USP technique are promising low In content and transparent electrode candidates of low-cost OPV devices.

  3. Structural improvement of zinc oxide films produced by ion beam assisted reactive sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Koehl, D; Wuttig, M [I. Institute of Physics (IA), RWTH Aachen University, D-52056 Aachen (Germany); Luysberg, M, E-mail: wuttig@physik.rwth-aachen.d [Ernst Ruska-Zentrum fuer Mikroskopie und Spektroskopie mit Elektronen/IFF, Forschungszentrum Juelich, D-52425 Juelich (Germany)

    2010-05-26

    Reactively sputtered zinc oxide thin films exhibit low crystalline order when deposited on unheated substrates. To improve the structural order, films are usually deposited onto heated substrates at temperatures of about 200-300 {sup 0}C. Nevertheless, techniques that enable room temperature deposition of ZnO films with high structural quality would be advantageous. In this work ion bombardment from an auxiliary ion gun during film growth is employed to improve the crystalline quality. Xe{sup +} ion bombardment under appropriate conditions leads to the growth of films with high crystalline order. Based on our structural investigations employing x-ray diffraction, atomic force microscopy and transmission electron microscopy, a growth model is proposed which explains the impact of ion bombardment on the structural evolution. We prove that it is especially the nucleation stage of the growth process which is susceptible to this ion bombardment.

  4. Electrical, Optical, and Thermal Behaviors of Transparent Film Heater Made of Reduced Graphene Oxide.

    Science.gov (United States)

    Kim, Ji Eun; Yoon, Kwan Han; Son, Young Gon; Park, Chul Ho; Lee, Young Sil

    2016-02-01

    The electrical conductivity and the thermal performance of the films made of reduced graphene oxide (rGO) spray-coated on polycarbonate substrate were investigated. The electrical conductivity and the transmittance of 10 times spray coated film made from the solution with 0.08 wt% of rGO, 0.16 wt% of surfactant were 30 komega/sq and 64%, respectively. The steady-state temperature of the films increased from 25 degrees C for 40 komega/sq to 100 degrees C for 490 omega/sq at an applied voltage of 110 V. The heat transfer coefficient of the rGO coated film, a, was obtained as 139 W/m2 K using the model equation based on the thermal balance, which includes Joule heating convectional, and radiative heat transfers. The transmittance of the films decreased continuously from 73% with the increase of surface resistivity.

  5. Optical and Structural Properties of Thermally Evaporated Zinc Oxide Thin Films on Polyethylene Terephthalate Substrates

    Directory of Open Access Journals (Sweden)

    M. G. Faraj

    2011-01-01

    Full Text Available Zinc oxide thin films of different thicknesses ranging from 100 to 300 nm were prepared on polyethylene terephthalate substrates with thermal evaporation in a vacuum of approximately 3×10-5 Torr. X-ray diffraction patterns confirm the proper phase formation of the material. From atomic force microscopy (AFM images, it was found that the root mean square roughness of the film surface increased as the film thickness increased. The optical properties of ZnO on PET substrates were determined through the optical transmission method using an ultraviolet-visible spectrophotometer. The optical band gap values of ZnO thin films slightly decreased as the film thickness increased.

  6. Formation of copper oxide films on fiberglass by adsorption and reaction of cuprous ions

    Energy Technology Data Exchange (ETDEWEB)

    Medina-Valtierra, Jorge; Calixto, Sergio; Ruiz, Facundo

    2004-07-22

    We have used chemical deposition of copper complex solution to prepare CuO thin films on commercial fiberglass. The deposition of copper oxides was done in a beaker using a solution of thiosulfatocuprate (I) as precursor and NaOH as a film conditioner. In order to establish a correlation between experimental conditions and the produced copper species, as well as the film quality, the as deposited and annealed samples were characterized using X-ray diffraction, visible spectrophotometry and atomic force microscopy. The most important result is that a Cu{sub 2}O 80-nm film can be obtained directly with a short immersion of fiberglass into the copper solution. The film growth of this copper phase occurred in [111] and [200] directions. Moreover, this phase is converted to CuO by annealing at 375 deg. C.

  7. Translation Effects in Fluorine Doped Tin Oxide Thin Film Properties by Atmospheric Pressure Chemical Vapour Deposition

    Directory of Open Access Journals (Sweden)

    Mohammad Afzaal

    2016-10-01

    Full Text Available In this work, the impact of translation rates in fluorine doped tin oxide (FTO thin films using atmospheric pressure chemical vapour deposition (APCVD were studied. We demonstrated that by adjusting the translation speeds of the susceptor, the growth rates of the FTO films varied and hence many of the film properties were modified. X-ray powder diffraction showed an increased preferred orientation along the (200 plane at higher translation rates, although with no actual change in the particle sizes. A reduction in dopant level resulted in decreased particle sizes and a much greater degree of (200 preferred orientation. For low dopant concentration levels, atomic force microscope (AFM studies showed a reduction in roughness (and lower optical haze with increased translation rate and decreased growth rates. Electrical measurements concluded that the resistivity, carrier concentration, and mobility of films were dependent on the level of fluorine dopant, the translation rate and hence the growth rates of the deposited films.

  8. Low-Temperature Deposition of Zinc Oxide Film by Plasma-Assisted Mist Chemical Vapor Deposition

    Science.gov (United States)

    Takenaka, Kosuke; Okumura, Yusuke; Setsuhara, Yuichi

    2012-08-01

    Zinc oxide (ZnO) film deposition using a plasma-assisted mist chemical vapor deposition (CVD) with an inductively-coupled plasma source has been performed and the effects of the plasma exposure on film properties have been investigated with oxygen mixture ratio as a parameter. With increasing oxygen mixture ratio to Ar+O2(10%), the X-ray diffraction (XRD) results showed evident peaks of ZnO(0002), indicating that highly c-axis-oriented films were grown at low substrate temperatures below 200 °C. The deposition rate of ZnO films was as high as 100 nm/min. ZnO films with an optical transmittance of 75% for the visible region and a band gap energy of 3.32 eV have been obtained by using plasma-assisted mist CVD.

  9. Plasma-Assisted Mist Chemical Vapor Deposition of Zinc Oxide Films Using Solution of Zinc Acetate

    Science.gov (United States)

    Takenaka, Kosuke; Okumura, Yusuke; Setsuhara, Yuichi

    2013-01-01

    Zinc oxide (ZnO) film deposition has been carried out by plasma-assisted mist chemical vapor deposition (CVD) using a solution of zinc acetate [Zn(CH3COO)2], and the effects of plasma exposure on film properties have been investigated in terms of RF power. With increasing RF power, the results of the X-ray diffraction (XRD) patterns of ZnO films with plasma exposure showed the existence of crystallized ZnO films with plasma exposure. Under this condition, the substrate temperature was as low as 200 °C for a plasma exposure time of 20 min. The surface morphology shown by scanning electron microscopy (SEM) images shows that the ZnO films were textured with round grains, which is attributed to the effect of the use of mist with the precursor.

  10. Synthesis and properties of iridescent Zn-containing anodic aluminum oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Xiaoxuan; Sun, Huiyuan, E-mail: huiyuansun@126.com; Liu, Lihu; Hou, Xue; Liu, Huiyuan

    2015-07-01

    A simple method of fabricating Zn-containing anodic aluminum oxide films for multifunctional anticounterfeit technology is reported. The resulting membranes were characterized with UV–vis illumination studies, natural light illumination color experiments, and electron microscopy analysis. Deposition of Zn in the nanopore region can enhance the color saturation of the thin alumina film with different colors dramatically. Both the anodization time and etching time have great influence on the structural color. The mechanisms for the emergence of this phenomenon are discussed and theoretical analysis further demonstrates the experimental results. - Highlights: • Iridescent PAA@Zn nanocomposite films were successfully fabricated. • A simple organics-assisted method is applied to making a series of fancy and multicolor patterns. • The color varies with the angle of incidence of the light used to view the film as is expected with Bragg–Snell formula. • Such colored films could be used in multifunctional anti-counterfeiting applications.

  11. Thermochemical hydrogen generation of indium oxide thin films

    Directory of Open Access Journals (Sweden)

    Taekyung Lim

    2017-03-01

    Full Text Available Development of alternative energy resources is an urgent requirement to alleviate current energy constraints. As such, hydrogen gas is gaining attention as a future alternative energy source to address existing issues related to limited energy resources and air pollution. In this study, hydrogen generation by a thermochemical water-splitting process using two types of In2O3 thin films was investigated. The two In2O3 thin films prepared by chemical vapor deposition (CVD and sputtering deposition systems contained different numbers of oxygen vacancies, which were directly related to hydrogen generation. The as-grown In2O3 thin film prepared by CVD generated a large amount of hydrogen because of its abundant oxygen vacancies, while that prepared by sputtering had few oxygen vacancies, resulting in low hydrogen generation. Increasing the temperature of the In2O3 thin film in the reaction chamber caused an increase in hydrogen generation. The oxygen-vacancy-rich In2O3 thin film is expected to provide a highly effective production of hydrogen as a sustainable and efficient energy source.

  12. Pulsed laser deposition of transparent conductive oxide thin films on flexible substrates

    Energy Technology Data Exchange (ETDEWEB)

    Socol, G., E-mail: gabriel.socol@inflpr.ro [National Institute for Lasers, Plasma and Radiation Physics, Magurele, Ilfov (Romania); Socol, M. [National Institute for Materials Physics, Magurele, Ilfov (Romania); Stefan, N.; Axente, E.; Popescu-Pelin, G.; Craciun, D.; Duta, L.; Mihailescu, C.N.; Mihailescu, I.N. [National Institute for Lasers, Plasma and Radiation Physics, Magurele, Ilfov (Romania); Stanculescu, A. [National Institute for Materials Physics, Magurele, Ilfov (Romania); Visan, D.; Sava, V. [University of Bucharest, Faculty of Physics, 405 Atomistilor Str., Magurele, Ilfov (Romania); Galca, A.C. [National Institute for Materials Physics, Magurele, Ilfov (Romania); Luculescu, C.R. [National Institute for Lasers, Plasma and Radiation Physics, Magurele, Ilfov (Romania); Craciun, V. [National Institute for Lasers, Plasma and Radiation Physics, Magurele, Ilfov (Romania); Major Analytical Instrumentation Center, University of Florida, Gainesville (United States)

    2012-11-01

    Highlights: Black-Right-Pointing-Pointer TCO thin films were grown by PLD on PET substrate at low temperature. Black-Right-Pointing-Pointer We found that the quality of TCO on PET substrate depends on the target-substrate distance. Black-Right-Pointing-Pointer TCO with high transparency (>95%) and reduced electrical resistivity ({approx}5 Multiplication-Sign 10{sup -4} {Omega} cm) were obtained. Black-Right-Pointing-Pointer Optimized TCO films deposited on PET were free of any cracks. - Abstract: 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 Multiplication-Sign 10{sup -4} {Omega} 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.

  13. Effect of oxygen deficiency on electronic properties and local structure of amorphous tantalum oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Denny, Yus Rama [Department of Physics Education, University of Sultan Ageng Tirtayasa, Banten 42435 (Indonesia); Firmansyah, Teguh [Department of Electrical Engineering, University of Sultan Ageng Tirtayasa, Banten 42435 (Indonesia); Oh, Suhk Kun [Department of Physics, Chungbuk National University, Cheongju 28644 (Korea, Republic of); Kang, Hee Jae, E-mail: hjkang@cbu.ac.kr [Department of Physics, Chungbuk National University, Cheongju 28644 (Korea, Republic of); Yang, Dong-Seok [Department of Physics Education, Chungbuk National University, Cheongju 28644 (Korea, Republic of); Heo, Sung; Chung, JaeGwan; Lee, Jae Cheol [Analytical Engineering Center, Samsung Advanced Institute of Technology, Suwon 16678 (Korea, Republic of)

    2016-10-15

    Highlights: • The effect of oxygen flow rate on electronic properties and local structure of tantalum oxide thin films was studied. • The oxygen deficiency induced the nonstoichiometric state a-TaOx. • A small peak at 1.97 eV above the valence band side appeared on nonstoichiometric Ta{sub 2}O{sub 5} thin films. • The oxygen flow rate can change the local electronic structure of tantalum oxide thin films. - Abstract: The dependence of electronic properties and local structure of tantalum oxide thin film on oxygen deficiency have been investigated by means of X-ray photoelectron spectroscopy (XPS), Reflection Electron Energy Loss Spectroscopy (REELS), and X-ray absorption spectroscopy (XAS). The XPS results showed that the oxygen flow rate change results in the appearance of features in the Ta 4f at the binding energies of 23.2 eV, 24.4 eV, 25.8, and 27.3 eV whose peaks are attributed to Ta{sup 1+}, Ta{sup 2+}, Ta{sup 3+}/Ta{sup 4+}, and Ta{sup 5+}, respectively. The presence of nonstoichiometric state from tantalum oxide (TaOx) thin films could be generated by the oxygen vacancies. In addition, XAS spectra manifested both the increase of coordination number of the first Ta-O shell and a considerable reduction of the Ta-O bond distance with the decrease of oxygen deficiency.

  14. Properties of Silver Nanowire/Zinc Oxide Transparent Bilayer Thin Films for Optoelectronic Applications.

    Science.gov (United States)

    You, Sslimsearom; Park, Yong Seo; Choi, Hyung Wook; Kim, Kyung Hwan

    2015-11-01

    We have investigated electrical, optical and structural properties of silver nanowire (AgNW)/zinc oxide (ZnO) transparent conductive bilayer films for optoelectronic applications. The AgNW/ZnO transparent conductive bilayer films were fabricated using spin-coating and facing target sputtering (FTS) method. The spin-coated the AgNW layer has advantages, such as low resistivity and high transmittance in visible range. However, the spin-coated AgNW layers can be oxidized by natural oxygen. Consequently, the conductivity of AgNW layer was strongly decreased. So, an oxidation prevented layer is necessary. The ZnO thin film layer on the Ag NW layer can be prevented oxidation. In addition, the peeling of spin-coated AgNW layer were prevented the deposited ZnO thin film layer. As the results, the sheet resistance and average transmittance in visible range of AgNW/ZnO transparent bilayer thin films exhibited 34.1 ohm/sq. and 83.46%.

  15. Chemically derived graphene oxide: towards large-area thin-film electronics and optoelectronics.

    Science.gov (United States)

    Eda, Goki; Chhowalla, Manish

    2010-06-11

    Chemically derived graphene oxide (GO) possesses a unique set of properties arising from oxygen functional groups that are introduced during chemical exfoliation of graphite. Large-area thin-film deposition of GO, enabled by its solubility in a variety of solvents, offers a route towards GO-based thin-film electronics and optoelectronics. The electrical and optical properties of GO are strongly dependent on its chemical and atomic structure and are tunable over a wide range via chemical engineering. In this Review, the fundamental structure and properties of GO-based thin films are discussed in relation to their potential applications in electronics and optoelectronics.

  16. Aligned carbon nanotube, graphene and graphite oxide thin films via substrate-directed rapid interfacial deposition.

    Science.gov (United States)

    D'Arcy, Julio M; Tran, Henry D; Stieg, Adam Z; Gimzewski, James K; Kaner, Richard B

    2012-05-21

    A procedure for depositing thin films of carbon nanostructures is described that overcomes the limitations typically associated with solution based methods. Transparent and conductively continuous carbon coatings can be grown on virtually any type of substrate within seconds. Interfacial surface tension gradients result in directional fluid flow and film spreading at the water/oil interface. Transparent films of carbon nanostructures are produced including aligned ropes of single-walled carbon nanotubes and assemblies of single sheets of chemically converted graphene and graphite oxide. Process scale-up, layer-by-layer deposition, and a simple method for coating non-activated hydrophobic surfaces are demonstrated.

  17. Roll-to-Roll Transfer Printing of Reduced Graphene Oxide Thin Film

    OpenAIRE

    Jang, Hyun-Woo

    2015-01-01

    A novel thin film transfer mechanism has been studied and developed to transfer chemically reduced graphene oxide (r-GO) thin film using a roll-to-roll printing system. We discover that shear stress generated on the silicon rubber stamp surface facilitates delamination of the deposited r-GO thin film efficiently.A roll-to-roll apparatus is assembled to demonstrate the shear-induced transfer printing in a large scale printing system. Shear stress is applied on the stamp surface by rotating the...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-01-15

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

  19. Influence of neodymium concentration on excitation and emission properties of Nd doped gallium oxide nanocrystalline films

    OpenAIRE

    Podhorodecki, A; Banski, M; J. Misiewicz; Lecerf, Céline; Marie, P.; Cardin, J.; Portier, X.

