WorldWideScience

Sample records for deposition cvd method

  1. Zirconium influence on microstructure of aluminide coatings deposited on nickel substrate by CVD method

    Indian Academy of Sciences (India)

    Jolanta Romanowska; Maryana Zagula-Yavorska; Jan Sieniawski

    2013-11-01

    Influence of Zr on the microstructure and phase characteristics of aluminide diffusion coatings deposited on the nickel substrate has been investigated in this study. The coatings with and without zirconium were deposited by CVD method. The cross-section chemical composition investigations revealed that during the coatings formation, there is an inward aluminum diffusion and outward nickel diffusion in both types of coatings (with and without zirconium), whereas zirconium is located far below the coating surface, at a depth of ∼17 m, between -NiAl phase and '-Ni3Al phase. XRD examinations showed that -NiAl, -NiAl and '-Ni3Al were the main components of the deposited coatings. -NiAl phase is on the surface of the coatings, whereas -NiAl and '-Ni3Al form deeper parts of the coatings. Zirconium is dissolved in NiAl on the border between -NiAl and '-Ni3Al.

  2. Purification of Single-walled Carbon Nanotubes Grown by a Chemical Vapour Deposition (CVD) Method

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A procedure for purification of single-walled carbon nanotubes(SWNTs) grown by the chemical vapour deposition (CVD) of carbon monooxide has been developed. Based on the result from TGA/DTA of as-prepared sample, the oxidation temperature was determined. The process included sonication, oxidation and acid washing steps. The purity and yield after purification were determined and estimated by TEM. Moreover, for the first time, a loop structure for CVD SWNTs has been observed.

  3. Deposition and Coating Properties on CVD Tungsten

    Institute of Scientific and Technical Information of China (English)

    DU Ji-hong; LI Zheng-xiang; LIU Gao-jian; ZHOU Hui-Huang; CHUN liang

    2004-01-01

    Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.

  4. Chemical vapor deposition (CVD) of uranium for alpha spectrometry; Deposicion quimica de vapor (CVD) de uranio para espectrometria alfa

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez V, M. L.; Rios M, C.; Ramirez O, J.; Davila R, J. I.; Mireles G, F., E-mail: luisalawliet@gmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)

    2015-09-15

    The uranium determination through radiometric techniques as alpha spectrometry requires for its proper analysis, preparation methods of the source to analyze and procedures for the deposit of this on a surface or substrate. Given the characteristics of alpha particles (small penetration distance and great loss of energy during their journey or its interaction with the matter), is important to ensure that the prepared sources are thin, to avoid problems of self-absorption. The routine methods used for this are the cathodic electro deposition and the direct evaporation, among others. In this paper the use of technique of chemical vapor deposition (CVD) for the preparation of uranium sources is investigated; because by this, is possible to obtain thin films (much thinner than those resulting from electro deposition or evaporation) on a substrate and comprises reacting a precursor with a gas, which in turn serves as a carrier of the reaction products to achieve deposition. Preliminary results of the chemical vapor deposition of uranium are presented, synthesizing and using as precursor molecule the uranyl acetylacetonate, using oxygen as carrier gas for the deposition reaction on a glass substrate. The uranium films obtained were found suitable for alpha spectrometry. The variables taken into account were the precursor sublimation temperatures and deposition temperature, the reaction time and the type and flow of carrier gas. Of the investigated conditions, two depositions with encouraging results that can serve as reference for further work to improve the technique presented here were selected. Alpha spectra obtained for these depositions and the characterization of the representative samples by scanning electron microscopy and X-ray diffraction are also presented. (Author)

  5. High-rate diamond deposition by microwave plasma CVD

    Science.gov (United States)

    Li, Xianglin

    In this dissertation, the growth of CVD (Chemical Vapor Deposition) diamond thin films is studied both theoretically and experimentally. The goal of this research is to deposit high quality HOD (Highly Oriented Diamond) films with a growth rate greater than 1 mum/hr. For the (100)-oriented HOD films, the growth rate achieved by the traditional process is only 0.3 mum/hr while the theoretical limit is ˜0.45 mum/hr. This research increases the growth rate up to 5.3 mum/hr (with a theoretical limit of ˜7 mum/hr) while preserving the crystal quality. This work builds a connection between the theoretical study of the CVD process and the experimental research. The study is extended from the growth of regular polycrystalline diamond to highly oriented diamond (HOD) films. For the increase of the growth rate of regular polycrystalline diamond thin films, a scaling growth model developed by Goodwin is introduced in details to assist in the understanding of the MPCVD (Microwave Plasma CVD) process. Within the Goodwin's scaling model, there are only four important sub-processes for the growth of diamond: surface modification, adsorption, desorption, and incorporation. The factors determining the diamond growth rate and film quality are discussed following the description of the experimental setup and process parameters. Growth rate and crystal quality models are reviewed to predict and understand the experimental results. It is shown that the growth rate of diamond can be increased with methane input concentration and the amount of atomic hydrogen (by changing the total pressure). It is crucial to provide enough atomic hydrogen to conserve crystal quality of the deposited diamond film. The experimental results demonstrate that for a fixed methane concentration, there is a minimum pressure for growth of good diamond. Similarly, for a fixed total pressure, there is a maximum methane concentration for growth of good diamond, and this maximum methane concentration increases

  6. EFFECTS OF OPERATING CONDITIONS ON THE DEPOSITION OF GaAs IN A VERTICAL CVD REACTOR

    OpenAIRE

    JAE-SANG BAEK; JIN-HYO BOO; YOUN-JEA KIM

    2008-01-01

    A numerical study is needed to gain insight into the growth mechanism and improve the reactor design or optimize the deposition condition in chemical vapor deposition (CVD). In this study, we have performed a numerical analysis of the deposition of gallium arsenide (GaAs) from trimethyl gallium (TMG) and arsine in a vertical CVD reactor. The effects of operating parameters, such as the rotation velocity of susceptor, inlet velocity, and inlet TMG fraction, are investigated and presented. The ...

  7. Rare earth-doped alumina thin films deposited by liquid source CVD processes

    Energy Technology Data Exchange (ETDEWEB)

    Deschanvres, J.L.; Meffre, W.; Joubert, J.C.; Senateur, J.P. [Ecole Nat. Superieure de Phys. de Grenoble, St. Martin d`Heres (France). Lab. des Materiaux et du Genie Phys.; Robaut, F. [Consortium des Moyens Technologiques Communs, Institut National Polytechnique de Grenoble, BP 75, 38402 St Martin d`Heres (France); Broquin, J.E.; Rimet, R. [Laboratoire d`Electromagnetisme, Microondes et Optoelectronique, CNRS-Ecole Nationale Superieure d`Electronique et Radioelectricite de Grenoble, BP 257, 38016 Grenoble, Cedex (France)

    1998-07-24

    Two types of liquid-source CVD processes are proposed for the growth of rare earth-doped alumina thin films suitable as amplifying media for integrated optic applications. Amorphous, transparent, pure and erbium- or neodymium-doped alumina films were deposited between 573 and 833 K by atmospheric pressure aerosol CVD. The rare earth doping concentration increases by decreasing the deposition temperature. The refractive index of the alumina films increases as a function of the deposition temperature from 1.53 at 573 K to 1.61 at 813 K. Neodymium-doped films were also obtained at low pressure by liquid source injection CVD. (orig.) 7 refs.

  8. Simultaneous synthesis of nanodiamonds and graphene via plasma enhanced chemical vapor deposition (MW PE-CVD) on copper.

    Science.gov (United States)

    Gottlieb, Steven; Wöhrl, Nicolas; Schulz, Stephan; Buck, Volker

    2016-01-01

    The simultaneous growth of both nanodiamonds and graphene on copper samples is described for the first time. A PE-CVD process is used to synthesize graphene layers and nanodiamond clusters from a hydrogen/methane gas mixture as it is typically done successfully in thermal CVD processes for graphene synthesis. However, the standard thermal CVD process is not without problems since the deposition of graphene is affected by the evaporation of a notable amount of copper caused by the slow temperature increase typical for thermal CVD resulting in a long process time. In sharp contrast, the synthesis of graphene by PE-CVD can circumvent this problem by substantially shortening the process time at holding out the prospect of a lower substrate temperature. The reduced thermal load and the possibility to industrially scale-up the PE-CVD process makes it a very attractive alternative to the thermal CVD process with respect to the graphene production in the future. Nanodiamonds are synthesized in PE-CVD reactors for a long time because these processes offer a high degree of control over the film's nanostructure and simultaneously providing a significant high deposition rate. To model the co-deposition process, the three relevant macroscopic parameters (pressure, gas mixture and microwave power) are correlated with three relevant process properties (plasma ball size, substrate temperature and C2/Hα-ratio) and the influence on the quality of the deposited carbon allotropes is investigated. For the evaluation of the graphene as well as the nanodiamond quality, Raman spectroscopy used whereas the plasma properties are measured by optical methods. It is found that the diamond nucleation can be influenced by the C2/Hα-ratio in the plasma, while the graphene quality remains mostly unchanged by this parameter. Moreover it is derived from the experimental data that the direct plasma contact with the copper surface is beneficial for the nucleation of the diamond while the growth and

  9. Tantalum Coating of Steel, Copper, Aluminum, and Titanium by Thermal Chemical Vapor Deposition (CVD)

    DEFF Research Database (Denmark)

    Christensen, Erik; Bjerrum, Niels

    1998-01-01

    Tantalum coatings ranging from 0.5 to 120 mm has been deposited by CVD at 625-1000 C using tantalum pentachloride as precursor. Deposition rates range from 1 to 80mm/h and an activation energy of 103 kJ/mole is calculated. Well adhering deposits has been obtained on stainless steel, carbon steels...

  10. An economic CVD technique for pure SnO2 thin films deposition: Temperature effects

    Indian Academy of Sciences (India)

    M Maleki; S M Rozati

    2013-04-01

    A modified new method of CVD for formation of pure layers of tin oxide films was developed. This method is very simple and inexpensive and produces films with good electrical properties. The effect of substrate temperature on the sheet resistance, resistivity, mobility, carrier concentration and transparency of the films has been studied. The best sheet resistance obtained at substrate temperature of 500 ◦C was about 27 /cm2. X-ray diffraction showed that the structure of deposited films was polycrystalline with a grain size between 150–300 Å. The preferred orientation was (211) for films deposited at substrate temperature of about 500 °C. FESEM micrographs revealed that substrate temperature is an important factor for increasing grain size and modifies electrical parameters. UV-visible measurement showed reduction of transparency and bandgap of the layers with increasing substrate temperature.

  11. Improved CVD Techniques for Depositing Passivation Layers of ICs

    Science.gov (United States)

    1975-10-01

    went into compressive stress of 1.3 x 10 dynes/cm2. Results NX • thus show that room-temperature stress in CVD films can be reduced to nearly 35 -4 0...fluorescence working curves. X-ray fluorescence radiation measurements were carried out using a Siemens Crystalloflex 4 x-ray generator with a chromium target x...ray tube (2000 W) and a Siemens Vacuum X-Ray Spectrometer Model VRS. Sample area of measurement was usually 0.50 cm2 . 2= Experimental results will be

  12. Thin alumina and silica films by chemical vapor deposition (CVD)

    OpenAIRE

    Hofman, R.; Morssinkhof, R.W.J.; Fransen, T.; Westheim, J.G.F.; Gellings, P.J.

    1993-01-01

    Alumina and silica coatings have been deposited by MOCVD (Metal Organic Chemical Vapor Deposition) on alloys to protect them against high temperature corrosion. Aluminium Tri-lsopropoxide (ATI) and DiAcetoxyDitertiaryButoxySilane (DAOBS) have been used as metal organic precursors to prepare these ceramic coatings. The influence of several process steps on the deposition rate and surface morphology is discussed. The deposition of SiO2 at atmospheric pressure is kinetically limited below 833 K ...

  13. A Study on Medium Temperature Chemical Vapor Deposition (MT-CVD) Technology and Super Coating Materials

    Institute of Scientific and Technical Information of China (English)

    GAO Jian; LI Jian-ping; ZENG Xiang-cai; MA Wen-cun

    2004-01-01

    In this paper, the dense and columnar crystalline TiCN coating layers with very good bonding strength between a layer and another layer was deposited using Medium Temperature Chemical Vapor Deposition (MT-CVD) where CH3CN organic composite with C/N atomic clusters etc. was utilized at 700 ~ 900 ℃. Effect of coating processing parameters, such as coating temperature, pressure and different gas flow quantity on structures and properties of TiCN coating layers were investigated. The super coating mechanis mand structures were analyzed. The new coating processing parameters and properties of carbide inserts with super coating layers were gained by using the improved high temperature chemical vapor deposition (HTCVD) equipment and HT-CVD, in combination with MT-CVD technology.

  14. Thin alumina and silica films by chemical vapor deposition (CVD)

    NARCIS (Netherlands)

    Hofman, R.; Morssinkhof, R.W.J.; Fransen, T.; Westheim, J.G.F.; Gellings, P.J.

    1993-01-01

    Alumina and silica coatings have been deposited by MOCVD (Metal Organic Chemical Vapor Deposition) on alloys to protect them against high temperature corrosion. Aluminium Tri-lsopropoxide (ATI) and DiAcetoxyDitertiaryButoxySilane (DAOBS) have been used as metal organic precursors to prepare these ce

  15. Oxidation Resistance of CVD (Chemical Vapor Deposition) Coatings

    Science.gov (United States)

    1987-02-01

    carbonaceous residuoe were overcome, and dense, iadherent, coat-ings which :ýtop oxidat-ion Of the substrate art! reliably produced. The iridium deposition...flow, pressure and geometry within the reaction chamber, and substrate material. For the coating to have high integrity and adhesion to the substrate...entirely produced by Ultramet using chemical vapor deposition and a novel integrated fabrication technique. Coating the inside of a long chamber presents

  16. 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.

  17. Synthesis of crystalline Ge nanoclusters in PE-CVD-deposited SiO2 films

    DEFF Research Database (Denmark)

    Leervad Pedersen, T.P.; Skov Jensen, J.; Chevallier, J.

    2005-01-01

    The synthesis of evenly distributed Ge nanoclusters in plasma-enhanced chemical-vapour-deposited (PE-CVD) SiO2 thin films containing 8 at. % Ge is reported. This is of importance for the application of nanoclusters in semiconductor technology. The average diameter of the Ge nanoclusters can...

  18. Advances in the chemical vapor deposition (CVD) of Tantalum

    DEFF Research Database (Denmark)

    Mugabi, James Atwoki; Eriksen, Søren; Christensen, Erik

    2014-01-01

    The chemical stability of tantalum in hot acidic media has made it a key material in the protection of industrial equipment from corrosion under such conditions. The Chemical Vapor Deposition of tantalum to achieve such thin corrosion resistant coatings is one of the most widely mentioned examples...

  19. Deposition of TiC film on titanium for abrasion resistant implant material by ion-enhanced triode plasma CVD

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Yuhe, E-mail: zyh1120@hotmail.co.jp [School of Stomatology, China Medical University, Shen Yang (China); Wang Wei; Jia Xingya [School of Stomatology, China Medical University, Shen Yang (China); Akasaka, Tsukasa [Department of Health Science, School of Dental Medicine Hokkaido University, Sapporo (Japan); Liao, Susan [School of Materials Science and Engineering, Nanyang Technological University (Singapore); Watari, Fumio [Department of Health Science, School of Dental Medicine Hokkaido University, Sapporo (Japan)

    2012-12-01

    Highlights: Black-Right-Pointing-Pointer Deposition of Titanium Carbide (TiC) layer on titanium (Ti) surface has been demonstrated by an ion-enhanced triode plasma chemical vapor deposition (CVD) method. Black-Right-Pointing-Pointer The Vickers hardness of surface carbide was more than 2000, which confirmed its high abrasion resistance. Black-Right-Pointing-Pointer Physical and mechanical properties of the deposited TiC film on Ti were investigated to examine its potential application as an abrasion resistant implant material. - Abstract: Deposition of titanium carbide (TiC) layer on titanium (Ti) surface has been demonstrated by an ion-enhanced triode plasma chemical vapor deposition (CVD) method using a TiCl{sub 4} + CH{sub 4} + H{sub 2} gas mixture. Physical and mechanical properties of the deposited TiC film on Ti were investigated to examine its potential application as an abrasion resistant implant material. X-ray diffraction (XRD) showed that the specimen was consisted of TiC and Ti. Carbide layer of about 6 {mu}m thickness was observed on the cross section of the specimen by scanning electron microscopy (SEM). The Vickers hardness of surface carbide was more than 2000, which confirmed its high abrasion resistance.

  20. Numerical modeling of chemical vapor deposition (CVD) in a horizontal reactor

    Science.gov (United States)

    Sheikholeslami, M. Z.; Jasinski, T.; Fretz, K. W.

    1988-01-01

    In the present numerical prediction of the deposition rate of silicon from silane in a CVD process, the conservation equations for mass, momentum, energy, and chemical species are solved on a staggered grid using the SIMPLE algorithm, while the rate of chemical reactions in the gas phase and on the susceptor surface is obtained from an Arrhenius rate equation. Predicted deposition rates as a function of position along the susceptor with and without the gas phase chemical reaction are compared with the available experimental and numerical data; agreement is excellent except at the leading edge of the susceptor, where the deposition rate is overpredicted.

  1. Superhydrophobic Copper Surfaces with Anticorrosion Properties Fabricated by Solventless CVD Methods.

    Science.gov (United States)

    Vilaró, Ignasi; Yagüe, Jose L; Borrós, Salvador

    2017-01-11

    Due to continuous miniaturization and increasing number of electrical components in electronics, copper interconnections have become critical for the design of 3D integrated circuits. However, corrosion attack on the copper metal can affect the electronic performance of the material. Superhydrophobic coatings are a commonly used strategy to prevent this undesired effect. In this work, a solventless two-steps process was developed to fabricate superhydrophobic copper surfaces using chemical vapor deposition (CVD) methods. The superhydrophobic state was achieved through the design of a hierarchical structure, combining micro-/nanoscale domains. In the first step, O2- and Ar-plasma etchings were performed on the copper substrate to generate microroughness. Afterward, a conformal copolymer, 1H,1H,2H,2H-perfluorodecyl acrylate-ethylene glycol diacrylate [p(PFDA-co-EGDA)], was deposited on top of the metal via initiated CVD (iCVD) to lower the surface energy of the surface. The copolymer topography exhibited a very characteristic and unique nanoworm-like structure. The combination of the nanofeatures of the polymer with the microroughness of the copper led to achievement of the superhydrophobic state. AFM, SEM, and XPS were used to characterize the evolution in topography and chemical composition during the CVD processes. The modified copper showed water contact angles as high as 163° and hysteresis as low as 1°. The coating withstood exposure to aggressive media for extended periods of time. Tafel analysis was used to compare the corrosion rates between bare and modified copper. Results indicated that iCVD-coated copper corrodes 3 orders of magnitude slower than untreated copper. The surface modification process yielded repeatable and robust superhydrophobic coatings with remarkable anticorrosion properties.

  2. Abnormal Crystallization of Silicon Thin Films Deposited by ICP-CVD

    Institute of Scientific and Technical Information of China (English)

    LI Jun-Shuai; YIN Min; WANG Jin-Xiao; HE De-Yan

    2005-01-01

    @@ Silicon thin films are deposited by inductively coupled plasma chemical vapour deposition (ICP-CVD) at a low temperature of 350℃ using a mixture of SiH4 and H2. The structures of the films are characterized by x-ray diffraction and Raman spectra. Under the optimum experimental conditions, we observe that the crystallinity of Si films becomes more excellent and the preferred orientation changes from (111) to (220) with the decreasing dilution of SiH4 in H2. Such an abnormal crystallization is tentatively interpreted in term of the high density,low electron temperature and spatial confinement of the plasma in the process of ICP-CVD.

  3. Deposition of device quality silicon nitride with ultra high deposition rate (> 7 nm/s) using hot-wire CVD

    NARCIS (Netherlands)

    Verlaan, V.; Houweling, Z.S.; van der Werf, C.H.M.; Romijn, I.G.; Schropp, R.E.I.; Goldbach, H.D.

    2008-01-01

    The application of hot-wire (HW) CVD deposited silicon nitride (SiNx) as passivating anti-reflection coating on multicrystalline silicon (mc-Si) solar cells is investigated. The highest efficiency reached is 15.7% for SiNx layers with an N/Si ratio of 1.20 and a high mass density of 2.9 g/cm3. These

  4. A novel Mo-W interlayer approach for CVD diamond deposition on steel

    Directory of Open Access Journals (Sweden)

    Vojtěch Kundrát

    2015-04-01

    Full Text Available Steel is the most widely used material in engineering for its cost/performance ratio and coatings are routinely applied on its surface to further improve its properties. Diamond coated steel parts are an option for many demanding industrial applications through prolonging the lifetime of steel parts, enhancement of tool performance as well as the reduction of wear rates. Direct deposition of diamond on steel using conventional chemical vapour deposition (CVD processes is known to give poor results due to the preferential formation of amorphous carbon on iron, nickel and other elements as well as stresses induced from the significant difference in the thermal expansion coefficients of those materials. This article reports a novel approach of deposition of nanocrystalline diamond coatings on high-speed steel (M42 substrates using a multi-structured molybdenum (Mo – tungsten (W interlayer to form steel/Mo/Mo-W/W/diamond sandwich structures which overcome the adhesion problem related to direct magnetron sputtering deposition of pure tungsten. Surface, interface and tribology properties were evaluated to understand the role of such an interlayer structure. The multi-structured Mo-W interlayer has been proven to improve the adhesion between diamond films and steel substrates by acting as an effective diffusion barrier during the CVD diamond deposition.

  5. A novel Mo-W interlayer approach for CVD diamond deposition on steel

    Energy Technology Data Exchange (ETDEWEB)

    Kundrát, Vojtěch; Sullivan, John; Ye, Haitao, E-mail: h.ye@aston.ac.uk [School of Engineering and Applied Science, Aston University, Birmingham, B4 7ET (United Kingdom); Zhang, Xiaoling; Cooke, Kevin; Sun, Hailin [Miba Coating Group: Teer Coatings Ltd, West-Stone-House, West-Stone, Berry-Hill-Industrial-Estate, WR9 9AS, Droitwich (United Kingdom)

    2015-04-15

    Steel is the most widely used material in engineering for its cost/performance ratio and coatings are routinely applied on its surface to further improve its properties. Diamond coated steel parts are an option for many demanding industrial applications through prolonging the lifetime of steel parts, enhancement of tool performance as well as the reduction of wear rates. Direct deposition of diamond on steel using conventional chemical vapour deposition (CVD) processes is known to give poor results due to the preferential formation of amorphous carbon on iron, nickel and other elements as well as stresses induced from the significant difference in the thermal expansion coefficients of those materials. This article reports a novel approach of deposition of nanocrystalline diamond coatings on high-speed steel (M42) substrates using a multi-structured molybdenum (Mo) – tungsten (W) interlayer to form steel/Mo/Mo-W/W/diamond sandwich structures which overcome the adhesion problem related to direct magnetron sputtering deposition of pure tungsten. Surface, interface and tribology properties were evaluated to understand the role of such an interlayer structure. The multi-structured Mo-W interlayer has been proven to improve the adhesion between diamond films and steel substrates by acting as an effective diffusion barrier during the CVD diamond deposition.

  6. Properties of Boron-dopedμc-Ge:H Films Deposited by Hot-wire CVD

    Institute of Scientific and Technical Information of China (English)

    HUANG Haibin; SHEN Honglie; WU Tianru; LU Linfeng; TANG Zhengxia; SHEN Jiancang

    2015-01-01

    Boron-doped hydrogenated microcrystalline Germanium (μc-Ge:H)fi lms were deposited by hot-wire CVD. H2 diluted GeH4 and B2H6 were used as precursors and the substrate temperature was kept at 300ć. The properties of the samples were analyzed by XRD, Raman spectroscopy, Fourier transform infrared spectrometer and Hall Effect measurement with Van der Pauw method. It is found that thefi lms are partially crystallized, with crystalline fractions larger than 45% and grain sizes smaller than 50 nm. The B-doping can enhance the crystallization but reduce the grain sizes, and also enhance the preferential growth of Ge (220). The conductivity of thefi lms increases and tends to be saturated with increasingdiborane-to-germane ratio . All the Hall mobilities of the samples are larger than 3.8 cm2·V-1·s-1. A high conductivity of 41.3Ω-1ίcm-1 is gained at=6.7%.

  7. Oxidation Resistance of Turbine Blades Made of ŻS6K Superalloy after Aluminizing by Low-Activity CVD and VPA Methods

    Science.gov (United States)

    Zagula-Yavorska, M.; Kocurek, P.; Pytel, M.; Sieniawski, J.

    2016-05-01

    Two aluminide layers (additive and interdiffusion) were deposited on a turbine blade made of ŻS6K superalloy by means of VPA and CVD methods. The additive and interdiffusion layers obtained by the VPA method consist of the NiAl phase and some carbides, while the additive layer deposited by the CVD method consists of the NiAl phase only. The residual stresses in the aluminide coating at the lock, suction side, and pressure side of the blade were tensile. The aluminide coating deposited by the CVD method has an oxidation resistance about 7 times better than that deposited by the VPA method. Al2O3 + HfO2 + NiAl2O4 phases were revealed on the surface of the aluminide coating deposited by the VPA method after 240 h oxidation. Al2O3 + TiO2 oxides were found on the surface of the aluminide coating deposited by the CVD method after 240 h oxidation. Increasing the time of oxidation from 240 to 720 h led to the formation of the NiO oxide on the surface of the coating deposited by the VPA method. Al2O3 oxide is still visible on the surface of the coating deposited by the CVD method. The residual stresses in the aluminide coating after 30 cycles of oxidation at the lock, suction side and pressure side of the turbine blade are compressive.

  8. Stable dropwise condensation for enhancing heat transfer via the initiated chemical vapor deposition (iCVD) of grafted polymer films.

    Science.gov (United States)

    Paxson, Adam T; Yagüe, Jose L; Gleason, Karen K; Varanasi, Kripa K

    2014-01-22

    Ultra-thin copolymer films are deposited by initiated chemical deposition (iCVD) to investigate their performance under the condensation of water vapor. By forming a grafted interface between the coating and the substrate, the films exhibit stable dropwise condensation even when subjected to 100 °C steam. The applicability of the iCVD to complex substrate geometries is demonstrated on a copper condenser coil.

  9. Fast method for reactor and feature scale coupling in ALD and CVD

    Energy Technology Data Exchange (ETDEWEB)

    Yanguas-Gil, Angel; Elam, Jeffrey W.

    2017-08-08

    Transport and surface chemistry of certain deposition techniques is modeled. Methods provide a model of the transport inside nanostructures as a single-particle discrete Markov chain process. This approach decouples the complexity of the surface chemistry from the transport model, thus allowing its application under general surface chemistry conditions, including atomic layer deposition (ALD) and chemical vapor deposition (CVD). Methods provide for determination of determine statistical information of the trajectory of individual molecules, such as the average interaction time or the number of wall collisions for molecules entering the nanostructures as well as to track the relative contributions to thin-film growth of different independent reaction pathways at each point of the feature.

  10. Effect of substrate bias on deposition behaviour of charged silicon nanoparticles in ICP-CVD process

    Science.gov (United States)

    Yoo, Seung-Wan; You, Shin-Jae; Kim, Jung-Hyung; Seong, Dae-Jin; Seo, Byong-Hoon; Hwang, Nong-Moon

    2017-01-01

    The effect of a substrate bias on the deposition behaviour of crystalline silicon films during inductively coupled plasma chemical vapour deposition (ICP-CVD) was analysed by consideration of non-classical crystallization, in which the building block is a nanoparticle rather than an individual atom or molecule. The coexistence of positively and negatively charged nanoparticles in the plasma and their role in Si film deposition are confirmed by applying bias voltages to the substrate, which is sufficiently small as not to affect the plasma potential. The sizes of positively and negatively charged nanoparticles captured on a carbon membrane and imaged using TEM are, respectively, 2.7-5.5 nm and 6-13 nm. The film deposited by positively charged nanoparticles has a typical columnar structure. In contrast, the film deposited by negatively charged nanoparticles has a structure like a powdery compact with the deposition rate about three times higher than that for positively charged nanoparticles. All the films exhibit crystallinity even though the substrate is at room temperature, which is attributed to the deposition of crystalline nanoparticles formed in the plasma. The film deposited by negatively charged nanoparticles has the highest crystalline fraction of 0.84.

  11. Synthesis of Different Layers of Graphene on Stainless Steel Using the CVD Method.

    Science.gov (United States)

    Ghaemi, Ferial; Abdullah, Luqman Chuah; Tahir, Paridah Md; Yunus, Robiah

    2016-12-01

    In this study, different types of graphene, including single-, few-, and multi-layer graphene, were grown on a stainless steel (SS) mesh coated with Cu catalyst by using the chemical vapor deposition (CVD) method. Even though the SS mesh consisted of different types of metals, such as Fe, Ni, and Cr, which can also be used as catalysts, the reason for coating Cu catalyst on the SS surface had been related to the nature of the Cu, which promotes the growth of graphene with high quality and quantity at low temperature and time. The reaction temperature and run time, as the most important parameters of the CVD method, were varied, and thus led to the synthesis of different layers of graphene. Moreover, the presence of single-, few-, and multi-layer graphene was confirmed by employing two techniques, namely transmission electron microscopy (TEM) and Raman spectroscopy. On top of that, electron dispersive X-ray (EDX) was further applied to establish the influence of the CVD parameters on the growth of graphene.

  12. Synthesis of Different Layers of Graphene on Stainless Steel Using the CVD Method

    Science.gov (United States)

    Ghaemi, Ferial; Abdullah, Luqman Chuah; Tahir, Paridah Md; Yunus, Robiah

    2016-11-01

    In this study, different types of graphene, including single-, few-, and multi-layer graphene, were grown on a stainless steel (SS) mesh coated with Cu catalyst by using the chemical vapor deposition (CVD) method. Even though the SS mesh consisted of different types of metals, such as Fe, Ni, and Cr, which can also be used as catalysts, the reason for coating Cu catalyst on the SS surface had been related to the nature of the Cu, which promotes the growth of graphene with high quality and quantity at low temperature and time. The reaction temperature and run time, as the most important parameters of the CVD method, were varied, and thus led to the synthesis of different layers of graphene. Moreover, the presence of single-, few-, and multi-layer graphene was confirmed by employing two techniques, namely transmission electron microscopy (TEM) and Raman spectroscopy. On top of that, electron dispersive X-ray (EDX) was further applied to establish the influence of the CVD parameters on the growth of graphene.

  13. Optical and mechanical properties of diamond like carbon films deposited by microwave ECR plasma CVD

    Indian Academy of Sciences (India)

    S B Singh; M Pandey; N Chand; A Biswas; D Bhattacharya; S Dash; A K Tyagi; R M Dey; S K Kulkarni; D S Patil

    2008-10-01

    Diamond like carbon (DLC) films were deposited on Si (111) substrates by microwave electron cyclotron resonance (ECR) plasma chemical vapour deposition (CVD) process using plasma of argon and methane gases. During deposition, a d.c. self-bias was applied to the substrates by application of 13.56 MHz rf power. DLC films deposited at three different bias voltages (–60 V, –100 V and –150 V) were characterized by FTIR, Raman spectroscopy and spectroscopic ellipsometry to study the variation in the bonding and optical properties of the deposited coatings with process parameters. The mechanical properties such as hardness and elastic modulus were measured by load depth sensing indentation technique. The DLC film deposited at –100 V bias exhibit high hardness (∼ 19 GPa), high elastic modulus (∼ 160 GPa) and high refractive index (∼ 2.16–2.26) as compared to films deposited at –60 V and –150 V substrate bias. This study clearly shows the significance of substrate bias in controlling the optical and mechanical properties of DLC films.

  14. Faraday effect of bismuth iron garnet thin film prepared by mist CVD method

    Science.gov (United States)

    Yao, Situ; Sato, Takafumi; Kaneko, Kentaro; Murai, Shunsuke; Fujita, Koji; Tanaka, Katsuhisa

    2015-06-01

    Metastable bismuth iron garnet (BIG, an abbreviation of Bi3Fe5O12), one kind of garnet-type ferrites, is known to manifest very large Faraday rotation as well as low optical absorption in the visible to infrared region. We report on successful synthesis of thin film composed of single-phase BIG epitaxially grown on single-crystalline gadolinium gallium garnet (Gd3Ga5O12, GGG) substrate by using mist chemical vapor deposition (CVD) method, which is an emerging technique for preparation of thin films. The crystal structure, surface morphology, and magnetic, optical and magneto-optical properties of the resultant thin films have been explored. The BIG thin film has a relatively flat surface free from roughness compared to those prepared by other vapor deposition methods. Saturation magnetization is about 1620 G at room temperature, which is close to that expected from the ideal magnetic structure of BIG. The maximum value of Faraday rotation angle reaches 54.3 deg/µm at a wavelength of 424 nm. This value is rather large when compared with those reported for BIG thin films prepared by other techniques. The wavelength dependence of Faraday rotation angle is analyzed well in terms of the crystal electric field (CEF) level schema. Our result suggests that the mist CVD method is a simple and effective technique to synthesize BIG thin film with excellent magneto-optical properties.

  15. Deposition of ZnO Films on Freestanding CVD Thick Diamond Films

    Institute of Scientific and Technical Information of China (English)

    SUN Jian; BAI Yi-Zhen; YANG Tian-Peng; XU Yi-Bin; WANG Xin-Sheng; DU Guo-Tong; WU Han-Hua

    2006-01-01

    @@ For ZnO/diamond structured surface acoustic wave (SAW) filters, performance is sensitively dependent on the quality of the ZnO films. In this paper, we prepare highly-oriented and fine grained polycrystalline ZnO thin films with excellent surface smoothness on the smooth nucleation surfaces of freestanding CVD diamond films by metal organic chemical vapour deposition (MOCVD). The properties of the ZnO films are characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL) spectrum. The influences of the deposition conditions on the quality of ZnO films are discussed briefly. ZnO/freestanding thick-diamond-film layered SAW devices with high response frequencies are expected to be developed.

  16. Field emission from carbon films deposited by VHF CVD on difference substrates

    Energy Technology Data Exchange (ETDEWEB)

    Abramov, A A; Andronov, A N; Felter, T E; Ioffe, A F; Kosarev, A I; Shotov, M V; Vinogradov, A J

    1999-04-01

    As previously demonstrated, non-diamond carbon (NDC) films deposited at low temperatures 200-300 C on silicon tips reduced the threshold of field emission. In this paper we will present the results of the study of field emission from flat NDC films prepared by VHF CVD. Emission measurements were performed in a diode configuration at approximately 10{sup {minus}10} Torr. NDC films were deposited on ceramic and on c-Si substrates sputter coated with layers of Ti, Cu, Ni and Pt. The back contact material influences the emission characteristics but not as a direct correlation to work function. A model of field emission from metal-NDC film structures will be discussed.

  17. A Bayesian method to estimate the neutron response matrix of a single crystal CVD diamond detector

    Energy Technology Data Exchange (ETDEWEB)

    Reginatto, Marcel; Araque, Jorge Guerrero; Nolte, Ralf; Zbořil, Miroslav; Zimbal, Andreas [Physikalisch-Technische Bundesanstalt, D-38116 Braunschweig (Germany); Gagnon-Moisan, Francis [Paul Scherrer Institut, CH-5232 Villigen (Switzerland)

    2015-01-13

    Detectors made from artificial chemical vapor deposition (CVD) single crystal diamond are very promising candidates for applications where high resolution neutron spectrometry in very high neutron fluxes is required, for example in fusion research. We propose a Bayesian method to estimate the neutron response function of the detector for a continuous range of neutron energies (in our case, 10 MeV ≤ E{sub n} ≤ 16 MeV) based on a few measurements with quasi-monoenergetic neutrons. This method is needed because a complete set of measurements is not available and the alternative approach of using responses based on Monte Carlo calculations is not feasible. Our approach uses Bayesian signal-background separation techniques and radial basis function interpolation methods. We present the analysis of data measured at the PTB accelerator facility PIAF. The method is quite general and it can be applied to other particle detectors with similar characteristics.

  18. Initiated Chemical Vapor Deposition (iCVD) Polymer Thin Films: Structure-Property Effects on Thermal Degradation and Adhesion

    Science.gov (United States)

    Bharamaiah Jeevendrakumar, Vijay Jain

    Opportunities and challenges for chemical vapor deposition (CVD) of polymer thin films stems from their applications in electronics, sensors, and adhesives with demands for control over film composition, conformity and stability. Initiated chemical vapor deposition (iCVD) is a subset of the CVD technique that conjoins bulk free-radical polymerization chemistry with gas-phase processing. The novelty of iCVD technique stems from the use of an initiator that can be activated at low energies (150 -- 300 °C) to react with surface adsorbed monomer to form a polymer film. This reduces risk for potential unwarranted side-reactions. Until recently, majority of iCVD research was limited to understanding the deposition kinetics with monomer properties being the principal parameters. However, there is a lack of study on the properties of deposited films which is critical for utilizing the technique in any real-world applications. The work presented here aims to advance investigation in this direction by characterizing the thermal properties of iCVD polymer films with primary focus on the initiators. A detailed characterization of custom-built iCVD system served as ground work for following investigations. Poly(neopentyl methacrylate) (PnPMA) thin films were deposited with tert-butyl peroxide (TBPO) initiators and their Tg, CTE and thermal degradation properties were investigated. iCVD PnPMA films presented low-temperature degradation peaks attributed to weak linkages from H-abstraction and beta-scission reactions of TBPO. To test this hypothesis, PnPMA films were deposited with tert-butyl peroxybenzoate (TBPOB) which is selective towards vinyl addition. Contrary to expected results, TBPOB initiated films showed degradation at lower temperatures compared to TBPO initiated films. It is postulated that with TBPOB, the surface initiator concentration is higher and consequently small oligomeric molecules were formed that degraded easily. Following these investigations, poly

  19. High-speed deposition of titanium carbide coatings by laser-assisted metal–organic CVD

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Yansheng [Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074 (China); Tu, Rong, E-mail: turong@whut.edu.cn [State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Goto, Takashi [Institute for Materials Research, Tohoku University, Aoba-ku, 2-1-1 Katahira, Sendai 980-8577 (Japan)

    2013-08-01

    Graphical abstract: - Highlights: • A semiconductor laser was first used to prepare wide-area LCVD-TiC{sub x} coatings. • The effect of laser power for the deposition of TiC{sub x} coatings was discussed. • TiC{sub x} coatings showed a columnar cross section and a dense surface texture. • TiC{sub x} coatings had a 1–4 order lower laser density than those of previous reports. • This study gives the possibility of LCVD applying on the preparation of TiC{sub x} coating. - Abstract: A semiconductor laser-assisted chemical vapor deposition (LCVD) of titanium carbide (TiC{sub x}) coatings on Al{sub 2}O{sub 3} substrate using tetrakis (diethylamido) titanium (TDEAT) and C{sub 2}H{sub 2} as source materials were investigated. The influences of laser power (P{sub L}) and pre-heating temperature (T{sub pre}) on the microstructure and deposition rate of TiC{sub x} coatings were examined. Single phase of TiC{sub x} coatings were obtained at P{sub L} = 100–200 W. TiC{sub x} coatings had a cauliflower-like surface and columnar cross section. TiC{sub x} coatings in the present study had the highest R{sub dep} (54 μm/h) at a relative low T{sub dep} than those of conventional CVD-TiC{sub x} coatings. The highest volume deposition rate (V{sub dep}) of TiC{sub x} coatings was about 4.7 × 10{sup −12} m{sup 3} s{sup −1}, which had 3–10{sup 5} times larger deposition area and 1–4 order lower laser density than those of previous LCVD using CO{sub 2}, Nd:YAG and argon ion laser.

  20. CVD Method for Carbon Nanotubes Preparation Based on Orthogonal Experiment Using C3H6

    Institute of Scientific and Technical Information of China (English)

    SU Xunwen; JIANG Fang

    2015-01-01

    Carbon nanotubes (CNTs) have potential applications in many fields, chemical vapor deposition (CVD) is an effective method for CNTs preparation. By CVD, the catalytic pyrolysis temperature, pyrolysis time and the size of the raw gas lfow have a great inlfuence on yield rate of CNTs and their form. In this paper, the orthogonal experiment analysis method is used for studying the inlfuence factors of yield rate of CNTs. Research results show that, in the suitable temperature range of preparing CNTs, there is relatively more CNTs with excellent morphology, otherwise, if the temperature is too low, the growth of CNTs will not be sufifcient; if the temperature is too high, then CNTs will be generated with excessive defects; with longer growth time of suitable pyrolysis of CNTs, higher yield of CNTs will be obtained; CNTs morphology with reaction time is not proportional; too low or too high raw gas lfow rate is not conducive to the growth of CNTs. We have found the optimum conditions for the CNTs preparation: pyrolysis temperature 680℃, pyrolysis time 35 min, propylene lfow rate of 180 mL/min. The results have a reference value for the preparation of CNTS and their composites.

  1. High growth rate of a-SiC:H films using ethane carbon source by HW-CVD method

    Indian Academy of Sciences (India)

    Mahesh M Kamble; Vaishali S Waman; Sanjay S Ghosh; Azam Mayabadi; Vasant G Sathe; T Shripathi; Habib M Pathan; Sandesh R Jadkar

    2013-12-01

    Hydrogenated amorphous silicon carbide (a-SiC:H) thin films were prepared using pure silane (SiH4) and ethane (C2H6), a novel carbon source, without hydrogen dilution using hot wire chemical vapour deposition (HW-CVD) method at low substrate temperature (200 °C) and at reasonably higher deposition rate (19.5 Å/s < d < 35.2 Å/s). Formation of a-SiC:H films has been confirmed from FTIR, Raman and XPS analysis. Influence of deposition pressure on compositional, structural, optical and electrical properties has been investigated. FTIR spectroscopy analysis revealed that there is decrease in C–H and Si–H bond densities while, Si–C bond density increases with increase in deposition pressure. Total hydrogen content drops from 22.6 to 14.4 at.% when deposition pressure is increased. Raman spectra show increase in structural disorder with increase in deposition pressure. It also confirms the formation of nearly stoichiometric a-SiC:H films. Bandgap calculated using both Tauc’s formulation and absorption at 104 cm-1 shows decreasing trend with increase in deposition pressure. Decrease in refractive index and increase in Urbach energy suggests increase in structural disorder and microvoid density in the films. Finally, it has been concluded that C2H6 can be used as an effective carbon source in HW-CVD method to prepare stoichiometric a-SiC:H films.

  2. Drastically Enhanced High-Rate Performance of Carbon-Coated LiFePO4 Nanorods Using a Green Chemical Vapor Deposition (CVD) Method for Lithium Ion Battery: A Selective Carbon Coating Process.

    Science.gov (United States)

    Tian, Ruiyuan; Liu, Haiqiang; Jiang, Yi; Chen, Jiankun; Tan, Xinghua; Liu, Guangyao; Zhang, Lina; Gu, Xiaohua; Guo, Yanjun; Wang, Hanfu; Sun, Lianfeng; Chu, Weiguo

    2015-06-03

    Application of LiFePO4 (LFP) to large current power supplies is greatly hindered by its poor electrical conductivity (10(-9) S cm(-1)) and sluggish Li+ transport. Carbon coating is considered to be necessary for improving its interparticle electronic conductivity and thus electrochemical performance. Here, we proposed a novel, green, low cost and controllable CVD approach using solid glucose as carbon source which can be extended to most cathode and anode materials in need of carbon coating. Hydrothermally synthesized LFP nanorods with optimized thickness of carbon coated by this recipe are shown to have superb high-rate performance, high energy, and power densities, as well as long high-rate cycle lifetime. For 200 C (18s) charge and discharge, the discharge capacity and voltage are 89.69 mAh g(-1) and 3.030 V, respectively, and the energy and power densities are 271.80 Wh kg(-1) and 54.36 kW kg(-1), respectively. The capacity retention of 93.0%, and the energy and power density retention of 93.6% after 500 cycles at 100 C were achieved. Compared to the conventional carbon coating through direct mixing with glucose (or other organic substances) followed by annealing (DMGA), the carbon phase coated using this CVD recipe is of higher quality and better uniformity. Undoubtedly, this approach enhances significantly the electrochemical performance of high power LFP and thus broadens greatly the prospect of its applications to large current power supplies such as electric and hybrid electric vehicles.

  3. The optoelectronic properties of silicon films deposited by inductively coupled plasma CVD

    Energy Technology Data Exchange (ETDEWEB)

    Qin Yanli; Yan Hengqing; Li Fei; Qiao Li; Liu Qiming [Department of Physics, Lanzhou University, Lanzhou 730000 (China); He Deyan, E-mail: hedy@lzu.edu.cn [Department of Physics, Lanzhou University, Lanzhou 730000 (China)

    2010-11-15

    Hydrogenated amorphous and microcrystalline silicon films were deposited by inductively coupled plasma chemical vapor deposition (ICP-CVD) at low substrate temperatures using H{sub 2}-diluted SiH{sub 4} as a source gas. High-density plasma generated by inductively coupled excitation facilitates the crystallization of silicon films at low temperatures, and microcrystalline silicon films were obtained at the substrate temperature as low as 180 deg. C. The columnar structure of the films becomes more and more compact with an increase of their crystallinity. The reduction of hydrogen content in the films causes a narrowing of the optical bandgap and an enhancement of the absorption with increasing the substrate temperature. The microcrystalline silicon films show two electronic transport mechanisms: one is related to the density of state distribution in the temperature region near room temperature and the other is the variable range hopping between localized electronic states close to the Fermi level below 170 K. A reasonable explanation is presented for the dependence of the optoelectronic properties on the microstructure of the silicon films. The films prepared at a substrate temperature of 300 deg. C have highly crystalline and compact columnar structure, high optical absorption coefficient and electrical conductivity, and a low hydrogen content of 3.8%.

  4. Surface properties of diamond-like carbon films prepared by CVD and PVD methods

    Institute of Scientific and Technical Information of China (English)

    Liu Dong-Ping; Liu Yan-Hong; Chen Bao-Xiang

    2006-01-01

    Diamond-like carbon (DLC) films have been deposited using three different techniques: (a) electron cyclotron resonance-plasma source ion implantation, (b) low-pressure dielectric barrier discharge, (c) filtered-pulsed cathodic arc discharge. The surface and mechanical properties of these films are compared using atomic force microscopebased tests. The experimental results show that hydrogenated DLC films are covered with soft surface layers enriched with hydrogen and sp3 hybridized carbon while the soft surface layers of tetrahedral amorphous carbon (ta-C) films have graphite-like structure. The formation of soft surface layers can be associated with the surface diffusion and growth induced by the low-energy deposition process. For typical CVD methods, the atomic hydrogen in the plasmas can contribute to the formation of hydrogen and sp3 hybridized carbon enriched surface layers. The high-energy ion implantation causes the rearrangement of atoms beneath the surface layer and leads to an increase in film density. The ta-C films can be deposited using the medium energy carbon ions in the highly-ionized plasma.

  5. Hot wire CVD deposition of nanocrystalline silicon solar cells on rough substrates

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hongbo B.T., E-mail: h.li@uu.n [Utrecht University, Faculty of Science, Debye Institute for Nanomaterials Science, P.O. Box 80000, 3508 TA Utrecht (Netherlands); Werf, Karine H.M. van der; Rath, Jatin K.; Schropp, Ruud E.I. [Utrecht University, Faculty of Science, Debye Institute for Nanomaterials Science, P.O. Box 80000, 3508 TA Utrecht (Netherlands)

    2009-04-30

    In silicon thin film solar cell technology, frequently rough or textured substrates are used to scatter the light and enhance its absorption. The important issue of the influence of substrate roughness on silicon nanocrystal growth has been investigated through a series of nc-Si:H single junction p-i-n solar cells containing i-layers deposited with Hot-wire CVD. It is shown that silicon grown on the surface of an unoptimized rough substrate contains structural defects, which deteriorate solar cell performance. By introducing parameter v, voids/substrate area ratio, we could define a criterion for the morphology of light trapping substrates for thin film silicon solar cells: a preferred substrate should have a v value of less than around 1 x 10{sup -6}, correlated to a substrate surface rms value of lower than around 50 nm. Our Ag/ZnO substrates with rms roughness less than this value typically do not contain microvalleys with opening angles smaller than {approx} 110{sup o}, resulting in solar cells with improved output performance. We suggest a void-formation model based on selective etching of strained Si-Si atoms due to the collision of growing silicon film surface near the valleys of the substrate.

  6. Evaluating electrically insulating films deposited on V-4% Cr-4% Ti by reactive CVD

    Energy Technology Data Exchange (ETDEWEB)

    Park, J.H.; Cho, W.D. [Argonne National Lab., IL (United States)

    1997-04-01

    Previous CaO coatings on V-4%Cr-4%Ti exhibited high-ohmic insulator behavior even though a small amount of vanadium from the alloy was incorporated in the coating. However, when the vanadium concentration in the coatings is > 15 wt%, the coating becomes conductive. When the vanadium concentration is high in localized areas, a calcium vanadate phase that exhibits semiconductor behavior can form. To explore this situation, CaO and Ca-V-O coatings were produced on vanadium alloys by chemical vapor deposition (CVD) and by a metallic-vapor process to investigate the electrical resistance of the coatings. Initially, the vanadium alloy specimens were either charged with oxygen in argon that contained trace levels of oxygen, or oxidized for 1.5-3 h in a 1% CO-CO{sub 2} gas mixture or in air to form vanadium oxide at 625-650{degrees}C. Most of the specimens were exposed to calcium vapor at 800-850{degrees}C. Initial and final weights were obtained to monitor each step, and surveillance samples were removed for examination by optical and scanning electron microscopy and electron-energy-dispersive and X-ray diffraction analysis; the electrical resistivity was also measured. The authors found that Ca-V-O films exhibited insulator behavior when the ratio of calcium concentration to vanadium concentration R in the film was > 0.9, and semiconductor or conductor behavior for R < 0.8. However, in some cases, semiconductor behavior was observed when CaO-coated samples with R > 0.98 were exposed in liquid lithium. Based on these studies, the authors conclude that semiconductor behavior occurs if a conductive calcium vanadate phase is present in localized regions in the CaO coating.

  7. Synthesis of few-layer graphene on a Ni substrate by using DC plasma enhanced chemical vapor deposition (PE-CVD)

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jeong Hyuk; Castro, Edward Joseph; Hwang, Yong Gyoo; Lee, Choong Hun [Wonkwang University, Iksan (Korea, Republic of)

    2011-01-15

    In this work, few-layer graphene (FLG) was successfully grown on polycrystalline Ni a large scale by using DC plasma enhanced chemical vapor deposition (DC PE-CVD), which may serve as an alternative route in large-scale graphene synthesis. The synthesis time had an effect on the quality of the graphene produced. The applied DC voltage, on the other hand, influenced the minimization of the defect densities in the graphene grown. We also present a method of producing a free-standing polymethyl methacrylate (PMMA)/graphene membrane on a FeCl{sub 3(aq)} solution, which could then be transferred to the desired substrate.

  8. New CVD-based method for the growth of high-quality crystalline zinc oxide layers

    Science.gov (United States)

    Huber, Florian; Madel, Manfred; Reiser, Anton; Bauer, Sebastian; Thonke, Klaus

    2016-07-01

    High-quality zinc oxide (ZnO) layers were grown using a new chemical vapour deposition (CVD)-based low-cost growth method. The process is characterized by total simplicity, high growth rates, and cheap, less hazardous precursors. To produce elementary zinc vapour, methane (CH4) is used to reduce a ZnO powder. By re-oxidizing the zinc with pure oxygen, highly crystalline ZnO layers were grown on gallium nitride (GaN) layers and on sapphire substrates with an aluminum nitride (AlN) nucleation layer. Using simple CH4 as precursor has the big advantage of good controllability and the avoidance of highly toxic gases like nitrogen oxides. In photoluminescence (PL) measurements the samples show a strong near-band-edge emission and a sharp line width at 5 K. The good crystal quality has been confirmed in high resolution X-ray diffraction (HRXRD) measurements. This new growth method has great potential for industrial large-scale production of high-quality single crystal ZnO layers.

  9. Low temperature back-surface-field contacts deposited by hot-wire CVD for heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Munoz, D. [Universitat Politecnica de Catalunya, Grup de Recerca en Micro i Nanotecnologies, Jordi Girona 1-3, Barcelona 08034 (Spain)], E-mail: delfina@eel.upc.edu; Voz, C.; Martin, I.; Orpella, A.; Alcubilla, R. [Universitat Politecnica de Catalunya, Grup de Recerca en Micro i Nanotecnologies, Jordi Girona 1-3, Barcelona 08034 (Spain); Villar, F.; Bertomeu, J.; Andreu, J. [CeRMAE-Universitat de Barcelona, Departament de Fisica Aplicada i Optica, Diagonal 647, Barcelona 08028 (Spain); Roca-i-Cabarrocas, P. [LPICM-Ecole Polytechnique, CNRS 91128 Palaiseau (France)

    2008-08-30

    The growing interest in using thinner wafers (< 200 {mu}m) requires the development of low temperature passivation strategies for the back contact of heterojunction solar cells. In this work, we investigate low temperature deposited back contacts based on boron-doped amorphous silicon films obtained by Hot-Wire CVD. The influence of the deposition parameters and the use of an intrinsic buffer layer have been considered. The microstructure of the deposited thin films has been comprehensively studied by Spectroscopic Ellipsometry in the UV-visible range. The effective recombination velocity at the back surface has been measured by the Quasi-Steady-State Photoconductance technique. Complete double-side heterojunction solar cells (1 cm{sup 2}) have been fabricated and characterized by External Quantum Efficiency and current-voltage measurements. Total-area conversion efficiencies up to 14.5% were achieved in a fully low temperature process (< 200 deg. C)

  10. Field electron emission of diamond films on nanocrystalline diamond coating by CVD method

    Institute of Scientific and Technical Information of China (English)

    CAI Rangqi; CHEN Guanghua; SONG Xuemei; XING Guangjian; FENG Zhenjian; HE Deyan

    2003-01-01

    The preparation process, structure feature and field electron emission characteristic of diamond films on nanocyrstalline diamond coating by the CVD method were studied. The field electron emission measurements on the samples showed that the diamond films have lower turn-on voltage and higher field emission current density. A further detailed theory explanation to the results was given.

  11. Growth and Characterization of Silicon Carbide (SiC) Nanowires by Chemical Vapor Deposition (CVD) for Electronic Device Applications

    Science.gov (United States)

    Moore, Karina

    In recent years nanowires have gained a generous amount of interest because of the possible application of nanowires within electronic devices. A nanowire is a one dimensional semiconductor nanostructure with a diameter less than 100 nm. Nanowires have the potential to be a replacement for the present day complimentary metal oxide semiconductor (CMOS) technology; it is believed by 2020, a 5--6 nm gate length within field effect transistors (FET) would be realized and cease further miniaturization of electronic devices. SiC processes several unique chemical and physical properties that make it an attractive alternative to Si as a semiconductor material. Silicon carbide's properties make it a perfect candidate for applications such as high temperature sensors, x-ray emitters and high radiation sensors. The main objective of this thesis is to successfully grow silicon carbide nanowires on silicon substrates with the assistance of a metal catalyst, by the process of chemical vapor deposition (CVD). The contributions made by the work carried out in this thesis are broad. This is the first study that has carried out a comprehensive investigation into a wide range of metal catalyst for the growth of SiC nanowires by the process of chemical vapor deposition. The study proved that the surface tension interactions between the silicon substrate and the metal catalyst are the controlling factor in the determination of the diameter of the nanowires grown. This study also proved that the silicon substrate orientation has no impact on the growth of the nanowires, similar growth patterns occurred on both Si and Si substrates. The nanowires grown were characterized by a variety of different methods including scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS) and raman spectroscopy. The effect of temperature, growth temperature, growth time and the catalyst type used are investigated to determine the most suitable conditions necessary for SiC nanowire

  12. Structural and optical properties of tellurium films obtained by chemical vapor deposition(CVD)

    Institute of Scientific and Technical Information of China (English)

    MA Yu-tian; GONG Zhu-Qing; XU Wei-Hong; HUANG Jian

    2006-01-01

    Tellurium thin films were prepared by the chemical vapor deposition method. The structure, surface morphology and optical properties of the Te thin films were analyzed by powder X-ray diffraction, scanning electron microscopy, FTIR transmission,UV/VIS/NIR transmission and reflectance. The results show that the films structural and optical properties are influenced by many factors such as film thickness, crystallite size and substrate temperature. The films as thick as 111-133 nm have high IR transmission across the full 8-13 μm band and highly blocking in the solar spectral region elsewhere, which indicates that Te films thickness in this region can be used as good solar radiation shields in radiative cooling devices.

  13. Comparison of tungsten films grown by CVD and hot-wire assisted atomic layer deposition in a cold-wall reactor

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Mengdi, E-mail: M.Yang@utwente.nl; Aarnink, Antonius A. I.; Kovalgin, Alexey Y.; Gravesteijn, Dirk J.; Wolters, Rob A. M.; Schmitz, Jurriaan [MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands)

    2016-01-15

    In this work, the authors developed hot-wire assisted atomic layer deposition (HWALD) to deposit tungsten (W) with a tungsten filament heated up to 1700–2000 °C. Atomic hydrogen (at-H) was generated by dissociation of molecular hydrogen (H{sub 2}), which reacted with WF{sub 6} at the substrate to deposit W. The growth behavior was monitored in real time by an in situ spectroscopic ellipsometer. In this work, the authors compare samples with tungsten grown by either HWALD or chemical vapor deposition (CVD) in terms of growth kinetics and properties. For CVD, the samples were made in a mixture of WF{sub 6} and molecular or atomic hydrogen. Resistivity of the WF{sub 6}-H{sub 2} CVD layers was 20 μΩ·cm, whereas for the WF{sub 6}-at-H-CVD layers, it was 28 μΩ·cm. Interestingly, the resistivity was as high as 100 μΩ·cm for the HWALD films, although the tungsten films were 99% pure according to x-ray photoelectron spectroscopy. X-ray diffraction reveals that the HWALD W was crystallized as β-W, whereas both CVD films were in the α-W phase.

  14. Combined sonochemical/CVD method for preparation of nanostructured carbon-doped TiO2 thin film

    Science.gov (United States)

    Rasoulnezhad, Hossein; Kavei, Ghassem; Ahmadi, Kamran; Rahimipour, Mohammad Reza

    2017-06-01

    The present work reports the successful synthesis of the nanostructured carbon-doped TiO2 thin films on glass substrate by combination of chemical vapor deposition (CVD) and ultrasonic methods, for the first time. In this method the ultrasound waves act as nebulizer for converting of sonochemically prepared TiO2 sol to the mist particles. These mist particles were thermally decomposed in subsequent CVD chamber at 320 °C to produce the carbon-doped TiO2 thin films. The obtained thin films were characterized by means of X-ray Diffraction (XRD), Raman spectroscopy, diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and scanning electron microscopy (SEM) techniques. The results show that the prepared thin films have anatase crystal structure and nanorod morphology, which calcination of them at 800 °C results in the conversion of nanorods to nanoparticles. In addition, the prepared samples have high transparency, monodispersity and homogeneity. The presence of the carbon element in the structure of the thin films causes the narrowing of the band-gap energy of TiO2 to about 2.8 eV, which results in the improvement of visible light absorption capabilities of the thin film.

  15. Deposition rate and morphology of carbon nanotubes at different positions in a CVD reactor

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Carbon nanotubes (CNTs) were synthesized through the catalytic decomposition of a ferroeene-xylene mixture in a horizontal chemical vapor deposition reactor.The deposition rate of CNTs along the axial direction was measured.The morphology of CNTs was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM).The results showed that the deposition rate of CNTs along the axial direction first increased and later decreased,the position achieving the maximum deposition rate was influenced by the operating conditions.The morphologies of CNTs also changed along the axial direction.

  16. Filament poisoning at typical carbon nanotube deposition conditions by hot-filament CVD

    CSIR Research Space (South Africa)

    Oliphant, CJ

    2009-05-01

    Full Text Available This paper reports on the poisoning of tungsten filaments during the hot-filament chemical vapour deposition process at typical carbon nanotube (CNT) deposition conditions and filament temperatures ranging from 1400 to 2000 °C. The morphological...

  17. Field emissions of graphene films deposited on different substrates by CVD system

    Institute of Scientific and Technical Information of China (English)

    Wang Xiao-Ping; Liu Xiao-Fei; Liu Xin-Xin; Wang Li-Jun; Yang Can; Jing Long-Wei; Li Song-Kun; Pan Xiu-Fang

    2012-01-01

    Graphene films are deposited on copper (Cu) and aluminum (A1) substrates,respectively,by using a microwave plasma chemical vapour deposition technique.Furthermore,these graphene films are characterized by a field emission type scanning electron microscope (FE-SEM),Raman spectra,and field emission (FE) I-V measurements.It is found that the surface morphologies of the films deposited on Cu and Al substrates are different:the field emission property of graphene film deposited on the Cu substrate is better than that on the Al substrate,and the lowest turn-on field of 2.4 V/μm is obtained for graphene film deposited on the Cu substrate.The macroscopic areas of the graphene samples are all above 400 mm2.

  18. Structural and optical characterization of thick and thin polycrystalline diamond films deposited by microwave plasma activated CVD

    Indian Academy of Sciences (India)

    S K Pradhan; B Satpati; B P Bag; T Sharda

    2012-02-01

    Preliminary results of growth of thin diamond film in a recently installed 3 kW capacity microwave plasma activated CVD (MW-PACVD) system are being reported. The films were deposited on Si (100) substrate at 850°C using methane and hydrogen mixture at 1.5 kW MW power. The grown polycrystalline films were characterized by micro-Raman, transmission electron microscope (TEM), spectrophotometer and atomic force microscope (AFM). The results were compared with that of a thicker diamond film grown elsewhere in a same make MWPACVD system at relatively higher power densities. The presence of a sharp Raman peak at 1332 cm-1 confirmed the growth of diamond, and transmission spectra showed typical diamond film characteristics in both the samples. Typical twin bands and also a quintuplet twinned crystal were observed in TEM, further it was found that the twinned region in thin sample composed of very fine platelet like structure.

  19. Development Status of a CVD System to Deposit Tungsten onto UO2 Powder via the WCI6 Process

    Science.gov (United States)

    Mireles, O. R.; Kimberlin, A.; Broadway, J.; Hickman, R.

    2014-01-01

    Nuclear Thermal Propulsion (NTP) is under development for deep space exploration. NTP's high specific impulse (> 850 second) enables a large range of destinations, shorter trip durations, and improved reliability. W-60vol%UO2 CERMET fuel development efforts emphasize fabrication, performance testing and process optimization to meet service life requirements. Fuel elements must be able to survive operation in excess of 2850 K, exposure to flowing hydrogen (H2), vibration, acoustic, and radiation conditions. CTE mismatch between W and UO2 result in high thermal stresses and lead to mechanical failure as a result UO2 reduction by hot hydrogen (H2) [1]. Improved powder metallurgy fabrication process control and mitigated fuel loss can be attained by coating UO2 starting powders within a layer of high density tungsten [2]. This paper discusses the advances of a fluidized bed chemical vapor deposition (CVD) system that utilizes the H2-WCl6 reduction process.

  20. Effect of surface irradiation during the photo-CVD deposition of a-Si:H thin films. Hikari CVD ho ni yoru amorphous silicon sakuseiji no kiban hikari reiki koka

    Energy Technology Data Exchange (ETDEWEB)

    Tasaka, K.; Doering, H.; Hashimoto, K.; Fujishima, A. (The University of Tokyo, Tokyo (Japan))

    1990-12-06

    This paper shows the impact of the irradiation from an additional light source during the deposition of hydrogenated amorphous silicon by photo-CVD deposition. Using a mercury sensitized photo-CVD process from Disilan (Si {sub 2} H {sub 6}) and hydrogen, silicon was deposited. A 40W low pressure mercury lamp was applied as the light source. A portion of the substrate was in addition irradiated using an Xg-He lamp through a thermal filter. Irradiation of the substrate using only Xg-He lamp produced no deposition, since this light has a wavelength which is too long to produce the SiH {sub 3}-radicals needed for Si deposition. The additional Xg-He light source was discovered to cause an increased thickness of deposited a-Si:H film and a transmission of the band structure. The reasons of these are considered that the influence of irradiation is not limited to film thickness, but that irradiation also impacts the composition of the a-Si:H film so as to cause a reduction in the hydrogen content. 10 figs., 1 tab.

  1. Effect of PbI2 deposition rate on two-step PVD/CVD all-vacuum prepared perovskite

    Science.gov (United States)

    Ioakeimidis, Apostolos; Christodoulou, Christos; Lux-Steiner, Martha; Fostiropoulos, Konstantinos

    2016-12-01

    In this work we fabricate all-vacuum processed methyl ammonium lead halide perovskite by a sequence of physical vapour deposition of PbI2 and chemical vapour deposition (CVD) of CH3NH3I under a static atmosphere. We demonstrate that for higher deposition rate the (001) planes of PbI2 film show a higher degree of alignment parallel to the sample's surface. From X-ray diffraction data of the resulted perovskite film we derive that the intercalation rate of CH3NH3I is fostered for PbI2 films with higher degree of (001) planes alignment. The stoichiometry of the produced perovskite film is also studied by Hard X-ray photoelectron spectroscopy measurements. Complete all-vacuum perovskite solar cells were fabricated on glass/ITO substrates coated by an ultra-thin (5 nm) Zn-phthalocyanine film as hole selective layer. A dependence of residual PbI2 on the solar cells performance is displayed, while photovoltaic devices with efficiency up to η=11.6% were achieved.

  2. Silicon-Germanium Films Deposited by Low Frequency PE CVD: Effect of H2 and Ar Dilution

    Energy Technology Data Exchange (ETDEWEB)

    Kosarev, A; Torres, A; Hernandez, Y; Ambrosio, R; Zuniga, C; Felter, T E; Asomoza, R R; Kudriavtsev, Y; Silva-Gonzalez, R; Gomez-Barojas, E; Ilinski, A; Abramov, A S

    2005-09-22

    We have studied structure and electrical properties of Si{sub 1-Y}Ge{sub Y}:H films deposited by low frequency PE CVD over the entire composition range from Y=0 to Y=1. The deposition rate of the films and their structural and electrical properties were measured for various ratios of the germane/silane feed gases and with and without dilution by Ar and by H{sub 2}. Structure and composition was studied by Auger electron spectroscopy (AES), secondary ion mass spectroscopy (SIMS) and Fourier transform infrared (FTIR) spectroscopy. Surface morphology was characterized by atomic force microscopy (AFM). We found: (1) The deposition rate increased with Y maximizing at Y=1 without dilution. (2) The relative rate of Ge and Si incorporation is affected by dilution. (3) Hydrogen preferentially bonds to silicon. (4) Hydrogen content decreases for increasing Y. In addition, optical measurements showed that as Y goes for 0 to 1, the Fermi level moves from mid gap to the conduction band edge, i.e. the films become more n-type. No correlation was found between the pre-exponential and the activation energy of conductivity. The behavior of the conductivity {gamma}-factor suggests a local minimum in the density of states at E {approx} 0.33 eV for the films grown with or without H-dilution and E {approx} 0.25 eV for the films with Ar dilution.

  3. Influence of deposition rate on the structural properties of plasma-enhanced CVD epitaxial silicon

    Science.gov (United States)

    Chen, Wanghua; Cariou, Romain; Hamon, Gwenaëlle; Léal, Ronan; Maurice, Jean-Luc; Cabarrocas, Pere Roca i

    2017-01-01

    Solar cells based on epitaxial silicon layers as the absorber attract increasing attention because of the potential cost reduction. In this work, we studied the influence of the deposition rate on the structural properties of epitaxial silicon layers produced by plasma-enhanced chemical vapor deposition (epi-PECVD) using silane as a precursor and hydrogen as a carrier gas. We found that the crystalline quality of epi-PECVD layers depends on their thickness and deposition rate. Moreover, increasing the deposition rate may lead to epitaxy breakdown. In that case, we observe the formation of embedded amorphous silicon cones in the epi-PECVD layer. To explain this phenomenon, we develop a model based on the coupling of hydrogen and built-in strain. By optimizing the deposition conditions to avoid epitaxy breakdown, including substrate temperatures and plasma potential, we have been able to synthesize epi-PECVD layers up to a deposition rate of 8.3 Å/s. In such case, we found that the incorporation of hydrogen in the hydrogenated crystalline silicon can reach 4 at. % at a substrate temperature of 350 °C. PMID:28262840

  4. The effects of flow multiplicity on GaN deposition in a rotating disk CVD reactor

    Science.gov (United States)

    Gkinis, P. A.; Aviziotis, I. G.; Koronaki, E. D.; Gakis, G. P.; Boudouvis, A. G.

