WorldWideScience

Sample records for beam-physical vapor deposition

  1. Metallographic techniques for evaluation of Thermal Barrier Coatings produced by Electron Beam Physical Vapor Deposition

    International Nuclear Information System (INIS)

    Kelly, Matthew; Singh, Jogender; Todd, Judith; Copley, Steven; Wolfe, Douglas

    2008-01-01

    Thermal Barrier Coatings (TBC) produced by Electron Beam Physical Vapor Deposition (EB-PVD) are primarily applied to critical hot section turbine components. EB-PVD TBC for turbine applications exhibit a complicated structure of porous ceramic columns separated by voids that offers mechanical compliance. Currently there are no standard evaluation methods for evaluating EB-PVD TBC structure quantitatively. This paper proposes a metallographic method for preparing samples and evaluating techniques to quantitatively measure structure. TBC samples were produced and evaluated with the proposed metallographic technique and digital image analysis for columnar grain size and relative intercolumnar porosity. Incorporation of the proposed evaluation technique will increase knowledge of the relation between processing parameters and material properties by incorporating a structural link. Application of this evaluation method will directly benefit areas of quality control, microstructural model development, and reduced development time for process scaling

  2. Electron beam physical vapor deposition of thin ruby films for remote temperature sensing

    International Nuclear Information System (INIS)

    Li Wei; Coppens, Zachary J.; Greg Walker, D.; Valentine, Jason G.

    2013-01-01

    Thermographic phosphors (TGPs) possessing temperature-dependent photoluminescence properties have a wide range of uses in thermometry due to their remote access and large temperature sensitivity range. However, in most cases, phosphors are synthesized in powder form, which prevents their use in high resolution micro and nanoscale thermal microscopy. In the present study, we investigate the use of electron beam physical vapor deposition to fabricate thin films of chromium-doped aluminum oxide (Cr-Al 2 O 3 , ruby) thermographic phosphors. Although as-deposited films were amorphous and exhibited weak photoluminescence, the films regained the stoichiometry and α-Al 2 O 3 crystal structure of the combustion synthesized source powder after thermal annealing. As a consequence, the annealed films exhibit both strong photoluminescence and a temperature-dependent lifetime that decreases from 2.9 ms at 298 K to 2.1 ms at 370 K. Ruby films were also deposited on multiple substrates. To ensure a continuous film with smooth surface morphology and strong photoluminescence, we use a sapphire substrate, which is thermal expansion coefficient and lattice matched to the film. These thin ruby films can potentially be used as remote temperature sensors for probing the local temperatures of micro and nanoscale structures.

  3. Failure mechanisms of platinum aluminide bond coat/electron beam-physical vapor deposited thermal barrier coatings

    Science.gov (United States)

    Vaidyanathan, Krishnakumar

    Thermal barrier coatings (TBCs) allow operation of structural components, such as turbine blades and vanes in industrial and aircraft gas engines, at temperatures close to the substrate melting temperatures. They consist of four different layers; a high strength creep-resistant nickel-based superalloy substrate, an oxidation resistant bond coat (BC), a low thermal conductivity ceramic topcoat and a thermally grown oxide (TGO), that is predominantly alpha-Al 2O3, that forms between the BC and the TBC. Compressive stresses (3--5 GPa) that are generated in the thin TGO (0.25--8 mum) due to the mismatch in thermal coefficient of expansion between the TGO and BC play a critical role in the failure of these coatings. In this study, the failure mechanisms of a commercial yttria-stabilized zirconia (7YSZ) electron beam-physical vapor deposited (EB-PVD) coating on platinum aluminide (beta-(Ni,Pt)Al) bond coat have been identified. Two distinct mechanisms have been found responsible for the observed damage initiation and progression at the TGO/bond coat interface. The first mechanism leads to localized debonding at TGO/bond coat interface due to increased out-of-plane tensile stress, along bond coat features that manifest themselves as ridges. The second mechanism causes cavity formation at the TGO/bond coat interface, driven by cyclic plasticity of the bond coat. It has been found that the debonding at the TGO/bond coat interface due to the first mechanism is solely life determining. The final failure occurs by crack extension along either the TGO/bond coat interface or the TGO/YSZ interface or a combination of both, leading to large scale buckling. Based on these mechanisms, it is demonstrated that the bond coat grain size and the aspect ratio of the ridges have a profound influence on spallation lives of the coating. The removal of these ridges by fine polishing prior to TBC deposition led to a four-fold improvement in life. The failure mechanism identified for the

  4. Process-structure-property relationships of micron thick gadolinium oxide films deposited by reactive electron beam-physical vapor deposition (EB-PVD)

    Science.gov (United States)

    Grave, Daniel A.

    Gadolinium oxide (Gd2O3) is an attractive material for solid state neutron detection due to gadolinium's high thermal neutron capture cross section. Development of neutron detectors based on Gd2 O3 requires sufficiently thick films to ensure neutron absorption. In this dissertation work, the process-structure-property relationships of micron thick Gd2O3 films deposited by reactive electron-beam physical vapor deposition (EB-PVD) were studied. Through a systematic design of experiments, fundamental studies were conducted to determine the effects of processing conditions such as deposition temperature, oxygen flow rate, deposition rate, and substrate material on Gd2O3 film crystallographic phase, texture, morphology, grain size, density, and surface roughness. Films deposited at high rates (> 5 A/s) were examined via x-ray diffraction (XRD) and Raman spectroscopy. Quantitative phase volume calculations were performed via a Rietveld refinement technique. All films deposited at high rates were found to be fully monoclinic or mixed cubic/monoclinic phase. Generally, increased deposition temperature and increased oxygen flow resulted in increased cubic phase volume. As film thickness increased, monoclinic phase volume increased. Grazing incidence x-ray diffraction (GIXRD) depth profiling analysis showed that cubic phase was only present under large incidence angle (large penetration depth) measurements, and after a certain point, only monoclinic phase was grown. This was confirmed by transmission electron microscopy (TEM) analysis with selected area diffraction (SAD). Based on this information, a large compressive stress was hypothesized to cause the formation of the monoclinic phase and this hypothesis was confirmed by demonstrating the existence of a stress induced phase transition. An experiment was designed to introduce compressive stress into the Gd2O 3 films via ion beam assisted deposition (IBAD). This allowed for systematic increase in compressive stress while

  5. Silicon-substituted hydroxyapatite coating with Si content on the nanotube-formed Ti–Nb–Zr alloy using electron beam-physical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Yong-Hoon [Division of Restorative, Prosthetic and Primary Care Dentistry, College of Dentistry, The Ohio State University, 305 W. 12th Ave., Columbus, OH (United States); Department of Dental Materials, Research Center of Nano-Interface Activation for Biomaterials, and Research Center for Oral Disease Regulation of the Aged, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Choe, Han-Cheol, E-mail: hcchoe@chosun.ac.kr [Department of Dental Materials, Research Center of Nano-Interface Activation for Biomaterials, and Research Center for Oral Disease Regulation of the Aged, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Brantley, William A. [Division of Restorative, Prosthetic and Primary Care Dentistry, College of Dentistry, The Ohio State University, 305 W. 12th Ave., Columbus, OH (United States)

    2013-11-01

    The purpose of this study was to investigate the electrochemical characteristics of silicon-substituted hydroxyapatite coatings on the nanotube-formed Ti–35Nb–10Zr alloy. The silicon-substituted hydroxyapatite (Si–HA) coatings on the nanotube structure were deposited by electron beam-physical vapor deposition and anodization methods, and biodegradation properties were analyzed by potentiodynamic polarization and electrochemical impedance spectroscopy measurement. The surface characteristics were analyzed by field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction (XRD). The Si–HA layers were deposited with rough features having highly ordered nanotube structures on the titanium alloy substrate. The thickness of the Si–HA coating was less than that of the HA coating. The XRD results confirmed that the Si–HA coating on the nanotube structure consisted of TiO{sub 2} anatase, TiO{sub 2} rutile, hydroxyapatite, and calcium phosphate silicate. The Si–HA coating surface exhibited lower I{sub corr} than the HA coating, and the polarization resistance was increased by substitution of silicon in hydroxyapatite. - Highlights: • Silicon substituted hydroxyapatite (Si–HA) was coated on nanotubular titanium alloy. • The Si–HA coating thickness was less than single hydroxyapatite (HA) coating. • Si–HA coatings consisted of TiO{sub 2}, HA, and Ca{sub 5}(PO{sub 4}){sub 2}SiO{sub 4}. • Polarization resistance of the coating was increased by Si substitution in HA.

  6. Double-ceramic-layer thermal barrier coatings of La{sub 2}Zr{sub 2}O{sub 7}/YSZ deposited by electron beam-physical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Xu Zhenhua [State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Beijing Institute of Aeronautical Materials, Beijing 100095 (China); He Limin; Mu Rende [Beijing Institute of Aeronautical Materials, Beijing 100095 (China); Zhong Xinghua; Zhang Yanfei; Zhang Jiangfeng [State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Cao Xueqiang [State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)], E-mail: xcao@ciac.jl.cn

    2009-04-03

    Double-ceramic-layer (DCL) thermal barrier coatings (TBCs) of La{sub 2}Zr{sub 2}O{sub 7} (LZ) and yttria stabilized zirconia (YSZ) were deposited by electron beam-physical vapor deposition (EB-PVD). The composition, crystal structure, surface and cross-sectional morphologies and cyclic oxidation behavior of the DCL coating were studied. Both the X-ray diffraction (XRD) and thermogravimetric-differential thermal analysis (TG-DTA) prove that LZ and YSZ have good chemical applicability to form a DCL coating. The thermal cycling test at 1373 K in an air furnace indicates the DCL coating has a much longer lifetime than the single layer LZ coating, and even longer than that of the single layer YSZ coating. The failure of the DCL coating is a result of both the bond coat oxidation and the thermal strain between bond coat and ceramic layer generated by the thermal expansion mismatch. Additionally, the compressive stress initiated during cooling is also an important factor to control the cleavage of the interface between the LZ and YSZ coatings. Since no single material that has been studied so far satisfies all the requirements for high temperature TBCs, DCL coating is an important development direction of TBCs.