    2010-01-01

    International audience; Articles you may be interested in Investigation on the compensation effect of residual carbon impurities in low temperature grown Mg doped GaN films J. Appl. Phys. 115, 163704 (2014); 10.1063/1.4873957 Elevated temperature dependent transport properties of phosphorus and arsenic doped zinc oxide thin films J. Appl. Phys. 114, 223709 (2013); 10.1063/1.4845855 Improvement of (004) texturing by slow growth of Nd doped TiO2 films J. Appl. Phys. 112, 113505 (2012); 10.1063/...

  20. The origin of local strain in highly epitaxial oxide thin films.

    Science.gov (United States)

    Ma, Chunrui; Liu, Ming; Chen, Chonglin; Lin, Yuan; Li, Yanrong; Horwitz, J S; Jiang, Jiechao; Meletis, E I; Zhang, Qingyu

    2013-10-31

    The ability to control the microstructures and physical properties of hetero-epitaxial functional oxide thin films and artificial structures is a long-sought goal in functional materials research. Normally, only the lattice misfit between the film and the substrate is considered to govern the physical properties of the epitaxial films. In fact, the mismatch of film unit cell arrangement and the Surface-Step-Terrace (SST) dimension of the substrate, named as "SST residual matching", is another key factor that significantly influence the properties of the epitaxial film. The nature of strong local strain induced from both lattice mismatch and the SST residual matching on ferroelectric (Ba,Sr)TiO3 and ferromagnetic (La,Ca)MnO3 thin films are systematically investigated and it is demonstrated that this combined effect has a dramatic impact on the physical properties of highly epitaxial oxide thin films. A giant anomalous magnetoresistance effect (~10(10)) was achieved from the as-designed vicinal surfaces.

  1. Aluminum-doped zinc oxide thin films grown on various substrates using facing target sputtering system

    Science.gov (United States)

    Kim, Hwa-Min; Lee, Chang Hyun; Shon, Sun Young; Kim, Bong Hwan

    2017-11-01

    Aluminum-doped zinc oxide (AZO) films were fabricated on various substrates, such as glass, polyethylene naphthalate (PEN), and polyethylene terephthalate (PET), at room temperature using a facing target sputtering (FTS) system with hetero ZnO and Al2O3 targets, and their electrical and optical properties were investigated. The AZO film on glass exhibited compressive stress while the films on the plastic substrates showed tensile stress. These stresses negatively affected the crystalline quality of the AZO films, and it is suggested that the poor crystalline quality of the films may be related to the neutral Al-based defect complexes formed in the films; these complexes act as neutral impurity scattering centers. AZO films with good optoelectronic properties could be formed on the glass and plastic substrates by the FTS technique using the hetero targets. The AZO films deposited on the glass, PEN, and PET substrates showed very low resistivities, of 5.0 × 10-4 Ω cm, 7.0 × 10-4 Ω cm, and 7.4 × 10-4 Ω cm, respectively. Further, the figure merit of the AZO film formed on the PEN substrate in the visible range (400-700 nm) was significantly higher than that of the AZO film on PET and similar to that of the AZO film on glass. Finally, the average transmittances of the films in the visible range (400-700 nm) were 83.16% (on glass), 76.3% (on PEN), and 78.16% (on PET).

  2. Chemical bonding and optoelectrical properties of ruthenium doped yttrium oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Lei; Han, Jiecai [Harbin Institute of Technology, Harbin 150080 (China); Zhu, Jiaqi, E-mail: zhujq@hit.edu.cn [Harbin Institute of Technology, Harbin 150080 (China); Zhu, Yuankun [Harbin Institute of Technology, Harbin 150080 (China); Schlaberg, H.Inaki [North China Electric Power University, Beijing 102206 (China)

    2013-11-15

    Graphical abstract: IR transmittance of various transparent conductive materials (RYO films grown under RT, 400 °C and 600 °C, ITO films [2], Carbon Nano tube films [11], metal/dielectric multilayers [12]). - Highlights: • Y{sub 2}O{sub 3}:Ru (RYO) films were prepared on ZnS substrates by reactive magnetron sputtering. • Ru doping significantly decreases the resistivity and extends the transparent range. • Optical and electrical properties of RYO films can be tuned by substrate temperatures. • The RYO films exhibit excellent far-IR transmittance and electrical property. - Abstract: Highly infrared transparent conductive ruthenium doped yttrium oxide (RYO) films were deposited on zinc sulfide and glass substrates by reactive magnetron sputtering. The structural, optical, and electrical properties of the films as a function of growth temperature were studied. It is shown that the sputtered RYO thin films are amorphous and smooth surface is obtained. The infrared transmittance of the films increases with increasing the growth temperature. RYO films maintain greater than ∼65% transmittance over a wide wavelength range from 2.5 μm to 12 μm and the highest transmittance value reaches 73.3% at ∼10 μm. With increasing growth temperature, the resistivity changed in a wide range and lowest resistivity of about 3.36 × 10{sup −3} Ω cm is obtained at room temperature. The RYO thin films with high conductivity and transparency in IR spectral range would be suitable for infrared optical and electromagnetic shielding devices.

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

    Science.gov (United States)

    Wen, Qi-Ye; Zhang, Huai-Wu; Yang, Qing-Hui; Chen, Zhi; Long, Yang; Jing, Yu-Lan; Lin, Yuan; Zhang, Pei-Xin

    2012-06-01

    A tunable hybrid metamaterial absorber (MA) in the microwave band was designed, fabricated and characterized. The hybrid MA was realized by incorporating a VO2 film into the conventional resonant MA. By thermally triggering the insulator-metal phase transition of the VO2 film, the impedance match condition was broken and a deep amplitude modulation of about 63.3% to the electromagnetic wave absorption was achieved. A moderate blue-shift of the resonance frequency was observed which is promising for practical applications. This VO2-based MA exhibits many advantages such as strong tunability, frequency agility, simple fabrication and ease of scaling to the terahertz band.

  4. Study of film graphene/graphene oxide obtained by partial reduction chemical of oxide graphite; Estudo de filme de grafeno/oxido de grafeno obtido por reducao quimica parcial do oxido de grafite

    Energy Technology Data Exchange (ETDEWEB)

    Gascho, J.L.S.; Costa, S.F.; Hoepfner, J.C.; Pezzin, S.H., E-mail: juliagascho@hotmail.com [Universidade do Estado de Santa Catarina (UDESC), Joinville, SC (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais

    2014-07-01

    This study investigated the morphology of graphene/graphene oxide film obtained by partial chemical reduction of graphite oxide (OG) as well as its resistance to solvents. Films of graphene/graphene oxide are great candidates for replacement of indium oxide doped with tin (ITO) in photoelectric devices. The OG was obtained from natural graphite, by Hummer's method modified, and its reduction is made by using sodium borohydride. Infrared spectroscopy analysis of Fourier transform (FTIR), Xray diffraction (XRD) and scanning electron microscopy, high-resolution (SEM/FEG) for the characterization of graphene/graphene oxide film obtained were performed. This film proved to be resilient, not dispersing in any of the various tested solvents (such as ethanol, acetone and THF), even under tip sonication, this resistance being an important property for the applications. Furthermore, the film had a morphology similar to that obtained by other preparation methods.(author)

  5. Structural, optical and electrochemical properties of F-doped vanadium oxide transparent semiconducting thin films

    Science.gov (United States)

    Mousavi, M.; Khorrami, Gh. H.; Kompany, A.; Yazdi, Sh. Tabatabai

    2017-12-01

    In this study, F-doped vanadium oxide thin films with doping levels up to 60 at % were prepared by spray pyrolysis method on glass substrates. To measure the electrochemical properties, some films were deposited on fluorine-tin oxide coated glass substrates. The effect of F-doping on the structural, electrical, optical and electrochemical properties of vanadium oxide samples was investigated. The X-ray diffractographs analysis has shown that all the samples grow in tetragonal β-V2O5 phase structure with the preferred orientation of [200]. The intensity of (200) peak belonging to β-V2O5 phase was strongest in the undoped vanadium oxide film. The scanning electron microscopy images show that the samples have nanorod- and nanobelt-shaped structure. The size of the nanobelts in the F-doped vanadium oxide films is smaller than that in the pure sample and the width of the nanobelts increases from 30 to 70 nm with F concentration. With increasing F-doping level from 10 to 60 at %, the resistivity, the transparency and the optical band gap decrease from 111 to 20 Ω cm, 70 to 50% and 2.4 to 2.36 eV, respectively. The cyclic voltammogram (CV) results show that the undoped sample has the most extensive CV and by increasing F-doping level from 20 to 60 at %, the area of the CV is expanded. The anodic and cathodic peaks in F-doped samples are stronger.

  6. Transistor Characteristics of Zinc Oxide Active Layers at Various Zinc Acetate Dihydrate Solution Concentrations of Zinc Oxide Thin-film

    Directory of Open Access Journals (Sweden)

    H.C. You

    2015-04-01

    Full Text Available This paper presents a technique involving a sol-gel deposition method applied to the deposition of zinc oxide thin film for a transistor as a semiconductor layer. This method was used for manufacturing the essential thin films of II-VI semiconductors. Zinc oxide (ZnO bottom-gate (BG thin-film transistors (TFTs have been successfully fabricated at low temperatures. We investigated the electrical characteristics of ZnO thin-film transistors at various concentrations of ZnO solution: 0.02 M, 0.03 M, 0.04 M, and 0.05 M. All of the ZnO films exhibited a hexagonal wurtzite polycrystalline structure with (002 preferred orientation. Atomic force microscopy (AFM revealed the formation of grains or clusters as a result of the accumulation of nanoparticles, and the grain size increased with increasing solution concentration. The coated ZnO films were employed as the active channel layer in thin-film transistors, and the impact of the solution concentration on the device performance was examined. As the solution concentration was increased, the field-effect mobility increased from 1 × 10–4 cm2/V-s to 1.2 × 10–1 cm2/V-s, the threshold voltage increased from 4.8 V to 11.1 V, and the Ion/Ioff ratio increased from 104 to 106. The on-off ratio (Ion/off was found to be 106. The 0.05 M ZnO solution performed optimally.

  7. Effect of hafnium-incorporation on the microstructure and dielectric properties of cobalt ferrite ceramics

    Science.gov (United States)

    Wells, Stephen Josiah

    The effect of hafnium ion (Hf4+) incorporation in cobalt ferrite (CFO) was studied. Samples of Hf substituted CFO ceramic (CoFe 2-xHfxO4), were synthesized in the laboratory with hafnium concentrations ranging from x=0.000 to x=0.200. X-ray diffraction scans show that the Hafnium CFO crystalizes in the inverse spinel phase. Inclusion of hafnium causes lattice expansion, increasing the lattice parameter from 8.374 A for pure CoFe2O4 to 8.391 A for the highest concentration of hafnium tested (x=0.020). The dielectric properties of CFO are greatly enhanced by inclusion of hafnium. The enhancement is due to the distortion on the lattice from the larger Hf-ions substituting the smaller Fe-ions. Frequency variation of the dielectric properties is well modeled by the modified Debye function, which takes into account multiple ions contributing to relaxation.

  8. Physical and electrical properties of thermal oxidized Sm{sub 2}O{sub 3} gate oxide thin film on Si substrate: Influence of oxidation durations

    Energy Technology Data Exchange (ETDEWEB)

    Goh, Kian Heng; Haseeb, A.S.M.A.; Wong, Yew Hoong, E-mail: yhwong@um.edu.my

    2016-05-01

    Growth of 150 nm Sm{sub 2}O{sub 3} films by sputtered pure samarium metal film on silicon substrates and followed by thermal oxidation process in oxygen ambient at 700 °C through various oxidation durations (5 min, 10 min, 15 min and 20 min) has been carried out. The crystallinity of Sm{sub 2}O{sub 3} film and existence of interfacial layer have been evaluated by X-ray diffraction, Fourier transform infrared and Raman analysis. Crystallite size and microstrain of Sm{sub 2}O{sub 3} were estimated by Williamson–Hall plot analysis. Calculated crystallite size of Sm{sub 2}O{sub 3} from Scherrer equation has similar trend with the value from Williamson–Hall plot. The presence of interfacial layer is supported by composition line scan by energy dispersive X-ray spectroscopy analysis. The surface roughness and surface topography of Sm{sub 2}O{sub 3} film were examined by atomic force microscopy analysis. The electrical characterization revealed that 15 min of oxidation durations with smoothest surface has highest breakdown voltage, lowest leakage current density and highest barrier height value. - Highlights: • Thermal oxidation of sputtered pure metallic Sm in oxygen ambient • Formation of polycrystalline Sm{sub 2}O{sub 3} and semi-polycrystalline interfacial layers • Optimization of oxidation duration of pure metallic Sm in oxygen ambient • Enhanced electrical performance with smooth surface and increased barrier height.

  9. Toward an Understanding of Thin-Film Transistor Performance in Solution-Processed Amorphous Zinc Tin Oxide (ZTO) Thin Films.

    Science.gov (United States)

    Sanctis, Shawn; Koslowski, Nico; Hoffmann, Rudolf; Guhl, Conrad; Erdem, Emre; Weber, Stefan; Schneider, Jörg J

    2017-06-28

    Amorphous zinc tin oxide (ZTO) thin films are accessible by a molecular precursor approach using mononuclear zinc(II) and tin(II) compounds with methoxyiminopropionic acid ligands. Solution processing of two precursor solutions containing a mixture of zinc and tin(II)-methoxyiminopropinato complexes results in the formation of smooth homogeneous thin films, which upon calcination are converted into the desired semiconducting amorphous ZTO thin films. ZTO films integrated within a field-effect transistor (FET) device exhibit an active semiconducting behavior in the temperature range between 250 and 400 °C, giving an increased performance, with mobility values between μ = 0.03 and 5.5 cm 2 /V s, with on/off ratios increasing from 10 5 to 10 8 when going from 250 to 400 °C. Herein, our main emphasis, however, was on an improved understanding of the material transformation pathway from weak to high performance of the semiconductor in a solution-processed FET as a function of the processing temperature. We have correlated this with the chemical composition and defects states within the microstructure of the obtained ZTO thin film via photoelectron spectroscopy (X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy), Auger electron spectroscopy, electron paramagnetic resonance spectroscopy, atomic force microscopy, and photoluminescence investigations. The critical factor observed for the improved performance within this ZTO material could be attributed to a higher tin concentration, wherein the contributions of point defects arising from the tin oxide within the final amorphous ZTO material play the dominant role in governing the transistor performance.

  10. Controlled crumpling of graphene oxide films for tunable optical transmittance.

    Science.gov (United States)

    Thomas, Abhay V; Andow, Brandon C; Suresh, Shravan; Eksik, Osman; Yin, Jie; Dyson, Anna H; Koratkar, Nikhil

    2015-06-03

    The delamination buckling approach provides a facile means to dynamically control the optical transmittance of extremely flexible and stretchable graphene oxide coatings with fast response time. Such graphene oxide coatings can be deposited by scalable solution-processing methods for potential applications in dynamic glazing. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Laser Irradiation of Metal Oxide Films and Nanostructures: Applications and Advances.

    Science.gov (United States)

    Palneedi, Haribabu; Park, Jung Hwan; Maurya, Deepam; Peddigari, Mahesh; Hwang, Geon-Tae; Annapureddy, Venkateswarlu; Kim, Jong-Woo; Choi, Jong-Jin; Hahn, Byung-Dong; Priya, Shashank; Lee, Keon Jae; Ryu, Jungho

    2018-02-07

    Recent technological advances in developing a diverse range of lasers have opened new avenues in material processing. Laser processing of materials involves their exposure to rapid and localized energy, which creates conditions of electronic and thermodynamic nonequilibrium. The laser-induced heat can be localized in space and time, enabling excellent control over the manipulation of materials. Metal oxides are of significant interest for applications ranging from microelectronics to medicine. Numerous studies have investigated the synthesis, manipulation, and patterning of metal oxide films and nanostructures. Besides providing a brief overview on the principles governing the laser-material interactions, here, the ongoing efforts in laser irradiation of metal oxide films and nanostructures for a variety of applications are reviewed. Latest advances in laser-assisted processing of metal oxides are summarized. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Magnetoelectric hexaferrite thin film growth on oxide conductive layer for applications at low voltages

    Energy Technology Data Exchange (ETDEWEB)

    Zare, Saba, E-mail: zare.s@husky.neu.edu; Izadkhah, Hessam; Vittoria, Carmine

    2016-08-15

    Magnetoelectric (ME) M-type hexaferrite thin films were deposited on conductive oxide layer of Indium–Tin Oxide (ITO) in order to lower applied voltages to observe ME effects at room temperature. The thin film of ME hexaferrites, SrCo{sub 2}Ti{sub 2}Fe{sub 8}O{sub 19}/ITO buffer layer, were deposited on sapphire substrate using Pulsed Laser Deposition (PLD) technique. The film exhibited ME effects as confirmed by vibrating sample magnetometer (VSM) in voltages as low as 0.5 V. Without the oxide conductive layer the required voltages to observe ME effects were typically 500 V and higher. The thin films were characterized by X-ray diffractometer, scanning electron microscope, energy-dispersive spectroscopy, vibrating sample magnetometer, and ferromagnetic resonance. We measured saturation magnetization of 1064 G, and coercive field of 20 Oe for these thin films. The change rate in remanence magnetization was measured with the application of DC voltage at room temperature and it gave rise to changes in remanence in the order of 15% with the application of only 0.5 V (DC voltage). We deduced a ME coupling, α, of 5×10{sup −10} s m{sup −1} in SrCo{sub 2}Ti{sub 2}Fe{sub 8}O{sub 19} thin films. - Highlights: • Magnetoelectric (ME) hexaferrite thin films were deposited on conductive ITO. • Much lower voltage is required in order observe ME effects, as low as 0.5V. • ME films with conductive layers appear to be very promising in future IC circuitry.