    2017-01-01

    The effect of gas flow multiplicity, i.e. the possibility of two very different flow regimes prevailing at random in a rotating disk metalorganic chemical vapor deposition (MOCVD) reactor, on the deposited GaN film is investigated. A transport model coupled with a system of chemical reactions in the gas phase and on the wafer where the film is formed, is implemented in the parameter regions where multiple flows are possible. In the region of multiplicity where either plug flow, imposed by forced convection, or buoyancy-dominated flow is possible, the results in the latter case indicate high deposition rate and decreased uniformity. In the former case, increasing the pressure and the rotation rate has a favorable effect on the deposition rate without sacrificing uniformity. In the parameter window of multiplicity where either rotation or combined rotation/buoyancy may prevail, the effects of buoyancy lead to higher deposition rate at the center of the wafer and reduced uniformity. The Arrhenius plots in the regions of multiplicity for exactly the same operating conditions reveal that the system operates in a diffusion-limited regime in the plug flow and in the rotation-dominated flow, in the first and second region of multiplicity respectively. In contrast, in the buoyancy-dominated flow and the combined rotation/buoyancy flow (first and second region of multiplicity respectively) the process shifts into the kinetics-limited regime.

  5. TiAlN and TiAlCN deposition in an industrial PaCVD-plant

    Energy Technology Data Exchange (ETDEWEB)

    Heim, D.; Hochreiter, R. [Ruebig GmbH, Co., Wels (Austria)

    1998-01-01

    An industrial PaCVD-plant was equipped with an AlCl{sub 3}-generator. By using Ar, H{sub 2}, N{sub 2}, CH{sub 4}, TiCl{sub 4} and AlCl{sub 3}, TiAlN- and TiAlCN-films could be deposited on hard metal and steel substrates. The plasma was generated by a DC-pulse power supply with frequencies up to 50 kHz. The reactor size was 350 mm in diameter and 900 mm in height. During one batch 1200 indexable inserts could be coated. The growth rates were about 1-3 {mu}m h{sup -1}. The deposited films show a fine structure and Cl-concentrations below 3%. The measured critical loads were between 30 and 40 N. Wear test results show an increase in tool life up to several 100% compared with uncoated or TiN-coated tools. (orig.) 7 refs.

  6. Initiated Chemical Vapor Deposition (iCVD) of Highly Cross-Linked Polymer Films for Advanced Lithium-Ion Battery Separators.

    Science.gov (United States)

    Yoo, Youngmin; Kim, Byung Gon; Pak, Kwanyong; Han, Sung Jae; Song, Heon-Sik; Choi, Jang Wook; Im, Sung Gap

    2015-08-26

    We report an initiated chemical vapor deposition (iCVD) process to coat polyethylene (PE) separators in Li-ion batteries with a highly cross-linked, mechanically strong polymer, namely, polyhexavinyldisiloxane (pHVDS). The highly cross-linked but ultrathin pHVDS films can only be obtained by a vapor-phase process, because the pHVDS is insoluble in most solvents and thus infeasible with conventional solution-based methods. Moreover, even after the pHVDS coating, the initial porous structure of the separator is well preserved owing to the conformal vapor-phase deposition. The coating thickness is delicately controlled by deposition time to the level that the pore size decreases to below 7% compared to the original dimension. The pHVDS-coated PE shows substantially improved thermal stability and electrolyte wettability. After incubation at 140 °C for 30 min, the pHVDS-coated PE causes only a 12% areal shrinkage (versus 90% of the pristine separator). The superior wettability results in increased electrolyte uptake and ionic conductivity, leading to significantly improved rate performance. The current approach is applicable to a wide range of porous polymeric separators that suffer from thermal shrinkage and poor electrolyte wetting.

  7. Diamond like carbon coatings deposited by microwave plasma CVD: XPS and ellipsometric studies

    Indian Academy of Sciences (India)

    R M Dey; M Pandey; D Bhattacharyya; D S Patil; S K Kulkarni

    2007-12-01

    Diamond-like carbon (DLC) films were deposited by microwave assisted chemical vapour deposition system using d.c. bias voltage ranging from –100 V to –300 V. These films were characterized by X-ray photoelectron spectroscopy (XPS) and spectroscopic ellipsometry techniques for estimating 3/2 ratio. The 3/2 ratio obtained by XPS is found to have an opposite trend to that obtained by spectroscopic ellipsometry. These results are explained using sub-plantation picture of DLC growth. Our results clearly indicate that the film is composed of two different layers, having entirely different properties in terms of void percentage and 3/2 ratio. The upper layer is relatively thinner as compared to the bottom layer.

  8. The Formation of Nanocrystalline Diamond Coating on WC Deposited by Microwave Assisted Plasma CVD

    Science.gov (United States)

    Toff, M. R. M.; Hamzah, E.; Purniawan, A.

    2010-03-01

    Diamond is one form of carbon structure. The extreme hardness and high chemical resistant of diamond coatings determined that many works on this area relate to coated materials for tribological applications in biomedicine, as mechanical seals or cutting tools for hard machining operations. In the work, nanocrystalline diamond (NCD) coated tungsten carbide (WC) have been deposited by microwave assisted plasma chemical vapor deposition (MAPCVD) from CH4/H2 mixtures. Morphology of NCD was investigated by using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The quality of NCD is defined as ratio between diamond and non diamond and also full width at half maximum (FWHM) was determined using Raman spectra. The result found that the NCD structure can be deposited on WC surface using CH4/H2 gas mixture with grain size ˜20 nm to 100 nm. Increase %CH4 concentration due to increase the nucleation of NCD whereas decrease the quality of diamond. Based on Raman spectra, the quality of NCD is in the range ˜98.82-99.01% and 99.56-99.75% for NCD and microcrystalline (MCD), respectively. In addition, FWHM of NCD is high than MCD in the range of 8.664-62.24 cm-1 and 4.24-5.05 cm-1 for NCD and MCD respectively that indicate the crystallineity of NCD is smaller than MCD.

  9. Novel Gas Barrier SiOC Coating to PET Bottles through a Hot Wire CVD Method

    Directory of Open Access Journals (Sweden)

    Masaki Nakaya

    2016-01-01

    Full Text Available In an attempt to enhance the gas barrier enhancement of plastic containers such as poly(ethylene terephthalate bottles, a novel method was found using a hot wire CVD technique, where tantalum wire is heated and exposed to a gas flow of vinyl silane. The resultant SiOC thin film was confirmed to characteristically contain Si-Si bonds in its surface and demonstrate a remarkably and highly practical decrease of the permeation of various gas through poly(ethylene terephthalate bottles.

  10. The effectiveness of Ti implants as barriers to carbon diffusion in Ti implanted steel under CVD diamond deposition conditions

    Energy Technology Data Exchange (ETDEWEB)

    Weiser, P.S.; Prawer, S. [Melbourne Univ., Parkville, VIC (Australia). School of Physics; Hoffman, A. [Technion-Israel Inst. of Tech., Haifa (Israel). Dept. of Chemistry; Evan, P.J. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Paterson, P.J.K. [Royal Melbourne Inst. of Tech., VIC (Australia)

    1993-12-31

    The growth of chemical vapour deposited (CVD) diamond onto iron based substrates complicated by preferential soot formation and carbon diffusion into the substrate [1], leading to poor quality films and poor adhesion. In the initial stages of exposure to a microwave plasma, a layer of graphite is rapidly formed on an untreated Fe based substrate. Once this graphite layer reaches a certain thickness, reasonable quality diamond nucleates and grows upon it. However, the diamond film easily delaminates from the substrate, the weak link being the graphitic layer. Following an initial success in using a TiN barrier layer to inhibit the formation of such a graphitic layer the authors report on attempts to use an implanted Ti layer for the same purpose. This work was prompted by observation that, although the TiN proved to be an extremely effective diffusion barrier, adhesion may be further enhanced by the formation of a TiC interface layer between the diamond film and the Fe substrate. 3 refs., 6 figs.

  11. Interlayer utilization (including metal borides) for subsequent deposition of NSD films via microwave plasma CVD on 316 and 440C stainless steels

    Science.gov (United States)

    Ballinger, Jared

    . Surface boriding was implemented using the novel method of microwave plasma CVD with a mixture of hydrogen and diborane gases. On 440C bearings, dual phase boride layers of Fe2B and FeB were formed which supported adhered nanostructured diamond films. Continuity of the films was not seamless with limited regions remaining uncoated potentially corresponding to delamination of the film as evidenced by the presence of tubular structures presumably composed of sp2 bonded carbon. Surface boriding of 316 stainless steel discs was conducted at various powers and pressures to achieve temperatures ranging from 550-800 °C. The substrate boriding temperature was found to substantially influence the resultant interlayer by altering the metal boride(s) present. The lowest temperatures produced an interlayer where CrB was the single detected phase, higher temperatures yielded the presence of only Fe2B, and a combination of the two phases resulted from an intermediate boriding temperature. Compared with the more common, commercialized boriding methods, this a profound result given the problems posed by the FeB phase in addition to other advantages offered by CVD processes and microwave generated plasmas in general. Indentation testing of the boride layers revealed excellent adhesion strength for all borided interlayers, and above all, no evidence of cracking was observed for a sole Fe2B phase. As with boriding of 440C bearings, subsequent diamond deposition was achieved on these interlayers with substantially improved adhesion strength relative to diamond coated TiN interlayers. Both XRD and Raman spectroscopy confirmed a nanostructured diamond film with interfacial chromium carbides responsible for enhanced adhesion strength. Interlayers consisting solely of Fe2B have displayed an ability to support fully continuous nanostructured diamond films, yet additional study is required for consistent reproduction. This is in good agreement with initial work on pack borided high alloy steels

  12. Investigation of phonon modes in gallium nitride nanowires deposited by thermal CVD

    Energy Technology Data Exchange (ETDEWEB)

    Rizal, Umesh, E-mail: umeshrizal680@gmail.com; Swain, Bibhu P., E-mail: bibhu.s@smit.smu.edu.in [Nano Processing Laboratory, Centre for Material Science and Nanotechnology, Sikkim Manipal Institute of Technology, Majitar, Rangpo, East Sikkim, India-737136 (India); Swain, Bhabani S., E-mail: bsswain@kookmin.ac.kr [School of Advanced Materials Engineering, Kookmin University, Sungbuk-gu, Jeongnung-dong, Seoul (Korea, Republic of)

    2016-04-13

    Gallium nitride nanowires (GaN-NWs) of diameters ranging from 20 to 80 nm were grown on the p-type Si substrate by Thermal Chemical Vapor Deposition (TCVD) using Iron (Fe) catalyst via VLS mechanism. Raman and FTIR spectra reveal the presence of broad transverse optic (TO) and longitudinal optic (LO) phonon peak spreads over 500-600 cm{sup −1} and 720 cm{sup −1} respectively. The detail deconvolution of integrated transverse and longitudinal phonon analysis reveals phonon confinement brought out by incorporation of hydrogen atom. The red shifts of TO and LO phonon peak position indicates nanosized effect. I{sub A1(LO)}/I{sub A1(TO)} increases from 0.073 to 1.0 and their respective fwhm{sub A1(LO)}/fwhm{sub A1(TO)} also increases from 0.71 to 1.31 with increasing H{sub 2} flow rate. E{sub 1}(LO) - E{sub 1}(TO) and A{sub 1}(LO) - A{sub 1}(TO) increases from 173.83 to 190.73 and 184.89 to 193.22 respectively. Apart from this usual TO and LO phonon, we have found Surface Optic (SO) phonon at 671 cm{sup −1} in FTIR spectra. The intensity of PL peak increases with increasing H{sub 2} dilution reveals efficient passivation of defect centre at surface of GaN-NWs.

  13. The deposition characteristics of copper(I) compounds for CVD by FT-IR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hardcastle, F.D.; Peden, C.H.F.; Omstead, T.R.; Blewer, R.S. [Sandia National Labs., Albuquerque, NM (United States); Farkas, J.; Hampden-Smith, M.J.; Kodas, T.T. [New Mexico Univ., Albuquerque, NM (United States)

    1991-12-31

    Fourier transform-infrared spectroscopy (FT-IR) was used to investigate the adsorption and thermally-induced decomposition of copper (I) {beta}-diketonate precursors of the type (hfac)CuL, where hfac is the hexafluoroacetylacetonate bidentate ligand and L is trimethylphosphine or 1,5-cyclooctadiene. The (hfac)CuPMe{sub 3} precursor desorbs from the surface at very low temperatures whereas the (hfac)Cu(1,5-COD) dissociates on adsorption, liberating 1,5-COD and leaving a surface(hfac)Cu complex which can subsequently disproportionate. Evidence is provided for hydrogen-bonding between the hfac ligand and the surface silanols for (hfac)CuPMe{sub 3}, but not for (hfac)Cu(1,5-COD). These results are consistent with the selective behavior of these precursors for copper deposition and suggest that the selectivity of the (hfac)CuPMe{sub 3} and (hfac)Cu(1, 5-COD) precursors may be due to the ability of the hfac ligand to hydrogen bond to the surface silanol groups.

  14. The deposition characteristics of copper(I) compounds for CVD by FT-IR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hardcastle, F.D.; Peden, C.H.F.; Omstead, T.R.; Blewer, R.S. (Sandia National Labs., Albuquerque, NM (United States)); Farkas, J.; Hampden-Smith, M.J.; Kodas, T.T. (New Mexico Univ., Albuquerque, NM (United States))

    1991-01-01

    Fourier transform-infrared spectroscopy (FT-IR) was used to investigate the adsorption and thermally-induced decomposition of copper (I) {beta}-diketonate precursors of the type (hfac)CuL, where hfac is the hexafluoroacetylacetonate bidentate ligand and L is trimethylphosphine or 1,5-cyclooctadiene. The (hfac)CuPMe{sub 3} precursor desorbs from the surface at very low temperatures whereas the (hfac)Cu(1,5-COD) dissociates on adsorption, liberating 1,5-COD and leaving a surface(hfac)Cu complex which can subsequently disproportionate. Evidence is provided for hydrogen-bonding between the hfac ligand and the surface silanols for (hfac)CuPMe{sub 3}, but not for (hfac)Cu(1,5-COD). These results are consistent with the selective behavior of these precursors for copper deposition and suggest that the selectivity of the (hfac)CuPMe{sub 3} and (hfac)Cu(1, 5-COD) precursors may be due to the ability of the hfac ligand to hydrogen bond to the surface silanol groups.

  15. Method of Monitoring the Corrosion Behavior the Surface Treated FMS and CVD Coated Specimen in Liquid Sodium Environment

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jeong Hyeon; Shin, Sang Hun; Kim, Ji Hyun [UNIST, Ulsan (Korea, Republic of)

    2014-10-15

    Gr.92 and HT9 (Ferritic/martensitic steels) are considered as candidates of cladding materials of Sodium-cooled Fast Reactors (SFRs). HT9 and Gr.92 are known as compatible in sodium environment because the usual refueling time of SFRs is designed about 54 months. In the Ultra-long Cycle Fast Reactor (UCFR) which is developed in UNIST, however, cladding is exposed long-term in high temperature liquid sodium environment. So, it is very important to investigate the corrosion-related behavior such as surface corrosion rate, carburization, decarburization and mechanical properties for its operation time. The decarburization process where dissolved carbon near the specimen surface diffused in to the liquid sodium. This process can originate from the difference between dissolved carbon activity in the material and liquid sodium. A compatibility test the cladding tube revealed that a decrease of the mechanical property instigated by the aging proves governed the whole mechanical property. SiC and Si3N4 Chemical Vapor Deposition (CVD) coating for decarburization barrier on the surface of FMS is considered in this study. The CVD coated specimens are experiment for compatibility of high temperature liquid sodium. To monitor the corrosion behavior of these candidate materials in sodium environment, Electrochemical Impedance Spectroscopy (EIS) method is first introduced and investigated in this study. The use of the technique of impedance spectroscopy to measure the electrical impedance response of any oxide layers, SiC and Si{sub 3}N{sub 4} that may be present may be a solution to this monitoring problem.

  16. Preparation of born-doped a-SiC:H thin films by ICP-CVD method and to the application of large-area heterojunction solar cells.

    Science.gov (United States)

    Jeong, Chaehwan; Kim, Young-Back; Lee, Suk-Ho; Kim, Jin Hyeok

    2010-05-01

    Hydrogenated amorphous silicon carbide (a-SiC:H) film has been widely used as an emitter p layer in solar cells. For the better p layer, wide optical bandgap, and high electrical conductivity should be obtained from the effective method. We prepared the boron-doped a-SiC:H thin films using inductively coupled plasma chemical vapor deposition (ICP-CVD) method and characteristics on the small-area (2 cm x 2 cm) as well as the large-area films (diameter of 100 mm) were shown on it. As a substrate, the n-type (100) oriented CZ c-Si (5.5 approximately 6.5 omega x cm, 650 microm) wafers were used and cleaned by using the reduced RCA method. A silane (SiH4) of 99.999% purity, H2 and 60% hydrogen diluted ethylene (C2H4) was used as source gas for the deposition of intrinsic a-SiC:H films, and then diborane (B2H6), as the doping gas, is added to C2H4 and SiH4/H2 during the deposition of films. The uniformity of thickness and optical bandgap from large-area as-dep. films was at 1.8% and 0.3%, respectively. Heterojunction solar cell with 2 wt%-AZO/p-a-SiC:H/i-a-Si:H/c-Si/Ag structure was fabricated and characterized with diameter of 152.3 mm in this large-area ICP-CVD system. Conversion efficiency of 9.123% was achieved with a practical area of 100 mm x 100 mm, which can show the potentials to the fabrication of the large-area solar cell using ICP-CVD method.

  17. Fabrication of Fe nanowires on yittrium-stabilized zirconia single crystal substrates by thermal CVD methods

    Energy Technology Data Exchange (ETDEWEB)

    Kawahito, A. [Graduate School of Chemical Science and Engineering, Hokkaido University, Kita-ku, Sapporo 060-8628 (Japan); Yanase, T. [Frontier Chemistry Center, Faculty of Engineering, Hokkaido University, Kita-ku, Sapporo 060-8628 (Japan); Endo, T.; Nagahama, T.; Shimada, T., E-mail: shimadat@eng.hokudai.ac.jp [Faculty of Engineering, Hokkaido University, Kita-ku, Sapporo 060-8628 (Japan)

    2015-05-07

    Magnetic nanowires (NWs) are promising as material for use in spintronics and as the precursor of permanent magnets because they have unique properties due to their high aspect ratio. The growth of magnetic Fe whiskers was reported in the 1960s, but the diameter was not on a nanoscale level and the growth mechanism was not fully elucidated. In the present paper, we report the almost vertical growth of Fe NWs on a single crystal yttrium-stabilized zirconia (Y{sub 0.15}Zr{sub 0.85}O{sub 2}) by a thermal CVD method. The NWs show a characteristic taper part on the bottom growing from a trigonal pyramidal nucleus. The taper angle and length can be controlled by changing the growth condition in two steps, which will lead to obtaining uniformly distributed thin Fe NWs for applications.

  18. Fabrication of Fe nanowires on yittrium-stabilized zirconia single crystal substrates by thermal CVD methods

    Science.gov (United States)

    Kawahito, A.; Yanase, T.; Endo, T.; Nagahama, T.; Shimada, T.

    2015-05-01

    Magnetic nanowires (NWs) are promising as material for use in spintronics and as the precursor of permanent magnets because they have unique properties due to their high aspect ratio. The growth of magnetic Fe whiskers was reported in the 1960s, but the diameter was not on a nanoscale level and the growth mechanism was not fully elucidated. In the present paper, we report the almost vertical growth of Fe NWs on a single crystal yttrium-stabilized zirconia (Y0.15Zr0.85O2) by a thermal CVD method. The NWs show a characteristic taper part on the bottom growing from a trigonal pyramidal nucleus. The taper angle and length can be controlled by changing the growth condition in two steps, which will lead to obtaining uniformly distributed thin Fe NWs for applications.

  19. Analysis of Residual Thermal Stress in CVD-W Coating as Plasma Facing Material

    Institute of Scientific and Technical Information of China (English)

    朱大焕; 王坤; 王先平; 陈俊凌; 方前锋

    2012-01-01

    Chemical vapor deposition-tungsten (CVD-W) coating covering the surface of the plasma facing component (PFC) is an effective method to implement the tungsten material as plasma facing material (PFM) in fusion devices. Residual thermal stress in CVD-W coating due to thermal mismatch between coating and substrate was successfully simulated by using a finite element method (ANSYS 10.0 code). The deposition parametric effects, i.e., coating thickness and deposition temperature, and interlayer were investigated to get a description of the residual thermal stress in the CVD-W coating-substrate system. And the influence of the substrate materials on the generation of residual thermal stress in the CVD-W coating was analyzed with respect to the CVD-W coating application as PFM. This analysis is beneficial for the preparation and application of CVD-W coating.

  20. Analysis of Residual Thermal Stress in CVD-W Coating as Plasma Facing Material

    Science.gov (United States)

    Zhu, Dahuan; Wang, Kun; Wang, Xianping; Chen, Junling; Fang, Qianfeng

    2012-07-01

    Chemical vapor deposition-tungsten (CVD-W) coating covering the surface of the plasma facing component (PFC) is an effective method to implement the tungsten material as plasma facing material (PFM) in fusion devices. Residual thermal stress in CVD-W coating due to thermal mismatch between coating and substrate was successfully simulated by using a finite element method (ANSYS 10.0 code). The deposition parametric effects, i.e., coating thickness and deposition temperature, and interlayer were investigated to get a description of the residual thermal stress in the CVD-W coating-substrate system. And the influence of the substrate materials on the generation of residual thermal stress in the CVD-W coating was analyzed with respect to the CVD-W coating application as PFM. This analysis is beneficial for the preparation and application of CVD-W coating.

  1. Plasma-Enhanced Chemical Vapor Deposition (PE-CVD) yields better Hydrolytical Stability of Biocompatible SiOx Thin Films on Implant Alumina Ceramics compared to Rapid Thermal Evaporation Physical Vapor Deposition (PVD).

    Science.gov (United States)

    Böke, Frederik; Giner, Ignacio; Keller, Adrian; Grundmeier, Guido; Fischer, Horst

    2016-07-20

    Densely sintered aluminum oxide (α-Al2O3) is chemically and biologically inert. To improve the interaction with biomolecules and cells, its surface has to be modified prior to use in biomedical applications. In this study, we compared two deposition techniques for adhesion promoting SiOx films to facilitate the coupling of stable organosilane monolayers on monolithic α-alumina; physical vapor deposition (PVD) by thermal evaporation and plasma enhanced chemical vapor deposition (PE-CVD). We also investigated the influence of etching on the formation of silanol surface groups using hydrogen peroxide and sulfuric acid solutions. The film characteristics, that is, surface morphology and surface chemistry, as well as the film stability and its adhesion properties under accelerated aging conditions were characterized by means of X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), inductively coupled plasma-optical emission spectroscopy (ICP-OES), and tensile strength tests. Differences in surface functionalization were investigated via two model organosilanes as well as the cell-cytotoxicity and viability on murine fibroblasts and human mesenchymal stromal cells (hMSC). We found that both SiOx interfaces did not affect the cell viability of both cell types. No significant differences between both films with regard to their interfacial tensile strength were detected, although failure mode analyses revealed a higher interfacial stability of the PE-CVD films compared to the PVD films. Twenty-eight day exposure to simulated body fluid (SBF) at 37 °C revealed a partial delamination of the thermally deposited PVD films whereas the PE-CVD films stayed largely intact. SiOx layers deposited by both PVD and PE-CVD may thus serve as viable adhesion-promoters for subsequent organosilane coupling agent binding to α-alumina. However, PE-CVD appears to be favorable for long-term direct film exposure to aqueous

  2. Diagnosis of gas phase near the substrate surface in diamond film deposition by high-power DC arc plasma jet CVD

    Institute of Scientific and Technical Information of China (English)

    Zuyuan Zhou; Guangchao Chen; Bin Li; Weizhong Tang; Fanxiu Lv

    2007-01-01

    Optical emission spectroscopy (OES) was used to study the gas phase composition near the substrate surface during diamond deposition by high-power DC arc plasma jet chemical vapor deposition (CVD). C2 radical was determined as the main carbon radical in this plasma atmosphere. The deposition parameters, such as substrate temperature, anode-substrate distance, methane concentration, and gas flow rate, were inspected to find out the influence on the gas phase. A strong dependence of the concentrations and distribution of radicals on substrate temperature was confirmed by the design of experiments (DOE). An explanation for this dependence could be that radicals near the substrate surface may have additional ionization or dissociation and also have recombination,or are consumed on the substrate surface where chemical reactions occur.

  3. CVD polymers fabrication of organic surfaces and devices

    CERN Document Server

    Gleason, Karen K

    2015-01-01

    The method of CVD (chemical vapor deposition) is a versatile technique to fabricate high-quality thin films and structured surfaces in the nanometer regime from the vapor phase. Already widely used for the deposition of inorganic materials in the semiconductor industry, CVD has become the method of choice in many applications to process polymers as well. This highly scalable technique allows for synthesizing high-purity, defect-free films and for systematically tuning their chemical, mechanical and physical properties. In addition, vapor phase processing is critical for the deposition of insol

  4. Hydrogenated Silicon Carbide Thin Films Prepared with High Deposition Rate by Hot Wire Chemical Vapor Deposition Method

    Directory of Open Access Journals (Sweden)

    M. M. Kamble

    2014-01-01

    Full Text Available Structural, optical, and electrical properties of hydrogenated silicon carbide (SiC:H films, deposited from silane (SiH4 and methane (CH4 gas mixture by HW-CVD method, were investigated. Film properties are carefully and systematically studied as function of deposition pressure which is varied between 200 mTorr and 500 mTorr. The deposition rate is found to be reasonably high (9.4 nm/s deposition pressure amorphization occurs in SiC:H films. FTIR spectroscopy analysis shows that bond density of C–H decreases while Si–C and Si–H bond densities increase with increasing deposition pressure. Total hydrogen content increases with increasing deposition pressure and was found to be <20 at.%. The absence of band ~1300–1600 cm−1 in the Raman spectra implies negligible C–C bond concentration and formation of nearly stoichiometric SiC:H films. The band gap shows increasing trend with increasing deposition pressure. The high value of Urbach energy suggests increased structural disorder in SiC:H films. Finally, it has been concluded that CH4 can be used as effective carbon source in HW-CVD method to prepare stoichiometric SiC:H films.

  5. Production of Carbon Nanofibers Using a CVD Method with Lithium Fluoride as a Supported Cobalt Catalyst

    Directory of Open Access Journals (Sweden)

    S. A. Manafi

    2008-02-01

    Full Text Available Carbon nanofibers (CNFs have been synthesized in high yield (>70% by catalytic chemical vapor deposition (CCVD on Co/LiF catalyst using acetylene as carbon source. A novel catalyst support (LiF is reported for the first time as an alternative for large-scale production of carbon nanofibers while purification process of nanofibers is easier. In our experiment, the sealed furnace was heated at 700∘C for 0.5 hour (the heating rate was 10∘C/min and then cooled to room temperature in the furnace naturally. Catalytic chemical vapor deposition is of interest for fundamental understanding and improvement of commercial synthesis of carbon nanofibers (CNFs. The obtained sample was sequentially washed with ethanol, dilutes acid, and distilled water to remove residual impurities, amorphous carbon materials, and remaining of catalyst, and then dried at 110∘C for 24 hours. The combined physical characterization through several techniques, such as high-resolution transmission electron microscope (TEM, scanning electron microscope (SEM, thermogarvimetric analysis (TGA, and zeta-sizer and Raman spectroscopy, allows determining the geometric characteristic and the microstructure of individual carbon nanofibers. Catalytic chemical vapor deposition is of interest for fundamental understanding and improvement of commercial synthesis of carbon nanofibers (CNFs. As a matter of fact, the method of CCVD guarantees the production of CNFs for different applications.

  6. AFM Morphology Study of Si1-Y GeY:H Films Deposited by LF PE CVD from Silane-Germane with Different

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, L; Kosarev, A

    2005-03-28

    The morphology of Si{sub 1-Y} Ge{sub Y}:H films in the range of Y=0.23 to 0.9 has been studied by AFM. The films were deposited by Low Frequency (LF) PE CVD at substrate temperature T{sub s}=300 C and discharge frequency f=110 kHz from silane+germane mixture with and without, Ar and H{sub 2} dilution. The films were deposited on silicon and glass substrates. AFM images were taken and analyzed for 2 x 2 mm{sup 2} area. All the images demonstrated ''grain'' like structure, which was characterized by the height distribution function F(H) average roughness , standard height deviation Rq, lateral correlation length L{sub c} area distribution function F(s), mean grain area , diameter distribution function F(d), and mean grain diameter . The roughness of the films monotonically increases with Y for all dilutions, but more significantly in the films deposited without dilution. L{sub c} continuously grows with Y in the films deposited without dilution, while more complex behavior L{sub c}(Y) is observed in the films deposited with H- or Ar dilution. The sharpness of F(H) characterized by curtosis {gamma} depends on dilution and the sharpest F(H) are for the films deposited with Ar ({gamma}=5.30,Y=0.23) and without dilution ({gamma}=4.3, Y=0.45). Isothermal annealing caused increase of , L{sub c} in the films deposited with H- and Ar dilutions, while in the films prepared without dilution the behavior was more complex, depending on the substrates. Significant narrowing of the height distribution was observed in the films deposited with H dilution or without dilution.

  7. Molecular fouling resistance of zwitterionic and amphiphilic initiated chemically vapor-deposited (iCVD) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Yang, R; Goktekin, E; Wang, MH; Gleason, KK

    2014-08-08

    Biofouling is a universal problem in various applications ranging from water purification to implantable biomedical devices. Recent advances in surface modification have created a rich library of antifouling surface chemistries, many of which can be categorized into one of the two groups: hydrophilic surfaces or amphiphilic surfaces. We report the straightforward preparation of antifouling thin film coatings in both categories via initiated chemical vapor deposition. A molecular force spectroscopy-based method is demonstrated as a rapid and quantitative assessment tool for comparing the differences in antifouling characteristics. The fouling propensity of single molecules, as opposed to bulk protein solution or bacterial culture, is assessed. This method allows for the interrogation of molecular interaction without the complication resulted from protein conformational change or micro-organism group interactions. The molecular interaction follows the same trend as bacterial adhesion results obtained previously, demonstrating that molecular force probe is a valid method for the quantification and mechanistic examination of fouling. In addition, the molecular force spectroscopy-based method is able to distinguish differences in antifouling capability that is not resolvable by traditional static protein adsorption tests. To lend further insight into the intrinsic fouling resistance of zwitterionic and amphiphilic surface chemistries, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, advancing and receding water contact angles, and atomic force microscopy are used to elucidate the film properties that are relevant to their antifouling capabilities.

  8. Synthesis of carbon nanotubes by CVD method using iron and molybdenum-based catalysts supported on ceramic matrices;Sintese de nanotubos de carbono por CVD utilizando catalisadores a base de ferro e molibdenio suportados em matrizes ceramicas

    Energy Technology Data Exchange (ETDEWEB)

    Teixeira, Ana Paula de Carvalho

    2010-07-01

    Molybdenum is known for its synergistic effect in the synthesis of carbon nanotubes (CNs) by chemical vapor deposition (CVD method). When added to typical catalysts like iron, nickel, and cobalt, even in small quantities, it is increases the yield of these nanostructures. The presence of Mo also has an influence on the type and number of CN walls formed. Although this effect is widely documented in the literature, there is not yet a consensus about the mechanism of action of molybdenum in catalytic systems. The objective of the present work is to study the influence of molybdenum on the catalytic activity of iron nanoparticle-based catalysts supported on magnesium oxide (Fe/MgO system) in the synthesis of carbon nanotubes by the CVD method. The Mo concentration was systematically varied from null to molar ratio values four times greater than the quantity of Fe, and the obtained material (catalysts and carbon nanotubes) were broadly characterized by different techniques. In order to also study the influence of the preparation method on the final composition of the catalytic system phases, the catalytic systems (Fe/MgO e FeMo{sub x}/MgO) were synthesized by two different methods: co-precipitation and impregnation. The greatest CN yields were observed for the catalysts prepared by coprecipitation. The difference was attributed to better dispersion of the Fe and Mo phases in the catalyst ceramic matrix. In the precipitation stage, it was observed the formation of layered double hydroxides whose concentration increased with the Mo content up to the ratio of Mo/Fe equal to 0.2. This phase is related to a better distribution of Fe and Mo in this concentration range. Another important characteristic observed is that the ceramic matrix is not inert. It can react both with Fe and Mo and form the iron solid solution in the magnesium oxide and the phases magnesium-ferrite (MgFe{sub 2}0{sub 4}) and magnesium molybdate (MgMo0{sub 4}). The MgFe{sub 2}0{sub 4} phase is observed in

  9. Carbon nanostructures from Fe-C nanocomposites by activated CVD methods

    Energy Technology Data Exchange (ETDEWEB)

    Fleaca, Claudiu; Morjan, Ion; Alexandrescu, Rodica; Dumitrache, Florian; Soare, Iuliana; Gavrila-Florescu, Lavinia [Laser Photochemistry Laboratory, NILPRP, Bucharest (Romania); Le Normand, Francois; Faerber, Jaques [Groupe Surfaces and Interfaces, IPCMS, UMR 7504 CNRS, Strasbourg (France)

    2010-04-15

    Iron-based core-shell nanoparticles can present interesting catalytic properties for the growth of carbon nanostructures. We report the synthesis of various carbon nanostructures using activated chemical vapour deposition methods. These structures were analysed by Scanning Electron Microscopy (SEM) and Raman spectroscopy. Laser pyrolysis technique was used for synthesis of less than 10 nm diameter Fe-C core-shell catalyst nanoparticles. Acetone suspensions of Fe-C nanoparticles were drop-casted or spin coated onto Si(100) substrates. The consequence of hydrogen selective etching of these nanocomposites at 550 C, followed by a treatment with a mixture of H{sub 2} and C{sub 2}H{sub 2} at 700 C (both in the presence of hot filaments) was the growth of corrugated ribbons and decorated or distorted carbon nanotubes/nanofibers. Round agglomerate nanoparticles and long and very thin nanotubes were observed on the substrates edges (protected from direct etching). By adding in similar conditions a glow discharge plasma to hot filaments, the resulted deposits contain oriented nanotubes. Due to the implication of the electric field, the presence of both plasma and hot wires seems to significantly change the specific growth conditions of carbon nanostructures towards those resulted when only incandescent filaments were used (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Deposition of low stress, high transmittance SiC as an x-ray mask membrane using ECR plasma CVD

    CERN Document Server

    Lee, S Y; Lim, S T; Ahn, J H

    1998-01-01

    SiC for x-ray mask membrane is deposited by Electron Cyclotron Resonance plasma Chemical Vapor Deposition from SiH sub 4 /CH sub 4 Ar mixtures. Stoichiometric SiC is deposited at SiH sub 4 /CH sub 4 ratio of 0.4, deposition temperature of 600.deg.C and microwave power of 500 W with +- 5% thickness uniformity, As-deposited film has compressive residual stress, very smooth surface (31 A rms) and high optical transmittance of 90% at 633 nm wavelength. The microstructure of this film consists of the nanocrystalline particle (100 A approx 200A) embedded in amorphous matrix. Residual stress can be turned to tensile stress via Rapid Thermal Annealing in N sub 2 atmosphere, while suppressing structural change during annealing, As a result, smooth (37 A rms) SiC film with moderate tensile stress and high optical transmittance (85% at 633 nm wavelength) is obtained.

  11. Novel Diamond Films Synthesis Strategy: Methanol and Argon Atmosphere by Microwave Plasma CVD Method Without Hydrogen

    Science.gov (United States)

    Yang, Li; Jiang, Caiyi; Guo, Shenghui; Zhang, Libo; Gao, Jiyun; Peng, Jinhui; Hu, Tu; Wang, Liang

    2016-09-01

    Diamond thin films are grown on silicon substrates by only using methanol and argon mixtures in microwave plasma chemical vapor deposition (MPCVD) reactor. It is worth mentioning that the novel strategy makes the synthesis reaction works smoothly without hydrogen atmosphere, and the substrates temperature is only 500 °C. The evidence of surface morphology and thickness under different time is obtained by characterizing the samples using scanning electron microscopy (SEM). X-ray diffractometer (XRD) spectrum reveals that the preferential orientation of (111) plane sample is obtained. The Raman spectra indicate that the dominant component of all the samples is a diamond. Moreover, the diamond phase content of the targeted films was quantitatively analyzed by X-ray photoelectron spectroscopy (XPS) method, and the surface roughness of diamond films was investigated by atomic force microscope (AFM). Meanwhile, the possible synthesis mechanism of the diamond films in methanol- and argon-mixed atmosphere was discussed.

  12. The deposit size frequency method for estimating undiscovered uranium deposits

    Science.gov (United States)

    McCammon, R.B.; Finch, W.I.

    1993-01-01

    The deposit size frequency (DSF) method has been developed as a generalization of the method that was used in the National Uranium Resource Evaluation (NURE) program to estimate the uranium endowment of the United States. The DSF method overcomes difficulties encountered during the NURE program when geologists were asked to provide subjective estimates of (1) the endowed fraction of an area judged favorable (factor F) for the occurrence of undiscovered uranium deposits and (2) the tons of endowed rock per unit area (factor T) within the endowed fraction of the favorable area. Because the magnitudes of factors F and T were unfamiliar to nearly all of the geologists, most geologists responded by estimating the number of undiscovered deposits likely to occur within the favorable area and the average size of these deposits. The DSF method combines factors F and T into a single factor (F??T) that represents the tons of endowed rock per unit area of the undiscovered deposits within the favorable area. Factor F??T, provided by the geologist, is the estimated number of undiscovered deposits per unit area in each of a number of specified deposit-size classes. The number of deposit-size classes and the size interval of each class are based on the data collected from the deposits in known (control) areas. The DSF method affords greater latitude in making subjective estimates than the NURE method and emphasizes more of the everyday experience of exploration geologists. Using the DSF method, new assessments have been made for the "young, organic-rich" surficial uranium deposits in Washington and idaho and for the solution-collapse breccia pipe uranium deposits in the Grand Canyon region in Arizona and adjacent Utah. ?? 1993 Oxford University Press.

  13. Epitaxial Growth of beta-Silicon Carbide (SiC) on a Compliant Substrate via Chemical Vapor Deposition (CVD)

    Science.gov (United States)

    Mitchell, Sharanda L.

    1996-01-01

    Many lattice defects have been attributed to the lattice mismatch and the difference in the thermal coefficient of expansion between SiC and silicon (Si). Stacking faults, twins and antiphase boundaries are some of the lattice defects found in these SiC films. These defects may be a partial cause of the disappointing performance reported for the prototype devices fabricated from beta-SiC films. The objective of this research is to relieve some of the thermal stress due to lattice mismatch when SiC is epitaxially grown on Si. The compliant substrate is a silicon membrane 2-4 microns thick. The CVD process includes the buffer layer which is grown at 1360 C followed by a very thin epitaxial growth of SiC. Then the temperature is raised to 1500 C for the subsequent growth of SiC. Since silicon melts at 1415 C, the SiC will be grown on molten Silicon which is absorbed by a porous graphite susceptor eliminating the SiC/Si interface. We suspect that this buffer layer will yield less stressed material to help in the epitaxial growth of SiC.

  14. Tungsten chemical vapor deposition method

    Energy Technology Data Exchange (ETDEWEB)

    Hirano, Kiichi; Takeda, Nobuo.

    1993-07-13

    A tungsten chemical vapor deposition method is described, comprising: a first step of selectively growing a first thin tungsten film of a predetermined thickness in a desired region on the surface of a silicon substrate by reduction of a WF[sub 6] gas introduced into an atmosphere of a predetermined temperature containing said silicon substrate; and a second step of selectively growing a second tungsten film of a predetermined thickness on said first thin tungsten film by reduction of said WF[sub 6] with a silane gas further introduced into said atmosphere, wherein the surface state of said substrate is monitored by a pyrometer and the switching from said first step to said second step is performed when the emissivity of infrared light from the substrate surfaces reaches a predetermined value.

  15. A comparison of different spray chemical vapour deposition methods for the production of undoped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Garnier, Jerome [Arts et Metiers Paris Tech LPMI2, bd du Ronceray, BP 3525, 49035 ANGERS Cedex (France); Bouteville, Anne, E-mail: Anne.Bouteville@angers.ensam.f [Arts et Metiers Paris Tech LPMI2, bd du Ronceray, BP 3525, 49035 ANGERS Cedex (France); Hamilton, Jeff; Pemble, Martyn E.; Povey, Ian M. [Tyndall National Institute, University College Cork, Lee Maltings, Prospect Row, Cork (Ireland)

    2009-12-15

    Two different methods of spray chemical vapour deposition have been used to grow ZnO thin films on glass substrates from zinc acetate solution over the temperature range 400 {sup o}C to 550 {sup o}C. The first of these is named InfraRed Assisted Spray Chemical Vapour Deposition (IRAS-CVD). This method uses intense IR radiation to heat not only the substrate but also the gaseous species entering the reactor. The second method is a more conventional approach known simply as ultrasonic spray CVD, which utilises IR lamps to heat the substrate only. By way of comparing these two approaches we present data obtained from contact angle measurements, crystallinity and mean crystallite size, photoluminescence, electrical and optical properties. Additionally we have examined the role of annealing within the IRAS-CVD reactor environment.

  16. On the development of single and multijunction solar cells with hot-wire CVD deposited active layers

    NARCIS (Netherlands)

    Li, H. B. T.; Franken, R.H.; Stolk, R.L.; Schuttauf, J.A.; van der Werf, C.H.M.; Rath, J.K.; Schropp, R.E.I.

    2008-01-01

    We present an overview of the scientific challenges and achievements during the development of thin film silicon based single and multijunction solar cells with hot-wire chemical vapor deposition (HWCVD) of the active silicon layers. The highlights discussed include the development of Ag/ZnO coating

  17. Microcrystalline silicon from very high frequency plasma deposition and hot-wire CVD for ``micromorph`` tandem solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Brummack, H.; Brueggemann, R.; Wanka, H.N.; Hierzenberger, A.; Schubert, M.B. [Univ. Stuttgart (Germany). Inst. fuer Physikalische Elektronik

    1997-12-31

    The authors have grown microcrystalline silicon from a glow discharge at very high frequencies of 55 MHz and 170 MHz with high hydrogen dilution, and also, at more than 10 times higher growth rates, similar films by hot-wire chemical vapor deposition. Both kinds of materials have extensively been characterized and compared in terms of structural, optical and electronic properties, which greatly improve by deposition in a multi- instead of a single-chamber system. Incorporation of these different materials into pin solar cells results in open circuit voltages of about 400 mV as long as the doped layers are microcrystalline and rise to more than 870 mV if amorphous p- and n-layers are used. Quantum efficiencies and fill factors are still poor but leave room for further improvement, as clearly demonstrated by a remarkable reverse bias quantum efficiency gain.

  18. The features of CNT growth on catalyst-content amorphous alloy layer by CVD-method

    Science.gov (United States)

    Dubkov, S.; Bulyarskii, S.; Pavlov, A.; Trifonov, A.; Kitsyuk, E.; Mierczynski, P.; Maniecki, T.; Ciesielski, R.; Gavrilov, S.; Gromov, D.

    2016-12-01

    This work is devoted to the CVD-synthesis of arrays of carbon nanotubes (CNTs) on Co-Zr-N-(O), Ni-Nb-N-(O), Co- Ta-N-(O) catalytic alloy films from gas mixture of C2H2+NH3+Ar at a substrate temperature of about 550°C.Heating of the amorphous alloy causes its crystallization and squeezing of the catalytic metal onto the surface. As a result, small catalyst particles are formed on the surface. The CNT growth takes place after wards on these particles. It should be noted that the growth of CNT arrays on these alloys is insensitive to the thickness of alloy film, which makes this approach technically attractive. In particular, the possibility of local CNT growth at the ends of the Co-Ta-N-(O) film and three-level CNT growth at the end of more complex structure SiO2/Ni-Nb-N-O/SiO2/Ni-Nb-N-O/SiO2/Ni-Nb-N-O/SiO2 is demonstrated.

  19. Fabrication of contamination-free CVD Graphene devices using soak and peel method

    Science.gov (United States)

    Sebastian, Abhilash; Kakatkar, Aniket; de Alba, Roberto; Zhelev, Nikolay; McEuen, Paul; Craighead, Harold; Parpia, Jeevak

    2014-03-01

    Large area graphene-based devices are commonly fabricated by transferring the CVD grown graphene from metal foils to semiconductor substrates. However, during device fabrication, the transfer process involves chemical etching of metal that leads to the degradation of electrical properties of graphene. Recently, a clean transfer of graphene to devices with improved electrical properties, by delamination of graphene from metal substrates by soak and peel using DI-water has been demonstrated. We employed the soak and peel scheme to fabricate graphene transistor arrays on a SiO2/Si substrate with a back gate configuration. The source-drain contacts are patterned using Ti/Pt with graphene channel length varying from 2-50um. The graphene is transferred subsequently to the substrate and yields a high quality junction between metal electrodes and graphene. The contact resistance is low and the Dirac peak is observed across the array. The suitability of the graphene transistors for chemical functionalization will be presented. Possible application of this transfer technique for fabricating large area suspended nano-electro mechanical systems will be discussed.

  20. Atmospheric pressure CVD of SNO2 and ZNO:AL

    NARCIS (Netherlands)

    Deelen, J. van; Kniknie, B.J.; Steijvers, H.L.A.H.; Mannie, G.; Thune, P.; Illiberi, A.

    2012-01-01

    Atmospheric pressure CVD (APCVD) is a highly cost effective method of depositing transparent conductive oxides (TCOs). In this work, insights in alcohol addition in the widely applied SnO2 process are discussed, including high resolution TEM images. Furthermore, the APCVD process of ZnO:Al was demon

  1. Optical spectroscopic analyses of CVD plasmas used in the deposition of transparent and conductive ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Martin, A.; Espinos, J.P.; Yubero, F.; Barranco, A.; Gonzalez-Elipe, A.R. [Instituto de Ciencias de Materiales de Sevilla, CSIC-Universidad de Sevilla (Spain); Cotrino, J. [Universidad de Sevilla, Facultad de Fisica, Dept. de Fisica Atomica, Molecular y Nuclear, Sevilla (Spain)

    2001-07-01

    Transparent conducting ZnO:A1 thin films have been prepared by remote plasma enhanced chemical vapor deposition. Emission line profiles were recorded as a function of different plasma gas composition (oxygen and hydrogen mixtures) and different rates of precursors (Zn(C{sub 2}H{sub 5}){sub 2} and A1(CH{sub 3}){sub 3}) in the downstream zone of the plasma reactor. Optical emission spectroscopy were used to characterize the oxygen/hydrogen plasma as a function of hydrogen flow rate. The variation of plasma hydrogen content has an important influence in the resistivity of the films. (authors)

  2. Thermally Induced Nano-Structural and Optical Changes of nc-Si:H Deposited by Hot-Wire CVD

    Directory of Open Access Journals (Sweden)

    Muller TFG

    2009-01-01

    Full Text Available Abstract We report on the thermally induced changes of the nano-structural and optical properties of hydrogenated nanocrystalline silicon in the temperature range 200–700 °C. The as-deposited sample has a high crystalline volume fraction of 53% with an average crystallite size of ~3.9 nm, where 66% of the total hydrogen is bonded as ≡Si–H monohydrides on the nano-crystallite surface. A growth in the native crystallite size and crystalline volume fraction occurs at annealing temperatures ≥400 °C, where hydrogen is initially removed from the crystallite grain boundaries followed by its removal from the amorphous network. The nucleation of smaller nano-crystallites at higher temperatures accounts for the enhanced porous structure and the increase in the optical band gap and average gap.

  3. Thermally Induced Nano-Structural and Optical Changes of nc-Si:H Deposited by Hot-Wire CVD.

    Science.gov (United States)

    Arendse, C J; Malgas, G F; Muller, T F G; Knoesen, D; Oliphant, C J; Motaung, D E; Halindintwali, S; Mwakikunga, B W

    2009-01-21

    We report on the thermally induced changes of the nano-structural and optical properties of hydrogenated nanocrystalline silicon in the temperature range 200-700 degrees C. The as-deposited sample has a high crystalline volume fraction of 53% with an average crystallite size of ~3.9 nm, where 66% of the total hydrogen is bonded as identical withSi-H monohydrides on the nano-crystallite surface. A growth in the native crystallite size and crystalline volume fraction occurs at annealing temperatures >/=400 degrees C, where hydrogen is initially removed from the crystallite grain boundaries followed by its removal from the amorphous network. The nucleation of smaller nano-crystallites at higher temperatures accounts for the enhanced porous structure and the increase in the optical band gap and average gap.

  4. Characterization of nephelium mutabile blume-like structure of carbon nanotubes prepared from palm oil by CVD method

    Science.gov (United States)

    Maryam, M.; Shamsudin, M. S.; Rusop, M.

    2017-09-01

    A new structure of carbon nanotube was produced from the Single furnace Aerosol-assisted Catalytic CVD (SFAACVD) method using Palm Oil (PO) as the precursor and Ferrocene (Fe) as the catalyst. A nephelium mutabile blume (rambutan)-like structure of CNTs was found from the black substance collected from the Alumina boat substrate placed inside the furnace. Temperature of furnace which was heated at 600 °C - 800 °C plays an important role in determining the formation of structure. The formation rambutan-like structure of CNTs was optimized at 700 °C and the samples collected were characterized by Field Emission Scanning Electron Microscope (FE-SEM) to obtain the surface morphologies. Raman Spectroscopy (RS) and Thermogravimetric Analysis (TGA) were then used to further study the Raman Spectra and purity of samples.

  5. Comparative evaluation of CVD diamond technologies

    Energy Technology Data Exchange (ETDEWEB)

    Anthony, T.R. [General Electric Corporate Research & Development Center, Schenectady, NY (United States)

    1993-01-01

    Chemical vapor deposition (CVD) of diamonds occurs from hydrogen-hydrocarbon gas mixtures in the presence of atomic hydrogen at subatmospheric pressures. Most CVD methods are based on different means of generating and transporting atomic hydrogen in a particular system. Evaluation of these different techniques involves their capital costs, material costs, energy costs, labor costs and the type and quality of diamond that they produce. Currently, there is no universal agreement on which is the best technique and technique selection has been largely driven by the professional background of the user as well as the particular application of interest. This article discusses the criteria for evaluating a process for low-pressure deposition of diamond. Next, a brief history of low-pressure diamond synthesis is reviewed. Several specific processes are addressed, including the hot filament process, hot filament electron-assisted chemical vapor deposition, and plasma generation of atomic hydrogen by glow discharge, microwave discharge, low pressure radio frequency discharge, high pressure DC discharge, high pressure microwave discharge jets, high pressure RF discharge, and high and low pressure flames. Other types of diamond deposition methods are also evaluated. 101 refs., 15 figs.

  6. Carbon nanotube prepared from carbon monoxide by CVD method and its application as electrode materials

    Institute of Scientific and Technical Information of China (English)

    AN Yuliang; YUAN Xia; CHENG Shinan; GEN Xin

    2006-01-01

    Carbon nanotubes with larger inner diameter were synthesized by the chemical vapor deposition of carbon monoxide (CO) on iron catalyst using H2S as promoting agent.It is found that the structure and morphology of carbon nanotubes can be tailored, to some degree, by varying the experimental conditions such as precursor components and process parameters.The results show that the presence of H2S may play key role for growing Y-branched carbon nanotubes.The products were characterized by SEM, TEM, and Raman spectroscopy, respectively.Furthermore, the obtained carbon nanotubes were explored as electrode materials for supercapacitor.

  7. Influence of hydrogen dilution on structural, electrical and optical properties of hydrogenated nanocrystalline silicon (nc-Si:H) thin films prepared by plasma enhanced chemical vapour deposition (PE-CVD)

    Energy Technology Data Exchange (ETDEWEB)

    Funde, A.M.; Bakr, Nabeel Ali; Kamble, D.K. [School of Energy Studies, University of Pune, Pune 411 007 (India); Hawaldar, R.R.; Amalnerkar, D.P. [Center for Materials for Electronics Technology (C-MET), Panchawati, Pune 411 008 (India); Jadkar, S.R. [Department of Physics, University of Pune, Ganeshkhind Road, Pune 411 007 (India)

    2008-10-15

    Hydrogenated nanocrystalline silicon (nc-Si:H) thin films were deposited from pure silane (SiH{sub 4}) and hydrogen (H{sub 2}) gas mixture by conventional plasma enhanced chemical vapour deposition (PE-CVD) method at low temperature (200 C) using high rf power. The structural, optical and electrical properties of these films are carefully and systematically investigated as a function of hydrogen dilution of silane (R). Characterization of these films with low angle X-ray diffraction and Raman spectroscopy revealed that the crystallite size in the films tends to decrease and at same time the volume fraction of crystallites increases with increase in R. The Fourier transform infrared (FTIR) spectroscopic analysis showed at low values of R, the hydrogen is predominantly incorporated in the nc-Si:H films in the mono-hydrogen (Si-H) bonding configuration. However, with increasing R the hydrogen bonding in nc-Si:H films shifts from mono-hydrogen (Si-H) to di-hydrogen (Si-H{sub 2}) and (Si-H{sub 2}){sub n} complexes. The hydrogen content in the nc-Si:H films decreases with increase in R and was found less than 10 at% over the entire studied range of R. On the other hand, the Tauc's optical band gap remains as high as 2 eV or much higher. The quantum size effect may responsible for higher band gap in nc-Si:H films. A correlation between electrical and structural properties has been found. For optimized deposition conditions, nc-Si:H films with crystallite size {proportional_to}7.67 nm having good degree of crystallinity ({proportional_to}84%) and high band gap (2.25 eV) were obtained with a low hydrogen content (6.5 at%). However, for these optimized conditions, the deposition rate was quite small (1.6 Aa/s). (author)

  8. Modeling for CVD of Solid Oxide Electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Starr, T.L.

    2002-09-18

    Because of its low thermal conductivity, high thermal expansion and high oxygen ion conductivity yttria-stabilized zirconia (YSZ) is the material of choice for high temperature electrolyte applications. Current coating fabrication methods have their drawbacks, however. Air plasma spray (APS) is a relatively low-cost process and is suitable for large and relatively complex shapes. it is difficult to produce uniform, relatively thin coatings with this process, however, and the coatings do not exhibit the columnar microstructure that is needed for reliable, long-term performance. The electron-beam physical vapor deposition (EB-PVD) process does produce the desirable microstructure, however, the capital cost of these systems is very high and the line-of-sight nature of the process limits coating uniformity and the ability to coat large and complex shapes. The chemical vapor deposition (CVD) process also produces the desirable columnar microstructure and--under proper conditions--can produce uniform coatings over complex shapes. CVD has been used for many materials but is relatively undeveloped for oxides, in general, and for zirconia, in particular. The overall goal of this project--a joint effort of the University of Louisville and Oak Ridge National Laboratory (ORNL)--is to develop the YSZ CVD process for high temperature electrolyte applications. This report describes the modeling effort at the University of Louisville, which supports the experimental work at ORNL. Early work on CVD of zirconia and yttria used metal chlorides, which react with water vapor to form solid oxide. Because of this rapid gas-phase reaction the water generally is formed in-situ using the reverse water-gas-shift reaction or a microwave plasma. Even with these arrangements gas-phase nucleation and powder formation are problems when using these precursors. Recent efforts on CVD of zirconia and YSZ have focused on use of metal-organic precursors (MOCVD). These are more stable in the gas

  9. Atmospheric pressure plasma-initiated chemical vapor deposition (AP-PiCVD) of poly(diethylallylphosphate) coating: a char-forming protective coating for cellulosic textile.

    Science.gov (United States)

    Hilt, Florian; Boscher, Nicolas D; Duday, David; Desbenoit, Nicolas; Levalois-Grützmacher, Joëlle; Choquet, Patrick

    2014-01-01

    An innovative atmospheric pressure chemical vapor deposition method toward the deposition of polymeric layers has been developed. This latter involves the use of a nanopulsed plasma discharge to initiate the free-radical polymerization of an allyl monomer containing phosphorus (diethylallylphosphate, DEAP) at atmospheric pressure. The polymeric structure of the film is evidence by mass spectrometry. The method, highly suitable for the treatment of natural biopolymer substrate, has been carried out on cotton textile to perform the deposition of an efficient and conformal protective coating.

  10. A multifactorial analysis of obesity as CVD risk factor: Use of neural network based methods in a nutrigenetics context

    Directory of Open Access Journals (Sweden)

    Valavanis Ioannis K

    2010-09-01

    Full Text Available Abstract Background Obesity is a multifactorial trait, which comprises an independent risk factor for cardiovascular disease (CVD. The aim of the current work is to study the complex etiology beneath obesity and identify genetic variations and/or factors related to nutrition that contribute to its variability. To this end, a set of more than 2300 white subjects who participated in a nutrigenetics study was used. For each subject a total of 63 factors describing genetic variants related to CVD (24 in total, gender, and nutrition (38 in total, e.g. average daily intake in calories and cholesterol, were measured. Each subject was categorized according to body mass index (BMI as normal (BMI ≤ 25 or overweight (BMI > 25. Two artificial neural network (ANN based methods were designed and used towards the analysis of the available data. These corresponded to i a multi-layer feed-forward ANN combined with a parameter decreasing method (PDM-ANN, and ii a multi-layer feed-forward ANN trained by a hybrid method (GA-ANN which combines genetic algorithms and the popular back-propagation training algorithm. Results PDM-ANN and GA-ANN were comparatively assessed in terms of their ability to identify the most important factors among the initial 63 variables describing genetic variations, nutrition and gender, able to classify a subject into one of the BMI related classes: normal and overweight. The methods were designed and evaluated using appropriate training and testing sets provided by 3-fold Cross Validation (3-CV resampling. Classification accuracy, sensitivity, specificity and area under receiver operating characteristics curve were utilized to evaluate the resulted predictive ANN models. The most parsimonious set of factors was obtained by the GA-ANN method and included gender, six genetic variations and 18 nutrition-related variables. The corresponding predictive model was characterized by a mean accuracy equal of 61.46% in the 3-CV testing sets

  11. Designing polymer surfaces via vapor deposition

    Directory of Open Access Journals (Sweden)

    Ayse Asatekin

    2010-05-01

    Full Text Available Chemical Vapor Deposition (CVD methods significantly augment the capabilities of traditional surface modification techniques for designing polymeric surfaces. In CVD polymerization, the monomer(s are delivered to the surface through the vapor phase and then undergo simultaneous polymerization and thin film formation. By eliminating the need to dissolve macromolecules, CVD enables insoluble polymers to be coated and prevents solvent damage to the substrate. Since de-wetting and surface tension effects are absent, CVD coatings conform to the geometry of the underlying substrate. Hence, CVD polymers can be readily applied to virtually any substrate: organic, inorganic, rigid, flexible, planar, three-dimensional, dense, or porous. CVD methods integrate readily with other vacuum processes used to fabricate patterned surfaces and devices. CVD film growth proceeds from the substrate up, allowing for interfacial engineering, real-time monitoring, thickness control, and the synthesis of films with graded composition. This article focuses on two CVD polymerization methods that closely translate solution chemistry to vapor deposition; initiated CVD and oxidative CVD. The basic concepts underlying these methods and the resultant advantages over other thin film coating techniques are described, along with selected applications where CVD polymers are an enabling technology.

  12. Hot Wire CVD for thin film triple junction cells and for ultrafast deposition of the SiN passivation layer on polycrystalline Si solar cells

    NARCIS (Netherlands)

    Schropp, R.E.I.; Franken, R.H.; Goldbach, H.D.; Houweling, Z.S.; Li, H. B. T.; Rath, J.K.; Schuttauf, J.A.; Stolk, R.L.; Verlaan, V.; van der Werf, C.H.M.

    2008-01-01

    We present recent progress on hot-wire deposited thin film solar cells and applications of silicon nitride. The cell efficiency reached for μc-Si:H n–i–p solar cells on textured Ag/ZnO presently is 8.5%, in line with the state-of-the-art level for μc-Si:H n–i–p's for any method of deposition. Such c

  13. Influence of process pressure on β-SiC growth by CVD

    Science.gov (United States)

    Andreev, A. A.; Sultanov, A. O.; Gusev, A. S.; Kargin, N. I.; Pavlova, E. P.

    2014-10-01

    3C-SiC films grown on Si (100) substrates by CVD method using silane-propane- hydrogen system were analyzed for crystallinity at various process pressures. The deposition experiments were carried out in a shower-head type cold-wall CVD reactor. The influence of growth conditions on a structural modification of experimental samples was studied by X-ray diffraction (XRD) measurements, Fourier transform infrared spectroscopy (FTIR) and spectroscopic ellipsometry (SE).

  14. Synthesis of carbon nanotubes by catalytic vapor decomposition (CVD) method: Optimization of various parameters for the maximum yield

    Indian Academy of Sciences (India)

    Kanchan M Samant; Santosh K Haram; Sudhir Kapoor

    2007-01-01

    This paper describes an effect of flow rate, carrier gas (H2, N2 and Ar) composition, and amount of benzene on the quality and the yield of carbon nanotubes (CNTs) formed by catalytical vapour decomposition (CVD) method. The flow and mass control of gases and precursor vapors respectively were found to be interdependent and therefore crucial in deciding the quality and yield of CNTs. We have achieved this by modified soap bubble flowmeter, which controlled the flow rates of two gases, simultaneously. With the help of this set-up, CNTs could be prepared in any common laboratory. Raman spectroscopy indicated the possibilities of formation of single-walled carbon nanotubes (SWNTs). From scanning electron microscopy (SEM) measurements, an average diameter of the tube/bundle was estimated to be about 70 nm. The elemental analysis using energy dispersion spectrum (EDS) suggested 96 at.wt.% carbon along with ca. 4 at.wt. % iron in the as-prepared sample. Maximum yield and best quality CNTs were obtained using H2 as the carrier gas.

  15. Mo-C Multilayered CVD Coatings

    Directory of Open Access Journals (Sweden)

    A. Sagalovych

    2013-12-01

    Full Text Available Production processes of multi-layered Mo-C coatings by the method of chemical vapor deposition (CVD with the use of organometallic compounds were developed. Coatings are applied on technical purpose steel DIN 1.2379 (H12F1 and DIN 1.7709 (25H2MF (ÉI10 heat-treated ball with the high class of surface roughness (> 10. The average deposition rate was 50 μm / h. The optimal conditions of deposition coatings for different technological schemas were defined. Metallographic investigations of the obtained coatings were carried out. Tribological studies of the friction and wear characteristics of sliding friction in conditions of boundary lubrication of Ï-S multilayered CVD coatings shows, that coatings have low friction coefficients (0075-0095 at loads up to 2.0 kN, showed high resistance to wear and are effective in increasing the stability of the pair for precision friction pairs of hydraulical units.

  16. Synthesis of CVD-graphene on rapidly heated copper foils.

    Science.gov (United States)

    Kim, Sang-Min; Kim, Jae-Hyun; Kim, Kwang-Seop; Hwangbo, Yun; Yoon, Jong-Hyuk; Lee, Eun-Kyu; Ryu, Jaechul; Lee, Hak-Joo; Cho, Seungmin; Lee, Seung-Mo

    2014-05-07

    Most chemical vapor deposition (CVD) systems used for graphene growth mainly employ convection and radiation heat transfer between the heating source and the metal catalyst in order to reach the activation temperature of the reaction, which in general leads to a long synthesis time and poor energy efficiency. Here, we report a highly time- and energy-efficient CVD setup, in which the metal catalyst (Cu) is designed to be physically contacted with a heating source to give quick heat transfer by conduction. The induced conduction heating enabled the usual effects of the pretreatment and annealing of Cu (i.e., annihilation of surface defects, impurities and contaminants) to be achieved in a significantly shorter time compared to conventional CVD. Notably, the rapid heating was observed to lead to larger grains of Cu with high uniformity as compared to the Cu annealed by conventional CVD, which are believed to be beneficial for the growth of high quality graphene. Through this CVD setup, bundles of high quality (∼252 Ω per square) and large area (over 16 inch) graphenes were able to be readily synthesized in 40 min in a significantly efficient way. When considering ease of scalability, high energy effectiveness and considerable productivity, our method is expected to be welcomed by industrialists.

  17. FTIR monitoring of industrial scale CVD processes

    Science.gov (United States)

    Hopfe, V.; Mosebach, H.; Meyer, M.; Sheel, D.; Grählert, W.; Throl, O.; Dresler, B.

    1998-06-01

    The goal is to improve chemical vapour deposition (CVD) and infiltration (CVI) process control by a multipurpose, knowledge based feedback system. For monitoring the CVD/CVI process in-situ FTIR spectroscopic data has been identified as input information. In the presentation, three commonly used, and distinctly different, types of industrial CVD/CVI processes are taken as test cases: (i) a thermal high capacity CVI batch process for manufacturing carbon fibre reinforced SiC composites for high temperature applications, (ii) a continuously driven CVD thermal process for coating float glass for energy protection, and (iii) a laser stimulated CVD process for continuously coating bundles of thin ceramic fibers. The feasibility of the concept with FTIR in-situ monitoring as a core technology has been demonstrated. FTIR monitoring sensibly reflects process conditions.

  18. THz-conductivity of CVD graphene on different substrates

    OpenAIRE

    Gabriel Cortés, Daniel; Sempere, Bernat; Colominas, Carles; Ferrer Anglada, Núria

    2015-01-01

    Optoelectronic properties of CVD graphene are charac-terized over a wide frequency range: THz, IR, visible and near-UV. We used Raman spectroscopy to characterize the synthesized graphene films. All graphene layers were deposited on various substrates, some ones transparent or flexible, such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), quartz and silicon. Transmission Terahertz time-domain spectroscopy (THz-TDS) method, in the range from 100 GHz to 3 THz, is used to an...

  19. Synthesis and Characterization of Tin(IV) Oxide Obtained by Chemical Vapor Deposition Method

    Science.gov (United States)

    Nagirnyak, Svitlana V.; Lutz, Victoriya A.; Dontsova, Tatiana A.; Astrelin, Igor M.

    2016-07-01

    The effect of precursors on the characteristics of tin oxide obtained by chemical vapor deposition (CVD) method was investigated. The synthesis of nanosized tin(IV) oxide was carried out with the use of two different precursors: tin(II) oxalate obtained using tin chloride(II) and oxalic acid; tin(II) oxalate obtained using tin chloride(II); and ammonium oxalate. The synthesized tin(IV) oxide samples were studied by electron microscopy, X-ray diffraction and optical spectra. The lattice parameters of tin(IV) oxide samples were defined, the bandgap of samples were calculated.

  20. Synthesis and Characterization of Tin(IV) Oxide Obtained by Chemical Vapor Deposition Method

    OpenAIRE

    Nagirnyak, Svitlana V.; Lutz, Victoriya A.; Dontsova, Tatiana A.; Astrelin, Igor M.

    2016-01-01

    The effect of precursors on the characteristics of tin oxide obtained by chemical vapor deposition (CVD) method was investigated. The synthesis of nanosized tin(IV) oxide was carried out with the use of two different precursors: tin(II) oxalate obtained using tin chloride(II) and oxalic acid; tin(II) oxalate obtained using tin chloride(II); and ammonium oxalate. The synthesized tin(IV) oxide samples were studied by electron microscopy, X-ray diffraction and optical spectra. The lattice parame...

  1. CVD diamond - fundamental phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Yarbrough, W.A. [Pennsylvania State Univ., University Park (United States)

    1993-01-01

    This compilation of figures and diagrams addresses the basic physical processes involved in the chemical vapor deposition of diamond. Different methods of deposition are illustrated. For each method, observations are made of the prominent advantages and disadvantages of the technique. Chemical mechanisms of nucleation are introduced.

  2. 电蚀抛光CVD金刚石膜的实验研究%A Study on the Polishing of CVD Diamond Film by Electromachining Method

    Institute of Scientific and Technical Information of China (English)

    郭钟宁; 王成勇; 匡同春; 王晓初; 黄志刚

    2000-01-01

    本文提出了一种新的CVD金刚石膜抛光技术。采用该项技术,可以高效率的完成CVD金刚石膜的粗抛光。CVD金刚石膜表面被预先涂覆一层导电金属,然后采用电蚀方法对该表面进行加工,使金刚石膜突起的尖峰被迅速去除。加工中金刚石表面的石墨化使电蚀加工得以不断延续。通过单脉冲放电试验已经发现涂覆层的材料对金刚石膜的加工效果有很大影响。与普通金属加工相比,金刚石膜的电蚀过程有其完全不同的特征。通过试验和分析,本文还对金刚石膜的电蚀去除机理进行了初步探讨。%A new technique for polishing CVD diamond film has been investigated, by which rough polishing of CVD diamond film can be efficiently carried out. Diamond film is coated with a thin layer of conductive material in advance, and then EDM method is used to machine the coated surface. As a result, peaks on the surface of diamond film axe removed rapidly. During the machining, graphitization of the surface of CVD diamonds film enables EDM process to continue. The discharge experiment of single pulse shows that the material of the coated layer will evidently affect the removal volume of CVD diamond film. Compared with the machining of ordinary metal, the process of ED machining of CVD diamond film has quite different characteristics. By means of the experimental observation and the analysis of the experimental results, the removal mechanism of CVD diamond film has been discussed.

  3. Filtered cathodic arc deposition apparatus and method

    Science.gov (United States)

    Krauss, Alan R.

    1999-01-01

    A filtered cathodic arc deposition method and apparatus for the production of highly dense, wear resistant coatings which are free from macro particles. The filtered cathodic arc deposition apparatus includes a cross shaped vacuum chamber which houses a cathode target having an evaporable surface comprised of the coating material, means for generating a stream of plasma, means for generating a transverse magnetic field, and a macro particle deflector. The transverse magnetic field bends the generated stream of plasma in the direction of a substrate. Macro particles are effectively filtered from the stream of plasma by traveling, unaffected by the transverse magnetic field, along the initial path of the plasma stream to a macro particle deflector. The macro particle deflector has a preformed surface which deflects macro particles away from the substrate.