  7. Double-ceramic-layer thermal barrier coatings based on La{sub 2}(Zr{sub 0.7}Ce{sub 0.3}){sub 2}O{sub 7}/La{sub 2}Ce{sub 2}O{sub 7} deposited by electron beam-physical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Z.H. [Beijing Institute of Aeronautical Materials, Department 5, P.O. Box 81-5, Beijing 100095 (China); State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); He, L.M., E-mail: he_limin@yahoo.com [Beijing Institute of Aeronautical Materials, Department 5, P.O. Box 81-5, Beijing 100095 (China); Mu, R.D.; He, S.M.; Huang, G.H. [Beijing Institute of Aeronautical Materials, Department 5, P.O. Box 81-5, Beijing 100095 (China); Cao, X.Q., E-mail: xcao@ciac.jl.cn [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)

    2010-03-15

    Double-ceramic-layer (DCL) thermal barrier coatings (TBCs) of La{sub 2}(Zr{sub 0.7}Ce{sub 0.3}){sub 2}O{sub 7} (LZ7C3) and La{sub 2}Ce{sub 2}O{sub 7} (LC) were deposited by electron beam-physical vapor deposition (EB-PVD). The composition, interdiffusion, surface and cross-sectional morphologies, cyclic oxidation behavior of DCL coating were studied. Energy dispersive spectroscopy and X-ray diffraction analyses indicate that both LZ7C3 and LC coatings are effectively fabricated by a single LZ7C3 ingot with properly controlling the deposition energy. The chemical compatibility of LC coating and thermally grown oxide (TGO) layer is unstable. LaAlO{sub 3} is formed due to the chemical reaction between LC and Al{sub 2}O{sub 3} which is the main composition of TGO layer. Additionally, the thermal cycling behavior of DCL coating is influenced by the interdiffusion of Zr and Ce between LZ7C3 and LC coatings. The failure of DCL coating is a result of the sintering of LZ7C3 coating surface, the chemical incompatibility of LC coating and TGO layer and the abnormal oxidation of bond coat. Since no single material that has been studied so far satisfies all the requirements for high temperature applications, DCL coating is an important development direction of TBCs.

  8. Novel thermal barrier coatings based on La{sub 2}(Zr{sub 0.7}Ce{sub 0.3}){sub 2}O{sub 7}/8YSZ double-ceramic-layer systems deposited by electron beam physical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Xu Zhenhua, E-mail: zhxuciac@yahoo.com.cn [Beijing Institute of Aeronautical Materials, Department 5, P.O. Box 81-5, Beijing 100095 (China); He Shimei; He Limin; Mu Rende; Huang Guanghong [Beijing Institute of Aeronautical Materials, Department 5, P.O. Box 81-5, Beijing 100095 (China); Cao Xueqiang [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)

    2011-03-17

    Research highlights: > LZ7C3 and YSZ have good chemical compatibility for the formation of DCL coating. > DCL coating has a longer lifetime than that of single layer coating of LZ7C3 or YSZ. > Similar TECs of LZ7C3 with YSZ coatings and YSZ coating with TGO layer. > Unique growth modes of columns within DCL coating. > Outward diffusion of Cr element (bond coat) into LZ7C3 layer. - Abstract: Double-ceramic-layer (DCL) thermal barrier coatings (TBCs) of La{sub 2}(Zr{sub 0.7}Ce{sub 0.3}){sub 2}O{sub 7} (LZ7C3) and yttria stabilized zirconia (YSZ) were deposited by electron beam-physical vapor deposition (EB-PVD). The thermal cycling test at 1373 K in an air furnace indicates the DCL coating has a much longer lifetime than the single layer LZ7C3 coating, and even longer than that of the single layer YSZ coating. The superior sintering-resistance of LZ7C3 coating, the similar thermal expansion behaviors of YSZ interlayer with LZ7C3 coating and thermally grown oxide (TGO) layer, and the unique growth modes of columns within DCL coating are all very helpful to the prolongation of thermal cycling life of DCL coating. The failure of DCL coating is mainly a result of the reduction-oxidation of cerium oxide, the crack initiation, propagation and extension, the abnormal oxidation of bond coat, the degradation of t'-phase in YSZ coating and the outward diffusion of Cr alloying element into LZ7C3 coating.

  9. Directed vapor deposition

    Science.gov (United States)

    Groves, James Frederick

    This dissertation describes the invention, design, construction, experimental evaluation and modeling of a new physical vapor deposition technique (U.S. Patent #5,534,314) for high rate, efficient deposition of refractory elements, alloys, and compounds onto flat or curved surfaces. The new Directed Vapor Deposition (DVD) technique examined in this dissertation was distinct from previous physical vapor deposition techniques because it used low vacuum electron beam (e-beam) evaporation in combination with a carrier gas stream to transport and vapor spray deposit metals, ceramics, and semiconducting materials. Because of the system's unique approach to vapor phase materials processing, detailed analyses of critical concepts (e.g. the e-beam accelerating voltage and power required for evaporation, the vacuum pumping capacity necessary to generate specific gas flow velocities exiting a nozzle) were used to reduce to practice a functioning materials synthesis tool. After construction, the ability to create low contamination films of pure metals, semi-conducting materials, and compounds via this new method was demonstrated, and oxide deposition using an oxygen-doped gas stream in combination with a pure metal evaporant source was shown to be feasible. DVD vapor transport characteristics were experimentally investigated with deposition chamber pressure, carrier gas type, and e-beam power being identified as major processing parameters which affected vapor atom trajectories. The low vacuum carrier gas streams employed in DVD showed a dramatic ability to focus the vapor stream during transport to the substrate and thereby enhance material deposition rates and efficiencies significantly under certain process conditions. Conditions for maximum deposition efficiency onto flat substrates and continuous fibers were experimentally identified by varying chamber pressure, carrier gas velocity (Mach number), and e-beam power. Deposition efficiencies peaked at about 0.5 Torr when

  10. 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…

  11. Chemical vapor deposited boron carbide

    International Nuclear Information System (INIS)

    Mackinnon, I.D.R.; Smith, K.L.

    1987-01-01

    Detailed analytical electron microscope (AEM) studies of yellow whiskers produced by chemical vapor deposition (CVD) show that two basic types of whiskers are produced at low temperatures (between 1200 0 C and 1400 0 C) and low boron to carbon gas ratios. Both whisker types show planar microstructures such as twin planes and stacking faults oriented parallel to, or at a rhombohedral angle to, the growth direction. For both whisker types, the presence of droplet-like terminations containing both Si and Ni indicate that the growth process during CVD is via a vapor-liquid-solid (VLS) mechanisms

  12. Vapor deposition of tantalum and tantalum compounds

    International Nuclear Information System (INIS)

    Trkula, M.

    1996-01-01

    Tantalum, and many of its compounds, can be deposited as coatings with techniques ranging from pure, thermal chemical vapor deposition to pure physical vapor deposition. This review concentrates on chemical vapor deposition techniques. The paper takes a historical approach. The authors review classical, metal halide-based techniques and current techniques for tantalum chemical vapor deposition. The advantages and limitations of the techniques will be compared. The need for new lower temperature processes and hence new precursor chemicals will be examined and explained. In the last section, they add some speculation as to possible new, low-temperature precursors for tantalum chemical vapor deposition

  13. Flowing Afterglow Vapor Deposition for Microelectric Applications.

    Science.gov (United States)

    1987-04-28

    PACVD system it is worthwhile to review briefly the limitations of conventional chemical vapor deposition (CVD) systems, glow discharge deposition...regimes previously inaccessible to MOCVD. III. F. Status of Construction Project As shown in Fig. 8, a good portion of the basic PACVD machine has

  14. Chemical-vapor-deposition reactor

    Science.gov (United States)

    Chern, S.

    1979-01-01

    Reactor utilizes multiple stacked trays compactly arranged in paths of horizontally channeled reactant gas streams. Design allows faster and more efficient deposits of film on substrates, and reduces gas and energy consumption. Lack of dead spots that trap reactive gases reduces reactor purge time.

  15. In-situ formation of multiphase electron beam physical vapor deposited barrier coatings for turbine components

    Science.gov (United States)

    Subramanian, Ramesh

    2001-01-01

    A turbine component (10), such as a turbine blade, is provided which is made of a metal alloy (22) and a base columnar thermal barrier coating (20) on the alloy surface, where a heat resistant ceramic oxide sheath material (32' or 34') covers the columns (28), and the sheath material is the reaction product of a precursor ceramic oxide sheath material and the base thermal barrier coating material.

  16. Plasmon-assisted chemical vapor deposition.

    Science.gov (United States)

    Boyd, David A; Greengard, Leslie; Brongersma, Mark; El-Naggar, Mohamed Y; Goodwin, David G

    2006-11-01

    We introduce a new chemical vapor deposition (CVD) process that can be used to selectively deposit materials of many different types. The technique makes use of the plasmon resonance in nanoscale metal structures to produce the local heating necessary to initiate deposition when illuminated by a focused low-power laser. We demonstrate the technique, which we refer to as plasmon-assisted CVD (PACVD), by patterning the spatial deposition of PbO and TiO(2) on glass substrates coated with a dispersion of 23 nm gold particles. The morphology of both oxide deposits is consistent with local laser-induced heating of the gold particles by more than 150 degrees C. We show that temperature changes of this magnitude are consistent with our analysis of the heat-loss mechanisms. The technique is general and can be used to spatially control the deposition of virtually any material for which a CVD process exists.

  17. Vapor deposition in basaltic stalactites, Kilauea, Hawaii

    Science.gov (United States)

    Baird, A. K.; Mohrig, D. C.; Welday, E. E.

    Basaltic stalacties suspended from the ceiling of a large lava tube at Kilauea, Hawaii, have totally enclosed vesicles whose walls are covered with euhedral FeTi oxide and silicate crystals. The walls of the vesicles and the exterior surfaces of stalactites are Fe and Ti enriched and Si depleted compared to common basalt. Minerals in vesicles have surface ornamentations on crystal faces which include alkali-enriched, aluminosilicate glass(?) hemispheres. No sulfide-, chloride-, fluoride-, phosphate- or carbonate-bearing minerals are present. Minerals in the stalactites must have formed by deposition from an iron oxide-rich vapor phase produced by the partial melting and vaporization of wall rocks in the tube.

  18. Plasma Spray-Physical Vapor Deposition (PS-PVD) of Ceramics for Protective Coatings

    Science.gov (United States)

    Harder, Bryan J.; Zhu, Dongming

    2011-01-01

    In order to generate advanced multilayer thermal and environmental protection systems, a new deposition process is needed to bridge the gap between conventional plasma spray, which produces relatively thick coatings on the order of 125-250 microns, and conventional vapor phase processes such as electron beam physical vapor deposition (EB-PVD) which are limited by relatively slow deposition rates, high investment costs, and coating material vapor pressure requirements. The use of Plasma Spray - Physical Vapor Deposition (PS-PVD) processing fills this gap and allows thin (PVD coater at NASA Glenn Research Center. A design-of-experiments was used to examine the effects of process variables (Ar/He plasma gas ratio, the total plasma gas flow, and the torch current) on chamber pressure and torch power. Coating thickness, phase and microstructure were evaluated for each set of deposition conditions. Low chamber pressures and high power were shown to increase coating thickness and create columnar-like structures. Likewise, high chamber pressures and low power had lower growth rates, but resulted in flatter, more homogeneous layers

  19. Chemical vapor deposition of group IIIB metals

    Science.gov (United States)

    Erbil, A.

    1989-11-21

    Coatings of Group IIIB metals and compounds thereof are formed by chemical vapor deposition, in which a heat decomposable organometallic compound of the formula given in the patent where M is a Group IIIB metal, such as lanthanum or yttrium and R is a lower alkyl or alkenyl radical containing from 2 to about 6 carbon atoms, with a heated substrate which is above the decomposition temperature of the organometallic compound. The pure metal is obtained when the compound of the formula 1 is the sole heat decomposable compound present and deposition is carried out under nonoxidizing conditions. Intermetallic compounds such as lanthanum telluride can be deposited from a lanthanum compound of formula 1 and a heat decomposable tellurium compound under nonoxidizing conditions.