  13. Transparent conducting oxide layers for thin film silicon solar cells

    NARCIS (Netherlands)

    Rath, J.K.|info:eu-repo/dai/nl/304830585; Liu, Y.|info:eu-repo/dai/nl/304831743; de Jong, M.M.|info:eu-repo/dai/nl/325844208; de Wild, J.|info:eu-repo/dai/nl/314641378; Schuttauf, J.A.|info:eu-repo/dai/nl/314118039; Brinza, M.|info:eu-repo/dai/nl/304823325; Schropp, R.E.I.|info:eu-repo/dai/nl/072502584

    2009-01-01

    Texture etching of ZnO:1%Al layers using diluted HCl solution provides excellent TCOs with crater type surface features for the front contact of superstrate type of thin film silicon solar cells. The texture etched ZnO:Al definitely gives superior performance than Asahi SnO2:F TCO in case of

  14. Gas sensing application of nanocrystalline zinc oxide thin films ...

    Indian Academy of Sciences (India)

    Experimental data revealed the sensors to be more selective to NO2 gas with satisfactory response and recovery time. Keywords. ZnO; thin film; spray .... to measure gas sens- ing characteristics due to the sluggish recovery kinetics. .... AuS by reaction of H2S on the gold nanoparticles was also reported by Shirsat et al.72 ...

  15. Assessment of Cellulose Acetate/Manganese Oxide Thin Film as ...

    Indian Academy of Sciences (India)

    5

    industry during the last few decades, large amounts of chemical compounds and contaminants have emerged to the environment [1]. The analysis of these .... at 4.0°C. To probe the selectivity of the synthesized adsorbents, batch adsorption experiments were performed by adding 10 mg of each thin film (CA/Mn-1 and ...

  16. Chemical Vapor Deposition of Aluminum Oxide Thin Films

    Science.gov (United States)

    Vohs, Jason K.; Bentz, Amy; Eleamos, Krystal; Poole, John; Fahlman, Bradley D.

    2010-01-01

    Chemical vapor deposition (CVD) is a process routinely used to produce thin films of materials via decomposition of volatile precursor molecules. Unfortunately, the equipment required for a conventional CVD experiment is not practical or affordable for many undergraduate chemistry laboratories, especially at smaller institutions. In an effort to…

  17. Atomic-Layer-Deposition of Indium Oxide Nano-films for Thin-Film Transistors.

    Science.gov (United States)

    Ma, Qian; Zheng, He-Mei; Shao, Yan; Zhu, Bao; Liu, Wen-Jun; Ding, Shi-Jin; Zhang, David Wei

    2018-01-09

    Atomic-layer-deposition (ALD) of In 2 O 3 nano-films has been investigated using cyclopentadienyl indium (InCp) and hydrogen peroxide (H 2 O 2 ) as precursors. The In 2 O 3 films can be deposited preferentially at relatively low temperatures of 160-200 °C, exhibiting a stable growth rate of 1.4-1.5 Å/cycle. The surface roughness of the deposited film increases gradually with deposition temperature, which is attributed to the enhanced crystallization of the film at a higher deposition temperature. As the deposition temperature increases from 150 to 200 °C, the optical band gap (E g ) of the deposited film rises from 3.42 to 3.75 eV. In addition, with the increase of deposition temperature, the atomic ratio of In to O in the as-deposited film gradually shifts towards that in the stoichiometric In 2 O 3 , and the carbon content also reduces by degrees. For 200 °C deposition temperature, the deposited film exhibits an In:O ratio of 1:1.36 and no carbon incorporation. Further, high-performance In 2 O 3 thin-film transistors with an Al 2 O 3 gate dielectric were achieved by post-annealing in air at 300 °C for appropriate time, demonstrating a field-effect mobility of 7.8 cm 2 /V⋅s, a subthreshold swing of 0.32 V/dec, and an on/off current ratio of 10 7 . This was ascribed to passivation of oxygen vacancies in the device channel.

  18. Atomic-Layer-Deposition of Indium Oxide Nano-films for Thin-Film Transistors

    Science.gov (United States)

    Ma, Qian; Zheng, He-Mei; Shao, Yan; Zhu, Bao; Liu, Wen-Jun; Ding, Shi-Jin; Zhang, David Wei

    2018-01-01

    Atomic-layer-deposition (ALD) of In2O3 nano-films has been investigated using cyclopentadienyl indium (InCp) and hydrogen peroxide (H2O2) as precursors. The In2O3 films can be deposited preferentially at relatively low temperatures of 160-200 °C, exhibiting a stable growth rate of 1.4-1.5 Å/cycle. The surface roughness of the deposited film increases gradually with deposition temperature, which is attributed to the enhanced crystallization of the film at a higher deposition temperature. As the deposition temperature increases from 150 to 200 °C, the optical band gap (Eg) of the deposited film rises from 3.42 to 3.75 eV. In addition, with the increase of deposition temperature, the atomic ratio of In to O in the as-deposited film gradually shifts towards that in the stoichiometric In2O3, and the carbon content also reduces by degrees. For 200 °C deposition temperature, the deposited film exhibits an In:O ratio of 1:1.36 and no carbon incorporation. Further, high-performance In2O3 thin-film transistors with an Al2O3 gate dielectric were achieved by post-annealing in air at 300 °C for appropriate time, demonstrating a field-effect mobility of 7.8 cm2/Vṡs, a subthreshold swing of 0.32 V/dec, and an on/off current ratio of 107. This was ascribed to passivation of oxygen vacancies in the device channel.

  19. Synthesis of Hafnium-Based Ceramic Materials for Ultra-High Temperature Aerospace Applications

    Science.gov (United States)

    Johnson, Sylvia; Feldman, Jay

    2004-01-01

    This project involved the synthesis of hafnium (Hf)-based ceramic powders and Hf-based precursor solutions that were suitable for preparation of Hf-based ceramics. The Hf-based ceramic materials of interest in this project were hafnium carbide (with nominal composition HE) and hafnium dioxide (HfO2). The materials were prepared at Georgia Institute of Technology and then supplied to research collaborators Dr. Sylvia Johnson and Dr. Jay Feldman) at NASA Ames Research Center.

  20. Mechanical properties and scratch resistance of filtered-arc-deposited titanium oxide thin films on glass

    Energy Technology Data Exchange (ETDEWEB)

    Borrero-Lopez, Oscar, E-mail: oborlop@unex.es [Departamento de Ingenieria Mecanica, Energetica y de los Materiales, Universidad de Extremadura, 06071, Badajoz (Spain); School of Materials Science and Engineering, University of New South Wales NSW 2052, Sydney (Australia); Hoffman, Mark [School of Materials Science and Engineering, University of New South Wales NSW 2052, Sydney (Australia); Bendavid, Avi; Martin, Phil J. [CSIRO Materials Science and Engineering, P.O. Box 218, Lindfield NSW 2070 (Australia)

    2011-09-01

    The mechanical properties and the scratch resistance of titanium oxide (TiO{sub 2}) thin films on a glass substrate have been investigated. Three films, with crystalline (rutile and anatase) and amorphous structures, were deposited by the filtered cathodic vacuum arc deposition technique on glass, and characterized by means of nanoindentation and scratch tests. The different damage modes (arc-like, longitudinal and channel cracks in the crystalline films; Hertzian cracks in the amorphous film) were assessed by means of optical and focused ion beam microscopy. In all cases, the deposition of the TiO{sub 2} film improved the contact-mechanical properties of uncoated glass. Crystalline films were found to possess a better combination of mechanical properties (i.e. elastic modulus up to 221 GPa, hardness up to 21 GPa, and fracture strength up to 3.6 GPa) than the amorphous film. However, under cyclic sliding contact above the critical fracture load, the amorphous film was found to withstand a higher number of cycles. The results are expected to provide useful insight for the design of optical coatings with improved contact-damage resistance.

  1. Microporous Ni-doped TiO2 film photocatalyst by plasma electrolytic oxidation.

    Science.gov (United States)

    Yao, Zhongping; Jia, Fangzhou; Tian, Shujun; Li, ChunXiang; Jiang, Zhaohua; Bai, Xuefeng

    2010-09-01

    Ni-doped TiO2 film catalysts were prepared by a plasma electrolytic oxidation (PEO) method and were mainly characterized by means of SEM, EDS, XRD, XPS, and DRS, respectively. The effects of Ni doping on the structure, composition and optical absorption property of the film catalysts were investigated along with their inherent relationships. The results show that the film catalyst is composed of anatase and rutile TiO2 with microporous structure. Doping Ni changes the phase composition and the lattice parameters (interplanar crystal spacing and cell volume) of the films. The optical absorption range of TiO2 film gradually expands and shifts to the red with increasing dosages. Both direct and indirect transition band gaps of the TiO2 films are deduced consequently. Moreover, the photocatalytic activity of the film catalysts for splitting Na2S+Na2SO3 solution into H2 is enhanced by doping with an appropriate amount of Ni. The as-prepared TiO2 film catalyst doping with 10 g/L of Ni(Ac)2 presents the highest photocatalytic reducing activity.

  2. Characterization of iron oxide thin films prepared by sol-gel processing.

    Science.gov (United States)

    Karakuscu, Aylin; Ozenbas, Macit

    2008-02-01

    Iron oxide thin films were prepared by spin-coating a gel solution of iron(III) nitrate dissolved in 2-methoxyethanol and acetylacetone on glass and quartz substrates. The film thickness was adjusted by changing the spinning rate of the spin coater. Annealing was carried out between 300 degrees C to 600 degrees C to investigate the phases present in the films. Viscosity of the main solution was found as 0.0035 Pa.s by viscosity measurement. TGA/DTA analyses showed that heat treatment should be done between 330 degrees C and 440 degrees C in order to produce maghemite thin films. SEM studies showed that single layer thickness of the films were between 65 and 80 nm. The structural characteristics were evaluated by changing the experimental parameters which are annealing temperature, annealing time and thickness of the films. From the X-ray diffraction analysis, maghemite formation was observed with decreasing annealing temperature, annealing time and film thickness. TEM results verified the presence of the maghemite phase by electron diffraction and selected area electron diffraction (SAED) methods. According to UV-Vis results transmittance of the films decreases with increasing annealing temperature.

  3. Synthesis of Cobalt Oxides Thin Films Fractal Structures by Laser Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    P. Haniam

    2014-01-01

    Full Text Available Thin films of cobalt oxides (CoO and Co3O4 fractal structures have been synthesized by using laser chemical vapor deposition at room temperature and atmospheric pressure. Various factors which affect the density and crystallization of cobalt oxides fractal shapes have been examined. We show that the fractal structures can be described by diffusion-limited aggregation model and discuss a new possibility to control the fractal structures.

  4. Influence of different factors on the destruction of films based on polylactic acid and oxidized polyethylene

    Science.gov (United States)

    Podzorova, M. V.; Tertyshnaya, Yu. V.; Pantyukhov, P. V.; Shibryaeva, L. S.; Popov, A. A.; Nikolaeva, S.

    2016-11-01

    Influence of different environmental factors on the degradation of film samples based on polylactic acid and low density polyethylene with the addition of oxidized polyethylene was studied in this work. Different methods were used to find the relationship between degradation and ultraviolet, moisture, oxygen. It was found that the addition of oxidized polyethylene, used as a model of recycled polyethylene, promotes the degradation of blends.

  5. Influence of thin fluoropolymer film deposition on wettability of the silicon oxide nanowires array

    Directory of Open Access Journals (Sweden)

    Baranov Evgeniy

    2016-01-01

    Full Text Available In this work, we studied influence of fluoropolymer thin film deposition on wettability of the silicon oxide nanowires array. Deposition of fluoropolymer coating on the silicon oxide nanowires array changes the surface properties from hydrophilic to hydrophobic, and micro and nano scale surface roughness does not change significantly. In addition, it was shown that the deposition of fluoropolymer coating on nanowires protects the nanostructures from bundling together as a result of the attractive capillary forces that arise during evaporative drying.

  6. Low-Temperature UV-Assisted Fabrication of Metal Oxide Thin Film Transistor

    Science.gov (United States)

    Zhu, Shuanglin

    Solution processed metal oxide semiconductors have attracted intensive attention in the last several decades and have emerged as a promising candidate for the application of thin film transistor (TFT) due to their nature of transparency, flexibility, high mobility, simple processing technique and potential low manufacturing cost. However, metal oxide thin film fabricated by solution process usually requires a high temperature (over 300 °C), which is above the glass transition temperature of some conventional polymer substrates. In order to fabricate the flexible electronic device on polymer substrates, it is necessary to find a facile approach to lower the fabrication temperature and minimize defects in metal oxide thin film. In this thesis, the electrical properties dependency on temperature is discussed and an UV-assisted annealing method incorporating Deep ultraviolet (DUV)-decomposable additives is demonstrated, which can effectively improve electrical properties solution processed metal oxide semiconductors processed at temperature as low as 220 °C. By studying a widely used indium oxide (In2O3) TFT as a model system, it is worth noted that compared with the sample without UV treatment, the linear mobility and saturation mobility of UV-annealing sample are improved by 56% and 40% respectively. Meanwhile, the subthreshold swing is decreased by 32%, indicating UV-treated device could turn on and off more efficiently. In addition to pure In2O3 film, the similar phenomena have also been observed in indium oxide based Indium-Gallium-Zinc Oxide (IGZO) system. These finding presented in this thesis suggest that the UV assisted annealing process open a new route to fabricate high performance metal oxide semiconductors under low temperatures.

  7. Deposition, characterization and optimization of zinc oxide thin film for piezoelectric cantilevers

    Science.gov (United States)

    Wang, Peihong; Du, Hejun; Shen, Shengnan; Zhang, Mingsheng; Liu, Bo

    2012-10-01

    In this work, piezoelectric zinc oxide (ZnO) thin films are deposited under different deposition conditions using RF magnetron sputtering method. The influence of RF power, O2/(Ar + O2) gas ratio and sputtering pressure on the deposition rate, crystalline structures, surface roughness and composition purity of ZnO film are investigated by X-ray Diffractometer (XRD), scanning electron microscopy (SEM), atom force microscopy (AFM) and energy dispersive X-ray spectroscopy (EDS). All the fabricated ZnO films have a preferred ZnO(0 0 2) orientation. When the gas ratio of O2/(Ar + O2) is 25% and the working pressure is 0.8 Pa, the grain size in the ZnO thin film is of the largest and the ZnO film has a very smooth and dense surface. The SEM cross-sectional image of the ZnO film confirms that the ZnO thin film has a columnar structure and the c-axis is perpendicular to the substrate surface. The EDS analysis shows the ZnO film has only Zn and O elements. Different ZnO film based piezoelectric micro cantilevers are fabricated using micromachining techniques and the dynamic response of these piezoelectric cantilevers are measured by laser Doppler vibrometer (LDV). The tested results from LDV show that the deflection of the piezoelectric cantilever is linear with the driving voltage. The transverse piezoelectric constant d31 of the ZnO thin film deposited under best conditions is calculated as -3.21 pC/N by the LDV data. This value is higher than other published works. In future, these ZnO thin films will be used in our ongoing project for the design, simulation and fabrication of smart slider with a built-in ZnO sensor/actuator in the hard disk drives.

  8. Oxidation of Light Alkanes Using Photocatalytic Thin Films

    Science.gov (United States)

    2006-01-01

    thermodynamically unfavorable reaction. Titanium dioxide ( TiO2 ) is the most prominent and widely used semiconductor in the field of photocatalysis . Titania has...2.5.1 Mixed Oxide Systems Mixed oxide systems typically consist of TiO2 with small quantities (ង%) of a second metal oxide added...demonstrated that mixing TiO2 with ZrO2 and SiO2 improved photocatalytic rates by more than 2 times compared to plain TiO2 . Small quantities (ក

  9. Local mechanical and electromechanical properties of the P(VDF-TrFE)-graphene oxide thin films

    Science.gov (United States)

    Silibin, M. V.; Bystrov, V. S.; Karpinsky, D. V.; Nasani, N.; Goncalves, G.; Gavrilin, I. M.; Solnyshkin, A. V.; Marques, P. A. A. P.; Singh, Budhendra; Bdikin, I. K.