  4. Hydrogen termination of CVD diamond films by high-temperature annealing at atmospheric pressure

    NARCIS (Netherlands)

    Seshan, V.; Ullien, D.; Castellanos-Gomez, A.; Sachdeva, S.; Murthy, D.H.K.; Savenije, T.J.; Ahmad, H.A.; Nunney, T.S.; Janssens, S.D.; Haenen, K.; Nesládek, M.; Van der Zant, H.S.J.; Sudhölter, E.J.R.; De Smet, L.C.P.M.

    2013-01-01

    A high-temperature procedure to hydrogenate diamond films using molecular hydrogen at atmospheric pressure was explored. Undoped and doped chemical vapour deposited (CVD) polycrystalline diamond films were treated according to our annealing method using a H2 gas flow down to ∼50 ml/min (STP) at ∼850

  5. Comparison of tungsten films grown by CVD and hot-wire assisted atomic layer deposition in a cold-wall reactor

    NARCIS (Netherlands)

    Yang, Mengdi; Aarnink, Antonius A.I.; Kovalgin, Alexeij Y.; Gravesteijn, Dirk J; Wolters, Robertus A.M.; Schmitz, Jurriaan

    In this work, the authors developed hot-wire assisted atomic layer deposition (HWALD) to deposit tungsten (W) with a tungsten filament heated up to 1700–2000 C. Atomic hydrogen (at-H) was generated by dissociation of molecular hydrogen (H2), which reacted with WF6 at the substrate to deposit W. The

  6. iCVD Cyclic Polysiloxane and Polysilazane as Nanoscale Thin-Film Electrolyte: Synthesis and Properties.

    Science.gov (United States)

    Chen, Nan; Reeja-Jayan, B; Liu, Andong; Lau, Jonathan; Dunn, Bruce; Gleason, Karen K

    2016-03-01

    A group of crosslinked cyclic siloxane (Si-O) and silazane (Si-N) polymers are synthesized via solvent-free initiated chemical vapor deposition (iCVD). Notably, this is the first report of cyclic polysilazanes synthesized via the gas-phase iCVD method. The deposited nanoscale thin films are thermally stable and chemically inert. By iCVD, they can uniformly and conformally cover nonplanar surfaces having complex geometry. Although polysiloxanes are traditionally utilized as dielectric materials and insulators, our research shows these cyclic organosilicon polymers can conduct lithium ions (Li(+) ) at room temperature. The conformal coating and the room temperature ionic conductivity make these cyclic organosilicon polymers attractive for use as thin-film electrolytes in solid-state batteries. Also, their synthesis process and properties have been systemically studied and discussed.

  7. Method and apparatus for electrospark deposition

    Energy Technology Data Exchange (ETDEWEB)

    Bailey, Jeffrey A.; Johnson, Roger N.; Park, Walter R.; Munley, John T.

    2004-12-28

    A method and apparatus for controlling electrospark deposition (ESD) comprises using electrical variable waveforms from the ESD process as a feedback parameter. The method comprises measuring a plurality of peak amplitudes from a series of electrical energy pulses delivered to an electrode tip. The maximum peak value from among the plurality of peak amplitudes correlates to the contact force between the electrode tip and a workpiece. The method further comprises comparing the maximum peak value to a set point to determine an offset and optimizing the contact force according to the value of the offset. The apparatus comprises an electrode tip connected to an electrical energy wave generator and an electrical signal sensor, which connects to a high-speed data acquisition card. An actuator provides relative motion between the electrode tip and a workpiece by receiving a feedback drive signal from a processor that is operably connected to the actuator and the high-speed data acquisition card.

  8. FY1995 development of a clean CVD process by evaluation and control of gas phase nucleation phenomena; 1995 nendo kisokaku seisei gensho no hyoka to seigyo ni yoru clean CVD process no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    The purpose of this study is to develop a high-rate and clean chemical vapor deposition (CVD) process as a breakthrough technique to overcome the problems that particles generated in the gas phase during CVD process for preparation of functional thin films cause reduced product yield and deterioration of the films. In the CVD process proposed here, reactant gas and generated particles are electrically charged to control the motion of them with an electric field. In this study, gas-phase nucleation phenomena are evaluated both theoretically and experimentally. A high-rate, ionized CVD method is first developed, in which reactant gas and generated particles are charged with negative ions generated from a radioisotope source and the UV/photoelectron method, and the motion of the charged gas and particles is controlled with an electric field. Charging and transport processes of fine particles are then investigated experimentally and theoretically to develop a clean CVD method in which generated particles are removed with the electric forces. As a result, quantitative evaluation of the charging and transport process was made possible. We also developed devices for measuring the size distribution and concentration of fine particles in low pressure gas such as those found in plasma CVD processes. In addition, numerical simulation and experiments in this study for a TEOS/O{sub 3} CVD process to prepare thin films could determine reaction rates which have not been known so far and give information on selecting good operation conditions for the process. (NEDO)

  9. Growth and Photovoltaic Properties of High-Quality GaAs Nanowires Prepared by the Two-Source CVD Method.

    Science.gov (United States)

    Wang, Ying; Yang, Zaixing; Wu, Xiaofeng; Han, Ning; Liu, Hanyu; Wang, Shuobo; Li, Jun; Tse, WaiMan; Yip, SenPo; Chen, Yunfa; Ho, Johnny C

    2016-12-01

    Growing high-quality and low-cost GaAs nanowires (NWs) as well as fabricating high-performance NW solar cells by facile means is an important development towards the cost-effective next-generation photovoltaics. In this work, highly crystalline, dense, and long GaAs NWs are successfully synthesized using a two-source method on non-crystalline SiO2 substrates by a simple solid-source chemical vapor deposition method. The high V/III ratio and precursor concentration enabled by this two-source configuration can significantly benefit the NW growth and suppress the crystal defect formation as compared with the conventional one-source system. Since less NW crystal defects would contribute fewer electrons being trapped by the surface oxides, the p-type conductivity is then greatly enhanced as revealed by the electrical characterization of fabricated NW devices. Furthermore, the individual single NW and high-density NW parallel arrays achieved by contact printing can be effectively fabricated into Schottky barrier solar cells simply by employing asymmetric Ni-Al contacts, along with an open circuit voltage of ~0.3 V. All these results indicate the technological promise of these high-quality two-source grown GaAs NWs, especially for the realization of facile Schottky solar cells utilizing the asymmetric Ni-Al contact.

  10. Growth and Photovoltaic Properties of High-Quality GaAs Nanowires Prepared by the Two-Source CVD Method

    Science.gov (United States)

    Wang, Ying; Yang, Zaixing; Wu, Xiaofeng; Han, Ning; Liu, Hanyu; Wang, Shuobo; Li, Jun; Tse, WaiMan; Yip, SenPo; Chen, Yunfa; Ho, Johnny C.

    2016-04-01

    Growing high-quality and low-cost GaAs nanowires (NWs) as well as fabricating high-performance NW solar cells by facile means is an important development towards the cost-effective next-generation photovoltaics. In this work, highly crystalline, dense, and long GaAs NWs are successfully synthesized using a two-source method on non-crystalline SiO2 substrates by a simple solid-source chemical vapor deposition method. The high V/III ratio and precursor concentration enabled by this two-source configuration can significantly benefit the NW growth and suppress the crystal defect formation as compared with the conventional one-source system. Since less NW crystal defects would contribute fewer electrons being trapped by the surface oxides, the p-type conductivity is then greatly enhanced as revealed by the electrical characterization of fabricated NW devices. Furthermore, the individual single NW and high-density NW parallel arrays achieved by contact printing can be effectively fabricated into Schottky barrier solar cells simply by employing asymmetric Ni-Al contacts, along with an open circuit voltage of ~0.3 V. All these results indicate the technological promise of these high-quality two-source grown GaAs NWs, especially for the realization of facile Schottky solar cells utilizing the asymmetric Ni-Al contact.

  11. Development of CVD diamond detectors for clinical dosimetry

    Science.gov (United States)

    Piliero, M. A.; Hugtenburg, R. P.; Ryde, S. J. S.; Oliver, K.

    2014-11-01

    The use of chemical vapour deposition (CVD) methods for the manufacture of diamonds could lead to detectors for high-resolution radiotherapy dosimetry that are cheaper and more reproducible than detectors based on natural diamonds. In this work two prototype designs (Diamond Detectors Ltd, Poole) of CVD diamond detectors were considered. The detectors were encapsulated in a water-proof housing in a form-factor that would be suitable for dosimetry measurements in water, as well as solid material phantoms. Stability of the dosimeter over time, the dose-response, dose-rate response and angular-response were examined. The study demonstrated that the detector behaviour conformed with theory in terms of the dose-rate response and had acceptable properties for use in the clinic.

  12. Heat transfer model of an iCVD reactor

    NARCIS (Netherlands)

    Bakker, R.; Verlaan, V.; Verkerk, A.D.; van der Werf, C.H.M.; van Dijk, L.; Rudolph, H.; Rath, J.K.; Schropp, R.E.I.

    2009-01-01

    Contrary to conventional HWCVD, the power consumption in the iCVD process is dominated by heat conduction rather than radiation. This is due to the fact that while the typical wire temperature for HWCVD is about 1750–2200 °C, for iCVD the temperature is only 250–500 °C. Typical deposition pressures

  13. Deposition of silicon nitride thin films by hot-wire CVD at 100 {sup o}C and 250 {sup o}C

    Energy Technology Data Exchange (ETDEWEB)

    Alpuim, P., E-mail: palpuim@fisica.uminho.p [Departamento de Fisica, Universidade do Minho, 4800-058 Guimaraes (Portugal); Goncalves, L.M. [Departamento de Electronica Industrial, Universidade do Minho, 4800-058 Guimaraes (Portugal); Marins, E.S. [Departamento de Fisica, Universidade do Minho, 4800-058 Guimaraes (Portugal); Viseu, T.M.R. [Departamento de Fisica, Universidade do Minho, 4710-057 Braga (Portugal); Ferdov, S. [Departamento de Fisica, Universidade do Minho, 4800-058 Guimaraes (Portugal); Bouree, J.E. [Laboratoire de Physique des Interfaces et des Couches Minces, CNRS UMR 7647, Ecole Polytechnique, 91128 Palaiseau (France)

    2009-04-30

    Silicon nitride thin films for use as passivation layers in solar cells and organic electronics or as gate dielectrics in thin-film transistors were deposited by the Hot-wire chemical vapor deposition technique at a high deposition rate (1-3 A/s) and at low substrate temperature. Films were deposited using NH{sub 3}/SiH{sub 4} flow rate ratios between 1 and 70 and substrate temperatures of 100 {sup o}C and 250 {sup o}C. For NH{sub 3}/SiH{sub 4} ratios between 40 and 70, highly transparent (T {approx} 90%), dense films (2.56-2.74 g/cm{sup 3}) with good dielectric properties and refractive index between 1.93 and 2.08 were deposited on glass substrates. Etch rates in BHF of 2.7 A/s and < 0.5 A/s were obtained for films deposited at 100 {sup o}C and 250 {sup o}C, respectively. Films deposited at both substrate temperatures showed electrical conductivity {approx} 10{sup -14} {Omega}{sup -1} cm{sup -1} and breakdown fields > 10 MV cm{sup -1}.

  14. Fabrication of Titanium Dioxide Thin Films by DBD-CVD Under Atmosphere

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xi-wen; GUO Yu; HAN Gao-rong

    2007-01-01

    Titanium dioxide films were firstly deposited on glass substrate by DBD-CVD (dielectric barrier discharge enhanced chemical vapor deposition) technique.The structure of the films was investigated by X-ray diffraction (XRD),scanning electron microscopy (SEM).TiO2 films deposited under atmosphere pressure show preferred orientation,and exhibit columnar-like structure,while TiO2 films deposited under low gas pressure show no preferred orientation.The columnar-like structure with preferred orientation exhibits higher photocatalytic efficiency,since the columnar structure has larger surface area.However,it contributes little to the improvement of hydrophilicity. DBD-CVD is an alternative method to prepare photocatalytic TiO2 for its well-controllable property.

  15. Photochemical CVD of Ru on functionalized self-assembled monolayers from organometallic precursors

    Science.gov (United States)

    Johnson, Kelsea R.; Arevalo Rodriguez, Paul; Brewer, Christopher R.; Brannaka, Joseph A.; Shi, Zhiwei; Yang, Jing; Salazar, Bryan; McElwee-White, Lisa; Walker, Amy V.

    2017-02-01

    Chemical vapor deposition (CVD) is an attractive technique for the metallization of organic thin films because it is selective and the thickness of the deposited film can easily be controlled. However, thermal CVD processes often require high temperatures which are generally incompatible with organic films. In this paper, we perform proof-of-concept studies of photochemical CVD to metallize organic thin films. In this method, a precursor undergoes photolytic decomposition to generate thermally labile intermediates prior to adsorption on the sample. Three readily available Ru precursors, CpRu(CO)2Me, (η3-allyl)Ru(CO)3Br, and (COT)Ru(CO)3, were employed to investigate the role of precursor quantum yield, ligand chemistry, and the Ru oxidation state on the deposition. To investigate the role of the substrate chemistry on deposition, carboxylic acid-, hydroxyl-, and methyl-terminated self-assembled monolayers were used. The data indicate that moderate quantum yields for ligand loss (φ ≥ 0.4) are required for ruthenium deposition, and the deposition is wavelength dependent. Second, anionic polyhapto ligands such as cyclopentadienyl and allyl are more difficult to remove than carbonyls, halides, and alkyls. Third, in contrast to the atomic layer deposition, acid-base reactions between the precursor and the substrate are more effective for deposition than nucleophilic reactions. Finally, the data suggest that selective deposition can be achieved on organic thin films by judicious choice of precursor and functional groups present on the substrate. These studies thus provide guidelines for the rational design of new precursors specifically for selective photochemical CVD on organic substrates.

  16. Chromized Layers Produced on Steel Surface by Means of CVD

    Institute of Scientific and Technical Information of China (English)

    KASPRZYCKA Ewa; BOGDA(N)SKI Bogdan; JEZIORSKI Leopold; JASI(N)SKI J(o)zef; TORBUS Roman

    2004-01-01

    Chemical vapour deposition of chromium on the surface of carbon steel has been investigated using a novel CVD method that combines the low cost of pack cementation method with advantages of vacuum technique. The processes have been performed in chromium chlorides atmosphere at a low pressure range from 1 to 800 hPa, the treatment temperature 800 to 950℃. Studies of the layers thickness, the phase composition, Cr, C and Fe depth profiles in diffusion zone have been conducted. The effect of the vacuum level during the process and the process parameters such as time and temperature on layer diffusion growth on the carbon steel surface has been investigated.

  17. CVD carbon powders modified by ball milling

    Directory of Open Access Journals (Sweden)

    Kazmierczak Tomasz

    2015-09-01

    Full Text Available Carbon powders produced using a plasma assisted chemical vapor deposition (CVD methods are an interesting subject of research. One of the most interesting methods of synthesizing these powders is using radio frequency plasma. This method, originally used in deposition of carbon films containing different sp2/sp3 ratios, also makes possible to produce carbon structures in the form of powder. Results of research related to the mechanical modification of these powders have been presented. The powders were modified using a planetary ball mill with varying parameters, such as milling speed, time, ball/powder mass ratio and additional liquids. Changes in morphology and particle sizes were measured using scanning electron microscopy and dynamic light scattering. Phase composition was analyzed using Raman spectroscopy. The influence of individual parameters on the modification outcome was estimated using statistical method. The research proved that the size of obtained powders is mostly influenced by the milling speed and the amount of balls. Powders tend to form conglomerates sized up to hundreds of micrometers. Additionally, it is possible to obtain nanopowders with the size around 100 nm. Furthermore, application of additional liquid, i.e. water in the process reduces the graphitization of the powder, which takes place during dry milling.

  18. X-Ray structural and gas phase studies of silver(i) perfluorinated carboxylate complexes with 2,2'-bipyridyl as potential precursors for chemical vapour deposition (CVD).

    Science.gov (United States)

    Szłyk, Edward; Szczesny, Robert; Wojtczak, Andrzej

    2010-02-21

    [Ag(CF(3)COO)(bpy)] (), [Ag(2)(C(2)F(5)COO)(2)(bpy)] () and [Ag(2)(C(3)F(7)COO)(2)(bpy)] () were prepared and characterized by MS-EI, (1)H, (13)C NMR, variable-temperature IR (VT-IR) spectroscopy (solid sample and evolved volatile species) and thermal analysis. Single-crystal X-ray diffraction data revealed the polymeric structure for [Ag(2)(C(2)F(5)COO)(2)(bpy)] and [Ag(6)(C(3)F(7)COO)(6)(bpy)(4)], with bridging bpy ligand, whereas for [Ag(CF(3)COO)(bpy)] the dimeric system with monodentately linked carboxylate was noted. Mass spectra analysis of () over 30-300 degrees C indicates the presence of binuclear ions [(RCOO)Ag(2)](+) as a main volatile particles, which can be transported in CVD process. VT-IR studies of gases evolved during the thermal decomposition process, demonstrate the presence of fluorocarbon species and CO(2) as the most abundant molecules. Thermal analysis of () revealed a multi-stage decomposition mechanism resulting in Ag(0) formation below 290 degrees C. Compounds were tested for silver metal spray pyrolysis and obtained layers were characterized by scanning electron microscopy (SEM-EDX) and XRD.

  19. Faraday effect of polycrystalline bismuth iron garnet thin film prepared by mist chemical vapor deposition method

    Science.gov (United States)

    Yao, Situ; Kamakura, Ryosuke; Murai, Shunsuke; Fujita, Koji; Tanaka, Katsuhisa

    2017-01-01

    We have synthesized polycrystalline thin film composed of a single phase of metastable bismuth iron garnet, Bi3Fe5O12, on a fused silica substrate, one of the most widely utilized substrates in the solid-state electronics, by using mist chemical vapor deposition (mist CVD) method. The phase purity and stoichiometry are confirmed by X-ray diffraction and Rutherford backscattering spectrometry. The resultant thin film shows a small surface roughness of 3.251 nm. The saturation magnetization at room temperature is 1200 G, and the Faraday rotation angle at 633 nm reaches -5.2 deg/μm. Both the magnetization and the Faraday rotation angles are somewhat higher than those of polycrystalline BIG thin films prepared by other methods.

  20. Method for localized deposition of noble metal catalysts with control of morphology

    Science.gov (United States)

    Ricco, Antonio J.; Manginell, Ronald P.; Huber, Robert J.

    1998-01-01

    A combustible gas sensor that uses a resistively heated, noble metal-coated, micromachined polycrystalline Si filament to calorimetrically detect the presence and concentration of combustible gases. A thin catalytic Pt film was deposited by CVD from the precursor Pt(acac).sub.2 onto microfilaments resistively heated to approximately 500 .degree. C.; Pt deposits only on the hot filament. The filaments tested to date are 2 .mu.m thick .times.10 .mu.m wide .times.100, 250, 500, or 1000 .mu.m-long polycrystalline Si; some are overcoated with a 0.25 .mu.m-thick protective CVD Si.sub.3 N.sub.4 layer.

  1. Correlation between optical emission spectra and the process parameters of a 915 MHz microwave plasma CVD reactor used for depositing polycrystalline diamond coatings

    Indian Academy of Sciences (India)

    Awadesh Kumar Mallik; Sandip Bysakh; Someswar Dutta; Debabrata Basu

    2014-08-01

    In this paper, the hydrogen and hydrogen-methane mixed plasma have been generated inside a 33 cm diameter quartz bell jar with a low power (9 KW) and lower frequency 915 MHz microwave plasma chemical vapor deposition system. The reactor is being used for growing polycrystalline diamond (PCD) over large area (100 mm). The generated plasma is diagnosed by in situ optical emission spectroscopy method with wave length ranging from 200 to 900 nm. The effects of microwave power, chamber pressure and gas concentration on plasma characteristics have been studied in this work. Within the optical range, Balmer H, H, C2swan band and CH lines have been detected at the wavelengths of 655.95, 485.7, 515.82 and 430.17 nm, respectively. It has been observed that for hydrogen plasma, the amount of transition from hydrogen atom inner shell 3 to 2 (H) is almost constant with increasing microwave (MW) power (from 2000 to 2800 W) and pressure (from 15 to 30 Torr) initially, after that it increases with further increase of MW power and pressure, whereas, the transition from 4 to 2 (H) is slowly increased with increasing MW power and pressure. For hydrogen-methane plasma, intensities of C2 swan band, i.e., the transitions from D$^3\\Pi_\\text{g}$ to A$^3\\Pi_{\\mu}$ energy levels, are also increased with the increasing microwave power and reactor pressure. It has been observed that the radicals present in the plasma are affected by variation of different reactor parameters like pressure, MW power, CH4 concentration, etc.

  2. Thermodynamic study of CVD-ZrO{sub 2} phase diagrams

    Energy Technology Data Exchange (ETDEWEB)

    Torres-Huerta, A.M., E-mail: atorresh@ipn.m [Research Center for Applied Science and Advanced Technology, Altamira-IPN, Altamira C.P.89600 Tamaulipas (Mexico); Vargas-Garcia, J.R. [Dept of Metallurgical Eng., ESIQIE-IPN, Mexico 07300 D.F. (Mexico); Dominguez-Crespo, M.A. [Research Center for Applied Science and Advanced Technology, Altamira-IPN, Altamira C.P.89600 Tamaulipas (Mexico); Romero-Serrano, J.A. [Dept of Metallurgical Eng., ESIQIE-IPN, Mexico 07300 D.F. (Mexico)

    2009-08-26

    Chemical vapor deposition (CVD) of zirconium oxide (ZrO{sub 2}) from zirconium acetylacetonate Zr(acac){sub 4} has been thermodynamically investigated using the Gibbs' free energy minimization method and the FACTSAGE program. Thermodynamic data Cp{sup o}, DELTAH{sup o} and S{sup o} for Zr(acac){sub 4} have been estimated using the Meghreblian-Crawford-Parr and Benson methods because they are not available in the literature. The effect of deposition parameters, such as temperature and pressure, on the extension of the region where pure ZrO{sub 2} can be deposited was analyzed. The results are presented as calculated CVD stability diagrams. The phase diagrams showed two zones, one of them corresponds to pure monoclinic phase of ZrO{sub 2} and the other one corresponds to a mix of monoclinic phase of ZrO{sub 2} and graphite carbon.

  3. Metallic Tungsten Nanostructures and Highly Nanostructured Thin Films by Deposition of Tungsten Oxide and Subsequent Reduction in a Single Hot-Wire CVD Process

    NARCIS (Netherlands)

    Harks, P.P.R.M.L.; Houweling, Z.S.; de Jong, M.M.; Kuang, Y; Geus, J.W.; Schropp, R.E.I.

    2012-01-01

    The synthesis of metallic tungsten nanostructures and highly nanostructured thin films is presented. Crystalline tungsten oxide nanostructures are deposited on glassy carbon substrates kept at 700 100 8C by oxidizing resistively heated tungsten filaments in an air flow under subatmospheric pressures

  4. Highly conducting phosphorous doped Nc-Si:H thin films deposited at high deposition rate by hot-wire chemical vapor deposition method.

    Science.gov (United States)

    Waman, V S; Kamble, M M; Ghosh, S S; Mayabadi, Azam; Sathe, V G; Amalnekar, D P; Pathan, H M; Jadkar, S R

    2012-11-01

    In this paper, we report the synthesis of highly conducting phosphorous doped hydrogenated nanocrystalline silicon (nc-Si:H) films at substantially low substrate temperature (200 degrees C) by hot-wire chemical vapor deposition (HW-CVD) method using pure silane (SiH4) and phosphine (PH3) gas mixture without hydrogen dilution. Structural, optical and electrical properties of these films were investigated as a function of PH3 gas-phase ratio. The characterization of these films by low-angle X-ray diffraction, Raman spectroscopy and atomic force microscopy revealed that, the incorporation of phosphorous in nc-Si:H induces an amorphization in the nc-Si:H film structure. Fourier transform infrared spectroscopy analysis indicates that hydrogen predominately incorporated in phosphorous doped n-type nc-Si:H films mainly in di-hydrogen species (Si-H2) and poly-hydrogen (Si-H2)n bonded species signifying that the films become porous, and micro-void rich. We have observed high band gap (1.97-2.37 eV) in the films, though the hydrogen content is low (< 1.4 at.%) over the entire range of PH3 gas-phase ratio studied. Under the optimum deposition conditions, phosphorous doped nc-Si:H films with high dark conductivity (sigma Dark -5.3 S/cm), low charge-carrier activation energy (E(act) - 132 meV) and high band gap (- 2.01 eV), low hydrogen content (- 0.74 at.%) were obtained at high deposition rate (12.9 angstroms/s).

  5. CVD growth and processing of graphene for electronic applications

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Shishir; Rezvani, Ehsan; Nolan, Hugo; Duesberg, Georg S. [School of Chemistry, Trinity College Dublin, Dublin 2 (Ireland); Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Dublin 2 (Ireland); McEvoy, Niall; Kim, Hye-Young; Lee, Kangho; Peltekis, Nikos; Weidlich, Anne; Daly, Ronan [Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Dublin 2 (Ireland)

    2011-11-15

    The remarkable properties of graphene have potential for numerous applications; however, their exploitation depends on its reliable production. The chemical vapour deposition (CVD) growth of graphene on metal surfaces has become one of the most promising strategies for the production of high quality graphene in a scaleable manner. Here, we discuss graphene growth on nickel (Ni) and copper (Cu) directly from both gaseous hydrocarbons and solid carbon precursors. Further, we discuss in detail the transfer of graphene films to insulating substrates, by direct and polymer supported transfer methods. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Ultratough CVD single crystal diamond and three dimensional growth thereof

    Science.gov (United States)

    Hemley, Russell J [Washington, DC; Mao, Ho-kwang [Washington, DC; Yan, Chih-shiue [Washington, DC

    2009-09-29

    The invention relates to a single-crystal diamond grown by microwave plasma chemical vapor deposition that has a toughness of at least about 30 MPa m.sup.1/2. The invention also relates to a method of producing a single-crystal diamond with a toughness of at least about 30 MPa m.sup.1/2. The invention further relates to a process for producing a single crystal CVD diamond in three dimensions on a single crystal diamond substrate.

  7. Deposition and Investigation of Hydrophobic Coatings

    Directory of Open Access Journals (Sweden)

    Safonov Aleksey

    2015-01-01

    Full Text Available The fluoropolymer coatings of different morphologies are deposited by the HWCVD (Hot Wire CVD method. The effect of activator filament temperature on the structure of fluoropolymer coating is shown. The results of studying the hydrophobic fluoropolymer coatings with different structures, deposited by the HWCVD method, are presented.

  8. On the origin of self-organization of SiO2 nanodots deposited by CVD enhanced by atmospheric pressure remote microplasma

    Science.gov (United States)

    Arnoult, G.; Belmonte, T.; Kosior, F.; Dossot, M.; Henrion, G.

    2011-05-01

    The origin of organization of nanostructured silica coatings deposited on stainless steel substrates by remote microplasma at atmospheric pressure is investigated. We show by resorting to thermal camera measurements coupled with modelling that deposition, limited to a few seconds in time, occurs at low temperature (~below 420 K) although the gas temperature may reach 1400 K. Raman analyses of deposited films with thicknesses below 1 µm show the presence of oxidized silicon bonded to the metallic surface. The origin of nanodots is explained as follows. Close to the microplasma nozzle, the concentration of oxidizing species and/or the temperature being high enough, a silica thin film is obtained, leading to ceramic-metallic oxide interface that leads to a Volmer-Weber growth mode and to the synthesis of 3D structures over long treatment times. Far from the nozzle, the reactivity decreasing, thin films get a plasma-polymer like behaviour which leads to a Franck-Van der Merwe growth mode and films with a higher density. Other nanostructures, made of hexagonal cells, are observed but remain unexplained.

  9. On the origin of self-organization of SiO{sub 2} nanodots deposited by CVD enhanced by atmospheric pressure remote microplasma

    Energy Technology Data Exchange (ETDEWEB)

    Arnoult, G; Belmonte, T; Kosior, F; Henrion, G [Institut Jean Lamour, Department of Physics and Chemistry of Solids and Surfaces, UMR 7198 CNRS, Nancy-Universite, Parc de Saurupt, CS 14234, F-54042 Nancy Cedex (France); Dossot, M, E-mail: thierry.belmonte@mines.inpl-nancy.fr [Laboratoire de Chimie Physique et Microbiologie pour l' Environnement, UMR 7564 CNRS - Universite Henri Poincare, Nancy-Universite, 405, rue de Vandoeuvre, F-54600 Villers-les-Nancy (France)

    2011-05-04

    The origin of organization of nanostructured silica coatings deposited on stainless steel substrates by remote microplasma at atmospheric pressure is investigated. We show by resorting to thermal camera measurements coupled with modelling that deposition, limited to a few seconds in time, occurs at low temperature ({approx}below 420 K) although the gas temperature may reach 1400 K. Raman analyses of deposited films with thicknesses below 1 {mu}m show the presence of oxidized silicon bonded to the metallic surface. The origin of nanodots is explained as follows. Close to the microplasma nozzle, the concentration of oxidizing species and/or the temperature being high enough, a silica thin film is obtained, leading to ceramic-metallic oxide interface that leads to a Volmer-Weber growth mode and to the synthesis of 3D structures over long treatment times. Far from the nozzle, the reactivity decreasing, thin films get a plasma-polymer like behaviour which leads to a Franck-Van der Merwe growth mode and films with a higher density. Other nanostructures, made of hexagonal cells, are observed but remain unexplained.

  10. Electrochemically assisted deposition of hydroxyapatite on Ti6Al4V substrates covered by CVD diamond films — Coating characterization and first cell biological results

    Energy Technology Data Exchange (ETDEWEB)

    Strąkowska, Paulina [Gdańsk University of Technology, Mechanical Engineering Faculty (Poland); Gdańsk University of Technology, Faculty of Electronics, Telecommunications, and Informatics (Poland); Beutner, René [Max Bergmann Center, Technische Universität Dresden (Germany); Gnyba, Marcin [Gdańsk University of Technology, Faculty of Electronics, Telecommunications, and Informatics (Poland); Zielinski, Andrzej [Gdańsk University of Technology, Mechanical Engineering Faculty (Poland); Scharnweber, Dieter, E-mail: Dieter.Scharnweber@tu-dresden.de [Max Bergmann Center, Technische Universität Dresden (Germany)

    2016-02-01

    Although titanium and its alloys are widely used as implant material for orthopedic and dental applications they show only limited corrosion stability and osseointegration in different cases. The aim of the presented research was to develop and characterize a novel surface modification system from a thin diamond base layer and a hydroxyapatite (HAp) top coating deposited on the alloy Ti6Al4V widely used for implants in contact with bone. This coating system is expected to improve both the long-term corrosion behavior and the biocompatibility and bioactivity of respective surfaces. The diamond base films were obtained by Microwave Plasma Assisted Chemical Vapor Deposition (MW-PACVD); the HAp coatings were formed in aqueous solutions by electrochemically assisted deposition (ECAD) at varying polarization parameters. Scanning electron microscopy (SEM), Raman microscopy, and electrical conductivity measurements were applied to characterize the generated surface states; the calcium phosphate coatings were additionally chemically analyzed for their composition. The biological properties of the coating system were assessed using hMSC cells analyzing for cell adhesion, proliferation, and osteogenic differentiation. Varying MW-PACVD process conditions resulted in composite coatings containing microcrystalline diamond (MCD/Ti-C), nanocrystalline diamond (NCD), and boron-doped nanocrystalline diamond (B-NCD) with the NCD coatings being dense and homogeneous and the B-NCD coatings showing increased electrical conductivity. The ECAD process resulted in calcium phosphate coatings from stoichiometric and non-stoichiometric HAp. The deposition of HAp on the B-NCD films run at lower cathodic potentials and resulted both in the highest coating mass and the most homogenous appearance. Initial cell biological investigations showed an improved cell adhesion in the order B-NCD > HAp/B-NCD > uncoated substrate. Cell proliferation was improved for both investigated coatings whereas ALP

  11. Mass production of CNTs using CVD multi-quartz tubes

    Energy Technology Data Exchange (ETDEWEB)

    Yousef, Samy; Mohamed, Alaa [Dept. of Production Engineering and Printing Technology, Akhbar Elyom Academy, Giza (Egypt)

    2016-11-15

    Carbon nanotubes (CNTs) have become the backbone of modern industries, including lightweight and heavy-duty industrial applications. Chemical vapor deposition (CVD) is considered as the most common method used to synthesize high yield CNTs. This work aims to develop the traditional CVD for the mass production of more economical CNTs, meeting the growing CNT demands among consumers by increasing the number of three particular reactors. All reactors housing is connected by small channels to provide the heat exchange possibility between the chambers, thereby decreasing synthesis time and reducing heat losses inside the ceramic body of the furnace. The novel design is simple and cheap with a lower reacting time and heat loss compared with the traditional CVD design. Methane, hydrogen, argon, and catalyzed iron nanoparticles were used as a carbon source and catalyst during the synthesis process. In addition, CNTs were produced using only a single quartz tube for comparison. The produced samples were examined using XRD, TEM, SEM, FTIR, and TGA. The results showed that the yield of CNTs increases by 287 % compared with those synthesized with a single quartz tube. Moreover, the total synthesis time of CNTs decreases by 37 % because of decreased heat leakage.

  12. PE-CVD fabrication of germanium nanoclusters for memory applications

    Energy Technology Data Exchange (ETDEWEB)

    Duerkop, T. [Institut fuer Materialien und Bauelemente der Elektronik, Leibniz Universitaet Hannover, Appelstrasse 11a, 30167 Hannover (Germany)], E-mail: duerkop@mbe.uni-hannover.de; Bugiel, E. [Institut fuer Materialien und Bauelemente der Elektronik, Leibniz Universitaet Hannover, Appelstrasse 11a, 30167 Hannover (Germany); Costina, I. [IHP GmbH, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); Ott, A.; Peibst, R.; Hofmann, K.R. [Institut fuer Materialien und Bauelemente der Elektronik, Leibniz Universitaet Hannover, Appelstrasse 11a, 30167 Hannover (Germany)

    2008-02-15

    We have investigated Ge nanoclusters (Ge-NC) embedded in silicon dioxide, whose fundamental properties promise improved characteristics in NC flash memory devices as compared to Si nanoclusters. We present a simple new method, based on plasma-enhanced CVD (PE-CVD) deposition of amorphous Ge (a-Ge) onto SiO{sub 2}, to create gate stacks with embedded Ge-NC at vertically well-controlled positions suitable for use in flash memory devices. This process minimizes the exposure of Ge to environmental influences by depositing a-Ge as well as a SiO{sub 2} cap layer in situ within the same deposition chamber. Subsequent high-temperature anneals compatible with the temperature budget of CMOS processing are used for the actual cluster formation. Variation of annealing temperature and duration of this step as well as the thickness of the initial Ge layer controls the average cluster radius and density, as determined by transmission electron microscopy (TEM). Measurements of electrical properties show the capability of samples with NC to store charge.

  13. Developing the Beijing CVD

    Institute of Scientific and Technical Information of China (English)

    LU JINGXIAN

    2006-01-01

    @@ Slowly but surely, the high-end villa property in Beijing is gaining new momentum. Limited amounts of new properties, rising prices and increasing demand will be the trend in the villa market in 2006, real estate experts predict. Among them, the exclusive Central Villa District(CVD), a top-tier villa area along the Wenyu River in northeast Beijing, has emerged as a hot spot of the market.

  14. Developing Single-Wall Carbon Nanotubes into an Industrial Material through the Super-Growth CVD Method

    Science.gov (United States)

    Futaba, Don

    2013-03-01

    Since the discovery of the carbon nanotube (CNT) 20 years ago, extensive effort has been made to utilize their exceptional intrinsic properties toward industrial applications. However, availability has significantly thwarted these endeavors. In one section of my presentation, I will describe our efforts toward the economical mass-production of single-walled carbon nanotubes (SWCNT) based on the water-assisted chemical vapor deposition technique, from which highly efficient synthesis of vertically aligned SWCNTs grow from substrates (SWCNT forests). Further, I will discuss our work to promote the industrial use of SWCNTs as a member of the Technology Research Association for Single-Walled Carbon Nanotubes (TASC) (A consortium of five companies and AIST founded for the specific purpose of developing SWCNT industrial technology.) Specifically, I will present our progress on developing the technology for the synthetic control of SWCNTs and the development of standardized evaluation techniques for the purpose of understanding the relationship between the SWCNT forest structure, e.g. length, density, crystallinity, etc and the targeted property, e.g. conductivity, mechanical reinforcement, etc. Finally, I will present several examples of applications from composites to CNT-based devices. Technology Research Association for Single Wall Carbon Nanotubes (TASC), Japan

  15. Tip-based chemical vapor deposition with a scanning nano-heater

    NARCIS (Netherlands)

    Gaitas, A.

    2013-01-01

    In this preliminary effort, a moving nano-heater directs a chemical vapor deposition reaction (nano-CVD) demonstrating a tip-based nanofabrication (TBN) method. Localized nano-CVD of copper (Cu) and copper oxide (CuO) on a silicon (Si) and silicon oxide (SiO2) substrate from gasses, namely sublimate

  16. Platinum-ruthenium bimetallic clusters on graphite: a comparison of vapor deposition and electroless deposition methods.

    Science.gov (United States)

    Galhenage, Randima P; Xie, Kangmin; Diao, Weijian; Tengco, John Meynard M; Seuser, Grant S; Monnier, John R; Chen, Donna A

    2015-11-14

    Bimetallic Pt-Ru clusters have been grown on highly ordered pyrolytic graphite (HOPG) surfaces by vapor deposition and by electroless deposition. These studies help to bridge the material gap between well-characterized vapor deposited clusters and electrolessly deposited clusters, which are better suited for industrial catalyst preparation. In the vapor deposition experiments, bimetallic clusters were formed by the sequential deposition of Pt on Ru or Ru on Pt. Seed clusters of the first metal were grown on HOPG surfaces that were sputtered with Ar(+) to introduce defects, which act as nucleation sites for Pt or Ru. On the unmodified HOPG surface, both Pt and Ru clusters preferentially nucleated at the step edges, whereas on the sputtered surface, clusters with relatively uniform sizes and spatial distributions were formed. Low energy ion scattering experiments showed that the surface compositions of the bimetallic clusters are Pt-rich, regardless of the order of deposition, indicating that the interdiffusion of metals within the clusters is facile at room temperature. Bimetallic clusters on sputtered HOPG were prepared by the electroless deposition of Pt on Ru seed clusters from a Pt(+2) solution using dimethylamine borane as the reducing agent at pH 11 and 40 °C. After exposure to the electroless deposition bath, Pt was selectively deposited on Ru, as demonstrated by the detection of Pt on the surface by XPS, and the increase in the average cluster height without an increase in the number of clusters, indicating that Pt atoms are incorporated into the Ru seed clusters. Electroless deposition of Ru on Pt seed clusters was also achieved, but it should be noted that this deposition method is extremely sensitive to the presence of other metal ions in solution that have a higher reduction potential than the metal ion targeted for deposition.

  17. A 3D tomographic EBSD analysis of a CVD diamond thin film

    Directory of Open Access Journals (Sweden)

    Tao Liu, Dierk Raabe and Stefan Zaefferer

    2008-01-01

    Full Text Available We have studied the nucleation and growth processes in a chemical vapor deposition (CVD diamond film using a tomographic electron backscattering diffraction method (3D EBSD. The approach is based on the combination of a focused ion beam (FIB unit for serial sectioning in conjunction with high-resolution EBSD. Individual diamond grains were investigated in 3-dimensions particularly with regard to the role of twinning.

  18. Superhydrophobic aluminium-based surfaces: Wetting and wear properties of different CVD-generated coating types

    Science.gov (United States)

    Thieme, M.; Streller, F.; Simon, F.; Frenzel, R.; White, A. J.

    2013-10-01

    In view of generating superhydrophobic aluminium-based surfaces, this work presents further results for the combination of anodic oxidation as the primary pretreatment method and chemical vapour deposition (CVD) variants for chemical modification producing coatings of 250-1000 nm thickness. In detail, CVD involved the utilisation of i - hexafluoropropylene oxide as precursor within the hot filament CVD process for the deposition of poly(tetrafluoroethylene) coatings at alternative conditions (PTFE-AC) and ii - 1,3,5-trivinyltrimethylcyclotrisiloxane for the deposition of polysiloxane coatings (PSi) by initiated CVD. The substrate material was Al Mg1 subjected to usual or intensified sulphuric acid anodisation pretreatments (SAAu, SAAi, respectively) affording various degrees of surface micro-roughness (SAAu weathering and/or mild wear testing. Superhydrophobicity (SH) was observed with the system SAAi + PTFE-AC similarly to former findings with the standard hot filament CVD PTFE coating variant (SAAi + PTFE-SC). The results indicated that the specific coating morphology made an important contribution to the water-repellency, because even some of the SAAu-based samples tended to reveal SH. Subjecting samples to weathering treatment resulted in a general worsening of the wetting behaviour, primarily limited to the receding contact angles. These tendencies were correlated with the chemical composition of the sample surfaces as analysed by X-ray photoelectron spectroscopy. The wear tests showed, as evaluated by scanning electron microscopy and contact angle measurement, that the PTFE coatings were relatively sensitive to friction. This was connected with a dramatic deterioration of the water-repelling properties. PSi-coated surfaces generally showed rather poor water-repellency, but this coating type was surprisingly resistant towards the applied friction test. From these findings it may be concluded that the combination of hydrophobic fluorine containing structure

  19. Method of depositing a high-emissivity layer

    Science.gov (United States)

    Wickersham, Charles E.; Foster, Ellis L.

    1983-01-01

    A method of depositing a high-emissivity layer on a substrate comprising RF sputter deposition of a carbide-containing target in an atmosphere of a hydrocarbon gas and a noble gas. As the carbide is deposited on the substrate the hydrocarbon gas decomposes to hydrogen and carbon. The carbon deposits on the target and substrate causing a carbide/carbon composition gradient to form on the substrate. At a sufficiently high partial pressure of hydrocarbon gas, a film of high-emissivity pure carbon will eventually form over the substrate.

  20. Silicon carbide and other films and method of deposition

    Science.gov (United States)

    Mehregany, Mehran (Inventor); Zorman, Christian A. (Inventor); Fu, Xiao-An (Inventor); Dunning, Jeremy (Inventor)

    2011-01-01

    A method of depositing a ceramic film, particularly a silicon carbide film, on a substrate is disclosed in which the residual stress, residual stress gradient, and resistivity are controlled. Also disclosed are substrates having a deposited film with these controlled properties and devices, particularly MEMS and NEMS devices, having substrates with films having these properties.

  1. Simple fabrication of air-stable black phosphorus heterostructures with large-area hBN sheets grown by chemical vapor deposition method

    Science.gov (United States)

    Sinha, Sapna; Takabayashi, Yuya; Shinohara, Hisanori; Kitaura, Ryo

    2016-09-01

    We have developed a facile and general method to passivate thin black phosphorus (BP) flakes with large-area high-quality monolayer hexagonal boron nitride (hBN) sheets grown by the chemical vapor deposition (CVD) method. In spite of the one-atom-thick structure, the high-quality CVD-grown monolayer hBN has proven to be useful to prevent the degradation of thin BP flakes exfoliated on substrates. Mechanically exfoliated BP flakes prepared on a Si substrate are covered by the monolayer hBN sheet to preserve (otherwise unstable) atomic layered BP flakes from degradation. The present technique can generally be applied to fabricating BP-based electronic devices with much easiness.

  2. A generic strategy for co-presentation of heparin-binding growth factors based on CVD polymerization.

    Science.gov (United States)

    Deng, Xiaopei; Lahann, Joerg

    2012-09-14

    A multifunctional copolymer with both aldehyde and alkyne groups is synthesized by chemical vapor deposition (CVD) for orthogonal co-immobilization of biomolecules. Surface analytical methods including FTIR and XPS are used to confirm the surface modification. Heparin-binding growth factors [basic fibroblast growth factor (bFGF) in this study] can be immobilized through interaction with heparin, which was covalently attached to the CVD surface through an aldehyde-hydrazide reaction. In parallel, an alkyne-azide reaction is used to orthogonally co-immobilize an adhesion peptide as the second biomolecule.

  3. Scalable ZnO nanotube arrays grown on CVD-graphene films

    Directory of Open Access Journals (Sweden)

    J. B. Park

    2016-10-01

    Full Text Available We report the growth of wafer-scale arrays of individually position-controlled and vertically aligned ZnO nanotube arrays on graphene deposited by chemical vapor deposition (CVD-graphene. Introducing two-dimensional layered materials such as graphene as a growth buffer has recently been suggested for growing nanomaterials on traditionally incompatible substrates. However, their growth has been restricted to small areas or had limited controllability. Here, we study the distinct growth behavior of ZnO on CVD-graphene that makes the selective area growth of individual nanostructures on its surface difficult, and propose a set of methods to overcome this. The resulting nanotube arrays, as examined by scanning electron microscopy and transmission electron microscopy, exhibited uniform morphologies and high structural quality over a large area and could be prepared on a broad variety of substrates, including amorphous, metallic, or flexible substrates.

  4. Pulse-height defect in single-crystal CVD diamond detectors

    Energy Technology Data Exchange (ETDEWEB)

    Beliuskina, O.; Imai, N. [The University of Tokyo, Center for Nuclear Study, Wako, Saitama (Japan); Strekalovsky, A.O.; Aleksandrov, A.A.; Aleksandrova, I.A.; Ilich, S.; Kamanin, D.V.; Knyazheva, G.N.; Kuznetsova, E.A.; Mishinsky, G.V.; Pyatkov, Yu.V.; Strekalovsky, O.V.; Zhuchko, V.E. [JINR, Flerov Laboratory of Nuclear Reactions, Dubna, Moscow Region (Russian Federation); Devaraja, H.M. [Manipal University, Manipal Centre for Natural Sciences, Manipal, Karnataka (India); Heinz, C. [II. Physikalisches Institut, Justus-Liebig-Universitaet Giessen, Giessen (Germany); Heinz, S. [II. Physikalisches Institut, Justus-Liebig-Universitaet Giessen, Giessen (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Hofmann, S.; Kis, M.; Kozhuharov, C.; Maurer, J.; Traeger, M. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Pomorski, M. [CEA, LIST, Diamond Sensor Laboratory, CEA/Saclay, Gif-sur-Yvette (France)

    2017-02-15

    The pulse-height versus deposited energy response of a single-crystal chemical vapor deposition (scCVD) diamond detector was measured for ions of Ti, Cu, Nb, Ag, Xe, Au, and of fission fragments of {sup 252} Cf at different energies. For the fission fragments, data were also measured at different electric field strengths of the detector. Heavy ions have a significant pulse-height defect in CVD diamond material, which increases with increasing energy of the ions. It also depends on the electrical field strength applied at the detector. The measured pulse-height defects were explained in the framework of recombination models. Calibration methods known from silicon detectors were modified and applied. A comparison with data for the pulse-height defect in silicon detectors was performed. (orig.)

  5. Metal oxide growth, spin precession measurements and Raman spectroscopy of CVD graphene

    Science.gov (United States)

    Matsubayashi, Akitomo

    The focus of this dissertation is to explore the possibility of wafer scale graphene-based spintronics. Graphene is a single atomic layer of sp 2 bonded carbon atoms that has attracted much attention as a new type of electronic material due to its high carrier mobilities, superior mechanical properties and extremely high thermal conductivity. In addition, it has become an attractive material for use in spintronic devices owing to its long electron spin relaxation time at room temperature. This arises in part from its low spin-orbit coupling and negligible nuclear hyperfine interaction. In order to realize wafer scale graphene spintronics, utilization of CVD grown graphene is crytical due to its scalability. In this thesis, a unique fabrication method of the metal oxide layers on CVD graphene is presented. This is motivated by theoretical work showing that an ultra thin metal oxide film used as a tunnel barrier improves the spin injection efficiency. Introducing a titanium seed layer prior to the aluminum oxide growth showed improved surface and film uniformity and resulted in a completely oxidized film. Utilizing this unique metal oxide film growth process, lateral spin valve devices using CVD graphene as a channel are successfully fabricated. Hanle spin precession measurements are demonstrated on these CVD graphene spin devices. A non-local Hanle voltage model based upon the diffusive spin transport in a solid is utilized to find the spin diffusion length and spin relaxation time of CVD graphene. The measured spin relaxation times in CVD graphene were compatible with the values found in the literature. However, they are an order of magnitude shorter than the theoretical values expected in graphene. To investigate possible origins of this order of magnitude shorter spin relaxation time in graphene, crystal and electrical modifications in CVD graphene are studied throughout the entire device fabrication process. Raman spectroscopy is utilized to track CVD graphene

  6. Properties of CdTe layers deposited by a novel method -Pulsed Plasma Deposition

    OpenAIRE

    Ancora, C.; Nozar, P.; Mittica, G.; Prescimone, F.; A. Neri; Contaldi, S.; Milita, S.; Albonetti, C.; Corticelli, F.; Brillante, A.; Bilotti, I.; Tedeschi, G.; Taliani, C.

    2011-01-01

    CdTe and CdS are emerging as the most promising materials for thin film photovoltaics in the quest of the achievement of grid parity. The major challenge for the advancement of grid parity is the achievement of high quality at the same time as low fabrication cost. The present paper reports the results of the new deposition technique, Pulsed Plasma Deposition (PPD), for the growth of the CdTe layers on CdS/ZnO/quartz and quartz substrates. The PPD method allows to deposit at low temperature. ...

  7. Preparation of a-Si and a-Si-Alloy Films Using an Ion-Gun Chemical Vapor Deposition Method

    Science.gov (United States)

    Haku, Hisao; Sayama, Katsunobu; Matsuoka, Tsugufumi; Tsuda, Shinya; Nakano, Shoichi; Ohnishi, Michitoshi; Kuwano, Yukinori

    1991-07-01

    As a new amorphous-silicon (a-Si) fabrication technique, an ion-gun chemical vapor deposition (CVD) method, in which ions add energy to surface reactions, has been developed. The ion source employed in this gun is of the hot cathode type with a multicapillary anode which creates a collimated gas flow. A-Si:H and a-Ge:H films, fabricated at the substrate temperature of 130°C, show low dihydride bond density and high photosensitivity (4.0× 105 at Eopt˜1.95 eV and 5.1 at Eopt˜1.03 eV, respectively). In addition, a double ion-gun CVD method, for which the energy of two kinds of ion species can be independently controlled, has been developed for fabricating high-quality a-Si-alloy films. Highly photoconductive a-SiGe:H films with low optical gaps (<1.3 eV) were obtained using this fabrication method.

  8. Analysis of Fiber deposition using Automatic Image Processing Method

    Science.gov (United States)

    Belka, M.; Lizal, F.; Jedelsky, J.; Jicha, M.

    2013-04-01

    Fibers are permanent threat for a human health. They have an ability to penetrate deeper in the human lung, deposit there and cause health hazards, e.glung cancer. An experiment was carried out to gain more data about deposition of fibers. Monodisperse glass fibers were delivered into a realistic model of human airways with an inspiratory flow rate of 30 l/min. Replica included human airways from oral cavity up to seventh generation of branching. Deposited fibers were rinsed from the model and placed on nitrocellulose filters after the delivery. A new novel method was established for deposition data acquisition. The method is based on a principle of image analysis. The images were captured by high definition camera attached to a phase contrast microscope. Results of new method were compared with standard PCM method, which follows methodology NIOSH 7400, and a good match was found. The new method was found applicable for evaluation of fibers and deposition fraction and deposition efficiency were calculated afterwards.

  9. Analysis of Fiber deposition using Automatic Image Processing Method

    Directory of Open Access Journals (Sweden)

    Jicha M.

    2013-04-01

    Full Text Available Fibers are permanent threat for a human health. They have an ability to penetrate deeper in the human lung, deposit there and cause health hazards, e.glung cancer. An experiment was carried out to gain more data about deposition of fibers. Monodisperse glass fibers were delivered into a realistic model of human airways with an inspiratory flow rate of 30 l/min. Replica included human airways from oral cavity up to seventh generation of branching. Deposited fibers were rinsed from the model and placed on nitrocellulose filters after the delivery. A new novel method was established for deposition data acquisition. The method is based on a principle of image analysis. The images were captured by high definition camera attached to a phase contrast microscope. Results of new method were compared with standard PCM method, which follows methodology NIOSH 7400, and a good match was found. The new method was found applicable for evaluation of fibers and deposition fraction and deposition efficiency were calculated afterwards.

  10. An assessment of radiotherapy dosimeters based on CVD grown diamond

    CERN Document Server

    Ramkumar, S; Conway, J; Whitehead, A J; Sussman, R S; Hill, G; Walker, S

    2001-01-01

    Diamond is potentially a very suitable material for use as a dosimeter for radiotherapy. Its radiation hardness, the near tissue equivalence and chemical inertness are some of the characteristics of diamond, which make it well suited for its application as a dosimeter. Recent advances in the synthesis of diamond by chemical vapour deposition (CVD) technology have resulted in the improvement in the quality of material and increased its suitability for radiotherapy applications. We report in this paper, the response of prototype dosimeters based on two different types (CVD1 and CVD2) of CVD diamond to X-rays. The diamond devices were assessed for sensitivity, dependence of response on dose and dose rate, and compared with a Scanditronix silicon photon diode and a PTW natural diamond dosimeter. The diamond devices of CVD1 type showed an initial increase in response with dose, which saturates after approx 6 Gy. The diamond devices of CVD2 type had a response at low fields (1162.8 V/cm), the CVD2-type devices show...

  11. Study of CVD diamond layers with amorphous carbon admixture by Raman scattering spectroscopy

    Directory of Open Access Journals (Sweden)

    Dychalska Anna

    2015-12-01

    Full Text Available Raman spectroscopy is a most often used standard technique for characterization of different carbon materials. In this work we present the Raman spectra of polycrystalline diamond layers of different quality, synthesized by Hot Filament Chemical Vapor Deposition method (HF CVD. We show how to use Raman spectroscopy for the analysis of the Raman bands to determine the structure of diamond films as well as the structure of amorphous carbon admixture. Raman spectroscopy has become an important technique for the analysis of CVD diamond films. The first-order diamond Raman peak at ca. 1332 cm−1 is an unambiguous evidence for the presence of diamond phase in the deposited layer. However, the existence of non-diamond carbon components in a CVD diamond layer produces several overlapping peaks in the same wavenumber region as the first order diamond peak. The intensities, wavenumber, full width at half maximum (FWHM of these bands are dependent on quality of diamond layer which is dependent on the deposition conditions. The aim of the present work is to relate the features of diamond Raman spectra to the features of Raman spectra of non-diamond phase admixture and occurrence of other carbon structures in the obtained diamond thin films.

  12. Atomic scale KMC simulation of {100} oriented CVD diamond film growth under low substrate temperature—Part Ⅰ Simulation of CVD diamond film growth under Joe-Badgwell-Hauge model

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The growth of {100} oriented CVD (Chemical Vapor Deposition)diamond film under Joe-Badgwell-Hauge (J-B-H) model is simulated at atomic scale by using revised KMC (Kinetic Monte Carlo) method. The results show that: (1) under Joe's model, the growth mechanism from single carbon species is suitable for the growth of {100} oriented CVD diamond film in low temperature; (2) the deposition rate and surface roughness () under Joe's model are influenced intensively by temperature ()and not evident bymass fraction of atom chlorine; (3)the surface roughness increases with the deposition rate, i.e. the film quality becomes worse with elevated temperature, in agreement with Grujicic's prediction; (4) the simulation results cannot make sure the role of single carbon insertion.

  13. Atomic scale KMC simulation of {100} oriented CVD diamond film growth under low substrate temperature—Part I simulation of CVD diamond film growth under Joe—Badgwell—Hauge model

    Institute of Scientific and Technical Information of China (English)

    Xizhong; YuZhang; 等

    2002-01-01

    The growth of {100} oriented CVD( Chemical Vapor Deposition) diamond film under Joe-Badgwell-Hauge(J-B-H) model is simulated at atomic scale by using revised KMC(Kinetic Monte Carlo)method.The results show that:(1) under Joe's model,the growth mechanism from single carbon species is suitable for the growth of {100} oriented CVD diamond film in low temperature;(2) the deposition rate and surface roughness(Rq) under Joe's model are influenced intensively by temperature(Ts) and not evident bymass fraction Wc1 of atom chlorine;(3) the surface roughness increases with the deposition rate.i.e.the film quality becomes worse with elevated temperature,in agreement with Grujicic's prediction;(4) the simulation results cannot make sure the role of single carbon insertion.

  14. Method for electrostatic deposition of graphene on a substrate

    Science.gov (United States)

    Sumanasekera, Gamini (Inventor); Sidorov, Anton N. (Inventor); Ouseph, P. John (Inventor); Yazdanpanah, Mehdi M. (Inventor); Cohn, Robert W. (Inventor); Jalilian, Romaneh (Inventor)

    2010-01-01

    A method for electrostatic deposition of graphene on a substrate comprises the steps of securing a graphite sample to a first electrode; electrically connecting the first electrode to a positive terminal of a power source; electrically connecting a second electrode to a ground terminal of the power source; placing the substrate over the second electrode; and using the power source to apply a voltage, such that graphene is removed from the graphite sample and deposited on the substrate.

  15. Fabricating Large-Area Sheets of Single-Layer Graphene by CVD

    Science.gov (United States)

    Bronikowski, Michael; Manohara, Harish

    2008-01-01

    This innovation consists of a set of methodologies for preparing large area (greater than 1 cm(exp 2)) domains of single-atomic-layer graphite, also called graphene, in single (two-dimensional) crystal form. To fabricate a single graphene layer using chemical vapor deposition (CVD), the process begins with an atomically flat surface of an appropriate substrate and an appropriate precursor molecule containing carbon atoms attached to substituent atoms or groups. These molecules will be brought into contact with the substrate surface by being flowed over, or sprayed onto, the substrate, under CVD conditions of low pressure and elevated temperature. Upon contact with the surface, the precursor molecules will decompose. The substituent groups detach from the carbon atoms and form gas-phase species, leaving the unfunctionalized carbon atoms attached to the substrate surface. These carbon atoms will diffuse upon this surface and encounter and bond to other carbon atoms. If conditions are chosen carefully, the surface carbon atoms will arrange to form the lowest energy single-layer structure available, which is the graphene lattice that is sought. Another method for creating the graphene lattice includes metal-catalyzed CVD, in which the decomposition of the precursor molecules is initiated by the catalytic action of a catalytic metal upon the substrate surface. Another type of metal-catalyzed CVD has the entire substrate composed of catalytic metal, or other material, either as a bulk crystal or as a think layer of catalyst deposited upon another surface. In this case, the precursor molecules decompose directly upon contact with the substrate, releasing their atoms and forming the graphene sheet. Atomic layer deposition (ALD) can also be used. In this method, a substrate surface at low temperature is covered with exactly one monolayer of precursor molecules (which may be of more than one type). This is heated up so that the precursor molecules decompose and form one

  16. Study of CVD Method for Manufacturing 6.5%Si Steel Sheet%化学气相沉积法制备6.5%Si高硅钢的研究

    Institute of Scientific and Technical Information of China (English)

    王爱华; 刘畅

    2011-01-01

    采用化学气相沉积(CVD)渗硅处理工艺连续制备6.5%Si高硅钢,具有优质的软磁性能,通过理论研究化学反应并且用简单的试验设备做进一步的探讨.根据试验的结果对连续制备6.5%Si高硅钢的CVD工艺构造提出全面、有效的建议,实现制备6.5%Si高硅钢系统.%CVD method for continuously manufacturing 6. 5%Si Steel Sheet has excellent soft magnetic. Carried out a theoretical study of related chemical reaction and performing basic research with a simple test apparatus. Based on the results, finally proposed an overall process configuration to realize such a production-CVD method for continuously manufacturing 6. 5% Si Steel Sheet.

  17. Vitroceramic interface deposited on titanium substrate by pulsed laser deposition method.

    Science.gov (United States)

    Voicu, Georgeta; Miu, Dana; Dogaru, Ionut; Jinga, Sorin Ion; Busuioc, Cristina

    2016-08-30

    Pulsed laser deposition (PLD) method was used to obtain biovitroceramic thin film coatings on titanium substrates. The composition of the targets was selected from SiO2-CaO-P2O5-(CaF2) systems and the corresponding masses were prepared using the sol-gel method. The depositions were performed in oxygen atmosphere (100mTorr), while the substrates were heated at 400°C. The PLD deposited films were analysed through different experimental techniques: X-ray diffraction, scanning (SEM, EDX) and transmission (HRTEM, SAED) electron microscopy and infra-red spectroscopy coupled with optical microscopy. They were also biologically tested by in vitro cell culture and the contact angle was determined. The bioevaluation results indicate a high biocompatibilty of the obtained materials, demonstrating their potential use for biomedical applications.

  18. Method and system for continuous atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Elam, Jeffrey W.; Yanguas-Gil, Angel; Libera, Joseph A.

    2017-03-21

    A system and method for continuous atomic layer deposition. The system and method includes a housing, a moving bed which passes through the housing, a plurality of precursor gases and associated input ports and the amount of precursor gases, position of the input ports, and relative velocity of the moving bed and carrier gases enabling exhaustion of the precursor gases at available reaction sites.

  19. A Review of the Properties and CVD Synthesis of Coiled Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Dóra Fejes

    2010-04-01

    Full Text Available The CVD route for carbon nanotube production has become a popular method to make large amounts of multiwall carbon nanotubes. The structure, morphology and size of carbon materials depend critically on the catalyst preparation and deposition conditions. According to current knowledge, CVD method is the only process which can produce carbon nanocoils. These nanocoils are perfect candidates for nanotechnology applications. One might indeed hope that these coils would have the extraordinary stiffness displayed by straight nanotubes. Based on theoretical studies, regular coiled nanotubes exhibit exceptional mechanical, electrical, and magnetic properties due to the combination of their peculiar helical morphology and the fascinating properties of nanotubes. In spite of its technological interest, relatively low attention has been paid to this special field. In this paper we attempt to summarize results obtained until now.

  20. A new pulsed laser deposition technique: scanning multi-component pulsed laser deposition method.

    Science.gov (United States)

    Fischer, D; de la Fuente, G F; Jansen, M

    2012-04-01

    The scanning multi-component pulsed laser deposition (PLD) method realizes uniform depositions of desired coatings by a modified pulsed laser deposition process, preferably with a femto-second laser-system. Multi-component coatings (single or multilayered) are thus deposited onto substrates via laser induced ablation of segmented targets. This is achieved via horizontal line-scanning of a focused laser beam over a uniformly moving target's surface. This process allows to deposit the desired composition of the coating simultaneously, starting from the different segments of the target and adjusting the scan line as a function of target geometry. The sequence and thickness of multilayers can easily be adjusted by target architecture and motion, enabling inter/intra layer concentration gradients and thus functional gradient coatings. This new, simple PLD method enables the achievement of uniform, large-area coatings. Case studies were performed with segmented targets containing aluminum, titanium, and niobium. Under the laser irradiation conditions applied, all three metals were uniformly ablated. The elemental composition within the rough coatings obtained was fixed by the scanned area to Ti-Al-Nb = 1:1:1. Crystalline aluminum, titanium, and niobium were found to coexist side by side at room temperature within the substrate, without alloy formation up to 600 °C.

  1. Catalytic Synthesis of Substrate-Free, Aligned and Tailored High Aspect Ratio Multiwall Carbon Nanotubes in an Ultrasonic Atomization Head CVD Reactor

    OpenAIRE

    Fahad Ali Rabbani; Zuhair Omar Malaibari; Muataz Ali Atieh; Ammar Jamie

    2016-01-01

    Chemical vapor deposition (CVD) method has proven its benchmark, over other methods, for the production of different types of carbon nanotubes (CNT) on commercial and lab scale. In this study, an injection vertical CVD reactor fitted with an ultrasonic atomization head was used in a pilot-plant scale (height 274 cm, radius 25 cm) for semicontinuous production of multiwall carbon nanotubes (MWCNTs). p-Xylene was used as a hydrocarbon precursor in which ferrocene was dissolved and provided the ...

  2. Room Temperature Growth of Hydrogenated Amorphous Silicon Films by Dielectric Barrier Discharge Enhanced CVD

    Institute of Scientific and Technical Information of China (English)

    GUO Yu; ZHANG Xiwen; HAN Gaorong

    2007-01-01

    Hydrogenated amorphous silicon (a-Si:H) films were deposited on Si (100) and glass substrates by dielectric barrier discharge enhanced chemical vapour deposition (DBD-CVD)in (SiH4+H2) atmosphere at room temperature.Results of the thickness measurement,SEM (scanning electron microscope),Raman,and FTIR (Fourier transform infrared spectroscopy) show that with the increase in the applied peak voltage,the deposition rate and network order of the films increase,and the hydrogen bonding configurations mainly in di-hydrogen (Si-H2) and poly hydrogen (SiH2)n are introduced into the films.The UV-visible transmission spectra show that with the decrease in Sill4/ (SiH4+H2) the thin films'band gap shifts from 1.92 eV to 2.17 eV.These experimental results are in agreement with the theoretic analysis of the DBD discharge.The deposition of a-Si:H films by the DBD-CVD method as reported here for the first time is attractive because it allows fast deposition of a-Si:H films on large-area low-melting-point substrates and requires only a low cost of production without additional heating or pumping equipment.

  3. CVD Diamond Sensors In Detectors For High Energy Physics

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00334150; Trischuk, William

    At the end of the next decade an upgrade of the Large Hadron Collider (LHC) to High Luminosity LHC (HL-LHC) is planned which requires the development of new radiation tolerant sensor technology. Diamond is an interesting material for use as a particle detector in high radiation environments. The large band gap ($5.47\\,\\text{eV}$) and the large displacement energy suggest that diamond is a radiation tolerant detector material. In this Thesis the capability of Chemical Vapor Deposition (CVD) diamond as such a sensor technology is investigated. The radiation damage constant for $800\\,\\text{MeV}$ protons is measured using single crystalline CVD (scCVD) and polycrystalline CVD (pCVD) diamonds irradiated to particle fluences up to $12 \\times 10^{15}\\,\\text{p/cm}^2$. In addition the signal response of a pCVD diamond detector after an irradiation to $12 \\times 10^{15}\\,\\text{p/cm}^2$ is investigated to determine if such a detector can be operated efficiently in the expected HL-LHC environment. By using electrodes em...

  4. Enhancement of the Electrical Properties of CVD-Grown Graphene with Ascorbic Acid Treatment

    Science.gov (United States)

    Tang, Chunmiao; Chen, Zhiying; Zhang, Haoran; Zhang, Yaqian; Zhang, Yanhui; Sui, Yanping; Yu, Guanghui; Cao, Yijiang

    2016-02-01

    Ascorbic acid was used to modify to chemical vapor deposition (CVD)-grown graphene films transferred onto SiO2 substrate. Residual polymer (polymethyl methacrylate), Fe3+, Cl-, H2O, and O2 affected the electrical and thermal properties on graphene during the transfer or device fabrication processes. Exposure of transferred graphene to ascorbic acid resulted in significantly enhanced electrical properties with increased charge carrier mobility. All devices exhibited more than 30% improvement in room temperature carrier mobility in air. The carrier mobility of the treated graphene did not significantly decrease in 21 days. This result can be attributed to electron donation to graphene through the -OH functional group in ascorbic acid that is absorbed in graphene. This work provides a method to enhance the electrical properties of CVD-grown graphene.

  5. Synthesis of Few-Layer Graphene Using DC PE-CVD

    Science.gov (United States)

    Kim, Jeong Hyuk; Castro, Edward Joseph D.; Hwang, Yong Gyoo; Lee, Choong Hun

    2011-12-01

    Few layer graphene (FLG) had been successfully grown on polycrystalline Ni films or foils on a large scale using DC Plasma Enhanced Chemical Vapor Deposition (DC PE-CVD) as a result of the Raman spectra drawn out of the sample. The size of graphene films is dependent on the area of the Ni film as well as the DC PE-CVD chamber size. Synthesis time has an effect on the quality of graphene produced. However, further analysis and experiments must be pursued to further identify the optimum settings and conditions of producing better quality graphene. Applied plasma voltage on the other hand, had an influence on the minimization of defects in the graphene grown. It has also presented a method of producing a free standing PMMA/graphene membrane on a FeCl3(aq) solution which could then be transferred to a desired substrate.

  6. A Comparative Study of Three Different Chemical Vapor Deposition Techniques of Carbon Nanotube Growth on Diamond Films

    Directory of Open Access Journals (Sweden)

    Betty T. Quinton

    2013-01-01

    Full Text Available This paper compares between the methods of growing carbon nanotubes (CNTs on diamond substrates and evaluates the quality of the CNTs and the interfacial strength. One potential application for these materials is a heat sink/spreader for high-power electronic devices. The CNTs and diamond substrates have a significantly higher specific thermal conductivity than traditional heat sink/spreader materials making them good replacement candidates. Only limited research has been performed on these CNT/diamond structures and their suitability of different growth methods. This study investigates three potential chemical vapor deposition (CVD techniques for growing CNTs on diamond: thermal CVD (T-CVD, microwave plasma-enhanced CVD (MPE-CVD, and floating catalyst thermal CVD (FCT-CVD. Scanning electron microscopy (SEM and high-resolution transmission electron microscopy (TEM were used to analyze the morphology and topology of the CNTs. Raman spectroscopy was used to assess the quality of the CNTs by determining the ID/IG peak intensity ratios. Additionally, the CNT/diamond samples were sonicated for qualitative comparisons of the durability of the CNT forests. T-CVD provided the largest diameter tubes, with catalysts residing mainly at the CNT/diamond interface. The MPE-CVD process yielded non uniform defective CNTs, and FCT-CVD resulted in the smallest diameter CNTs with catalyst particles imbedded throughout the length of the nanotubes.