  20. Selective Metal-vapor Deposition on Organic Surfaces.

    Science.gov (United States)

    Tsujioka, Tsuyoshi

    2016-02-01

    Selective metal-vapor deposition signifies that metal-vapor atoms are deposited on a hard organic surface, but not on a soft (low glass transition temperature, low Tg ) surface. In this paper, we introduce the origin, extension, and applications of selective metal-vapor deposition. An amorphous photochromic diarylethene film shows light-controlled selective metal-vapor deposition, which is caused by a large Tg change based on photoisomerization, but various organic surfaces, including organic crystal and polymers, can be utilized for achieving selective metal-vapor deposition. Various applications of selective metal-vapor deposition, including cathode patterning of organic light-emitting devices, micro-thin-film fuses, multifunctional diffraction gratings, in-plane electrical bistability for memory devices, and metal-vapor integration, have been demonstrated. © 2015 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. 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

  2. Origin of Ultrastability in Vapor-Deposited Glasses.

    Science.gov (United States)

    Berthier, Ludovic; Charbonneau, Patrick; Flenner, Elijah; Zamponi, Francesco

    2017-11-03

    Glass films created by vapor-depositing molecules onto a substrate can exhibit properties similar to those of ordinary glasses aged for thousands of years. It is believed that enhanced surface mobility is the mechanism that allows vapor deposition to create such exceptional glasses, but it is unclear how this effect is related to the final state of the film. Here we use molecular dynamics simulations to model vapor deposition and an efficient Monte Carlo algorithm to determine the deposition rate needed to create ultrastable glassy films. We obtain a scaling relation that quantitatively captures the efficiency gain of vapor deposition over bulk annealing, and demonstrates that surface relaxation plays the same role in the formation of vapor-deposited glasses as bulk relaxation does in ordinary glass formation.

  3. Vapor-wall deposition in chambers: theoretical considerations.

    Science.gov (United States)

    McVay, Renee C; Cappa, Christopher D; Seinfeld, John H

    2014-09-02

    In order to constrain the effects of vapor-wall deposition on measured secondary organic aerosol (SOA) yields in laboratory chambers, researchers recently varied the seed aerosol surface area in toluene oxidation and observed a clear increase in the SOA yield with increasing seed surface area (Zhang, X.; et al. Proc. Natl. Acad. Sci. U.S.A. 2014, 111, 5802). Using a coupled vapor-particle dynamics model, we examine the extent to which this increase is the result of vapor-wall deposition versus kinetic limitations arising from imperfect accommodation of organic species into the particle phase. We show that a seed surface area dependence of the SOA yield is present only when condensation of vapors onto particles is kinetically limited. The existence of kinetic limitation can be predicted by comparing the characteristic time scales of gas-phase reaction, vapor-wall deposition, and gas-particle equilibration. The gas-particle equilibration time scale depends on the gas-particle accommodation coefficient αp. Regardless of the extent of kinetic limitation, vapor-wall deposition depresses the SOA yield from that in its absence since vapor molecules that might otherwise condense on particles deposit on the walls. To accurately extrapolate chamber-derived yields to atmospheric conditions, both vapor-wall deposition and kinetic limitations must be taken into account.

  4. Boron carbide whiskers produced by vapor deposition

    Science.gov (United States)

    1965-01-01

    Boron carbide whiskers have an excellent combination of properties for use as a reinforcement material. They are produced by vaporizing boron carbide powder and condensing the vapors on a substrate. Certain catalysts promote the growth rate and size of the whiskers.

  5. Directed Vapor Deposition: Low Vacuum Materials Processing Technology

    National Research Council Canada - National Science Library

    Groves, J. F; Mattausch, G; Morgner, H; Hass, D. D; Wadley, H. N

    2000-01-01

    Directed vapor deposition (DVD) is a recently developed electron beam-based evaporation technology designed to enhance the creation of high performance thick and thin film coatings on small area surfaces...

  6. Gas analysis during the chemical vapor deposition of carbon

    International Nuclear Information System (INIS)

    Lieberman, M.L.; Noles, G.T.

    1973-01-01

    Gas chromatographic analyses were performed during the chemical vapor deposition of carbon in both isothermal and thermal gradient systems. Such data offer insight into the gas phase processes which occur during deposition and the interrelations which exist between gas composition, deposition rate, and resultant structure of the deposit. The results support a carbon CVD model presented previously. The application of chromatographic analysis to research, development, and full-scale facilities is shown. (U.S.)

  7. Processing Research on Chemically Vapor Deposited Silicon Nitride.

    Science.gov (United States)

    1979-12-01

    34 sea urchins ") predominated, suggesting that formation was primarily from the vapor phase with little of the nodular growths seen at only slightly...deposition parameters on crystallite size, morphology and deposition rate. Geometries include a cold-wall, flat plate reactor (CW) and 4-inch and 1-inch...typical crossections of banded deposits and deposits which showed transitions from amorphous to crystalline morphologies , respectively. Figure 2-5

  8. Chemical vapor deposition reactor. [providing uniform film thickness

    Science.gov (United States)

    Chern, S. S.; Maserjian, J. (Inventor)

    1977-01-01

    An improved chemical vapor deposition reactor is characterized by a vapor deposition chamber configured to substantially eliminate non-uniformities in films deposited on substrates by control of gas flow and removing gas phase reaction materials from the chamber. Uniformity in the thickness of films is produced by having reactive gases injected through multiple jets which are placed at uniformally distributed locations. Gas phase reaction materials are removed through an exhaust chimney which is positioned above the centrally located, heated pad or platform on which substrates are placed. A baffle is situated above the heated platform below the mouth of the chimney to prevent downdraft dispersion and scattering of gas phase reactant materials.

  9. Chemical vapor deposition of graphene single crystals.

    Science.gov (United States)

    Yan, Zheng; Peng, Zhiwei; Tour, James M

    2014-04-15

    As a two-dimensional (2D) sp(2)-bonded carbon allotrope, graphene has attracted enormous interest over the past decade due to its unique properties, such as ultrahigh electron mobility, uniform broadband optical absorption and high tensile strength. In the initial research, graphene was isolated from natural graphite, and limited to small sizes and low yields. Recently developed chemical vapor deposition (CVD) techniques have emerged as an important method for the scalable production of large-size and high-quality graphene for various applications. However, CVD-derived graphene is polycrystalline and demonstrates degraded properties induced by grain boundaries. Thus, the next critical step of graphene growth relies on the synthesis of large graphene single crystals. In this Account, we first discuss graphene grain boundaries and their influence on graphene's properties. Mechanical and electrical behaviors of CVD-derived polycrystalline graphene are greatly reduced when compared to that of exfoliated graphene. We then review four representative pathways of pretreating Cu substrates to make millimeter-sized monolayer graphene grains: electrochemical polishing and high-pressure annealing of Cu substrate, adding of additional Cu enclosures, melting and resolidfying Cu substrates, and oxygen-rich Cu substrates. Due to these pretreatments, the nucleation site density on Cu substrates is greatly reduced, resulting in hexagonal-shaped graphene grains that show increased grain domain size and comparable electrical properties as to exfoliated graphene. Also, the properties of graphene can be engineered by its shape, thickness and spatial structure. Thus, we further discuss recently developed methods of making graphene grains with special spatial structures, including snowflakes, six-lobed flowers, pyramids and hexagonal graphene onion rings. The fundamental growth mechanism and practical applications of these well-shaped graphene structures should be interesting topics and

  10. Impurities in chromium deposits produced by electroplating and physical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Dini, J.W.

    1994-05-01

    Impurity contents in electrodeposited (hexavalent and trivalent) chromium deposits and physically vapor deposited (thermal evaporation, electron beam evaporation and rf-sputtering) were compared. Oxygen is the key impurity obtained in electrodeposited films but it can be minimized in hexavalent plating solutions by operating at high temperature, e. g., 85 C. Electrodeposits produced in trivalent chromium plating solutions and physically vapor deposited films have much higher oxygen contents than electrodeposits produced in hexavalent chromium solutions operated at temperatures around 85 C. Depending on the target material used for physically vapor deposited films, these films can also have high amounts of other impurities.

  11. Ti-doped hydrogenated diamond like carbon coating deposited by hybrid physical vapor deposition and plasma enhanced chemical vapor deposition

    Science.gov (United States)

    Lee, Na Rae; Sle Jun, Yee; Moon, Kyoung Il; Sunyong Lee, Caroline

    2017-03-01

    Diamond-like carbon films containing titanium and hydrogen (Ti-doped DLC:H) were synthesized using a hybrid technique based on physical vapor deposition (PVD) and plasma enhanced chemical vapor deposition (PECVD). The film was deposited under a mixture of argon (Ar) and acetylene gas (C2H2). The amount of Ti in the Ti-doped DLC:H film was controlled by varying the DC power of the Ti sputtering target ranging from 0 to 240 W. The composition, microstructure, mechanical and chemical properties of Ti-doped DLC:H films with varying Ti concentrations, were investigated using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), nano indentation, a ball-on-disk tribometer, a four-point probe system and dynamic anodic testing. As a result, the optimum composition of Ti in Ti-doped DLC:H film using our hybrid method was found to be a Ti content of 18 at. %, having superior electrical conductivity and high corrosion resistance, suitable for bipolar plates. Its hardness value was measured to be 25.6 GPa with a low friction factor.

  12. Thermal barrier coating by electron beam-physical vapor deposition of zirconia co-doped with yttria and niobia

    Directory of Open Access Journals (Sweden)

    Daniel Soares de Almeida

    2010-08-01

    Full Text Available The most usual ceramic material for coating turbine blades is yttria doped zirconia. Addition of niobia, as a co-dopant in the Y2O3-ZrO2 system, can reduce the thermal conductivity and improve mechanical properties of the coating. The purpose of this work was to evaluate the influence of the addition of niobia on the microstructure and thermal properties of the ceramic coatings. SEM on coatings fractured cross-section shows a columnar structure and the results of XRD show only zirconia tetragonal phase in the ceramic coating for the chemical composition range studied. As the difference NbO2,5-YO1,5 mol percent increases, the tetragonality increases. A significant reduction of the thermal conductivity, measured by laser flash technique in the zirconia coating co-doped with yttria and niobia when compared with zirconia-yttria coating was observed.

  13. Laser-induced chemical vapor deposition reactions

    International Nuclear Information System (INIS)

    Teslenko, V.V.