    2017-11-01

    Recently, many organic materials, including carbon materials such as carbon nanotubes (CNTs) and graphene (single-walled carbon sheet structure) were studied in order to improve their mechanical and electrical properties. In particular, copolymers of poly (vinylidene fluoride) and poly trifluoroethylene [P(VDF-TrFE)] are promising materials, which can be used as probes, sensors, actuators, etc. Composite thin film of the copolymer P(VDF-TrFE) with graphene oxide (GO) were prepared by spin coating. The obtained films were investigated using piezoresponse force microscopy (PFM). The switching behavior, piezoelectric response, dielectric permittivity and mechanical properties of the films were found to depend on the presence of GO. For understanding the mechanism of piezoresponse evolution of the composite we used models of PVDF chain, its behavior in electrical field and computed the data for piezoelectric coefficients using HyperChem software. The summarized models of graphene oxide based on graphene layer from 96 carbon atoms C: with oxygen and OH groups and with COOH groups arranged by hydrogen were used for PVDF/Graphene oxide complex: 1) with H-side (hydrogen atom) connected from PVDF to graphene oxide, 2) with F-side (fluorine atom) connected from PVDF graphene oxide and 3) Graphene Oxide/PVDF with both sides (sandwich type). Experimental results qualitatively correlate with those obtained in the calculations.

  10. Properties of anodic oxides grown on a hafnium–tantalum–titanium thin film library

    Directory of Open Access Journals (Sweden)

    Andrei Ionut Mardare

    2014-01-01

    Full Text Available A ternary thin film combinatorial materials library of the valve metal system Hf–Ta–Ti obtained by co-sputtering was studied. The microstructural and crystallographic analysis of the obtained compositions revealed a crystalline and textured surface, with the exception of compositions with Ta concentration above 48 at.% which are amorphous and show a flat surface. Electrochemical anodization of the composition spread thin films was used for analysing the growth of the mixed surface oxides. Oxide formation factors, obtained from the potentiodynamic anodization curves, as well as the dielectric constants and electrical resistances, obtained from electrochemical impedance spectroscopy, were mapped along two dimensions of the library using a scanning droplet cell microscope. The semiconducting properties of the anodic oxides were mapped using Mott–Schottky analysis. The degree of oxide mixing was analysed qualitatively using x-ray photoelectron spectroscopy depth profiling. A quantitative analysis of the surface oxides was performed and correlated to the as-deposited metal thin film compositions. In the concurrent transport of the three metal cations during oxide growth a clear speed order of Ti > Hf > Ta was proven.

  11. Oxide films state analysis by IR spectroscopy based on the simple oscillator approximation

    Science.gov (United States)

    Volkov, N. V.; Yakutkina, T. V.; Karpova, V. V.

    2017-05-01

    Stabilization of structure-phase state in a wide temperature range is one of the most important problems of improving properties of oxide compounds. As such, the search of new effective methods for obtaining metal oxides with desired physic-chemical, electro-physical and thermal properties and their control is important and relevant. The aim of this work is identification features state of the oxide films of some metals Be, Al, Fe, Cu, Zr on the metal surface of the polycrystalline samples by infrared spectroscopy. To identify the resonance emission bands the algorithm of IR-spectra processing was developed and realized on the basis of table processor EXCEL-2010, which allow revealing characteristic resonance bands successfully and identification of inorganic chemical compounds. In the frame of simple oscillator model, resonance frequencies of normal vibrations of water and some inorganic compounds: metal oxides - Be, Al, Fe, Cu, Zr were calculated and characteristic frequencies for different states (aggregate, deformation, phase) were specified. By means of IR-spectroscopy fundamental possibility of revealing oxides films on metal substrate features state is shown, that allow development and optimization of the technology for production of the oxide films with desired properties.

  12. Magneto-optical Kerr effect studies of copper oxide and cobalt thin films

    Energy Technology Data Exchange (ETDEWEB)

    Fronk, Michael; Zahn, Dietrich R.T.; Salvan, Georgeta [Chemnitz University of Technology, Chemnitz (Germany); Mueller, Steve; Waechtler, Thomas; Schulz, Stefan E. [Fraunhofer Research Institution for Electronic Nano Systems ENAS, Chemnitz (Germany)

    2011-07-01

    Copper oxide is supposed to be a model material for tunnel-magneto-resistance (TMR) structures together with cobalt as ferromagnetic electrode. Therefore the magnetic properties of copper oxide itself are of interest and under investigation by various techniques. This contribution presents spectroscopic magneto-optical Kerr effect (MOKE) studies of thin films of this material. The films are produced by atomic layer deposition based on a Cu(I) {beta}-diketonate precursor at a process temperature of 120 C. The copper oxide films turned out to be magneto-optically active both in the spectral range around 2 eV and above 4 eV. Besides the experimental MOKE data the material-intrinsic magneto-optical Voigt constant extracted from optical model calculations are presented. Cobalt, the ferromagnetic counterpart in the TMR structures, was prepared by magnetron sputtering as thin films with different thicknesses. The Voigt constant of Co can be deduced from measurements on thick films (120 nm). It is investigated whether these data can be used to predict the magneto-optical response of thinner Co layers (10 nm).

  13. High rate deposition of transparent conducting oxide thin films by vacuum arc plasma evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Minami, Tadatsugu; Ida, Satoshi; Miyata, Toshihiro

    2002-09-02

    Transparent conducting oxide (TCO) thin films have been deposited at a high rate above 370 nm/min by vacuum arc plasma evaporation (VAPE) using sintered oxide fragments as the source material. It was found that the deposition rate of TCO films was strongly dependent on the deposition pressure, whereas the obtained electrical properties were relatively independent of the pressure. Resistivities of 5.6x10{sup -4} and 2.3x10{sup -4} {omega}{center_dot}cm and an average transmittance above 80% (with substrate included) in the visible range were obtained in Ga-doped ZnO (GZO) thin films deposited at 100 and 350 deg. C, respectively. In addition, a resistivity as low as 1.4x10{sup -4} {omega}{center_dot}cm and an average transmittance above 80% were also obtained in indium-tin-oxide (ITO) films deposited at 300 deg. C. The deposited TCO films exhibited uniform distributions of resistivity and thickness on large area substrates.

  14. Crystal Orientation and Electrical Properties of Tin Oxide Transparent Conducting Films Deposited on Rutile Surface

    Science.gov (United States)

    Sawada, Y.; Hashimoto, Y.; Hoshi, Y.; Uchida, T.; Kobayashi, S.; Sun, L.; Yue, B.

    2017-10-01

    Thin films of tin oxide (SnO2) without doping are attractive transparent conducting film since environmentally unfavorable elements of antimony or fluorine are eliminated. Tin oxide films without doping were fabricated very cheaply on (001) and (100) planes of single crystal of rutile (TiO2) by spray chemical vapor deposition (mist CVD). The film deposited on rutile (001) surface was poorly epitaxial (double domain) but with higher mobility (24 cm2 V-1 s-1) and lower resistivity (1.6×10-3 Ω cm) than that deposited on glass substrate (16 cm2 V-1 s-1 and 2.4×10-3 Ω cm) for reference. Deposition on rutile (100) surface resulted in better epitaxial growth (single domain). The mobility (39 cm2 V-1 s-1) and the carrier electron density (2.7×1020 cm-3) were much higher. The resistivity (6.2×10-4 Ω cm) was compatible with those doped with antimony or fluorine and will be the lowest among tin oxide films without doping.

  15. Functional doped metal oxide films. Zinc oxide (ZnO) as transparent conducting oxide (TCO) titanium dioxide (TiO{sub 2}) as thermographic phosphor and protective coating

    Energy Technology Data Exchange (ETDEWEB)

    Nebatti Ech-Chergui, Abdelkader

    2011-07-29

    spectra indicate that the red characteristic emission of TiO{sub 2}: Eu{sup 3+} due to electric dipole {sup 5}D{sub 0} {yields}{sup 7} F{sub 2} transition occurring after ultraviolet excitation is the strongest. The decay time of the phosphorescence after UV excitation with a Nd:YAG laser (355 nm, f=10Hz) is temperature dependent in the range from 200 C up to 400 C. Finally, it has been found that the lifetime show a significant dependency on europium concentration. The development of rutile phase of titanium dioxide films on stainless steel substrates as protective coatings were investigated. Generally the rutile phases of TiO{sub 2} thin films do not adhere well on stainless steel substrates. In order to improve the adhesion, stainless steel substrates were first coated with titanium films using cathodic vacuum arc deposition. Then these titanium coatings were partially transformed to the rutile phase of titanium dioxide by thermal oxidation. The presence of the rutile phase of titanium dioxide and metallic titanium were confirmed by XRD. Cavitation erosion was used for the first time to investigate the adhesion properties of these coatings. Cavitation erosion tests confirmed that rutile films with a Ti inter layer are well adherent to stainless steel substrates and protect the substrate from erosion. The total mass loss of the thermally oxidized samples of Ti coated stainless steel was found around 3.5 times lower than of the uncoated samples. (orig.)

  16. Photoluminescence properties of ZnO films grown on InP by thermally oxidizing metallic Zn films

    CERN Document Server

    Chen, S J; Zhang, J Y; Lu, Y M; Shen, D Z; Fan, X W

    2003-01-01

    Photoluminescence (PL) properties of ZnO films grown on (001) InP substrates by thermal oxidization of metallic Zn films, in which oxygen vacancies and interstitial Zn ions are compensated by P ions diffusing from (001) InP substrates, are investigated. X-ray diffraction spectra indicate that P ions have diffused into the Zn films and chemically combined with Zn ions to form Zn sub 3 P sub 2. Intense free exciton emission dominates the PL spectra of ZnO films with very weak deep-level emission. Low-temperature PL spectra at 79 K are dominated by neutral-donor bound exciton emission at 3.299 eV (I sub 4) with a linewidth of 17.3 meV and neutral-acceptor bound exciton emission at 3.264 eV. The free exciton emission increases with increasing temperature and eventually dominates the emission spectrum for temperature higher than 170 K. Furthermore, the visible emission around 2.3 eV correlated with oxygen deficiencies and interstitial Zn defects was quenched to a remarkable degree by P diffusing from InP substrate...

  17. Synthesis, surface tension, optical and dielectric properties of bismuth oxide thin film

    Directory of Open Access Journals (Sweden)

    Tezel Fatma Meydanerİ

    2017-03-01

    Full Text Available Bismuth oxide thin film was deposited by chemical bath deposition (CBD technique onto a glass substrate. The grain size (D, dislocation density (δ and number of crystallites per unit area (N, i.e. structural properties of the thin film were determined as 16 nm, 39.06× 10–4 line/nm2, 31.25 × 10–3 1/nm2, respectively. Optical transmittance properties of the thin film were investigated by using a UV-Vis spectrophotometer. The optical band gap (Eg for direct transitions, optical transmission (T %, reflectivity (R %, absorption, refractive index (nr, extinction coefficient (k, dielectric constant (∊ of the thin film were found to be 3.77 eV, 25.23 %, 32.25 %, 0.59, 3.62, 0.04 and 2.80, respectively. The thickness of the film was measured by AFM, and was found to be 128 nm. Contact angles of various liquids on the oxide thin film were determined by Zisman method, and surface tension was calculated to be 31.95 mN/m.

  18. High-κ Lanthanum Zirconium Oxide Thin Film Dielectrics from Aqueous Solution Precursors.

    Science.gov (United States)

    Woods, Keenan N; Chiang, Tsung-Han; Plassmeyer, Paul N; Kast, Matthew G; Lygo, Alexander C; Grealish, Aidan K; Boettcher, Shannon W; Page, Catherine J

    2017-03-29

    Metal oxide thin films are critical components in modern electronic applications. In particular, high-κ dielectrics are of interest for reducing power consumption in metal-insulator-semiconductor (MIS) field-effect transistors. Although thin-film materials are typically produced via vacuum-based methods, solution deposition offers a scalable and cost-efficient alternative. We report an all-inorganic aqueous solution route to amorphous lanthanum zirconium oxide (La 2 Zr 2 O 7 , LZO) dielectric thin films. LZO films were spin-cast from aqueous solutions of metal nitrates and annealed at temperatures between 300 and 600 °C to produce dense, defect-free, and smooth films with subnanometer roughness. Dielectric constants of 12.2-16.4 and loss tangents MIS devices utilizing LZO as the dielectric layer (1 kHz). Leakage currents <10 -7 A cm -2 at 4 MV cm -1 were measured for samples annealed at 600 °C. The excellent surface morphology, high dielectric constants, and low leakage current densities makes these LZO dielectrics promising candidates for thin-film transistor devices.

  19. Nitrogen-doped zinc oxide thin films biosensor for determination of uric acid.

    Science.gov (United States)

    Jindal, Kajal; Tomar, Monika; Gupta, Vinay

    2013-08-07

    Nitrogen-doped zinc oxide thin films (ZnO:N) have been realized as a potential matrix for the development of a uric acid biosensor. The correlation between the change in property of the ZnO film with N doping concentration and its biosensing response has been studied. The nitrogen dopant in a ZnO film alters its defects profile, thus improving the charge transfer characteristics and resulting in an enhanced peak oxidation current in the cyclic voltammogram in comparison to that of the pure ZnO film. The studies reveal that the bio-electrode based on the nitrogen-doped ZnO thin film matrix exhibits better sensitivity (1.1 mA mM(-1) cm(-2)) with linearity over a wide range (0.05 mM to 1.0 mM) of uric acid concentration. A comparatively low value (0.10 mM) of the Michaelis-Menten constant (Km) indicates high affinity of the immobilized uricase towards uric acid. The proposed ZnO:N thin films matrix-based uric acid-biosensor has good reproducibility, a long shelf-life (20 weeks) and high selectivity.

  20. Green synthesis of high conductivity silver nanoparticle-reduced graphene oxide composite films

    Science.gov (United States)

    Dinh, D. A.; Hui, K. S.; Hui, K. N.; Cho, Y. R.; Zhou, Wei; Hong, Xiaoting; Chun, Ho-Hwan

    2014-04-01

    A green facile chemical approach to control the dimensions of Ag nanoparticles-graphene oxide (AgNPs/GO) composites was performed by the in situ ultrasonication of a mixture of AgNO3 and graphene oxide solutions with the assistance of vitamin C acting as an environmentally friendly reducing agent at room temperature. With decreasing ultrasonication time, the size of the Ag nanoparticles decreased and became uniformly distributed over the surface of the GO nanosheets. The as-prepared AgNPs/rGO composite films were then formed using a spin coating method and reduced at 500 °C under N2/H2 gas flow for 1 h. Four-point probe measurements showed that the sheet resistance of the AgNPs/rGO films decreased with decreasing AgNPs size. The lowest sheet resistance of 270 Ω/sq was obtained in the film corresponding to 1 min of ultrasonication, which showed a 40 times lower resistivity than the rGO film (10.93 kΩ/sq). The formation mechanisms of the as-prepared AgNPs/rGO films are proposed. This study provides a guide to controlling the dimensions of AgNPs/rGO films, which might hold promise as advanced materials for a range of analytical applications, such as catalysis, sensors and microchips.

  1. Transparent and high gas barrier films based on poly(vinyl alcohol)/graphene oxide composites

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hye Min; Lee, Jung Kyoo; Lee, Heon Sang, E-mail: heonlee@dau.ac.kr

    2011-09-01

    Composites of poly(vinyl alcohol) (PVA) and graphene oxide (GO) were synthesized by a modified Hummers method and a solution-mixing method. GO was fully exfoliated in the PVA/GO composites. GO did not affect the crystallization of PVA during solvent evaporation. GO is itself an excellent gas barrier without any chemical reduction. The oxygen permeability of the PVA/GO (0.3 wt.%) composite coated film was 17 times lower than that of the pure poly(ethylene terephthalate) (PET) film, with 92% light transmittance at 550 nm. Composites of PVA and reduced graphene oxide (RGO) were synthesized by performing chemical reduction using hydrazine monohydrate. The oxygen permeability of the PVA/RGO (0.3 wt.%) composite coated film was 86 times lower than that of the pure PET film, with 73% light transmittance at 550 nm. The reduction of oxygen permeability was mainly attributed to the reduced oxygen solubility in the PVA/GO composite film, while it was attributed to both the reduced oxygen diffusivity and solubility in the PVA/RGO composite film.