  7. Development of atmospheric pressure CVD processes for highquality transparent conductive oxides

    NARCIS (Netherlands)

    Graaf, A. de; Deelen, J. van; Poodt, P.W.G.; Mol, A.M.B. van; Spee, C.I.M.A.; Grob, F.; Kuypers, A.

    2010-01-01

    For the past decade TNO has been involved in the research and development of atmospheric pressure CVD (APCVD) and plasma enhanced CVD (PECVD) processes for deposition of transparent conductive oxides (TCO), such as tin oxide and zinc oxide. It is shown that by combining precursor development, fundam

  8. Surface analysis of CVD diamond exposed to fusion plasma

    NARCIS (Netherlands)

    Porro, S.; De Temmerman, G.; MacLaren, D. A.; Lisgo, S.; Rudakov, D. L.; Westerhout, J.; Wiora, M.; John, P.; Villalpando, I.; Wilson, J. I. B.

    2010-01-01

    Microcrystalline undoped and heavily boron-doped polycrystalline diamond layers have been deposited on various substrates by hot filament CVD and exposed to hydrogen plasma in a linear plasma reactor (Pilot-PSI, The Netherlands) that simulates the high flux and high density plasma conditions of toka

  9. High collection efficiency CVD diamond alpha detectors

    Energy Technology Data Exchange (ETDEWEB)

    Bergonzo, P.; Foulon, F.; Marshall, R.D.; Jany, C.; Brambilla, A. [CEA/Saclay, Gif-sur-Yvette (France); McKeag, R.D.; Jackman, R.B. [University College London (United Kingdom). Electronic and Electrical Engineering Dept.

    1998-06-01

    Advances in Chemical Vapor Deposited (CVD) diamond have enabled the routine use of this material for sensor device fabrication, allowing exploitation of its unique combination of physical properties (low temperature susceptibility (> 500 C), high resistance to radiation damage (> 100 Mrad) and to corrosive media). A consequence of CVD diamond growth on silicon is the formation of polycrystalline films which has a profound influence on the physical and electronic properties with respect to those measured on monocrystalline diamond. The authors report the optimization of physical and geometrical device parameters for radiation detection in the counting mode. Sandwich and co-planar electrode geometries are tested and their performances evaluated with regard to the nature of the field profile and drift distances inherent in such devices. The carrier drift length before trapping was measured under alpha particles and values as high as 40% of the overall film thickness are reported. Further, by optimizing the device geometry, they show that a gain in collection efficiency, defined as the induced charge divided by the deposited charge within the material, can be achieved even though lower bias values are used.

  10. DLC Films Deposited by the DC PACVD Method

    Directory of Open Access Journals (Sweden)

    D. Palamarchuk

    2003-01-01

    Full Text Available DLC (Diamond-Like Carbon coatings have been suggested as protective surface layers against wear. However hard DLC coatings, especially those of greater thickness, have poor adhesion to substrates. We have used several ways to increase the adhesion of DLC coatings prepared by the PACVD (Plasma Assisted Chemical Vapour Deposition method on steel substrates. One of these is the DC PACVD method for preparing DLC films.

  11. DLC Films Deposited by the DC PACVD Method

    OpenAIRE

    D. Palamarchuk; M. Zoriy; J. Gurovič; F. Černý; S. Konvičková; I. Hüttel

    2003-01-01

    DLC (Diamond-Like Carbon) coatings have been suggested as protective surface layers against wear. However hard DLC coatings, especially those of greater thickness, have poor adhesion to substrates. We have used several ways to increase the adhesion of DLC coatings prepared by the PACVD (Plasma Assisted Chemical Vapour Deposition) method on steel substrates. One of these is the DC PACVD method for preparing DLC films.

  12. Synthesis of graphene by cobalt-catalyzed decomposition of methane in plasma-enhanced CVD: Optimization of experimental parameters with Taguchi method

    Science.gov (United States)

    Mehedi, H.-A.; Baudrillart, B.; Alloyeau, D.; Mouhoub, O.; Ricolleau, C.; Pham, V. D.; Chacon, C.; Gicquel, A.; Lagoute, J.; Farhat, S.

    2016-08-01

    This article describes the significant roles of process parameters in the deposition of graphene films via cobalt-catalyzed decomposition of methane diluted in hydrogen using plasma-enhanced chemical vapor deposition (PECVD). The influence of growth temperature (700-850 °C), molar concentration of methane (2%-20%), growth time (30-90 s), and microwave power (300-400 W) on graphene thickness and defect density is investigated using Taguchi method which enables reaching the optimal parameter settings by performing reduced number of experiments. Growth temperature is found to be the most influential parameter in minimizing the number of graphene layers, whereas microwave power has the second largest effect on crystalline quality and minor role on thickness of graphene films. The structural properties of PECVD graphene obtained with optimized synthesis conditions are investigated with Raman spectroscopy and corroborated with atomic-scale characterization performed by high-resolution transmission electron microscopy and scanning tunneling microscopy, which reveals formation of continuous film consisting of 2-7 high quality graphene layers.

  13. Engineered CVD Diamond Coatings for Machining and Tribological Applications

    Science.gov (United States)

    Dumpala, Ravikumar; Chandran, Maneesh; Ramachandra Rao, M. S.

    2015-07-01

    Diamond is an allotropes of carbon and is unique because of its extreme hardness (~100 GPa), low friction coefficient (fracture toughness can be tuned by controlling the grain size of the coatings from a few microns to a few nanometers. In this review, characteristics and performance of the CVD diamond coatings deposited on cemented tungsten carbide (WC-Co) substrates were discussed with an emphasis on WC-Co grade selection, substrate pretreatment, nanocrystallinity and microcrystallinity of the coating, mechanical and tribological characteristics, coating architecture, and interfacial adhesion integrity. Engineered coating substrate architecture is essential for CVD diamond coatings to perform well under harsh and highly abrasive machining and tribological conditions.

  14. A novel electroless silver depositing method for magnesium alloys

    Institute of Scientific and Technical Information of China (English)

    ZHAO Hui; CUI Jian-zhong

    2006-01-01

    Depositing silver on magnesium alloy by both electroless plating and organic coatings was studied. The organic coating was made by immersing samples in organosilicon heat-resisting varnish. In this method the organic coating acts as interlayer between the substrate and silver film. When the reaction starts, silver deposits directly on the interlayer. X-ray diffraction and SEM analysis were used to determine the composition and morphology of the interlayer and silver film. The potentiodynamic polarization curves for corrosion studies of coated magnesium alloys were performed in a corrosive environment of 3.5% NaCl(mass fraction) at neutral pH (6.9). The results indicate that compared with the substrate, the corrosion resistance of coated magnesium alloys increases greatly. Moreover, the method proposed in this work is environmentally friendly, non-toxic chemicals were used. In addition, it provides a new concept for the corrosion inhibition of magnesium alloys.

  15. Methods of preparing deposits containing iron oxides for recycling

    Directory of Open Access Journals (Sweden)

    T. Lis

    2013-04-01

    Full Text Available The metallurgical industry is one of the largest sources of wastes. Some of them, however, owing to their content of metals such as zinc or iron, may become valuable secondary raw materials. In order to achieve that purpose, they require appropriate preparation. This article provides a discussion on the methods of preparation of scrap from steelworks, namely deposits containing iron oxides, enabling their recycling.

  16. Laser-Directed CVD 3D Printing of Refractory Metal Rocket Propulsion Hardware Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In this project, Ultramet will develop a three-dimensional (3D) laser-directed chemical vapor deposition (CVD) additive manufacturing system to build free-form...

  17. Present limitations of CVD diamond detectors for IMRT applications

    Energy Technology Data Exchange (ETDEWEB)

    De Angelis, C. [Dipartimento di Tecnologie e Salute, Istituto Superiore di Sanita and INFN, Viale regina Elena 299, 00161 Rome (Italy)], E-mail: cinzia.deangelis@iss.it; Casati, M. [Dipartimento di Fisiopatologia dell' Universita and INFN, Florence (Italy); Bruzzi, M. [Dipartimento di Energetica dell' Universita and INFN, Florence (Italy); Onori, S. [Dipartimento di Tecnologie e Salute, Istituto Superiore di Sanita and INFN, Viale regina Elena 299, 00161 Rome (Italy); Bucciolini, M. [Dipartimento di Fisiopatologia dell' Universita and INFN, Florence (Italy)

    2007-12-11

    The aim of the work was to test the suitability of chemical vapor deposited (CVD) diamond detectors for dosimetry in IMRT fields. We used in-house CVD detectors prepared with state-of-the-art polycrystalline diamond films (Element Six Ltd., UK). The parameters considered were time stability, dynamic response, dose-rate dependence and energy dependence. Output factors and TPR were measured in conventional photon fields and dose measurements were performed in IMRT fields using the step-and-shoot technique. Results prove that CVD diamond detectors are suitable for dosimetry in conventional treatments, but they still do not fit the IMRT dosimetry requirements, mainly because of their slow dynamic response. In particular, the slow dynamics affects linearity at low Monitor Units and renders it impossible to follow the sharp transients of IMRT fields. Time stability and dose-rate dependence as well must be improved to reduce their influence on dose assessment.

  18. Direct CVD Graphene Growth on Semiconductors and Dielectrics for Transfer-Free Device Fabrication.

    Science.gov (United States)

    Wang, Huaping; Yu, Gui

    2016-07-01

    Graphene is the most broadly discussed and studied two-dimensional material because of its preeminent physical, mechanical, optical, and thermal properties. Until now, metal-catalyzed chemical vapor deposition (CVD) has been widely employed for the scalable production of high-quality graphene. However, in order to incorporate the graphene into electronic devices, a transfer process from metal substrates to targeted substrates is inevitable. This process usually results in contamination, wrinkling, and breakage of graphene samples - undesirable in graphene-based technology and not compatible with industrial production. Therefore, direct graphene growth on desired semiconductor and dielectric substrates is considered as an effective alternative. Over the past years, there have been intensive investigations to realize direct graphene growth using CVD methods without the catalytic role of metals. Owing to the low catalytic activity of non-metal substrates for carbon precursor decomposition and graphene growth, several strategies have been designed to facilitate and engineer graphene fabrication on semiconductors and insulators. Here, those developed strategies for direct CVD graphene growth on semiconductors and dielectrics for transfer-free fabrication of electronic devices are reviewed. By employing these methods, various graphene-related structures can be directly prepared on desired substrates and exhibit excellent performance, providing versatile routes for varied graphene-based materials fabrication.

  19. Fabrication and characteristics of self-assembly nano-polystyrene films by laser induced CVD

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Tingting [Department of Applied Physics, Chongqing University, Chongqing 401331 (China); Science and Technology on Plasma Physics Laboratory, Research Center of Laser Fusion, CAEP, Mianyang 621900 (China); Cai, Congzhong [Department of Applied Physics, Chongqing University, Chongqing 401331 (China); Peng, Liping [Science and Technology on Plasma Physics Laboratory, Research Center of Laser Fusion, CAEP, Mianyang 621900 (China); Wu, Weidong, E-mail: wuweidongding@163.com [Science and Technology on Plasma Physics Laboratory, Research Center of Laser Fusion, CAEP, Mianyang 621900 (China)

    2013-10-01

    The self-assembly nano-polystyrene (PS) films have been prepared by laser induced CVD at room temperature. The XPS, Raman and UV–vis absorption spectra all indicated that the films were PS. The optical properties, microstructure and controllable nanostructure of PS films have been investigated. Dewetting-like microstructure in PS films was investigated and uniform island structures with a diameter of about 200 nm were observed at the deposition pressure of 14 Pa. The films possess good toughness and precisely controlled thicknesses. The free-standing PS films with thickness of 10 nm could be obtained by this method though a series of process.

  20. Superhydrophobic aluminium-based surfaces: Wetting and wear properties of different CVD-generated coating types

    Energy Technology Data Exchange (ETDEWEB)

    Thieme, M., E-mail: michael.thieme@tu-dresden.de [Technische Universität Dresden, Institute of Materials Science, 01062 Dresden (Germany); Streller, F., E-mail: streller@seas.upenn.edu [Technische Universität Dresden, Institute of Materials Science, 01062 Dresden (Germany); Simon, F., E-mail: frsimon@ipfdd.de [Leibniz-Institut für Polymerforschung Dresden, Postfach 120 411, 01005 Dresden (Germany); Frenzel, R., E-mail: frenzelr@ipfdd.de [Leibniz-Institut für Polymerforschung Dresden, Postfach 120 411, 01005 Dresden (Germany); White, A.J. [GVD Corporation, 45 Spinelli Place, Cambridge, MA 02138 (United States)

    2013-10-15

    In view of generating superhydrophobic aluminium-based surfaces, this work presents further results for the combination of anodic oxidation as the primary pretreatment method and chemical vapour deposition (CVD) variants for chemical modification producing coatings of 250–1000 nm thickness. In detail, CVD involved the utilisation of i – hexafluoropropylene oxide as precursor within the hot filament CVD process for the deposition of poly(tetrafluoroethylene) coatings at alternative conditions (PTFE-AC) and ii – 1,3,5-trivinyltrimethylcyclotrisiloxane for the deposition of polysiloxane coatings (PSi) by initiated CVD. The substrate material was Al Mg1 subjected to usual or intensified sulphuric acid anodisation pretreatments (SAAu, SAAi, respectively) affording various degrees of surface micro-roughness (SAAu < SAAi) to the oxidic layers. Performance characteristics were evaluated in the original as-coated states and after standardised artificial weathering and/or mild wear testing. Superhydrophobicity (SH) was observed with the system SAAi + PTFE-AC similarly to former findings with the standard hot filament CVD PTFE coating variant (SAAi + PTFE-SC). The results indicated that the specific coating morphology made an important contribution to the water-repellency, because even some of the SAAu-based samples tended to reveal SH. Subjecting samples to weathering treatment resulted in a general worsening of the wetting behaviour, primarily limited to the receding contact angles. These tendencies were correlated with the chemical composition of the sample surfaces as analysed by X-ray photoelectron spectroscopy. The wear tests showed, as evaluated by scanning electron microscopy and contact angle measurement, that the PTFE coatings were relatively sensitive to friction. This was connected with a dramatic deterioration of the water-repelling properties. PSi-coated surfaces generally showed rather poor water-repellency, but this coating type was surprisingly

  1. Predicting sulphur and nitrogen deposition using a simple statistical method

    Science.gov (United States)

    Oulehle, Filip; Kopáček, Jiří; Chuman, Tomáš; Černohous, Vladimír; Hůnová, Iva; Hruška, Jakub; Krám, Pavel; Lachmanová, Zora; Navrátil, Tomáš; Štěpánek, Petr; Tesař, Miroslav; Evans, Christopher D.

    2016-09-01

    Data from 32 long-term (1994-2012) monitoring sites were used to assess temporal development and spatial variability of sulphur (S) and inorganic nitrogen (N) concentrations in bulk precipitation, and S in throughfall, for the Czech Republic. Despite large variance in absolute S and N concentration/deposition among sites, temporal coherence using standardised data (Z score) was demonstrated. Overall significant declines of SO4 concentration in bulk and throughfall precipitation, as well as NO3 and NH4 concentration in bulk precipitation, were observed. Median Z score values of bulk SO4, NO3 and NH4 and throughfall SO4 derived from observations and the respective emission rates of SO2, NOx and NH3 in the Czech Republic and Slovakia showed highly significant (p Z score values were calculated for the whole period 1900-2012 and then back-transformed to give estimates of concentration for the individual sites. Uncertainty associated with the concentration calculations was estimated as 20% for SO4 bulk precipitation, 22% for throughfall SO4, 18% for bulk NO3 and 28% for bulk NH4. The application of the method suggested that it is effective in the long-term reconstruction and prediction of S and N deposition at a variety of sites. Multiple regression modelling was used to extrapolate site characteristics (mean precipitation chemistry and its standard deviation) from monitored to unmonitored sites. Spatially distributed temporal development of S and N depositions were calculated since 1900. The method allows spatio-temporal estimation of the acid deposition in regions with extensive monitoring of precipitation chemistry.

  2. Polymer Layers by Initiated CVD for Thin Film Gas Barrier Encapsulation

    NARCIS (Netherlands)

    Spee, D.A.; Rath, J.K.; Schropp, R.E.I.

    2013-01-01

    In this chapter a thorough description of the initiated chemical vapor deposition (iCVD) process will be given, concentrating on molecular weight and deposition rate of the deposited polymer, which are essential for largescale application in hybrid gas barriers. Practical applications of coatings by

  3. A platform for large-scale graphene electronics--CVD growth of single-layer graphene on CVD-grown hexagonal boron nitride.

    Science.gov (United States)

    Wang, Min; Jang, Sung Kyu; Jang, Won-Jun; Kim, Minwoo; Park, Seong-Yong; Kim, Sang-Woo; Kahng, Se-Jong; Choi, Jae-Young; Ruoff, Rodney S; Song, Young Jae; Lee, Sungjoo

    2013-05-21

    Direct chemical vapor deposition (CVD) growth of single-layer graphene on CVD-grown hexagonal boron nitride (h-BN) film can suggest a large-scale and high-quality graphene/h-BN film hybrid structure with a defect-free interface. This sequentially grown graphene/h-BN film shows better electronic properties than that of graphene/SiO2 or graphene transferred on h-BN film, and suggests a new promising template for graphene device fabrication.

  4. Comparison of galvanic displacement and electroless methods for deposition of gold nanoparticles on synthetic calcite

    Indian Academy of Sciences (India)

    Chamarthi K Srikanth; P Jeevanandam

    2012-11-01

    Gold nanoparticles have been deposited on synthetic calcite substrate by galvanic displacement reaction and electroless deposition methods. A comparative study has shown that electroless deposition is superior compared to galvanic displacement reaction for uniform deposition of gold nanoparticles on calcite. Characterization of the samples, prepared by two different deposition methods, was carried out by X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy (FE–SEM) and diffuse reflectance spectroscopy (DRS) measurements. FE–SEM studies prove that smaller nanoparticles of gold are deposited uniformly on calcite if electroless deposition method was employed and DRS measurements show the characteristic surface plasmon resonance of gold nanoparticles.

  5. Interface reactions at TiN/HfSiON gate stacks: Dependence on the electrode structure and deposition method

    Directory of Open Access Journals (Sweden)

    Shiniti Yoshida et al

    2007-01-01

    Full Text Available We systematically investigated intrinsic and extrinsic thermal reactions at TiN/HfSiON gate stacks. The formation of an ultrathin TiO2 interlayer was found to be an intrinsic reaction at the metal/insulator interface, but growth of SiO2 underlayers between HfSiON and Si substrates, which determines the electrical thickness of metal-oxide-semiconductor (MOS devices, depends on the structure and deposition method of the gate electrodes. Physical vapor deposition (PVD grown TiN electrodes covered with W overlayers exhibited excellent thermal stability at up to 1000 °C. Formation of ultrathin TiO2 interlayers reduced gate leakage current (Ig, and growth of the oxide underlayer was suppressed by less than a few angstroms even for 1000 °C annealing. In contrast, we found that halogen impurities within CVD-grown metal electrodes enhance interface SiO2 growth, resulting in deterioration of equivalent oxide thickness (EOT versus Ig characteristics of the gate stacks.

  6. Plasma-Enhanced Chemical Vapor Deposition as a Method for the Deposition of Peptide Nanotubes

    Science.gov (United States)

    2013-09-17

    peptide nanotubes, plasma-enhanced chemical vapor deposition, nano assembly 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT SAR 18...Using physical vapor deposition ( PVD ) well-ordered assemblies of peptide nanotubes (PNTs) composed of dipeptide subunits are obtained on various...for the deposition of thin films (Figure 1b). A. B. Figure 1. (a) Illustration of physical vapor deposition ( PVD ) process of diphenylalanine

  7. Microfabrication of Tungsten, Molybdenum and Tungsten Carbide Rods by Laser-Assisted CVD

    OpenAIRE

    Björklund, Kajsa

    2001-01-01

    Thin films of refractory metals and carbides have been studied extensively over many years because of their wide range of application. The two major techniques used are Chemical Vapour Deposition (CVD) and Physical Vapour Deposition (PVD). These can result in the deposition of two-dimensional blanket or patterned thin films. Laser-assisted Chemical Vapour Deposition (LCVD) can provide a maskless alternative for localised deposition in two and three dimensions. This thesis describes LCVD of mi...

  8. Adhesive strength of CVD diamond thin films quantitatively measured by means of the bulge and blister test

    Institute of Scientific and Technical Information of China (English)

    Daohui Xiang; Ming Chen; Yuping Ma; Fanghong Sun

    2008-01-01

    Large advancement has been made in understanding the nucleation and growth of chemical vapor deposition (CVD) diamond, but the adhesion of CVD diamond to substrates is poor and there is no good method for quantitative evaluation of the adhesive strength. The blister test is a potentially powerful tool for characterizing the mechanical properties of diamond films. In this test, pressure was applied on a thin membrane and the out-of-plane deflection of the membrane center was measured. The Young's modulus, residual stress, and adhesive strength were simultaneously determined using the load-deflection behavior of a membrane. The free-standing window sample of diamond thin films was fabricated by means of photolithography and anisotropic wet etching. The research indicates that the adhesive strength of diamond thin films is 4.28±0.37J/m2. This method uses a simple apparatus, and the fabrication of samples is very easy.

  9. Liquid precursor for deposition of copper selenide and method of preparing the same

    Energy Technology Data Exchange (ETDEWEB)

    Curtis, Calvin J.; Miedaner, Alexander; Franciscus Antonius Maria Van Hest, Marinus; Ginley, David S.; Hersh, Peter A.; Eldada, Louay; Stanbery, Billy J.

    2015-09-08

    Liquid precursors containing copper and selenium suitable for deposition on a substrate to form thin films suitable for semiconductor applications are disclosed. Methods of preparing such liquid precursors and methods of depositing a precursor on a substrate are also disclosed.

  10. Catalytic CVD of SWCNTs at Low Temperatures and SWCNT Devices

    Science.gov (United States)

    Seidel, Robert; Liebau, Maik; Unger, Eugen; Graham, Andrew P.; Duesberg, Georg S.; Kreupl, Franz; Hoenlein, Wolfgang; Pompe, Wolfgang

    2004-09-01

    New results on the planar growth of single-walled carbon nanotubes (SWCNTs) by catalytic chemical vapor deposition (CVD) at low temperatures will be reported. Optimizing catalyst, catalyst support, and growth parameters yields SWCNTs at temperatures as low as 600 °C. Growth at such low temperatures largely affects the diameter distribution since coalescence of the catalyst is suppressed. A phenomenological growth model will be suggested for CVD growth at low temperatures. The model takes into account surface diffusion and is an alternative to the bulk diffusion based vapor-liquid-solid (VLS) model. Furthermore, carbon nanotubes field effect transistors based on substrate grown SWCNTs will be presented. In these devices good contact resistances could be achieved by electroless metal deposition or metal evaporation of the contacts.

  11. Hot-Wire Chemical Vapor Deposition of Few-Layer Graphene on Copper Substrates

    Science.gov (United States)

    Soler, Víctor-Manuel Freire; Badia-Canal, Jordi; Roca, Carles Corbella; Miralles, Esther Pascual; Serra, Enric Bertran; Bella, José-Luís Andújar

    2013-01-01

    Chemical vapor deposition (CVD) of graphene on copper is an efficient technology for producing high-quality graphene for large areas. The objective of this work is to deposit graphene/few-layer graphene (FLG) using different types of copper substrate by a new hot-wire CVD process. We carried out the processes at temperatures below 1000 °C with acetylene (C2H2) as a precursor gas. After a general characterization of the samples, the results mostly indicate the formation of FLG on copper samples by this method. Nevertheless, the presence of pure, crystalline, and sufficiently flat surfaces is needed for depositing high-quality graphene layers.

  12. Annealing dependence of residual stress and optical properties of TiO2 thin film deposited by different deposition methods.

    Science.gov (United States)

    Chen, Hsi-Chao; Lee, Kuan-Shiang; Lee, Cheng-Chung

    2008-05-01

    Titanium oxide (TiO(2)) thin films were prepared by different deposition methods. The methods were E-gun evaporation with ion-assisted deposition (IAD), radio-frequency (RF) ion-beam sputtering, and direct current (DC) magnetron sputtering. Residual stress was released after annealing the films deposited by RF ion-beam or DC magnetron sputtering but not evaporation, and the extinction coefficient varied significantly. The surface roughness of the evaporated films exceeded that of both sputtered films. At the annealing temperature of 300 degrees C, anatase crystallization occurred in evaporated film but not in the RF ion-beam or DC magnetron-sputtered films. TiO(2) films deposited by sputtering were generally more stable during annealing than those deposited by evaporation.

  13. Leakage current measurements of a pixelated polycrystalline CVD diamond detector

    OpenAIRE

    Zain, R.M.; Maneuski, D.; O'Shea, V.; Bates, R.; Blue, A.; Cunnigham, L.; Stehl, C.; Berderman, E.; Rahim, R. A.

    2013-01-01

    Diamond has several desirable features when used as a material for radiation detection. With the invention of synthetic growth techniques, it has become feasible to look at developing diamond radiation detectors with reasonable surface areas. Polycrystalline diamond has been grown using a chemical vapour deposition (CVD) technique by the University of Augsburg and detector structures fabricated at the James Watt Nanofabrication Centre (JWNC) in the University of Glasgow in order to produce pi...

  14. Doped Titanium Dioxide Films Prepared by Pulsed Laser Deposition Method

    Directory of Open Access Journals (Sweden)

    Juguang Hu

    2012-01-01

    Full Text Available TiO2 was intensively researched especially for photocatalystic applications. The nitrogen-doped TiO2 films prepared by pulsed laser deposition (PLD method were reviewed, and some recent new experimental results were also presented in this paper. A new optical transmission method for evaluating the photocatalystic activity was presented. The main results are (1 PLD method is versatile for preparing oxide material or complex component films with excellent controllability and high reproducibility. (2 Anatase nitrogen-doped TiO2 films were prepared at room temperature, 200°C, and 400°C by PLD method using novel ceramic target of mixture of TiN and TiO2. UV/Vis spectra, AFM, Raman spectra, and photocatalystic activity for decomposition of methyl orange (MO tests showed that visible light response was improved at higher temperature. (3 The automatic, continuous optical transmission autorecorder method is suitable for detecting the photodecomposition dynamic process of organic compound.

  15. Investigation of the Millimeter-Wave Plasma Assisted CVD Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Vikharev, A; Gorbachev, A; Kozlov, A; Litvak, A; Bykov, Y; Caplan, M

    2005-07-21

    A polycrystalline diamond grown by the chemical vapor deposition (CVD) technique is recognized as a unique material for high power electronic devices owing to unrivaled combination of properties such as ultra-low microwave absorption, high thermal conductivity, high mechanical strength and chemical stability. Microwave vacuum windows for modern high power sources and transmission lines operating at the megawatt power level require high quality diamond disks with a diameter of several centimeters and a thickness of a few millimeters. The microwave plasma-assisted CVD technique exploited today to produce such disks has low deposition rate, which limits the availability of large size diamond disk windows. High-electron-density plasma generated by the millimeter-wave power was suggested for enhanced-growth-rate CVD. In this paper a general description of the 30 GHz gyrotron-based facility is presented. The output radiation of the gyrotron is converted into four wave-beams. Free localized plasma in the shape of a disk with diameter much larger than the wavelength of the radiation is formed in the intersection area of the wave-beams. The results of investigation of the plasma parameters, as well as the first results of diamond film deposition are presented. The prospects for commercially producing vacuum window diamond disks for high power microwave devices at much lower costs and processing times than currently available are outlined.

  16. A design of experiments investigation of the effects of synthesis conditions on the quality of CVD graphene

    Science.gov (United States)

    Shanmugam, Ramakrishnan; Rangarajan, Murali; Devanathan, Sriram; Sathe, Vasant G.; Senthilkumar, R.; Kothurkar, Nikhil K.

    2016-12-01

    Control over quality of graphene and the number of layers is vital for various applications. This is the first methodical report which quantitatively relates the process conditions in the chemical vapor deposition (CVD) of graphene with crystallinity and number of graphene layers, using a design of experiments approach. This report investigates the effects of three vital synthesis parameters namely (i) carbon source (benzene, naphthalene and anthracene) (ii) synthesis temperature and (iii) mass flow rate of the carbon source, on the crystallinity and the number of layers of graphene, as inferred through micro-Raman analysis. These results give a preliminary indication of how the quality of graphene synthesized through CVD could be controlled. These results throw light on further experiments, simulations, and analysis needed to precisely determine how to control the synthesis of graphene.

  17. Cold-walled UHV/CVD batch reactor for the growth of Si1_x/Gex layers

    DEFF Research Database (Denmark)

    Thomsen, Erik Vilain; Christensen, Carsten; Andersen, C.R.;

    1997-01-01

    A novel cold-walled, lamp-heated, ultrahigh vacuum chemical vapor deposition (UHV/CVD) batch system for the growth of SiGe layers is presented. This system combines the batch capability of the standard UHV/CVD furnace with the temperature processing available in rapid thermal processing (Rm) equi...

  18. Simulation and experimental study of CVD process for low temperature nanocrystalline silicon carbide coating

    Energy Technology Data Exchange (ETDEWEB)

    Kaushal, Amit; Prakash, Jyoti, E-mail: jprakash@barc.gov.in; Dasgupta, Kinshuk; Chakravartty, Jayanta K.

    2016-07-15

    Highlights: • Parametric simulation was carried out for specially designed CVD reactor. • Effect of fluid velocity, heat flow and concentration were studied in CVD reactor. • Coating study carried out using low temperature and environmental safe CVD process. • Dense and uniform nanocrystalline SiC film was coated on zircaloy substrate. - Abstract: There is a huge requirement for development of a coating technique in nuclear industry, which is environmentally safe, economical and applicable to large scale components. In this view, simulation of gas-phase behavior in specially designed CVD reactor was carried out using computational tool, COMSOL. There were two important zones in CVD reactor first one is precursor vaporization zone and second one is coating zone. Optimized parameters for coating were derived from the simulation of gas phase dynamics in both zone of CVD reactor. The overall effect of fluid velocity, heat flow and concentration profile showed that Re = 54 is the optimum reaction condition for uniform coating in CVD system. In CVD coating experiments a synthesized halogen free, non-toxic and non-corrosive silicon carbide precursor was used. Uniform coating of SiC was obtained on zircaloy substrate at 900 °C using as synthesized organosilicon precursor. The X-ray diffraction and scanning electron microscopy analysis show that dense nano crystalline SiC film was deposited on zircaloy substrate.

  19. Methods of Boron-carbon Deposited Film Removal

    Science.gov (United States)

    Airapetov, A.; Terentiev, V.; Voituk, A.; Zakharov, A.

    Boron carbide was proposed as a material for in-situ renewable protecting coating for tungsten tiles of the ITER divertor. It is necessary to develop a method of gasification of boron-carbon film which deposits during B4C sputtering. In this paper the results of the first stage investigation of gasification methods of boron-carbon films are presented. Two gasification methods of films are investigated: interaction with the ozone-oxygen mixture and irradiation in plasma with the working gas composed of oxygen, ethanol, and, in some cases, helium. The gasification rate in the ozone-oxygen mixture at 250 °C for B/C films with different B/C ratio and carbon fiber composite (CFC), was measured. For B/C films the gasification rate decreased with increasing B/C ratio (from 45 nm/h at B/C=0.7 to 4 nm/h at B/C=2.1; for CFC - 15 μm/h). Films gasification rates were measured under ion irradiation from ethanol-oxygen-helium plasma at different temperatures, with different ion energies and different gas mixtures. The maximum obtained removal rate was near 230 nm/h in case of ethanol-oxygen plasma and at 150°C of the sample temperature.

  20. CVD-grown Fe2+:ZnSe polycrystals for laser applications

    Science.gov (United States)

    Firsov, K. N.; Gavrishchuk, E. M.; Ikonnikov, V. B.; Kazantsev, S. Yu; Kononov, I. G.; Rodin, S. A.; Savin, D. V.; Sirotkin, A. A.; Timofeeva, N. A.

    2017-05-01

    A technique for growing bulk zinc selenide polycrystals, doped with iron ions, by chemical vapor deposition (CVD), has been developed. It has been shown that iron is embedded in the crystal lattice of deposited zinc selenide in the optically active state of Fe2+. To improve the optical quality, the grown material was subjected to postgrowth hot isostatic pressing (HIP) treatment. It was experimentally demonstrated that the synthesised bulk crystals can be used as the active media of Fe2+:ZnSe lasers and as the passive Q-switches for three-micron lasers. The letter goes on to discuss the prospect of extending the proposed method to the synthesis of zinc sulphide doped with iron ions.

  1. Filmes de diamante CVD dopado com boro. Parte I . Histórico, produção e caracterização Boron-doped CVD diamond films. Part I. History, production and characterization

    Directory of Open Access Journals (Sweden)

    Rita de Cássia Mendes de Barros

    2005-03-01

    Full Text Available This review presents a brief account concerning the production, characterization and evolution of the knowledge in the area of diamond and boron-doped diamond films. The most important methods used for the growth of these films, such as chemical vapor deposition and high pressure/high temperature systems, as well as the several kinds of reactors which can be employed are reviewed. However, larger emphasis is given to the CVD method. Morphological, structural and electric properties of these films, as well as their role in the performance of voltammetric electrodes for electrochemistry and electroanalytical chemistry are also discussed.

  2. Dosimetric characterization of CVD diamonds irradiated with 62 MeV proton beams

    Energy Technology Data Exchange (ETDEWEB)

    Cirrone, G.A.P. [Laboratori Nazionali del Sud, INFN, Catania (Italy)]. E-mail: cirrone@lns.infn.it; Cuttone, G. [Laboratori Nazionali del Sud, INFN, Catania (Italy); Lo Nigro, S. [Laboratori Nazionali del Sud, INFN, Catania (Italy); Dipartimento di Fisica ed Astronomia, Universita di Catania (Italy); CSFNSM Centro Siciliano di Fisica Nucleare e Struttura della MAteria, Catania (Italy); Mongelli, V. [Laboratori Nazionali del Sud, INFN, Catania (Italy); Scuola di Specializzazione in Fisica Sanitaria, Universita di Catania (Italy); CSFNSM Centro Siciliano di Fisica Nucleare e Struttura della MAteria, Catania (Italy); Raffaele, L. [Laboratori Nazionali del Sud, INFN, Catania (Italy); Sabini, M.G. [Laboratori Nazionali del Sud, INFN, Catania (Italy); Azienda Ospedaliera Cannizzaro, Catania (Italy); Valastro, L. [Laboratori Nazionali del Sud, INFN, Catania (Italy); Scuola di Specializzazione in Fisica Sanitaria, Universita di Catania (Italy); Bucciolini, M. [Dipartimento di Fisiopatologia Clinica, Universita di Florence (Italy); Onori, S. [Istituto Superiore di Sanita, Rome (Italy)

    2005-10-21

    Diamond is potentially a very suitable material for use as on-line radiation dosimeter. Recent advances in the synthesis of polycrystalline diamond by chemical vapor deposition (CVD) techniques have produced material with electronic properties suitable for dosimetry applications. In this work the possibility to use a segmented commercial CVD detector in the dosimetry of proton beams has been investigated. The response as function of dose, dose rate, the priming and the rise time have been investigated thoroughly. This study shows the suitability of CVD diamond for dosimetry of clinical 62 MeV proton beams.

  3. High power RF window deposition apparatus, method, and device

    Energy Technology Data Exchange (ETDEWEB)

    Ives, Lawrence R.; Lucovsky, Gerald; Zeller, Daniel

    2017-07-04

    A process for forming a coating for an RF window which has improved secondary electron emission and reduced multipactor for high power RF waveguides is formed from a substrate with low loss tangent and desirable mechanical characteristics. The substrate has an RPAO deposition layer applied which oxygenates the surface of the substrate to remove carbon impurities, thereafter has an RPAN deposition layer applied to nitrogen activate the surface of the substrate, after which a TiN deposition layer is applied using Titanium tert-butoxide. The TiN deposition layer is capped with a final RPAN deposition layer of nitridation to reduce the bound oxygen in the TiN deposition layer. The resulting RF window has greatly improved titanium layer adhesion, reduced multipactor, and is able to withstand greater RF power levels than provided by the prior art.

  4. Radiation Hardness and Linearity Studies of CVD Diamonds

    CERN Document Server

    Behnke, T; Ghodbane, N; Imhof, A

    2003-01-01

    We report on the behavior of CVD diamonds under intense electromagnetic radiation and on the response of the detector to high density of deposited energy. Diamonds have been found to remain unaffected after doses of 10 MGy of MeV-range photons and the diamond response to energy depositions of up to 250 GeV/cm^3 has been found to be linear to better than 2 %. These observations make diamond an attractive detector material for a calorimeter in the very forward region of the detector proposed for TESLA.

  5. CVD of pure copper films from amidinate precursor

    OpenAIRE

    2009-01-01

    Copper(I) amidinate [Cu(i-Pr-Me-AMD)]2 was investigated to produce copper films in conventional low pressure chemical vapor deposition (CVD) using hydrogen as reducing gas-reagent. Copper films were deposited on steel, silicon, and SiO2/Si substrates in the temperature range 200–350°C at a total pressure of 1333 Pa. The growth rate on steel follows the surface reaction between atomic hydrogen and the entire precursor molecule up to 240°C. A significant increase of the growth rate at tempera...

  6. Uniform deposition of uranium hexafluoride (UF6): Standardized mass deposits and controlled isotopic ratios using a thermal fluorination method.

    Science.gov (United States)

    McNamara, Bruce K; O'Hara, Matthew J; Casella, Andrew M; Carter, Jennifer C; Addleman, R Shane; MacFarlan, Paul J

    2016-07-01

    We report a convenient method for the generation of volatile uranium hexafluoride (UF6) from solid uranium oxides and other U compounds, followed by uniform deposition of low levels of UF6 onto sampling coupons. Under laminar flow conditions, UF6 is shown to interact with surfaces within a fixed reactor geometry to a highly predictable degree. We demonstrate the preparation of U deposits that range between approximately 0.01 and 500ngcm(-2). The data suggest the method can be extended to creating depositions at the sub-picogramcm(-2) level. The isotopic composition of the deposits can be customized by selection of the U source materials and we demonstrate a layering technique whereby two U solids, each with a different isotopic composition, are employed to form successive layers of UF6 on a surface. The result is an ultra-thin deposit that bears an isotopic signature that is a composite of the two U sources. The reported deposition method has direct application to the development of unique analytical standards for nuclear safeguards and forensics. Further, the method allows access to very low atomic or molecular coverages of surfaces.

  7. The effect of alkaline doped catalysts on the CVD synthesis of carbon nanotubes

    DEFF Research Database (Denmark)

    Nemeth, Krisztian; Nemeth, Zoltan; Fejes, Dora;

    2011-01-01

    The aim of this work was to develop new doped catalysts for chemical vapour deposition (CVD) synthesis in order to increase the quantity and quality of carbon nanotubes (CNTs). Doping compounds such as CsBr, CsCl, KBr and KCl were used to reach higher carbon deposit and carbon yield. The amount o...

  8. CVD of solid oxides in porous substrates for ceramic membrane modification

    NARCIS (Netherlands)

    Lin, Y.S.; Burggraaf, A.J.

    1992-01-01

    The deposition of yttria-doped zirconia has been experimented systematically in various types of porous ceramic substrates by a modified chemical vapor deposition (CVD) process operating in an opposing reactant geometry using water vapor and corresponding metal chloride vapors as reactants. The effe

  9. Uniform deposition of uranium hexafluoride (UF6): Standardized mass deposits and controlled isotopic ratios using a thermal fluorination method

    Energy Technology Data Exchange (ETDEWEB)

    McNamara, Bruce K.; O’Hara, Matthew J.; Casella, Andrew M.; Carter, Jennifer C.; Addleman, R. Shane; MacFarlan, Paul J.

    2016-07-01

    Abstract: We report a convenient method for the generation of volatile uranium hexafluoride (UF6) from solid uranium oxides and other uranium compounds, followed by uniform deposition of low levels of UF6 onto sampling coupons. Under laminar flow conditions, UF6 is shown to interact with surfaces within the chamber to a highly predictable degree. We demonstrate the preparation of uranium deposits that range between ~0.01 and 470±34 ng∙cm-2. The data suggest the method can be extended to creating depositions at the sub-picogram∙cm-2 level. Additionally, the isotopic composition of the deposits can be customized by selection of the uranium source materials. We demonstrate a layering technique whereby two uranium solids, each with a different isotopic composition, are employed to form successive layers of UF6 on a surface. The result is an ultra-thin deposit of UF6 that bears an isotopic signature that is a composite of the two uranium sources. The reported deposition method has direct application to the development of unique analytical standards for nuclear safeguards and forensics.

  10. The evaluation of radiation damage parameter for CVD diamond

    Science.gov (United States)

    Grilj, V.; Skukan, N.; Jakšić, M.; Pomorski, M.; Kada, W.; Kamiya, T.; Ohshima, T.

    2016-04-01

    There are a few different phenomenological approaches that aim to track the dependence of signal height in irradiated solid state detectors on the fluence of damaging particles. However, none of them are capable to provide a unique radiation hardness parameter that would reflect solely the material capability to withstand high radiation environment. To extract such a parameter for chemical vapor deposited (CVD) diamond, two different diamond detectors were irradiated with proton beams in MeV energy range and subjected afterwards to ion beam induced charge (IBIC) analysis. The change in charge collection efficiency (CCE) due to defects produced was investigated in context of a theoretical model that was developed on the basis of the adjoint method for linearization of the continuity equations of electrons and holes. Detailed modeling of measured data resulted with the first known value of the kσ product for diamond, where k represents the number of charge carriers' traps created per one simulated primary lattice vacancy and σ represents the charge carriers' capture cross section. As discussed in the text, this product could be considered as a true radiation damage parameter.

  11. Contact resistance study of various metal electrodes with CVD graphene

    Science.gov (United States)

    Gahoi, Amit; Wagner, Stefan; Bablich, Andreas; Kataria, Satender; Passi, Vikram; Lemme, Max C.

    2016-11-01

    In this study, the contact resistance of various metals to chemical vapor deposited (CVD) monolayer graphene is investigated. Transfer length method (TLM) structures with varying channel widths and separation between contacts have been fabricated and electrically characterized in ambient air and vacuum condition. Electrical contacts are made with five metals: gold, nickel, nickel/gold, palladium and platinum/gold. The lowest value of 92 Ω μm is observed for the contact resistance between graphene and gold, extracted from back-gated devices at an applied back-gate bias of -40 V. Measurements carried out under vacuum show larger contact resistance values when compared with measurements carried out in ambient conditions. Post processing annealing at 450 °C for 1 h in argon-95%/hydrogen-5% atmosphere results in lowering the contact resistance value which is attributed to the enhancement of the adhesion between metal and graphene. The results presented in this work provide an overview for potential contact engineering for high performance graphene-based electronic devices.

  12. The evaluation of radiation damage parameter for CVD diamond

    Energy Technology Data Exchange (ETDEWEB)

    Grilj, V., E-mail: vgrilj@irb.hr [Division for Experimental Physics, Ruđer Bošković Institute, 10000 Zagreb (Croatia); Skukan, N.; Jakšić, M. [Division for Experimental Physics, Ruđer Bošković Institute, 10000 Zagreb (Croatia); Pomorski, M. [CEA-LIST, Diamond Sensors Laboratory, Gif-sur-Yvette F-91191 (France); Kada, W. [Division of Electronics and Informatics, Faculty of Science and Technology, Gunma University, Kiryu, Gunma 376-8515 (Japan); Kamiya, T.; Ohshima, T. [Japan Atomic Energy Agency (JAEA), Takasaki, Gunma 370-1292 (Japan)

    2016-04-01

    There are a few different phenomenological approaches that aim to track the dependence of signal height in irradiated solid state detectors on the fluence of damaging particles. However, none of them are capable to provide a unique radiation hardness parameter that would reflect solely the material capability to withstand high radiation environment. To extract such a parameter for chemical vapor deposited (CVD) diamond, two different diamond detectors were irradiated with proton beams in MeV energy range and subjected afterwards to ion beam induced charge (IBIC) analysis. The change in charge collection efficiency (CCE) due to defects produced was investigated in context of a theoretical model that was developed on the basis of the adjoint method for linearization of the continuity equations of electrons and holes. Detailed modeling of measured data resulted with the first known value of the kσ product for diamond, where k represents the number of charge carriers’ traps created per one simulated primary lattice vacancy and σ represents the charge carriers’ capture cross section. As discussed in the text, this product could be considered as a true radiation damage parameter.

  13. Method for depositing high-quality microcrystalline semiconductor materials

    Science.gov (United States)

    Guha, Subhendu; Yang, Chi C.; Yan, Baojie

    2011-03-08

    A process for the plasma deposition of a layer of a microcrystalline semiconductor material is carried out by energizing a process gas which includes a precursor of the semiconductor material and a diluent with electromagnetic energy so as to create a plasma therefrom. The plasma deposits a layer of the microcrystalline semiconductor material onto the substrate. The concentration of the diluent in the process gas is varied as a function of the thickness of the layer of microcrystalline semiconductor material which has been deposited. Also disclosed is the use of the process for the preparation of an N-I-P type photovoltaic device.

  14. Hot wire chemical vapor deposition: recent progress, present state of the art and competitive opportunities

    NARCIS (Netherlands)

    Schropp, R.E.I.

    2009-01-01

    Hot Wire CVD (also called Catalytic CVD or initiated CVD) is an elegant low pressure deposition technique for the deposition of functional films, both inorganic and organic, based on the decomposition of precursor sources at a heated metallic surface. The conformal deposition of thin films on rigid

  15. X-ray sensitivity measurements on CVD diamond film detectors

    Energy Technology Data Exchange (ETDEWEB)

    Foulon, F.; Pochet, T. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. d`Electronique et d`Instrumentation Nucleaire; Gheeraert, E. [Centre National de la Recherche Scientifique (CNRS), 38 - Grenoble (France)

    1993-12-31

    Microwave chemical vapor deposited (CVD) diamond films have been used to fabricate radiation detectors. The polycrystalline diamond films have a resistivity of 10{sup 12} ohm.cm and carrier mobility and lifetime of about 280 cm{sup 2}/V.s and 530 ps. The detector response to laser pulses (355, 532 and 1064 nm), X-ray flux (15-50 keV) and alpha particles ({sup 241}Am, 5.49 MeV) has been investigated. The response speed of the detector is in the 100 ps range. A sensitivity of about 3 x 10{sup -10} A/V.Gy.s was measured under 50 keV X-ray flux. The detector current response to X-ray flux is almost linear. It is also shown that CVD diamond detectors can be used for alpha particle counting. (authors). 9 figs., 25 refs.

  16. Optimization of process parameters in a large-area hot-wire CVD reactor for the deposition of amorphous silicon (a-Si:H) for solar cell application with highly uniform material quality

    Energy Technology Data Exchange (ETDEWEB)

    Pflueger, A.; Mukherjee, C.; Schroeder, B. [Department of Physics, Center of Materials Science, University of Kaiserslautern, P.O. Box 3049, D-67653 Kaiserslautern (Germany)

    2002-07-01

    Scale-up of a-Si:H-based thin film applications such as solar cells, entirely or partly prepared by hot-wire chemical vapor deposition (HWCVD), requires research on the deposition process in a large-area HWCVD system. The influence of gas supply and filament geometry on thickness uniformity has already been reported, but their influence on material quality is systematically studied for the first time. The optimization of deposition parameters for obtaining best material quality in our large-area HWCVD system resulted in an optimum filament temperature, T{sub fil}{approx}1600C, pressure, p=8mTorr and silane flow, F(SiH{sub 4})=100sccm, keeping the substrate temperature at T{sub S}=200C. A special gas supply (gas shower with tiny holes of uniform size) and a filament grid, consisting of six filaments with an interfilament distance, d{sub fil}=4cm were used. The optimum filament-to-substrate distance was found to be d{sub fil-S}=8.4cm. While studying the influence of different d{sub fil} and gas supply configurations on the material quality, the above-mentioned setup and parameters yield best results for both uniformity and material quality. With the setup mentioned, we could achieve device quality a-Si:H films with a thickness uniformity of {+-}2.5% on a circular area of 20cm in diameter. The material, grown at a deposition rate of r{sub d}{approx}4A/s, was characterized on nine positions of the 30cmx30cm substrate area, and revealed reasonable uniformity of the opto-electronic properties, e.g photosensitivity, {sigma}{sub Ph}/{sigma}{sub D}=(2.46{+-}0.7)x10{sup 5}, microstructure factor, R=0.17{+-}0.05, defect densities, N{sub d(PDS)}=(2.06{+-}0.6)x10{sup 17}cm{sup -3} and N{sub d(CPM)}=(2.05{+-}0.5)x10{sup 16}cm{sup -3} (film properties are given as mean values and standard deviations). Finally, we fabricated pin solar cells, with the i-layer deposited on small-area p-substrates distributed over an area of 20cmx20cm in this large-area deposition system, and

  17. The Effects of Two Thick Film Deposition Methods on Tin Dioxide Gas Sensor Performance

    OpenAIRE

    Bakrania, Smitesh D.; Margaret S. Wooldridge

    2009-01-01

    This work demonstrates the variability in performance between SnO2 thick film gas sensors prepared using two types of film deposition methods. SnO2 powders were deposited on sensor platforms with and without the use of binders. Three commonly utilized binder recipes were investigated, and a new binder-less deposition procedure was developed and characterized. The binder recipes yielded sensors with poor film uniformity and poor structural integrity, compared to the binder-less deposition meth...

  18. FABRICATION OF CNTS BY TOLUENE DECOMPOSITION IN A NEW REACTOR BASED ON AN ATMOSPHERIC PRESSURE PLASMA JET COUPLED TO A CVD SYSTEM

    Directory of Open Access Journals (Sweden)

    FELIPE RAMÍREZ-HERNÁNDEZ

    2017-03-01

    Full Text Available Here, we present a method to produce carbon nanotubes (CNTs based on the coupling between two conventional techniques used for the preparation of nanostructures: an arc-jet as a source of plasma and a chemical vapour deposition (CVD system. We call this system as an “atmospheric pressure plasma (APP-enhanced CVD” (APPE-CVD. This reactor was used to grow CNTs on non-flat aluminosilicate substrates by the decomposition of toluene (carbon source in the presence of ferrocene (as a catalyst. Both, CNTs and by-products of carbon were collected at three different temperatures (780, 820 and 860 °C in different regions of the APPE-CVD system. These samples were analysed by thermogravimetric analysis (TGA and DTG, scanning electron microscopy (SEM and Raman spectroscopy in order to determine the effect of APP on the thermal stability of the as-grown CNTs. It was found that the amount of metal catalyst in the synthesised CNTs is reduced by applying APP, being 820 °C the optimal temperature to produce CNTs with a high yield and carbon purity (95 wt. %. In contrast, when the synthesis temperature was fixed at 780 °C or 860 °C, amorphous carbon or CNTs with different structural defects, respectively, was formed through APEE-CVD reactor. We recommended the use of non-flat aluminosilicate particles as supports to increase CNT yield and facilitate the removal of deposits from the substrate surface. The approach that we implemented (to synthesise CNTs by using the APPE-CVD reactor may be useful to produce these nanostructures on a gram-scale for use in basic studies. The approach may also be scaled up for mass production.

  19. Diagramas de fase CVD para la preparación de películas de iridio

    Directory of Open Access Journals (Sweden)

    Hernández-Pérez, M. A.

    2002-02-01

    Full Text Available Chemical vapor deposition (CVD phase diagrams for the preparation of iridium films were calculated using Gibbs free energy minimization method. Iridium acetylacetonate (Ir(acac3 was used as the precursor compound. Two gaseous mixtures were analyzed: Ir(acac3-O2-Ar and Ir(acac3-Ar. The deposition temperatures were explored from 300 to 800 °C, total pressures from 13.3 to 13.332 Pa and partial pressures of Ir(acac3 gas and O2 gas from 0.001 to 1.000 Pa. The Ir-CVD diagrams predicted that without Oj gas in the gaseous mixture, the solid films consist of two solid phases: Ir+C. In contrast, with addition of O2 to the gaseous mixture, the Ir-CVD diagrams revealed different domains of condensed phases which include IrO2, IrO2+Ir, Ir and Ir+C. These diagrams allow one to establish the total pressures and temperatures required to obtain a given film composition. The results predicted by the Ir-CVD diagrams are in good agreement with those experimentally obtained.

    Se calcularon los diagramas de fase CVD (Chemical Vapor Deposition para la preparación de películas de iridio empleando el método de minimización de la energía libre de Gibbs. Como precursor se utilizó acetilacetonato de iridio (Ir(acac3. Se analizaron las mezclas gaseosas Ir(acac3-O2Ar e Ir(acac3-Ar. Las temperaturas de depósito se exploraron desde 300 hasta 800 °C, las presiones totales de 13,3 a 13.332 Pa y las presiones parciales de los gases Ir(acac3 y O2 desde 0,001 hasta 1.000 Pa. Los diagramas Ir-CVD predicen que sin O2 en la mezcla gaseosa, las películas constan de las fases sólidas Ir+C. En contraste, con adición de O2 los diagramas Ir-CVD revelan diferentes dominios de fases sólidas que incluyen IrO2, IrO2+Ir, Ir e Ir+C. Estos diagramas permiten establecer

  20. Simple Chemical Vapor Deposition Experiment

    Science.gov (United States)

    Pedersen, Henrik

    2014-01-01

    Chemical vapor deposition (CVD) is a process commonly used for the synthesis of thin films for several important technological applications, for example, microelectronics, hard coatings, and smart windows. Unfortunately, the complexity and prohibitive cost of CVD equipment makes it seldom available for undergraduate chemistry students. Here, a…

  1. Analysis of Electrospraying as an On-demand Deposition Method

    NARCIS (Netherlands)

    Stachewicz , U.

    2010-01-01

    The goal of this thesis was to investigate the stability regime for electrospraying events. First of all, we wanted to use electrospraying as an on-demand volume deposition technology. For this purpose, a well controlled and precise liquid ejection was obtained. Instead of generating a continuous sp

  2. Freestanding single crystal chemical vapor deposited diamond films produced using a lift-off method: Response to {alpha}-particles from {sup 241}Am and crystallinity

    Energy Technology Data Exchange (ETDEWEB)

    Tsubouchi, Nobuteru, E-mail: nobu-tsubouchi@aist.go.jp [Diamond Research Laboratory, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan); Mokuno, Y. [Diamond Research Laboratory, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan); Kakimoto, A.; Fujita, F.; Kaneko, J.H. [Graduate School of Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Yamada, H.; Chayahara, A.; Shikata, S. [Diamond Research Laboratory, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan)

    2012-09-01

    Thick ({approx}100 {mu}m) undoped diamond films were grown homoepitaxially on single crystal (SC) diamond substrates by microwave plasma chemical vapor deposition (CVD). To form a freestanding SC diamond film (plate), the substrate was pre-ion-implanted with high-energy ion beams before the film growth, and after the thick-film deposition, the substrate was eliminated using a lift-off method, resulting in fabrication of a SC CVD diamond plate. Two samples were prepared; sample 1 was grown on a (0 0 1) oriented, nitrogen doped CVD SC diamond at {approx}900 Degree-Sign C with the input microwave power of 1.7 kW, while sample 2 was grown on a (0 0 1) oriented, high-pressure high-temperature synthesized type-Ib SC diamond at {approx}900 Degree-Sign C with the input microwave power of 1.25 kW. The formed SC plates have high optical transparencies, indicating no remarkable optical absorptions seen in the wavelength from ultraviolet to near infrared. The photoluminescence (PL) spectra of both samples show strong free exciton FE peaks, while in sample 2 relatively strong optical emissions corresponding to nitrogen related centers were observed in the visible region. After the metal electrodes were formed on both faces of the SC diamond plate to fabricate a sandwich-type diamond particle detector, the energy spectra of 5.486 MeV {alpha}-particles from {sup 241}Am were measured. The charge collection efficiencies (CCEs) of sample 1 were CCE = 98% for a hole transport and CCE = 89% for an electron transport, respectively, while CCEs of sample 2 were CCE = 80% for a hole transport and CCE = 78% for an electron transport, respectively. These results indicate that both holes and electrons in sample 2 were trapped much more than those in sample 1. Possible candidates of carrier capture centers are nitrogen and/or nitrogen-vacancy centers observed in PL, nonradiative defect (complex) centers, extended defects such as threading dislocations observed in micrographs taken with

  3. From Nanowires to Nanopores: A Versatile Method for Electroless Deposition of Nanostructures on Micropatterned Organic Substrates.

    Science.gov (United States)

    Ellsworth, Ashley A; Walker, Amy V

    2016-03-22

    We demonstrate a fast, flexible, parallel, and highly controllable method by which to synthesize a variety of nanoscale and mesoscale structures. This method addresses one of the most significant challenges in nanoscience: the in situ parallel placement and synthesis of nano-objects over the mesoscale. The method is based on electroless nanowire deposition on micropatterned substrates (ENDOM). In ENDOM nanostructures are produced at the boundary between two unlike materials if two conditions are met: (a) deposition is kinetically preferred on one of the materials while (b) transport of reactants is favored on the other. In this study, copper structures were deposited on patterned -OH/-CH3-terminated alkanethiolate self-assembled monolayers (SAMs) by exploiting the different reaction rates of electroless deposition on these using the reducing agent dimethylamine borane (DMAB). We demonstrate production of nanowires (width < 100 nm), mesowires (100 nm < width < ∼3000 nm), nanorings, nanopores, and nanochannels. We show that a variety of experimental conditions can be employed, making this method compatible with many substrates. We have also studied the nucleation and growth kinetics of the ENDOM process. The width of the deposit grows exponentially with deposition time and can be modeled using classical nucleation theory. Although the deposit width increases, the height and grain size of the copper deposit is constant (to within experimental uncertainty) with deposition time. These observations indicate that the minimum deposit width is controlled by the nanoparticle dimensions and so can be controlled using the reaction conditions.

  4. Chemical vapor deposition of mullite coatings

    Science.gov (United States)

    Sarin, Vinod; Mulpuri, Rao

    1998-01-01

    This invention is directed to the creation of crystalline mullite coatings having uniform microstructure by chemical vapor deposition (CVD). The process comprises the steps of establishing a flow of reactants which will yield mullite in a CVD reactor, and depositing a crystalline coating from the reactant flow. The process will yield crystalline coatings which are dense and of uniform thickness.

  5. Origin, state of the art and some prospects of the diamond CVD

    CERN Document Server

    Spitsyn, B V; Alexenko, A E

    2000-01-01

    A short review on the diamond CVD origin, together with its state of the art and some prospects was given. New hybrid methods of the diamond CVD permit to gain 1.2 to 6 times of growth rate in comparison with ordinary diamond CVD's. Recent results on n-type diamond film synthesis through phosphorus doping in the course of the CVD process are briefly discussed. In comparison with high-pressure diamond synthesis, the CVD processes open new facets of the diamond as ultimate crystal for science and technology evolution. It was stressed that, mainly on the basis of new CVDs of diamond, the properties of natural diamond are not only reproduced, but can be surpassed. As examples, mechanical (fracture resistance), physical (thermal conductivity), and chemical (oxidation stability) properties are mentioned. Some present issues in the field are considered.

  6. Liquid precursor for deposition of indium selenide and method of preparing the same

    Energy Technology Data Exchange (ETDEWEB)

    Curtis, Calvin J.; Miedaner, Alexander; van Hest, Marinus Franciscus Antonius Maria; Ginley, David S.; Hersh, Peter A.; Eldada, Louay; Stanbery, Billy J.

    2015-09-22

    Liquid precursors containing indium and selenium suitable for deposition on a substrate to form thin films suitable for semiconductor applications are disclosed. Methods of preparing such liquid precursors and method of depositing a liquid precursor on a substrate are also disclosed.

  7. Method of porous diamond deposition on porous silicon

    Science.gov (United States)

    Baranauskas, Vitor; Peterlevitz, Alfredo C.; Chang, Dahge C.; Durrant, Steven F.

    2001-12-01

    In this paper, we discuss the experimental results of the fabrication of porous diamond/porous silicon and porous diamond structures by chemical vapor deposition of diamond over a skeleton of porous silicon, replicating the porous surface geometry around the Si pores and also creating new porous diamond structures. Scanning electron microscopy (SEM) revealed that the diamond nuclei are deposited on the top of the porous silicon skeleton, forming isolated grains in the first nucleation stages, and then growing like the usual structure of most ceramic materials, making a self-sustained porous diamond structure. Raman spectroscopy revealed that the diamond films are of good quality, close to that of diamond films grown on crystalline silicon.

  8. CVD diamond resistor as heater and temperature sensor

    Energy Technology Data Exchange (ETDEWEB)

    Yang, G.S.; Aslam, M. [Michigan State Univ., East Lansing, MI (United States)

    1995-12-31

    Heat generation and temperature control, essential for most heater applications, require different components in a conventional system. We achieve the heat generation and temperature measurement simultaneously by using a single diamond resistor. Chemical vapor deposited (CVD) p-type diamond resistors with different dimensions were fabricated on polycrystalline diamond or oxidized Si substrates using diamond film technology compatible with integrated circuit (IC) processing. The temperature response of the resistors was characterized in the temperature range of 25 - 500{degrees}C. Power densities in access of 600 watt/in{sup 2} were achieved.

  9. Development of CVD Mullite Coatings for SiC Fibers

    Energy Technology Data Exchange (ETDEWEB)

    Sarin, V.K.; Varadarajan, S.

    2000-03-15

    A process for depositing CVD mullite coatings on SiC fibers for enhanced oxidation and corrosion, and/or act as an interfacial protective barrier has been developed. Process optimization via systematic investigation of system parameters yielded uniform crystalline mullite coatings on SiC fibers. Structural characterization has allowed for tailoring of coating structure and therefore properties. High temperature oxidation/corrosion testing of the optimized coatings has shown that the coatings remain adherent and protective for extended periods. However, preliminary tests of coated fibers showed considerable degradation in tensile strength.

  10. CVD diamond sensor for UV-photon detection

    CERN Document Server

    Periale, L; Gervino, G; Lamarina, A M; Palmisano, C; Periale, R; Picchi, P

    2012-01-01

    A new generation of UV photosensors, based on single crystal Chemical Vapour Deposition (CVD) diamonds to work optically coupled with large volume two-phase liquid-Ar (LAr) or liquid-Xe (LXe) detectors nowadays under design for the next generation of WIMPs experiments, is under development. Preliminary tests and first calibrations show these devices can have better performance than the existing UV sensitive detectors (higher photosensitivity and better signal-to-noise ratio). I-V characteristics, dark current measurements, linearity response to X-ray irradiation, and alpha-particle energy resolution are reported and discussed. (C) 2011 Elsevier B.V. All rights reserved.

  11. Computation of flow and thermal fields in a model CVD reactor

    Indian Academy of Sciences (India)

    Vishwadeep Saxena; K Muralidhar; V Eswaran

    2002-12-01

    Mixing of coaxial jets within a tube in the presence of blockage has been numerically studied. This configuration is encountered during the modelling of flow and heat transfer in CVD (chemical vapour deposition) reactors. For the conditions prevailing in the reactor, the Reynolds numbers are low and flow can be taken to be laminar and incompressible. The unsteady forms of the governing equations have been solved by a finite volume method that can treat complex three-dimensional geometries. The algorithm is a two-step procedure, wherein the first step predicts the velocity field using an assumed pressure field. The second step corrects the fields using a Poisson equation to obtain the pressure corrections. Advection terms have been treated by a hybrid upwind-central difference technique. The computer code developed is fully three-dimensional, though most computations of the present study have been carried out for two-dimensional geometry. Results have been obtained in the form of velocity vector plots, wall shear stress variation on the block and the tube wall, isotherms and temperature profiles. The flow and heat transfer characteristics of jet mixing have been explored in terms of the Reynolds number, the jet velocity ratio, the axial position of the block, and the blockage ratio. The results obtained show that a proper combination of the process parameters can lead to an improved performance of the CVD reactor.

  12. Large scale integration of CVD-graphene based NEMS with narrow distribution of resonance parameters

    Science.gov (United States)

    Arjmandi-Tash, Hadi; Allain, Adrien; (Vitto Han, Zheng; Bouchiat, Vincent

    2017-06-01

    We present a novel method for the fabrication of the arrays of suspended micron-sized membranes, based on monolayer pulsed-CVD graphene. Such devices are the source of an efficient integration of graphene nano-electro-mechanical resonators, compatible with production at the wafer scale using standard photolithography and processing tools. As the graphene surface is continuously protected by the same polymer layer during the whole process, suspended graphene membranes are clean and free of imperfections such as deposits, wrinkles and tears. Batch fabrication of 100 μm-long multi-connected suspended ribbons is presented. At room temperature, mechanical resonance of electrostatically-actuated devices show narrow distribution of their characteristic parameters with high quality factor and low effective mass and resonance frequencies, as expected for low stress and adsorbate-free membranes. Upon cooling, a sharp increase of both resonant frequency and quality factor is observed, enabling to extract the thermal expansion coefficient of CVD graphene. Comparison with state-of-the-art graphene NEMS is presented.

  13. Facet-dependent study of efficient growth of graphene on copper by ethanol-CVD

    Indian Academy of Sciences (India)

    Anil Kumar Singh; Anjan Kumar Gupta

    2015-12-01

    The growth of graphene by chemical vapour deposition (CVD) on copper is the most promising scalable method for high-quality graphene. The use of ethanol, an economic and safe precursor, for the fast growth of graphene on copper by a home-built CVD set-up was analysed. Full coverage of uniform single-layer graphene with high crystalline quality was found on $\\langle100\\rangle$ textured Cu foils in just 30 s. The nucleation density of graphene islands was found to be independent of facets but the island shape showed facet dependence. Diamond-like islands were observed on Cu(100) facets while random shaped islands were seen on other facets. The last observation is discussed in terms of a competition between graphene-island growth and its relaxation rate on different facets. On Cu(100) slower island growth as compared to its relaxation leads to equilibrium shapes as opposed to other facets. Further, an observed evolution in graphene contrast in electron micrographs with time on different facets was discussed in terms of oxygen diffusion between graphene and Cu.

  14. Effect of a Balanced Concentration of Hydrogen on Graphene CVD Growth

    Directory of Open Access Journals (Sweden)

    S. Chaitoglou

    2016-01-01

    Full Text Available The extraordinary properties of graphene make it one of the most interesting materials for future applications. Chemical vapor deposition (CVD is the synthetic method that permits obtaining large areas of monolayer graphene. To achieve this, it is important to find the appropriate conditions for each experimental system. In our CVD reactor working at low pressure, important factors appear to be the pretreatment of the copper substrate, considering both its cleaning and its annealing before the growing process. The carbon precursor/hydrogen flow ratio and its modification during the growth are significant in order to obtain large area graphene crystals with few defects. In this work, we have focused on the study of the methane and the hydrogen flows to control the production of single layer graphene (SLG and its growth time. In particular, we observe that hydrogen concentration increases during a usual growing process (keeping stable the methane/hydrogen flow ratio resulting in etched domains. In order to balance this increase, a modification of the hydrogen flow results in the growth of smooth hexagonal SLG domains. This is a result of the etching effect that hydrogen performs on the growing graphene. It is essential, therefore, to study the moderated presence of hydrogen.

  15. Non-vacuum deposition methods for thin film solar cell: Review

    Science.gov (United States)

    Yang, Ruisheng; Mazalan, Elham; Chaudhary, Kashif Tufail; Haider, Zuhaib; Ali, Jalil

    2017-03-01

    Solar power is a promising abundant, pollution free, inexhaustible and clean source of energy. Development of cost-effective solar system with high conversion efficiency is the key challenge in field of solar panel manufacturing industry. Different non-vacuum deposition methods have been developed to reduce the cost of solar panel system along with high conversion efficiency. In this paper, a review is presented with major focus on three non-vacuum deposition methods, as spin coating, dip coating and spray coating. Each mentioned deposition technique is discussed in details along with role of different deposition parameters on the characteristics of grown solar thin films.

  16. Sand deposit-detecting method and its application in model test of sand flow

    Institute of Scientific and Technical Information of China (English)

    黎伟; 房营光; 莫海鸿; 谷任国; 陈俊生

    2013-01-01

    Against the background of the sand-flow foundation treatment engineering of Guangzhou Zhoutouzui variable cross-section immersed tunnel, a kind of sand deposit-detecting method was devised on the basis of full-scale model test of sand-flow method. The real-time data of sand-deposit height and radius were obtained by the self-developed sand-deposit detectors. The test results show that the detecting method is simple and has high precision. In the use of sand-flow method, the sand-carrying capability of fluid is limited, and sand particles are all transported to the sand-deposit periphery through crater, gap and chutes after the sand deposit formed. The diffusion range of the particles outside the sand-deposit does not exceed 2.0 m. Severe sorting of sand particles is not observed because of the unique oblique-layered depositing process. The temporal and spatial distributions of gap and chutes directly affect the sand-deposit expansion, and the expansion trend of the average sand-deposit radius accords with quadratic time-history curve.