    1990-01-01

    The results of investigation of chemical reactions of deposition of different substances from the gas phase when using the energy of pulse quasicontinuous and continuous radiation of lasers in the wave length interval from 0.193 to 10.6 μm are generalized. Main attetion is paid to deposition of inorganic substances including nonmetals (C, Si, Ge and others), metals (Cu, Au, Zn, Cd, Al, Cr, Mo, W, Ni) and some simple compounds. Experimental data on the effect of laser radiation parameters and reagent nature (hydrides, halogenides, carbonyls, alkyl organometallic compounds and others) on the deposition rate and deposit composition are described in detail. Specific features of laser-chemical reactions of deposition and prospects of their application are considered

  14. Understanding the chemical vapor deposition of diamond: recent progress

    International Nuclear Information System (INIS)

    Butler, J E; Mankelevich, Y A; Cheesman, A; Ma, Jie; Ashfold, M N R

    2009-01-01

    In this paper we review and provide an overview to the understanding of the chemical vapor deposition (CVD) of diamond materials with a particular focus on the commonly used microwave plasma-activated chemical vapor deposition (MPCVD). The major topics covered are experimental measurements in situ to diamond CVD reactors, and MPCVD in particular, coupled with models of the gas phase chemical and plasma kinetics to provide insight into the distribution of critical chemical species throughout the reactor, followed by a discussion of the surface chemical process involved in diamond growth.

  15. Chemical vapor deposition of nanocrystalline diamond films

    International Nuclear Information System (INIS)

    Vyrovets, I.I.; Gritsyna, V.I.; Dudnik, S.F.; Opalev, O.A.; Reshetnyak, O.M.; Strel'nitskij, V.E.

    2008-01-01

    The brief review of the literature is devoted to synthesis of nanocrystalline diamond films. It is shown that the CVD method is an effective way for deposition of such nanostructures. The basic technological methods that allow limit the size of growing diamond crystallites in the film are studied.

  16. Fabrication and evaluation of chemically vapor deposited tungsten heat pipe.

    Science.gov (United States)

    Bacigalupi, R. J.

    1972-01-01

    A network of lithium-filled tungsten heat pipes is being considered as a method of heat extraction from high temperature nuclear reactors. The need for material purity and shape versatility in these applications dictates the use of chemically vapor deposited (CVD) tungsten. Adaptability of CVD tungsten to complex heat pipe designs is shown. Deposition and welding techniques are described. Operation of two lithium-filled CVD tungsten heat pipes above 1800 K is discussed.

  17. Chemical vapor deposition of fluorine-doped zinc oxide

    Science.gov (United States)

    Gordon, Roy G.; Kramer, Keith; Liang, Haifan

    2000-06-06

    Fims of fluorine-doped zinc oxide are deposited from vaporized precursor compounds comprising a chelate of a dialkylzinc, such as an amine chelate, an oxygen source, and a fluorine source. The coatings are highly electrically conductive, transparent to visible light, reflective to infrared radiation, absorbing to ultraviolet light, and free of carbon impurity.

  18. Chemical vapor deposition: A technique for applying protective coatings

    Energy Technology Data Exchange (ETDEWEB)

    Wallace, T.C. Sr.; Bowman, M.G.

    1979-01-01

    Chemical vapor deposition is discussed as a technique for applying coatings for materials protection in energy systems. The fundamentals of the process are emphasized in order to establish a basis for understanding the relative advantages and limitations of the technique. Several examples of the successful application of CVD coating are described. 31 refs., and 18 figs.

  19. 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…

  20. 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...

  1. Dynamics of faceted thin films formation during vapor deposition

    Science.gov (United States)

    Li, Kun-Dar; Huang, Po-Yu

    2018-01-01

    In this study, an anisotropic phase-field model was established to simulate the growth of crystalline thin films during vapor deposition. The formation and evolution of characteristic surface with faceted morphologies were demonstrated, in accordance with the regularly obtained microstructure in the actual experiments. In addition, the influences of deposition parameters, such as the deposition rate and the interfacial energy, on the formation mechanism of the characteristic morphology were also illustrated. While a relatively low surface energy of substrate was regarded, the faceted islands were formed, owing to the anisotropic interfacial energy of thin films. In the condition of a high surface energy of substrate, the layered structures of deposited films were produced, which was corresponding to the Frank–van der Merwe growth mode. As various deposition rates were utilized in the numerical simulations, diverse surface morphologies were developed on the basis of the dominant mechanisms, correlating with the adatom diffusion and the deposition kinetics. According to the calculation results, it was observed that a surface character with flattened morphology was generally driven by the adatom diffusion, while the factor of the deposition kinetics was inclined to roughen the surface of thin films. These numerical simulations enhanced the knowledge of thin film growth and facilitated the progress of the vapor deposition technology for advanced applications.

  2. Tandem solar cells deposited using hot-wire chemical vapor deposition

    NARCIS (Netherlands)

    Veen, M.K. van

    2003-01-01

    In this thesis, the application of the hot-wire chemical vapor deposition (HWCVD) technique for the deposition of silicon thin films is described. The HWCVD technique is based on the dissociation of silicon-containing gasses at the catalytic surface of a hot filament. Advantages of this technique

  3. Chemical vapor deposition (CVD) of uranium for alpha spectrometry

    International Nuclear Information System (INIS)

    Ramirez V, M. L.; Rios M, C.; Ramirez O, J.; Davila R, J. I.; Mireles G, F.

    2015-09-01

    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)

  4. Dynamical heterogeneity in a vapor-deposited polymer glass

    Science.gov (United States)

    Zhang, Wengang; Douglas, Jack F.; Starr, Francis W.

    2017-05-01

    Recently, there has been great interest in "ultrastable" glasses formed via vapor deposition, both because of emerging engineering applications of these materials (e.g., active layers in light-emitting diodes and photovoltaics) and, theoretically, as materials for probing the equilibrium properties of glassy materials below their glass transition, based on the conjecture that these materials are equivalent to glassy materials aged over astronomical time scales. We use molecular dynamics simulations to examine the properties of ultrastable vapor-deposited and ordinary polymer glasses. Based on the difference in the energy of the deposited and ordinary films, we estimate the effective cooling rate for the vapor deposited films to be 1 to 3 orders of magnitude larger than that of the ordinary film, depending on the deposition temperature. Similarly, we find an increase in the average segmental relaxation time of the vapor-deposited film compared to the ordinary glass. On the other hand, the normal mode spectrum is essentially identical for the vapor-deposited and the ordinary glass film, suggesting that the high-frequency dynamics should be similar. In short, the segmental relaxation dynamics of the polymer vapor-deposited glass are consistent with those of an ordinary polymer glass with a somewhat slower effective cooling rate. Of course, one would expect a larger effect on dynamics approaching the experimental glass transition, where the cooling rates are much slower than accessible in simulation. To more precisely probe the relationship between the dynamics of these glasses, we examine dynamical heterogeneity within the film. Due to the substantial mobility gradient in the glassy films, we find that it is crucial to distinguish the dynamics of the middle part of the film from those of the entire film. Considering the film as a whole, the average dynamical heterogeneity is dominated by the mobility gradient, and as a consequence the heterogeneity is nearly

  5. Dynamical heterogeneity in a vapor-deposited polymer glass.

    Science.gov (United States)

    Zhang, Wengang; Douglas, Jack F; Starr, Francis W

    2017-05-28

    Recently, there has been great interest in "ultrastable" glasses formed via vapor deposition, both because of emerging engineering applications of these materials (e.g., active layers in light-emitting diodes and photovoltaics) and, theoretically, as materials for probing the equilibrium properties of glassy materials below their glass transition, based on the conjecture that these materials are equivalent to glassy materials aged over astronomical time scales. We use molecular dynamics simulations to examine the properties of ultrastable vapor-deposited and ordinary polymer glasses. Based on the difference in the energy of the deposited and ordinary films, we estimate the effective cooling rate for the vapor deposited films to be 1 to 3 orders of magnitude larger than that of the ordinary film, depending on the deposition temperature. Similarly, we find an increase in the average segmental relaxation time of the vapor-deposited film compared to the ordinary glass. On the other hand, the normal mode spectrum is essentially identical for the vapor-deposited and the ordinary glass film, suggesting that the high-frequency dynamics should be similar. In short, the segmental relaxation dynamics of the polymer vapor-deposited glass are consistent with those of an ordinary polymer glass with a somewhat slower effective cooling rate. Of course, one would expect a larger effect on dynamics approaching the experimental glass transition, where the cooling rates are much slower than accessible in simulation. To more precisely probe the relationship between the dynamics of these glasses, we examine dynamical heterogeneity within the film. Due to the substantial mobility gradient in the glassy films, we find that it is crucial to distinguish the dynamics of the middle part of the film from those of the entire film. Considering the film as a whole, the average dynamical heterogeneity is dominated by the mobility gradient, and as a consequence the heterogeneity is nearly

  6. Effect of vapor-phase oxygen on chemical vapor deposition growth of graphene

    Science.gov (United States)

    Terasawa, Tomo-o.; Saiki, Koichiro

    2015-03-01

    To obtain a large-area single-crystal graphene, chemical vapor deposition (CVD) growth on Cu is considered the most promising. Recently, the surface oxygen on Cu has been found to suppress the nucleation of graphene. However, the effect of oxygen in the vapor phase was not elucidated sufficiently. Here, we investigate the effect of O2 partial pressure (PO2) on the CVD growth of graphene using radiation-mode optical microscopy. The nucleation density of graphene decreases monotonically with PO2, while its growth rate reaches a maximum at a certain pressure. Our results indicate that PO2 is an important parameter to optimize in the CVD growth of graphene.

  7. Kinetics of chemical vapor deposition of boron on molybdenum

    International Nuclear Information System (INIS)

    Tanaka, W.; Nakaanishi, N.; Kato, E.

    1987-01-01

    Experimental rate data of chemical vapor deposition of boron by reduction of boron trichloride with hydrogen are analyzed to determine the reaction mechanism. The reaction orders with respect to the partial pressures of hydrogen and boron trichloride are one half and one third, respectively. It has been found that the outer layer of a deposited film is Mo/sub 2/B/sub 5/ and the inner layer is MoB by the use of X-ray diffraction and EPMA line analysis

  8. Combustion chemical vapor deposited coatings for thermal barrier coating systems

    Energy Technology Data Exchange (ETDEWEB)

    Hampikian, J.M.; Carter, W.B. [Georgia Institute of Technology, Atlanta, GA (United States). School of Materials Science and Engineering

    1995-12-31

    The new deposition process, combustion chemical vapor deposition, shows a great deal of promise in the area of thermal barrier coating systems. This technique produces dense, adherent coatings, and does not require a reaction chamber. Coatings can therefore be applied in the open atmosphere. The process is potentially suitable for producing high quality CVD coatings for use as interlayers between the bond coat and thermal barrier coating, and/or as overlayers, on top of thermal barrier coatings. In this report, the evaluation of alumina and ceria coatings on a nickel-chromium alloy is described.

  9. Chemical vapor deposition of cadmium tellurium films for photovoltaic devices

    International Nuclear Information System (INIS)

    Chu, S.S.; Chu, T.L.; Han, K.D.; Liu, Y.Z.; Mantravadi, M.