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

    Energy Technology Data Exchange (ETDEWEB)

    Yurchuk, Ekaterina

    2015-02-06

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

  3. Doped zinc oxide films grown by hot-wire chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Abrutis, A., E-mail: adulfas.abrutis@chf.vu.lt; Silimavicius, L.; Kubilius, V.; Murauskas, T.; Saltyte, Z.; Plausinaitiene, V.

    2015-02-02

    Hot-wire chemical vapour deposition (CVD) was applied to grow zinc oxide (ZnO)-based transparent conducting oxide films. Indium (In)-, gallium (Ga)-, and aluminium (Al)-doped ZnO films were deposited at 400 °C on sapphire-R, Si (100) and glass substrates using a cold wall pulsed liquid injection CVD system containing nichrome wires installed in front of the substrate holder. Zn, In, Al 2,2,6,6-tetramethyl-3,5-heptanedionates, and Ga 3,5-pentanedionate dissolved in 1,2-dimethoxyethane were used as precursors. Hall measurements were performed to evaluate the resistivity, carrier concentration, and carrier mobility in doped ZnO films grown on sapphire substrates at wire currents of 6 A and 9 A. The influence of the dopant type, doping level, substrate, and wire heating current on crystallinity and the electrical and optical properties of the films was investigated and discussed. The best electrical properties were obtained for Al- and Ga-doped films grown at 9 A wire current (resistivity ≈ 1 × 10{sup −3} Ωcm, carrier mobility ≈ 50 cm{sup 2} V{sup −1} s{sup −1} and carrier concentration ≈ 1 × 10{sup 20} cm{sup −3}). The films exhibited a high transmittance in the mid-infrared region (≈ 90% at 2.5 μm). Additional annealing of the films at 400 °C in a mixture of Ar and hydrogen (10%) resulted in the increase in carrier concentration and mobility and in the reduction of film resistivity. - Highlights: • Hot-wire CVD process was applied for the growth of In-, Ga-, and Al-doped ZnO films. • Electrical and optical properties of as-deposited and annealed films were investigated. • Significant influence of film orientation on electrical properties was observed. • Films exhibited high carrier mobility (50–60 cm{sup 2} V{sup −1} s{sup −1}) and low resistivity (≤ 10{sup −3} Ωcm). • Films had high transmittance (~ 90%) in the mid-IR spectral range (at 2.5 μm)

  4. Preparation, characterization and dissolution of passive oxide film on the 400 series stainless steel surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Sathyaseelan, V.S.; Rufus, A.L.; Chandramohan, P.; Subramanian, H.; Velmurugan, S., E-mail: svelu@igcar.gov.in

    2015-12-15

    Full system decontamination of Primary Heat Transport (PHT) system of Pressurised Heavy Water Reactors (PHWRs) resulted in low decontamination factors (DF) on stainless steel (SS) surfaces. Hence, studies were carried out with 403 SS and 410 SS that are the material of construction of “End-Fitting body” and “End-Fitting Liner tubes”. Three formulations were evaluated for the dissolution of passive films formed over these alloys viz., i) Two-step process consisting of oxidation and reduction reactions, ii) Dilute Chemical Decontamination (DCD) and iii) High Temperature Process. The two-step and high temperature processes could dissolve the oxide completely while the DCD process could remove only 60%. Various techniques like XRD, Raman spectroscopy and SEM-EDX were used for assessing the dissolution process. The two-step process is time consuming, laborious while the high temperature process is less time consuming and is recommended for SS decontamination. - Graphical abstract: SEM micrograph of the oxide film formed in an autoclave over the 403 SS and 410 SS surfaces, the “End-Fitting Body and End-Fitting Liner” materials of Pressurized Heavy Water Reactor (PHWR). - Highlights: • The oxides formed over 403 and 410 SS are spinels similar to magnetite. • Oxide is duplex in nature with chromium rich inner layer. • Dilute Chemical Decontamination process could dissolve only 60% of the oxide. • Oxidation-Reduction process dissolves 100% oxide layer but time consuming. • High Temperature process is 100% efficient and less time consuming.

  5. Effects of O{sup 7+} swift heavy ion irradiation on indium oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Gokulakrishnan, V. [Crystal Growth and Thin Film Laboratory, School of Physics, Bharathidasan University, Tiruchirappalli 620024 (India); Parthiban, S. [Crystal Growth and Thin Film Laboratory, School of Physics, Bharathidasan University, Tiruchirappalli 620024 (India); CENIMAT-I3N and CEMOP-UNINOVA, Materials Science Department, FCT-UNL, Caparica Campus, 2829-516 Caparica (Portugal); Elangovan, E. [CENIMAT-I3N and CEMOP-UNINOVA, Materials Science Department, FCT-UNL, Caparica Campus, 2829-516 Caparica (Portugal); Ramamurthi, K., E-mail: krmurthin@yahoo.co.in [Crystal Growth and Thin Film Laboratory, School of Physics, Bharathidasan University, Tiruchirappalli 620024 (India); Jeganathan, K. [Centre for Nanoscience and Nanotechnology, School of Physics, Bharathidasan University, Tiruchirappalli 620024 (India); Kanjilal, D.; Asokan, K. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Martins, R.; Fortunato, E. [CENIMAT-I3N and CEMOP-UNINOVA, Materials Science Department, FCT-UNL, Caparica Campus, 2829-516 Caparica (Portugal)

    2011-08-15

    Highlights: {yields} The structural, morphology and electrical properties of indium oxide thin films. {yields} From the XRD, the ion irradiation has changed the preferred orientation from (2 2 2) to (4 0 0). {yields} RMS roughness is significantly reduced to 10 nm for an ion fluency of 1 x 10{sup 13} ions/cm{sup 2}. {yields} The mobility of ion irradiated films (1 x 10{sup 13} ions/cm{sup 2}) is decreased from 76.6 to 43 cm{sup 2}/V s. {yields} The average transmittance (400-2500 nm) of the as-deposited IO film is decreased from 81% to 72% after SHI irradiation. - Abstract: Indium oxide thin films deposited by spray pyrolysis were irradiated by 100 MeV O{sup 7+} ions with different fluences of 5 x 10{sup 11}, 1 x 10{sup 12} and 1 x 10{sup 13} ions/cm{sup 2}. X-ray diffraction analysis confirmed the structure of indium oxide with cubic bixbyite. The strongest (2 2 2) orientation observed from the as-deposited films was shifted to (4 0 0) after irradiation. Furthermore, the intensity of the (4 0 0) orientation was decreased with increasing fluence together with an increase in (2 2 2) intensity. Films irradiated with maximum fluence exhibited an amorphous component. The mobility of the as-deposited indium oxide films was decreased from {approx}78.9 to 43.0 cm{sup 2}/V s, following irradiation. Films irradiated with a fluence of 5 x 10{sup 11} ions/cm{sup 2} showed a better combination of electrical properties, with a resistivity of 4.57 x 10{sup -3} {Omega} cm, carrier concentration of 2.2 x 10{sup 19} cm{sup -3} and mobility of 61.0 cm{sup 2}/V s. The average transmittance obtained from the as-deposited films decreased from {approx}81% to 72%, when irradiated with a fluence of 5 x 10{sup 11} ions/cm{sup 2}. The surface microstructures confirmed that the irregularly shaped grains seen on the surface of the as-deposited films is modified as 'radish-like' morphology when irradiated with a fluence of 5 x 10{sup 11} ions/cm{sup 2}.

  6. Demonstration of high-performance p-type tin oxide thin-film transistors using argon-plasma surface treatments

    Science.gov (United States)

    Bae, Sang-Dae; Kwon, Soo-Hun; Jeong, Hwan-Seok; Kwon, Hyuck-In

    2017-07-01

    In this work, we investigated the effects of low-temperature argon (Ar)-plasma surface treatments on the physical and chemical structures of p-type tin oxide thin-films and the electrical performance of p-type tin oxide thin-film transistors (TFTs). From the x-ray photoelectron spectroscopy measurement, we found that SnO was the dominant phase in the deposited tin oxide thin-film, and the Ar-plasma treatment partially transformed the tin oxide phase from SnO to SnO2 by oxidation. The resistivity of the tin oxide thin-film increased with the plasma-treatment time because of the reduced hole concentration. In addition, the root-mean-square roughness of the tin oxide thin-film decreased as the plasma-treatment time increased. The p-type oxide TFT with an Ar-plasma-treated tin oxide thin-film exhibited excellent electrical performance with a high current on-off ratio (5.2 × 106) and a low off-current (1.2 × 10-12 A), which demonstrates that the low-temperature Ar-plasma treatment is a simple and effective method for improving the electrical performance of p-type tin oxide TFTs.

  7. Strain-Induced Water Dissociation on Supported Ultrathin Oxide Films

    CERN Document Server

    Song, Zhenjun; Xu, Hu

    2015-01-01

    Controlling the dissociation of single water molecule on an insulating surface plays a crucial role in many catalytic reactions. In this Letter, we have identified the enhanced chemical reactivity of ultrathin MgO(100) films deposited on Mo(100) substrate that causes water dissociation. We reveal that the ability to split water on insulating surface closely depends on the lattice mismatch between ultrathin films and the underlying substrate, and substrate-induced in-plane tensile strain dramatically results in water dissociation on MgO(100). Three dissociative adsorption configurations of water with lower energy are predicted, and the structural transition going from molecular form to dissociative form is almost barrierless. Our results provide an effective avenue to achieve water dissociation at the single-molecule level and shed light on how to tune the chemical reactions of insulating surfaces by choosing the suitable substrates.

  8. Development of Doped Microcrystalline Silicon Oxide and its Application to Thin‑Film Silicon Solar Cells

    NARCIS (Netherlands)

    Lambertz, A.

    2015-01-01

    The aim of the present study is the development of doped microcrystalline silicon oxide (µc‑SiOx:H) alloys and its application in thin‑film silicon solar cells. The doped µc‑SiOx:H material was prepared from carbon dioxide (CO2), silane (SiH4), hydrogen (H2) gas mixtures using plasma enhanced

  9. Growth Process Conditions of Tungsten Oxide Thin Films Using Hot-Wire Chemical Vapor Deposition

    NARCIS (Netherlands)

    Houweling, Z.S.|info:eu-repo/dai/nl/251874486; Geus, J.W.; de Jong, M.; Harks, P.P.R.M.L.; van der Werf, C.H.M.; Schropp, R.E.I.|info:eu-repo/dai/nl/072502584

    2011-01-01

    We report the growth conditions of nanostructured tungsten oxide (WO3−x) thin films using hot-wire chemical vapor deposition (HWCVD). Two tungsten filaments were resistively heated to various temperatures and exposed to an air flow at various subatmospheric pressures. The oxygen partial pressure was

  10. Mossbauer investigations of corrosion environment influence on Fe valence states in oxide films of zirconium alloys

    NARCIS (Netherlands)

    Filippov, V. P.; Petrov, V. I.; Shikanova, Yu. A.

    2006-01-01

    Mossbauer investigations about iron atom redistribution in oxide films of zirconium alloys subjected to corrosion at 500 degrees C in pure oxygen and water pair have been analysed. The alloys were also subjected to autoclave conditions at a pressure of 10.0 MPa and autoclave conditions at 350

  11. The Effect of Anodic Oxide Films on the Nickel-Aluminum Reaction in Aluminum Braze Sheet

    Science.gov (United States)

    Tadgell, Colin A.; Wells, Mary A.; Corbin, Stephen F.; Colley, Leo; Cheadle, Brian; Winkler, Sooky

    2017-03-01

    The influence of an anodic oxide surface film on the nickel-aluminum reaction at the surface of aluminum brazing sheet has been investigated. Samples were anodized in a barrier-type solution and subsequently sputtered with nickel. Differential scanning calorimetry (DSC) and metallography were used as the main investigative techniques. The thickness of the anodic film was found to control the reaction between the aluminum substrate and nickel coating. Solid-state formation of nickel-aluminum intermetallic phases occurred readily when a relatively thin oxide film (13 to 25 nm) was present, whereas intermetallic formation was suppressed in the presence of thicker oxides ( 60 nm). At an intermediate oxide film thickness of 35 nm, the Al3Ni phase formed shortly after the initiation of melting in the aluminum substrate. Analysis of DSC traces showed that formation of nickel-aluminum intermetallic phases changed the melting characteristics of the aluminum substrate, and that the extent of this change can be used as an indirect measure of the amount of nickel incorporated into the intermetallic phases.

  12. FIB-SEM investigation of trapped intermetallic particles in anodic oxide films on AA1050 aluminium

    DEFF Research Database (Denmark)

    Jariyaboon, Manthana; Møller, Per; Dunin-Borkowski, Rafal E.

    2011-01-01

    Purpose - The purpose of this investigation is to understand the structure of trapped intermetallics particles and localized composition changes in the anodized anodic oxide film on AA1050 aluminium substrates. Design/methodology/approach - The morphology and composition of Fe-containing intermet...

  13. Spectroscopic studies of electron injection in quantum dot sensitized mesoporous oxide films

    NARCIS (Netherlands)

    Pijpers, J. J. H.; Koole, R.|info:eu-repo/dai/nl/298205610; Evers, W.H.|info:eu-repo/dai/nl/315553146; Houtepen, A.J.; Boehme, S.; de Mello Donega, C.|info:eu-repo/dai/nl/125593899; Vanmaekelbergh, D.A.M.|info:eu-repo/dai/nl/304829137; Bonn, M.

    2010-01-01

    Optimization of interfacial charge transfer in quantum dot (QD) sensitized mesoporous oxide films is crucial for the efficient design of QD sensitized solar cells (QDSSC). We employ TeraHertz time-domain spectroscopy (THz-TDS), transient absorption (TA) and time-resolved luminescence measurements,

  14. Electrophoretic deposition of semiconducting polymer metal oxide nanocomposites and characterization of the resulting films

    OpenAIRE

    Vu, Quoc Trung

    2005-01-01

    Conducting polymer nanocomposites composed of metal oxides and polythiophene was synthesized by chemical polymerization in colloidal suspensions. The electrochemical and photoelectrochemical properties of such nanocomposites have been studied. For these investigations films of nanocomposites were prepared by an electrophoretic deposition process. The deposition process was studied in greater detail and kinetic details were determined. The high voltage electrophoretic deposition process was co...

  15. Nitric oxide-generating l-cysteine-grafted graphene film as a blood-contacting biomaterial.

    Science.gov (United States)

    Du, Zhen; Dou, Ruixia; Zu, Mian; Liu, Xueying; Yin, Wenyan; Zhao, Yuliang; Chen, Jingbo; Yan, Liang; Gu, Zhanjun

    2016-06-24

    By using polyethylenimine molecules as the linker, l-cysteine was immobilized onto graphene nanosheets, endowing the biocompatible l-cysteine-functionalized graphene film with the ability for catalytic decomposition of exogenous or endogenous donors to generate nitric oxide, and thus inhibiting the platelet activation and aggregation and reducing platelet adhesion.

  16. Flexible metal-oxide thin film transistor circuits for RFID and health patches

    NARCIS (Netherlands)

    Heremans, P.; Papadopoulos, N.; Jamblinne De Meux, A. de; Nag, M.; Steudel, S.; Rockele, M.; Gelinck, G.; Tripathi, A.; Genoe, J.; Myny, K.

    2016-01-01

    We discuss in this paper the present state and future perspectives of thin-film oxide transistors for flexible electronics. The application case that we focus on is a flexible health patch containing an analog sensor interface as well as digital electronics to transmit the acquired data wirelessly

  17. Localized tail state distribution and hopping transport in ultrathin zinc-tin-oxide thin film transistor

    NARCIS (Netherlands)

    Li, Jeng-Ting; Liu, Li-Chih; Chen, Jen-Sue; Jeng, Jiann-Shing; Liao, Po-Yung; Chiang, Hsiao-Cheng; Chang, Ting-Chang; Nugraha, Mohamad Insan; Loi, Maria Antonietta

    2017-01-01

    Carrier transport properties of solution processed ultra thin (4 nm) zinc-tin oxide (ZTO) thin film transistor are investigated based on its transfer characteristics measured at the temperature ranging from 310K to 77K. As temperature decreases, the transfer curves show a parellel shift toward more

  18. Drop-photochemical deposition of aluminum oxide thin films from aqueous solutions

    Science.gov (United States)

    Sato, Shunta; Ichimura, Masaya

    2017-04-01

    Aluminum oxide thin films were deposited onto fluorine-doped tin oxide-coated glass by drop photochemical deposition for the first time. The deposition solution was deionized water containing aluminum sulfate and sodium thiosulfate. Small amount of the solution was dropped on the substrate and irradiated with UV light. The solution was replaced with new one after 5 min irradiation, and the process was repeated 10 times. A film was not deposited without thiosulfate ions in the solution. The deposited films were transparent, and their band gap was larger than 4 eV. The O/Al composition ratio was about 1.2, smaller than the stoichiometric ratio 1.5.