  17. Evaluation of methods for characterizations of deposits; Utvaerdering av metoder foer avlagringsmaetningar

    Energy Technology Data Exchange (ETDEWEB)

    Hoegberg, J.; Bjoerkman, P. [Vattenfall Utveckling AB, Aelvkarleby (Sweden)

    2001-11-01

    In boilers there are problems with deposits on parts exposed to the flue gas, in particular on heat exchanging parts and to an increasing extent with the changeover to the use of biofuels and wood waste fuels. In order to solve the problems deposits are examined by using a deposit probe and taking deposit samples from the interior of the boiler. In this report an evaluation of methods of analysis is performed based on experiences in both literature and laboratory work. The evaluation forms the basis of an instruction for deposit measurements in 'Vaermeforsks Maethandbok'. The procedure for use of deposit probes is treated as well as the importance of careful and well planned sample preparation before analysis. In the literature a large number of methods used for analysis of deposits from flue ashes and similar applications are found. The methods include chemical analyses of solids and liquids, analysis of crystal structures, thermal properties and the solid mechanics of the materials. Several methods, for example SEM-EDX, XRF, ICP, IC and methods for determining the mechanical and thermal properties are suited for a survey examination of a deposit, while more specialised methods with higher resolution can add information but require a clear framing of a question and in practice are suited for only separate samples. Examples from the latter category are AES, ESCA and TOF-SIMS.

  18. HV/CVD Grown Relaxed SiGe Buffer Layers for SiGe HMOSFETs

    Institute of Scientific and Technical Information of China (English)

    黄文韬; 罗广礼; 史进; 邓宁; 陈培毅; 钱佩信

    2003-01-01

    High-vacuum/chemical-vapor deposition (HV/CVD) system was used to grow relaxed SiGe buffer layers on Si substrates. Several methods were then used to analyze the quality of the SiGe films. X-ray diffraction and Raman spectroscopy showed that the upper layer was almost fully relaxed. Second ion mass spectroscopy showed that the Ge compositions were step-graded. Transmission electron microscopy showed that the misfit dislocations were restrained to the graded SiGe layers. Tests of the electrical properties of tensile-strained Si on relaxed SiGe buffer layers showed that their transconductances were higher than that of Si devices. These results verify the high quality of the relaxed SiGe buffer layer. The calculated critical layer thicknesses of the graded Si1-xGex layer on Si substrate and a Si layer on the relaxed SiGe buffer layer agree well with experimental results.

  19. Fracture Characteristics of Monolayer CVD-Graphene

    Science.gov (United States)

    Hwangbo, Yun; Lee, Choong-Kwang; Kim, Sang-Min; Kim, Jae-Hyun; Kim, Kwang-Seop; Jang, Bongkyun; Lee, Hak-Joo; Lee, Seoung-Ki; Kim, Seong-Su; Ahn, Jong-Hyun; Lee, Seung-Mo

    2014-03-01

    We have observed and analyzed the fracture characteristics of the monolayer CVD-graphene using pressure bulge testing setup. The monolayer CVD-graphene has appeared to undergo environmentally assisted subcritical crack growth in room condition, i.e. stress corrosion cracking arising from the adsorption of water vapor on the graphene and the subsequent chemical reactions. The crack propagation in graphene has appeared to be able to be reasonably tamed by adjusting applied humidity and stress. The fracture toughness, describing the ability of a material containing inherent flaws to resist catastrophic failure, of the CVD-graphene has turned out to be exceptionally high, as compared to other carbon based 3D materials. These results imply that the CVD-graphene could be an ideal candidate as a structural material notwithstanding environmental susceptibility. In addition, the measurements reported here suggest that specific non-continuum fracture behaviors occurring in 2D monoatomic structures can be macroscopically well visualized and characterized.

  20. Non-classical crystallization of thin films and nanostructures in CVD and PVD processes

    CERN Document Server

    Hwang, Nong Moon

    2016-01-01

    This book provides a comprehensive introduction to a recently-developed approach to the growth mechanism of thin films and nanostructures via chemical vapour deposition (CVD). Starting from the underlying principles of the low pressure synthesis of diamond films, it is shown that diamond growth occurs not by individual atoms but by charged nanoparticles. This newly-discovered growth mechanism turns out to be general to many CVD and some physical vapor deposition (PVD) processes. This non-classical crystallization is a new paradigm of crystal growth, with active research taking place on growth in solution, especially in biomineralization processes. Established understanding of the growth of thin films and nanostructures is based around processes involving individual atoms or molecules. According to the author’s research over the last two decades, however, the generation of charged gas phase nuclei is shown to be the rule rather than the exception in the CVD process, and charged gas phase nuclei are actively ...

  1. Deposition uniformity inspection in IC wafer surface

    Science.gov (United States)

    Li, W. C.; Lin, Y. T.; Jeng, J. J.; Chang, C. L.

    2014-03-01

    This paper focuses on the task of automatic visual inspection of color uniformity on the surface of integrated circuits (IC) wafers arising from the layering process. The oxide thickness uniformity within a given wafer with a desired target thickness is of great importance for modern semiconductor circuits with small oxide thickness. The non-uniform chemical vapor deposition (CVD) on a wafer surface will proceed to fail testing in Wafer Acceptance Test (WAT). Early detection of non-uniform deposition in a wafer surface can reduce material waste and improve production yields. The fastest and most low-priced inspection method is a machine vision-based inspection system. In this paper, the proposed visual inspection system is based on the color representations which were reflected from wafer surface. The regions of non-uniform deposition present different colors from the uniform background in a wafer surface. The proposed inspection technique first learns the color data via color space transformation from uniform deposition of normal wafer surfaces. The individual small region statistical comparison scheme then proceeds to the testing wafers. Experimental results show that the proposed method can effectively detect the non-uniform deposition regions on the wafer surface. The inspection time of the deposited wafers is quite compatible with the atmospheric pressure CVD time.

  2. Fracture Characteristics of Monolayer CVD-Graphene

    OpenAIRE

    Hwangbo, Yun; Lee, Choong-Kwang; Kim, Sang-Min; Kim, Jae-Hyun; Kim, Kwang-Seop; Jang, Bongkyun; Lee, Hak-Joo; Lee, Seoung-Ki; Kim, Seong-Su; Ahn, Jong-Hyun; Lee, Seung-Mo

    2014-01-01

    We have observed and analyzed the fracture characteristics of the monolayer CVD-graphene using pressure bulge testing setup. The monolayer CVD-graphene has appeared to undergo environmentally assisted subcritical crack growth in room condition, i.e. stress corrosion cracking arising from the adsorption of water vapor on the graphene and the subsequent chemical reactions. The crack propagation in graphene has appeared to be able to be reasonably tamed by adjusting applied humidity and stress. ...

  3. CVD and obesity in transitional Syria: a perspective from the Middle East

    Directory of Open Access Journals (Sweden)

    Baaj MK

    2012-03-01

    Full Text Available Hani Barakat1, Hanniya Barakat1, Mohamad K Baaj21Kalamoon Private University Medical School, Deir Attieh, Syria; 2Aleppo University Medical School, Aleppo, SyriaPurpose: Syria is caught in the middle of a disruptive nutritional transition. Its healthcare system is distracted by challenges and successes in other areas while neglecting to address the onslaught of Syria's cardiovascular disease (CVD epidemic. Despite the official viewpoint touting improvement in health indicators, current trends jeopardize population health, and several surveys in the Syrian population signal the epidemic spreading far and wide. The goal is to counteract the indifference towards obesity as a threat to Syrian's health, as the country is slowly becoming a leader in CVD mortality globally.Methods: PubMed, World Health Organization, and official government websites were searched for primary surveys in Syria related to CVD morbidity, mortality, and risk factors. Inclusion criteria ensured that results maximized relevance while producing comparable studies. Statistical analysis was applied to detect the most common risk factor and significant differences in risk factor prevalence and CVD rates.Results: Obesity remained the prevailing CVD risk factor except in older Syrian men, where smoking and hypertension were more common. CVD mortality was more common in males due to coronary disease, while stroke dominated female mortality. The young workforce is especially impacted, with 50% of CVD mortality occurring before age 65 years and an 81% prevalence of obesity in women over 45 years.Conclusion: Syria can overcome its slow response to the CVD epidemic and curb further deterioration by reducing obesity and, thus, inheritance and clustering of risk factors. This can be achieved via multilayered awareness and intensive parental and familial involvement. Extinguishing the CVD epidemic is readily achievable as demonstrated in other countries.Keywords: Syria, CVD, obesity, risk

  4. Urchin-like artificial gallium oxide nanowires grown by a novel MOCVD/CVD-based route for random laser application

    Energy Technology Data Exchange (ETDEWEB)

    Melo, Ronaldo P. de [Programa de Pós-Graduação em Ciências de Materiais, Universidade Federal de Pernambuco, Recife (Brazil); Colégio Militar do Recife, Exército Brasileiro, Recife PE 50730-120 (Brazil); Oliveira, Nathalia Talita C. [Programa de Pós-Graduação em Ciências de Materiais, Universidade Federal de Pernambuco, Recife (Brazil); Dominguez, Christian Tolentino; Gomes, Anderson S. L.; Araújo, Cid B. de [Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife (Brazil); Falcão, Eduardo H. L.; Alves, Severino; Luz, Leonis L. da [Departamento de Química Fundamental, Universidade Federal de Pernambuco, 50670-901 Recife (Brazil); Chassagnon, Remi [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-Université de Bourgogne, 9 Av. A. Savary, BP 47870, 21078 Dijon Cedex (France); Sacilotti, Marco [Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife (Brazil); Nanoform Group, Laboratoire Interdisciplinaire Carnot de Bourgogne, Université de Bourgogne, Dijon (France)

    2016-04-28

    A novel procedure based on a two-step method was developed to obtain β-Ga{sub 2}O{sub 3} nanowires by the chemical vapor deposition (CVD) method. The first step consists in the gallium micro-spheres growth inside a metal-organic chemical vapor deposition environment, using an organometallic precursor. Nanoscale spheres covering the microspheres were obtained. The second step involves the CVD oxidization of the gallium micro-spheres, which allow the formation of β-Ga{sub 2}O{sub 3} nanowires on the micro-sphere surface, with the final result being a nanostructure mimicking nature's sea urchin morphology. The grown nanomaterial is characterized by several techniques, including X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray, transmission electron microscopy, and photoluminescence. A discussion about the growth mechanism and the optical properties of the β-Ga{sub 2}O{sub 3} material is presented considering its unknown true bandgap value (extending from 4.4 to 5.68 eV). As an application, the scattering properties of the nanomaterial are exploited to demonstrate random laser emission (around 570 nm) when it is permeated with a laser dye liquid solution.

  5. Deposition and Tribological Properties of Sulfur-Doped DLC Films Deposited by PBII Method

    Directory of Open Access Journals (Sweden)

    Nutthanun Moolsradoo

    2010-01-01

    Full Text Available Sulfur-doped diamond-like carbon films (S-DLC fabricated from C2H2 and SF6 mixtures were used to study the effects of sulfur content and negative pulse bias voltage on the deposition and tribological properties of films prepared by plasma-based ion implantation (PBII. The structure and relative concentration of the films were analyzed by Raman spectroscopy and Auger electron spectroscopy. Hardness and elastic modulus of films were measured by nanoindentation hardness testing. Tribological characteristics of films were performed using a ball-on-disk friction tester. The results indicate that with the increasing sulfur content, the hardness and elastic modulus decrease. Additionally, by changing the negative pulse bias voltage from 0 kV to −5 kV, the hardness and elastic modulus increase, while the friction coefficient and specific wear rate tends to decrease. Moreover, at a negative pulse bias voltage of −5 kV and flow-rate ratio of 1 : 2, there is considerable improvement in friction coefficient of 0.05 under ambient air is due to the formation of a transfer films on the interface. The decrease in the friction coefficient of films doped with 4.9 at.% sulfur is greater under high vacuum (0.03 than under ambient air (>0.1.

  6. Recent Results from Beam Tests of 3D and Pad pCVD Diamond Detectors

    CERN Document Server

    Wallny, Rainer

    2017-01-01

    Results from prototypes of a detector using chemical vapor deposited (CVD) diamond with embedded resistive electrodes in the bulk forming a 3D diamond device are presented. A detector system consisting of 3D devices based on poly-crystalline CVD (pCVD) diamond was connected to a multi-channel readout and successfully tested in a 120 GeV/c proton beam at CERN proving for the first time the feasibility of the 3D detector concept in pCVD for particle tracking applications. We also present beam test results on the dependence of signal size on incident particle rate in charged particle detectors based on poly-crystalline CVD diamond. The detectors were tested in a 260 MeV/c pion beam over a range of particle fluxes from 2 kHz/cm2 to 10 MHz/cm2 . The pulse height of the sensors was measured with pad readout electronics at a peaking time of 7 ns. Our data from the 2015 beam tests at PSI indicate that the pulse height of poly-crystalline CVD diamond sensor irradiated to 5×1014 neq/cm2 is independent of particle flux...

  7. Laser-guided direct writing: a novel method to deposit biomolecules for biosensors arrays.

    Science.gov (United States)

    Xu, Juntao; Grant, Sheila A; Pastel, Robert L

    2003-01-01

    In this paper, we present a potential biomolecular patterning method, laser-guided direct writing guidance (LGDW), which may be utilized to deposit organic and bioactive particles for biosensor arrays. The instrumentation and operation of the LGDW system is introduced and the system settings used to achieve deposition are reported. The biomolecule, avidin, was deposited onto a substrate using LGDW to evaluate the possible damage from the laser on the biomolecules. The functionality of avidin after laser-based guidance was examined by exposing the deposited avidin molecules to its ligand, biotin. The results show some avidin retained its affinity to biotin after LGDW demonstrating little damage to the biomolecules.

  8. Deposition of YBCO Thin Film by Aerosol Assisted Spray Pyrolysis Method using Nitrate Precursors

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Byeong Joo; Hong, Seok Kwan; Lee, Jong Beom; Lee, Hee Gyoun; Hong, Gye Won [Korea Polytechnic University, Siheung (Korea, Republic of); Kim, Jae Geun [ISEM, University of Wollongong, Wollongong (Korea, Republic of)

    2010-10-15

    Y123 films have been deposited on (100) single-crystal and IBAD substrates by spray pyrolysis method using nitrate precursors. Ultrasonic atomization was adopted to decrease the droplet size, spraying angle and its moving velocity toward substrate for introducing the preheating tube furnace in appropriate location. A small preheating tube furnace was installed between spraying nozzle and substrate for fast drying and enhanced decomposition of precursors. C-axis oriented films were obtained on both LAO and IBAD substrates at deposition temperature of around and working pressures of 10-15 torr. Thick c-axis epitaxial film with the thickness of was obtained on LAO single-crystal by 10 min deposition. But the XRD results of the film deposited on IBAD template at same deposition condition showed that the buffer layers of the IBAD metal substrate was affected by long residence of metal substrate at high temperature for YBCO deposition.

  9. Atomic scale KMC simulation of {100} oriented CVD diamond film growth under low substrate temperature-Part II Simulation of CVD diamond film growth in C-H system and in Cl-containing systems

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The growth of {100}-oriented CVD diamond film under two modifications of J-B-H model at low substrate temperatures was simulated by using a revised KMC method at atomic scale. The results were compared both in Cl-containing systems and in C-H system as follows: (1) Substrate temperature can produce an important effect both on film deposition rate and on surface roughness; (2) Aomic Cl takes an active role for the growth of diamond film at low temperatures; (3) {100}-oriented diamond film cannot deposit under single carbon insertion mechanism, which disagrees with the predictions before; (4) The explanation of the exact role of atomic Cl is not provided in the simulation results.

  10. Optical and structural properties of polycrystalline CVD diamond films grown on fused silica optical fibres pre-treated by high-power sonication seeding

    Science.gov (United States)

    Bogdanowicz, R.; Śmietana, M.; Gnyba, M.; Gołunski, Ł.; Ryl, J.; Gardas, M.

    2014-09-01

    In this paper, the growth of polycrystalline chemical vapour deposition (CVD) diamond thin films on fused silica optical fibres has been investigated. The research results show that the effective substrate seeding process can lower defect nucleation, and it simultaneously increases surface encapsulation. However, the growth process on glass requires high seeding density. The effects of suspension type and ultrasonic power were the specific objects of investigation. In order to increase the diamond density, glass substrates were seeded using a high-power sonication process. The highest applied power of sonotrode reached 72 W during the performed experiments. The two, most common diamond seeding suspensions were used, i.e. detonation nanodiamond dispersed in (a) dimethyl sulfoxide and (b) deionised water. The CVD diamond nucleation and growth processes were performed using microwave plasma assisted chemical vapour deposition system. Next, the seeding efficiency was determined and compared using the numerical analysis of scanning electron microscopy images. The molecular composition of nucleated diamond was examined with micro-Raman spectroscopy. The sp3/sp2 band ratio was calculated using Raman spectra deconvolution method. Thickness, roughness, and optical properties of the nanodiamond films in UV-vis wavelength range were investigated by means of spectroscopic ellipsometry. It has been demonstrated that the high-power sonication process can improve the seeding efficiency on glass substrates. However, it can also cause significant erosion defects at the fibre surface. We believe that the proposed growth method can be effectively applied to manufacture the novel optical fibre sensors. Due to high chemical and mechanical resistance of CVD diamond films, deposition of such films on the sensors is highly desirable. This method enables omitting the deposition of an additional adhesion interlayer at the glass-nanocrystalline interface, and thus potentially increases

  11. Controlling the resistivity gradient in chemical vapor deposition-deposited aluminum-doped zinc oxide

    NARCIS (Netherlands)

    Ponomarev, M. V.; Verheijen, M. A.; Keuning, W.; M. C. M. van de Sanden,; Creatore, M.

    2012-01-01

    Aluminum-doped ZnO (ZnO:Al) grown by chemical vapor deposition (CVD) generally exhibit a major drawback, i.e., a gradient in resistivity extending over a large range of film thickness. The present contribution addresses the plasma-enhanced CVD deposition of ZnO: Al layers by focusing on the control

  12. CVD Diamond Detector Stability Issues for Operation at the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Schmid, G J; Koch, J A; Moran, M J; Lerche, R A; Izumi, N; Phillips, T W; Glebov, V Y; Sangster, T C; Stoeckl, C

    2003-08-22

    Synthetic diamond crystals produced by the Chemical Vapor Deposition (CVD) technique can serve as fast, radiation hard, neutron sensors for the National Ignition Facility (NIF). Here we explore the stability issues, such as charge trapping and high-flux saturation, that will be relevant to operation at the NIF.

  13. Modelling and analysis of CVD processes in porous media for ceramic composite preparation

    NARCIS (Netherlands)

    Lin, Y.S.; Burggraaf, A.J.

    1991-01-01

    A continuum phenomenological model is presented to describe chemical vapour deposition (CVD) of solid product inside porous substrate media for the preparation of reinforced ceramic-matrix composites [by the chemical vapour infiltration (CVI) process] and ceramic membrane composites (by a modified C

  14. Control of Reaction Surface in Low Temperature CVD to Enhance Nucleation and Conformal Coverage

    Science.gov (United States)

    Kumar, Navneet

    2009-01-01

    The Holy Grail in CVD community is to find precursors that can afford the following: good nucleation on a desired substrate and conformal deposition in high AR features. Good nucleation is not only necessary for getting ultra-thin films at low thicknesses; it also offers films that are smooth at higher thickness values. On the other hand,…

  15. Advanced deposition model for thermal activated chemical vapor deposition

    Science.gov (United States)

    Cai, Dang

    Thermal Activated Chemical Vapor Deposition (TACVD) is defined as the formation of a stable solid product on a heated substrate surface from chemical reactions and/or dissociation of gaseous reactants in an activated environment. It has become an essential process for producing solid film, bulk material, coating, fibers, powders and monolithic components. Global market of CVD products has reached multi billions dollars for each year. In the recent years CVD process has been extensively used to manufacture semiconductors and other electronic components such as polysilicon, AlN and GaN. Extensive research effort has been directed to improve deposition quality and throughput. To obtain fast and high quality deposition, operational conditions such as temperature, pressure, fluid velocity and species concentration and geometry conditions such as source-substrate distance need to be well controlled in a CVD system. This thesis will focus on design of CVD processes through understanding the transport and reaction phenomena in the growth reactor. Since the in situ monitor is almost impossible for CVD reactor, many industrial resources have been expended to determine the optimum design by semi-empirical methods and trial-and-error procedures. This approach has allowed the achievement of improvements in the deposition sequence, but begins to show its limitations, as this method cannot always fulfill the more and more stringent specifications of the industry. To resolve this problem, numerical simulation is widely used in studying the growth techniques. The difficulty of numerical simulation of TACVD crystal growth process lies in the simulation of gas phase and surface reactions, especially the latter one, due to the fact that very limited kinetic information is available in the open literature. In this thesis, an advanced deposition model was developed to study the multi-component fluid flow, homogeneous gas phase reactions inside the reactor chamber, heterogeneous surface

  16. Photoelectronic properties of hydrogenated amorphous silicon films deposited by R. F sputtering and glow discharge methods

    Energy Technology Data Exchange (ETDEWEB)

    Abdel-Rahman, M.; Madkour, H. (Faculty of Science, Aswan (Egypt)); Hassan, H.H.; El-Desouki, S. (Cairo Univ., Giza (Egypt))

    1989-09-01

    Hydrogenated amorphous silicon films a-Si:H were deposited by both R.F. sputtering in a planar magnetron configuration and glow discharge methods on Corning glass substrates at different substrate temperatures. The dc and ac photoconductivities of the deposited films were extensively studied as a function of temperature, photon energy and photo-excitation intensity. The results showed that, the dark and photoconductivities have different dependency regions on temperature with different activation energies in the range of 0.08-0.20 eV. It has been also found that the photoconductivity is influenced by the method of deposition and the deposition parameters, indicating that the density of gap states is sensitive to the deposition conditions. The photoconductivity ({sigma}{sub ph}) has a power dependence on the illumination intensity (I) of the form {sigma}{sub ph} {alpha} I {sup {nu}}, where {nu} is a constant and was found also to be increase with temperature.

  17. CVD 908, CVD 908-htrA, and CVD 909 live oral typhoid vaccines: a logical progression.

    Science.gov (United States)

    Tacket, Carol O; Levine, Myron M

    2007-07-15

    Typhoid fever remains an important public health problem in many parts of the world. Despite the availability of oral Ty21a (Vivotif; Berna Biotech) and parenteral Vi polysaccharide vaccine (Typhim Vi; Aventis Pasteur), improved typhoid fever vaccines have been sought. These include a series of vaccine candidates developed at the Center for Vaccine Development, University of Maryland, based on attenuation of Salmonella enterica serovar Typhi by deletions in the aroC, aroD, and htrA genes. These vaccine candidates, designated "CVD 908," "CVD 908-htrA," and "CVD 909," have been developed and tested in volunteers with variable success. This review summarizes the clinical data that directed the logical progression of this vaccine development strategy.

  18. Atmospheric Deposition: Sampling Procedures, Analytical Methods, and Main Recent Findings from the Scientific Literature

    Directory of Open Access Journals (Sweden)

    M. Amodio

    2014-01-01

    Full Text Available The atmosphere is a carrier on which some natural and anthropogenic organic and inorganic chemicals are transported, and the wet and dry deposition events are the most important processes that remove those chemicals, depositing it on soil and water. A wide variety of different collectors were tested to evaluate site-specificity, seasonality and daily variability of settleable particle concentrations. Deposition fluxes of POPs showed spatial and seasonal variations, diagnostic ratios of PAHs on deposited particles, allowed the discrimination between pyrolytic or petrogenic sources. Congener pattern analysis and bulk deposition fluxes in rural sites confirmed long-range atmospheric transport of PCDDs/Fs. More and more sophisticated and newly designed deposition samplers have being used for characterization of deposited mercury, demonstrating the importance of rain scavenging and the relatively higher magnitude of Hg deposition from Chinese anthropogenic sources. Recently biological monitors demonstrated that PAH concentrations in lichens were comparable with concentrations measured in a conventional active sampler in an outdoor environment. In this review the authors explore the methodological approaches used for the assessment of atmospheric deposition, from the analysis of the sampling methods, the analytical procedures for chemical characterization of pollutants and the main results from the scientific literature.

  19. Dry deposition of sulphur on the Mpumalanga highveld: a pilot study using the inferential method

    CSIR Research Space (South Africa)

    Zunckel, M

    1996-10-01

    Full Text Available A pilot study which uses the inferential method to estimate dry deposition of sulphur on the central Mpumalanga highveld is discussed in this paper. Ambient concentrations of sulphur dioxide, particulates and micro-meteorological measurements from 2...

  20. Large-Scale Graphene Film Deposition for Monolithic Device Fabrication

    Science.gov (United States)

    Al-shurman, Khaled

    Since 1958, the concept of integrated circuit (IC) has achieved great technological developments and helped in shrinking electronic devices. Nowadays, an IC consists of more than a million of compacted transistors. The majority of current ICs use silicon as a semiconductor material. According to Moore's law, the number of transistors built-in on a microchip can be double every two years. However, silicon device manufacturing reaches its physical limits. To explain, there is a new trend to shrinking circuitry to seven nanometers where a lot of unknown quantum effects such as tunneling effect can not be controlled. Hence, there is an urgent need for a new platform material to replace Si. Graphene is considered a promising material with enormous potential applications in many electronic and optoelectronics devices due to its superior properties. There are several techniques to produce graphene films. Among these techniques, chemical vapor deposition (CVD) offers a very convenient method to fabricate films for large-scale graphene films. Though CVD method is suitable for large area growth of graphene, the need for transferring a graphene film to silicon-based substrates is required. Furthermore, the graphene films thus achieved are, in fact, not single crystalline. Also, graphene fabrication utilizing Cu and Ni at high growth temperature contaminates the substrate that holds Si CMOS circuitry and CVD chamber as well. So, lowering the deposition temperature is another technological milestone for the successful adoption of graphene in integrated circuits fabrication. In this research, direct large-scale graphene film fabrication on silicon based platform (i.e. SiO2 and Si3N4) at low temperature was achieved. With a focus on low-temperature graphene growth, hot-filament chemical vapor deposition (HF-CVD) was utilized to synthesize graphene film using 200 nm thick nickel film. Raman spectroscopy was utilized to examine graphene formation on the bottom side of the Ni film

  1. Method for Predicting Which Customers' Time Deposit Balances Will Increase

    Science.gov (United States)

    Ono, Toshiyuki; Yoshikawa, Hiroshi; Morita, Masahiro; Komoda, Norihisa

    This paper proposes a method of predicting which customers' account balances will increase by using data mining to effectively and efficiently promote sales. Prediction by mining all the data in a business is difficult because of much time required to collect, process, and calculate it. The selection of which features are used for prediction is a critical issue. We propose a method of selecting features to improve the accuracy of prediction within practical time limits. It consists of three parts: (1) converting collected features into financial behavior features that reflect customer actions, (2) extracting features affecting increases in account balances from these collected and financial behavior features, and (3) predicting customers whose account balances will increase based on the extracted features. We found the accuracy of prediction in an experiment with our method to be higher than with other conventional methods.

  2. High-temperature CVD for crystalline-silicon thin-film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Faller, F.R.; Hurrle, A.

    1999-10-01

    The fundamentals of thermal CVD for the deposition of silicon at high temperatures are briefly discussed and applied to the conditions in the CVD system that the authors have constructed and characterized. The system fulfills basic requirements to be met for solar cell application; solar cells made from epitaxial layers on various substrates were fabricated. The high-quality cells achieved 17.6% efficiency proving the excellent performance of the system, the cells on economically relevant substrates achieved 8% efficiency which still needs improvement.

  3. Electrical phase change of CVD-grown Ge-Sb-Te thin film device

    OpenAIRE

    Huang, C.C.; B. Gholipour; Ou, J.Y.; Knight, K.J.; Hewak, D. W.

    2011-01-01

    A prototype Ge-Sb-Te thin film phase-change memory device has been fabricated and reversible threshold and phase change switching demonstrated electrically, with a threshold voltage of 1.5 – 1.7 V. The Ge-Sb-Te thin film was fabricated by chemical vapour deposition (CVD) at atmospheric pressure using GeCl4, SbCl5, and Te precursors with reactive gas H2 at reaction temperature 780 °C and substrate temperature 250 °C. The surface morphology and composition of the CVD-grown Ge-Sb-Te thin film ha...

  4. Aligned carbon nanotubes catalytically grown on iron-based nanoparticles obtained by laser-induced CVD

    OpenAIRE

    Le Normand, Francois; Cojocaru, Costel Sorin; Ersen, Ovidiu; Legagneux, Pierre; Gangloff, Laurent; Fleaca, C.; Alexandrescu, Rodica; Dumitrache, Florin; Morjan, Ion

    2007-01-01

    International audience; Iron-based nanoparticles are prepared by a laser-induced chemical vapor deposition (CVD) process. They are characterized as body-centered Fe and Fe2O3 (maghemite/magnetite) particles with sizes ::;5 and 10 nm, respectively. The Fe particles are embedded in a protective carbon matrix. Both kind of particles are dispersed by spin-coating on SiO2/Si(1 0 0) flat substrates. They are used as catalyst to grow carbon nanotubes by a plasma- and filaments-assisted catalytic CVD...

  5. Knowledge of risk factors for diabetes or cardiovascular disease (CVD) is poor among individuals with risk factors for CVD.

    Science.gov (United States)

    Kilkenny, Monique F; Dunstan, Libby; Busingye, Doreen; Purvis, Tara; Reyneke, Megan; Orgill, Mary; Cadilhac, Dominique A

    2017-01-01

    There is limited evidence on whether having pre-existing cardiovascular disease (CVD) or risk factors for CVD such as diabetes, ensures greater knowledge of risk factors important for motivating preventative behaviours. Our objective was to compare knowledge among the Australian public participating in a health check program and their risk status. Data from the Stroke Foundation 'Know your numbers' program were used. Staff in community pharmacies provided opportunistic health checks (measurement of blood pressure and diabetes risk assessment) among their customers. Participants were categorised: 1) CVD ± risk of CVD: history of stroke, heart disease or kidney disease, and may have risk factors; 2) risk of CVD only: reported having high blood pressure, high cholesterol, diabetes or atrial fibrillation; and 3) CVD risk free (no CVD or risk of CVD). Multivariable logistic regression analyses were performed including adjustment for age and sex. Among 4,647 participants, 12% had CVD (55% male, 85% aged 55+ years), 47% were at risk of CVD (40% male, 72% 55+ years) and 41% were CVD risk free (33% male, 27% 55+ years). Participants with CVD (OR: 0.66; 95% CI: 0.55, 0.80) or risk factors for CVD (OR: 0.65; 95% CI: 0.57, 0.73) had poorer knowledge of the risk factors for diabetes/CVD compared to those who were CVD risk free. After adjustment, only participants with risk factors for CVD (OR: 0.80; 95% CI: 0.69, 0.93) had poorer knowledge. Older participants (55+ years) and men had poorer knowledge of diabetes/CVD risk factors and complications of diabetes. Participants with poorer knowledge of risk factors were older, more often male or were at risk of developing CVD compared with those who were CVD risk free. Health education in these high risk groups should be a priority, as diabetes and CVD are increasing in prevalence throughout the world.

  6. The Charge Collection Properties of CVD Diamond

    CERN Document Server

    Behnke, T; Oh, A; Steuerer, J; Wagner, A; Zeuner, W; Behnke, Ties; Hüntemeyer, Petra; Oh, Alexander; Steuerer, Johannes; Wagner, Albrecht; Zeuner, Wolfram

    1998-01-01

    The charge collection properties of CVD diamond have been investigated with ionising radiation. In this study two CVD diamond samples, prepared with electrical contacts have been used as solid state ionisation chambers. The diamonds have been studied with beta particles and 10 keV photons, providing a homogeneous ionisation density and with protons and alpha particles which are absorbed in a thin surface layer. For the latter case a strong decrease of the signal as function of time is observed, which is attributed to polarisation effects inside the diamond. Spatially resolved measurements with protons show a large variation of the charge collection efficiency, whereas for photons and minimum ionising particles the response is much more uniform and in the order of 18%. These results indicate that the applicability of CVD diamond as a position sensitive particle detector depends on the ionisation type and appears to be promising for homogeneous ionisation densities as provided by relativistic charged particles.

  7. Substrate Strengthening of CVD Coated Steels

    Institute of Scientific and Technical Information of China (English)

    O.Kessler; M.Heidkamp; F.Hoffmann; P.Mayr

    2004-01-01

    Properties of components and tools can be improved by the combination of coating and heat treatment processes due to the addition of single process advantages and due to the utilization of process interactions. Several low and high alloyed, structural and tool steels (AISI 4140, 52100, H13, A2, D2, etc.) have been treated by CVD-TiN-coating plus laser beam hardening respectively carburizing plus CVD-TiN-coating. Homogeneous, dense TiN-coatings with high hardness,high compressive residual stresses and good adhesion were supported by high strength substrate surfaces. Especially CVD plus laser beam hardening offers the possibility to reduce distortion due to the small heated surface volume.

  8. Cutting characteristics of dental diamond burs made with CVD technology Características de corte de pontas odontológicas diamantadas obtidas pela tecnologia CVD

    Directory of Open Access Journals (Sweden)

    Luciana Monti Lima

    2006-04-01

    Full Text Available The aim of this study was to determine the cutting ability of chemical vapor deposition (CVD diamond burs coupled to an ultrasonic dental unit handpiece for minimally invasive cavity preparation. One standard cavity was prepared on the mesial and distal surfaces of 40 extracted human third molars either with cylindrical or with spherical CVD burs. The cutting ability was compared regarding type of substrate (enamel and dentin and direction of handpiece motion. The morphological characteristics, width and depth of the cavities were analyzed and measured using scanning electron micrographs. Statistical analysis using the Kruskal-Wallis test (p O objetivo deste estudo foi determinar a habilidade de corte das pontas de diamante obtidas pelo processo de deposição química a vapor (CVD associadas ao aparelho de ultra-som no preparo cavitário minimamente invasivo. Uma cavidade padronizada foi preparada nas faces mesial e distal de 40 terceiros molares, utilizando-se pontas de diamante CVD cilíndrica e esférica. A habilidade de corte foi comparada quanto ao tipo de substrato (esmalte e dentina e quanto à direção do movimento realizado com a ponta. As características morfológicas, a largura e profundidade das cavidades foram analisadas e medidas em microscopia eletrônica de varredura. A análise estatística pelo teste de Kruskal-Wallis (p < 0,05 revelou que a largura e profundidade das cavidades foram significativamente maiores em dentina. Cavidades mais largas foram obtidas quando se utilizou a ponta de diamante CVD cilíndrica, e mais profundas quando a ponta esférica foi empregada. A direção do movimento da ponta não influenciou o tamanho das cavidades, sendo os cortes produzidos pelas pontas de diamante CVD precisos e conservadores.

  9. Carbon Nanotubes by CVD and Applications

    Science.gov (United States)

    Cassell, Alan; Delzeit, Lance; Nguyen, Cattien; Stevens, Ramsey; Han, Jie; Meyyappan, M.; Arnold, James O. (Technical Monitor)

    2001-01-01

    Carbon nanotube (CNT) exhibits extraordinary mechanical and unique electronic properties and offers significant potential for structural, sensor, and nanoelectronics applications. An overview of CNT, growth methods, properties and applications is provided. Single-wall, and multi-wall CNTs have been grown by chemical vapor deposition. Catalyst development and optimization has been accomplished using combinatorial optimization methods. CNT has also been grown from the tips of silicon cantilevers for use in atomic force microscopy.

  10. Strain Release Induced Novel Fluorescence Variation in CVD-Grown Monolayer WS2 Crystals.

    Science.gov (United States)

    Feng, Shanghuai; Yang, Ruilong; Jia, Zhiyan; Xiang, Jianyong; Wen, Fusheng; Mu, Congpu; Nie, Anmin; Zhao, Zhisheng; Xu, Bo; Tao, Chenggang; Tian, Yongjun; Liu, Zhongyuan

    2017-10-04

    Tensile strain is intrinsic to monolayer crystals of transition metal disulfides such as Mo(W)S2 grown on oxidized silicon substrates by chemical vapor deposition (CVD) owing to the much larger thermal expansion coefficient of Mo(W)S2 than that of silica. Here we report fascinating fluorescent variation in intensity with aging time in CVD-grown triangular monolayer WS2 crystals on SiO2 (300 nm)/Si substrates and formation of interesting concentric triangular fluorescence patterns in monolayer crystals of large size. The novel fluorescence aging behavior is recognized to be induced by the partial release of intrinsic tensile strain after CVD growth and the induced localized variations or gradients of strain in the monolayer crystals. The results demonstrate that strain has a dramatic impact on the fluorescence and photoluminescence of monolayer WS2 crystals and thus could potentially be utilized to tune electronic and optoelectronic properties of monolayer transition metal disulfides.

  11. Response of CVD Diamond Detectors to 14 MeV Neutrons

    CERN Document Server

    Weiss, C; Gagnon-Moisan, F; Kasper, A; Lucke, A; Schuhmacher, H; Weierganz, M; Zimba, A

    2012-01-01

    A series of measurements was taken at the Physikalisch-Technische Bundesanstalt (PTB) Braunschweig [1] using the 14 MeV neutron beam at the Van der Graaf accelerator with chemical vapor deposition (CVD) diamond detectors, in preparation of an upcoming (n, ) cross-section measurement [2] at the CERN-n TOF experiment [3, 4]. A single-crystal (sCVD) as well as a poly-crystalline (pCVD) diamond detector were used for the measurements. The response of both materials to the mono-energetic neutron beam was studied, also with the prospect for future applications in plasma diagnostics for fusion research. The results of the measurements are presented in this report.

  12. Relationship between texture and residual macro-strain in CVD diamond films based on phenomenological analysis

    Institute of Scientific and Technical Information of China (English)

    Weimin Mao; Hongxi Zhu; Leng Chen; Huiping Feng

    2008-01-01

    The relationship between texture and elastic properties of chemical vapor deposition (CVD) diamond films was analyzed based on the phenomenological theory, which reveals the influence of crystalline orientation and texture on the residual macro-strain and macro-stress. The phenomenological calculations indicated that the difference in Young's modulus could be 15% in single dia- mond crystals and 5% in diamond films with homogeneously distributed strong fiber texture. The experimentally measured residual strains of free-standing CVD diamond films were in good agreement with the correspondingly calculated Young's modulus in con- nection with the multi-fiber textures in the fills, though the difference in Young's modulus induced by texture was only around 1%. It is believed that texture should be one of the important factors influencing the residual stress and strain of CVD diamond films.

  13. Macroparticles Reduction Using Filter Free Cathodic Vacuum Arc Deposition Method in ZnO Thin Films.

    Science.gov (United States)

    Yuvakkumar, R; Peranantham, P; Nathanael, A Joseph; Nataraj, D; Mangalaraj, D; Hong, Sun Ig

    2015-03-01

    We report a new method to reduce macroparticles in ZnO thin films using filter free cathodic vacuum arc deposition without using any cooling arrangements operated at low arc current. The detailed mechanism has been proposed to reduce macroparticles during thin film deposition. The successful reduction of macroparticles was confirmed employing FESEM-EDX studies. FESEM images of ZnO thin films deposited with cathode spot to substrate distance from 10 to 20 cm revealed that the population of the macroparticles were reduced with the increase of cathode spot to substrate distances at low arc current. The prepared ZnO films were characterised and showed good structural and optical properties.

  14. Friction Properties of Polished Cvd Diamond Films Sliding against Different Metals

    Science.gov (United States)

    Lin, Zichao; Sun, Fanghong; Shen, Bin

    2016-11-01

    Owing to their excellent mechanical and tribological properties, like the well-known extreme hardness, low coefficient of friction and high chemical inertness, chemical vapor deposition (CVD) diamond films have found applications as a hard coating for drawing dies. The surface roughness of the diamond films is one of the most important attributes to the drawing dies. In this paper, the effects of different surface roughnesses on the friction properties of diamond films have been experimentally studied. Diamond films were fabricated using hot filament CVD. The WC-Co (Co 6wt.%) drawing dies were used as substrates. A gas mixture of acetone and hydrogen gas was used as the feedstock gas. The CVD diamond films were polished using mechanical polishing. Polished diamond films with three different surface roughnesses, as well as the unpolished diamond film, were fabricated in order to study the tribological performance between the CVD diamond films and different metals with oil lubrication. The unpolished and polished CVD diamond films are characterized with scanning electron microscope (SEM), atomic force microscope (AFM), surface profilometer, Raman spectrum and X-ray diffraction (XRD). The friction examinations were carried out by using a ball-on-plate type reciprocating friction tester. Low carbide steel, stainless steel, copper and aluminum materials were used as counterpart balls. Based on this study, the results presented the friction coefficients between the polished CVD films and different metals. The friction tests demonstrate that the smooth surface finish of CVD diamond films is beneficial for reducing their friction coefficients. The diamond films exhibit low friction coefficients when slid against the stainless steel balls and low carbide steel ball, lower than that slid against copper ball and aluminum ball, attributed to the higher ductility of copper and aluminum causing larger amount of wear debris adhering to the sliding interface and higher adhesive

  15. Toward an Objective Method to Distinguishing Deltaic Depositional Environments

    Science.gov (United States)

    Block, A. E.; Perlmutter, M.; Thorne, J.; Pyrcz, M.

    2014-12-01

    The most commonly used method of delta classification is to interpret formation processes from observation of the resulting geomorphic features, and to place the delta on a ternary diagram based on the relative dominance of the associated wave, tidal, or fluvial influences. This system has worked well and has been in use for more than 40 years - but it suffers from the subjectivity inherent to visual interpretation techniques. We aim to establish an alternative classification method that is both objective and reliable for the classification of deltaic systems. At the corner stone of our current approach, we use the statistic of lacunarity to quantitatively describe the variability of deltaic footprints across a wide range of spatial scales. Lacunarity has been used for more than 20 years to identify and characterize stratigraphic patterns, and is currently in use in such diverse fields as urban planning and medicine to characterize spatial distribution of properties. Here, we apply lacunarity to satellite images of modern deltas in order to quantitatively describe the distribution of land and water at scales ranging from the data resolution to that of the entire system. The results of our lacunarity analyses provide the basis for a new, objective, system of delta classification.

  16. Deposition and Characterization Of Nanocrystalline Silver Thin Films By Using SILAR Method

    Science.gov (United States)

    Rohom, A. B.; Sartale, S. D.

    2011-07-01

    Nanocrystalline silver thin films were deposited on glass substrate by using Successive Ionic Layer Adsorption and Reduction (SILAR) method. Silver nitrate and hydrazine hydrate (HyH) were used as precursors. The deposited silver thin films were characterized by using X-ray diffraction (XRD), UV-visible-NIR absorption spectroscopy and scanning electron microscopy (SEM) techniques. Effect of concentration of HyH on properties of SILAR grown silver thin films has been extensively studied.

  17. Characterization of an innovative method for RuO2 deposition using Electron Microscopy

    DEFF Research Database (Denmark)

    Cavalca, Filippo

    Many photocatalysts work better or exclusively when a suitable cocatalyst, such as RuO2, is deposited on their surface. An innovative method of RuO2 deposition has been found to improve the performance of photocatalysts such as (Ga1-xZnx)(N1-xOx), WO3, SrTiO3 and TiO2. Here we use high angle annu...

  18. Comparison of methods for evaluation of aerosol deposition in the model of human lungs

    Directory of Open Access Journals (Sweden)

    Belka Miloslav

    2014-03-01

    Full Text Available It seems to be very convenient to receive a medicine by inhalation instead of injection. Unfortunately transport of particles and targeted delivery of a drug in human respiratory airways is very complicated task. Therefore we carried out experiments and tested different methods for evaluation of particle deposition in a model of human lungs. The model included respiratory airways from oral cavity to 7th generation of branching. Particles were dispersed by TSI Small-scale Powder Disperser 3433 and delivered to the model. The model was disassembled into segments after the deposition of the particles and local deposition was measured. Two methods were used to analyse the samples, fluorescence spectroscopy and optical microscopy. The first method was based on measuring the intensity of luminescence, which represented the particle deposition. The second method used the optical microscope with phase-contrast objective. A dispersion of isopropanol and particles was filtrated using a vacuum filtration unit, a filter was placed on glass slide and made transparent. The particles on the filter were counted manually and the deposition was calculated afterwards. The results of the methods were compared and both methods proved to be useful.

  19. Nucleation and growth of single layer graphene on electrodeposited Cu by cold wall chemical vapor deposition

    Science.gov (United States)

    Das, Shantanu; Drucker, Jeff

    2017-03-01

    The nucleation density and average size of graphene crystallites grown using cold wall chemical vapor deposition (CVD) on 4 μm thick Cu films electrodeposited on W substrates can be tuned by varying growth parameters. Growth at a fixed substrate temperature of 1000 °C and total pressure of 700 Torr using Ar, H2 and CH4 mixtures enabled the contribution of total flow rate, CH4:H2 ratio and dilution of the CH4/H2 mixture by Ar to be identified. The largest variation in nucleation density was obtained by varying the CH4:H2 ratio. The observed morphological changes are analogous to those that would be expected if the deposition rate were varied at fixed substrate temperature for physical deposition using thermal evaporation. The graphene crystallite boundary morphology progresses from irregular/jagged through convex hexagonal to regular hexagonal as the effective C deposition rate decreases. This observation suggests that edge diffusion of C atoms along the crystallite boundaries, in addition to H2 etching, may contribute to shape evolution of the graphene crystallites. These results demonstrate that graphene grown using cold wall CVD follows a nucleation and growth mechanism similar to hot wall CVD. As a consequence, the vast knowledge base relevant to hot wall CVD may be exploited for graphene synthesis by the industrially preferable cold wall method.

  20. Epitaxial nucleation of CVD bilayer graphene on copper.

    Science.gov (United States)

    Song, Yenan; Zhuang, Jianing; Song, Meng; Yin, Shaoqian; Cheng, Yu; Zhang, Xuewei; Wang, Miao; Xiang, Rong; Xia, Yang; Maruyama, Shigeo; Zhao, Pei; Ding, Feng; Wang, Hongtao

    2016-12-08

    Bilayer graphene (BLG) has emerged as a promising candidate for next-generation electronic applications, especially when it exists in the Bernal-stacked form, but its large-scale production remains a challenge. Here we present an experimental and first-principles calculation study of the epitaxial chemical vapor deposition (CVD) nucleation process for Bernal-stacked BLG growth on Cu using ethanol as a precursor. Results show that a carefully adjusted flow rate of ethanol can yield a uniform BLG film with a surface coverage of nearly 90% and a Bernal-stacking ratio of nearly 100% on ordinary flat Cu substrates, and its epitaxial nucleation of the second layer is mainly due to the active CH3 radicals with the presence of a monolayer-graphene-covered Cu surface. We believe that this nucleation mechanism will help clarify the formation of BLG by the epitaxial CVD process, and lead to many new strategies for scalable synthesis of graphene with more controllable structures and numbers of layers.

  1. Oxide Dispersion Strengthened Iron Aluminide by CVD Coated Powders

    Energy Technology Data Exchange (ETDEWEB)

    Asit Biswas Andrew J. Sherman

    2006-09-25

    This I &I Category2 program developed chemical vapor deposition (CVD) of iron, aluminum and aluminum oxide coated iron powders and the availability of high temperature oxidation, corrosion and erosion resistant coating for future power generation equipment and can be used for retrofitting existing fossil-fired power plant equipment. This coating will provide enhanced life and performance of Coal-Fired Boilers components such as fire side corrosion on the outer diameter (OD) of the water wall and superheater tubing as well as on the inner diameter (ID) and OD of larger diameter headers. The program also developed a manufacturing route for readily available thermal spray powders for iron aluminide coating and fabrication of net shape component by powder metallurgy route using this CVD coated powders. This coating can also be applid on jet engine compressor blade and housing, industrial heat treating furnace fixtures, magnetic electronic parts, heating element, piping and tubing for fossil energy application and automotive application, chemical processing equipment , heat exchanger, and structural member of aircraft. The program also resulted in developing a new fabrication route of thermal spray coating and oxide dispersion strengthened (ODS) iron aluminide composites enabling more precise control over material microstructures.

  2. Organic solar cells using CVD-grown graphene electrodes

    Science.gov (United States)

    Kim, Hobeom; Bae, Sang-Hoon; Han, Tae-Hee; Lim, Kyung-Geun; Ahn, Jong-Hyun; Lee, Tae-Woo

    2014-01-01

    We report on the development of flexible organic solar cells (OSCs) incorporating graphene sheets synthesized by chemical vapor deposition (CVD) as transparent conducting electrodes on polyethylene terephthalate (PET) substrates. A key barrier that must be overcome for the successful fabrication of OSCs with graphene electrodes is the poor-film properties of water-based poly(3,4-ethylenedioxythiphene):poly(styrenesulfonate) (PEDOT:PSS) when coated onto hydrophobic graphene surfaces. To form a uniform PEDOT:PSS film on a graphene surface, we added perfluorinated ionomers (PFI) to pristine PEDOT:PSS to create ‘GraHEL’, which we then successfully spin coated onto the graphene surface. We systematically investigated the effect of number of layers in layer-by-layer stacked graphene anode of an OSC on the performance parameters including the open-circuit voltage (Voc), short-circuit current (Jsc), and fill factor (FF). As the number of graphene layers increased, the FF tended to increase owing to lower sheet resistance, while Jsc tended to decrease owing to the lower light absorption. In light of this trade-off between sheet resistance and transmittance, we determined that three-layer graphene (3LG) represents the best configuration for obtaining the optimal power conversion efficiency (PCE) in OSC anodes, even at suboptimal sheet resistances. We finally developed efficient, flexible OSCs with a PCE of 4.33%, which is the highest efficiency attained so far by an OSC with CVD-grown graphene electrodes to the best of our knowledge.

  3. CVD Rhenium Engines for Solar-Thermal Propulsion Systems

    Science.gov (United States)

    Williams, Brian E.; Fortini, Arthur J.; Tuffias, Robert H.; Duffy, Andrew J.; Tucker, Stephen P.

    1999-01-01

    Solar-thermal upper-stage propulsion systems have the potential to provide specific impulse approaching 900 seconds, with 760 seconds already demonstrated in ground testing. Such performance levels offer a 100% increase in payload capability compared to state-of-the-art chemical upper-stage systems, at lower cost. Although alternatives such as electric propulsion offer even greater performance, the 6- to 18- month orbital transfer time is a far greater deviation from the state of the art than the one to two months required for solar propulsion. Rhenium metal is the only material that is capable of withstanding the predicted thermal, mechanical, and chemical environment of a solar-thermal propulsion device. Chemical vapor deposition (CVD) is the most well-established and cost-effective process for the fabrication of complex rhenium structures. CVD rhenium engines have been successfully constructed for the Air Force ISUS program (bimodal thrust/electricity) and the NASA Shooting Star program (thrust only), as well as under an Air Force SBIR project (thrust only). The bimodal engine represents a more long-term and versatile approach to solar-thermal propulsion, while the thrust-only engines provide a potentially lower weight/lower cost and more near-term replacement for current upper-stage propulsion systems.

  4. CVD-graphene growth on different polycrystalline transition metals

    Directory of Open Access Journals (Sweden)

    M. P. Lavin-Lopez

    2017-01-01

    Full Text Available The chemical vapor deposition (CVD graphene growth on two polycrystalline transition metals (Ni and Cu was investigated in detail using Raman spectroscopy and optical microscopy as a way to synthesize graphene of the highest quality (i.e. uniform growth of monolayer graphene, which is considered a key issue for electronic devices. Key CVD process parameters (reaction temperature, CH4/H2flow rate ratio, total flow of gases (CH4+H2, reaction time were optimized for both metals in order to obtain the highest graphene uniformity and quality. The conclusions previously reported in literature about the performance of low and high carbon solubility metals in the synthesis of graphene and their associated reaction mechanisms, i.e. surface depositionand precipitation on cooling, respectively, was not corroborated by the results obtained in this work. Under the optimal reaction conditions, a large percentage of monolayer graphene was obtained over the Ni foil since the carbon saturation was not complete, allowing carbon atoms to be stored in the bulk metal, which could diffuse forming high quality monolayer graphene at the surface. However, under the optimal reaction conditions, the formation of a non-uniform mixture of few layers and multilayer graphene on the Cu foil was related to the presence of an excess of active carbon atoms on the Cu surface.

  5. Enhanced cold wall CVD reactor growth of horizontally aligned single-walled carbon nanotubes

    Science.gov (United States)

    Mu, Wei; Kwak, Eun-Hye; Chen, Bingan; Huang, Shirong; Edwards, Michael; Fu, Yifeng; Jeppson, Kjell; Teo, Kenneth; Jeong, Goo-Hwan; Liu, Johan

    2016-05-01

    HASynthesis of horizontally-aligned single-walled carbon nanotubes (HA-SWCNTs) by chemical vapor deposition (CVD) directly on quartz seems very promising for the fabrication of future nanoelectronic devices. In comparison to hot-wall CVD, synthesis of HA-SWCNTs in a cold-wall CVD chamber not only means shorter heating, cooling and growth periods, but also prevents contamination of the chamber. However, since most synthesis of HA-SWCNTs is performed in hot-wall reactors, adapting this well-established process to a cold-wall chamber becomes extremely crucial. Here, in order to transfer the CVD growth technology from a hot-wall to a cold-wall chamber, a systematic investigation has been conducted to determine the influence of process parameters on the HA-SWCNT's growth. For two reasons, the cold-wall CVD chamber was upgraded with a top heater to complement the bottom substrate heater; the first reason to maintain a more uniform temperature profile during HA-SWCNTs growth, and the second reason to preheat the precursor gas flow before projecting it onto the catalyst. Our results show that the addition of a top heater had a significant effect on the synthesis. Characterization of the CNTs shows that the average density of HA-SWCNTs is around 1 - 2 tubes/ μm with high growth quality as shown by Raman analysis. [Figure not available: see fulltext.

  6. Can surface preparation with CVD diamond tip influence on bonding to dental tissues?

    Science.gov (United States)

    Aparecido Kawaguchi, Fernando; Brossi Botta, Sergio; Nilo Vieira, Samuel; Steagall Júnior, Washington; Bona Matos, Adriana

    2008-04-01

    This study evaluated the influence of chemical vapor deposition (CVD) tips surface treatments of enamel and dentin on bonding resistance of two adhesive systems. Thirty embedded samples were divided in 12 groups ( n = 10), according to factors: substrate (enamel and dentin), adhesive system [etch-and-rinse (SB) and self-etch]; and the surface treatments (paper discs, impact CVD tips and tangential CVD tip). When CVD tip was used in the impact mode the tip was applied perpendicular to dental surface, while at tangential mode, the tip worked parallel to dental surface. Specimens were tested in tension after 24 h at 0.5 mm/min of cross-head speed. ANOVA results, in MPa showed that in enamel, only adhesive system factor was statistically significant ( p = 0.015) under tested conditions, with higher bond strength observed for SB groups. However, in dentin the best bonding performance was obtained in SE groups ( p = 0.00). In both tested substrates, results did not show statistically significant difference for factors treatment and its interactions. ConclusionsIt may be concluded that CVD-tip surface treatment, in both tested modes, did not influence on adhesion to enamel and dentin. But, it is important to choose adhesive system according to the tissue available to bonding.

  7. CVD diamond pixel detectors for LHC experiments

    Energy Technology Data Exchange (ETDEWEB)

    Wedenig, R.; Adam, W.; Bauer, C.; Berdermann, E.; Bergonzo, P.; Bogani, F.; Borchi, E.; Brambilla, A.; Bruzzi, M.; Colledani, C.; Conway, J.; Dabrowski, W.; Delpierre, P.; Deneuville, A.; Dulinski, W.; Eijk, B. van; Fallou, A.; Fizzotti, F.; Foulon, F.; Friedl, M.; Gan, K.K.; Gheeraert, E.; Grigoriev, E.; Hallewell, G.; Hall-Wilton, R.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kania, D.; Kaplon, J.; Karl, C.; Kass, R.; Knoepfle, K.T.; Krammer, M.; Logiudice, A.; Lu, R.; Manfredi, P.F.; Manfredotti, C.; Marshall, R.D.; Meier, D.; Mishina, M.; Oh, A.; Pan, L.S.; Palmieri, V.G.; Pernicka, M.; Peitz, A.; Pirollo, S.; Polesello, P.; Pretzl, K.; Procario, M.; Re, V.; Riester, J.L.; Roe, S.; Roff, D.; Rudge, A.; Runolfsson, O.; Russ, J.; Schnetzer, S.; Sciortino, S.; Speziali, V.; Stelzer, H.; Stone, R.; Suter, B.; Tapper, R.J.; Tesarek, R.; Trawick, M.; Trischuk, W.; Vittone, E.; Wagner, A.; Walsh, A.M.; Weilhammer, P.; White, C.; Zeuner, W.; Ziock, H.; Zoeller, M.; Blanquart, L.; Breugnion, P.; Charles, E.; Ciocio, A.; Clemens, J.C.; Dao, K.; Einsweiler, K.; Fasching, D.; Fischer, P.; Joshi, A.; Keil, M.; Klasen, V.; Kleinfelder, S.; Laugier, D.; Meuser, S.; Milgrome, O.; Mouthuy, T.; Richardson, J.; Sinervo, P.; Treis, J.; Wermes, N

    1999-08-01

    This paper reviews the development of CVD diamond pixel detectors. The preparation of the diamond pixel sensors for bump-bonding to the pixel readout electronics for the LHC and the results from beam tests carried out at CERN are described.

  8. Method of recovering a soluble salt from an underground deposit

    Energy Technology Data Exchange (ETDEWEB)

    1967-10-18

    This process of solution mining is said to provide an improved method of roof control of the cavity by forming a blanket of oil above the solution and by correlating the blanket thickness with the diameter of the cavity as it is being formed. Nonselective mining is carried out by the continuous injection of water during the contact of sylvinite ore containing less than about 30-40% KC1, followed by periods of selective solvation of an ore containing KC1 in concentrations of 35% or more carried out by the injection of sodium chloride brine. During the latter cycles, crystals of potassium chloride will be selectively dissolved from the ore face, leaving the sodium chloride crystals to fall to the bottom of the cavity together with some displaced chloride originally present in the injected brine. When the rich ore band has been removed, nonselective solution mining using water injection is again resumed until another rich KC1 band is encountered. (21 claims)

  9. Prediction of the properties of PVD/CVD coatings with the use of FEM analysis

    Science.gov (United States)

    Śliwa, Agata; Mikuła, Jarosław; Gołombek, Klaudiusz; Tański, Tomasz; Kwaśny, Waldemar; Bonek, Mirosław; Brytan, Zbigniew

    2016-12-01

    The aim of this paper is to present the results of the prediction of the properties of PVD/CVD coatings with the use of finite element method (FEM) analysis. The possibility of employing the FEM in the evaluation of stress distribution in multilayer Ti/Ti(C,N)/CrN, Ti/Ti(C,N)/(Ti,Al)N, Ti/(Ti,Si)N/(Ti,Si)N, and Ti/DLC/DLC coatings by taking into account their deposition conditions on magnesium alloys has been discussed in the paper. The difference in internal stresses in the zone between the coating and the substrate is caused by, first of all, the difference between the mechanical and thermal properties of the substrate and the coating, and also by the structural changes that occur in these materials during the fabrication process, especially during the cooling process following PVD and CVD treatment. The experimental values of stresses were determined based on X-ray diffraction patterns that correspond to the modelled values, which in turn can be used to confirm the correctness of the accepted mathematical model for testing the problem. An FEM model was established for the purpose of building a computer simulation of the internal stresses in the coatings. The accuracy of the FEM model was verified by comparing the results of the computer simulation of the stresses with experimental results. A computer simulation of the stresses was carried out in the ANSYS environment using the FEM method. Structure observations, chemical composition measurements, and mechanical property characterisations of the investigated materials has been carried out to give a background for the discussion of the results that were recorded during the modelling process.

  10. Growth of aligned ZnO nanowires via modified atmospheric pressure chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yuping; Li, Chengchen [Faculty of Science, Jiangsu University, Zhenjiang, Jiangsu, 212013 (China); Chen, Mingming, E-mail: andychain@live.cn [Faculty of Science, Jiangsu University, Zhenjiang, Jiangsu, 212013 (China); Yu, Xiao; Chang, Yunwei [Faculty of Science, Jiangsu University, Zhenjiang, Jiangsu, 212013 (China); Chen, Anqi [State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics & Information Technology, Sun Yat-Sen University, Guangzhou Higher Education Mega Center (University Town), Guangzhou, 510006 (China); Zhu, Hai, E-mail: zhuhai5@mail.sysu.edu.cn [State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics & Information Technology, Sun Yat-Sen University, Guangzhou Higher Education Mega Center (University Town), Guangzhou, 510006 (China); Tang, Zikang, E-mail: zktang@umac.mo [State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics & Information Technology, Sun Yat-Sen University, Guangzhou Higher Education Mega Center (University Town), Guangzhou, 510006 (China); The Institute of Applied Physics and Materials Engineering, University of Macau, Avenida da Universidade, Taipa, Macau (China)

    2016-12-09

    In this work, we report the growth of high-quality aligned ZnO nanowires via a facile atmospheric pressure chemical vapor deposition (CVD) method. The CVD reactor chamber used was more complicated than a conventional one due to the quartz boats loaded with sources (ZnO/C) and substrates being inserted into a semi-open quartz tube, and then placed inside the CVD reactor. The semi-open quartz tube played a very important role in growing the ZnO nanowires, and demonstrated that the transportation properties of Zn and O vapor differ from those in the conventional CVD reactor chamber. Aligned ZnO nanowires were successfully obtained, though they were only found at substrates located upstream. The very high crystalline quality of the obtained ZnO nanowires was demonstrated by high-resolution transmission electron microscopy and room temperature photoluminescence investigations. Such ZnO nanowires with high crystalline quality may provide opportunities for the fabrication of ZnO-based nano-devices in future. - Highlights: • High-quality aligned ZnO nanowires were obtained via modified chemical vapor deposition under atmospheric pressure. • The semi-open quartz tube plays very important roles in growing ZnO nanowires. • The transportation properties of Zn and O vapor differ from those in the conventional CVD reactor chamber.

  11. Project JADE. Comparative cost analysis for different deposition methods; Projekt JADE. Jaemfoerande kostnadsanalys mellan olika deponeringsmetoder

    Energy Technology Data Exchange (ETDEWEB)

    Ageskog, L. [SWECO VBB VIAK AB, Stockholm (Sweden)

    2001-08-01

    Within the SKB Deep Repository Project, a study called JADE (Comparison of Deposition Methods) has been performed with the purpose of systematically evaluating different deposition methods The study has encompassed the areas of technology, long term performance and safety, and costs. The alternative methods studied are all within the frame of the so-called KBS-3 concept. The present report deals with the comparison regarding costs. The following deposition methods have been studied and compared: deposition in vertical holes (KBS-3 V), single canister deposition in horizontal holes (KBS-3 H) and serial canister deposition in medium long holes (MLH). KBS-3 V constitutes the reference concept for current development and planing activities within SKB. The cost calculations have been performed according to a method called 'the Successive Principle'. The same method is currently used by SKB in the cost analyses reported to the authorities on a yearly basis (the so-called PLAN analyses). The method covers uncertainties of various kinds and presents data in a statistical manner, providing means for a result interpretation in terms of probabilities. Beside the methodology, also technical and cost data have been derived from the PLAN works, mostly from the report PLAN 97, which was forwarded to the authorities in June 1997. Hence, all cost data in the present study refer to price level January 1997. The findings of the present study are compared with the reference method KBS 3 V. (The report also includes comparisons between alternatives within each one of the three principal methods.)

  12. Synthesize of N-doped Carbon nanotube according to gas flow rate by Chemical Vapor Deposition

    Science.gov (United States)

    Kim, J. B.; Kim, C. D.; Kong, S. J.; Kim, J. H.; Min, B. K.; Jung, W. S.; Lee, H. R.

    2011-12-01

    Nitrogen-doped (N-doped) Carbon nanotubes (CNTs) have been prepared by Thermal Chemical Vapor Deposition (CVD). As doping accompanies with the recombination of carbon atoms into CNTs in the CVD process, N atoms can be substitutionally doped into the CNTs lattice, which is hard to realize by other synthetic methods. The synthesis technique and the characteristic analysis of N-doped CNT will move up the industrialization and the basic study of CNT. We will elucidate the basic properties of CNT such as the structural characteristics of the N-doped CNT material and study for the industrial application of the N-doped CNTs to the electrode of fuel cell.

  13. Trimethyl(phenylsilane — a precursor for gas phase processes of SiCx:H film deposition: Synthesis and characterization

    Directory of Open Access Journals (Sweden)

    Evgeniya N. Ermakova

    2015-12-01

    Full Text Available The technique of synthesis and purification of trimethyl(phenylsilane PhSiMe3, allowing to obtain the product with high yield. Individuality of the product was confirmed by elemental analysis for C, H, Si was developed. IR, UV and 1H NMR-spectroscopic studies were used to define its spectral characteristics. Complex thermal analysis and thermogravimetry defined thermoanalytical behavior of PhSiMe3 in an inert atmosphere. Tensimetric studies have shown that the compound has sufficient volatility and thermal stability for use as a precursor in the process of chemical vapor deposition (CVD. The composition and temperature limits of the possible crystalline phase complexes in equilibrium with the gas phase of different composition has been determined by method of thermodynamic modeling. Calculated CVD diagrams allow us to select the optimal conditions of film deposition. The possibility of using trimethyl(phenylsilane in CVD processes for producing dielectric films of hydrogenated silicon carbide has been demonstrated.

  14. Co-deposition methods for the fabrication of organic optoelectronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, Mark E.; Liu, Zhiwei; Wu, Chao

    2016-09-06

    A method for fabricating an OLED by preparing phosphorescent metal complexes in situ is provided. In particular, the method simultaneously synthesizes and deposits copper (I) complexes in an organic light emitting device. Devices comprising such complexes may provide improved photoluminescent and electroluminescent properties.

  15. Preparation of (Bi, Sb) 2S 3 semiconductor films by photochemical deposition method

    Science.gov (United States)

    Sasaki, H.; Shibayama, K.; Ichimura, M.; Masui, K.

    2002-04-01

    The photochemical deposition (PCD) technique has the advantages of economy, the capability of large area deposition and of a fast reaction rate. In this report, the PCD method using UV light of an ultra-high pressure mercury lamp was applied to form (Bi x, Sb 1- x) 2S 3 semiconducting compounds from solutions containing BiCl 3 and/or SbCl 3 Na 2S 2O 3 at pH in the acidic range 1-3. The pH of the solution was adjusted with the addition of dilute HCl solution. The substrate for the film deposition was pretreated onto the commercial pyrex-glass plate surface with the well-known solution agent of Pd activator plus Sn sensitizer. In the PCD process, the film is only deposited onto the irradiated region of the substrate so as to make a pattern using the mask. This deposition process shows the heterogeneous nucleation and growth mechanism on the substrate surface. The deposition rate of the film using a 500 W mercury lamp was about 1 μm/30 min. The crystallization characteristics of the amorphous (Bi 2S 3) deposits were studied by means of X-ray diffraction, thermal analysis (DSC) and optical transmitted spectra evaluation in order to clarify the amorphous to crystal phase transformation. The amorphous deposits showed gradual light absorption in a wide range of optical wavelengths. On the contrary, annealed film showed a sharp absorption edge near 800 nm. The crystallization temperature of the amorphous deposits was about 250-300°C.

  16. In vitro characterization of hydroxyapatite layers deposited by APS and HVOF thermal spraying methods

    Directory of Open Access Journals (Sweden)

    Radu Alexandru Roşu

    2012-03-01

    Full Text Available Titanium alloys are successfully used in medicine as implants due to their high mechanical properties and good biocompatibility. To improve implant osseointegration of titanium alloys, they are covered with hydroxyapatite because of its bioactive properties. Coating the implants with hydroxyapatite by thermal spraying, due to the temperatures developed during the deposition process, the structure can be degraded, leading to formation of secondary phases, such as TCP, TT CP, CaO. The paper presents the experimental results of hydroxyapatite layers deposition by two thermal spraying methods: Atmospheric Plasma Spraying (APS and High Velocity Oxy-Fuel (HVOF. The microstructure of the deposited layers is characterized by X-ray diffraction analysis and electronic microscopy. The bioactivity of the hydroxyapatite layers was investigated in Simulated Body Fluid (SBF by immersing the covered samples deposited by the two thermal spraying methods. In both cases the coatings did not present defects as cracks or microcracks. X-ray diffraction performed on hydroxyapatite deposited layers shows that the structure was strongly influenced by plasma jet temperature, the structure consisting mainly of TCP (Ca3PO42. The samples deposited by HVO F after immersing in SBF lead to formation of biological hydroxyapatite, certifying the good bioactivity of the coatings.