    1987-01-01

    Cadmium telluride films have been deposited by chemical vapor deposition (CVD) and close-spaced sublimation (CSS), and their structural and electrical properties have been characterized in detail. The CVD technique has the advantage of controlling the electrical resistivity of p-CdTe films while the CST technique is capable of depositing p-CdTe films at high rates. Thin film heterojunction solar cells of the configuration p-CdTe/CdS/SnO/sub 2/:F/glass have been prepared by the deposition techniques. Solar cells of 1 cm/sup 2/ or larger in area with AM1.5 (global) efficiency of 10.5% have been prepared

  10. Preparation of hafnium carbide by chemical vapor deposition

    International Nuclear Information System (INIS)

    Hertz, Dominique.

    1974-01-01

    Hard, adhesive coatings of single-phase hafnium carbide were obtained by chemical vapor reaction in an atmosphere containing hafnium tetrachloride, methane and a large excess of hydrogen. By varying the gas phase composition and temperature the zones of formation of the different solid phases were studied and the growth of elementary hafnium and carbon deposits evaluated separately. The results show that the mechanism of hafnium carbide deposition does not hardly involve phenomene of homogeneous-phase methane decomposition or tetrachloride reduction by hydrogen unless the atmosphere is very rich or very poor in methane with respect to tetrachloride. However, hydrogen acting inversely on these two reactions, affects the stoichiometry of the substance deposited. The methane decomposition reaction is fairly slow, the reaction leading to hafnium carbide deposition is faster and that of tetrachloride reduction by hydrogen is quite fast [fr

  11. Polyamic acid coating of microspheres by oriented thermal vapor deposition

    International Nuclear Information System (INIS)

    Huang Yong; Zhang Zhanwen; Liu Yiyang; Li Bo; Chen Shufen; Qi Xiaobo

    2011-01-01

    In this paper, a study on the oriented thermal vapor deposition device which is used for coating microspheres with polyamic acid (PAA) is developed. Influences of the processing of monomer material and the adjusting of heating process on the deposition rate are discussed. Two different monomers are poured into two evaporators and evaporated independently, the deposition rate and film thickness are measured via two film thickness measuring probes with the crystal vibration. Space position and symmetry of sample pan, two probes and the oriented tube tip are adjusted so that two monomers' deposition ratio approximates to stoichiometric ratio. High quality coating of PAA on poly-alpha-methylstyrene microsphere is acquired by intermittent piezoelectricity vibration or striking which accompanies rotating of the sample pan. (authors)

  12. Modeling of flame assisted chemical vapor deposition of silicon films

    Energy Technology Data Exchange (ETDEWEB)

    Masi, M.; Cavallotti, C.; Raffa, E. [Dipartimento di Chimica, Materiali e Ingegneria Chimica, Politecnico di Milano, via Mancinelli 7, 20131 Milano (Italy)

    2011-08-15

    The simulation of a flame assisted chemical vapor deposition (FACVD) process is here proposed with reference to the growth of silicon thin films through the silane/chlorosilanes/hydrogen/chlorine route. The goal is to design a reactor able to deposit micromorphous or multicrystalline films at the high growth rates necessary for photovoltaic applications. In fact, since FACVD processes can operate in atmospheric conditions and in auto-thermal mode, they present significant energetic advantages with respect to the plasma assisted technology used today. This work is in particular devoted to illustrate the multi-hierarchical modeling procedure adopted to determine the process optimal operating conditions and to design the deposition chamber. Different burner geometries (single, porous or multiple nozzles burner) were investigated in order to exploit the advantages of the two classical stagnation flow and Bunsen stretched flames. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Kinetics, Chemistry, and Morphology of Syngas Photoinitiated Chemical Vapor Deposition.

    Science.gov (United States)

    Farhanian, Donya; De Crescenzo, Gregory; Tavares, Jason R

    2017-02-28

    Syngas is the product of gasification processes and is used for the production of petrochemicals. Little attention has been paid to its use in the production of oligomeric thin films under ambient conditions. Herein, the nature of the photoinitiated chemical vapor deposition of films made from syngas using high-wavelength ultraviolet light is discussed, including an exploration of the oligomeric films' structure, synthesis mechanism, and growth kinetics. Specifically, X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry analyses provide insight into the chemical structure, illustrating the effect of photogenerated radicals in the formation of aliphatic, anhydride, and cyclic structures. The films are covalently bonded to the substrate and chemically uniform. Electron and atomic force microscopy identify an islandlike morphology for the deposit. These insights into the mechanism and structure are linked to processing parameters through a study on the effect of residence time and treatment duration on the deposition rate, as determined through profilometry.

  14. Water-Assisted Vapor Deposition of PEDOT Thin Film.

    Science.gov (United States)

    Goktas, Hilal; Wang, Xiaoxue; Ugur, Asli; Gleason, Karen K

    2015-07-01

    The synthesis and characterization of poly(3,4-ethylenedioxythiophene) (PEDOT) using water-assisted vapor phase polymerization (VPP) and oxidative chemical vapor deposition (oCVD) are reported. For the VPP PEDOT, the oxidant, FeCl3 , is sublimated onto the substrate from a heated crucible in the reactor chamber and subsequently exposed to 3,4-ethylenedioxythiophene (EDOT) monomer and water vapor in the same reactor. The oCVD PEDOT was produced by introducing the oxidant, EDOT monomer, and water vapor simultaneously to the reactor. The enhancement of doping and crystallinity is observed in the water-assisted oCVD thin films. The high doping level observed at UV-vis-NIR spectra for the oCVD PEDOT, suggests that water acts as a solubilizing agent for oxidant and its byproducts. Although the VPP produced PEDOT thin films are fully amorphous, their conductivities are comparable with that of the oCVD produced ones. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Low temperature synthesis of Zn nanowires by physical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, Philipp; Kast, Michael; Brueckl, Hubert [Austrian Research Centers GmbH ARC, Nano- Systemtechnologies, Donau-City-Strasse 1, A-1220 Wien (Austria)

    2007-07-01

    We demonstrate catalytic growth of zinc nanowires by physical vapor deposition at modest temperatures of 125-175 C on various substrates. In contrast to conventional approaches using tube furnaces our home-built growth system allows to control the vapor sources and the substrate temperature separately. The silicon substrates were sputter coated with a thin gold layer as metal catalyst. The samples were heated to the growth temperature and subsequently exposed to the zinc vapor at high vacuum conditions. The work pressure was adjusted by the partial pressure of oxygen or argon flow gas. Scanning electron microscopy and atomic force microscopy characterizations revealed that the nanowires exhibit straight, uniform morphology and have diameters in the range of 50-350 nm and lengths up to 70 {mu}m. The Zn nanowires grow independently of the substrates crystal orientation via a catalytic vapor-solid growth mechanism. Since no nanowire formation was observed without gold coating, we expect that the onedimensional growth is initiated by a surface reactive Au seed. ZnO nanowires can be produced in the same preparation chamber by oxidation at 500 C in 1atm (80% Ar, 20% O{sub 2}) for 1 hour. ZnO is highly attractive for sensor applications.

  16. Center for Beam Physics, 1992

    International Nuclear Information System (INIS)

    1993-06-01

    This report contains the following information on the center for beam physics: Facilities; Organizational Chart; Roster; Profiles of Staff; Affiliates; Center Publications (1991--1993); and 1992 Summary of Activities

  17. Center for Beam Physics, 1992

    Energy Technology Data Exchange (ETDEWEB)

    1993-06-01

    This report contains the following information on the center for beam physics: Facilities; Organizational Chart; Roster; Profiles of Staff; Affiliates; Center Publications (1991--1993); and 1992 Summary of Activities.

  18. Method of physical vapor deposition of metal oxides on semiconductors

    Science.gov (United States)

    Norton, David P.

    2001-01-01

    A process for growing a metal oxide thin film upon a semiconductor surface with a physical vapor deposition technique in a high-vacuum environment and a structure formed with the process involves the steps of heating the semiconductor surface and introducing hydrogen gas into the high-vacuum environment to develop conditions at the semiconductor surface which are favorable for growing the desired metal oxide upon the semiconductor surface yet is unfavorable for the formation of any native oxides upon the semiconductor. More specifically, the temperature of the semiconductor surface and the ratio of hydrogen partial pressure to water pressure within the vacuum environment are high enough to render the formation of native oxides on the semiconductor surface thermodynamically unstable yet are not so high that the formation of the desired metal oxide on the semiconductor surface is thermodynamically unstable. Having established these conditions, constituent atoms of the metal oxide to be deposited upon the semiconductor surface are directed toward the surface of the semiconductor by a physical vapor deposition technique so that the atoms come to rest upon the semiconductor surface as a thin film of metal oxide with no native oxide at the semiconductor surface/thin film interface. An example of a structure formed by this method includes an epitaxial thin film of (001)-oriented CeO.sub.2 overlying a substrate of (001) Ge.

  19. Microstructure Evolution of Electron Beam Physical Vapour Deposited Ni-23.5Cr-2.66Co-1.44Al Superalloy Sheet During Annealing at 600 °C

    Directory of Open Access Journals (Sweden)

    Li Mingwei

    2013-02-01

    Full Text Available Microstructure evolution of electron beam physical vapour deposited (EB-PVD Ni‑23.5Cr‑2.66Co‑1.44Al superalloy sheet during annealing at 600 °C was investigated. The results showed that the as-deposited alloy was composed of only g phase. After annealing at 600 °C, the locations of diffraction peaks were still the same. The (220 diffraction peak of the deposition side increased with annealing time. The sheet on deposited side had a tendency toward forming (220 texture during post-annealing. No obvious texture was observed at as-deposited and annealed sheet at 600 °C in substrate side. The count and size of "voids" decreased with time. The size of grains increased obviously with annealing time. The ultimate tensile strength of EB-PVD Ni-23.5Cr-2.66Co-1.44Al alloy sheet increased from 641 MPa to 829 MPa after annealing at 600 °C for 30 hours.

  20. The versatility of hot-filament activated chemical vapor deposition

    International Nuclear Information System (INIS)

    Schaefer, Lothar; Hoefer, Markus; Kroeger, Roland

    2006-01-01

    In the field of activated chemical vapor deposition (CVD) of polycrystalline diamond films, hot-filament activation (HF-CVD) is widely used for applications where large deposition areas are needed or three-dimensional substrates have to be coated. We have developed processes for the deposition of conductive, boron-doped diamond films as well as for tribological crystalline diamond coatings on deposition areas up to 50 cm x 100 cm. Such multi-filament processes are used to produce diamond electrodes for advanced electrochemical processes or large batches of diamond-coated tools and parts, respectively. These processes demonstrate the high degree of uniformity and reproducibility of hot-filament CVD. The usability of hot-filament CVD for diamond deposition on three-dimensional substrates is well known for CVD diamond shaft tools. We also develop interior diamond coatings for drawing dies, nozzles, and thread guides. Hot-filament CVD also enables the deposition of diamond film modifications with tailored properties. In order to adjust the surface topography to specific applications, we apply processes for smooth, fine-grained or textured diamond films for cutting tools and tribological applications. Rough diamond is employed for grinding applications. Multilayers of fine-grained and coarse-grained diamond have been developed, showing increased shock resistance due to reduced crack propagation. Hot-filament CVD is also used for in situ deposition of carbide coatings and diamond-carbide composites, and the deposition of non-diamond, silicon-based films. These coatings are suitable as diffusion barriers and are also applied for adhesion and stress engineering and for semiconductor applications, respectively

  1. 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

  2. The Corrosion Protection of Metals by Ion Vapor Deposited Aluminum

    Science.gov (United States)

    Danford, M. D.