  19. X-ray absorption spectroscopy studies of electrochemically deposited thin oxide films.

    Energy Technology Data Exchange (ETDEWEB)

    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.

  20. Controllable SERS performance for the flexible paper-like films of reduced graphene oxide

    Science.gov (United States)

    Yan, Taotao; Zhang, Lili; Jiang, Tongtong; Bai, Zhiman; Yu, Xinxin; Dai, Peng; Wu, Mingzai

    2017-10-01

    paper-like films of reduced graphene oxide with controllable shapes and thickness were prepared via funnel filtration and thermal reduction of graphene oxide (GO), which could work as flexible surface-enhanced Raman scattering (SERS) substrates to detect Rhodamine 6G (R6G) molecules. The SERS signal intensity of R6G on annealed films was found to be related with the annealling temperature. The most intense signal was observed for the film obtained at 800 °C. While for the sample annealed at 1000 °C, no SERS signal could be detected. The underlying mechanism for the difference was discussed. The reported preparation process of flexible rGO paper is simple and cost-effective, which shows great potential in rapid biochemical analysis of agricultural products with irregular surfaces.

  1. Localized Control of Curie Temperature in Perovskite Oxide Film by Capping-Layer-Induced Octahedral Distortion

    Science.gov (United States)

    Thomas, S.; Kuiper, B.; Hu, J.; Smit, J.; Liao, Z.; Zhong, Z.; Rijnders, G.; Vailionis, A.; Wu, R.; Koster, G.; Xia, J.

    2017-10-01

    With reduced dimensionality, it is often easier to modify the properties of ultrathin films than their bulk counterparts. Strain engineering, usually achieved by choosing appropriate substrates, has been proven effective in controlling the properties of perovskite oxide films. An emerging alternative route for developing new multifunctional perovskite is by modification of the oxygen octahedral structure. Here we report the control of structural oxygen octahedral rotation in ultrathin perovskite SrRuO3 films by the deposition of a SrTiO3 capping layer, which can be lithographically patterned to achieve local control. Using a scanning Sagnac magnetic microscope, we show an increase in the Curie temperature of SrRuO3 due to the suppression octahedral rotations revealed by the synchrotron x-ray diffraction. This capping-layer-based technique may open new possibilities for developing functional oxide materials.

  2. Super high sensitive plate acoustic wave humidity sensor based on graphene oxide film.

    Science.gov (United States)

    Kuznetsova, Iren E; Anisimkin, Vladimir I; Gubin, Sergei P; Tkachev, Sergei V; Kolesov, Vladimir V; Kashin, Vadim V; Zaitsev, Boris D; Shikhabudinov, Alexander M; Verona, Enrico; Sun, Shaorong

    2017-11-01

    The changes of density and elastic modules due to water vapor adsorption are measured for graphene oxide film at room temperature. Dominant mechanism for acoustic wave humidity sensing by the film is shown to be related with variation of its electric conductivity. Basing on the data, super high sensitive humidity sensor employing high-order Lamb wave with large coupling constant, standard lithium niobate plate, and graphene oxide sorbent film is developed. The minimal detectable level of the sensor is as low 0.03% RH, response times are 60/120s, and reproducibility is ±2.5%. The sensor is completely selective towards H2, CO, CH4, NO, O2. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Chemical solution deposited lanthanum zirconium oxide thin films: Synthesis and chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Chen, H.S., E-mail: sean.chen@cantab.net [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom); Kumar, R.V.; Glowacki, B.A. [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom)

    2010-07-01

    Pyrochlore lanthanum zirconium oxide (LZO) thin films textured along <4 0 0> are synthesized using lanthanum acetate hydrate, zirconium propoxide, propionic acid, acetic acid glacial, and methanol as precursors. The materials growth and chemistry are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and thermal gravimetric analysis (TGA). The formation of inkjet printed LZO films on Ni-5%W tape is found to be based on the decomposition of the LZO precursor solution. In the annealing process, Zr metal-oxides bonds are first eliminated between 150 and 250 deg. C, while carboxylates from precursors remain in LZO after the annealing carried out at 900 {sup o}C for an hour. Annealed LZO films have dense and smooth structure that are composed of nanoparticles sizing 10-15 nm and some pinholes sizing 25-35 nm accounted for less than 0.1% of the area are observed.

  4. Heterojunction Solar Cells Based on Silicon and Composite Films of Graphene Oxide and Carbon Nanotubes.

    Science.gov (United States)

    Yu, LePing; Tune, Daniel; Shearer, Cameron; Shapter, Joseph

    2015-09-07

    Graphene oxide (GO) sheets have been used as the surfactant to disperse single-walled carbon nanotubes (CNT) in water to prepare GO/CNT electrodes that are applied to silicon to form a heterojunction that can be used in solar cells. GO/CNT films with different ratios of the two components and with various thicknesses have been used as semitransparent electrodes, and the influence of both factors on the performance of the solar cell has been studied. The degradation rate of the GO/CNT-silicon devices under ambient conditions has also been explored. The influence of the film thickness on the device performance is related to the interplay of two competing factors, namely, sheet resistance and transmittance. CNTs help to improve the conductivity of the GO/CNT film, and GO is able to protect the silicon from oxidation in the atmosphere. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. High Mobility Thin Film Transistors Based on Amorphous Indium Zinc Tin Oxide.

    Science.gov (United States)

    Noviyana, Imas; Lestari, Annisa Dwi; Putri, Maryane; Won, Mi-Sook; Bae, Jong-Seong; Heo, Young-Woo; Lee, Hee Young

    2017-06-26

    Top-contact bottom-gate thin film transistors (TFTs) with zinc-rich indium zinc tin oxide (IZTO) active layer were prepared at room temperature by radio frequency magnetron sputtering. Sintered ceramic target was prepared and used for deposition from oxide powder mixture having the molar ratio of In2O3:ZnO:SnO2 = 2:5:1. Annealing treatment was carried out for as-deposited films at various temperatures to investigate its effect on TFT performances. It was found that annealing treatment at 350 °C for 30 min in air atmosphere yielded the best result, with the high field effect mobility value of 34 cm2/Vs and the minimum subthreshold swing value of 0.12 V/dec. All IZTO thin films were amorphous, even after annealing treatment of up to 350 °C.

  6. Characterization of monolayer formation on aluminum-doped zinc oxide thin films.

    Science.gov (United States)

    Rhodes, Crissy L; Lappi, Simon; Fischer, Daniel; Sambasivan, Sharadha; Genzer, Jan; Franzen, Stefan

    2008-01-15

    The optical and electronic properties of aluminum-doped zinc oxide (AZO) thin films on a glass substrate are investigated experimentally and theoretically. Optical studies with coupling in the Kretschmann configuration reveal an angle-dependent plasma frequency in the mid-IR for p-polarized radiation, suggestive of the detection of a Drude plasma frequency. These studies are complemented by oxygen depletion density functional theory studies for the calculation of the charge carrier concentration and plasma frequency for bulk AZO. In addition, we report on the optical and physical properties of thin film adlayers of n-hexadecanethiol (HDT) and n-octadecanethiol (ODT) self-assembled monolayers (SAMs) on AZO surfaces using reflectance FTIR spectroscopy, X-ray photoelectron spectroscopy (XPS), contact angle, and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. Our characterization of the SAM deposition onto the AZO thin film reveals a range of possible applications for this conducting metal oxide.

  7. High Mobility Thin Film Transistors Based on Amorphous Indium Zinc Tin Oxide

    Directory of Open Access Journals (Sweden)

    Imas Noviyana

    2017-06-01

    Full Text Available Top-contact bottom-gate thin film transistors (TFTs with zinc-rich indium zinc tin oxide (IZTO active layer were prepared at room temperature by radio frequency magnetron sputtering. Sintered ceramic target was prepared and used for deposition from oxide powder mixture having the molar ratio of In2O3:ZnO:SnO2 = 2:5:1. Annealing treatment was carried out for as-deposited films at various temperatures to investigate its effect on TFT performances. It was found that annealing treatment at 350 °C for 30 min in air atmosphere yielded the best result, with the high field effect mobility value of 34 cm2/Vs and the minimum subthreshold swing value of 0.12 V/dec. All IZTO thin films were amorphous, even after annealing treatment of up to 350 °C.

  8. Solution-Processed Flexible Fluorine-doped Indium Zinc Oxide Thin-Film Transistors Fabricated on Plastic Film at Low Temperature

    OpenAIRE

    Jin-Suk Seo; Jun-Hyuck Jeon; Young Hwan Hwang; Hyungjin Park; Minki Ryu; Sang-Hee Ko Park; Byeong-Soo Bae

    2013-01-01

    Transparent flexible fluorine-doped indium zinc oxide (IZO:F) thin-film transistors (TFTs) were demonstrated using the spin-coating method of the metal fluoride precursor aqueous solution with annealing at 200?C for 2?hrs on polyethylene naphthalate films. The proposed thermal evolution mechanism of metal fluoride aqueous precursor solution examined by thermogravimetric analysis and Raman spectroscopy can easily explain oxide formation. The chemical composition analysed by XPS confirms that t...

  9. Drying of films formed by ordered poly(ethylene oxide)-poly(propylene oxide) block copolymer gels.

    Science.gov (United States)

    Gu, Zhiyong; Alexandridis, Paschalis

    2005-03-01

    The drying of hydrogel films formed by poly(ethylene oxide)-poly(propylene oxide) (PEO-PPO) block copolymers (Pluronic P105 and Pluronic L64) is investigated at various air relative humidity (RH) conditions in the range 11-94%. These amphiphilic block copolymers self-assemble to form a variety of ordered (lyotropic liquid crystalline) structures as the water content decreases. The amount of water lost increases linearly with the drying time initially (constant rate region, stage I). After this linear region, a falling rate is observed (stage II). The drying rate increases with decreasing RH, thus greatly shortening the drying time. A decrease of the initial film thickness or a decrease in the initial water content shortens the drying time; however, the drying mechanism remains the same. Analysis of the experimental data shows that the hydration level in the Pluronic hydrogel mainly determines the drying rate, rather than the type of ordered structure formed. Two distinct regions (liquid/gel and solid/crystalline) are observed in the drying isotherm for PEO-PPO block copolymers and homopolymer poly(ethylene glycol)s. A model for one-dimensional water diffusion is used to fit the experimental drying results at different RH, initial film thickness, and initial water content conditions. The model accounts for the shrinkage of the film during drying and for a water diffusion coefficient that is a function of the water concentration in the film. For the experimental conditions considered here, the Biot number (Bi) is less than unity and the drying is mainly limited by evaporation at the film surface. The diffusion model is used to obtain information for cases where Bi > 1.

  10. On the possibility to grow zinc oxide-based transparent conducting oxide films by hot-wire chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Abrutis, Adulfas, E-mail: adulfas.abrutis@chf.vu.lt; Silimavicus, Laimis; Kubilius, Virgaudas; Murauskas, Tomas; Saltyte, Zita; Kuprenaite, Sabina; Plausinaitiene, Valentina [Faculty of Chemistry, Vilnius University, Naugarduko 24, LT-03225 Vilnius (Lithuania)

    2014-03-15

    Hot-wire chemical vapor deposition (HW-CVD) was applied to grow zinc oxide (ZnO)-based transparent conducting oxide (TCO) films. Indium (In)-doped ZnO films were deposited using a cold wall pulsed liquid injection CVD system with three nichrome wires installed at a distance of 2 cm from the substrate holder. The wires were heated by an AC current in the range of 0–10 A. Zn and In 2,2,6,6-tetramethyl-3,5-heptanedionates dissolved in 1,2-dimethoxyethane were used as precursors. The hot wires had a marked effect on the growth rates of ZnO, In-doped ZnO, and In{sub 2}O{sub 3} films; at a current of 6–10 A, growth rates were increased by a factor of ≈10–20 compared with those of traditional CVD at the same substrate temperature (400 °C). In-doped ZnO films with thickness of ≈150 nm deposited on sapphire-R grown at a wire current of 9 A exhibited a resistivity of ≈2 × 10{sup −3} Ωcm and transparency of >90% in the visible spectral range. These initial results reveal the potential of HW-CVD for the growth of TCOs.

  11. Design and fabrication of hafnium tube to control the power of the irradiation test fuel in HANARO

    Energy Technology Data Exchange (ETDEWEB)

    Kim, D. H.; Lee, C. B.; Kim, Y. M.; Yang, Y. S.; Jung, Y. H

    2003-05-01

    For the irradiation test at HANARO, non-instrumentation capsule was manufactured and hafnium tube was used to control LHGR of HANARO. Hafnium tube can control the irradiation condition of HANARO similar to that of commercial reactor. Hafnium tube thickness was determined by the LHGR calculated at OR-4 irradiation hole to be installed the non-instrumented capsule. To fabricate the hafnium tube with hafnium plate, the fabrication method was determined by using the hafnium mechanical properties. And the tensile strength of hafnium was confirmed by tensile test. This report is confirmed the LHGR control at the OR-4 and the Hafnium fabrication for in used which the AFPCAP non-instrumented irradiation capsule.

  12. Study of Interfacial Interactions Using Thing Film Surface Modification: Radiation and Oxidation Effects in Materials

    Energy Technology Data Exchange (ETDEWEB)

    Sridharan, Kumar; Zhang, Jinsuo

    2014-01-09

    Interfaces play a key role in dictating the long-term stability of materials under the influence of radiation and high temperatures. For example, grain boundaries affect corrosion by way of providing kinetically favorable paths for elemental diffusion, but they can also act as sinks for defects and helium generated during irradiation. Likewise, the retention of high-temperature strength in nanostructured, oxide-dispersion strengthened steels depends strongly on the stoichiometric and physical stability of the (Y, Ti)-oxide particles/matrix interface under radiation and high temperatures. An understanding of these interfacial effects at a fundamental level is important for the development of materials for extreme environments of nuclear reactors. The goal of this project is to develop an understanding stability of interfaces by depositing thin films of materials on substrates followed by ion irradiation of the film-substrate system at elevated temperatures followed by post-irradiation oxidation treatments. Specifically, the research will be performed by depositing thin films of yttrium and titanium (~500 nm) on Fe-12%Cr binary alloy substrate. Y and Ti have been selected as thin-film materials because they form highly stable protective oxides layers. The Fe-12%Cr binary alloy has been selected because it is representative of ferritic steels that are widely used in nuclear systems. The absence of other alloying elements in this binary alloy would allow for a clearer examination of structures and compositions that evolve during high-temperature irradiations and oxidation treatments. The research is divided into four specific tasks: (1) sputter deposition of 500 nm thick films of Y and Ti on Fe-12%Cr alloy substrates, (2) ion irradiation of the film-substrate system with 2MeV protons to a dose of 2 dpa at temperatures of 300°C, 500°C, and 700°C, (3) oxidation of as-deposited and ion-irradiated samples in a controlled oxygen environment at 500°C and 700°C, (4

  13. Fabrication and properties of nanocrystalline zinc oxide thin film prepared by sol-gel method

    Directory of Open Access Journals (Sweden)

    Sumetha Suwanboon

    2008-01-01

    Full Text Available Zinc oxide (ZnO thin films were prepared on glass substrate by sol-gel dip-coating method. The structural properties were investigated by x-ray diffraction (XRD method and atomic force microscope (AFM. The optical properties were measured by UV-Vis spectrophotometer. The XRD patterns showed that the films formed preferred orientation along c-axis which increased as a function of polyvinyl pyrrolidone (PVP concentration. The films gave the crystallite size of 15-18 nm calculated by Scherrer’s formula and grain size of 48-70 nm measured by AFM at different PVP concentrations. The direct optical band gap of the films was in the range of 3.80-4.08 eV.

  14. Extraordinary suppression of carrier scattering in large area graphene oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Negishi, R., E-mail: negishi@ap.eng.osaka-u.ac.jp; Kobayashi, Y. [Department of Applied Physics, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)

    2014-12-22

    In this study, we find that thermal treatment in ethanol vapor has a remarkable suppression effect of carrier scattering occurring between reduced graphene oxide (rGO) flakes in large area films. We observe excellent electrical properties such as high carrier mobility (∼5 cm{sup 2}/Vs) and low sheet resistance (∼40 KΩ/□) for the rGO films. From the electrical conductivity analysis of large area rGO films using two-dimensional variable range hopping model and structural analysis using Raman spectra measured from the rGO films, we reveal that the significant effect is caused by the expansion of conjugated π-electron system in rGO flake due to the efficient restoration of graphitic structure.