  17. Handbook of thin film deposition processes and techniques principles, methods, equipment and applications

    CERN Document Server

    Seshan, Krishna

    2002-01-01

    New second edition of the popular book on deposition (first edition by Klaus Schruegraf) for engineers, technicians, and plant personnel in the semiconductor and related industries. This book traces the technology behind the spectacular growth in the silicon semiconductor industry and the continued trend in miniaturization over the last 20 years. This growth has been fueled in large part by improved thin film deposition techniques and the development of highly specialized equipment to enable this deposition. The book includes much cutting-edge material. Entirely new chapters on contamination and contamination control describe the basics and the issues-as feature sizes shrink to sub-micron dimensions, cleanliness and particle elimination has to keep pace. A new chapter on metrology explains the growth of sophisticated, automatic tools capable of measuring thickness and spacing of sub-micron dimensions. The book also covers PVD, laser and e-beam assisted deposition, MBE, and ion beam methods to bring together a...

  18. The Effect of Excess Carbon on the Crystallographic, Microstructural, and Mechanical Properties of CVD Silicon Carbide Fibers

    Energy Technology Data Exchange (ETDEWEB)

    Marzik, J V; Croft, W J; Staples, R J; MoberlyChan, W J

    2006-12-05

    Silicon carbide (SiC) fibers made by chemical vapor deposition (CVD) are of interest for organic, ceramic, and metal matrix composite materials due their high strength, high elastic modulus, and retention of mechanical properties at elevated processing and operating temperatures. The properties of SCS-6{trademark} silicon carbide fibers, which are made by a commercial process and consist largely of stoichiometric SiC, were compared with an experimental carbon-rich CVD SiC fiber, to which excess carbon was added during the CVD process. The concentration, homogeneity, and distribution of carbon were measured using energy dispersive x-ray spectroscopy (SEM/EDS). The effect of excess carbon on the tensile strength, elastic modulus, and the crystallographic and microstructural properties of CVD silicon carbide fibers was investigated using tensile testing, x-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM).

  19. CVD Lu(2)O(3):Eu coatings For Advanced Scintillators.

    Science.gov (United States)

    Topping, Stephen G; Sarin, V K

    2009-03-01

    Currently Lu(2)O(3):Eu(3+) scintillators can only be fabricated via hot-pressing and pixelization, which is commercially not viable, thus restricting their use. Chemical vapor deposition is being developed as an alternative manufacturing process. Columnar coatings of Lu(2)O(3):Eu(3+) have been achieved using the halide-CO(2)-H(2) system, clearly signifying feasibility of the CVD process. Characterization of the coatings using high resolution scanning electron microscopy (SEM) and x-ray diffraction (XRD) analysis have been used as an aid to optimize process parameters and attain highly oriented and engineered coating structures. These results have clearly demonstrated that this process can be successfully used to tailor sub-micron columnar growth of Lu(2)O(3):Eu(3+), with the potential of ultra high resolution x-ray imaging.

  20. CVD synthesis of carbon-based metallic photonic crystals

    CERN Document Server

    Zakhidov, A A; Baughman, R H; Iqbal, Z

    1999-01-01

    Three-dimensionally periodic nanostructures on the scale of hundreds of nanometers, known as photonic crystals, are attracting increasing interest because of a number of exciting predicted properties. In particular, interesting behavior should be obtainable for carbon- based structures having a dimensional scale larger than fullerenes and nanotubes, but smaller than graphitic microfibers. We show here how templating of porous opals by chemical vapor deposition (CVD) allows us to obtain novel types of graphitic nanostructures. We describe the synthesis of new cubic forms of carbon having extended covalent connectivity in three dimensions, which provide high electrical conductivity and unit cell dimensions comparable to optical wavelengths. Such materials are metallic photonic crystals that show intense Bragg diffraction. (14 refs).

  1. Method and system for near-field spectroscopy using targeted deposition of nanoparticles

    Science.gov (United States)

    Anderson, Mark S. (Inventor)

    2012-01-01

    There is provided in one embodiment of the invention a method for analyzing a sample material using surface enhanced spectroscopy. The method comprises the steps of imaging the sample material with an atomic force microscope (AFM) to select an area of interest for analysis, depositing nanoparticles onto the area of interest with an AFM tip, illuminating the deposited nanoparticles with a spectrometer excitation beam, and disengaging the AFM tip and acquiring a localized surface enhanced spectrum. The method may further comprise the step of using the AFM tip to modulate the spectrometer excitation beam above the deposited nanoparticles to obtain improved sensitivity data and higher spatial resolution data from the sample material. The invention further comprises in one embodiment a system for analyzing a sample material using surface enhanced spectroscopy.

  2. Towards a general growth model for graphene CVD on transition metal catalysts

    Science.gov (United States)

    Cabrero-Vilatela, Andrea; Weatherup, Robert S.; Braeuninger-Weimer, Philipp; Caneva, Sabina; Hofmann, Stephan

    2016-01-01

    The chemical vapour deposition (CVD) of graphene on three polycrystalline transition metal catalysts, Co, Ni and Cu, is systematically compared and a first-order growth model is proposed which can serve as a reference to optimize graphene growth on any elemental or alloy catalyst system. Simple thermodynamic considerations of carbon solubility are insufficient to capture even basic growth behaviour on these most commonly used catalyst materials, and it is shown that kinetic aspects such as carbon permeation have to be taken into account. Key CVD process parameters are discussed in this context and the results are anticipated to be highly useful for the design of future strategies for integrated graphene manufacture.The chemical vapour deposition (CVD) of graphene on three polycrystalline transition metal catalysts, Co, Ni and Cu, is systematically compared and a first-order growth model is proposed which can serve as a reference to optimize graphene growth on any elemental or alloy catalyst system. Simple thermodynamic considerations of carbon solubility are insufficient to capture even basic growth behaviour on these most commonly used catalyst materials, and it is shown that kinetic aspects such as carbon permeation have to be taken into account. Key CVD process parameters are discussed in this context and the results are anticipated to be highly useful for the design of future strategies for integrated graphene manufacture. Electronic supplementary information (ESI) available: Fig. S1. See DOI: 10.1039/c5nr06873h

  3. GCMS and FTIR studies of by-product inhibited growth and the rate-limiting step in TEOS-based SiO{sub 2} CVD

    Energy Technology Data Exchange (ETDEWEB)

    Bartram, M.E.; Moffat, H.K. [Sandia National Labs., Albuquerque, NM (United States). Chemical Processing Science Dept.

    1995-04-01

    To improve process reliability and deposition methods, it is essential to identify the rate-limiting step in TEOS-based SiO{sub 2} CVD and its dependence on process conditions. For this purpose, experiments designed to evaluate by-product inhibition effects and to identify the rate-limiting step in TEOS decomposition have been carried out in a research reactor using GCMS and FTIR. By repetitively sampling a series of reactions in which TEOS was first mixed with ethylene, ethanol, and water in the gas-phase, GCMS was used to show clearly that these reaction by-products do not inhibit the heterogeneous reaction step on SiO{sub 2} at 1,000K. FTIR was used to determine that ethoxy groups from TEOS dissociative chemisorption have a significant lifetime on the SiO{sub 2} surface at CVD temperatures and have an activation energy for decomposition of 16kcal/mol{+-}4kcal/mol. This is much higher than the activation energy of 6 kcal/mol reported for the initial chemisorption step and is near the 22 kcal/mol reported for the overall activation energy for SiO{sub 2} deposition in a cold-wall reactor. These results suggest that, whether or not surface ethoxy groups inhibit TEOS reactions, their decomposition may be directly related to the rate-limiting step in SiO{sub 2} deposition.

  4. Electronic properties of embedded graphene: doped amorphous silicon/CVD graphene heterostructures

    Science.gov (United States)

    Arezki, Hakim; Boutchich, Mohamed; Alamarguy, David; Madouri, Ali; Alvarez, José; Cabarrocas, Pere Roca i.; Kleider, Jean-Paul; Yao, Fei; Lee, Young Hee

    2016-10-01

    Large-area graphene film is of great interest for a wide spectrum of electronic applications, such as field effect devices, displays, and solar cells, among many others. Here, we fabricated heterostructures composed of graphene (Gr) grown by chemical vapor deposition (CVD) on copper substrate and transferred to SiO2/Si substrates, capped by n- or p-type doped amorphous silicon (a-Si:H) deposited by plasma-enhanced chemical vapor deposition. Using Raman scattering we show that despite the mechanical strain induced by the a-Si:H deposition, the structural integrity of the graphene is preserved. Moreover, Hall effect measurements directly on the embedded graphene show that the electronic properties of CVD graphene can be modulated according to the doping type of the a-Si:H as well as its phase i.e. amorphous or nanocrystalline. The sheet resistance varies from 360 Ω sq-1 to 1260 Ω sq-1 for the (p)-a-Si:H/Gr (n)-a-Si:H/Gr, respectively. We observed a temperature independent hole mobility of up to 1400 cm2 V-1 s-1 indicating that charge impurity is the principal mechanism limiting the transport in this heterostructure. We have demonstrated that embedding CVD graphene under a-Si:H is a viable route for large scale graphene based solar cells or display applications.

  5. Graphene-based structure, method of suspending graphene membrane, and method of depositing material onto graphene membrane

    Science.gov (United States)

    Zettl, Alexander K.; Meyer, Jannik Christian

    2013-04-02

    An embodiment of a method of suspending a graphene membrane across a gap in a support structure includes attaching graphene to a substrate. A pre-fabricated support structure having the gap is attached to the graphene. The graphene and the pre-fabricated support structure are then separated from the substrate which leaves the graphene membrane suspended across the gap in the pre-fabricated support structure. An embodiment of a method of depositing material includes placing a support structure having a graphene membrane suspended across a gap under vacuum. A precursor is adsorbed to a surface of the graphene membrane. A portion of the graphene membrane is exposed to a focused electron beam which deposits a material from the precursor onto the graphene membrane. An embodiment of a graphene-based structure includes a support structure having a gap, a graphene membrane suspended across the gap, and a material deposited in a pattern on the graphene membrane.

  6. Lipids, atherosclerosis and CVD risk: is CRP an innocent bystander?

    DEFF Research Database (Denmark)

    Nordestgaard, B G; Zacho, J

    2009-01-01

    exclude that genetically elevated CRP cause CVD. CONCLUSION: These data suggest that elevated CRP per se does not cause CVD; however, inflammation per se possibly contributes to CVD. Elevated CRP levels more likely is a marker for the extent of atherosclerosis or for the inflammatory activity...

  7. The Effect of Alumina and Magnesia Supported Germanium Nanoparticles on the Growth of Carbon Nanotubes in the Chemical Vapor Deposition Method

    Directory of Open Access Journals (Sweden)

    Ghazaleh Allaedini

    2015-01-01

    Full Text Available The effect of alumina and magnesia supported germanium (Ge nanoparticles on the synthesis of carbon nanotubes (CNTs using the chemical vapor deposition (CVD method in atmospheric pressure was investigated. The TEM micrographs confirmed the formation of carbon nanotubes, and the field emission scanning electron microscopy (FESEM analysis suggested a tip-growth mechanism for the grown carbon nanotubes. The X-ray diffraction (XRD pattern indicated a graphitic nature of the carbon nanotubes. The obtained CNTs using Ge nanoparticles supported by MgO resulted in a higher degree of graphitization than the CNTs obtained using Ge nanoparticles supported by Al2O3. Raman spectroscopy analysis of the CNTs confirmed the presence of radial breathing modes (RBM, which verified the formation of CNTs. High frequency Raman analysis demonstrated that the degree of graphitization of the synthesized CNTs using magnesia supported Ge nanoparticles is higher than that of the alumina supported Ge nanoparticles with the values of (ID/IG ratios equal to 0.45 and 0.73, respectively.

  8. Influence of surface morphology and microstructure on performance of CVD tungsten coating under fusion transient thermal loads

    Science.gov (United States)

    Lian, Youyun; Liu, Xiang; Wang, Jianbao; Feng, Fan; Lv, Yanwei; Song, Jiupeng; Chen, Jiming

    2016-12-01

    Thick tungsten coatings have been deposited by chemical vapor deposition (CVD) at a rapid growth rate. A series of tungsten coatings with different thickness and surface morphology were prepared. The surface morphology, microstructure and preferred orientation of the CVD tungsten coatings were investigated. Thermal shock analyses were performed by using an electron beam facility to study the influence of the surface morphology and the microstructure on the thermal shock resistance of the CVD tungsten coatings. Repetitive (100 pulses) ELMs-like thermal shock loads were applied at various temperatures between room temperature and 600 °C with pulse duration of 1 ms and an absorbed power density of up to 1 GW/m2. The results of the tests demonstrated that the specific surface morphology and columnar crystal structure of the CVD tungsten have significant influence on the surface cracking threshold and crack propagation of the materials. The CVD tungsten coatings with a polished surface show superior thermal shock resistance as compared with that of the as-deposited coatings with a rough surface.

  9. Dry deposition model for a microscale aerosol dispersion solver based on the moment method

    CERN Document Server

    Šíp, Viktor

    2016-01-01

    A dry deposition model suitable for use in the moment method has been developed. Contributions from five main processes driving the deposition - Brownian diffusion, interception, impaction, turbulent impaction, and sedimentation - are included in the model. The deposition model was employed in the moment method solver implemented in the OpenFOAM framework. Applicability of the developed expression and the moment method solver was tested on two example problems of particle dispersion in the presence of a vegetation on small scales: a flow through a tree patch in 2D and a flow through a hedgerow in 3D. Comparison with the sectional method showed that the moment method using the developed deposition model is able to reproduce the shape of the particle size distribution well. The relative difference in terms of the third moment of the distribution was below 10\\% in both tested cases, and decreased away from the vegetation. Main source of this difference is a known overprediction of the impaction efficiency. When ...

  10. PREPARING OF THE CHAMELEON COATING BY THE ION JET DEPOSITION METHOD

    Directory of Open Access Journals (Sweden)

    Jakub Skocdopole

    2017-07-01

    Full Text Available Preparation of chameleon coatings using an Ionized Jet Deposition (IJD technique is reported in the present paper. IJD is a new flexible method for thin film deposition developed by Noivion, Srl. The chameleon coatings are thin films characterised by a distinct change of their tribological properties according to the external conditions. The deposited films of SiC and TiN materials were examined by the Raman spectroscopy, SEM and XPS. The results of the Raman spectroscopy have proved an amorphous structure of SiC films. The data from XPS on TiN films have shown that the films are heavily oxidized, but also prove that the films are composed of TiN and pure Ti. The SEM provided information about the size of grains and particles constituting the deposited films, which is important for tribological properties of the films. Deposition of the chameleon coating is very complex problem and IJD could be ideal method for preparation of this coating.

  11. CVD technologies used in preparation of low dielectric constant CVD technologies used in preparation of low dielectric constant%ULSI低介电常数材料制备中的CVD技术

    Institute of Scientific and Technical Information of China (English)

    王鹏飞; 丁士进; 张卫; 王季陶; 李伟

    2001-01-01

    Various CVD technologies for preparing low dielectric constantmaterials in ULSI circuits are summarized. The processes of deposition of fluorinated silicon oxide thin films, fluorinated amorphous carbon thin films and polyimide films are discussed in detail. The APCVD and RTCVD methods applied to prepare parylene films and fluorinated silicon oxide thin films are also briefly imroduced.%综述了制备ULSI低介电常数材料的各种CVD技术。详细介绍PCVD技术淀积含氟氧化硅薄膜、含氟无定型碳膜与聚酰亚胺类薄膜的工艺,简要介绍了APCVD技术淀积聚对二甲苯类有机薄膜及RTCVD技术淀积SiOF薄膜的工艺。

  12. An indirect method to measure the electric charge deposited on insulators during PIXE analysis

    Energy Technology Data Exchange (ETDEWEB)

    Dinator, M.I.; Cancino, S.A.; Miranda, P.A. [Departamento de Fisica, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Nunoa, Santiago (Chile); Morales, J.R. [Departamento de Fisica, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Nunoa, Santiago (Chile)], E-mail: rmorales@uchile.cl; Seelenfreund, A. [Universidad Academia de Humanismo Cristiano, Condell 343, Providencia, Santiago (Chile)

    2007-10-15

    Total charge deposited by a proton beam in an insulator during PIXE analysis has been indirectly determined using a Mylar film coated with cobalt. Elemental concentrations in the samples, pieces of volcanic glass, were obtained and compared to concentrations determined by ICP OES on the same samples. The strong agreement between these results shows the accuracy of the charge determined by this method.

  13. Automated MALDI matrix deposition method with inkjet printing for imaging mass spectrometry.

    Science.gov (United States)

    Baluya, Dodge L; Garrett, Timothy J; Yost, Richard A

    2007-09-01

    Careful matrix deposition on tissue samples for matrix-assisted laser desorption/ionization (MALDI) is critical for producing reproducible analyte ion signals. Traditional methods for matrix deposition are often considered an art rather than a science, with significant sample-to-sample variability. Here we report an automated method for matrix deposition, employing a desktop inkjet printer (printer tray, designed to hold CDs and DVDs, was modified to hold microscope slides. Empty ink cartridges were filled with MALDI matrix solutions, including DHB in methanol/water (70:30) at concentrations up to 40 mg/mL. Various samples (including rat brain tissue sections and standards of small drug molecules) were prepared using three deposition methods (electrospray, airbrush, inkjet). A linear ion trap equipped with an intermediate-pressure MALDI source was used for analyses. Optical microscopic examination showed that matrix crystals were formed evenly across the sample. There was minimal background signal after storing the matrix in the cartridges over a 6-month period. Overall, the mass spectral images gathered from inkjet-printed tissue specimens were of better quality and more reproducible than from specimens prepared by the electrospray and airbrush methods.

  14. Deposition of titanium nitride layers by electric arc - Reactive plasma spraying method

    Energy Technology Data Exchange (ETDEWEB)

    Serban, Viorel-Aurel [University ' Politehnica' of Timisoara, Faculty of Mechanical Engineering, No. 1 Mihai Viteazu Boulevard, 300222 Timisoara (Romania); Rosu, Radu Alexandru, E-mail: raduniz@gmail.com [University ' Politehnica' of Timisoara, Faculty of Mechanical Engineering, No. 1 Mihai Viteazu Boulevard, 300222 Timisoara (Romania); Bucur, Alexandra Ioana [National Institute for Research and Development in Electrochemistry and Condensed Matter Timisoara, Analysis and Characterization Department, No. 1 P Andronescu Street, Timisoara 300224 (Romania); Pascu, Doru Romulus [Romania National Research and Development Institute for Welding and Material Testing Timisoara, No. 30 Mihai Viteazu Boulevard, 300222 Timisoara (Romania)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer Titanium nitride layers deposited by electric arc - reactive plasma spraying method. Black-Right-Pointing-Pointer Deposition of titanium nitride layers on C45 steel at different spraying distances. Black-Right-Pointing-Pointer Characterization of the coatings hardness as function of the spraying distances. Black-Right-Pointing-Pointer Determination of the corrosion behavior of titanium nitride layers obtained. - Abstract: Titanium nitride (TiN) is a ceramic material which possesses high mechanical properties, being often used in order to cover cutting tools, thus increasing their lifetime, and also for covering components which are working in corrosive environments. The paper presents the experimental results on deposition of titanium nitride coatings by a new combined method (reactive plasma spraying and electric arc thermal spraying). In this way the advantages of each method in part are combined, obtaining improved quality coatings in the same time achieving high productivity. Commercially pure titanium wire and C45 steel as substrate were used for experiments. X-ray diffraction analysis shows that the deposited coatings are composed of titanium nitride (TiN, Ti{sub 2}N) and small amounts of Ti{sub 3}O. The microstructure of the deposited layers, investigated both by optical and scanning electron microscopy, shows that the coatings are dense, compact, without cracks and with low porosity. Vickers microhardness of the coatings presents maximum values of 912 HV0.1. The corrosion tests in 3%NaCl solution show that the deposited layers have a high corrosion resistance compared to unalloyed steel substrate.

  15. Significance of vapor phase chemical reactions on CVD rates predicted by chemically frozen and local thermochemical equilibrium boundary layer theories

    Science.gov (United States)

    Gokoglu, Suleyman A.

    1988-01-01

    This paper investigates the role played by vapor-phase chemical reactions on CVD rates by comparing the results of two extreme theories developed to predict CVD mass transport rates in the absence of interfacial kinetic barrier: one based on chemically frozen boundary layer and the other based on local thermochemical equilibrium. Both theories consider laminar convective-diffusion boundary layers at high Reynolds numbers and include thermal (Soret) diffusion and variable property effects. As an example, Na2SO4 deposition was studied. It was found that gas phase reactions have no important role on Na2SO4 deposition rates and on the predictions of the theories. The implications of the predictions of the two theories to other CVD systems are discussed.

  16. Scanning Tunnelling Microscopy Observation on 10,12-Tricosadiynoic Acid Monolayers Deposited by Schaefer's Method

    Institute of Scientific and Technical Information of China (English)

    张耿民

    2001-01-01

    The Langmuir-Blodgett monolayers of 10, 12-tricosadiynoic acid molecules were deposited onto the basal plane of highly oriented pyrolytic graphite (HOPG) by Schaefer's method and then observed with the scanning tunnelling microscope (STM). With a view to achieving a parallel molecular arrangement on the graphite surface, the deposition was deliberately conducted at a relatively low surface pressure. As exhibited by the STM images, by this approach the 10,12-tricosadiynoic acid molecules could constitute an ordered structure with their molecular chains lying parallel to the substrate. The model of molecular dimer is put forward for the interpretation of the observed phenomena.

  17. From Bench Top to Market: Growth of Multi-Walled Carbon Nanotubes by Injection CVD Using Fe Organometallics - Production of a Commercial Reactor

    Science.gov (United States)

    Rowsell, J.; Hepp, A. F.; Harris, J. D.; Raffaelle, R. P.; Cowen, J. C.; Scheiman, D. A.; Flood, D. M.; Flood, D. J.

    2009-01-01

    Preferential oriented multiwalled carbon nanotubes were prepared by the injection chemical vapor deposition (CVD) method using either cyclopentadienyliron dicarbonyl dimer or cyclooctatetraene iron tricarbonyl as the iron catalyst source. The catalyst precursors were dissolved in toluene as the carrier solvent for the injections. The concentration of the catalyst was found to influence both the growth (i.e., MWNT orientation) of the nanotubes, as well as the amount of iron in the deposited material. As deposited, the multiwalled carbon nanotubes contained as little as 2.8% iron by weight. The material was deposited onto tantalum foil and fused silica substrates. The nanotubes were characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy and thermogravimetric analysis. This synthetic route provides a simple and scalable method to deposit MWNTs with a low defect density, low metal content and a preferred orientation. Subsequently, a small start-up was founded to commercialize the deposition equipment. The contrast between the research and entrepreneurial environments will be discussed.

  18. Nanocrystalline sp 2 and sp 3 carbons: CVD synthesis and applications

    Science.gov (United States)

    Terranova, M. L.; Rossi, M.; Tamburri, E.

    2016-11-01

    The design and production of innovative materials based on nanocrystalline sp 2- and sp 3-coordinated carbons is presently a focus of the scientific community. We present a review of the nanostructures obtained in our labs using a series of synthetic routes, which make use of chemical vapor deposition (CVD) techniques for the selective production of non-planar graphitic nanostructures, nanocrystalline diamonds, and hybrid two-phase nanostructures.

  19. Tribological Testing of Some Potential PVD and CVD Coatings for Steel Wire Drawing Dies

    OpenAIRE

    Nilsson, Maria; Olsson, Mikael

    2010-01-01

    Cemented carbide is today the most frequently used drawing die material in steel wire drawing applications. This is mainly due to the possibility to obtain a broad combination of hardness and toughness thus meeting the requirements concerning strength, crack resistance and wear resistance set by the wire drawing process. However, the increasing cost of cemented carbide in combination with the possibility to increase the wear resistance of steel through the deposition of wear resistant CVD and...

  20. Comparison of Straight and Helical Nanotube Production in a Swirled Fluid CVD Reactor

    OpenAIRE

    Bathgate, Graham; Iyuke, Sunny; Kavishe, Frank

    2012-01-01

    Research into Carbon Nanotubes and their applications is fast becoming an extremely popular topic, and any means to greatly improve the synthesis process has a huge marketability. While investigating the feasibility of continuous production of single-walled carbon nanotubes in a vertical Swirled Fluid Chemical Vapour Deposition (CVD) reactor, it was discovered that helical nanotubes were lifted from the reactor by the gas current while straight tubes remained behind. Investigation into the me...

  1. Using different chemical methods for deposition of copper selenide thin films and comparison of their characterization.

    Science.gov (United States)

    Güzeldir, Betül; Sağlam, Mustafa

    2015-11-05

    Different chemical methods such as Successive Ionic Layer Adsorption and Reaction (SILAR), spin coating and spray pyrolysis methods were used to deposite of copper selenide thin films on the glass substrates. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray analysis (EDX) spectroscopy and UV-vis spectrophotometry. The XRD and SEM studies showed that all the films exhibit polycrystalline nature and crystallinity of copper selenide thin films prepared with spray pyrolysis greater than spin coating and SILAR methods. From SEM and AFM images, it was observed copper selenide films were uniform on the glass substrates without any visible cracks or pores. The EDX spectra showed that the expected elements exist in the thin films. Optical absorption studies showed that the band gaps of copper selenide thin films were in the range 2.84-2.93 eV depending on different chemical methods. The refractive index (n), optical static and high frequency dielectric constants (ε0, ε∞) values were calculated by using the energy bandgap values for each deposition method. The obtained results from different chemical methods revealed that the spray pyrolysis technique is the best chemical deposition method to fabricate copper selenide thin films. This absolute advantage was lead to play key roles on performance and efficiency electrochromic and photovoltaic devices.

  2. A simple method for the deposition of nanostructured tellurium synthesized in ammonia solution

    Directory of Open Access Journals (Sweden)

    C. D. Gutiérrez-Lazos

    2016-02-01

    Full Text Available Abstract In this work, we report a highly adherent, and uniform deposition of nanostructured tellurium. The deposition of the nanostructured tellurium was realized by the dripping of a modified solution of NaHTe based on the dissolution of NaBH4 and tellurium powder in an aqueous solution of NH4OH. This method allowed the relatively simple manipulation of tellurium nanostructures under laboratory ambient, without requiring the use of organic stabilizers. Transmission electron microscopy (TEM was realized on a powder sample obtained by the reaction between H2Te and aqueous solution of NH4OH. TEM analysis indicated that tellurium nanorods and Y-type nanostructures are grown from tellurium nanoparticles, such as in a hydrothermal system. Then, the nanoparticles serve as seeds for the growth of more extended tellurium nanostructures. Electron diffraction and X-ray diffraction analysis showed that depositions have the hexagonal structure of tellurium highly oriented on (101 direction.

  3. Discrete formulation of mixed finite element methods for vapor deposition chemical reaction equations

    Institute of Scientific and Technical Information of China (English)

    LUO Zhen-dong; ZHOU Yan-jie; ZHU Jiang

    2007-01-01

    The vapor deposition chemical reaction processes, which are of extremely extensive applications, can be classified as a mathematical modes by the following governing nonlinear partial differential equations containing velocity vector,temperature field,pressure field,and gas mass field.The mixed finite element(MFE)method is employed to study the system of equations for the vapor deposition chemical reaction processes.The semidiscrete and fully discrete MFE formulations are derived.And the existence and convergence(error estimate)of the semidiscrete and fully discrete MFE solutions are deposition chemical reaction processes,the numerical solutions of the velocity vector,the temperature field,the pressure field,and the gas mass field can be found out simultaneonsly.Thus,these researches are not only of important theoretical means,but also of extremely extensive applied vistas.

  4. Influence of bias on properties of carbon films deposited by MCECR plasma sputtering method

    Institute of Scientific and Technical Information of China (English)

    CAI Chang-long; DIAO Dong-feng; S.Miyake; T.Matsumoto

    2004-01-01

    The mirror-confinement-type electron cyclotron resonance(MCECR) plasma source has high plasma density and high electron temperature. It is quite useful in many plasma processing, and has been used for etching and thin-film deposition. The carbon films with 40 nm thickness were deposited by MCECR plasma sputtering method on Si, and the influence of substrate bias on the properties of carbon films was studied. The bonding structure of the film was analyzed by the X-ray photoelectron spectroscopy(XPS), the tribological properties were measured by the pin-on-disk(POD) tribometer, the nanohardness of the films was measured by the nanoindenter, and the deposition speed and the refractive index were measured by the ellipse meter. The better substrate bias was obtained, and the better properties of carbon films were obtained.

  5. Method development estimating ambient mercury concentration from monitored mercury wet deposition

    Directory of Open Access Journals (Sweden)

    S. M. Chen

    2013-05-01

    Full Text Available Speciated atmospheric mercury data have recently been monitored at multiple locations in North America; but the spatial coverage is far less than the long-established mercury wet deposition network. The present study describes a first attempt linking ambient concentration with wet deposition using Beta distribution fitting of a ratio estimate. The mean, median, mode, standard deviation, and skewness of the fitted Beta distribution parameters were generated using data collected in 2009 at 11 monitoring stations. Comparing the normalized histogram and the fitted density function, the empirical and fitted Beta distribution of the ratio shows a close fit. The estimated ambient mercury concentration was further partitioned into reactive gaseous mercury and particulate bound mercury using linear regression model developed by Amos et al. (2012. The method presented here can be used to roughly estimate mercury ambient concentration at locations and/or times where such measurement is not available but where wet deposition is monitored.

  6. Application of microdosimetric methods for the determination of energy deposition distributions by inhaled actinides

    Energy Technology Data Exchange (ETDEWEB)

    Aubineau-Laniece, I.; Castellan, G.; Caswell, R.S.; Guezingar, F.; Henge-Napoli, M.H.; Li, W.B.; Pihet, P

    1998-07-01

    The respiratory tract dosimetry model of ICRP Publication 66 takes into account the morphometry of lung tissues for the determination of average energy deposited by {alpha} emitters. However, it assumes a uniform distribution of radioactive material. The statistical fluctuations in frequency of cells hit and of energy deposited in individual target cells depends significantly on the real distribution of radioactive material, including possible high local concentrations. This paper is aimed at investigating the application of two established analytic methods, which have been combined to determine single and multi-event energy deposition distributions in epithelial cells of bronchiolar airway exposed to 5.15 MeV {alpha} particles ({sup 239}Pu). The relative importance of multi-event occurrence on the shape of the specific energy distributions is discussed. (author)

  7. Post-deposition cooling in oxygen is critical for YBa sub 2 Cu sub 3 O sub 7 sub - sub d films deposited by eclipse pulsed laser deposition method

    CERN Document Server

    Ohmukai, M; Ohno, T

    2001-01-01

    YBa sub 2 Cu sub 3 O sub 7 sub - sub d thin films were deposited on MgO single crystals by means of an eclipse pulsed laser deposition method. Deposited films are cooled down in situ under an oxygen atmosphere at a given oxygen pressure. The relationship between critical temperature and oxygen deficiency was investigated by means of electrical resistance R(T) and X-ray diffraction measurements. Post- deposition cooling is critical and the high pressure of oxygen during cooling is favorable.

  8. Fabrication of ordered bulk heterojunction organic photovoltaic cells using nanopatterning and electrohydrodynamic spray deposition methods.

    Science.gov (United States)

    Park, Sung-Eun; Kim, Sehwan; Kim, Kangmin; Joe, Hang-Eun; Jung, Buyoung; Kim, Eunkyoung; Kim, Woochul; Min, Byung-Kwon; Hwang, Jungho

    2012-12-21

    Organic photovoltaic cells with an ordered heterojunction (OHJ) active layer are expected to show increased performance. In the study described here, OHJ cells were fabricated using a combination of nanoimprinting and electrohydrodynamic (EHD) spray deposition methods. After an electron donor material was nanoimprinted with a PDMS stamp (valley width: 230 nm, period: 590 nm) duplicated from a Si nanomold, an electron acceptor material was deposited onto the nanoimprinted donor layer using an EHD spray deposition method. The donor-acceptor interface layer was observed by obtaining cross-sectional images with a focused ion beam (FIB) microscope. The photocurrent generation performance of the OHJ cells was evaluated with the current density-voltage curve under air mass (AM) 1.5 conditions. It was found that the surface morphology of the electron acceptor layer affected the current and voltage outputs of the photovoltaic cells. When an electron acceptor layer with a smooth thin (250 nm above the valley of the electron donor layer) surface morphology was obtained, power conversion efficiency was as high as 0.55%. The electrohydrodynamic spray deposition method used to produce OHJ photovoltaic cells provides a means for the adoption of large area, high throughput processes.

  9. Structural, Optical and Electrical Properties of Nanocrystalline Cuprous Oxide Thin Film Deposited By Chemical Method

    Directory of Open Access Journals (Sweden)

    Prakash Bansilal Ahirrao

    2010-06-01

    Full Text Available Cuprous oxide (Cu2O is an interesting p-type semiconductor material used in solar cell applications.  The Modified Chemical Bath Deposition (M-CBD method is suitable for growing thin multilayer structure due to low deposition temperature. This method does not require any sophisticated instrument and substrate need not to be conductive. The nanocrystalline Cu2O thin films were deposited on glass substrates by M-CBD method. The deposited films were characterized by different characterization techniques to study structural, surface morphological, optical and electrical properties. The structural studies show that, the formation of Cu2O thin films with an average crystallite size of 14 nm. Optical studies show a direct band gap 2.48 eV. The room temperature electrical resistivity is of the order of 1.3 kW-cm and activation energy 0.33 eV. The films exhibit p-type electrical conductivity as seen by thermo-emf measurements.

  10. Initiated chemical vapor deposition of antimicrobial polymer coatings.

    Science.gov (United States)

    Martin, T P; Kooi, S E; Chang, S H; Sedransk, K L; Gleason, K K

    2007-02-01

    The vapor phase deposition of polymeric antimicrobial coatings is reported. Initiated chemical vapor deposition (iCVD), a solventless low-temperature process, is used to form thin films of polymers on fragile substrates. For this work, finished nylon fabric is coated by iCVD with no affect on the color or feel of the fabric. Infrared characterization confirms the polymer structure. Coatings of poly(dimethylaminomethyl styrene) of up to 540 microg/cm2 were deposited on the fabric. The antimicrobial properties were tested using standard method ASTM E2149-01. A coating of 40 microg/cm2 of fabric was found to be very effective against gram-negative Escherichia coli, with over a 99.99%, or 4 log, kill in just 2 min continuing to over a 99.9999%, or 6 log, reduction in viable bacteria in 60 min. A coating of 120 microg/cm2 was most effective against the gram-positive Bacillus subtilis. Further tests confirmed that the iCVD polymer did not leach off the fabric.

  11. The role of NH3 and hydrocarbon mixtures in GaN pseudo-halide CVD: a quantum chemical study.

    Science.gov (United States)

    Gadzhiev, Oleg B; Sennikov, Peter G; Petrov, Alexander I; Kachel, Krzysztof; Golka, Sebastian; Gogova, Daniela; Siche, Dietmar

    2014-11-01

    The prospects of a control for a novel gallium nitride pseudo-halide vapor phase epitaxy (PHVPE) with HCN were thoroughly analyzed for hydrocarbons-NH3-Ga gas phase on the basis of quantum chemical investigation with DFT (B3LYP, B3LYP with D3 empirical correction on dispersion interaction) and ab-initio (CASSCF, coupled clusters, and multireference configuration interaction including MRCI+Q) methods. The computational screening of reactions for different hydrocarbons (CH4, C2H6, C3H8, C2H4, and C2H2) as readily available carbon precursors for HCN formation, potential chemical transport agents, and for controlled carbon doping of deposited GaN was carried out with the B3LYP method in conjunction with basis sets up to aug-cc-pVTZ. The gas phase intermediates for the reactions in the Ga-hydrocarbon systems were predicted at different theory levels. The located π-complexes Ga…C2H2 and Ga…C2H4 were studied to determine a probable catalytic activity in reactions with NH3. A limited influence of the carbon-containing atmosphere was exhibited for the carbon doping of GaN crystal in the conventional GaN chemical vapor deposition (CVD) process with hydrocarbons injected in the gas phase. Our results provide a basis for experimental studies of GaN crystal growth with C2H4 and C2H2 as auxiliary carbon reagents for the Ga-NH3 and Ga-C-NH3 CVD systems and prerequisites for reactor design to enhance and control the PHVPE process through the HCN synthesis.

  12. Study of preparation of BG/HA gradient coating on titanium alloy by electrophoretic deposition method

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiao-ming; HAN Qing-rong; LI Shi-pu; XU Chuan-bo

    2001-01-01

    In this paper, a gradient bioactive coating made from modified bioglass (BG) and hydroxyapatite (HA) was prepared by electrophoretic deposition method(EPD)on the surface of titanium alloy. Strong bonding between the matrix and BG/HA gradient coating was got by sintering. Crystal composition of the coating was analyzed by XRD. The characteristics of surface and cross section of the coating were observed by SEM. Adhesive strength of the coating was tested by pull method. The optimizing technological parameters were determined.

  13. Deposition of tantalum carbide coatings on graphite by laser interactions

    Science.gov (United States)

    Veligdan, James; Branch, D.; Vanier, P. E.; Barietta, R. E.

    1994-01-01

    Graphite surfaces can be hardened and protected from erosion by hydrogen at high temperatures by refractory metal carbide coatings, which are usually prepared by chemical vapor deposition (CVD) or chemical vapor reaction (CVR) methods. These techniques rely on heating the substrate to a temperature where a volatile metal halide decomposes and reacts with either a hydrocarbon gas or with carbon from the substrate. For CVR techniques, deposition temperatures must be in excess of 2000 C in order to achieve favorable deposition kinetics. In an effort to lower the bulk substrate deposition temperature, the use of laser interactions with both the substrate and the metal halide deposition gas has been employed. Initial testing involved the use of a CO2 laser to heat the surface of a graphite substrate and a KrF excimer laser to accomplish a photodecomposition of TaCl5 gas near the substrate. The results of preliminary experiments using these techniques are described.

  14. Corrosion protection of SiC-based ceramics with CVD mullite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Sarin, V.; Mulpuri, R.; Auger, M. [Boston University, Boston, MA (United States) Manufacturing Engineering

    1996-04-20

    SiC based ceramics have been identified as the leading candidate materials for elevated temperature applications in harsh oxidation/corrosion environments. It has been established that a protective coating can be effectively used to avoid problems with excessive oxidation and hot corrosion. However, to date, no coating configuration has been developed that can withstand the rigorous requirements imposed by such applications. Chemical vapor deposited (CVD) mullite coatings due to their desirable properties of toughness, corrosion resistance, and good coefficient of thermal expansion match with SiC are being developed as a potential solution. Formation of mullite on ceramic substrates via chemical vapor deposition was investigated. Thermodynamic calculations performed on the AlCl{sub 3}- SiCl{sub 4}-CO{sub 2}-H{sub 2} system were used to construct equilibrium CVD phase diagrams. Through process optimization, crystalline CVD mullite coatings have been successfully grown on SiC and Si{sub 3}N{sub 4} substrates. Results from the thermodynamic analysis, process optimization, and effect of various process parameters on deposition rate and coating morphology are discussed.

  15. Deposition of metal chalcogenide thin films by successive ionic layer adsorption and reaction (SILAR) method

    Indian Academy of Sciences (India)

    H M Pathan; C D Lokhande

    2004-04-01

    During last three decades, successive ionic layer adsorption and reaction (SILAR) method, has emerged as one of the solution methods to deposit a variety of compound materials in thin film form. The SILAR method is inexpensive, simple and convenient for large area deposition. A variety of substrates such as insulators, semiconductors, metals and temperature sensitive substrates (like polyester) can be used since the deposition is carried out at or near to room temperature. As a low temperature process, it also avoids oxidation and corrosion of the substrate. The prime requisite for obtaining good quality thin film is the optimization of preparative provisos viz. concentration of the precursors, nature of complexing agent, pH of the precursor solutions and adsorption, reaction and rinsing time durations etc. In the present review article, we have described in detail, successive ionic layer adsorption and reaction (SILAR) method of metal chalcogenide thin films. An extensive survey of thin film materials prepared during past years is made to demonstrate the versatility of SILAR method. Their preparative parameters and structural, optical, electrical properties etc are described. Theoretical background necessary for the SILAR method is also discussed.

  16. A modified micrometeorological gradient method for estimating O3 dry deposition over a forest canopy

    Directory of Open Access Journals (Sweden)

    Z. Y. Wu

    2015-01-01

    Full Text Available Small pollutant concentration gradients between levels above a plant canopy result in large uncertainties in estimated air–surface exchange fluxes when using existing micrometeorological gradient methods, including the aerodynamic gradient method (AGM and the modified Bowen-Ratio method (MBR. A modified micrometeorological gradient method (MGM is proposed in this study for estimating O3 dry deposition fluxes over a forest canopy using concentration gradients between a level above and a level below the canopy top, taking advantage of relatively large gradients between these levels due to significant pollutant uptake at top layers of the canopy. The new method is compared with the AGM and MBR methods and is also evaluated using eddy-covariance (EC flux measurements collected at the Harvard Forest Environmental Measurement Site, Massachusetts during 1993–2000. All the three gradient methods (AGM, MBR and MGM produced similar diurnal cycles of O3 dry deposition velocity (Vd(O3 to the EC measurements, with the MGM method being the closest in magnitude to the EC measurements. The multi-year average Vd(O3 differed significantly between these methods, with the AGM, MBR and MGM method being 2.28, 1.45 and 1.18 times of that of the EC. Sensitivity experiments identified several input parameters for the MGM method as first-order parameters that affect the estimated Vd(O3. A 10% uncertainty in the wind speed attenuation coefficient or canopy displacement height can cause about 10% uncertainty in the estimated Vd(O3. An unrealistic leaf area density vertical profile can cause an uncertainty of a factor of 2.0 in the estimated Vd(O3. Other input parameters or formulas for stability functions only caused an uncertainly of a few percent. The new method provides an alternative approach in monitoring/estimating long-term deposition fluxes of similar pollutants over tall canopies.

  17. Catalyst Design Using Nanoporous Iron for the Chemical Vapor Deposition Synthesis of Single-Walled Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Tarek M. Abdel-Fattah

    2013-01-01

    Full Text Available Single-walled carbon nanotubes (SWNTs have been synthesized via a novel chemical vapor deposition (CVD approach utilizing nanoporous, iron-supported catalysts. Stable aqueous dispersions of the CVD-grown nanotubes using an anionic surfactant were also obtained. The properties of the as-produced SWNTs were characterized through atomic force microscopy and Raman spectroscopy and compared with purified SWNTs produced via the high-pressure CO (HiPCO method as a reference, and the nanotubes were observed with greater lengths than those of similarly processed HiPCO SWNTs.

  18. Fabrication and characterization of kesterite Cu2ZnSnS4 thin films deposited by electrostatic spray assisted vapour deposition method

    OpenAIRE

    Liu, J. P.; Choy, Kwang-Leong; Placidi, M.; López-García, J.; Saucedo, Edgardo; Colombara, Diego; Robert, Erika

    2014-01-01

    Most of the high efficiency kesterite solar cells are fabricated by vacuum or hydrazine-based solution methods which have drawbacks, such as high cost, high toxicity or explosivity. In our contribution, an alternative non-vacuum and environmental friendly deposition technology called electrostatic spray assisted vapour deposition (ESAVD) has been used for the cost-effective growth of Cu2ZnSnS4 (CZTS) thin films with well controlled structure and composition. CZTS films have been characterized...

  19. Q-factors of CVD monolayer graphene and graphite inductors

    Science.gov (United States)

    Wang, Zidong; Zhang, Qingping; Peng, Pei; Tian, Zhongzheng; Ren, Liming; Zhang, Xing; Huang, Ru; Wen, Jincai; Fu, Yunyi

    2017-08-01

    A carbon-based inductor may serve as an important passive component in a carbon-based radio-frequency (RF) integrated circuit (IC). In this work, chemical vapor deposition (CVD) synthesized monolayer graphene and graphite inductors are fabricated and their Q-factors are investigated. We find that the large series resistance of signal path (including coil resistance and contact resistance) in monolayer graphene inductors causes negative Q-factors at the whole frequency range in measurement. Comparatively, some of the graphite inductors have all of their Q-factors above zero, due to their small signal path resistance. We also note that some other graphite inductors have negative Q-factor values at low frequency regions, but positive Q-factor values at high frequency regions. With an equivalent circuit model, we confirm that the negative Q-factors of some graphite inductors at low frequency regions are related to their relatively large contact resistances, and we are able to eliminate these negative Q-factors by improving the graphite-metal contact. Furthermore, the peak Q-factor (Q p) can be enhanced by lowering down the resistance of graphite coil. For an optimized 3/4-turn graphite inductor, the measured maximum Q-factor (Q m) can reach 2.36 and the peak Q-factor is theoretically predicted by the equivalent circuit to be as high as 6.46 at a high resonant frequency, which is beyond the testing frequency range. This research indicates that CVD synthesized graphite thin film is more suitable than graphene for fabricating inductors in carbon-based RF IC in the future.

  20. Deposition of titanium nitride layers by electric arc - Reactive plasma spraying method

    Science.gov (United States)

    Şerban, Viorel-Aurel; Roşu, Radu Alexandru; Bucur, Alexandra Ioana; Pascu, Doru Romulus

    2013-01-01

    Titanium nitride (TiN) is a ceramic material which possesses high mechanical properties, being often used in order to cover cutting tools, thus increasing their lifetime, and also for covering components which are working in corrosive environments. The paper presents the experimental results on deposition of titanium nitride coatings by a new combined method (reactive plasma spraying and electric arc thermal spraying). In this way the advantages of each method in part are combined, obtaining improved quality coatings in the same time achieving high productivity. Commercially pure titanium wire and C45 steel as substrate were used for experiments. X-ray diffraction analysis shows that the deposited coatings are composed of titanium nitride (TiN, Ti2N) and small amounts of Ti3O. The microstructure of the deposited layers, investigated both by optical and scanning electron microscopy, shows that the coatings are dense, compact, without cracks and with low porosity. Vickers microhardness of the coatings presents maximum values of 912 HV0.1. The corrosion tests in 3%NaCl solution show that the deposited layers have a high corrosion resistance compared to unalloyed steel substrate.

  1. Application of the Taguchi method to the analysis of the deposition step in microarray production.

    Science.gov (United States)

    Severgnini, Marco; Pattini, Linda; Consolandi, Clarissa; Rizzi, Ermanno; Battaglia, Cristina; De Bellis, Gianluca; Cerutti, Sergio

    2006-09-01

    Every microarray experiment is affected by many possible sources of variability that may even corrupt biological evidence on analyzed sequences. We applied a "Taguchi method" strategy, based on the use of orthogonal arrays to optimize the deposition step of oligonucleotide sequences on glass slides. We chose three critical deposition parameters (humidity, surface, and buffer) at two levels each, in order to establish optimum settings. A L8 orthogonal array was used in order to monitor both the main effects and interactions on the deposition of a 25 mer oligonucleotide hybridized to its fluorescent-labeled complementary. Signal-background ratio and deposition homogeneity in terms of mean intensity and spot diameter were considered as significant outputs. An analysis of variance (ANOVA) was applied to raw data and to mean results for each slide and experimental run. Finally we calculated an overall evaluation coefficient to group together important outputs in one number. Environmental humidity and surface-buffer interaction were recognized as the most critical factors, for which a 50% humidity, associated to a chitosan-covered slide and a sodium phosphate + 25% dimethyl sulfoxide (DMSO) buffer gave best performances. Our results also suggested that Taguchi methods can be efficiently applied in optimization of microarray procedures.

  2. Lateral gas phase diffusion length of boron atoms over Si/B surfaces during CVD of pure boron layers

    NARCIS (Netherlands)

    Mohammadi, V.; Nihtianov, S.

    2016-01-01

    The lateral gas phase diffusion length of boron atoms, LB, along silicon and boron surfaces during chemical vapor deposition(CVD) using diborane (B2H6) is reported. The value of LB is critical for reliable and uniform boron layer coverage. The presented information was obtained experimentally and co

  3. Lateral gas phase diffusion length of boron atoms over Si/B surfaces during CVD of pure boron layers

    NARCIS (Netherlands)

    Mohammadi, V.; Nihtianov, S.

    2016-01-01

    The lateral gas phase diffusion length of boron atoms, LB, along silicon and boron surfaces during chemical vapor deposition(CVD) using diborane (B2H6) is reported. The value of LB is critical for reliable and uniform boron layer coverage. The presented information was obtained experimentally and co

  4. Effect of mixture ratios and nitrogen carrier gas flow rates on the morphology of carbon nanotube structures grown by CVD

    CSIR Research Space (South Africa)

    Malgas, GF

    2008-02-01

    Full Text Available This paper reports on the growth of carbon nanotubes (CNTs) by thermal Chemical Vapour Deposition (CVD) and investigates the effects of nitrogen carrier gas flow rates and mixture ratios on the morphology of CNTs on a silicon substrate by vaporizing...

  5. The conductivity of high-fluence noble gas ion irradiated CVD polycrystalline diamond

    Science.gov (United States)

    Borisov, A. M.; Kazakov, V. A.; Mashkova, E. S.; Ovchinnikov, M. A.; Shemukhin, A. A.; Sigalaev, S. K.

    2017-09-01

    The conductivity of surface layer of polycrystalline CVD (Chemical Vapor Deposition) diamond has been studied experimentally after high-fluence 30 keV Ne+, 20 and 30 keV Ar+ ion irradiation at target temperature range from 30 to 400 °C. The hot ion irradiation of CVD diamond may be described as ion-stimulated heat graphitization in which an exponential resistance decrease with increasing of the irradiation temperature is much faster than at the heat treatment. Under ion irradiation of CVD diamond the graphite-like materials resistivity is achieved at temperatures not exceeding 200 °C. The graphite phase in a heterogeneous structure of diamond irradiated layer is in dynamic equilibrium. In the temperature range from RT to 400 °C, the proportion of graphite phase increases so that at temperatures 200 < Tir < 400 °C it is dominant. The Raman spectra of ion-induced conductive layer created on CVD diamond reflect the processes of nanostructural ordering - disordering of sp2-bonded carbon.

  6. Method of monitoring photoactive organic molecules in-situ during gas-phase deposition of the photoactive organic molecules

    Science.gov (United States)

    Forrest, Stephen R.; Vartanian, Garen; Rolin, Cedric

    2015-06-23

    A method for in-situ monitoring of gas-phase photoactive organic molecules in real time while depositing a film of the photoactive organic molecules on a substrate in a processing chamber for depositing the film includes irradiating the gas-phase photoactive organic molecules in the processing chamber with a radiation from a radiation source in-situ while depositing the film of the one or more organic materials and measuring the intensity of the resulting photoluminescence emission from the organic material. One or more processing parameters associated with the deposition process can be determined from the photoluminescence intensity data in real time providing useful feedback on the deposition process.

  7. CVD elaboration of nanostructured TiO2-Ag thin films with efficient antibacterial properties

    OpenAIRE

    Mungkalasiri, Jitti; Bedel, Laurent; Emieux, Fabrice; Dore, Jeanne; Renaud, François N. R.; Sarantopoulos, Christos; Maury, Francis

    2010-01-01

    Nanostructured TiO2-Ag composite coatings are deposited by direct liquid injection metal-organic (DLI-MO) CVD at 683K in a one-step process. Silver pivalate (AgPiv) and titanium tetra-iso-propoxide (TTIP) are used as Ag and Ti molecular precursors, respectively. Metallic silver nanoparticles are co-deposited with anatase TiO2 on stainless steel, glass, and silicon wafers. The silver particles are uniformly embedded in the oxide matrix through the entire film thickness. The influence of the gr...

  8. Method to control deposition rate instabilities—High power impulse magnetron sputtering deposition of TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Kossoy, Anna, E-mail: annaeden@hi.is, E-mail: anna.kossoy@gmail.com; Magnusson, Rögnvaldur L.; Tryggvason, Tryggvi K.; Leosson, Kristjan; Olafsson, Sveinn [Physics Division, Science Institute—University of Iceland, Reykjavik 107 (Iceland)

    2015-03-15

    The authors describe how changes in shutter state (open/closed) affect sputter plasma conditions and stability of the deposition rate of Ti and TiO{sub 2} films. The films were grown by high power impulse magnetron sputtering in pure Ar and in Ar/O{sub 2} mixture from a metallic Ti target. The shutter state was found to have an effect on the pulse waveform for both pure Ar and reactive sputtering of Ti also affecting stability of TiO{sub 2} deposition rate. When the shutter opened, the shape of pulse current changed from rectangular to peak-plateau and pulse energy decreased. The authors attribute it to the change in plasma impedance and gas rarefaction originating in geometry change in front of the magnetron. TiO{sub 2} deposition rate was initially found to be high, 1.45 Å/s, and then dropped by ∼40% during the first 5 min, while for Ti the change was less obvious. Instability of deposition rate poses significant challenge for growing multilayer heterostructures. In this work, the authors suggest a way to overcome this by monitoring the integrated average energy involved in the deposition process. It is possible to calibrate and control the film thickness by monitoring the integrated pulse energy and end growth when desired integrated pulse energy level has been reached.

  9. Dating sediment deposits on Montalvanian carvings using EPR and TL methods

    Energy Technology Data Exchange (ETDEWEB)

    Sastry, M.D.; Sullasi, Henry S.L. E-mail: hsullasi@dfn.if.usp.br; Camargo, Fabiola; Watanabe, Shigueo; Prous, Andre P.P.; Silva, Martha M.C

    2004-01-01

    About 30 years ago a rock shelter with engravings by early settlers was found at Montalvania, northern end of state of Minas Gerais, Brazil. Lower part of engravings was covered with thin deposit of calcite mixed with quartz grains, due to occasional flood. This mixture of two minerals was dated by thermoluminescence and electron paramagnetic resonance using in both cases, additive method. The accumulated dose D{sub AC}, that is, natural radioactivity and cosmic rays radiation dose that induces TL and EPR signal intensity has been found to be around 50 Gy both by TL and EPR methods. The annual radiation dose rate was estimated to be about 1.027 mGy/a from knowledge of uranium, thorium and potassium content determined by inductively coupled plasma-mass spectrometer system. The age of this calcite plus quartz deposits was estimated to be about 50 ka.

  10. Methods of electrophoretic deposition for functionally graded porous nanostructures and systems thereof

    Energy Technology Data Exchange (ETDEWEB)

    Worsley, Marcus A; Baumann, Theodore F; Satcher, Joe H; Olson, Tammy Y; Kuntz, Joshua D; Rose, Klint A

    2015-03-03

    In one embodiment, an aerogel includes a layer of shaped particles having a particle packing density gradient in a thickness direction of the layer, wherein the shaped particles are characterized by being formed in an electrophoretic deposition (EPD) process using an impurity. In another embodiment, a method for forming a functionally graded porous nanostructure includes adding particles of an impurity and a solution to an EPD chamber, applying a voltage difference across the two electrodes of the EPD chamber to create an electric field in the EPD chamber, and depositing the material onto surfaces of the particles of the impurity to form shaped particles of the material. Other functionally graded materials and methods are described according to more embodiments.

  11. Synthesis and optical properties of ZnO nanocluster porous films deposited by modified SILAR method

    Science.gov (United States)

    Gao, X. D.; Li, X. M.; Yu, W. D.

    2004-05-01

    Ultrasonic rinsing procedure was introduced to successive ionic layer adsorption and reaction (SILAR) method. ZnO nanocluster porous films were successfully deposited on glass substrate using zinc-ammonia complexed precursor. The crystallinity, microstructure, optical properties and photoluminescence were measured and analyzed for both as-deposited and annealed films. Effects of experimental parameters and heat treatment on the structural and optical properties were discussed. Results show that as-deposited ZnO film exhibits excellent crystallinity with the preferential orientation of (0 0 2) plane. A porous feature with interconnected particles of 200-400 nm in ZnO films was observed, with each ZnO particle formed by the aggregation of many crystallites in size of 30-50 nm. The low transmittance due to scattering losses over the porous ZnO layer down to 16% was detected. The annealing at 400 °C can promote the preferential orientation along (1 0 0) plane, the interfusion of adjacent particles and the reduction of scattering loss. Intense and sharp ultraviolet emission peaks at 392 nm dominates the PL spectra for both as-deposited and annealed samples, indicating the good optical quality of ZnO layer.

  12. Application of Taguchi method for the characterization of calcareous deposits formed by pulse cathodic protection

    Energy Technology Data Exchange (ETDEWEB)

    Zamanzade, M.; Shahrabi, T. [Department of Materials Science and Engineering, Faculty of Engineering, Tarbiat Modares University, Tehran (Iran); Gharacheh, E.A. [Department of Industrial Engineering, Faculty of Engineering, Tarbiat Modares University, Tehran (Iran)

    2007-09-15

    In this study, the Taguchi method, a powerful tool to design optimization for quality, is used to find the optimal process parameters of pulse cathodic protection system for the calcareous deposits' formation. An orthogonal array, main effect and the signal-to-noise (S/N) ratio are employed to investigate the process parameters in order to achieve optimum final current density. Through this study also the main process parameters that affect the calcareous deposits' formation can be found. Experiments were carried out to confirm the effectiveness of this approach. From the results, chronoamperometric measurements have been used to evaluate the influence of pulse cathodic protection on decreasing the required cathodic current for protection and also decreasing the surface coverage. The morphology of the formed deposits has been evaluated through scanning electron microscopy (SEM) and chemical analysis of the formed deposits has been performed using X-ray diffraction (XRD). It is found that the different environmental conditions, i.e., Ca{sup 2+} concentration, Mg{sup 2+} concentration, rotation speed, and temperature significantly affect the final required current density of the pulse cathodic protection. The optimum levels of parameters at different frequencies are also presented. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  13. A versatile new method for synthesis and deposition of doped, visible light-activated TiO2 thin films

    DEFF Research Database (Denmark)

    In, Su-il; Kean, A.H.; Orlov, A.

    2009-01-01

    A flexible and widely applicable method allows the deposition of carbon-doped visible light-activated photocatalytic TiO2 thin films on a variety of substrates.......A flexible and widely applicable method allows the deposition of carbon-doped visible light-activated photocatalytic TiO2 thin films on a variety of substrates....

  14. Taguchi Method Applied in Optimization of Shipley SJR 5740 Positive Resist Deposition

    Science.gov (United States)

    Hui, A.; Blosiu, J. O.; Wiberg, D. V.

    1998-01-01

    Taguchi Methods of Robust Design presents a way to optimize output process performance through an organized set of experiments by using orthogonal arrays. Analysis of variance and signal-to-noise ratio is used to evaluate the contribution of each of the process controllable parameters in the realization of the process optimization. In the photoresist deposition process, there are numerous controllable parameters that can affect the surface quality and thickness of the final photoresist layer.

  15. Surface energy evaluation of unhydrogenated DLC thin film deposited by thermionic vacuum arc (TVA) method

    Science.gov (United States)

    Vladoiu, R.; Dinca, V.; Musa, G.

    2009-08-01

    The aim of this paper is concerned with the surface energy evaluation by contact angle measurements of DLC films deposited by thermionic vacuum arc (TVA) on different substrates: glass plate, zinc foil, stainless steel and alumina foil. TVA is an original method based on a combination of the evaporation by electron bombardment and anodic arc. The evaluation of the surface free energy has been carried out by surface energy evaluation system (SEE System). The influence of the experimental conditions is also investigated.

  16. TSC response of irradiated CVD diamond films

    CERN Document Server

    Borchi, E; Bucciolini, M; Guasti, A; Mazzocchi, S; Pirollo, S; Sciortino, S

    1999-01-01

    CVD diamond films have been irradiated with electrons, sup 6 sup 0 Co photons and protons in order to study the dose response to exposure to different particles and energies and to investigate linearity with dose. The Thermally Stimulated Current (TSC) has been studied as a function of the dose delivered to polymethilmetacrilate (PMMA) in the range from 1 to 12 Gy with 20 MeV electrons from a linear accelerator. The TSC spectrum has revealed the presence of two components with peak temperatures of about 470 and 520 K, corresponding to levels lying in the diamond band gap with activation energies of the order of 0.7 - 1 eV. After the subtraction of the exponential background the charge emitted during the heating scan has been evaluated and has been found to depend linearly on the dose. The thermally emitted charge of the CVD diamond films has also been studied using different particles. The samples have been irradiated with the same PMMA dose of about 2 Gy with 6 and 20 MeV electrons from a Linac, sup 6 sup 0 ...

  17. The annual averaged atmospheric dispersion factor and deposition factor according to methods of atmospheric stability classification

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Hae Sun; Jeong, Hyo Joon; Kim, Eun Han; Han, Moon Hee; Hwang, Won Tae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-09-15

    This study analyzes the differences in the annual averaged atmospheric dispersion factor and ground deposition factor produced using two classification methods of atmospheric stability, which are based on a vertical temperature difference and the standard deviation of horizontal wind direction fluctuation. Daedeok and Wolsong nuclear sites were chosen for an assessment, and the meteorological data at 10 m were applied to the evaluation of atmospheric stability. The XOQDOQ software program was used to calculate atmospheric dispersion factors and ground deposition factors. The calculated distances were chosen at 400 m, 800 m, 1,200 m, 1,600 m, 2,400 m, and 3,200 m away from the radioactive material release points. All of the atmospheric dispersion factors generated using the atmospheric stability based on the vertical temperature difference were shown to be higher than those from the standard deviation of horizontal wind direction fluctuation. On the other hand, the ground deposition factors were shown to be same regardless of the classification method, as they were based on the graph obtained from empirical data presented in the Nuclear Regulatory Commission's Regulatory Guide 1.111, which is unrelated to the atmospheric stability for the ground level release. These results are based on the meteorological data collected over the course of one year at the specified sites; however, the classification method of atmospheric stability using the vertical temperature difference is expected to be more conservative.

  18. Design and Development of an Acoustic Levitation System for Use in CVD Growth of Carbon Nanotubes

    Science.gov (United States)

    Qasem, Amal ali

    The most widely used methods for growth of carbon nanotubes (CNTs) arc discharge, laser ablation, and chemical vapor deposition (CVD). Some of these methods have difficulties, such as controlling the quality and straightness of the nanotube in the synthesis of CNTs from substrates. Also, the enhanced plasma chemical vapor deposition method with the catalyst on a substrate produces straighter, larger diameter nanotubes by the tip growth method, but they are short. The difficulty in the floating catalyst method is that the nanotubes stay in the growth furnace for short times limiting growth to about one mm length; this method also leaves many catalyst impurities. One factor that limits CNT growth in these methods is the difficulty of getting enough carbon atoms to the growth catalyst to grow long nanotubes. The motivation of this work is that longer, higher quality nanotubes could be grown by increasing growth time and by increasing carbon atom movement to catalyst. The goal of this project is to use acoustic levitation to assist chemical vapor deposition growth by trapping and vibrating the growing CNTs for better properties. Our levitation system consists of a piezoelectric transducer attached to an aluminum horn and quartz rod extending into the growth furnace. The most important elements of our methods to achieve the acoustic levitation are as follows. 1. Using COMSOL Multi-physic Simulation software to determine the length of quartz rod needed to excite standing waves for levitation in the tube furnace. 2. Determining the resonance frequency of different transducers and horns. 3. Using ultrasound measurement to determine the time of flight, velocity of sound and sound wavelength of different horns. 4. Making Aluminum horns with the appropriate lengths. 5. Using ultrasound measurement to determine the changing of quartz rod velocity of sound and length in the furnace. 6. Mounting the transducer to booster horn and aluminum cylindrical horn above a reflector to

  19. Thermoluminescent properties of CVD diamond: applications to ionising radiation dosimetry; Proprietes thermoluminescentes du diamant CVD: applications a la dosimetrie des rayonnements ionisants

    Energy Technology Data Exchange (ETDEWEB)

    Petitfils, A

    2007-09-15

    Remarkable properties of synthetic diamond (human soft tissue equivalence, chemical stability, non-toxicity) make this material suitable for medical application as thermoluminescent dosimeter (TLD). This work highlights the interest of this material as radiotherapy TLD. In the first stage of this work, we looked after thermoluminescent (TL) and dosimetric properties of polycrystalline diamond made by Chemically Vapor Deposited (CVD) synthesis. Dosimetric characteristics are satisfactory as TLD for medical application. Luminescence thermal quenching on diamond has been investigated. This phenomenon leads to a decrease of dosimetric TL peak sensitivity when the heating rate increases. The second part of this work analyses the use of synthetic diamond as TLD in radiotherapy. Dose profiles, depth dose distributions and the cartography of an electron beam obtained with our samples are in very good agreement with results from an ionisation chamber. It is clearly shown that CVD) diamond is of interest to check beams of treatment accelerators. The use of these samples in a control of treatment with Intensity Modulated Radiation Therapy underlines good response of synthetic diamond in high dose gradient areas. These results indicate that CVD diamond is a promising material for radiotherapy dosimetry. (author)

  20. Method of research and study of uranium deposits; Methode de recherches et d'etude des gites uraniferes

    Energy Technology Data Exchange (ETDEWEB)

    Lenoble, A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1955-07-01

    In a first part, the author gives a fast retrospective of the evaluations of the uranium deposits in the French Union. The author established a method of prospecting and studying, modifiable at all times following the experiences and the results, permitting to make the general inventory of uranium resources on the territory. The method is based on: 1 - the determination of geological guides in order to mark the most promising deposits, 2 - the definition of a methodology adapted to every steps of the research, 3 - the choice of the material adapted for each of the steps. This method, originally established for the prospecting in crystalline massifs, is adaptable to the prospecting of the sedimentary formations. (M.B.) [French] Dans une premiere partie, l'auteur donne une retrospective rapide des estimations des gites uraniferes dans l'Union Francaise. L'auteur a etabli une methode de prospection et d'etude, modifiable a tout instant suivant les experiences et les resultats, permettant de faire l'inventaire general des ressources en uranium du territoire. La methode est base sur: 1 - la determination de guides geologiques afin de reperer les gisements les plus prometteurs, 2 - la definition d'une methodologie adaptee a chaque stade de la recherche, 3 - le choix du materiel adapte pour chacun des stades. Cette methode, a l'origine etablie pour la prospection en massifs cristallins, est adaptable a la prospection des formations sedimentaires. (M.B.)

  1. Iron (III) chloride doping of CVD graphene.

    Science.gov (United States)

    Song, Yi; Fang, Wenjing; Hsu, Allen L; Kong, Jing

    2014-10-03

    Chemical doping has been shown as an effective method of reducing the sheet resistance of graphene. We present the results of our investigations into doping large area chemical vapor deposition graphene using Iron (III) Chloride (FeCl(3)). It is shown that evaporating FeCl(3) can increase the carrier concentration of monolayer graphene to greater than 10(14) cm(-2) and achieve resistances as low as 72 Ω sq(-1). We also evaluate other important properties of the doped graphene such as surface cleanliness, air stability, and solvent stability. Furthermore, we compare FeCl(3) to three other common dopants: Gold (III) Chloride (AuCl(3)), Nitric Acid (HNO(3)), and TFSA ((CF(3)SO(2))(2)NH). We show that compared to these dopants, FeCl(3) can not only achieve better sheet resistance but also has other key advantages including better solvent stability.

  2. A Deposit Contract Method to Deliver Abstinence Reinforcement for Cigarette Smoking

    Science.gov (United States)

    Dallery, Jesse; Meredith, Steven; Glenn, Irene M.

    2008-01-01

    Eight smokers were randomly assigned to a deposit contract ($50.00) or to a no-deposit group. Using a reversal design, participants could recoup their deposit (deposit group) or earn vouchers (no-deposit group) for smoking reductions and abstinence (breath carbon monoxide [CO] less than or equal to 4 parts per million) during treatment phases.…

  3. Copper-vapor-assisted chemical vapor deposition for high-quality and metal-free single-layer graphene on amorphous SiO2 substrate.

    Science.gov (United States)

    Kim, Hyungki; Song, Intek; Park, Chibeom; Son, Minhyeok; Hong, Misun; Kim, Youngwook; Kim, Jun Sung; Shin, Hyun-Joon; Baik, Jaeyoon; Choi, Hee Cheul

    2013-08-27

    We report that high-quality single-layer graphene (SLG) has been successfully synthesized directly on various dielectric substrates including amorphous SiO2/Si by a Cu-vapor-assisted chemical vapor deposition (CVD) process. The Cu vapors produced by the sublimation of Cu foil that is suspended above target substrates without physical contact catalyze the pyrolysis of methane gas and assist nucleation of graphene on the substrates. Raman spectra and mapping images reveal that the graphene formed on a SiO2/Si substrate is almost defect-free and homogeneous single layer. The overall quality of graphene grown by Cu-vapor-assisted CVD is comparable to that of the graphene grown by regular metal-catalyzed CVD on a Cu foil. While Cu vapor induces the nucleation and growth of SLG on an amorphous substrate, the resulting SLG is confirmed to be Cu-free by synchrotron X-ray photoelectron spectroscopy. The SLG grown by Cu-vapor-assisted CVD is fabricated into field effect transistor devices without transfer steps that are generally required when SLG is grown by regular CVD process on metal catalyst substrates. This method has overcome two important hurdles previously present when the catalyst-free CVD process is used for the growth of SLG on fused quartz and hexagonal boron nitride substrates, that is, high degree of structural defects and limited size of resulting graphene, respectively.