    1993-01-01

    A study of the corrosion protection of substrate metals by ion vapor deposited aluminum (IVD Al) coats has been carried out. Corrosion protection by both anodized and unanodized IVD Al coats has been investigated. Base metals included in the study were 2219-T87 Al, 7075-T6 Al, Titanium-6 Al-4 Vanadium (Ti-6Al-4V), 4130 steel, D6AC steel, and 4340 steel. Results reveal that the anodized IVD Al coats provide excellent corrosion protection, but good protection is also achieved by IVD Al coats that have not been anodized.

  3. Thermodynamic calculations for chemical vapor deposition of silicon carbide

    International Nuclear Information System (INIS)

    Minato, Kazuo; Fukuda, Kousaku; Ikawa, Katsuichi

    1985-03-01

    The composition of vapor and condensed phases at equilibrium and CVD phase diagrams were calculated for the CH 3 SiCl 3 -H 2 -Ar system using a computer code SOLGASMIX-PV, which is based on the free energy minimization method. These calculations showed that β-SiC, β-SiC+C(s), β-SiC+Si(s), β-SiC+Si(l), Si(s), Si(l), or C(s) would be deposited depending on deposition parameters. In the CH 3 SiCl 3 -Ar system, condensed phase was found to be β-SiC+C(s) or C(s). Comparing the calculated CVD phase diagrams with the experimental results from the literature, β-SiC+C(s) and β-SiC+Si(s) were deposited in the experiments at the high temperature (more than 2000K) and low temperature (less than 1700K) parts of a resion, respectively, where only β-SiC would be deposited in the calculations. These are remakable results to consider the deposition mechanism of silicon carbide. (author)

  4. Kinetics of chemical vapor deposition of boron on molybdenum

    International Nuclear Information System (INIS)

    Tanaka, H.; Nakanishi, N.; Kato, E.

    1987-01-01

    Experimental rate data of chemical vapor deposition of boron by reduction of boron trichloride with hydrogen are analyzed to determine the reaction mechanism. The experiments were conducted at atmospheric pressure. The weight change of the sample was noted by means of a thermobalance. Molybdenum was used as the substrate. It has been found that the outer layer of the deposited film is Mo/sub 2/B/sub 5/ and the inner layer is MoB, and in the stational state of the reaction, the diffusion in the solid state is considered not to be rate controlling. When mass transport limitation was absent, the reaction orders with respect to boron trichloride and hydrogen were one third and one half, respectively. By comparing these orders with those obtained from Langmuir-Hinshelwood type equations, the rate controlling mechanism is identified to be the desorption of hydrogen chloride from the substrate

  5. New luminescence lines in nanodiamonds obtained by chemical vapor deposition

    Science.gov (United States)

    Golubev, V. G.; Grudinkin, S. A.; Davydov, V. Yu.; Smirnov, A. N.; Feoktistov, N. A.

    2017-12-01

    The spectral characteristics of the photoluminescence lines detected for nanodiamonds obtained by the reactive ion etching of diamond particles in oxygen plasma, deposited by chemical vapor deposition on a silicon substrate, are studied. At room temperature, narrow lines are observed in the visible and infrared spectral regions, with a full width at half-maximum in the range of 1-2 nm at an almost complete absence of a broadband photoluminescence background signal. At decreasing temperature, the lines narrowed to 0.2-0.6 nm at T = 79 K, and the minimum line width was 0.055 nm at T = 10 K. With increasing temperature, the narrow lines shifted to the long-wavelength region of the spectrum, and their intensity decreased.

  6. Chemical vapor deposited fiber coatings and chemical vapor infiltrated ceramic matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Kmetz, M.A.

    1992-01-01

    Conventional Chemical Vapor Deposition (CVD) and Organometallic Chemical Vapor Deposition (MOCVD) were employed to deposit a series of interfacial coatings on SiC and carbon yarn. Molybdenum, tungsten and chromium hexacarbonyls were utilized as precursors in a low temperature (350[degrees]C) MOCVD process to coat SiC yarn with Mo, W and Cr oxycarbides. Annealing studies performed on the MoOC and WOC coated SiC yarns in N[sub 2] to 1,000[degrees]C establish that further decomposition of the oxycarbides occurred, culminating in the formation of the metals. These metals were then found to react with Si to form Mo and W disilicide coatings. In the Cr system, heating in N[sub 2] above 800[degrees]C resulted in the formation of a mixture of carbides and oxides. Convention CVD was also employed to coat SiC and carbon yarn with C, Bn and a new interface designated BC (a carbon-boron alloy). The coated tows were then infiltrated with SiC, TiO[sub 2], SiO[sub 2] and B[sub 4]C by a chemical vapor infiltration process. The B-C coatings were found to provide advantageous interfacial properties over carbon and BN coatings in several different composite systems. The effectiveness of these different coatings to act as a chemically inert barrier layer and their relationship to the degree of interfacial debonding on the mechanical properties of the composites were examined. The effects of thermal stability and strength of the coated fibers and composites were also determined for several difference atmospheres. In addition, a new method for determining the tensile strength of the as-received and coated yarns was also developed. The coated fibers and composites were further characterized by AES, SEM, XPS, IR and X-ray diffraction analysis.

  7. TEXTILE SURFACE MODIFICATION BY PYHSICAL VAPOR DEPOSITION – (REVIEW

    Directory of Open Access Journals (Sweden)

    YUCE Ismail

    2017-05-01

    Full Text Available Textile products are used in various branches of the industry from automotive to space products. Textiles produced for industrial use are generally referred to as technical textiles. Technical textiles are nowadays applied to several areas including transportation, medicine, agriculture, protection, sports, packaging, civil engineering and industry. There are rapid developments in the types of materials used in technical textiles. Therefore, modification and functionalization of textile surfaces is becoming more crucial. The improvements of the properties such as anti-bacterial properties, fire resistivity, UV radiation resistance, electrical conductivity, self cleaning, and super hydrophobic, is getting more concern with respect to developments in textile engineering. The properties of textile surfaces are closely related to the fiber structure, the differences in the polymer composition, the fiber mixture ratio, and the physical and chemical processes applied. Textile surface modifications can be examined in four groups under the name mechanical, chemical, burning and plasma. Surface modifications are made to improve the functionality of textile products. Textile surface modifications affect the properties of the products such as softness, adhesion and wettability. The purpose of this work is to reveal varieties of vapor deposition modifications to improve functionality. For this purpose, the pyhsical vapor deposition methods, their affects on textile products and their end-uses will be reviewed.

  8. Chemical vapor deposition of refractory metals and ceramics III

    International Nuclear Information System (INIS)

    Gallois, B.M.; Lee, W.Y.; Pickering, M.A.

    1995-01-01

    The papers contained in this volume were originally presented at Symposium K on Chemical Vapor Deposition of Refractory Metals and Ceramics III, held at the Fall Meeting of the Materials Research Society in Boston, Massachusetts, on November 28--30, 1994. This symposium was sponsored by Morton International Inc., Advanced Materials, and by The Department of Energy-Oak Ridge National Laboratory. The purpose of this symposium was to exchange scientific information on the chemical vapor deposition (CVD) of metallic and ceramic materials. CVD technology is receiving much interest in the scientific community, in particular, to synthesize new materials with tailored chemical composition and physical properties that offer multiple functionality. Multiphase or multilayered films, functionally graded materials (FGMs), ''smart'' material structures and nanocomposites are some examples of new classes of materials being produced via CVD. As rapid progress is being made in many interdisciplinary research areas, this symposium is intended to provide a forum for reporting new scientific results and addressing technological issues relevant to CVD materials and processes. Thirty four papers have been processed separately for inclusion on the data base

  9. Physically vapor deposited coatings on tools: performance and wear phenomena

    International Nuclear Information System (INIS)

    Koenig, W.; Fritsch, R.; Kammermeier, D.

    1991-01-01

    Coatings produced by physical vapor deposition (PVD) enhance the performance of tools for a broad variety of production processes. In addition to TiN, nowadays (Ti,Al)N and Ti(C,N) coated tools are available. This gives the opportunity to compare the performance of different coatings under identical machining conditions and to evaluate causes and phenomena of wear. TiN, (Ti,Al)N and Ti(C,N) coatings on high speed steel (HSS) show different performances in milling and turning of heat treated steel. The thermal and frictional properties of the coating materials affect the structure, the thickness and the flow of the chips, the contact area on the rake face and the tool life. Model tests show the influence of internal cooling and the thermal conductivity of coated HSS inserts. TiN and (Ti,Zr)N PVD coatings on cemented carbides were examined in interrupted turning and in milling of heat treated steel. Experimental results show a significant influence of typical time-temperature cycles of PVD and chemical vapor deposition (CVD) coating processes on the physical data and on the performance of the substrates. PVD coatings increase tool life, especially towards lower cutting speeds into ranges which cannot be applied with CVD coatings. The reason for this is the superior toughness of the PVD coated carbide. The combination of tough, micrograin carbide and PVD coating even enables broaching of case hardened sliding gears at a cutting speed of 66 m min -1 . (orig.)

  10. Process-Structure-Property Relationships of Micron Thick Gadolinium Oxide Films Deposited by Reactive Electron Beam-Physical Vapor Deposition (EB-PVD)

    Science.gov (United States)

    2014-12-01

    group C2/m). The oxygen and gadolinium coordination for each phase is shown next to the unit cells . Red corresponds to oxygen atoms and gray...light). The light photon is subsequently converted to an electron ( photoelectric effect), which undergoes multiplication (photo- electrons) to...atoms per unit cell . The resulting coordination is six for gadolinium and four for oxygen. The monoclinic Gd2Ü3 structure shown in Figure 2.3b, space

  11. Chemically vapor deposited coatings for multibarrier containment of nuclear wastes

    International Nuclear Information System (INIS)

    Rusin, J.M.; Shade, J.W.; Kidd, R.W.; Browning, M.F.