  15. Electric field assisted thermal annealing reorganization of graphene oxide/polystyrene latex films

    Directory of Open Access Journals (Sweden)

    2011-09-01

    Full Text Available Graphene/polymer films were prepared by casting water dispersion of graphene oxide (GO in the presence of polystyrene (PS latex particles. The samples were heated up to 180°C and exposed to an external electric voltage during their annealing. We observed that for the GO/PS films deposited before the electric field assisted thermal annealing the polymer latex was embedded in the graphene sheets, while the electric field assisted thermal annealing induces a phase separation with the enrichment of the PS phase above an underlying GO layer. For the films annealed under an external electric field we have also found that as the electric current passes through the GO film, GO could be recovered to reduced GO with decreased resistance.

  16. Preparation and characterization of tantalum oxide films produced by reactive DC magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Ngaruiya, J.M. [I. Physikalisches Institut der RWTH Aachen, 52056 Aachen (Germany); Jomo Kenyatta University of Agric. and Techn., Box 62000, Nairobi (Kenya); Venkataraj, S.; Drese, R.; Kappertz, O.; Leervad Pedersen, T.P. [I. Physikalisches Institut der RWTH Aachen, 52056 Aachen (Germany); Wuttig, M. [I. Physikalisches Institut der RWTH Aachen, 52056 Aachen (Germany); ISG3, Forschungszentrum Juelich, 52428 Juelich (Germany)

    2003-07-01

    We report on the influence of oxygen flow rate on structure, composition, density, deposition stress and optical properties of the as-deposited tantalum oxide thin films. The films were prepared by reactive direct current magnetron sputtering. The sputter current and total pressure were kept constant at 300 mA and 0.8 Pa, respectively. We could deposit fully transparent films at a rate of approximately 6 nm/min. without noticeable substrate warming from the plasma. Grazing angle XRD showed the films to be amorphous at all oxygen flow rates. Simulations to RBS data revealed, within errors, stoichiometric films above 2 sccm oxygen flow. Moreover argon incorporation in the films above 2 sccm oxygen flow was noted. The density was found to steeply decrease upto 2 sccm followed by a very slow linear decrease with oxygen flow as deduced from X-ray reflectometry. The refractive index, the extinction coefficient and the band gap energy were all obtained by optical spectroscopy. A band gap which increased from 4.17 to 4.23 eV with oxygen flow was determined for films in the transparent region. A characteristic of the defects in the film, {gamma}, which is obtained by simulating the optical spectra, was found to decrease from 85 meV at 6 sccm to 60 meV at 15 sccm oxygen flow. There was no significant change in {gamma} above 15 sccm. On the other hand the refractive index and the extinction coefficient were found to slightly decrease with increasing oxygen flow for the transparent films. Stress data revealed the films to be under some compressive stress upon deposition. The stress decreased with increasing oxygen flow and stabilized at roughly -250 MPa above 6 sccm oxygen flow. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  17. Facile synthesis of cobalt-doped zinc oxide thin films for highly efficient visible light photocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Altintas Yildirim, Ozlem, E-mail: ozlemaltintas@gmail.com [Department of Metallurgical and Materials Engineering, Selcuk University, Konya (Turkey); Arslan, Hanife; Sönmezoğlu, Savaş [Department of Metallurgical and Materials Engineering, Karamanoglu Mehmetbey University, Karaman (Turkey); Nanotechnology R& D Laboratory, Karamanoglu Mehmetbey University, Karaman (Turkey)

    2016-12-30

    Highlights: • Photocatalytically active Co-ZnO thin film was obtained by sol-gel method. • Co{sup 2+} doping narrowed the band gap of pure ZnO to an extent of 3.18 eV. • Co-ZnO was effective in MB degradation under visible light. • Optimum dopant content to show high performance was 3 at.%. - Abstract: 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). Co{sup 2+} ions were observed to be substitutionally incorporated into Zn{sup 2+} 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.

  18. Transparent semiconducting amorphous cadmium-gallium-tin oxide films by magnetron sputtering with water vapor

    Science.gov (United States)

    Yanagi, Hiroshi; Koyamaishi, Yusuke; Sato, Chiyuki; Kimura, Yota

    2017-06-01

    Amorphous oxide semiconductors (including transparent ones) are attractive materials for next-generation optoelectronic applications. One of the difficulties with amorphous oxide semiconductors is the lack of high mobility (>10 cm2 V-1 s-1) at low carrier density (radio-frequency magnetron sputtering with a water-vapor pressure ≥0.25 Pa. In these amorphous films, the threshold carrier density for obtaining high mobility (˜10 cm2 V-1 s-1) is possibly four orders of magnitude lower than that in conventional amorphous oxide semiconductors such as amorphous In-Ga-Zn-O.

  19. UV protective zinc oxide coating for biaxially oriented polypropylene packaging film by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lahtinen, Kimmo, E-mail: kimmo.lahtinen@lut.fi [ASTRaL, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli (Finland); Kääriäinen, Tommi, E-mail: tommi.kaariainen@colorado.edu [ASTRaL, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli (Finland); Johansson, Petri, E-mail: petri.johansson@tut.fi [Paper Converting and Packaging Technology, Tampere University of Technology, P.O.Box 589, FI-33101 Tampere (Finland); Kotkamo, Sami, E-mail: sami.kotkamo@tut.fi [Paper Converting and Packaging Technology, Tampere University of Technology, P.O.Box 589, FI-33101 Tampere (Finland); Maydannik, Philipp, E-mail: philipp.maydannik@lut.fi [ASTRaL, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli (Finland); Seppänen, Tarja, E-mail: tarja.seppanen@lut.fi [ASTRaL, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli (Finland); Kuusipalo, Jurkka, E-mail: jurkka.kuusipalo@tut.fi [Paper Converting and Packaging Technology, Tampere University of Technology, P.O.Box 589, FI-33101 Tampere (Finland); Cameron, David C., E-mail: david.cameron@miktech.fi [ASTRaL, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli (Finland)

    2014-11-03

    Biaxially oriented polypropylene (BOPP) packaging film was coated with zinc oxide (ZnO) coatings by atomic layer deposition (ALD) in order to protect the film from UV degradation. The coatings were made at a process temperature of 100 °C using diethylzinc and water as zinc and oxygen precursors, respectively. The UV protective properties of the coatings were tested by using UV–VIS and infrared spectrometry, differential scanning calorimetry (DSC) and a mechanical strength tester, which characterised the tensile and elastic properties of the film. The results obtained with 36 and 67 nm ZnO coatings showed that the ZnO UV protective layer is able to provide a significant decrease in photodegradation of the BOPP film under UV exposure. While the uncoated BOPP film suffered a complete degradation after a 4-week UV exposure, the 67 nm ZnO coated BOPP film was able to preserve half of its original tensile strength and 1/3 of its elongation at break after a 6-week exposure period. The infrared analysis and DSC measurements further proved the UV protection of the ZnO coatings. The results show that a nanometre scale ZnO coating deposited by ALD is a promising option when a transparent UV protection layer is sought for polymer substrates. - Highlights: • Atomic layer deposited zinc oxide coatings were used as UV protection layers. • Biaxially oriented polypropylene (BOPP) film was well protected against UV light. • Formation of UV degradation products in BOPP was significantly reduced. • Mechanical properties of the UV exposed BOPP film were significantly improved.

  20. The Effect of Annealing on Nanothick Indium Tin Oxide Transparent Conductive Films for Touch Sensors

    Directory of Open Access Journals (Sweden)

    Shih-Hao Chan

    2015-01-01

    Full Text Available This study aims to discuss the sheet resistance of ultrathin indium tin oxide (ITO transparent conductive films during the postannealing treatment. The thickness of the ultrathin ITO films is 20 nm. They are prepared on B270 glass substrates at room temperature by a direct-current pulsed magnetron sputtering system. Ultrathin ITO films with high sheet resistance are commonly used for touch panel applications. As the annealing temperature is increased, the structure of the ultrathin ITO film changes from amorphous to polycrystalline. The crystalline of ultrathin ITO films becomes stronger with an increase of annealing temperature, which further leads to the effect of enhanced Hall mobility. A postannealing treatment in an atmosphere can enhance the optical transmittance owing to the filling of oxygen vacancies, but the sheet resistance rises sharply. However, a higher annealing temperature, above 250°C, results in a decrease in the sheet resistance of ultrathin ITO films, because more Sn ions become an effective dopant. An optimum sheet resistance of 336 Ω/sqr was obtained for ultrathin ITO films at 400°C with an average optical transmittance of 86.8% for touch sensor applications.

  1. Structure evolution of zinc oxide thin films deposited by unbalance DC magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Aryanto, Didik, E-mail: didi027@lipi.go.id [Research Center for Physics, Indonesian Institute of Sciences, Serpong 15314, Tangerang Selatan (Indonesia); Materials Research Group, Physics Department, Universitas Negeri Semarang, Gunungpati, Semarang 50229 Jawa Tengah (Indonesia); Marwoto, Putut; Sugianto [Physics Department, Faculty of Mathematics and Science, Universitas Negeri Semarang, Gunungpati, Semarang 50229 Jawa Tengah (Indonesia); Materials Research Group, Physics Department, Universitas Negeri Semarang, Gunungpati, Semarang 50229 Jawa Tengah (Indonesia); Sudiro, Toto [Research Center for Physics, Indonesian Institute of Sciences, Serpong 15314, Tangerang Selatan (Indonesia); Birowosuto, Muhammad D. [Research Center for Physics, Indonesian Institute of Sciences, Serpong 15314, Tangerang Selatan (Indonesia); CINTRA UMI CNRS/NTU/THALES 3288 Research Techno Plaza, 50 Nanyang Drive, Border X Block, level 6, 637553 (Singapore); Sulhadi [Physics Department, Faculty of Mathematics and Science, Universitas Negeri Semarang, Gunungpati, Semarang 50229 Jawa Tengah (Indonesia)

    2016-04-19

    Zinc oxide (ZnO) thin films are deposited on corning glass substrates using unbalanced DC magnetron sputtering. The effect of growth temperature on surface morphology and crystallographic orientation of ZnO thin film is studied using atomic force microscopy (AFM) and X-ray diffraction (XRD) techniques. The surface morphology and crystallographic orientation of ZnO thin film are transformed against the increasing of growth temperature. The mean grain size of film and the surface roughness are inversely and directly proportional towards the growth temperature from room temperature to 300 °C, respectively. The smaller grain size and finer roughness of ZnO thin film are obtained at growth temperature of 400 °C. The result of AFM analysis is in good agreement with the result of XRD analysis. ZnO thin films deposited in a series of growth temperatures have hexagonal wurtzite polycrystalline structures and they exhibit transformations in the crystallographic orientation. The results in this study reveal that the growth temperature strongly influences the surface morphology and crystallographic orientation of ZnO thin film.

  2. Synthesis and characterization of zinc oxide thin films for optoelectronic applications.

    Science.gov (United States)

    Muchuweni, E; Sathiaraj, T S; Nyakotyo, H

    2017-04-01

    Micro-ring structured zinc oxide (ZnO) thin films were prepared on glass substrates by spray pyrolysis and their structural, morphological, optical and electrical properties were investigated. X-ray Diffraction (XRD) analysis revealed the films' hexagonal wurtzite phase with a preferred (002) grain orientation. The mean crystallite size calculated on the basis of the Debye-Scherrer model was 24 nm and a small dislocation density of [Formula: see text] was obtained, indicating the existence of few lattice defects and good crystallinity. Scanning Electron Microscopy (SEM) micrographs revealed the film's granular nature composed of rod-shaped and spherical nanoparticles which agglomerated to form micro-ring like film clusters on the film surface. The average transmittance in the visible region, optical band gap and Urbach energy were approximately 75-80%, 3.28 eV and 57 meV, respectively. The refractive index and extinction coefficient were determined using Swanepoel's envelope method. Raman spectroscopy revealed the presence of small amounts of residual tensile stress and low density of defects in the ZnO thin films. This was consistent with XRD analysis. A low sheet resistivity [Formula: see text] and high figure of merit [Formula: see text] were obtained for our films indicating their suitability in optoelectronic applications.

  3. Optical properties of tungsten oxide thin films by non-reactive sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Acosta, M., E-mail: milenis@yahoo.co [Laboratorio de Ciencia de Materiales, Facultad de Ingenieria, Universidad Autonoma de Yucatan, Avenida Industrias No Contaminantes S/N, A.P. 150, Cordemex, Merida (Mexico); Gonzalez, D.; Riech, I. [Laboratorio de Ciencia de Materiales, Facultad de Ingenieria, Universidad Autonoma de Yucatan, Avenida Industrias No Contaminantes S/N, A.P. 150, Cordemex, Merida (Mexico)

    2009-07-31

    Tungsten oxide thin films were grown on glass substrates by RF sputtering at room temperature using a tungsten trioxide target for several values of the argon pressure (P{sub Ar}). The structural and morphological properties of these films were studied using X-ray diffraction and atomic force microscopy. The as-deposited films were amorphous irrespective of the argon pressure, and crystallized in a mixture of hexagonal and monoclinic phases after annealing at a temperature of 350 {sup o}C in air. Surface-roughness increased by an order of magnitude (from 1 nm to 20 nm) after thermal treatment. The argon pressure, however, had a strong influence on the optical properties of the films. Three different regions are clearly identified: deep blue films for P{sub Ar} {<=} 2.67 Pa with low transmittance values, light blue films for 2.67 Pa < P{sub Ar} < 6 Pa with intermediate transmittance values and transparent films for P{sub Ar} {>=} 6 Pa with high transmittance values. We suggest that the observed changes in optical properties are due to an increasing number of oxygen vacancies as the growth argon pressure decreases.

  4. Chromium and Ruthenium-Doped Zinc Oxide Thin Films for Propane Sensing Applications

    Directory of Open Access Journals (Sweden)

    Maximino Avendaño-Alejo

    2013-03-01

    Full Text Available Chromium and ruthenium-doped zinc oxide (ZnO:Cr and (ZnO:Ru thin solid films were deposited on soda-lime glass substrates by the sol-gel dip-coating method. A 0.6 M solution of zinc acetate dihydrate dissolved in 2-methoxyethanol and monoethanolamine was used as basic solution. Chromium (III acetylacetonate and Ruthenium (III trichloride were used as doping sources. The Ru incorporation and its distribution profile into the films were proved by the SIMS technique. The morphology and structure of the films were studied by SEM microscopy and X-ray diffraction measurements, respectively. The SEM images show porous surfaces covered by small grains with different grain size, depending on the doping element, and the immersions number into the doping solutions. The sensing properties of ZnO:Cr and ZnO:Ru films in a propane (C3H8 atmosphere, as a function of the immersions number in the doping solution, have been studied in the present work. The highest sensitivity values were obtained for films doped from five immersions, 5.8 and 900, for ZnO:Cr and ZnO:Ru films, respectively. In order to evidence the catalytic effect of the chromium (Cr and ruthenium (Ru, the sensing characteristics of undoped ZnO films are reported as well.

  5. Nonlinear optical characterization of graphite oxide thin film by open aperture Z-scan technique

    Energy Technology Data Exchange (ETDEWEB)

    Sreeja, V. G.; Reshmi, R.; Devasia, Sebin; Anila, E. I., E-mail: anilaei@gmail.com [Optolectronic and Nanomaterials Research Laboratory, Department of Physics, Union Christian College, Aluva-683 102, Kerala (India); Cheruvalathu, Ajina [International School of Photonics, CUSAT, Cochin-22 (India)

    2016-05-23

    In this paper we explore the structural characterization of graphite oxide powder prepared from graphite powder by oxidation via modified Hummers method. The nonlinear optical properties of the spin coated graphite oxide thin film is also explored by open aperture Z-Scan technique. Structural and physiochemical properties of the samples were investigated with the help of Fourier Transform Infrared Spectroscopy (FTIR) and Raman Spectroscopy (Raman).The results of FT-IR and Raman spectroscopy showed that the graphite is oxidized by strong oxidants and the oxygen atoms are introduced into the graphite layers forming C=C, O-H and –C-H groups. The synthesized sample has good crystalline nature with lesser defects. The nonlinear optical property of GO thin film was studied by open aperture Z-Scan technique using Q-switched Nd-Yag Laser at 532 nm. The Z-scan plot showed that the investigated GO thin film has saturable absorption behavior. The nonlinear absorption coefficient and saturation intensity were also estimated to explore its applications in Q switched mode locking laser systems.