  4. Low Temperature Pulsed Plasma Deposition. Part 3. A Method of Deposition of Aluminum and Tin at Room Temperature

    Science.gov (United States)

    1989-05-23

    aluminium oxide . 5 Similarly, the films of tin produced from continuous flows of TNT, argon, and hydrogen were brown, soft, and had no metallic lustre...deposition such that all the carbon in the film had reacted with moisture in the air to form aluminium oxide . The apparent silicon content is due to the

  5. Low-temperature SiON films deposited by plasma-enhanced atomic layer deposition method using activated silicon precursor

    Energy Technology Data Exchange (ETDEWEB)

    Suh, Sungin; Kim, Jun-Rae; Kim, Seongkyung; Hwang, Cheol Seong; Kim, Hyeong Joon, E-mail: thinfilm@snu.ac.kr [Department of Materials Science and Engineering with Inter-University Semiconductor Research Center (ISRC), Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 08826 (Korea, Republic of); Ryu, Seung Wook, E-mail: tazryu78@gmail.com [Department of Electrical Engineering, Stanford University, Stanford, California 94305-2311 (United States); Cho, Seongjae [Department of Electronic Engineering and New Technology Component & Material Research Center (NCMRC), Gachon University, Seongnam-si, Gyeonggi-do 13120 (Korea, Republic of)

    2016-01-15

    It has not been an easy task to deposit SiN at low temperature by conventional plasma-enhanced atomic layer deposition (PE-ALD) since Si organic precursors generally have high activation energy for adsorption of the Si atoms on the Si-N networks. In this work, in order to achieve successful deposition of SiN film at low temperature, the plasma processing steps in the PE-ALD have been modified for easier activation of Si precursors. In this modification, the efficiency of chemisorption of Si precursor has been improved by additional plasma steps after purging of the Si precursor. As the result, the SiN films prepared by the modified PE-ALD processes demonstrated higher purity of Si and N atoms with unwanted impurities such as C and O having below 10 at. % and Si-rich films could be formed consequently. Also, a very high step coverage ratio of 97% was obtained. Furthermore, the process-optimized SiN film showed a permissible charge-trapping capability with a wide memory window of 3.1 V when a capacitor structure was fabricated and measured with an insertion of the SiN film as the charge-trap layer. The modified PE-ALD process using the activated Si precursor would be one of the most practical and promising solutions for SiN deposition with lower thermal budget and higher cost-effectiveness.

  6. Parametric optimization during machining of AISI 304 Austenitic Stainless Steel using CVD coated DURATOMIC cutting insert

    Directory of Open Access Journals (Sweden)

    M. Kaladhar

    2012-08-01

    Full Text Available In this work, Taguchi method is applied to determine the optimum process parameters for turning of AISI 304 austenitic stainless steel on CNC lathe. A Chemical vapour deposition (CVD coated cemented carbide cutting insert is used which is produced by DuratomicTM technology of 0.4 and 0.8 mm nose radii. The tests are conducted at four levels of Cutting speed, feed and depth of cut. The influence of these parameters are investigated on the surface roughness and material removal rate (MRR. The Analysis Of Variance (ANOVA is also used to analyze the influence of cutting parameters during machining. The results revealed that cutting speed significantly (46.05% affected the machined surface roughness values followed by nose radius (23.7%. The influence of the depth of cut (61.31% in affecting material removal rate (MRR is significantly large. The cutting speed (20.40% is the next significant factor. Optimal range and optimal level of parameters are also predicted for responses.

  7. High Current-Induced Electron Redistribution in a CVD-Grown Graphene Wide Constriction

    Directory of Open Access Journals (Sweden)

    Chiashain Chuang

    2016-01-01

    Full Text Available Investigating the charge transport behavior in one-dimensional quantum confined system such as the localized states and interference effects due to the nanoscale grain boundaries and merged domains in wide chemical vapor deposition graphene constriction is highly desirable since it would help to realize industrial graphene-based electronic device applications. Our data suggests a crossover from interference coherent transport to carriers flushing into grain boundaries and merged domains when increasing the current. Moreover, many-body fermionic carriers with disordered system in our case can be statistically described by mean-field Gross-Pitaevskii equation via a single wave function by means of the quantum hydrodynamic approximation. The novel numerical simulation method supports the experimental results and suggests that the extreme high barrier potential regions on graphene from the grain boundaries and merged domains can be strongly affected by additional hot charges. Such interesting results could pave the way for quantum transport device by supplying additional hot current to flood into the grain boundaries and merged domains in one-dimensional quantum confined CVD graphene, a great advantage for developing graphene-based coherent electronic devices.

  8. The High performance of nanocrystalline CVD diamond coated hip joints in wear simulator test.

    Science.gov (United States)

    Maru, M M; Amaral, M; Rodrigues, S P; Santos, R; Gouvea, C P; Archanjo, B S; Trommer, R M; Oliveira, F J; Silva, R F; Achete, C A

    2015-09-01

    The superior biotribological performance of nanocrystalline diamond (NCD) coatings grown by a chemical vapor deposition (CVD) method was already shown to demonstrate high wear resistance in ball on plate experiments under physiological liquid lubrication. However, tests with a close-to-real approach were missing and this constitutes the aim of the present work. Hip joint wear simulator tests were performed with cups and heads made of silicon nitride coated with NCD of ~10 μm in thickness. Five million testing cycles (Mc) were run, which represent nearly five years of hip joint implant activity in a patient. For the wear analysis, gravimetry, profilometry, scanning electron microscopy and Raman spectroscopy techniques were used. After 0.5 Mc of wear test, truncation of the protruded regions of the NCD film happened as a result of a fine-scale abrasive wear mechanism, evolving to extensive plateau regions and highly polished surface condition (Ra<10nm). Such surface modification took place without any catastrophic features as cracking, grain pullouts or delamination of the coatings. A steady state volumetric wear rate of 0.02 mm(3)/Mc, equivalent to a linear wear of 0.27 μm/Mc favorably compares with the best performance reported in the literature for the fourth generation alumina ceramic (0.05 mm(3)/Mc). Also, squeaking, quite common phenomenon in hard-on-hard systems, was absent in the present all-NCD system.

  9. The Effects of Exercise Therapy on CVD Risk Factors in Women

    OpenAIRE

    Hur, Sun; Kim, Seon-Rye

    2014-01-01

    [Purpose] The purpose of this study was to search for the association of Type D personality and CVD risk factors through comparison of the association of exercise participation with CVD risk factors in women. [Subjects] The research subjects were randomly assigned to four groups: Type D+Exercise (n=12), Type D+non-exercise (n=12), non-Type D+Exercise (n=12), and non-Type D+non-exercise (n=10). The study consisted of 46 participants. [Methods] An aerobic exercise program and meditation were co...

  10. Zirconia coatings deposited by novel plasma-enhanced aerosol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Miszczak, Sebastian; Pietrzyk, Bozena; Kucharski, Daniel [Institute of Materials Science and Engineering, Lodz University of Technology (Poland)

    2016-05-15

    The sol-gel technique is well known and widely used for manufacturing coatings. An aerosol-gel method is a modification of the classic sol-gel process. Preparation of coatings by this technique involves the formation of an aerosol and its deposition on the coated surfaces, where the aerosol droplets merge into a continuous layer. In this work, an aerosol-gel routine, enhanced with a low-temperature plasma discharge, was used to produce zirconia coatings on different substrates. Low-temperature plasma was used for preactivation of substrate surfaces prior to the sol deposition, and for treatment of deposited layers. The obtained coatings were characterized using optical, electron (SEM), and atomic force (AFM) microscopes, a contact-angle device, a scratch tester, a grazing-incidence X-ray diffractometer (GIXRD), and an infrared spectrometer (FTIR). The results showed a significant influence of substrate plasma pretreatment on the formation and morphology of zirconia thin films. A noticeable effect of low-temperature plasma treatment on the structure and properties of the obtained coatings was also presented. These results allow possible applications of this method for the preparation of zirconia coatings on temperature-sensitive substrates to be predicted. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Method to grow pure nanocrystalline diamond films at low temperatures and high deposition rates

    Science.gov (United States)

    Carlisle, John A.; Gruen, Dieter M.; Auciello, Orlando; Xiao, Xingcheng

    2009-07-07

    A method of depositing nanocrystalline diamond film on a substrate at a rate of not less than about 0.2 microns/hour at a substrate temperature less than about 500.degree. C. The method includes seeding the substrate surface with nanocrystalline diamond powder to an areal density of not less than about 10.sup.10sites/cm.sup.2, and contacting the seeded substrate surface with a gas of about 99% by volume of an inert gas other than helium and about 1% by volume of methane or hydrogen and one or more of acetylene, fullerene and anthracene in the presence of a microwave induced plasma while maintaining the substrate temperature less than about 500.degree. C. to deposit nanocrystalline diamond on the seeded substrate surface at a rate not less than about 0.2 microns/hour. Coatings of nanocrystalline diamond with average particle diameters of less than about 20 nanometers can be deposited with thermal budgets of 500.degree. C.-4 hours or less onto a variety of substrates such as MEMS devices.

  12. Physical and electrochemical study of platinum thin films deposited by sputtering and electrochemical methods

    Energy Technology Data Exchange (ETDEWEB)

    Quinones, C. [Universidad de Cartagena, Cartagena de Indias (Colombia); Departamento de Quimica, Universidad Nacional de Colombia, Cra. 30 No 45-03, Bogota (Colombia); Vallejo, W., E-mail: wavallejol@unal.edu.co [Departamento de Quimica, Universidad Nacional de Colombia, Cra. 30 No 45-03, Bogota (Colombia); Mesa, F. [Departamento de Ciencias Basicas, Universidad Libre, Carrera 70 No 53-40, Bogota (Colombia)

    2011-06-15

    In this work platinum thin films deposited by sputtering and electrochemical methods were characterized through physical and electrochemical analysis. The as-grown platinum thin films were characterized through X-ray diffraction (XRD), atomic force microscopy (AFM); scanning electronic microscopy (SEM) and through electrochemical impedance spectroscopy (EIS) measurements. Structural studies indicated that platinum thin films were polycrystalline. Morphological characteristics were significantly affected by the substrate type and synthesis method. Finally the EIS analysis indicated that platinum films were electrochemically stable and present both low resistance of charge transfer and low series resistance; the equivalent circuit of platinum interface has been proposed.

  13. Methods of depositing an alpha-silicon-carbide-containing film at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Habermehl, Scott D.

    2017-01-17

    Described methods are useful for depositing a silicon carbide film including Alpha-SiC at low temperatures (e.g., below about 1400.degree. C.), and resulting multi-layer structures and devices. A method includes introducing a chlorinated hydrocarbon gas and a chlorosilicon gas into a reaction chamber, and reacting the chlorinated hydrocarbon gas with the chlorosilicon gas at a temperature of less than about 1400.degree. C. to grow the silicon carbide film. The silicon carbide film so-formed includes Alpha-SiC.

  14. Preparation of yttria-stabilized zirconia films for solid oxide fuel cells by electrophoretic deposition method

    Energy Technology Data Exchange (ETDEWEB)

    Ishihara, Tatsumi; Sato, Keiji; Mizuhara, Yukako; Takita, Yusaku (Oita Univ. (Japan). Faculty of Engineering)

    1992-06-01

    The electrophoretic deposition (EPD) method was applied for the preparation of yttria-stabilized zirconia (YSZ) films for a solid oxide fuel cell (SOFC). Dense YSZ films with uniform thickness can be readily prepared by EPD method. When the planar SOFC was fabricated by using La[sub 0.6]Sr[sub 0.4]MnO[sub 3] as a cathode and electroless plating Pt as an anode, the open circuit voltage and the maximum power density attained were 1.03 V and 1.87 W cm[sup -2], respectively. (author).

  15. Synthesis and Characterization of Molybdenum Doped ZnO Thin Films by SILAR Deposition Method

    Science.gov (United States)

    Radha, R.; Sakthivelu, A.; Pradhabhan, D.

    2016-08-01

    Molybdenum (Mo) doped zinc oxide (ZnO) thin films were deposited on the glass substrate by Successive Ionic Layer Adsorption and Reaction (SILAR) deposition method. The effect of Mo dopant concentration of 5, 6.6 and 10 mol% on the structural, morphological, optical and electrical properties of n-type Mo doped ZnO films was studied. The X-ray diffraction (XRD) results confirmed that the Mo doped ZnO thin films were polycrystalline with wurtzite structure. The field emission scanning electron microscopy (FESEM) studies shows that the surface morphology of the films changes with Mo doping. A blue shift of the optical band gap was observed in the optical studies. Effect of Mo dopant concentration on electrical conductivity was studied and it shows comparatively high electrical conductivity at 10 mol% of Mo doping concentration.

  16. Apparatus and method for pulsed laser deposition of materials on wires and pipes

    Science.gov (United States)

    Fernandez, Felix E. (Inventor)

    2003-01-01

    Methods and apparatuses are disclosed which allow uniform coatings to be applied by pulsed laser deposition (PLD) on inner and outer surfaces of cylindrical objects, such as rods, pipes, tubes, and wires. The use of PLD makes this technique particularly suitable for complex multicomponent materials, such as superconducting ceramics. Rigid objects of any length, i.e., pipes up to a few meters, and with diameters from less than 1 centimeter to over 10 centimeters can be coated using this technique. Further, deposition is effected simultaneously onto an annular region of the pipe wall. This particular arrangement simplifies the apparatus, reduces film uniformity control difficulties, and can result in faster operation cycles. In addition, flexible wires of any length can be continuously coated using the disclosed invention.

  17. Dopamine/TiO{sub 2} hybrid thin films prepared by the liquid phase deposition method

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez-Tauste, David [Departament de Quimica, Universitat Autonoma de Barcelona, Campus UAB, Edifici Cn, 08290 Cerdanyola del Valles, Barcelona (Spain)], E-mail: davidg@qf.uab.es; Domenech, Xavier [Departament de Quimica, Universitat Autonoma de Barcelona, Campus UAB, Edifici Cn, 08290 Cerdanyola del Valles, Barcelona (Spain); Domingo, Concepcion [Instituto de Ciencia de Materiales (CSIC), Campus UAB, 08290 Cerdanyola del Valles, Barcelona (Spain); Ayllon, Jose A. [Departament de Quimica, Universitat Autonoma de Barcelona, Campus UAB, Edifici Cn, 08290 Cerdanyola del Valles, Barcelona (Spain)

    2008-04-30

    Liquid phase deposition method is applied to one-step production of a hybrid material composed by dopamine(DA) and TiO{sub 2} anatase. An optimized amount of the enediol derivative is added to a fluoride titania precursor aqueous solution in order to entrap this modifier within the growing TiO{sub 2}, yielding a DA/TiO{sub 2} nanocomposite material. Uniform, well-adhered and brown-colored thin films are deposited on indium tin oxide covered glass substrate. The DA/TiO{sub 2} hybrid material has been characterized by infrared spectroscopy, electronic microscopy, X-ray diffraction and UV-vis spectroscopy. The formation of the hybrid material seems to be reasonably explained by linkage of different TiO{sub 2} nanocrystallites taking advantage of both enediol and amine groups of DA.

  18. Low Temperature Growth of Vertically Aligned Carbon Nanotubes via Floating Catalyst Chemical Vapor Deposition Method

    Institute of Scientific and Technical Information of China (English)

    M.R. Atiyan; D.R. Awang Biak; F. Ahmadun; I.S. Ahamad; F. Mohd Yasin; H. Mohamed Yusoff

    2011-01-01

    Synthesis of carbon nanotubes (CNTs) below 600℃ using supporting catalyst chemical vapor deposition method was reported by many research groups. However, the floating catalyst chemical vapor deposition received less attention due to imperfect nanotubes produced. In this work, the effects of varying the preheating temperature on the synthesis of CNT were investigated. The reaction temperature was set at 570℃. The preheating set temperature was varied from 150 to 400℃ at 50℃ interval. Three O-ring shape heating mantels were used as heating source for the preheater. In situ monitoring device was used to observe the temperature profile in the reactor. Benzene and ferrocene were used as the carbon source and catalyst precursor, respectively. Vertically aligned CNTs were synthesized when the preheating temperature was set at 400℃. When the preheating temperature was increased up to 400℃, both the length and the alignment of CNTs produced were improved.

  19. Application of Taguchi Method to the Optimization of a-C:H Coatings Deposited Using Ion Beam Assisted Physical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    W. H. Kao

    2015-02-01

    Full Text Available The Taguchi design method is used to optimize the adhesion, hardness, and wear resistance properties of a-C:H coatings deposited on AISI M2 steel substrates using the ion beam assisted physical vapor deposition method. The adhesion strength of the coatings is evaluated by means of scratch tests, while the hardness is measured using a nanoindentation tester. Finally, the wear resistance is evaluated by performing cyclic ball-on-disc wear tests. The Taguchi experimental results show that the optimal deposition parameters are as follows: a substrate bias voltage of 90 V, an ion beam voltage of 1 kV, an acetylene flow rate of 21 sccm, and a working distance of 7 cm. Given these optimal processing conditions, the a-C:H coating has a critical load of 99.8 N, a hardness of 25.5 GPa, and a wear rate of 0.4 × 10−6 mm3/Nm.

  20. Method for producing microstructured templates and their use in providing pinning enhancements in superconducting films deposited thereon

    Science.gov (United States)

    Aytug, Tolga; Paranthaman, Mariappan Parans; Polat, Ozgur

    2013-07-16

    The present invention relates to a method for producing a phase-separated layer useful as a flux pinning substrate for a superconducting film, wherein the method includes subjecting at least a first and a second target material to a sputtering deposition technique in order that a phase-separated layer is deposited epitaxially on a primary substrate containing an ordered surface layer. The invention is also directed to a method for producing a superconducting tape containing pinning defects therein by depositing a superconducting film on a phase-separated layer produced by the method described above.

  1. Chemical Properties of Carbon Nanotubes Prepared Using Camphoric Carbon by Thermal-CVD

    Science.gov (United States)

    Azira, A. A.; Rusop, M.

    2010-03-01

    Chemical properties and surface study on the influence of starting carbon materials by using thermal chemical vapor deposition (Thermal-CVD) to produced carbon nanotubes (CNTs) is investigated. The CNTs derived from camphor were synthesized as the precursor material due to low sublimation temperature. The major parameters are also evaluated in order to obtain high-yield and high-quality CNTs. The prepared CNTs are examined using field emission scanning electron microscopy (FESEM) to determine the microstructure of nanocarbons. The FESEM investigation of the CNTs formed on the support catalysts provides evidence that camphor is suitable as a precursor material for nanotubes formation. The chemical properties of the CNTs were conducted using FTIR spectroscopy and PXRD analysis. The high-temperature graphitization process induced by the Thermal-CVD enables the hydrocarbons to act as carbon sources and changes the aromatic species into the layered graphite structure of CNTs.

  2. Electronic properties and strain sensitivity of CVD-grown graphene with acetylene

    Science.gov (United States)

    Yang, Meng; Sasaki, Shinichirou; Ohnishi, Masato; Suzuki, Ken; Miura, Hideo

    2016-04-01

    Although many studies have shown that large-area monolayer graphene can be formed by chemical vapor deposition (CVD) using methane gas, the growth of monolayer graphene using highly reactive acetylene gas remains a big challenge. In this study, we synthesized a uniform monolayer graphene film by low-pressure CVD (LPCVD) with acetylene gas. On the base of Raman spectroscopy measurements, it was found that up to 95% of the as-grown graphene is monolayer. The electronic properties and strain sensitivity of the LPCVD-grown graphene with acetylene were also evaluated by testing the fabricated field-effect transistors (FETs) and strain sensors. The derived carrier mobility and gauge factor are 862-1150 cm2/(V·s) and 3.4, respectively, revealing the potential for high-speed FETs and strain sensor applications. We also investigated the relationship between the electronic properties and the graphene domain size.

  3. Aligned carbon nanotubes catalytically grown on iron-based nanoparticles obtained by laser-induced CVD

    Energy Technology Data Exchange (ETDEWEB)

    Le Normand, F. [Groupe Surfaces and Interfaces, IPCMS, UMR 7504 CNRS, Bat 70, 23 rue du Loess, 67034 Strasbourg Cedex (France)], E-mail: Francois.Le-Normand@ipcms.u-strasbg.fr; Cojocaru, C.S.; Ersen, O. [Groupe Surfaces and Interfaces, IPCMS, UMR 7504 CNRS, Bat 70, 23 rue du Loess, 67034 Strasbourg Cedex (France); Legagneux, P.; Gangloff, L. [THALES R and T, Departementale 128, 91747 Palaiseau Cedex (France); Fleaca, C. [Groupe Surfaces and Interfaces, IPCMS, UMR 7504 CNRS, Bat 70, 23 rue du Loess, 67034 Strasbourg Cedex (France); National Institute for Lasers, Plasma and Radiation Physics, Laser Department, P.O. Box MG-36, R-76900 Bucharest (Romania); Alexandrescu, R.; Dumitrache, F.; Morjan, I. [National Institute for Lasers, Plasma and Radiation Physics, Laser Department, P.O. Box MG-36, R-76900 Bucharest (Romania)

    2007-12-15

    Iron-based nanoparticles are prepared by a laser-induced chemical vapor deposition (CVD) process. They are characterized as body-centered Fe and Fe{sub 2}O{sub 3} (maghemite/magnetite) particles with sizes {<=}5 and 10 nm, respectively. The Fe particles are embedded in a protective carbon matrix. Both kind of particles are dispersed by spin-coating on SiO{sub 2}/Si(1 0 0) flat substrates. They are used as catalyst to grow carbon nanotubes by a plasma- and filaments-assisted catalytic CVD process (PE-HF-CCVD). Vertically oriented and thin carbon nanotubes (CNTs) were grown with few differences between the two samples, except the diameter in relation to the initial size of the iron particles, and the density. The electron field emission of these samples exhibit quite interesting behavior with a low turn-on voltage at around 1 V/{mu}m.

  4. Aligned carbon nanotubes catalytically grown on iron-based nanoparticles obtained by laser-induced CVD

    Science.gov (United States)

    Le Normand, F.; Cojocaru, C. S.; Ersen, O.; Legagneux, P.; Gangloff, L.; Fleaca, C.; Alexandrescu, R.; Dumitrache, F.; Morjan, I.

    2007-12-01

    Iron-based nanoparticles are prepared by a laser-induced chemical vapor deposition (CVD) process. They are characterized as body-centered Fe and Fe 2O 3 (maghemite/magnetite) particles with sizes ≤5 and 10 nm, respectively. The Fe particles are embedded in a protective carbon matrix. Both kind of particles are dispersed by spin-coating on SiO 2/Si(1 0 0) flat substrates. They are used as catalyst to grow carbon nanotubes by a plasma- and filaments-assisted catalytic CVD process (PE-HF-CCVD). Vertically oriented and thin carbon nanotubes (CNTs) were grown with few differences between the two samples, except the diameter in relation to the initial size of the iron particles, and the density. The electron field emission of these samples exhibit quite interesting behavior with a low turn-on voltage at around 1 V/μm.

  5. Cold Vacuum Drying (CVD) Set Point Determination

    Energy Technology Data Exchange (ETDEWEB)

    PHILIPP, B.L.

    2000-01-12

    This document provides the calculations used to determine the error of safety class signals used for the CVD process These errors are used with the Parameter limits to arrive at the initial set point. The Safety Class Instrumentation and Control (SCIC) system provides active detection and response to process anomalies that, if unmitigated would result in a safety event. Specifically actuation of the SCIC system includes two portions. The portion which isolates the MCO and initiates the safety-class helium (SCHe) purge, and the portion which detects and stops excessive heat input to the MCO on high tempered water MCO inlet temperature. For the MCO isolation and purge the SCIC receives signals from MCO pressure (both positive pressure and vacuum) helium flow rate, bay high temperature switches, seismic trips and time under vacuum trips.

  6. CVD diamond sensors for charged particle detection

    CERN Document Server

    Krammer, Manfred; Berdermann, E; Bergonzo, P; Bertuccio, G; Bogani, F; Borchi, E; Brambilla, A; Bruzzi, Mara; Colledani, C; Conway, J; D'Angelo, P; Dabrowski, W; Delpierre, P A; Dencuville, A; Dulinski, W; van Eijk, B; Fallou, A; Fizzotti, F; Foulon, F; Friedl, M; Gan, K K; Gheeraert, E; Hallewell, G D; Han, S; Hartjes, F G; Hrubec, Josef; Husson, D; Kagan, H; Kania, D R; Kaplon, J; Kass, R; Koeth, T W; Lo Giudice, A; Lü, R; MacLynne, L; Manfredotti, C; Meier, D; Mishina, M; Moroni, L; Oh, A; Pan, L S; Pernicka, Manfred; Peitz, A; Perera, L P; Pirollo, S; Procario, M; Riester, J L; Roe, S; Rousseau, L; Rudge, A; Russ, J; Sala, S; Sampietro, M; Schnetzer, S; Sciortino, S; Stelzer, H; Stone, R; Suter, B; Tapper, R J; Tesarek, R; Trischuk, W; Tromson, D; Vittone, E; Walsh, A M; Wedenig, R; Weilhammer, Peter; Wetstein, M; White, C; Zeuner, W; Zöller, M

    2001-01-01

    CVD diamond material was used to build position-sensitive detectors for single-charged particles to be employed in high-intensity physics experiments. To obtain position information, metal contacts shaped as strips or pixels are applied to the detector surface for one- or two- dimensional coordinate measurement. Strip detectors 2*4 cm/sup 2/ in size with a strip distance of 50 mu m were tested. Pixel detectors of various pixel sizes were bump bonded to electronics chips and investigated. A key issue for the use of these sensors in high intensity experiments is the radiation hardness. Several irradiation experiments were carried out with pions, protons and neutrons exceeding a fluence of 10/sup 15/ particles/cm/sup 2/. The paper presents an overview of the results obtained with strip and pixel detectors in high-energy test beams and summarises the irradiation studies. (8 refs).

  7. Methods of trend analysis for atmospheric deposition into the sea; Trendabschaetzung atmosphaerischer Stoffeintraege in die Meere

    Energy Technology Data Exchange (ETDEWEB)

    Kuhbier, P.; Uhlig, S.; Fraenzel, A.; Schick, N.

    2001-02-01

    In order to prevent a considerable deterioration in the detectability of time trends in depositions as a result of fluctuations in the climatic conditions, an adjustment whereby the entry data are recomputed into an 'average' weather conditions appears inevitable. Accordingly, the aim of the project was the development of a concept for the adjustment and trend analysis of depositions including the examination of a number of statistical methods, with the form of the adjustment being the focus of the work. As per this concept, adjustment takes place on the basis of monthly data. The adjusted depositions are then summarized before trend analysis follows on the basis of these adjusted annual depositions. Finally the trend sensitivity of the method is examined as part of a power analysis. A data bank-based software was developed as part of the project in order to carry out the extensive calculations. With this software, the most diverse trend analysis and adjustment methods were realised and tested. It may first of all be noted that the evaluations conducted confirm the practicality of the adjustment concept developed, with various methods being deployable for fixing the adjustment parameter according to the measurement site and parameter concerned. The average reduction in the scatter of the annual depositions vis-'a-vis the non-adjusted depositions is over 40%. This amounts to a substantial improvement in trend sensitivity and makes for a clear reduction in the length of the requisite time series. However, there is no method among the adjustment methods investigated which, considering all the prerequisites, may be regarded as being superior to the other methods. The question as to which form of adjustment yields the most favourable results depends on the pollutants and the site-related conditions in each case. (orig.) [German] Um zu verhindern, dass durch klimatische Schwankungen die Nachweisbarkeit zeitlicher Trends in Depositionen wesentlich

  8. Ultrafast deposition of silicon nitride and semiconductor silicon thin films by Hot Wire Chemical Vapor Deposition

    NARCIS (Netherlands)

    Schropp, R.E.I.; van der Werf, C.H.M.; Verlaan, V.; Rath, J.K.; Li, H. B. T.

    2009-01-01

    The technology of Hot Wire Chemical Vapor Deposition (HWCVD) or Catalytic Chemical Vapor Deposition (Cat-CVD) has made great progress during the last couple of years. This review discusses examples of significant progress. Specifically, silicon nitride deposition by HWCVD (HW-SiNx) is highlighted, a

  9. A novel method for assessing respiratory deposition of welding fume nanoparticles.

    Science.gov (United States)

    Cena, L G; Keane, M J; Chisholm, W P; Stone, S; Harper, M; Chen, B T

    2014-01-01

    Welders are exposed to high concentrations of nanoparticles. Compared to larger particles, nanoparticles have been associated with more toxic effects at the cellular level, including the generation of more reactive oxygen species activity. Current methods for welding-fume aerosol exposures do not differentiate between the nano-fraction and the larger particles. The objectives of this work are to establish a method to estimate the respiratory deposition of the nano-fraction of selected metals in welding fumes and test this method in a laboratory setting. Manganese (Mn), Nickel (Ni), Chromium (Cr), and hexavalent chromium (Cr(VI)) are commonly found in welding fume aerosols and have been linked with severe adverse health outcomes. Inductively coupled plasma mass spectrometry (ICP-MS) and ion chromatography (IC) were evaluated as methods for analyzing the content of Mn, Ni, Cr, and Cr(VI) nanoparticles in welding fumes collected with nanoparticle respiratory deposition (NRD) samplers. NRD samplers collect nanoparticles at deposition efficiencies that closely resemble physiological deposition in the respiratory tract. The limits of detection (LODs) and quantitation (LOQs) for ICP-MS and IC were determined analytically. Mild and stainless steel welding fumes generated with a robotic welder were collected with NRD samplers inside a chamber. LODs (LOQs) for Mn, Ni, Cr, and Cr(VI) were 1.3 μg (4.43 μg), 0.4 μg (1.14 μg), 1.1 μg (3.33 μg), and 0.4 μg (1.42 μg), respectively. Recovery of spiked samples and certified welding fume reference material was greater than 95%. When testing the method, the average percentage of total mass concentrations collected by the NRD samplers was ~30% for Mn, ~50% for Cr, and ~60% for Ni, indicating that a large fraction of the metals may lie in the nanoparticle fraction. This knowledge is critical to the development of toxicological studies aimed at finding links between exposure to welding fume nanoparticles and adverse health

  10. National implementation of the UNECE convention on long-range transboundary air pollution (effects). Pt. 1. Deposition loads: methods, modelling and mapping results, trends

    Energy Technology Data Exchange (ETDEWEB)

    Gauger, Thomas [Federal Agricultural Research Centre, Braunschweig (DE). Inst. of Agroecology (FAL-AOE); Stuttgart Univ. (Germany). Inst. of Navigation; Haenel, Hans-Dieter; Roesemann, Claus [Federal Agricultural Research Centre, Braunschweig (DE). Inst. of Agroecology (FAL-AOE)] (and others)

    2008-09-15

    The report on the implementation of the UNECE convention on long-range transboundary air pollution Pt.1, deposition loads (methods, modeling and mapping results, trends) includes the following chapters: Introduction, deposition on air pollutants used for the input for critical loads in exceeding calculations, methods applied for mapping total deposition loads, mapping wet deposition, wet deposition mapping results, mapping dry deposition, dry deposition mapping results, cloud and fog mapping results, total deposition mapping results, modeling the air concentration of acidifying components and heavy metals, agricultural emissions of acidifying and eutrophying species.

  11. Nitrogen doping of CVD multiwalled carbon nanotubes: Observation of a large g-factor shift

    Energy Technology Data Exchange (ETDEWEB)

    Mhlanga, Sabelo D., E-mail: Sabelo.Mhlanga@wits.ac.za [Molecular Sciences Institute, School of Chemistry and the DST/NRF Centre of Excellence in Strong Materials, University of the Witwatersrand, Private Bag 3, Wits, 2050 Johannesburg (South Africa); Nxumalo, Edward N.; Coville, Neil J. [Molecular Sciences Institute, School of Chemistry and the DST/NRF Centre of Excellence in Strong Materials, University of the Witwatersrand, Private Bag 3, Wits, 2050 Johannesburg (South Africa); Srinivasu, Vallabhapurapu V., E-mail: vallavs@unisa.ac.za [Department of Physics, University of South Africa, P.O. Box 392, Pretoria 0003 (South Africa)

    2011-11-01

    Highlights: {yields} High quality nitrogen doped multiwalled carbon nanotubes were synthesized using the floating catalyst CVD method. {yields} Systematic ESR measurements of the carbon products produced, in the temperature range of 293-400 K showed line widths that were in general very large {approx} kOe. {yields} A large g-factor shift in samples of N-CNTs from that of the free electron g-factor was observed. Further, the shift increased with increasing temperature. The large g shift has been analysed in terms of Elliott-Wagoner and Bottleneck models. {yields} The temperature dependence of the g shift in the N-CNT samples rules out the Elliott-Wagoner type spin-orbit coupling scenario. {yields} The large g shift and temperature dependence can be qualitatively explained in terms of Bottleneck model. - Abstract: Nitrogen doped multi-walled carbon nanotubes (N-CNTs) and undoped multi-walled carbon nanotubes (MWCNTs) were synthesized by a chemical vapour deposition (CVD) floating catalyst method. The N-CNTs were synthesized by the decomposition of a ferrocene/N-source/toluene (N-source = triethylamine, dimethylamine, acetonitrile) mixture at 900 deg. C. The undoped MWCNTs were synthesized using a ferrocene-toluene mixture without a nitrogen source under similar reaction conditions. The structure of the N-CNTs and MWCNTs was ascertained using HRTEM, SEM and Raman spectroscopy. Systematic ESR measurements of the carbon products produced, in the temperature range of 293-400 K showed line widths that were in general very large {approx} kOe. Most importantly, a large g-factor shift in samples of N-CNTs from that of the free electron g-factor was observed. Further, the shift increased with increasing temperature. The large g shift has been analysed in terms of Elliott-Wagoner and Bottleneck models. The temperature dependence of the g shift in the N-CNT samples rules out the Elliott-Wagoner type spin-orbit coupling scenario. The large g shift and temperature dependence can

  12. Premature menopause linked to CVD and osteoporosis.

    Science.gov (United States)

    Park, Claire; Overton, Caroline

    2010-03-01

    Premature menopause affects 1% of women under the age of 40, the usual age of the menopause is 51. Most women will present with irregular periods or no periods at all with or without climacteric symptoms. Around 10% of women present with primary amenorrhoea. A careful history and examination are required. It is important to ask specifically about previous chemotherapy or radiotherapy and to look for signs of androgen excess e.g. polycystic ovarian syndrome, adrenal problems e.g. galactorrhoea and thyroid goitres. Once pregnancy has been excluded, a progestagen challenge test can be performed in primary care. Norethisterone 5 mg tds po for ten days or alternatively medroxyprogesterone acetate 10 mg daily for ten days is prescribed. A withdrawal bleed within a few days of stopping the norethisterone indicates the presence of oestrogen and bleeding more than a few drops is considered a positive withdrawal bleed. The absence of a bleed indicates low levels of oestrogen, putting the woman at risk of CVD and osteoporosis. FSH levels above 30 IU/l are an indicator that the ovaries are failing and the menopause is approaching or has occurred. It should be remembered that FSH levels fluctuate during the month and from one month to the next, so a minimum of two measurements should be made at least four to six weeks apart. The presence of a bleed should not exclude premature menopause as part of the differential diagnosis as there can be varying and unpredictable ovarian function remaining. The progestagen challenge test should not be used alone, but in conjunction with FSH, LH and oestradiol. There is no treatment for premature menopause. Women desiring pregnancy should be referred to a fertility clinic and discussion of egg donation. Women not wishing to become pregnant should be prescribed HRT until the age of 50 to control symptoms of oestrogen deficiency and reduce the risks of osteoporosis and CVD.

  13. Electrochemical Deposition of Si-Ca/P on Nanotube Formed Beta Ti Alloy by Cyclic Voltammetry Method.

    Science.gov (United States)

    Jeong, Yong-Hoon; Choe, Han-Cheol

    2015-08-01

    The purpose of this study was to investigate electrochemical deposition of Si-Ca/P on nanotube formed Ti-35Nb-10Zr alloy by cyclic voltammetry method. Electrochemical deposition of Si substituted Ca/P was performed by pulsing the applied potential on nanotube formed surface. The surface characteristics were observed by field-emission scanning electron microscopy, X-ray diffractometer, and potentiodynamic polarization test. The phase structure and surface morphologies of Si-Ca/P deposition were affected by deposition cycles. From the anodic polarization test, nanotube formed surface at 20 V showed the high corrosion resistance with lower value of Icorr, I300, and Ipass.

  14. Influence of deposition rate on the properties of ZrO2 thin films prepared in electron beam evaporation method

    Institute of Scientific and Technical Information of China (English)

    Dongping Zhang(张东平); Meiqiong Zhan(占美琼); Ming Fang(方明); Hongbo He(贺洪波); Jianda Shao(邵建达); Zhengxiu Fan(范正修)

    2004-01-01

    ZrO2 thin films were prepared in electron beam thermal evaporation method. And the deposition rate changed from 1.3 to 6.3 nm/s in our study. X-ray diffractometer and spectrophotometer were employed to characterize the films. X-ray diffraction (XRD) spectra pattern shows that films structure changed from amorphous to polycrystalline with deposition rate increasing. The results indicate that internal stresses of the films are compressive in most case. Thin films deposited in our study are inhomogeneous, and the inhomogeneity is enhanced with the deposition rate increasing.

  15. Direct growth of doping-density-controlled hexagonal graphene on SiO2 substrate by rapid-heating plasma CVD.

    Science.gov (United States)

    Kato, Toshiaki; Hatakeyama, Rikizo

    2012-10-23

    A transfer-free method for growing carrier-density-controlled graphene directly on a SiO(2) substrate has been realized for the first time by rapid-heating plasma chemical vapor deposition (RH-PCVD). Using this method, high-quality single-layer graphene sheets with a hexagonal domain can be selectively grown between a Ni film and a SiO(2) substrate. Systematic investigations reveal that the relatively thin Ni layer, rapid heating, and plasma CVD are critical to the success of this unique method of graphene growth. By applying this technique, an easy and scalable graphene-based field effect transistor (FET) fabrication is also demonstrated. The electrical transport type of the graphene-based FET can be precisely tuned by adjusting the NH(3) gas concentration during the RH-PCVD process.

  16. Methods of improvement of forecasting of development of mineral deposits' power supply

    Directory of Open Access Journals (Sweden)

    Alexander V. Putilov

    2015-03-01

    Full Text Available Mineral deposits (among which non-ferrous metals take a leading place are situated on the territory of our planet rather unevenly, and often in out-of-the-way places. Nuclear power (particularly, transportable nuclear power plants provides the new possibilities of power supply, which is very important for deposits' development. This article shares the economic aspects of forecasting in the field of power development (in particular, nuclear power on the basis of transportable nuclear power plants. Economic barriers of development of innovative nuclear technologies are considered on the example of transportable nuclear power plants. At the same time, there are given the ways of elimination of such barrier to development of this technology as methodical absence of investigation of a question of distribution of added cost between producers of innovative equipment and final product. Addition of new analytical tool (“business diagonal” is offered for a method of definition of economically efficient distribution of added cost (received as a result of introduction of innovative technologies between participants of production and consumption of atomic energy within the “economic cross” model. There is offered the order of use of method of cash flows discounting at calculations between nuclear market participants. Economic methods, offered in this article, may be used in forecasting of development of other energy technologies and introduction of prospective energy equipment.

  17. Methods of optimization of reactive sputtering conditions of Al target during AlN films deposition

    Directory of Open Access Journals (Sweden)

    Chodun Rafal

    2015-12-01

    Full Text Available Encouraged by recent studies and considering the well-documented problems occurring during AlN synthesis, we have chosen two diagnostic methods which would enable us to fully control the process of synthesis and characterize the synthesized aluminum nitride films. In our experiment we have compared the results coming from OES measurements of plasma and circulating power characteristics of the power supply with basic features of the deposited layers. The dual magnetron system operating in AC mode was used in our studies. Processes of aluminum target sputtering were carried out in an atmosphere of a mixture of argon and nitrogen. The plasma emission spectra were measured with the use of a monochromator device. Analyses were made by comparing the positions and intensities of spectral lines of the plasma components. The results obtained allowed us to characterize the sputtering process under various conditions of gas mixture compositions as well as power distribution more precisely, which is reported in this work. The measured spectra were related to the deposition rate, the structure morphology of the films and chemical composition. Our work proved that the use of plasma OES and circulating power measurements make possible to control the process of sputtering and synthesis of deposited films in situ.

  18. Imaging Quaternary glacial deposits and basement topography using the transient electromagnetic method for modeling aquifer environments

    Science.gov (United States)

    Simard, Patrick Tremblay; Chesnaux, Romain; Rouleau, Alain; Daigneault, Réal; Cousineau, Pierre A.; Roy, Denis W.; Lambert, Mélanie; Poirier, Brigitte; Poignant-Molina, Léo

    2015-08-01

    Aquifer formations along the northern shore of the Saint-Lawrence River in Quebec (Canada) mainly consist of glacial and coastal deposits of variable thickness overlying Precambrian bedrock. These deposits are important because they provide the main water supply for many communities. As part of a continuing project aimed at developing an inventory of the groundwater resources in the Charlevoix and Haute-Côte-Nord (CHCN) regions of the province of Quebec in Canada, the central loop transient electromagnetic (TEM) method was used to map the principal hydrogeological environments in these regions. One-dimensional smooth inversion models of the TEM soundings have been used to construct two-dimensional electrical resistivity sections, which provided images for hydrogeological validation. Electrical contour lines of aquifer environments were compared against available well logs and Quaternary surface maps in order to interpret TEM soundings. A calibration table was achieved to represent common deposits and basements. The calibration table was then exported throughout the CHCN region. This paper presents three case studies; one in the Forestville site, another in the Les Escoumins site and the other in the Saint-Urbain site. These sites were selected as targets for geophysical surveys because of the general lack of local direct hydrogeological data related to them.

  19. Fabrication of ZnO nanorod using spray-pyrolysis and chemical bath deposition method

    Energy Technology Data Exchange (ETDEWEB)

    Ramadhani, Muhammad F., E-mail: brian@tf.itb.ac.id; Pasaribu, Maruli A. H., E-mail: brian@tf.itb.ac.id; Yuliarto, Brian, E-mail: brian@tf.itb.ac.id; Nugraha, E-mail: brian@tf.itb.ac.id [Advanced Functional Materials Laboratory, Engineering Physics Department Faculty of Industrial Technology, Institut Teknologi Bandung (Indonesia)

    2014-02-24

    ZnO thin films with nanorod structure were deposited using Ultrasonic Spray Pyrolysis method for seed growth, and Chemical Bath Deposition (CBD) for nanorod growth. High purity Zn-hydrate and Urea are used to control Ph were dissolved in ethanol and aqua bidest in Ultrasonic Spray Pyrolysis process. Glass substrate was placed above the heater plate of reaction chamber, and subsequently sprayed with the range duration of 5, 10 and 20 minutes at the temperatures of 3500 C. As for the Chemical Bath Deposition, the glass substrate with ZnO seed on the surface was immerse to Zn-hydrate, HMTA (Hexa Methylene Tetra Amine) and deionized water solution for duration of 3, 5 and 7 hour and temperatures of 600 C, washed in distilled water, dried, and annealed at 3500 C for an hour. The characterization of samples was carried out to reveal the surface morphology using Scanning Electron Microscopy (SEM). From the data, the combination of 5 minutes of Ultrasonic Spray Pyrolysis process and 3 hour of CBD has showed the best structure of nanorod. Meanwhile the longer Spraying process and CBD yield the bigger nanorod structure that have been made, and it makes the films more dense which make the nanorod collide each other and as a result produce unsymetric nanorod structure.

  20. Roll-to-roll light directed electrophoretic deposition system and method

    Energy Technology Data Exchange (ETDEWEB)

    Pascall, Andrew J.; Kuntz, Joshua

    2017-06-06

    A roll-to-roll light directed electrophoretic deposition system and method advances a roll of a flexible electrode web substrate along a roll-to-roll process path, where a material source is positioned to provide on the flexible electrode web substrate a thin film colloidal dispersion of electrically charged colloidal material dispersed in a fluid. A counter electrode is also positioned to come in contact with the thin film colloidal dispersion opposite the flexible electrode web substrate, where one of the counter electrode and the flexible electrode web substrate is a photoconductive electrode. A voltage source is connected to produce an electric potential between the counter electrode and the flexible electrode web substrate to induce electrophoretic deposition on the flexible electrode web substrate when the photoconductive electrode is rendered conductive, and a patterned light source is arranged to illuminate the photoconductive electrode with a light pattern and render conductive illuminated areas of the photoconductive electrode so that a patterned deposit of the electrically charged colloidal material is formed on the flexible electrode web substrate.

  1. 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…

  2. Thermoelectric properties of CVD grown large area graphene

    Science.gov (United States)

    Sherehiy, Andriy; Jayasinghe, Ruwantha; Stallard, Robert; Sumanasekera, Gamini; Sidorov, Anton; Benjamin, Daniel; Jiang, Zhigang; Yu, Qingkai; Wu, Wei; Bao, Jiming; Liu, Zhihong; Pei, Steven; Chen, Yong

    2010-03-01

    The thermoelectric power (TEP) of CVD (Chemical Vapor Deposition) grown large area graphene transferred onto a Si/SiO2 substrate was measured by simply attaching two miniature thermocouples and a resistive heater. Availability of such large area graphene facilitates straight forward TEP measurement without the use of any microfabrication processes. All investigated graphene samples showed a positive TEP ˜ + 30 μV/K in ambient conditions and saturated at a negative value as low as ˜ -75 μV/K after vacuum-annealing at 500 K in a vacuum of ˜10-7 Torr. The observed p-type behavior under ambient conditions is attributed to the oxygen doping, while the n-type behavior under degassed conditions is due to electron doping from SiO2 surface states. It was observed that the sign of the TEP switched from negative to positive for the degassed graphene when exposed to acceptor gases. Conversely, the TEP of vacuum-annealed graphene exposed to the donor gases became even more negative than the TEP of vacuum-annealed sample.

  3. A Fast CVD Diamond Beam Loss Monitor for LHC

    CERN Document Server

    Griesmayer, E; Dobos, D; Effinger, E; Pernegger, H

    2011-01-01

    Chemical Vapour Deposition (CVD) diamond detectors were installed in the collimation area of the CERN LHC to study their feasibility as Fast Beam Loss Monitors in a high-radiation environment. The detectors were configured with a fast, radiation-hard pre-amplifier with a bandwidth of 2 GHz. The readout was via an oscilloscope with a bandwidth of 1 GHz and a sampling rate of 5 GSPS. Despite the 250 m cable run from the detectors to the oscilloscope, single MIPs were resolved with a 2 ns rise time, a pulse width of 10 ns and a time resolution of less than 1 ns. Two modes of operation were applied. For the analysis of unexpected beam aborts, the loss profile was recorded in a 1 ms buffer and, for nominal operation, the histogram of the time structure of the losses was recorded in synchronism with the LHC period of 89.2 μs. Measurements during the LHC start-up (February to December 2010) are presented. The Diamond Monitors gave an unprecedented insight into the time structure of the beam losses resolving the 400...

  4. Rare genetic variants associated with early onset CVD

    NARCIS (Netherlands)

    Maiwald, S.

    2015-01-01

    Cardiovascular disease (CVD) is the major cause of morbidity and mortality in Western societies. CVD is mainly triggered by atherosclerosis. A combination of lipid accumulation, inflammation at the vessel wall and thrombotic reactions are underlying its pathobiology. Despite improvements in the ther

  5. Prevention: Reducing the risk of CVD in patients with periodontitis.

    Science.gov (United States)

    Genco, Robert J; Van Dyke, Thomas E

    2010-09-01

    The association between periodontitis and other chronic diseases, such as cardiovascular disease (CVD) and type 2 diabetes mellitus, could be related to systemic inflammation initiated by a local inflammatory challenge. Oliveira et al. have added lack of oral hygiene, and its link with systemic inflammation, to the spectrum of risk factors for CVD.

  6. Optical Properties of One-Dimensional Structured GaN:Mn Fabricated by a Chemical Vapor Deposition Method

    Directory of Open Access Journals (Sweden)

    Sang-Wook Ui

    2013-01-01

    Full Text Available Group III nitride semiconductors with direct band gaps have recently become increasingly important in optoelectronics and microelectronics applications due to their direct band gaps, which cover the whole visible spectrum and a large part of the UV range. Major developments in wide band gap III–V nitride semiconductors have recently led to the commercial production of high-temperature, high-power electronic devices, light-emitting diodes (LEDs, and laser diodes (LDs. In this study, GaN nanowires were grown on horizontal reactors by chemical vapor deposition (CVD employing a vapor-solid mechanism. Many studies have described how to control the diameters of wires in the liquid phase catalytic process, but one-dimensional nanostructures, which are grown using a noncatalytic process, are relatively unexplored due to the challenge of producing high-quality synthetic materials of controlled size. However, vapor-solid mechanisms to make synthesized nanowires are simple to implement. We obtained results from GaN nanostructures that were a preferential c-axis orientation from the substrate. The morphology and crystallinity of the GaN nanowires were characterized by field-emission scanning electron microscopy and X-ray diffraction. The chemical compositions of GaN with Mn were analyzed by energy dispersive X-ray spectroscopy. Optical properties were investigated using photo luminescence and cathode-luminescence measurements.

  7. Eight-term cyclic phosphites as coke deposit inhibitors and a method for producing them

    Energy Technology Data Exchange (ETDEWEB)

    Vershinin, P.V.; Chebotareva, E.G.; Kadyrova, V.Kh.; Kirpichnikov, P.A.; Pozdnev, V.V.; Vershinin, Yu.P.; Zharkova, V.M.

    1982-01-01

    It is proposed that a eight-term cyclic phosphite formula be used where R = methyl, R' = tertiary-butyl or alpha-methylcyclohexyl, R'' = tertiary-butyl, R''' = hydrogen, methyl, tertiary-butyle, bromine, X = methylene and sulfur as coke deposit inhibitors in the pyrolysis of petroleum raw materials. A method for producing the eight-term cyclic phosphite formula is proposed where a cyclic chlorophosphite formula interacts with a phenol formula in a medium of polar aprotic solvent using a base at 80-100 degrees.

  8. Incorporation of precious metal nanoparticles into various aerogels by different supercritical deposition methods

    Science.gov (United States)

    Saquing, Carl D.

    2005-11-01

    One major hurdle in nanoparticle fabrication is the difficulty in controlling size, distribution and concentration. Conventional methods in nanoparticle formation require high temperatures which lead to particle agglomeration and size broadening, or involve substantial amount of organic solvents. A clean route to supported-nanoparticles fabrication was investigated using various supercritical (SC) based deposition methods. The SC deposition involves the organometallic precursor (OP) (dimethyl(1,5-cyclooctadiene)platinum(II)[CODPtMe 2] or bis(2,2,6,6-tetramethyl-3,5-heptanedionato) (1,5-cyclooctadiene) ruthenium(II)) dissolution in SC fluid and contacting this solution with a substrate. The OP is adsorbed and subsequent reduction of the OP-impregnated substrate produces metal/substrate composites. The various methods were: (1) thermal reduction at atmospheric pressure in an inert atmosphere; (2) thermal reduction in SC carbon dioxide (scCO2); (3) chemical reduction in scCO2 with H2; and (4) chemical reduction at atmospheric pressure with H2. The synthesis of resorcinol-formaldehyde aerogels (RFAs) and carbon aerogels (CAs) was also studied and used as substrates (along with commercial silica aerogels (SAs)) in the SC deposition. The surface area, pore properties, and density of these aerogels were evaluated and the effects of reactant concentration, pyrolysis and SC deposition on these properties were determined. Using a static method, the adsorption isotherms of CODPtMe2 in scCO2 on two CAs with different pore sizes were measured at 28 MPa and 80°C to determine the maximum metal loading and the effect of pore properties on adsorption and to examine the interactions between the three components. The isotherms could be represented by the Langmuir model and the adsorption data indicated a strong CODPtMe2-CA interaction and that almost all the preexistent micropore area was covered with CODPtMe 2 molecules even at adsorption lower than the maximum capacity. The

  9. In Situ Coupling of Ultrasound to Electro- and Photo-Deposition Methods for Materials Synthesis.

    Science.gov (United States)

    Magdziarz, Agnieszka; Colmenares, Juan C

    2017-01-31

    This short review provides the current state-of-the-art of in situ coupling of ultrasound to chemical deposition methods. A synergetic action of the ultrasound and light radiation or electrical fields may result in new powerful methodologies, and these include sonophotodeposition and sonoelectrodeposition processes. The effect of ultrasound is explained on the base of different physical mechanisms emerging from cavitation phenomenon. Some possible mechanisms of the interactions between ultrasound and photochemical and electrochemical processes are discussed here. The application of sonophotodeposition and sonoelectrodeposition as green energy sources in the syntheses of different nanomaterials is also reviewed.

  10. Buffer layer engineering on graphene via various oxidation methods for atomic layer deposition

    Science.gov (United States)

    Takahashi, Nobuaki; Nagashio, Kosuke

    2016-12-01

    The integration of a high-k oxide on graphene using atomic layer deposition requires an electrically reliable buffer layer. In this study, Y was selected as the buffer layer due to its highest oxidation ability among the rare-earth elements, and various oxidation methods (atmospheric, and high-pressure O2 and ozone annealing) were applied to the Y metal buffer layer. By optimizing the oxidation conditions of the top-gate insulator, we successfully improved the capacitance of the top gate Y2O3 insulator and demonstrated a large I on/I off ratio for bilayer graphene under an external electric field.

  11. Synthesis and characterization of gold nanoparticles supported on zinc oxide via the deposition-precipitation method

    OpenAIRE

    Yazid, Hanani; Adnan, Rohana; HAMID, Shafida Abdul; Farrukh, Muhammad Akhyar

    2010-01-01

    Gold nanoparticles supported on zinc oxide nanoparticles were synthesized at several pH levels via the deposition-precipitation (DP) method. The effects of pH on gold loading, particle size, and particle size distribution on the support were studied at the iso-electric point (IEP) as well as below and above the IEP of ZnO. The addition of the support significantly changed the pH of the solution. The effects of adjusting the pH before and after the addition of the support into the gol...

  12. Methods of three-dimensional electrophoretic deposition for ceramic and cermet applications and systems thereof

    Energy Technology Data Exchange (ETDEWEB)

    Rose, Klint Aaron; Kuntz, Joshua D.; Worsley, Marcus

    2016-09-27

    A ceramic, metal, or cermet according to one embodiment includes a first layer having a gradient in composition, microstructure and/or density in an x-y plane oriented parallel to a plane of deposition of the first layer. A ceramic according to another embodiment includes a plurality of layers comprising particles of a non-cubic material, wherein each layer is characterized by the particles of the non-cubic material being aligned in a common direction. Additional products and methods are also disclosed.

  13. In Situ Coupling of Ultrasound to Electro- and Photo-Deposition Methods for Materials Synthesis

    Directory of Open Access Journals (Sweden)

    Agnieszka Magdziarz

    2017-01-01

    Full Text Available This short review provides the current state-of-the-art of in situ coupling of ultrasound to chemical deposition methods. A synergetic action of the ultrasound and light radiation or electrical fields may result in new powerful methodologies, and these include sonophotodeposition and sonoelectrodeposition processes. The effect of ultrasound is explained on the base of different physical mechanisms emerging from cavitation phenomenon. Some possible mechanisms of the interactions between ultrasound and photochemical and electrochemical processes are discussed here. The application of sonophotodeposition and sonoelectrodeposition as green energy sources in the syntheses of different nanomaterials is also reviewed.

  14. Dependence of ZnO-based dye-sensitized solar cell characteristics on the layer deposition method

    Indian Academy of Sciences (India)

    Anca Dumbrava; Gabriel Prodan; Adrian Georgescu; Florin Moscalu

    2015-02-01

    The selection of a proper method for the semiconductor layer deposition is an important requirement towards a high efficiency for dye-sensitized solar cells (DSSCs). We compared three techniques for deposition of the semiconductor thin layer in ZnO-based DSSCs, in order to determine the dependence between the deposition method, the ZnO film properties and finally the DSSCs characteristics. For this purpose, we varied the method used for deposition of the semiconductor film and we replaced ZnO with Al-doped ZnO. The nanostructured films morphology was analysed by transmission electron microscopy, high-resolution transmission electron microscopy and selected area electron diffraction. The optical properties were examined by UV–visible spectroscopy and the bandgap energies were calculated using the Tauc equation. The higher fill factor value was registered for DSSCs based on the ZnO film obtained by electrochemical method, but the higher efficiency was registered for doctorblading method.

  15. Handbook of chemical vapor deposition principles, technology and applications

    CERN Document Server

    Pierson, Hugh O

    1999-01-01

    Turn to this new second edition for an understanding of the latest advances in the chemical vapor deposition (CVD) process. CVD technology has recently grown at a rapid rate, and the number and scope of its applications and their impact on the market have increased considerably. The market is now estimated to be at least double that of a mere seven years ago when the first edition of this book was published. The second edition is an update with a considerably expanded and revised scope. Plasma CVD and metallo-organic CVD are two major factors in this rapid growth. Readers will find the latest

  16. The impact of individualised cardiovascular disease (CVD risk estimates and lifestyle advice on physical activity in individuals at high risk of CVD: a pilot 2 × 2 factorial understanding risk trial

    Directory of Open Access Journals (Sweden)

    Griffin Simon J

    2008-07-01

    Full Text Available Abstract Background There is currently much interest in encouraging individuals to increase physical activity in order to reduce CVD risk. This study has been designed to determine if personalised CVD risk appreciation can increase physical activity in adults at high risk of CVD. Methods/Design In a 2 × 2 factorial design participants are allocated at random to a personalised 10-year CVD risk estimate or numerical CVD risk factor values (systolic blood pressure, LDL cholesterol and fasting glucose and, simultaneously, to receive a brief lifestyle advice intervention targeting physical activity, diet and smoking cessation or not. We aim to recruit 200 participants from Oxfordshire primary care practices. Eligibility criteria include adults age 40–70 years, estimated 10-year CVD risk ≥20%, ability to read and write English, no known CVD and no physical disability or other condition reducing the ability to walk. Primary outcome is physical activity measured by ActiGraph accelerometer with biochemical, anthropometrical and psychological measures as additional outcomes. Primary analysis is between group physical activity differences at one month powered to detect a difference of 30,000 total counts per day of physical activity between the groups. Additional analyses will seek to further elucidate the relationship between the provision of risk information, and intention to change behaviour and to determine the impact of both interventions on clinical and anthropometrical measures including fasting and 2 hour plasma glucose, fructosamine, serum cotinine, plasma vitamin C, body fat percentage and blood pressure. Discussion This is a pilot trial seeking to demonstrate in a real world setting, proof of principal that provision of personalised risk information can contribute to behaviour changes aimed at reducing CVD risk. This study will increase our understanding of the links between the provision of risk information and behaviour change and if

  17. Development of long Y-123 coated conductors by ion-beam-assisted-deposition and the pulsed-laser-deposition method

    Energy Technology Data Exchange (ETDEWEB)

    Iijima, Yasuhiro; Kakimoto, Kazuomi; Sutoh, Yasunori; Ajimura, Shoji; Saitoh, Takashi [Material Technology Laboratory, Fujikura Ltd, 1-5-1, Kiba, Koto-ku, Tokyo 135-8512 (Japan)

    2004-05-01

    100 m class Y-123 coated conductors were produced by using reel-to-reel vacuum ion-beam-assisted-deposition (IBAD) and pulsed-laser-deposition (PLD) apparatuses. 100 m long IBAD-Gd{sub 2}Zr{sub 2}O{sub 7} template films were uniformly and routinely obtained on non-textured Ni-alloy tapes, with FWHM of {delta}{phi} below 10 deg. Y-123 films with FWHM of {delta}{phi} below 7 deg. were formed on them by PLD. End-to-end I{sub c} of 38 A and J{sub c} of 0.76 MA cm{sup -2} (77 K, self-field) were obtained in a 100 m long sample. For further texture improvement, secondary buffer layers of CeO{sub 2} and Gd{sub 2}Zr{sub 2}O{sub 7} grown by PLD on IBAD-Gd{sub 2}Zr{sub 2}O{sub 7} template films were studied. {delta}{phi} of 3 deg. and J{sub c} of 2.9 MA cm{sup -2} were obtained in a 0.1 m long Y-123 film and J{sub c} improved to 1.6 MA cm{sup -2} for an 80 m long Y-123 tape by using the CeO{sub 2} buffer layers.

  18. Novel photochemical vapor deposition reactor for amorphous silicon solar cell deposition

    Science.gov (United States)

    Rocheleau, Richard E.; Hegedus, Steven S.; Buchanan, Wayne A.; Jackson, Scott C.

    1987-07-01

    A novel photochemical vapor deposition (photo-CVD) reactor having a flexible ultraviolet-transparent Teflon curtain and a secondary gas flow to eliminate deposition on the window has been used to deposit amorphous silicon films and p-i-n solar cells. The background levels of atmospheric contaminants (H2O, CO2, N2) depend strongly on the vacuum procedures but not on the presence of a Teflon curtain in the reactor. Intrinsic films with a midgap density of states of 3×1015 eV-1 cm-3 and all-photo-CVD pin solar cells with efficiencies of 8.5% have been deposited.

  19. Design and implementation of a novel portable atomic layer deposition/chemical vapor deposition hybrid reactor.

    Science.gov (United States)

    Selvaraj, Sathees Kannan; Jursich, Gregory; Takoudis, Christos G

    2013-09-01

    We report the development of a novel portable atomic layer deposition chemical vapor deposition (ALD/CVD) hybrid reactor setup. Unique feature of this reactor is the use of ALD/CVD mode in a single portable deposition system to fabricate multi-layer thin films over a broad range from "bulk-like" multi-micrometer to nanometer atomic dimensions. The precursor delivery system and control-architecture are designed so that continuous reactant flows for CVD and cyclic pulsating flows for ALD mode are facilitated. A custom-written LabVIEW program controls the valve sequencing to allow synthesis of different kinds of film structures under either ALD or CVD mode or both. The entire reactor setup weighs less than 40 lb and has a relatively small footprint of 8 × 9 in., making it compact and easy for transportation. The reactor is tested in the ALD mode with titanium oxide (TiO2) ALD using tetrakis(diethylamino)titanium and water vapor. The resulting growth rate of 0.04 nm/cycle and purity of the films are in good agreement with literature values. The ALD/CVD hybrid mode is demonstrated with ALD of TiO2 and CVD of tin oxide (SnOx). Transmission electron microscopy images of the resulting films confirm the formation of successive distinct TiO2-ALD and SnO(x)-CVD layers.

  20. Design and implementation of a novel portable atomic layer deposition/chemical vapor deposition hybrid reactor

    Science.gov (United States)

    Selvaraj, Sathees Kannan; Jursich, Gregory; Takoudis, Christos G.

    2013-09-01

    We report the development of a novel portable atomic layer deposition chemical vapor deposition (ALD/CVD) hybrid reactor setup. Unique feature of this reactor is the use of ALD/CVD mode in a single portable deposition system to fabricate multi-layer thin films over a broad range from "bulk-like" multi-micrometer to nanometer atomic dimensions. The precursor delivery system and control-architecture are designed so that continuous reactant flows for CVD and cyclic pulsating flows for ALD mode are facilitated. A custom-written LabVIEW program controls the valve sequencing to allow synthesis of different kinds of film structures under either ALD or CVD mode or both. The entire reactor setup weighs less than 40 lb and has a relatively small footprint of 8 × 9 in., making it compact and easy for transportation. The reactor is tested in the ALD mode with titanium oxide (TiO2) ALD using tetrakis(diethylamino)titanium and water vapor. The resulting growth rate of 0.04 nm/cycle and purity of the films are in good agreement with literature values. The ALD/CVD hybrid mode is demonstrated with ALD of TiO2 and CVD of tin oxide (SnOx). Transmission electron microscopy images of the resulting films confirm the formation of successive distinct TiO2-ALD and SnOx-CVD layers.

  1. Catalytic Synthesis of Substrate-Free, Aligned and Tailored High Aspect Ratio Multiwall Carbon Nanotubes in an Ultrasonic Atomization Head CVD Reactor

    Directory of Open Access Journals (Sweden)

    Fahad Ali Rabbani

    2016-01-01

    Full Text Available Chemical vapor deposition (CVD method has proven its benchmark, over other methods, for the production of different types of carbon nanotubes (CNT on commercial and lab scale. In this study, an injection vertical CVD reactor fitted with an ultrasonic atomization head was used in a pilot-plant scale (height 274 cm, radius 25 cm for semicontinuous production of multiwall carbon nanotubes (MWCNTs. p-Xylene was used as a hydrocarbon precursor in which ferrocene was dissolved and provided the cracking catalyst. Atomization of the feed solution resulted in full and even dispersion of the catalytic solution. This dispersion led to the production of high aspect ratio MWCNTs (ranging from 8,000 to 12,000 at 850°C. Different experimental parameters affecting the quality and quantity of the produced CNTs were investigated. These included temperature, reaction time, and flow rate of the reaction and carrier gases. Different properties of the produced CNTs were characterized using SEM and TEM, while TGA was used to evaluate their purity. Specific surface area of selected samples was calculated by BET.

  2. Synthesis of γ-WO{sub 3} thin films by hot wire-CVD and investigation of its humidity sensing properties

    Energy Technology Data Exchange (ETDEWEB)

    Jadkar, Vijaya; Waykar, Ravindra; Jadhavar, Ashok [School of Energy Studies, Savitribai Phule Pune University, Pune 411 007 (India); Pawbake, Amit [School of Energy Studies, Savitribai Phule Pune University, Pune 411 007 (India); Physical and Material Chemistry Division, National Chemical Laboratory, Pune 411 008 (India); Date, Abhijit [School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, Plenty Road, Bundoora, Melbourne VIC 3083 (Australia); Late, Dattatray [Physical and Material Chemistry Division, National Chemical Laboratory, Pune 411 008 (India); Pathan, Habib; Gosavi, Suresh; Jadkar, Sandesh [Department of Physics, Savitribai Phule Pune University, Pune 411 007 (India)

    2017-05-15

    In this study, monoclinic tungsten oxide (γ-WO{sub 3}) have been grown in a single step using HW-CVD method by resistively heating W filaments in a constant O{sub 2} pressure. The formation of γ-WO{sub 3} was confirmed using low angle-XRD and Raman spectroscopy analysis. Low angle-XRD analysis revealed that as-deposited WO{sub 3} film are highly crystalline and the crystallites have preferred orientation along the (002) direction. HRTEM analysis and SAED pattern also show the highly crystalline nature of WO{sub 3} with d spacing of ∝ 0.38 nm, having an orientation along the (002) direction. Surface topography investigated by SEM analysis shows the formation of a uniform and homogeneous cauliflower like morphology throughout the substrate surface without flaws and cracks. A humidity sensing device incorporating WO{sub 3} is also fabricated, which shows a maximum humidity sensitivity factor of ∝ 3954% along with a response time of ∝14 s and a recovery time of ∝25 s. The obtained results demonstrate that it is possible to synthesize WO{sub 3} in a single step by HW-CVD method and to fabricate a humidity sensor by using it. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Chemical vapor deposition of ceramic coatings on metals and ceramic fibers

    Science.gov (United States)

    Nable, Jun Co

    2005-07-01

    The research presented in this study consists of two major parts. The first part is about the development of ceramic coatings on metals by chemical vapor deposition (CVD) and metal-organic chemical vapor deposition (MOCVD). Ceramics such as Al2O3 and Cr2O3, are used as protective coatings for materials used at elevated temperatures (>700°C). These metal oxides either exhibit oxidation resistance or have been used as environmental bond coats. Conventional methods of coating by chemical vapor deposition requires deposition temperatures of >950°C which could damage the substrate material during the coating process. Lower deposition temperatures (400 to 600°C) by MOCVD of these metal oxides were successful on Ni metal substrates. Surface modification such as pre-oxidation and etching were also investigated. In addition, a novel approach for the CVD of TiN on metals was developed. This new approach utilizes ambient pressure conditions which lead to deposition temperatures of 800°C or lower compared to conventional CVD of TiN at 1000°C. Titanium nitride can be used as an abrasive and wear coating on cutting and grinding tools. This nitride can also serve as a diffusion coating in metals. The second major part of this research involves the synthesis of interfacial coatings on ceramic reinforcing fibers for ceramic matrix composites. Aluminum and chromium oxides were deposited onto SiC, and Al2O3-SiO 2 fibers by MOCVD. The effects of the interface coatings on the tensile strength of ceramic fibers are also discussed. New duplex interface coatings consisting of BN or TiN together with Al2O3 or ZrO 2 were also successfully deposited and evaluated on SiC fibers.

  4. A new interpolation method to model thickness, isopachs, extent, and volume of tephra fall deposits

    Science.gov (United States)

    Yang, Qingyuan; Bursik, Marcus

    2016-10-01

    Tephra thickness distribution is the primary piece of information used to reconstruct the histories of past explosive volcanic eruptions. We present a method for modeling tephra thickness with less subjectivity than is the case with hand-drawn isopachs, the current, most frequently used method. The algorithm separates the thickness of a tephra fall deposit into a trend and local variations and models them separately using segmented linear regression and ordinary kriging. The distance to the source vent and downwind distance are used to characterize the trend model. The algorithm is applied to thickness datasets for the Fogo Member A and North Mono Bed 1 tephras. Simulations on subsets of data and cross-validation are implemented to test the effectiveness of the algorithm in the construction of the trend model and the model of local variations. The results indicate that model isopach maps and volume estimations are consistent with previous studies and point to some inconsistencies in hand-drawn maps and their interpretation. The most striking feature noticed in hand-drawn mapping is a lack of adherence to the data in drawing isopachs locally. Since the model assumes a stable wind field, divergences from the predicted decrease in thickness with distance are readily noticed. Hence, wind direction, although weak in the case of Fogo A, was not unidirectional during deposition. A combination of the isopach algorithm with a new, data transformation can be used to estimate the extent of fall deposits. A limitation of the algorithm is that one must estimate "by hand" the wind direction based on the thickness data.