    1981-01-01

    Chemical vapor deposition (CVD) was selected as a feasible method to coat ceramic cores, since the technology has previously been demonstrated for high-temperature gas-cooled reactor (HTGR) fuel particles. CVD coatings, including SiC, PyC (pyrolytic carbon), SiO 2 , and Al 2 O 3 were studied. This paper will discuss the development and characterization of PyC and Al 2 O 3 CVD coatings on supercalcine cores. Coatings were applied to 2 mm particles in either fluidized or vibrating beds. The PyC coating was deposited in a fluidized bed with ZrO 2 diluent from C 2 H 2 at temperatures between 1100 and 1200 0 C. The Al 2 O 3 coatings were deposited in a vibrated bed by a two-stage process to minimize loss of PyC during the overcoating operation. This process involved applying 10 μm of Al 2 O 3 using water vapor hydrolysis of AlCl 3 and then switching to the more surface-controlled hydrolysis via the H 2 + CO 2 reaction (3CO 2 + 3H 2 + 2AlCl 3 = Al 2 O 3 + 6HCl + 3CO). Typically, 50 to 80 μm Al 2 O 3 coatings were applied over 30 to 40 μm PyC coatings. The coatings were evaluated by metallographic examination, PyC oxidation tests, and leach resistance. After air oxidation for 100 hours at 750 0 C, the duplex PyC/Al 2 O 3 coated particles exhibited a weight loss of 0.01 percent. Leach resistance is being determined for temperatures from 50 to 150 0 C in various solutions. Typical results are given for selected ions. The leach resistance of supercalcine cores is significantly improved by the application of PyC and/or Al 2 O 3 coatings

  12. Scaling behavior of columnar structure during physical vapor deposition

    Science.gov (United States)

    Meese, W. J.; Lu, T.-M.

    2018-02-01

    The statistical effects of different conditions in physical vapor deposition, such as sputter deposition, have on thin film morphology has long been the subject of interest. One notable effect is that of column development due to differential chamber pressure in the well-known empirical model called the Thornton's Structure Zone Model. The model is qualitative in nature and theoretical understanding with quantitative predictions of the morphology is still lacking due, in part, to the absence of a quantitative description of the incident flux distribution on the growth front. In this work, we propose an incident Gaussian flux model developed from a series of binary hard-sphere collisions and simulate its effects using Monte Carlo methods and a solid-on-solid growth scheme. We also propose an approximate cosine-power distribution for faster Monte Carlo sampling. With this model, it is observed that higher chamber pressures widen the average deposition angle, and similarly increase the growth of column diameters (or lateral correlation length) and the column-to-column separation (film surface wavelength). We treat both the column diameter and the surface wavelength as power laws. It is seen that both the column diameter exponent and the wavelength exponent are very sensitive to changes in pressure for low pressures (0.13 Pa to 0.80 Pa); meanwhile, both exponents saturate for higher pressures (0.80 Pa to 6.7 Pa) around a value of 0.6. These predictions will serve as guides to future experiments for quantitative description of the film morphology under a wide range of vapor pressure.

  13. Oxygen Barrier Coating Deposited by Novel Plasma-enhanced Chemical Vapor Deposition

    DEFF Research Database (Denmark)

    Jiang, Juan; Benter, M.; Taboryski, Rafael Jozef

    2010-01-01

    We report the use of a novel plasma-enhanced chemical vapor deposition chamber with coaxial electrode geometry for the SiOx deposition. This novel plasma setup exploits the diffusion of electrons through the inner most electrode to the interior samples space as the major energy source. This confi......We report the use of a novel plasma-enhanced chemical vapor deposition chamber with coaxial electrode geometry for the SiOx deposition. This novel plasma setup exploits the diffusion of electrons through the inner most electrode to the interior samples space as the major energy source....... This configuration enables a gentle treatment of sensitive materials like low-density polyethylene foils and biodegradable materials. SiOx coatings deposited in the novel setup were compared with other state of the art plasma coatings and were found to possess equally good or better barrier properties. The barrier...... effect of single-layer coatings deposited under different reaction conditions was studied. The coating thickness and the carbon content in the coatings were found to be the critical parameters for the barrier property. The novel barrier coating was applied on different polymeric materials...

  14. Low temperature deposition of crystalline silicon on glass by hot wire chemical vapor deposition

    Science.gov (United States)

    Chung, Yung-Bin; Park, Hyung-Ki; Lee, Dong-Kwon; Jo, Wook; Song, Jean-Ho; Lee, Sang-Hoon; Hwang, Nong-Moon

    2011-07-01

    Although the deposition of crystalline silicon on a glass substrate has been pursued using hot wire chemical vapor deposition or plasma enhanced chemical vapor deposition for applications in flat panel displays and solar cells, the process has been only partly successful because of the inevitable formation of an amorphous incubation layer on a glass substrate. Currently, the crystalline silicon films are prepared by depositing an amorphous silicon film on a glass substrate and then crystallizing it by excimer laser annealing (ELA), metal induced crystallization or rapid thermal annealing (RTA). Here we report a new process, which can remove the amorphous incubation layer and thereby deposit crystalline silicon directly on glass using HCl. The intrinsic crystalline silicon film has a conductivity of 3.7×10 -5 Scm -1 and the n-type doped crystalline silicon film has the Hall mobility of 15.8 cm 2V -1 s -1, whose values are comparable to those prepared by ELA and RTA, respectively.

  15. Anisotropic Friction of Wrinkled Graphene Grown by Chemical Vapor Deposition.

    Science.gov (United States)

    Long, Fei; Yasaei, Poya; Yao, Wentao; Salehi-Khojin, Amin; Shahbazian-Yassar, Reza

    2017-06-21

    Wrinkle structures are commonly seen on graphene grown by the chemical vapor deposition (CVD) method due to the different thermal expansion coefficient between graphene and its substrate. Despite the intensive investigations focusing on the electrical properties, the nanotribological properties of wrinkles and the influence of wrinkle structures on the wrinkle-free graphene remain less understood. Here, we report the observation of anisotropic nanoscale frictional characteristics depending on the orientation of wrinkles in CVD-grown graphene. Using friction force microscopy, we found that the coefficient of friction perpendicular to the wrinkle direction was ∼194% compare to that of the parallel direction. Our systematic investigation shows that the ripples and "puckering" mechanism, which dominates the friction of exfoliated graphene, plays even a more significant role in the friction of wrinkled graphene grown by CVD. The anisotropic friction of wrinkled graphene suggests a new way to tune the graphene friction property by nano/microstructure engineering such as introducing wrinkles.

  16. Tribological Properties of Chemical Vapor Deposited Graphene Coating Layer

    International Nuclear Information System (INIS)

    Lee, Jong Hoon; Kim, Sun Hye; Cho, Doo Ho; Kim, Se Chang; Baek, Seung Guk; Lee, Jong Gu; Choi, Jae-Boong; Seok, Chang Sung; Kim, Moon Ki; Koo, Ja Choon; Lim, Byeong Soo; Kang, Junmo

    2012-01-01

    Graphene has recently received high attention as a promising material for various applications, and many related studies have been undertaken to reveal its basic mechanical properties. However, the tribological properties of graphene film fabricated by the chemical vapor deposition (CVD) method are barely known. In this study, the contact angle and frictional wear characteristics of graphene coated copper film were investigated under room temperature, normal air pressure, and no lubrication condition. The contact angle was measured by sessile drop method and the wear test was carried out under normal loads of 660 mN and 2940 mN, respectively. The tribological behaviors of a graphene coating layer were also examined. Compared to heat treated bare copper foil, the graphene coated one shows a higher contact angle and lower friction coefficient.

  17. Tribological Properties of Chemical Vapor Deposited Graphene Coating Layer

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong Hoon; Kim, Sun Hye; Cho, Doo Ho; Kim, Se Chang; Baek, Seung Guk; Lee, Jong Gu; Choi, Jae-Boong; Seok, Chang Sung; Kim, Moon Ki; Koo, Ja Choon; Lim, Byeong Soo [Sungkyunkwan University, Suwon (Korea, Republic of); Kang, Junmo [Sungkyunkwan University, Suwon (Korea, Republic of)

    2012-03-15

    Graphene has recently received high attention as a promising material for various applications, and many related studies have been undertaken to reveal its basic mechanical properties. However, the tribological properties of graphene film fabricated by the chemical vapor deposition (CVD) method are barely known. In this study, the contact angle and frictional wear characteristics of graphene coated copper film were investigated under room temperature, normal air pressure, and no lubrication condition. The contact angle was measured by sessile drop method and the wear test was carried out under normal loads of 660 mN and 2940 mN, respectively. The tribological behaviors of a graphene coating layer were also examined. Compared to heat treated bare copper foil, the graphene coated one shows a higher contact angle and lower friction coefficient.

  18. Study of Polymer Crystallization by Physical Vapor Deposition

    Science.gov (United States)

    Jeong, Hyuncheol

    When a polymer is confined under the submicron length scale, confinement size and interfaces can significantly impact the crystallization kinetics and resulting morphology. The ability to tune the morphology of confined polymer systems is of critical importance for the development of high-performance polymer microelectronics. The wisdom from the research on confined crystallization suggests that it would be beneficial to have a processing route in which the crystallization of polymers is driven by interface and temperature effects at a nanometer-scale confinement. In practice, for atomic and small-molecular systems, physical vapor deposition (PVD) has been recognized as the most successful processing route for the precise control of the film structure at surface utilizing confinement effects. While standard PVD technologies are not generally applicable to the deposition of the chemically fragile macromolecules, the development of matrix-assisted pulsed laser evaporation (MAPLE) now enables the non-destructive PVD of high-molecular weight polymers. In this thesis work, we investigated the use of MAPLE for the precise control of the crystallization of polymer films at a molecular level. We also sought to decipher the rules governing the crystallization of confined polymers, by using MAPLE as a tool to form confined polymer systems onto substrates with a controlled temperature. We first explored the early stages of film growth and crystallization of poly(ethylene oxide) (PEO) at the substrate surface formed by MAPLE. The unique mechanism of film formation in MAPLE, the deposition of submicron-sized polymer droplets, allowed for the manifestation of confinement and substrate effects in the crystallization of MAPLE-deposited PEO. Furthermore, we also focused on the property of the amorphous PEO film formed by MAPLE, showing the dependence of polymer crystallization kinetics on the thermal history of the amorphous phase. Lastly, we probed how MAPLE processing affected

  19. 2017 Report for New LANL Physical Vapor Deposition Capability

    Energy Technology Data Exchange (ETDEWEB)

    Roman, Audrey Rae [Los Alamos National Laboratory; Zhao, Xinxin [Los Alamos National Laboratory; Bond, Evelyn M. [Los Alamos National Laboratory; Gooden, Matthew Edgell [Los Alamos National Laboratory; Rundberg, Robert S. [Los Alamos National Laboratory; Bredeweg, Todd Allen [Los Alamos National Laboratory

    2017-10-03

    There is an urgent need at LANL to achieve uniform, thin film actinide targets that are essential for nuclear physics experiments. The target preparation work is currently performed externally by Professor Walter Loveland at Oregon State University, who has made various evaporated actinide targets such as Th and U for use on several nuclear physics measurements at LANSCE. We are developing a vapor deposition capability, with the goal of evaporating Th and U in the Actinide Research Facility (ARF) at TA-48. In the future we plan to expand this work to evaporating transuranic elements, such as Pu. The ARF is the optimal location for evaporating actinides because this lab is specifically dedicated to actinide research. There are numerous instruments in the ARF that can be used to provide detailed characterization of the evaporated thin films such as: Table top Scanning Electron Microscope, In-situ X-Ray Diffraction, and 3D Raman spectroscopy. These techniques have the ability to determine the uniformity, surface characterization, and composition of the deposits.