  6. Spectroscopic and luminescent properties of Co2+ doped tin oxide thin films by spray pyrolysis

    Directory of Open Access Journals (Sweden)

    K. Durga Venkata Prasad

    2016-07-01

    Full Text Available The wide variety of electronic and chemical properties of metal oxides makes them exciting materials for basic research and for technological applications alike. Oxides span a wide range of electrical properties from wide band-gap insulators to metallic and superconducting. Tin oxide belongs to a class of materials called Transparent Conducting Oxides (TCO which constitutes an important component for optoelectronic applications. Co2+ doped tin oxide thin films were prepared by chemical spray pyrolysis synthesis and characterized by powder X-ray diffraction, SEM, TEM, FT-IR, optical, EPR and PL techniques to collect the information about the crystal structure, coordination/local site symmetry of doped Co2+ ions in the host lattice and the luminescent properties of the prepared sample. Powder XRD data revealed that the crystal structure belongs to tetragonal rutile phase and its lattice cell parameters are evaluated. The average crystallite size was estimated to be 26 nm. The morphology of prepared sample was analyzed by using SEM and TEM studies. Functional groups of the prepared sample were observed in the FT-IR spectrum. Optical absorption and EPR studies have shown that on doping, Co2+ ions enter in the host lattice as octahedral site symmetry. PL studies of Co2+ doped SnO2 thin films exhibit blue and yellow emission bands. CIE chromaticity coordinates were also calculated from emission spectrum of Co2+ doped SnO2 thin films.

  7. Hydrothermal chemistry, structures, and luminescence studies of alkali hafnium fluorides.

    Science.gov (United States)

    Underwood, Christopher C; McMillen, Colin D; Chen, Hongyu; Anker, Jeffery N; Kolis, Joseph W

    2013-01-07

    This paper describes the hydrothermal chemistry of alkali hafnium fluorides, including the synthesis and structural characterization of five new alkali hafnium fluorides. Two ternary alkali hafnium fluorides are described: Li(2)HfF(6) in space group P31m with a = 4.9748(7) Å and c = 4.6449(9) Å and Na(5)Hf(2)F(13) in space group C2/m with a = 11.627(2) Å, b = 5.5159(11) Å, and c = 8.4317(17) Å. Three new alkali hafnium oxyfluorides are also described: two fluoroelpasolites, K(3)HfOF(5) and (NH(4))(3)HfOF(5), in space group Fm3m with a = 8.9766(10) and 9.4144(11) Å, respectively, and K(2)Hf(3)OF(12) in space group R3m with a = 7.6486(11) Å and c = 28.802(6) Å. Infrared (IR) spectra were obtained for the title solids to confirm the structure solutions. Comparison of these materials was made based on their structures and synthesis conditions. The formation of these species in hydrothermal fluids appears to be dependent upon both the concentration of the alkali fluoride mineralizer solution and the reaction temperature. Both X-ray and visible fluorescence studies were conducted on compounds synthesized in this study and showed that fluorescence was affected by a variety of factors, such as alkali metal size, the presence/absence of oxygen in the compound, and the coordination environment of Hf(4+).

  8. Pentamethylcyclopentadienyl Zirconium and Hafnium Polyhydride Complexes : Synthesis, Structure, and Reactivity

    NARCIS (Netherlands)

    Visser, Cindy; Hende, Johannes R. van den; Meetsma, Auke; Hessen, Bart; Teuben, Jan H.

    2001-01-01

    The half-sandwich zirconium and hafnium N,N-dimethylaminopropyl complexes Cp*M[(CH2)3NMe2]Cl2 (Cp* = η5-C5Me5, M = Zr, 1; Hf, 2) and Cp*M[(CH2)3NMe2]2Cl (M = Zr, 3; Hf, 4) were synthesized by mono- or dialkylation of Cp*MCl3 with the corresponding alkyllithium and Grignard reagents. Hydrogenolysis

  9. Reactions of zirconium and hafnium fluoride hydrates with hydrogen peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Gerasimova, S.O.; Polishchuk, S.A.; Avkhutskii, L.M.; Kalennik, V.M. (AN SSSR, Vladivostok. Inst. Khimii)

    1981-01-01

    Zirconium peroxofluoride of ZrO/sub 2/F/sub 2/x2H/sub 2/O composition is prepared by interaction of zirconium tetrafluoride trihydrate with hydrogen peroxide at pH 2-3. Hafnium peroxofluoride compound is not formed under similar conditions. It can be caused by their structural peculiarities for the compounds are not isostructural IR, PMR and NMR spectra for Zr peroxofluoride are presented.

  10. Lanthanum-oxide thin films deposited by plasma-enhanced atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eun-Joo; Ko, Myoung-Gyun; Kim, Beom-Yong; Park, Sang-Kyun; Kim, Heon-Do; Park, Jong-Wan [Hanyang University, Seoul (Korea, Republic of)

    2006-09-15

    Lanthanum oxide is suited as a gate oxide that can replace SiO{sub 2} due to its high dielectric constant with a band gap of 4.3 eV [1] and its thermal stability with silicon. In this work, La{sub 2}O{sub 3} thin films was performed on Si substrates by using plasma-enhanced atomic layer deposition with La(EtCp){sub 3} as the lanthanum precursor and O{sub 3} as the reactant gas. The fully saturated growth rate of lanthanum oxide films was 0.2 A/cycle at a plasma power of 500 W. Secondary ion mass spectrometry and Rutherford backscattering measurements detected no carbon impurity content.

  11. Metal Oxides Doped PPY-PVA Blend Thin Films Based Gas Sensor

    Directory of Open Access Journals (Sweden)

    D. B. DUPARE

    2009-02-01

    Full Text Available Synthesis of metal oxides doped polypyrrole–polyvinyl alcohol blend thin films by in situ chemical oxidative polymerization, using microwave oven on glass substrate for development of Ammonia and Trimethyl ammine hazardous gas sensor. The all experimental process carried out at room temperature(304 K. These polymer materials were characterized by Chemical analyses, spectral studies (UV-visible and IR and conductivity measurement by four –probe technique. The surface morphology as observed in the SEM image was observed to be uniformly covering the entire substrate surface. The sensor was used for different concentration (ppm of TMA and Ammonia gas investigation at room temperature (304 k. This study found to possess improved electrical, mechanical and environmental stability metal oxides doped PPY-PVA films.

  12. Activation of CO2 on transition metal surfaces and oxide supported metal thin films

    Science.gov (United States)

    Paul, Sujata; Buongiorno Nardelli, Marco

    2009-03-01

    Using first principles simulations based on Density Functional Theory, we have investigated the adsorption and activation properties of CO2 on a variety of transition metal surfaces and oxide supported metal thin films. We intend to focus on the chemical conversion of CO2 through heterogeneous catalysis using surfaces and interfaces where there is nanoscale control over charge density at the reactive sites. The activation of CO2 on clean metal surfaces is possible at very high temperatures and the situations changes drastically when reaction happens on oxide supported metal thin film. The chemical reactivity of the molecule on the surface depends on the charge rearrangement at the metal-alkaline earth oxide interface. We want to understand the possible catalytic systems and characterize the relevant geometrical and electronic parameters related to the reaction mechanisms, rates and yield.

  13. Comprehensive review on the development of high mobility in oxide thin film transistors

    Science.gov (United States)

    Choi, Jun Young; Lee, Sang Yeol

    2017-11-01

    Oxide materials are one of the most advanced key technology in the thin film transistors (TFTs) for the high-end of device applications. Amorphous oxide semiconductors (AOSs) have leading technique for flat panel display (FPD), active matrix organic light emitting display (AMOLED) and active matrix liquid crystal display (AMLCD) due to their excellent electrical characteristics, such as field effect mobility ( μ FE ), subthreshold swing (S.S) and threshold voltage ( V th ). Covalent semiconductor like amorphous silicon (a-Si) is attributed to the anti-bonding and bonding states of Si hybridized orbitals. However, AOSs have not grain boundary and excellent performances originated from the unique characteristics of AOS which is the direct orbital overlap between s orbitals of neighboring metal cations. High mobility oxide TFTs have gained attractive attention during the last few years and today in display industries. It is progressively developed to increase the mobility either by exploring various oxide semiconductors or by adopting new TFT structures. Mobility of oxide thin film transistor has been rapidly increased from single digit to higher than 100 cm2/V·s in a decade. In this review, we discuss on the comprehensive review on the mobility of oxide TFTs in a decade and propose bandgap engineering and novel structure to enhance the electrical characteristics of oxide TFTs.

  14. Influence of oblique-angle sputtered transparent conducting oxides on performance of Si-based thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Leem, Jung Woo; Yu, Jae Su [Department of Electronics and Radio Engineering, Kyung Hee University, 1 Seocheon-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of)

    2011-09-15

    The transparent conducting oxide (TCO) films with low-refractive-index (low-n) are fabricated by the oblique-angle sputtering method. By using the experimentally measured physical data of the fabricated low-n TCO films as the simulation parameters, the effect of low-n TCOs on the performance of a-Si:H/{mu}c-Si:H tandem thin film solar cells is investigated using Silvaco ATLAS. The Al-doped zinc oxide, indium tin oxide (ITO), and Sb-doped tin oxide films are deposited at the flux incidence angles of {theta}{sub i} = 0 (normal sputtering) and {theta}{sub i} = 80 from the sputtering target during the sputtering process. The oblique-angle sputtered films at {theta}{sub i} = 80 show the inclined columnar nanostructures compared to those at {theta}{sub i} = 0 , modifying the optical properties of the films. This is caused mainly by the increase of porosity within the film which leads to its low-n characteristics. The a-Si:H/{mu}c-Si:H tandem thin film solar cell incorporated with the low-n ITO film exhibits an improvement in the conversion efficiency of {proportional_to}1% under AM1.5g illumination because of its higher transmittance and lower absorption compared to that with the ITO film at {theta}{sub i} = 0 , indicating a conversion efficiency of 13.75%. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Interface engineered multifunctional oxide thin films with optimized properties

    Science.gov (United States)

    Collins, Gregory Roy

    2010-06-01

    In our world today, energy has become one of the most valuable resources, in particular, renewable and clean energy sources. The research presented here represents an investigation into three separate areas of this topic. In thin film applications, the ordered structures as well as the inherent thinness of the films precludes the normal physics found in bulk materials. Characterizations of films of this type can provide information on molecular level charge transfer processes of the film layer materials since diffusive properties are minimal. With the control given by pulsed laser deposition methods, film and interface structure can be altered allowing for an examination of these effects on the materials properties. For the electrolyte and cathode materials, this equates to finding thermal and PO2 dependencies for electronic and ionic transport. For barium titanate, aside from the effects of oxygen vacancies, the interface quality between the electrodes and the ferroelectric material determines the effectiveness of energy transfer between these boundaries. That is, poor bonding characteristics or the formation of intermediate layers will introduce inconsistencies and (possibly) unwanted piezoelectric response properties of the material which could introduce parasitic dampening (resistance) of the mechanical vibrations of a piezoelectric transducer, altering its resonant characteristics. The clean reaction products and potential for high power outputs provide a strong impetus into investigations of fuel cell structures to improve their functionality. With conventional applications being dominated by high temperature (>700 °C) cells utilizing YSZ as an electrolyte medium, much gain can be made in efficiency through the lowering of cell operation temperature. The first part of my research focuses on the growth and characterization of a novel multilayered electrolyte structure consisting of alternating layers of GCO and YSZ for use in a medium temperature (400--600

  16. Optoelectronics Devices Based on Zinc Oxide Thin Films and Nanostructures

    OpenAIRE

    Chu, Sheng

    2011-01-01

    Optoelectronics devices based on ZnO thin films and nanostructures are discussed in this dissertation. A ZnO homojunction LED was demonstrated. Sb-doped p-type ZnO and Ga-doped n-type ZnO on Si (100) substrate were used for the LED device. After achieving ohmic contacts on both types of ZnO, the device showed rectifying current-voltage (I-V) characteristics. Under forward bias, the device successfully showed ultraviolet emissions. The emission properties were analyzed and the emission was con...

  17. Oxide films at the nanoscale: new structures, new functions, and new materials.

    Science.gov (United States)

    Giordano, Livia; Pacchioni, Gianfranco

    2011-11-15

    We all make use of oxide ultrathin films, even if we are unaware of doing so. They are essential components of many common devices, such as mobile phones and laptops. The films in these ubiquitous electronics are composed of silicon dioxide, an unsurpassed material in the design of transistors. But oxide films at the nanoscale (typically just 10 nm or less in thickness) are integral to many other applications. In some cases, they form under normal reactive conditions and confer new properties to a material: one example is the corrosion protection of stainless steel, which is the result of a passive film. A new generation of devices for energy production and communications technology, such as ferroelectric ultrathin film capacitors, tunneling magnetoresistance sensors, solar energy materials, solid oxide fuel cells, and many others, are being specifically designed to exploit the unusual properties afforded by reduced oxide thickness. Oxide ultrathin films also have tremendous potential in chemistry, representing a rich new source of catalytic materials. About 20 years ago, researchers began to prepare model systems of truly heterogeneous catalysts based on thin oxide layers grown on single crystals of metal. Only recently, however, was it realized that these systems may behave quite differently from their corresponding bulk oxides. One of the phenomena uncovered is the occurrence of a spontaneous charge transfer from the metal support to an adsorbed species through the thin insulating layer (or vice versa). The importance of this property is clear: conceptually, the activation and bond breaking of adsorbed molecules begin with precisely the same process, electron transfer into an antibonding orbital. But electron transfer can also be harnessed to make a supported metal particle more chemically active, increase its adhesion energy, or change its shape. Most importantly, the basic principles underlying electron transfer and other phenomena (such as structural

  18. All-amorphous-oxide transparent, flexible thin-film transistors. Efficacy of bilayer gate dielectrics.

    Science.gov (United States)

    Liu, Jun; Buchholz, D Bruce; Hennek, Jonathan W; Chang, Robert P H; Facchetti, Antonio; Marks, Tobin J

    2010-09-01

    Optically transparent and mechanically flexible thin-film transistors (TF-TFTs) composed exclusively of amorphous metal oxide films are fabricated on plastic substrates by combining an amorphous Ta(2)O(5)/SiO(x) bilayer transparent oxide insulator (TOI) gate dielectric with an amorphous zinc-indium-tin oxide (a-ZITO) transparent oxide semiconductor (TOS) channel and a-ZITO transparent oxide conductor (TOC) electrodes. The bilayer gate dielectric is fabricated by the post-cross-linking of vapor-deposited hexachlorodisiloxane-derived films to form thin SiO(x) layers (v-SiO(x)) on amorphous Ta(2)O(5) (a-Ta(2)O(5)) films grown by ion-assisted deposition at room temperature. The a-Ta(2)O(5)/v-SiO(x) bilayer TOI dielectric integrates the large capacitance of the high dielectric constant a-Ta(2)O(5) layer with the excellent dielectric/semiconductor interfacial compatibility of the v-SiO(x) layer in a-ZITO TOS-based TF-TFTs. These all-amorphous-oxide TF-TFTs, having a channel length and width of 100 and 2000 microm, respectively, perform far better than a-Ta(2)O(5)-only devices and exhibit saturation-regime field-effect mobilities of approximately 20 cm(2)/V x s, on-currents >10(-4) A, and current on-off ratios >10(5). These TFTs operate at low voltages (approximately 4.0 V) and exhibit good visible-region optical transparency and excellent mechanical flexibility.

  19. Enhanced Reduction of Graphene Oxide on Recyclable Cu Foils to Fabricate Graphene Films with Superior Thermal Conductivity.

    Science.gov (United States)

    Huang, Sheng-Yun; Zhao, Bo; Zhang, Kai; Yuen, Matthew M F; Xu, Jian-Bin; Fu, Xian-Zhu; Sun, Rong; Wong, Ching-Ping

    2015-09-25

    Large-area freestanding graphene films are facilely fabricated by reducing graphene oxide films on recyclable Cu foils in H2-containing atmosphere at high temperature. Cu might act as efficient catalysts for considerably improved reduction of graphene oxide according to the SEM, EDS, XRD, XPS, Raman and TGA results. Comparing to the graphene films with ~30 μm thickness reduced without Cu substrate at 900 °C, the thermal conductivity and electrical conductivity of graphene films reduced on Cu foils are enhanced about 140% to 902 Wm(-1)K(-1) and 3.6 × 10(4) S/m, respectively. Moreover, the graphene films demonstrate superior thermal conductivity of ~1219 Wm(-1)K(-1) as decreasing the thickness of films to ~10 μm. The graphene films also exhibit excellent mechanical properties and flexibility.

  20. Composition of MBE-grown iron oxide films

    NARCIS (Netherlands)

    Voogt, F.C; Hibma, T; Smulders, P.J M; Niesen, L

    A wide range of iron oxides have been grown epitaxially on MgO(100) substrates using a dual beam technique in which the deposited iron is oxidised by a beam of NO2 particles. At high fluxes magnetite (Fe3-deltaO4) phases with compositions between near-stoichiometric magnetite (Fe3O4, delta = 0) and