  5. Controlling of morphology and electrocatalytic properties of cobalt oxide nanostructures prepared by potentiodynamic deposition method

    Energy Technology Data Exchange (ETDEWEB)

    Hallaj, Rahman [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Akhtari, Keivan [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Research Center for Nanotechnology, University of Kurdistan, P.O.Box 416, Sanandaj (Iran, Islamic Republic of); Salimi, Abdollah, E-mail: absalimi@uok.ac.ir [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Research Center for Nanotechnology, University of Kurdistan, P.O.Box 416, Sanandaj (Iran, Islamic Republic of); Soltanian, Saied [Department of Physics, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of)

    2013-07-01

    Electrodeposited cobalt oxide nanostructures were prepared by Repetitive Triangular Potential Scans (RTPS) as a simple, remarkably fast and scalable potentiodynamic method. Electrochemical deposition of cobalt oxide nanostructures onto GC electrode was performed from aqueous Co(NO{sub 3}){sub 2}, (pH 6) solution using cyclic voltammetry method. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to characterize the morphology of fabricated nanostructures. The evaluation of electrochemical properties of deposited films was performed using cyclic voltametry (CV) and impedance spectroscopy (IS) techniques. The analysis of the experimental data clearly showed that the variations of potential scanning ranges during deposition process have drastic effects on the geometry, chemical structure and particle size of cobalt oxide nanoparticles. In addition, the electrochemical and electrocatalytic properties of prepared nanostructures can be controlled through applying different potential windows in electrodeposition process. The imaging and voltammetric studies suggested to the existence of at least three different shapes of cobalt-oxide nanostructures in various potential windows applied for electrodeposition. With enlarging the applied potential window, the spherical-like cobalt oxide nanoparticles with particles sizes about 30–50 nm changed to the grain-like structures (30 nm × 80 nm) and then to the worm-like cobalt oxide nanostructures with 30 nm diameter and 200–400 nm in length. Furthermore, the roughness of the prepared nanostructures increased with increasing positive potential window. The GC electrodes modified with cobalt oxide nanostructures shows excellent electrocatalytic activity toward H{sub 2}O{sub 2} and As (III) oxidation. The electrocatalytic activity of cobalt oxide nanostructures prepared at more positive potential window toward hydrogen peroxide oxidation was increased, while for As(III) oxidation the electrocatalytic

  6. The computer application for the opal breccia deposit performance: the discreet interpolation or the finite diferences method

    OpenAIRE

    2003-01-01

    The application of discreet interpolation or the finite differences methods for opal breccia deposit. The performance is carried out by computer application and graphical presentation for quartz and aluminium oxide.

  7. New methods of controlled monolayer-to-multilayer deposition of Pt for designing electrocatalysts at an atomic level

    Directory of Open Access Journals (Sweden)

    J. X. WANG

    2001-12-01

    Full Text Available Two new methods for monolayer-to-multileyer Pt deposition are presented. One involves Pt deposition by the replacement of an UPD metal monolayer on an electrode surface and the other the spontaneous deposition of Pt on Ru. The first method, exemplified by the replacement of a Cu monolayer on a Au(111 surface, occurs as a spontaneous irreversible redox reaction in which the Cu monolayer is oxidized by Pt cations, which are reduced and simultaneously deposited. The second method is illustrated by the deposition of Pt on a Ru(0001 surface and on carbon-supported Ru nanoparticles. This deposition takes place upon immersion of a UHV-prepared Ru(0001 crystal or Ru nanoparticles, reduced in H2, in a solution containing PtCl62- ions. The oxidation of Ru to RuOH by a local cell mechanism appears to be coupled with Pt deposition. This method facilitates the design of active Pt-Ru catalysts with ultimately low Pt loadings. Only a quarter of a monolayer of Pt on Ru nanoparticles yields an electrocatalyst with higher activity and CO tolerance for H2/CO oxidation than commercial Pt-Ru alloy electrocatalysts with considerably higher Pt loadings.

  8. System and method for the mitigation of paraffin wax deposition from crude oil by using ultrasonic waves

    Science.gov (United States)

    Towler, Brian F.

    2007-09-04

    A method for mitigating the deposition of wax on production tubing walls. The method comprises positioning at least one ultrasonic frequency generating device adjacent the production tubing walls and producing at least one ultrasonic frequency thereby disintegrating the wax and inhibiting the wax from attaching to the production tubing walls. A system for mitigating the deposition of wax on production tubing walls is also provided.

  9. Fabrication of Ultrasensitive Field-Effect Transistor DNA Biosensors by a Directional Transfer Technique Based on CVD-Grown Graphene.

    Science.gov (United States)

    Zheng, Chao; Huang, Le; Zhang, Hong; Sun, Zhongyue; Zhang, Zhiyong; Zhang, Guo-Jun

    2015-08-12

    Most graphene field-effect transistor (G-FET) biosensors are fabricated through a routine process, in which graphene is transferred onto a Si/SiO2 substrate and then devices are subsequently produced by micromanufacture processes. However, such a fabrication approach can introduce contamination onto the graphene surface during the lithographic process, resulting in interference for the subsequent biosensing. In this work, we have developed a novel directional transfer technique to fabricate G-FET biosensors based on chemical-vapor-deposition- (CVD-) grown single-layer graphene (SLG) and applied this biosensor for the sensitive detection of DNA. A FET device with six individual array sensors was first fabricated, and SLG obtained by the CVD-growth method was transferred onto the sensor surface in a directional manner. Afterward, peptide nucleic acid (PNA) was covalently immobilized on the graphene surface, and DNA detection was realized by applying specific target DNA to the PNA-functionalized G-FET biosensor. The developed G-FET biosensor was able to detect target DNA at concentrations as low as 10 fM, which is 1 order of magnitude lower than those reported in a previous work. In addition, the biosensor was capable of distinguishing the complementary DNA from one-base-mismatched DNA and noncomplementary DNA. The directional transfer technique for the fabrication of G-FET biosensors is simple, and the as-constructed G-FET DNA biosensor shows ultrasensitivity and high specificity, indicating its potential application in disease diagnostics as a point-of-care tool.

  10. The Effect of Annealing at 1500 C on Migration and Release of Ion Implanted Silver in CVD Silicon Carbide

    Energy Technology Data Exchange (ETDEWEB)

    HJ MacLean; RG Ballinger; LE Kolaya; SA Simonson; N Lewis; M Hanson

    2004-10-07

    The transport of silver in CVD {beta}-SiC has been studied using ion implantation. Silver ions were implanted in {beta}-SiC using the ATLAS accelerator facility at the Argonne National Laboratory. Ion beams with energies of 93 and 161 MeV were used to achieve deposition with peak concentrations at depths of approximately 9 and 13 {micro}m, respectively. As-implanted samples were then annealed at 1500 C for 210 or 480 hours. XPS, SEM, TEM, STEM, and optical methods were used to analyze the material before and after annealing. Silver concentration profiles were determined using XPS before and after annealing. STEM and SEM equipped with quantitative chemical analysis capability were used to more fully characterize the location and morphology of the silver before and after annealing. The results show that, within the uncertainty of measurement techniques, there is no silver migration, via either inter- or intragrannular paths, for the times and temperature studied. Additionally, the silver was observed to phase separate within the SiC after annealing. The irradiation damage from the implantation process resulted in a three-layer morphology in the as-implanted condition: (1) a layer of unaltered SiC, followed by (2) a layer of crystallized SiC, followed by (3) an amorphized layer which contained essentially all of the implanted silver. After annealing the layer structure changed. Layer 1 was unaltered. The grains in layer 2 recrystallized to form an epitaxial (columnar) layer. Layer 3 recrystallized to form a fine grain equiaxed layer. The results of this work do not support the long held assumption that silver release from CVD SiC, used for gas-reactor coated particle fuel, is dominated by grain boundary diffusion.

  11. Raman modes in transferred bilayer CVD graphene

    Directory of Open Access Journals (Sweden)

    Niilisk Ahti

    2015-01-01

    Full Text Available A systematic experimental Raman spectroscopic study of twisted bilayer graphene (tBLG domains localized inside wide-area single layer graphene (SLG produced by low-pressure CVD on Cu foil and transferred onto SiO2/Si substrate has been performed. According to the Raman characterization the tBLG domains had a great variety of twisting angles θ between the bottom and top graphene layers (6° < θ < 25°. The twisting angle θ was estimated from the spectral position of the rotating R and R' modes in the Raman spectrum.Under G band resonance conditions the breathing mode ZO' with a frequency of 95- 97 cm−1 was detected, and a breathing mode ZO was found in the spectra between 804 cm−1 and 836 cm−1, its position depending on the twisting angle θ. An almost linear relationship was found between the frequencies ωZO and ωR. Also a few other spectral peculiarities were found, e.g. a high-energy excitation of the G band resonance, the 2G overtone appearing at 3170-3180 cm−1 by the G band resonance, revealing a linear dispersion of 80 cm−1/eV of the 2D band in tBLG

  12. Calcium phosphate/porous silicon biocomposites prepared by cyclic deposition methods: Spin coating vs electrochemical activation

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Montelongo, J., E-mail: jacobo.hernandez@uam.es [Departamento de Física Aplicada, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Gallach, D.; Naveas, N.; Torres-Costa, V. [Departamento de Física Aplicada, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Climent-Font, A. [Departamento de Física Aplicada, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Centro de Microanálisis de Materiales (CMAM), Universidad Autónoma de Madrid, Madrid 28049 (Spain); García-Ruiz, J.P. [Departamento de Biología Molecular, Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049 (Spain); Manso-Silvan, M. [Departamento de Física Aplicada, Universidad Autónoma de Madrid, 28049 Madrid (Spain)

    2014-01-01

    Porous silicon (PSi) provides an excellent platform for bioengineering applications due to its biocompatibility, biodegradability, and bioresorbability. However, to promote its application as bone engineering scaffold, deposition of calcium phosphate (CaP) ceramics in its hydroxyapatite (HAP) phase is in progress. In that sense, this work focuses on the synthesis of CaP/PSi composites by means of two different techniques for CaP deposition on PSi: Cyclic Spin Coating (CSC) and Cyclic Electrochemical Activation (CEA). Both techniques CSC and CEA consisted on alternate Ca and P deposition steps on PSi. Each technique produced specific morphologies and CaP phases using the same independent Ca and P stem-solutions at neutral pH and at room temperature. The brushite (BRU) phase was favored with the CSC technique and the hydroxyapatite (HAP) phase was better synthesized using the CEA technique. Analyses by elastic backscattering spectroscopy (EBS) on CaP/PSi structures synthesized by CEA supported that, by controlling the CEA parameters, an HAP coating with the required Ca/P atomic ratio of 1.67 can be promoted. Biocompatibility was evaluated by bone-derived progenitor cells, which grew onto CaP/PSi prepared by CSC technique with a long-shaped actin cytoskeleton. The density of adhered cells was higher on CaP/PSi prepared by CEA, where cells presented a normal morphological appearance and active mitosis. These results can be used for the design and optimization of CaP/PSi composites with enhanced biocompatibility for bone-tissue engineering. - Highlights: • Proposed cyclic methods produce specific morphologies and CaP phases in biocomposites. • The brushite phase is favored in the biocomposite produced by Cyclic Spin Coating. • The hydroxyapatite phase is favored in the biocomposite produced by Cyclic Electrochemical Activation. • The Ca/P atomic ratio of hydroxyapatite was validated by elastic backscattering spectroscopy. • Cells grown showed morphological and

  13. Randschicht- und durchgreifendes Härten von 42CrMo4 nach CVD-Beschichtung

    DEFF Research Database (Denmark)

    Pantleon, Karen; Kessler, Olaf; Hoffmann, Franz

    1999-01-01

    the properties of steel substrates ready for operation. Bulk hardening and induction surface hardening as two different post-deposition heat treatments are applied on TiN-coated 42CrMo4 (AISI 4140) substrates. The results show great advantages of induction surface hardening because only low distortion appear......The properties of hard coatings deposited using CVD-processes are usually excellent. However, high deposition temperatures may negativelly influence the properties of the steel substrates, especially in the case of low alloyed steels. Therefore, a subsequent heat treatment is necessary to restore...... and the properties of the steel substrates are improved without loosing good coating properties. Thereby, the properties of the steel substrates can be influenced by the parameters of induction heating in a wide range....

  14. Aluminum and aluminum/silicon coatings on ferritic steels by CVD-FBR technology

    Energy Technology Data Exchange (ETDEWEB)

    Perez, F.J. [Grupo de Investigacion de Ingenieria de Superficies, Departamento de Ciencia de los Materiales, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, 28040 Madrid (Spain)]. E-mail: fjperez@quim.ucm.es; Hierro, M.P. [Grupo de Investigacion de Ingenieria de Superficies, Departamento de Ciencia de los Materiales, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, 28040 Madrid (Spain); Trilleros, J.A. [Grupo de Investigacion de Ingenieria de Superficies, Departamento de Ciencia de los Materiales, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, 28040 Madrid (Spain); Carpintero, M.C. [Grupo de Investigacion de Ingenieria de Superficies, Departamento de Ciencia de los Materiales, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, 28040 Madrid (Spain); Sanchez, L. [Grupo de Investigacion de Ingenieria de Superficies, Departamento de Ciencia de los Materiales, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, 28040 Madrid (Spain); Bolivar, F.J. [Grupo de Investigacion de Ingenieria de Superficies, Departamento de Ciencia de los Materiales, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, 28040 Madrid (Spain)

    2006-05-10

    The use of chemical vapor deposition by fluidized bed reactors (CVD-FBR) offers some advantages in comparison to other coating techniques such as pack cementation, because it allows coating deposition at lower temperatures than pack cementation and at atmospheric pressure without affecting the mechanical properties of material due to heat treatments of the bulk during coating process. Aluminum and aluminum/silicon coatings have been obtained on two different ferritics steels (P-91 and P-92). The coatings were analyzed using several techniques like SEM/EDX and XRD. The results indicated that both coatings were form by Fe{sub 2}Al{sub 5} intermetallic compound, and in the co-deposition the Si was incorporated to the Fe{sub 2}Al{sub 5} structure in small amounts.

  15. CO{sub 2} laser-induced plasma CVD synthesis of diamond

    Energy Technology Data Exchange (ETDEWEB)

    Konov, V.I.; Prokhorov, A.M.; Uglov, S.A.; Bolshakov, A.P.; Leontiev, I.A. [Rossijskaya Akademiya Nauk, Moscow (Russian Federation). Inst. Obshchej Fiziki; Dausinger, F.; Huegel, H.; Angstenberger, B. [Institute of High Power Beam Technology (IFSW), Stuttgart University, Pfaffenwaldring 43, D-70569 Stuttgart (Germany); Sepold, G.; Metev, S. [Bremen Institute of Applied Beam Technology, D-28800 Bremen 33, Klagenfurter Str. 2 (Germany)

    1998-05-01

    A novel technique for CVD synthesis of materials that does not demand a vacuum chamber and provides high deposition rates has been developed. It is based on CO{sub 2} laser maintenance of a stationary optical discharge in a gas stream, exhausting over a substrate into the air (laser plasmatron). Nano- and polycrystalline-diamond films were deposited on tungsten substrates from atmospheric-pressure Xe(Ar):H{sub 2}:CH{sub 4} gas mixtures at flow rates of 2 l/min. A 2.5-kW CO{sub 2} laser focused beam produced plasma. The deposition area was about 1 cm{sup 2} and growth rates were up to 30-50 {mu}m/h. Peculiarities and advantages of laser plasmatrons are discussed. (orig.) With 4 figs., 4 refs.

  16. Randschicht- und durchgreifendes Härten von 42CrMo4 nach CVD-Beschichtung

    DEFF Research Database (Denmark)

    Pantleon, Karen; Kessler, Olaf; Hoffmann, Franz;

    1999-01-01

    The properties of hard coatings deposited using CVD-processes are usually excellent. However, high deposition temperatures may negativelly influence the properties of the steel substrates, especially in the case of low alloyed steels. Therefore, a subsequent heat treatment is necessary to restore...... the properties of steel substrates ready for operation. Bulk hardening and induction surface hardening as two different post-deposition heat treatments are applied on TiN-coated 42CrMo4 (AISI 4140) substrates. The results show great advantages of induction surface hardening because only low distortion appear...... and the properties of the steel substrates are improved without loosing good coating properties. Thereby, the properties of the steel substrates can be influenced by the parameters of induction heating in a wide range....

  17. Mechanics-driven patterning of CVD graphene for roll-based manufacturing process

    Science.gov (United States)

    Kim, Sang-Min; Jang, Bongkyun; Jo, Kyungmin; Kim, Donghyuk; Lee, Jihye; Kim, Kyung-Shik; Lee, Seung-Mo; Lee, Hak-Joo; Han, Seung Min; Kim, Jae-Hyun

    2017-06-01

    Graphene is considered as a promising material for flexible and transparent electrodes due to its outstanding electrical, optical, and mechanical properties. Efforts to mass-produce graphene electrodes led to the development of roll-to-roll chemical vapor deposition (CVD) graphene growth and transfer, and the only remaining obstacle to the mass-production of CVD graphene electrodes is a cost-effective patterning technique that is compatible with the roll-to-roll manufacturing. Herein, we propose a mechanics-driven technique for patterning graphene synthesized on copper foil (commonly used in roll-to-roll manufacturing). The copper foil is exposed to high temperature for a prolonged period during the CVD growth of graphene, and thus can result in recrystallization and grain growth of the copper foil and thereby reducing to the yield strength. This softening behavior of the copper was carefully controlled to allow simple stamp patterning of the graphene. The strength of the underlying substrate was controlled for the accuracy of the residual patterns. The proposed stamp patterning technique is mask-less and photoresist-free, and can be performed at room temperature without high-energy sources such as lasers or plasma. To demonstrate the capability of this process to produce a continuous electrode, a transparent in-plane supercapacitor was fabricated using the proposed patterning technique.

  18. A CVD Diamond Detector for (n,a) Cross-Section Measurements

    CERN Document Server

    Weiss, Christina; Griesmayer, Erich; Guerrero, Carlos

    A novel detector based on the chemical vapor deposition (CVD) diamond technology has been developed in the framework of this PhD, for the experimental determination of (n,a) cross-sections at the neutron time-of-flight facility n_TOF at CERN. The 59Ni(n,a)56Fe cross-section, which is relevant for astrophysical questions as well as for risk-assessment studies in nuclear technology, has been measured in order to validate the applicability of the detector for such experiments. The thesis is divided in four parts. In the introductory part the motivation for measuring (n,a) cross-sections, the experimental challenges for such measurements and the reasons for choosing the CVD diamond technology for the detector are given. This is followed by the presentation of the n_TOF facility, an introduction to neutron-induced nuclear reactions and a brief summary of the interaction of particles with matter. The CVD diamond technology and the relevant matters related to electronics are given as well in this first part of the t...

  19. Radio Frequency Transistors and Circuits Based on CVD MoS2.

    Science.gov (United States)

    Sanne, Atresh; Ghosh, Rudresh; Rai, Amritesh; Yogeesh, Maruthi Nagavalli; Shin, Seung Heon; Sharma, Ankit; Jarvis, Karalee; Mathew, Leo; Rao, Rajesh; Akinwande, Deji; Banerjee, Sanjay

    2015-08-12

    We report on the gigahertz radio frequency (RF) performance of chemical vapor deposited (CVD) monolayer MoS2 field-effect transistors (FETs). Initial DC characterizations of fabricated MoS2 FETs yielded current densities exceeding 200 μA/μm and maximum transconductance of 38 μS/μm. A contact resistance corrected low-field mobility of 55 cm(2)/(V s) was achieved. Radio frequency FETs were fabricated in the ground-signal-ground (GSG) layout, and standard de-embedding techniques were applied. Operating at the peak transconductance, we obtain short-circuit current-gain intrinsic cutoff frequency, fT, of 6.7 GHz and maximum intrinsic oscillation frequency, fmax, of 5.3 GHz for a device with a gate length of 250 nm. The MoS2 device afforded an extrinsic voltage gain Av of 6 dB at 100 MHz with voltage amplification until 3 GHz. With the as-measured frequency performance of CVD MoS2, we provide the first demonstration of a common-source (CS) amplifier with voltage gain of 14 dB and an active frequency mixer with conversion gain of -15 dB. Our results of gigahertz frequency performance as well as analog circuit operation show that large area CVD MoS2 may be suitable for industrial-scale electronic applications.

  20. Giant enhancement in vertical conductivity of stacked CVD graphene sheets by self-assembled molecular layers

    Science.gov (United States)

    Liu, Yanpeng; Yuan, Li; Yang, Ming; Zheng, Yi; Li, Linjun; Gao, Libo; Nerngchamnong, Nisachol; Nai, Chang Tai; Sangeeth, C. S. Suchand; Feng, Yuan Ping; Nijhuis, Christian A.; Loh, Kian Ping

    2014-11-01

    Layer-by-layer-stacked chemical vapour deposition (CVD) graphene films find applications as transparent and conductive electrodes in solar cells, organic light-emitting diodes and touch panels. Common to lamellar-type systems with anisotropic electron delocalization, the plane-to-plane (vertical) conductivity in such systems is several orders lower than its in-plane conductivity. The poor electronic coupling between the planes is due to the presence of transfer process organic residues and trapped air pocket in wrinkles. Here we show the plane-to-plane tunnelling conductivity of stacked CVD graphene layers can be improved significantly by inserting 1-pyrenebutyric acid N-hydroxysuccinimide ester between the graphene layers. The six orders of magnitude increase in plane-to-plane conductivity is due to hole doping, orbital hybridization, planarization and the exclusion of polymer residues. Our results highlight the importance of interfacial modification for enhancing the performance of LBL-stacked CVD graphene films, which should be applicable to other types of stacked two-dimensional films.

  1. Effect of deposition temperature on the structural and optical properties of CdSe QDs thin films deposited by CBD method

    Energy Technology Data Exchange (ETDEWEB)

    Laatar, F., E-mail: fakher8laatar@gmail.com [Photovoltaic Laboratory, Centre for Research and Technology Energy, Tourist Route Soliman, BP 95, 2050 Hammam-Lif (Tunisia); Harizi, A. [Photovoltaic and Semiconductor Materials Laboratory, Engineering Industrial Department, ENIT, Tunis El Manar University, BP 37, Le Belvédère, 1002 Tunis (Tunisia); Smida, A. [Photovoltaic Laboratory, Centre for Research and Technology Energy, Tourist Route Soliman, BP 95, 2050 Hammam-Lif (Tunisia); Hassen, M. [Photovoltaic Laboratory, Centre for Research and Technology Energy, Tourist Route Soliman, BP 95, 2050 Hammam-Lif (Tunisia); Higher Institute of Applied Science and Technology of Sousse, City Taffala (Ibn Khaldun), 4003 Sousse (Tunisia); Ezzaouia, H. [Photovoltaic Laboratory, Centre for Research and Technology Energy, Tourist Route Soliman, BP 95, 2050 Hammam-Lif (Tunisia)

    2016-06-15

    Highlights: • Synthesis of CdSe QDs with L-Cysteine capping agent for applications in nanodevices. • The films of CdSe QDs present uniform and good dispersive particles at the surface. • Effect of bath temperature on the structural and optical properties of CdSe QDs thin films. • Investigation of the optical constants and dispersion parameters of CdSe QDs thin films. - Abstract: Cadmium selenide quantum dots (CdSe QDs) thin films were deposited onto glass substrates by a chemical bath deposition (CBD) method at different temperatures from an aqueous solution containing L-Cysteine (L-Cys) as capping agent. The evolution of the surface morphology and elemental composition of the CdSe films were studied by AFM, SEM, and EDX analyses. Structural and optical properties of CdSe thin films were investigated by XRD, UV–vis and PL spectroscopy. The dispersion behavior of the refractive index is described using the single oscillator Wemple-DiDomenico (W-D) model, and the physical dispersion parameters are calculated as a function of deposition temperature. The dispersive optical parameters such as average oscillator energy (E{sub o}), dispersion energy (E{sub d}), and static refractive index (n{sub o}) were found to vary with the deposition temperature. Besides, the electrical free carrier susceptibility (χ{sub e}) and the carrier concentration of the effective mass ratio (N/m*) were evaluated according to the Spitzer-Fan model.

  2. An automatic modeling system of the reaction mechanisms for chemical vapor deposition processes using real-coded genetic algorithms.

    Science.gov (United States)

    Takahashi, Takahiro; Nakai, Hiroyuki; Kinpara, Hiroki; Ema, Yoshinori

    2011-09-01

    The identification of appropriate reaction models is very helpful for developing chemical vapor deposition (CVD) processes. In this study, we have developed an automatic system to model reaction mechanisms in the CVD processes by analyzing the experimental results, which are cross-sectional shapes of the deposited films on substrates with micrometer- or nanometer-sized trenches. We designed the inference engine to model the reaction mechanism in the system by the use of real-coded genetic algorithms (RCGAs). We studied the dependence of the system performance on two methods using simple genetic algorithms (SGAs) and the RCGAs; the one involves the conventional GA operators and the other involves the blend crossover operator (BLX-alpha). Although we demonstrated that the systems using both the methods could successfully model the reaction mechanisms, the RCGAs showed the better performance with respect to the accuracy and the calculation cost for identifying the models.

  3. Single step deposition method for nearly stoichiometric CuInSe{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Karthikeyan, Sreejith, E-mail: s.karthikeyan@edu.salford.ac.u [Materials and Physics Research Centre, University of Salford, Salford, M5 4WT (United Kingdom); Hill, Arthur E.; Pilkington, Richard D.; Cowpe, John S. [Materials and Physics Research Centre, University of Salford, Salford, M5 4WT (United Kingdom); Hisek, Joerg [Technische Universitaet Braunschweig, Hannover (Germany); Bagnall, Darren M. [School of Electronics and Computer Science, University of Southampton, SO17 1BJ (United Kingdom)

    2011-03-01

    This paper reports the production of high quality copper indium diselenide thin films using pulsed DC magnetron sputtering from a powder target. As-grown thin films consisted of pin-hole free, densely packed grains. X-ray diffraction showed that films were highly orientated in the (112) and/or (204)/(220) direction with no secondary phases present. The most surprising and exciting outcome of this study was that the as-grown films were of near stoichiometric composition, almost independent of the composition of the starting material. No additional steps or substrate heating were necessary to incorporate selenium and create single phase CuInSe{sub 2}. Electrical properties obtained by hot point probe and four point probe gave values of low resistivity and showed that the films were all p-type. The physical and structural properties of these films were analyzed using X-ray diffraction, scanning electron microscopy and atomic force microscopy. Resistivity measurements were carried out using the four point probe and hot probe methods. The single step deposition process can cut down the cost of the complex multi step processes involved in the traditional vacuum based deposition techniques.

  4. Apparatus and method for selective area deposition of thin films on electrically biased substrates

    Science.gov (United States)

    Zuhr, Raymond A.; Haynes, Tony E.; Golanski, Andrzej

    1994-01-01

    An ion beam deposition process for selective area deposition on a polarized substrate uses a potential applied to the substrate which allows the ionized particles to reach into selected areas for film deposition. Areas of the substrate to be left uncoated are held at a potential that repells the ionized particles.

  5. Utilization of Neutron Bang-time CVD diamond detectors at the Z Accelerator

    Science.gov (United States)

    Chandler, Gordon; Hahn, Kelly; Ruiz, Carlos; Jones, Brent; Gomez, Matthew; Hess, Mark; Harding, Eric; Knapp, Patrick; Bur, James; Torres, Jose; Norris, Edward; Cooper, Gary; Styron, Jedediah; Moy, Ken; McKenna, Ian; Glebov, Vladimir; Fittinghoff, David; May, Mark; Snyder, Lucas

    2016-10-01

    We are utilizing Chemical Vapor Deposited (CVD) Diamond detectors at 2.3 meters on the Z accelerator to infer neutron bang-times from Magnetized Liner Inertial Fusion (MagLIF) sources yielding up to 3e12 DD neutrons and to bound the neutron time history of Deuterium Gas Puff loads producing 5e13 DD neutrons. The current implementation of the diagnostic and initial results will be shown as well as our future plans for the diagnostic. Sandia is sponsored by the U.S. DOE's NNSA under contract DE-AC04-94AL85000.

  6. Thin-film deposition method assisted by mid-infrared-FEL

    CERN Document Server

    Yasumoto, M; Ishizu, A; Tsubouchi, N; Awazu, K; Umesaki, N

    2001-01-01

    We propose the novel application of the mid-infrared (MIR) FEL to the thin-film fabrication process. During the application, a substrate on which a thin film is being fabricated by a conventional method is simultaneously irradiated by the MIR FEL. The MIR FEL induces the fabricated molecules into the excited state of the stretching vibration energy, when the photon energy of the MIR FEL corresponds to one of the molecules. Therefore, the method can assist the thin-film fabrication quasi-independent of the substrate temperature. The method has the advantages of application on a temperature sensitive substrate and selective fabrication due to the tunable wavelength of the MIR FEL. In order to realize the method, we developed two thin film fabrication devices; an MIR FEL assisted RF sputtering device and an MIR FEL assisted laser ablation deposition device. For the method, the intensity of the assisted MIR FEL is an important problem. Thus the cross-section of the MIR FEL intensity profile is shown and the propa...

  7. An Advanced Electrospinning Method of Fabricating Nanofibrous Patterned Architectures with Controlled Deposition and Desired Alignment

    Science.gov (United States)

    Rasel, Sheikh Md

    We introduce a versatile advanced method of electrospinning for fabricating various kinds of nanofibrous patterns along with desired alignment, controlled amount of deposition and locally variable density into the architectures. In this method, we employed multiple electrodes whose potentials have been altered in milliseconds with the help of microprocessor based control system. Therefore, key success of this method was that the electrical field as well as charge carrying fibers could be switched shortly from one electrode's location to another, as a result, electrospun fibers could be deposited on the designated areas with desired alignment. A wide range of nanofibrous patterned architectures were constructed using proper arrangement of multiple electrodes. By controlling the concurrent activation time of two adjacent electrodes, we demonstrated that amount of fibers going into the pattern can be adjusted and desired alignment in electrospun fibers can be obtained. We also revealed that the deposition density of electrospun fibers in different areas of patterned architectures can be varied. We showed that by controlling the deposition time between two adjacent electrodes, a number of functionally graded patterns can be generated with uniaxial alignment. We also demonstrated that this handy method was capable of producing random, aligned, and multidirectional nanofibrous mats by engaging a number of electrodes and switching them in desired patterns. A comprehensive study using finite element method was carried out to understand the effects of electrical field. Simulation results revealed that electrical field strength alters shortly based on electrode control switch patterns. Nanofibrous polyvinyl alcohol (PVA) scaffolds and its composite reinforced with wollastonite and wood flour were fabricated using rotating drum electrospinning technique. Morphological, mechanical, and thermal, properties were characterized on PVA/wollastonite and PVA/wood flour nanocomposites

  8. Atomic-Scale Kinetic Monte Carlo Simulation of {100}-Oriented Diamond Film Growth in C-H and C-H-Cl Systems by Chemical Vapour Deposition

    Institute of Scientific and Technical Information of China (English)

    安希忠; 张禹; 刘国权; 秦湘阁; 王辅忠; 刘胜新

    2002-01-01

    We simulate the { 100}-oriented diamond film growth of chemical vapour deposition (CVD) under different modelsin C-H and C-H-CI systems in an atomic scale by using the revised kinetic Monte Carlo method. The sirnulationresults show that: (1) the CVD diamond flm growth in the C-H system is suitable for high substrate temperature,and the flm surface roughness is very coarse; (2) the CVD diamond film can grow in the C-H-C1 system eitherat high temperature or at low temperature, and the film quality is outstanding; (3) atomic CI takes ala activerole for the growth of diamond film, especially at low temperatures. The concentration of atomic C1 should becontrolled in a proper range.

  9. Carbon Nanotubes Deposited by Hot Wire Plasma CVD and water assisted CVD for Energetic and Environmental Applications

    OpenAIRE

    2014-01-01

    Nanoscience and Nanotechnology have experienced a tremendous growth in few years. Nanotechnologies are the design, characterization, production and application of structures, devices and systems by controlling shape and size at nanometer scale. Carbon exists in several forms, depending on how the carbon atoms are arranged, their properties vary. One of the carbon forms is carbon nanotubes, which are capped at each end by half of a fullerene, and have aroused great interest in the research com...

  10. A New Method for in Situ Measurement of Bt-Maize Pollen Deposition on Host-Plant Leaves

    Directory of Open Access Journals (Sweden)

    Rudolph Vögel

    2011-02-01

    Full Text Available Maize is wind pollinated and produces huge amounts of pollen. In consequence, the Cry toxins expressed in the pollen of Bt maize will be dispersed by wind in the surrounding vegetation leading to exposure of non-target organisms (NTO. NTO like lepidopteran larvae may be affected by the uptake of Bt-pollen deposited on their host plants. Although some information is available to estimate pollen deposition on host plants, recorded data are based on indirect measurements such as shaking or washing off pollen, or removing pollen with adhesive tapes. These methods often lack precision and they do not include the necessary information such as the spatial and temporal variation of pollen deposition on the leaves. Here, we present a new method for recording in situ the amount and the distribution of Bt-maize pollen deposited on host plant leaves. The method is based on the use of a mobile digital microscope (Dino-Lite Pro, including DinoCapture software, which can be used in combination with a notebook in the field. The method was evaluated during experiments in 2008 to 2010. Maize pollen could be correctly identified and pollen deposition as well as the spatial heterogeneity of maize pollen deposition was recorded on maize and different lepidopteran host plants (Centaurea scabiosa, Chenopodium album, Rumex spp., Succina pratensis and Urtica dioica growing adjacent to maize fields.

  11. The growth and characterization of ZnSe nanoneedles by a simple chemical vapor deposition method

    Science.gov (United States)

    Fu, Hongzhi; Li, Huanyong; Jie, Wanqi; Yang, Lan

    2006-04-01

    ZnSe nanoneedles were successfully synthesized with the assistance of NiSe through a simple chemical vapor deposition method for the first time. The ZnSe nanoneedles, with the average bottom diameters of 400 nm and the lengths of more than 50 μm, decrease in diameters from bottom to tip. The diameter of the nanoneedle can be controlled by the size of NiSe source. The products were also characterized by XRD, HRTEM, EDS and PL spectrum. The ZnSe nanoneedles are of a single crystal in nature with high crystalline quality, and is the preferential growth direction. A strong emission band around 438.9 nm is observed at room temperature, being attributed to the excitonic emission. A combined mechanism of the redox effect and the VLS mechanism is proposed to understand the growth of ZnSe nanoneedles.

  12. Chemical solution deposition method of fabricating highly aligned MgO templates

    Science.gov (United States)

    Paranthaman, Mariappan Parans [Knoxville, TN; Sathyamurthy, Srivatsan [Knoxville, TN; Aytug, Tolga [Knoxville, TN; Arendt, Paul N [Los Alamos, NM; Stan, Liliana [Los Alamos, NM; Foltyn, Stephen R [Los Alamos, NM

    2012-01-03

    A superconducting article includes a substrate having an untextured metal surface; an untextured barrier layer of La.sub.2Zr.sub.2O.sub.7 or Gd.sub.2Zr.sub.2O.sub.7 supported by and in contact with the surface of the substrate; a biaxially textured buffer layer supported by the untextured barrier layer; and a biaxially textured superconducting layer supported by the biaxially textured buffer layer. Moreover, a method of forming a buffer layer on a metal substrate includes the steps of: providing a substrate having an untextured metal surface; coating the surface of the substrate with a barrier layer precursor; converting the precursor to an untextured barrier layer; and depositing a biaxially textured buffer layer above and supported by the untextured barrier layer.

  13. Microstructure and Corrosion Resistance of Aluminium and Copper Composite Coatings Deposited by LPCS Method

    Directory of Open Access Journals (Sweden)

    Winnicki M.

    2016-12-01

    Full Text Available The paper presents the study of microstructure and corrosion resistance of composite coatings (Al+Al2O3 and Cu+Al2O3 deposited by Low Pressure Cold Spraying method (LPCS. The atmospheric corrosion resistance was examined by subjecting the samples to cyclic salt spray and Kesternich test chambers, with NaCl and SO2 atmospheres, respectively. The selected tests allowed reflecting the actual working conditions of the coatings. The analysis showed very satisfactory results for copper coatings. After eighteen cycles, with a total time of 432 hours, the samples show little signs of corrosion. Due to their greater susceptibility to chloride ions, aluminium coatings have significant corrosion losses.

  14. Ultrafast erbium-doped fiber laser mode-locked by a CVD-grown molybdenum disulfide (MoS2) saturable absorber.

    Science.gov (United States)

    Xia, Handing; Li, Heping; Lan, Changyong; Li, Chun; Zhang, Xiaoxia; Zhang, Shangjian; Liu, Yong

    2014-07-14

    We demonstrate an erbium-doped fiber laser passively mode-locked by a multilayer molybdenum disulfide (MoS(2)) saturable absorber (SA). The multilayer MoS(2) is prepared by the chemical vapor deposition (CVD) method and transferred onto the end-face of a fiber connector. Taking advantage of the excellent saturable absorption of the fabricated MoS(2)-based SA, stable mode locking is obtained at a pump threshold of 31 mW. Resultant output soliton pulses have central wavelength, spectral width, pulse duration, and repetition rate of 1568.9 nm, 2.6 nm, 1.28 ps, and 8.288 MHz, respectively. The experimental results show that multilayer MoS(2) is a promising material for ultrafast laser systems.

  15. Study of relationship between pulse pressure and mortality from all the causes, CVD and CVA

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Objective: To determine the relationship between pulse pressure and mortality from all the causes: CVD and CVA. Methods: The cohort consisted of the beneficiaries from Korea Medical Insurance Corporation (KMIC) aged 40 and older who had taken health examination and completed the questionnaire inquiring of health habits and past medical history in 1992 or 1993. The number of cohort members was 698,796, and they were followed up from 1st January, 1994 until 31st December, 2000. The primary sources of the data used in this study were the death benefit record and health examination file of KMIC. In the case that the information about the cause of death was unknown in the death benefit record, it was checked from the death registry of National statistical Office and the inpatient data of KMIC. There were 37439 deaths during the follow-up period. Results: A linear relationship between pulse pressure and mortality from all the causes, cardiovascular disease and cerebrovascular disease, was determined in both genders, the whole population and age groups, in the hypertensive and normotensive ( P< 0. 01). Pulse pressure and mortality from all the causes, CVD and CVA increased ( P <0.01). Pulse pressure was significantly associated with a relatively high risk of mortality from all the causes, CVD and CVA in the whole population, both genders, all age groups, the hypertensive and normotensive after adjusted to age, gender, body mass index, blood sugar, serum total cholesterol, AST, ALT, urine protein, urine glucose, alcohol drinking and cigarette smoking ( P< 0.01). Conclusion: Pulse pressure shows linear relationship with the mortality from all the causes,CVD and CVA. Pulse pressure appears to be a single measure of blood pressure in predicting mortality from all the causes,CVD and CVA, even in the hypertensive and normotensive.

  16. Effects of FeO{sub x}, CoO{sub x}, and NiO catalysts and calcination temperatures on the synthesis of single-walled carbon nanotubes through chemical vapor deposition of methane

    Energy Technology Data Exchange (ETDEWEB)

    Tan, S.-M. [School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, Seri Ampangan, 14300 Nibong Tebal, S.P.S. Pulau Pinang (Malaysia); Chai, S.-P. [School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, Seri Ampangan, 14300 Nibong Tebal, S.P.S. Pulau Pinang (Malaysia); School of Engineering, Monash University, Jalan Lagoon Selatan, 46150 Bandar Sunway, Selangor (Malaysia); Liu, W.-W. [School of Materials Science and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, Seri Ampangan, 14300 Nibong Tebal, S.P.S. Pulau Pinang (Malaysia); Mohamed, Abdul Rahman [School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, Seri Ampangan, 14300 Nibong Tebal, S.P.S. Pulau Pinang (Malaysia)], E-mail: chrahman@eng.usm.my

    2009-05-27

    The oxides of cobalt, iron, and nickel catalysts were tested in chemical vapor deposition (CVD) of methane in synthesizing single-walled carbon nanotubes (SWNTs). All catalysts used in this study were prepared using impregnation method and calcined at temperatures ranging from 300 to 850 deg. C. The catalyst samples after CVD of methane were characterized using transmission electron microscopy (TEM). The TEM study elucidates that iron oxide serves as an effective catalyst for growing SWNTs. The presence of SWNTs on the catalyst was confirmed in the Raman study.

  17. Thickness Measurement Methods for Physical Vapor Deposited Aluminum Coatings in Packaging Applications: A Review

    Directory of Open Access Journals (Sweden)

    Martina Lindner

    2017-01-01

    Full Text Available The production of barrier packaging materials, e.g., for food, by physical vapor deposition (PVD of inorganic coatings such as aluminum on polymer substrates is an established and well understood functionalization technique today. In order to achieve a sufficient barrier against gases, a coating thickness of approximately 40 nm aluminum is necessary. This review provides a holistic overview of relevant methods commonly used in the packaging industry as well as in packaging research for determining the aluminum coating thickness. The theoretical background, explanation of methods, analysis and effects on measured values, limitations, and resolutions are provided. In industrial applications, quartz micro balances (QCM and optical density (OD are commonly used for monitoring thickness homogeneity. Additionally, AFM (atomic force microscopy, electrical conductivity, eddy current measurement, interference, and mass spectrometry (ICP-MS are presented as more packaging research related methods. This work aims to be used as a guiding handbook regarding the thickness measurement of aluminum coatings for packaging technologists working in the field of metallization.

  18. Boring of full scale deposition holes using a novel dry blind boring method

    Energy Technology Data Exchange (ETDEWEB)

    Autio, J.; Kirkkomaeki, T. [Saanio and Riekkola Oy, Helsinki (Finland)

    1996-10-01

    Three holes the size of deposition holes (depth 7.5 m and diameter 1.5 m) were bored in the Research Tunnel at Olkiluoto, Finland. A novel full-face boring technique was used based on rotary crushing of rock and removal of crushed rock by vacuum flushing through the drill string. The purpose of the work was to demonstrate the feasibility of the technique. During the boring test procedures were carried out in order to determine the effect of changes in operating parameters on the performance of the boring machine and the quality of the hole. The boring method was found to be technically feasible and efficient. Evaluation of the quality of the hole included studies of the geometry of the hole, measurements of the surface roughness using a laser profilometer and study of excavation disturbances in the zone adjacent to the surface of the holes using two novel methods, He-gas diffusion and the {sup 14}C-polymethylmethacrylate methods. 43 refs.

  19. Electro-deposition as a repair method for embedded metal grids

    Energy Technology Data Exchange (ETDEWEB)

    Oostra, A. Jolt [Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG, Groningen (Netherlands); Reddy, Anil; Smits, Edsger C.P.; Abbel, Robert; Groen, Wilhelm A. [Holst Centre/TNO, High Tech Campus 31, 5605 KN Eindhoven (Netherlands); Blom, Paul W.M. [Max Planck Institute für Polymerforschung, Ackermannweg 10, 55128 Mainz (Germany); Michels, Jasper J., E-mail: michels@mpip-mainz.mpg.de [Holst Centre/TNO, High Tech Campus 31, 5605 KN Eindhoven (Netherlands); Max Planck Institute für Polymerforschung, Ackermannweg 10, 55128 Mainz (Germany)

    2016-03-31

    A method is presented to self-repair cracks in embedded silver grid structures used in large area organic electronics. The repair procedure is based on electro-deposition, incited by the application of a moderate DC voltage across the crack. During this process the organic anode that is in direct electrical contact with the silver grid, functions as an appropriate medium for ion migration. Restoration of conductivity is achieved by the formation of dendritic metal structures that connect the cathodic to the anodic side of the crack. The metal dendrites decrease the gap resistance by one order of magnitude. Subsequently, another three orders of magnitude are gained upon sintering the dendrites using a high voltage pulse, yielding restored conductance levels nearly within one order of magnitude difference from native track conductance. - Highlights: • An innovative method to repair cracks in embedded silver electrodes is presented. • The method targets application in flexible hybrid- and organic electronics. • The mechanism relies on dendritic growth of metallic structures. • Sintering yields restored conductivity levels approaching the original value.

  20. CVD synthesis of polycrystalline magnetite thin films: structural, magnetic and magnetotransport properties

    Energy Technology Data Exchange (ETDEWEB)

    Mantovan, R; Lamperti, A; Georgieva, M; Tallarida, G; Fanciulli, M, E-mail: roberto.mantovan@mdm.infm.i [Laboratorio Nazionale MDM CNR-INFM, Via C. Olivetti 2, 20041 Agrate Brianza (Italy)

    2010-02-17

    Magnetite (Fe{sub 3}O{sub 4}) is predicted to be half metallic at room temperature (RT) and it shows the highest Curie temperature among oxides. The use of Fe{sub 3}O{sub 4} thin films is therefore promising for spintronic devices such as magnetic tunnel junctions (MTJs) and magnetoresistive sensors. The structural, magnetic and magnetotransport properties of magnetite are reported to be strongly dependent on the growth conditions. We have developed a very simple deposition chamber for growing thin magnetite films via a chemical vapour deposition (CVD) process based on the Fe{sub 3}(CO){sub 12} carbonyl precursor. The structural, morphological, and magnetic properties of the as deposited Fe{sub 3}O{sub 4} films have been investigated by means of time of flight secondary ion mass spectrometry, grazing incidence x-ray diffraction, x-ray reflectivity, atomic force microscopy, conversion electron Moessbauer spectroscopy and superconducting quantum interference device magnetometry. Magnetotransport measurements show magnetoresistance up to -2.4% at RT at the maximum applied field of 1.1 T. Resistivity measurements in the 100-300 K temperature range reveal that the magnetotransport properties of the Fe{sub 3}O{sub 4} films are governed by inter-granular tunnelling of the spin-polarized electrons. The spin polarization is estimated to be around -16%. A possible route for increasing the spin-polarized performances of our magnetite films is proposed. We have also deposited Fe{sub 3}O{sub 4}/MgO/Co stacks by using a combined CVD and atomic layer-deposition process. The trilayer's hysteresis curve evidences the presence of two distinct switching fields making it promising for magnetite-based MTJ applications.

  1. CVD synthesis of polycrystalline magnetite thin films: structural, magnetic and magnetotransport properties

    Science.gov (United States)

    Mantovan, R.; Lamperti, A.; Georgieva, M.; Tallarida, G.; Fanciulli, M.

    2010-02-01

    Magnetite (Fe3O4) is predicted to be half metallic at room temperature (RT) and it shows the highest Curie temperature among oxides. The use of Fe3O4 thin films is therefore promising for spintronic devices such as magnetic tunnel junctions (MTJs) and magnetoresistive sensors. The structural, magnetic and magnetotransport properties of magnetite are reported to be strongly dependent on the growth conditions. We have developed a very simple deposition chamber for growing thin magnetite films via a chemical vapour deposition (CVD) process based on the Fe3(CO)12 carbonyl precursor. The structural, morphological, and magnetic properties of the as deposited Fe3O4 films have been investigated by means of time of flight secondary ion mass spectrometry, grazing incidence x-ray diffraction, x-ray reflectivity, atomic force microscopy, conversion electron Mössbauer spectroscopy and superconducting quantum interference device magnetometry. Magnetotransport measurements show magnetoresistance up to -2.4% at RT at the maximum applied field of 1.1 T. Resistivity measurements in the 100-300 K temperature range reveal that the magnetotransport properties of the Fe3O4 films are governed by inter-granular tunnelling of the spin-polarized electrons. The spin polarization is estimated to be around -16%. A possible route for increasing the spin-polarized performances of our magnetite films is proposed. We have also deposited Fe3O4/MgO/Co stacks by using a combined CVD and atomic layer-deposition process. The trilayer's hysteresis curve evidences the presence of two distinct switching fields making it promising for magnetite-based MTJ applications.

  2. Effect of plating time on growth of nanocrystalline Ni–P from sulphate/glycine bath by electroless deposition method

    Indian Academy of Sciences (India)

    N Latha; V Raj; M Selvam

    2013-08-01

    Nanocrystalline nickel phosphorus (NC-Ni–P) deposits from sulphate/glycine bath using a simple electroless deposition process is demonstrated. In the present investigation, nanoporous alumina films are formed on the aluminium surface by anodization process followed by deposition of nickel onto the pores by electroless plating method. Anodic aluminium oxide surface was first sensitized and activated by using palladium chloride solution before immersing into the electroless nickel bath. Electroless nickel plating was carried out from the optimized bath by changing the deposition time from 20 to 1800 s at a constant temperature of 80 °C and a pH of 4.0. Surface morphology, elemental composition, structure and reflectance of the deposits have been analysed by using scanning electron microscopy, atomic force microscopy, energy dispersive X-ray analysis, X-ray diffractometry and UV-visible spectroscopic studies, respectively. Electroless nickel deposits formed at an early stage produces dense uniform nanocrystals containing higher percentage of atomic phosphorus with cubic Ni (111) structure. As the deposition time increased, nanocrystalline sharp peak became amorphous and dimension of the crystal size varied from 54 to 72 nm.

  3. Direct-Liquid-Evaporation Chemical Vapor Deposition of Nanocrystalline Cobalt Metal for Nanoscale Copper Interconnect Encapsulation.

    Science.gov (United States)

    Feng, Jun; Gong, Xian; Lou, Xiabing; Gordon, Roy G

    2017-03-29

    In advanced microelectronics, precise design of liner and capping layers become critical, especially when it comes to the fabrication of Cu interconnects with dimensions lower than its mean free path. Herein, we demonstrate that direct-liquid-evaporation chemical vapor deposition (DLE-CVD) of Co is a promising method to make liner and capping layers for nanoscale Cu interconnects. DLE-CVD makes pure, smooth, nanocrystalline, and highly conformal Co films with highly controllable growth characteristics. This process allows full Co encapsulation of nanoscale Cu interconnects, thus stabilizing Cu against diffusion and electromigration. Electrical measurements and high-resolution elemental imaging studies show that the DLE-CVD Co encapsulation layer can improve the reliability and thermal stability of Cu interconnects. Also, with the high conductivity of Co, the DLE-CVD Co encapsulation layer have the potential to further decrease the power consumption of nanoscale Cu interconnects, paving the way for Cu interconnects with higher efficiency in future high-end microelectronics.

  4. Investigations of high mobility single crystal chemical vapor deposition diamond for radiotherapy photon beam monitoring

    Science.gov (United States)

    Tromson, D.; Descamps, C.; Tranchant, N.; Bergonzo, P.; Nesladek, M.; Isambert, A.

    2008-03-01

    The intrinsic properties of diamond make this material theoretically very suitable for applications in medical physics. Until now ionization chambers have been fabricated from natural stones and are commercialized by PTW, but their fairly high costs and long delivery times have often limited their use in hospital. The properties of commercialized intrinsic polycrystalline diamond were investigated in the past by many groups. The results were not completely satisfactory due to the nature of the polycrystalline material itself. In contrast, the recent progresses in the growth of high mobility single crystal synthetic diamonds prepared by chemical vapor deposition (CVD) technique offer new alternatives. In the framework of the MAESTRO project (Methods and Advanced Treatments and Simulations for Radio Oncology), the CEA-LIST is studying the potentialities of synthetic diamond for new techniques of irradiation such as intensity modulated radiation therapy. In this paper, we present the growth and characteristics of single crystal diamond prepared at CEA-LIST in the framework of the NoRHDia project (Novel Radiation Hard CVD Diamond Detector for Hadrons Physics), as well as the investigations of high mobility single crystal CVD diamond for radiotherapy photon beam monitoring: dosimetric analysis performed with the single crystal diamond detector in terms of stability and repeatability of the response signal, signal to noise ratio, response speed, linearity of the signal versus the absorbed dose, and dose rate. The measurements performed with photon beams using radiotherapy facilities demonstrate that single crystal CVD diamond is a good alternative for air ionization chambers for beam quality control.

  5. THE EFFECT OF DEPOSITION PARAMETERS ON THE CHEMICAL COMPOSITION AND CORROSION RESISTANCE OF TICXNY COATINGS PRODUCED ON HIGH-SPEED STEEL SUBSTRATES

    Directory of Open Access Journals (Sweden)

    Senna L.F.

    2001-01-01

    Full Text Available TiCxNy coatings deposited on high-speed steel substrates have been used to enhance the tribological properties of cutting tools (hardness, wear resistance, etc. as well as their corrosion resistance in an aggressive environment. These layers are usually produced by plasma deposition techniques (PVD or CVD, and different coating properties can be obtained with each method. In this work, TiCxNy films were deposited on AISI M2 high-speed steel substrates by the reactive magnetron sputtering technique. A series of samples with a variety of reactive gas mixtures (nitrogen and methane, substrate biases, and deposition temperatures was produced. As a result, coatings with different chemical compositions were deposited for each group of deposition parameters. Gas mixture composition and substrate bias directly affected the chemical composition of the coating, while deposition temperature influenced the chemical composition of TiCxNy layers to a very low extent.

  6. Advanced methods for processing ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Carter, W.B. [Georgia Institute of Technology, Atlanta, GA (United States)

    1997-04-01

    Combustion chemical vapor deposition (combustion CVD) is being developed for the deposition of high temperature oxide coatings. The process is being evaluated as an alternative to more capital intensive conventional coating processes. The thrusts during this reporting period were the development of the combustion CVD process for depositing lanthanum monazite, the determination of the influence of aerosol size on coating morphology, the incorporation of combustion CVD coatings into thermal barrier coatings (TBCs) and related oxidation research, and continued work on the deposition of zirconia-yttria coatings.

  7. Simulation of Powder Layer Deposition in Additive Manufacturing Processes Using the Discrete Element Method

    Energy Technology Data Exchange (ETDEWEB)

    Herbold, E. B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Walton, O. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Homel, M. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-10-26

    This document serves as a final report to a small effort where several improvements were added to a LLNL code GEODYN-­L to develop Discrete Element Method (DEM) algorithms coupled to Lagrangian Finite Element (FE) solvers to investigate powder-­bed formation problems for additive manufacturing. The results from these simulations will be assessed for inclusion as the initial conditions for Direct Metal Laser Sintering (DMLS) simulations performed with ALE3D. The algorithms were written and performed on parallel computing platforms at LLNL. The total funding level was 3-­4 weeks of an FTE split amongst two staff scientists and one post-­doc. The DEM simulations emulated, as much as was feasible, the physical process of depositing a new layer of powder over a bed of existing powder. The DEM simulations utilized truncated size distributions spanning realistic size ranges with a size distribution profile consistent with realistic sample set. A minimum simulation sample size on the order of 40-­particles square by 10-­particles deep was utilized in these scoping studies in order to evaluate the potential effects of size segregation variation with distance displaced in front of a screed blade. A reasonable method for evaluating the problem was developed and validated. Several simulations were performed to show the viability of the approach. Future investigations will focus on running various simulations investigating powder particle sizing and screen geometries.

  8. Hysteresis dependence on CH3NH3PbI3 deposition method in perovskite solar cells

    Science.gov (United States)

    Fernandes, Silvia Leticia; Bregadiolli, Bruna Andressa; Véron, Anna Christina; Nüesch, Frank A.; Zaghete, Maria Aparecida; Graeff, Carlos Frederico de Oliveira

    2016-09-01

    CH3NH3PbI3 perovskite solar cells are one of the most exciting technologies in the renewable energy field, resulting in over 20% power conversion efficiency. Deep understanding of the working principle is now required to turn the high efficiency solar cells into a reliable technology. In this work we have explored the role of deposition method on the crystallinity of perovskite films and its influence on the hysteresis behavior of the current-voltage characteristics. In addition Nb2O5 was used as hole blocking layer and its influence is also discussed. We have found that hysteresis is strongly dependent on both; perovskite deposition method and Nb2O5 thickness. The ideal condition where the hysteresis is suppressed or minimized was achieved by using the sequential deposition method for the perovskite semiconductor and a hole blocking layer of 50 nm.

  9. Acetylene-sourced CVD-synthesised catalytically active graphene for electrochemical biosensing.

    Science.gov (United States)

    Osikoya, Adeniyi Olugbenga; Parlak, Onur; Murugan, N Arul; Dikio, Ezekiel Dixon; Moloto, Harry; Uzun, Lokman; Turner, Anthony Pf; Tiwari, Ashutosh

    2017-03-15

    In this study, we have demonstrated the use of chemical vapour deposition (CVD) grown-graphene to develop a highly-ordered graphene-enzyme electrode for electrochemical biosensing. The graphene sheets were deposited on 1.00mm thick copper sheet at 850°C using acetylene (C2H2) as carbon source in an argon (Ar) and nitrogen (N2) atmosphere. An anionic surfactant was used to increase wettability and hydrophilicity of graphene; thereby facilitating the assembly of biomolecules on the electrode surface. Meanwhile, the theoretical calculations confirmed the successful modification of hydrophobic nature of graphene through the anionic surface assembly, which allowed high-ordered immobilisation of glucose oxidase (GOx) on the graphene. The electrochemical sensing activities of the graphene-electrode was explored as a model for bioelectrocatalysis. The bioelectrode exhibited a linear response to glucose concentration ranging from 0.2 to 9.8mM, with sensitivity of 0.087µA/µM/cm(2) and a detection limit of 0.12µM (S/N=3). This work sets the stage for the use of acetylene-sourced CVD-grown graphene as a fundamental building block in the fabrication of electrochemical biosensors and other bioelectronic devices.

  10. New exploration methods for platinum and rhodium deposits poor in base-metal sulphides

    DEFF Research Database (Denmark)

    Ohnenstetter, M.; Johan, Z.; Cocherie, A.

    1999-01-01

    of the deposits occur in Albania, in the Tropoja and Bulqiza massifs, and are part of an ophiolitic belt created in an oceanic environment during the Upper Jurassic. The other two deposits occur in Madagascar, in the Andohankiranomena and Lavotrafo ultramafic massifs, and are within a Pan-African rifted zone.A Pt...

  11. Chemical Vapour Deposition of Large Area Graphene

    DEFF Research Database (Denmark)

    Larsen, Martin Benjamin Barbour Spanget

    be eliminated. Further opportunities arise when exchanging the copper foil for copper thin film on a wafer e.g. better integration with current cleanroom processing of devices and better control over the copper crystallinity. Typical strategies for controlling the temperature during CVD fabrication of graphene...... of thermocouples leads to large variations in the grown graphene. This was solved by controlling the temperature through applying a set power to the heat source, resulting in a more stable temperature from process to process. Micro Raman spectroscopy is used to characterize the structural quality of the grown......Chemical Vapor Deposition (CVD) is a viable technique for fabrication of large areas of graphene. CVD fabrication is the most prominent and common way of fabricating graphene in industry. In this thesis I have attempted to optimize a growth recipe and catalyst layer for CVD fabrication of uniform...

  12. Effect of substrate roughness on growth of diamond by hot filament CVD

    Indian Academy of Sciences (India)

    Awadesh K Mallik; S R Binu; L N Satapathy; Chandrabhas Narayana; Md Motin Seikh; S A Shivashankar; S K Biswas

    2010-06-01

    Polycrystalline diamond coatings are grown on Si (100) substrate by hot filament CVD technique. We investigate here the effect of substrate roughening on the substrate temperature and methane concentration required to maintain high quality, high growth rate and faceted morphology of the diamond coatings. It has been shown that as we increase the substrate roughness from 0.05 m to 0.91 m (centre line average or CLA) there is enhancement in deposited film quality (Raman peak intensity ratio of 3 to non-3 content increases from 1.65 to 7.13) and the substrate temperature can be brought down to 640°C without any additional substrate heating. The coatings grown at adverse conditions for 3 deposition has cauliflower morphology with nanocrystalline grains and coatings grown under favourable 3 condition gives clear faceted grains.

  13. Dropwise Condensation of Low Surface Tension Fluids on iCVD Grafted Polymer Films

    Science.gov (United States)

    Khalil, Karim; Gleason, Karen; Varanasi, Kripa

    2016-11-01

    A large majority of the work devoted to surface engineering for promoting dropwise condensation heat transfer has focused on steam. Much less attention has been dedicated to the condensation of low surface tension fluids such as hydrocarbons, cryogens, and fluorinated refrigerants, which are used in several industrial applications, including LNG storage and organic Rankine cycles used for heat recovery from low temperature sources such as biomass combustion, industrial waste, or geothermal heat sources. Most hydrophobic modifiers used previously to promote dropwise condensation are silane-based monolayers that have been shown to rapidly degrade under industrial conditions. Here we investigate condensation behavior of a variety of low surface tension liquids on durable covalently-grafted polymer films deposited using initiated chemical vapor deposition (iCVD) on metals such as titanium. We observe a four to seven-fold improvement in the vapor-side heat transfer coefficient by promoting dropwise condensation of low surface tension fluids on these stable films.

  14. Improved electroless plating method through ultrasonic spray atomization for depositing silver nanoparticles on multi-walled carbon nanotubes

    Science.gov (United States)

    Zhao, Qi; Xie, Ming; Liu, Yichun; Yi, Jianhong

    2017-07-01

    A novel method was developed to deposit nanosized silver particles on multi-walled carbon nanotubes (MWCNTs). The electroless plating of silver on MWCNTs accomplished in small solution drops generated by ultrasonic spray atomization, which inhibited excessive growth of silver particles and led to much more uniform nanometer grain-sized coatings. The results showed that pretreatment was essential for silver particles to deposit on the MWCNTs, and the electrolyte concentration and reaction temperature were important parameters which had a great influence on the morphology and structure of the silver coatings. Possible mechanisms of this method are also discussed in the paper.

  15. Fish consumption and its motives in households with versus without self-reported medical history of CVD: A consumer survey from five European countries

    Directory of Open Access Journals (Sweden)

    Brunsø Karen

    2008-09-01

    Full Text Available Abstract Background The purpose of this study was to explore the cross-cultural differences in the frequency of fish intake and in motivations for fish consumption between people from households with (CVD+ or without (CVD- medical history of cardiovascular disease, using data obtained in five European countries. Methods A cross-sectional consumer survey was carried out in November-December 2004 with representative household samples from Belgium, the Netherlands, Denmark, Poland and Spain. The sample consisted of 4,786 respondents, aged 18–84 and who were responsible for food purchasing and cooking in the household. Results Individuals from households in the CVD+ group consumed fish more frequently in Belgium and in Denmark as compared to those in the CVD- group. The consumption of fatty fish, which is the main sources of omega-3 PUFA associated with prevention of cardiovascular diseases, was on the same level for the two CVD groups in the majority of the countries, except in Belgium where CVD+ subjects reported to eat fatty fish significantly more frequently than CVD- subjects. All respondents perceived fish as a very healthy and nutritious food product. Only Danish consumers reported a higher subjective and objective knowledge related to nutrition issues about fish. In the other countries, objective knowledge about fish was on a low level, similar for CVD+ as for CVD- subjects, despite a higher claimed use of medical information sources about fish among CVD+ subjects. Conclusion Although a number of differences between CVD- and CVD+ subjects with respect to their frequency of fish intake are uncovered, the findings suggest that fish consumption traditions and habits – rather than a medical history of CVD – account for large differences between the countries, particularly in fatty fish consumption. This study exemplifies the need for nutrition education and more effective communication about fish, not only to the people facing chronic

  16. Transport mechanisms through PE-CVD coatings: influence of temperature, coating properties and defects on permeation of water vapour

    Science.gov (United States)

    Kirchheim, Dennis; Jaritz, Montgomery; Mitschker, Felix; Gebhard, Maximilian; Brochhagen, Markus; Hopmann, Christian; Böke, Marc; Devi, Anjana; Awakowicz, Peter; Dahlmann, Rainer

    2017-03-01

    Gas transport mechanisms through plastics are usually described by the temperature-dependent Arrhenius-model and compositions of several plastic layers are represented by the CLT. When it comes to thin films such as plasma-enhanced chemical vapour deposition (PE-CVD) or plasma-enhanced atomic layer deposition (PE-ALD) coatings on substrates of polymeric material, a universal model is lacking. While existing models describe diffusion through defects, these models presume that permeation does not occur by other means of transport mechanisms. This paper correlates the existing transport models with data from water vapour transmission experiments.

  17. Low temperature growth of diamond films on optical fibers using Linear Antenna CVD system

    Science.gov (United States)

    Ficek, M.; Drijkoningen, S.; Karczewski, J.; Bogdanowicz, R.; Haenen, K.

    2016-01-01

    It is not trivial to achieve a good quality diamond-coated fibre interface due to a large difference in the properties and composition of the diamond films (or use coating even) and the optical fibre material, i.e. fused silica. One of the biggest problems is the high temperature during the deposition which influences the optical fibre or optical fibre sensor structure (e.g. long-period gratings (LPG)). The greatest advantage of a linear antenna microwave plasma enhanced chemical vapor deposition system (LA MW CVD) is the fact that it allows to grow the diamond layers at low temperature (below 300°C) [1]. High quality nanocrystalline diamond (NCD) thin films with thicknesses ranging from 70 nm to 150 nm, were deposited on silicon, glass and optical fibre substrates [2]. Substrates pretreatment by dip-coating and spin coating process with a dispersion consisting of detonation nanodiamond (DND) in dimethyl sulfoxide (DMSO) with polyvinyl alcohol (PVA) has been applied. During the deposition process the continuous mode of operation of the LA MW CVD system was used, which produces a continuous wave at a maximum power of 1.9 kW (in each antenna). Diamond films on optical fibres were obtained at temperatures below 350°C, providing a clear improvement of results compared to our earlier work [3]. The samples were characterized by scanning electron microscopy (SEM) imaging to investigate the morphology of the nanocrystalline diamond films. The film growth rate, film thickness, and optical properties in the VIS-NIR range, i.e. refractive index and extinction coefficient will be discussed based on measurements on reference quartz plates by using spectroscopic ellipsometry (SE).

  18. Experimental studies of N~+ implantation into CVD diamond thin films

    Institute of Scientific and Technical Information of China (English)

    辛火平; 林成鲁; 王建新; 邹世昌; 石晓红; 林梓鑫; 周祖尧; 刘祖刚

    1997-01-01

    The effects of N+ implantation under various conditions on CVD diamond films were analyzed with Raman spectroscopy, four-point probe method, X-ray diffraction (XRD), Rutherford backseattering spectroscopy (RBS), ultraviolet photoluminescence spectroscopy (UV-PL), Fourier transformation infrared absorption spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The results show that the N+ implantation doping without any graphitization has been successfully realized when 100 keV N+ ions at a dosage of 2 × 1016 cm-2 were implanted into diamond films at 550℃ . UV-PL spectra indicate that the implanted N+ ions formed an electrically inactive deep-level impurity in diamond films. So the sheet resistance of the sample after N+ implantation changed little. Carbon nitride containing C≡N covalent bond has been successfully synthesized by 100 keV, 1.2×1018 N/cm2 N+ implantation into diamond films. Most of the implanted N+ ions formed C≡N covalent bonds with C atoms. The others were free state nitroge

  19. Improving electrochemical performance of tin-based anodes formed via oblique angle deposition method

    Indian Academy of Sciences (India)

    B Deniz Polat; Ozgul Keles

    2014-12-01

    An oblique angle electron beam co-deposition technique was used to fabricate nanostructured Sn-based thin films: Sn, Cu–Sn and Cu–Sn–C. The morphological and structural properties of the films were observed via scanning electron microscopy (SEM) and thin film X-ray diffraction (XRD) methods. The electrochemical (CV and EIS) and the galvanostatic test results demonstrated that the addition of Cu with or without C affected the electrochemical performance of the thin film positively since Cu and C improved both the mechanical and the electrical properties of the nanostructured Sn thin film electrode. The high cycleability and capacity retention were achieved when the nanostructured Cu–Sn–C thin film was used as an anode material since C increased the mechanical tolerance of the thin film to the volume expansion due to its grain refiner effect. Cu not only improved the electrical conductivity and the adhesion of the film to substrate but also the mechanical tolerance of the film with its ductile property.

  20. Geophysical modeling in gold deposit through DC Resistivity and Induced Polarization methods

    Directory of Open Access Journals (Sweden)

    César Augusto Moreira

    Full Text Available Abstract Ore mining fundamentally depends on the definition of its tenor and volume, something extremely complex in disseminated mineralization, as in the case of certain types of deposits of gold and sulfites. This article proposes the use of electrical tomography for definition of a geophysical signature in terms of electrical resistivity and chargeability, in an outcrop of mineralized quartz lode at the end of an inactive gold mine. One of the targets was to analyze the continuity of the mineralized body, the occurrence of new outcrops and the applicability of the method as an auxiliary tool in mineral extraction. Three parallel lines of electrical tomography in a dipole-dipole arrangement, being orthogonal to the orientation of the gold lode, were installed in an area outside the mine. The results allowed the geophysical characterization of the mineralized zone by high resistivity (above 1000Ω.m and high chargeability (above 30mV/V. The results of the 2D inversion models were interpolated in 3D visualization models, which allowed definition of the contour surfaces for the physical parameters measured, and the morphological pattern modeling of the mineralization. The data reveal the existence of a new lode in subsurface, localized 30m to the south of the lode outcrop. The versatility of the acquisition and data processing indicate the application potential of electrical tomography as a criterion for sampling and tenor definition in ore extraction activities, since it is objective and low cost.