  20. Plasma and Ion Assistance in Physical Vapor Deposition: AHistorical Perspective

    Energy Technology Data Exchange (ETDEWEB)

    Anders, Andre

    2007-02-28

    Deposition of films using plasma or plasma-assist can betraced back surprisingly far, namely to the 18th century for arcs and tothe 19th century for sputtering. However, only since the 1960s thecoatings community considered other processes than evaporation for largescale commercial use. Ion Plating was perhaps the first importantprocess, introducing vapor ionization and substrate bias to generate abeam of ions arriving on the surface of the growing film. Ratherindependently, cathodic arc deposition was established as an energeticcondensation process, first in the former Soviet Union in the 1970s, andin the 1980s in the Western Hemisphere. About a dozen various ion-basedcoating technologies evolved in the last decades, all characterized byspecific plasma or ion generation processes. Gridded and gridless ionsources were taken from space propulsion and applied to thin filmdeposition. Modeling and simulation have helped to make plasma and ionseffects to be reasonably well understood. Yet--due to the complex, oftennon-linear and non-equilibrium nature of plasma and surfaceinteractions--there is still a place for the experience plasma"sourcerer."

  1. Deposition and characterization of Ru thin films prepared by metallorganic chemical vapor deposition

    CERN Document Server

    Kang, S Y; Lee, S K; Hwang, C S; Kim, H J

    2000-01-01

    Ru thin films were deposited at 300 approx 400 .deg. C by using Ru(C sub 5 H sub 4 C sub 2 H sub 5) sub 2 (Ru(EtCp) sub 2) as a precursor and low-pressure metalorganic chemical vapor deposition. The addition of O sub 2 gas was essential to form Ru thin films. The deposition rates of the films were about 200 A/min. For low oxygen addition and high substrate temperature, RuO sub 2 phases were formed. Also, thermodynamic calculations showed that all the supplied oxygen was consumed to oxidize carbon and hydrogen, cracked from the precursor ligand, rather than Ru. Thus, metal films could be obtained There was an optimum oxygen to precursor ratio at which the pure Ru phase could be obtained with minimum generation of carbon and RuO sub 2

  2. An analytical kinetic model for chemical-vapor deposition of pureB layers from diborane

    NARCIS (Netherlands)

    Mohammadi, V.; De Boer, W.B.; Nanver, L.K.

    2012-01-01

    In this paper, an analytical model is established to describe the deposition kinetics and the deposition chamber characteristics that determine the deposition rates of pure boron (PureB-) layers grown by chemical-vapor deposition (CVD) from diborane (B2H6) as gas source on a non-rotating silicon

  3. Pattern Dependency and Loading Effect of Pure-Boron-Layer Chemical-Vapor Deposition

    NARCIS (Netherlands)

    Mohammadi, V.; De Boer, W.B.; Scholtes, T.L.M.; Nanver, L.K.

    2012-01-01

    The pattern dependency of pure-boron (PureB) layer chemical-vapor Deposition (CVD) is studied with respect to the correlation between the deposition rate and features like loading effects, deposition parameters and deposition window sizes. It is shown experimentally that the oxide coverage ratio and

  4. An introduction to beam physics

    CERN Document Server

    Berz, Martin; Wan, Weishi

    2015-01-01

    The field of beam physics touches many areas of physics, engineering, and the sciences. In general terms, beams describe ensembles of particles with initial conditions similar enough to be treated together as a group so that the motion is a weakly nonlinear perturbation of a chosen reference particle. Particle beams are used in a variety of areas, ranging from electron microscopes, particle spectrometers, medical radiation facilities, powerful light sources, and astrophysics to large synchrotrons and storage rings such as the LHC at CERN. An Introduction to Beam Physics is based on lectures given at Michigan State University’s Department of Physics and Astronomy, the online VUBeam program, the U.S. Particle Accelerator School, the CERN Academic Training Programme, and various other venues. It is accessible to beginning graduate and upper-division undergraduate students in physics, mathematics, and engineering. The book begins with a historical overview of methods for generating and accelerating beams, high...

  5. High Temperature Multilayer Environmental Barrier Coatings Deposited Via Plasma Spray-Physical Vapor Deposition

    Science.gov (United States)

    Harder, Bryan James; Zhu, Dongming; Schmitt, Michael P.; Wolfe, Douglas E.

    2014-01-01

    Si-based ceramic matrix composites (CMCs) require environmental barrier coatings (EBCs) in combustion environments to avoid rapid material loss. Candidate EBC materials have use temperatures only marginally above current technology, but the addition of a columnar oxide topcoat can substantially increase the durability. Plasma Spray-Physical Vapor Deposition (PS-PVD) allows application of these multilayer EBCs in a single process. The PS-PVD technique is a unique method that combines conventional thermal spray and vapor phase methods, allowing for tailoring of thin, dense layers or columnar microstructures by varying deposition conditions. Multilayer coatings were deposited on CMC specimens and assessed for durability under high heat flux and load. Coated samples with surface temperatures ranging from 2400-2700F and 10 ksi loads using the high heat flux laser rigs at NASA Glenn. Coating morphology was characterized in the as-sprayed condition and after thermomechanical loading using electron microscopy and the phase structure was tracked using X-ray diffraction.

  6. Synthesis and characterization of diamond microcrystals and nanorods deposited by hot cathode direct current plasma chemical vapor deposition method

    NARCIS (Netherlands)

    Zeng, L.; Peng, H.; Wang, W.; Chen, Y.; Lei, D.; Qi, W.; Liang, J.; Zhao, J.; Kong, X.; Zhang, H.

    2008-01-01

    (111) diamond microcrystals and (100) diamond microcrystals and nanorods were synthesized on Si substrate by hot cathode direct current plasma chemical vapor deposition method. The morphology, structure, and optical properties of the diamond films were characterized by scanning electron microscopy,

  7. Chemical vapor deposited silica coatings for solar mirror protection

    Science.gov (United States)

    Gulino, Daniel A.; Dever, Therese M.; Banholzer, William F.

    1988-01-01

    A variety of techniques is available to apply protective coatings to oxidation susceptible spacecraft components, and each has associated advantages and disadvantages. Film applications by means of chemical vapor deposition (CVD) has the advantage of being able to be applied conformally to objects of irregular shape. For this reason, a study was made of the oxygen plasma durability of thin film (less than 5000 A) silicon dioxide coatings applied by CVD. In these experiments, such coatings were applied to silver mirrors, which are strongly subject to oxidation, and which are proposed for use on the space station solar dynamic power system. Results indicate that such coatings can provide adequate protection without affecting the reflectance of the mirror. Scanning electron micrographs indicated that oxidation of the silver layer did occur at stress crack locations, but this did not affect the measured solar reflectances. Oxidation of the silver did not proceed beyond the immediate location of the crack. Such stress cracks did not occur in thinner silica films, and hence such films would be desirable for this application.

  8. Development of microforming process combined with selective chemical vapor deposition

    Directory of Open Access Journals (Sweden)

    Koshimizu Kazushi

    2015-01-01

    Full Text Available Microforming has been received much attention in the recent decades due to the wide use of microparts in electronics and medical purpose. For the further functionalization of these micro devices, high functional surface with noble metals and nanomaterials are strongly required in bio- and medical fields, such as bio-sensors. To realize the efficient manufacturing process, which can deform the submillimeter scale bulk structure and can construct the micro to nanometer scale structures in one process, the present study proposes a combined process of microforming for metal foils with a selective chemical vapor deposition (SCVD on the active surface of work materials. To clarify the availability of this proposed process, the feasibility of SCVD of functional materials to active surface of titanium (Ti was investigated. CVD of iron (Fe and carbon nanotubes (CNTs which construct CNTs on the patterned surface of active Ti and non-active oxidation layer were conducted. Ti thin films on silicon substrate and Fe were used as work materials and functional materials, respectively. CNTs were grown on only Ti surface. Consequently, the selectivity of the active surface of Ti to the synthesis of Fe particles in CVD process was confirmed.

  9. Residual metallic contamination of transferred chemical vapor deposited graphene.

    Science.gov (United States)

    Lupina, Grzegorz; Kitzmann, Julia; Costina, Ioan; Lukosius, Mindaugas; Wenger, Christian; Wolff, Andre; Vaziri, Sam; Östling, Mikael; Pasternak, Iwona; Krajewska, Aleksandra; Strupinski, Wlodek; Kataria, Satender; Gahoi, Amit; Lemme, Max C; Ruhl, Guenther; Zoth, Guenther; Luxenhofer, Oliver; Mehr, Wolfgang

    2015-05-26

    Integration of graphene with Si microelectronics is very appealing by offering a potentially broad range of new functionalities. New materials to be integrated with the Si platform must conform to stringent purity standards. Here, we investigate graphene layers grown on copper foils by chemical vapor deposition and transferred to silicon wafers by wet etching and electrochemical delamination methods with respect to residual submonolayer metallic contaminations. Regardless of the transfer method and associated cleaning scheme, time-of-flight secondary ion mass spectrometry and total reflection X-ray fluorescence measurements indicate that the graphene sheets are contaminated with residual metals (copper, iron) with a concentration exceeding 10(13) atoms/cm(2). These metal impurities appear to be partially mobile upon thermal treatment, as shown by depth profiling and reduction of the minority charge carrier diffusion length in the silicon substrate. As residual metallic impurities can significantly alter electronic and electrochemical properties of graphene and can severely impede the process of integration with silicon microelectronics, these results reveal that further progress in synthesis, handling, and cleaning of graphene is required to advance electronic and optoelectronic applications.

  10. Growth of graphene underlayers by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Fabiane, Mopeli; Khamlich, Saleh; Bello, Abdulhakeem; Dangbegnon, Julien; Momodu, Damilola; Manyala, Ncholu, E-mail: ncholu.manyala@up.ac.za [Department of Physics, Institute of Applied Materials, SARChI Chair in Carbon Technology and Materials, University of Pretoria, Pretoria 0028 (South Africa); Charlie Johnson, A. T. [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)

    2013-11-15

    We present a simple and very convincing approach to visualizing that subsequent layers of graphene grow between the existing monolayer graphene and the copper catalyst in chemical vapor deposition (CVD). Graphene samples were grown by CVD and then transferred onto glass substrates by the bubbling method in two ways, either direct-transfer (DT) to yield poly (methyl methacrylate) (PMMA)/graphene/glass or (2) inverted transfer (IT) to yield graphene/PMMA/glass. Field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM) were used to reveal surface features for both the DT and IT samples. The results from FE-SEM and AFM topographic analyses of the surfaces revealed the underlayer growth of subsequent layers. The subsequent layers in the IT samples are visualized as 3D structures, where the smaller graphene layers lie above the larger layers stacked in a concentric manner. The results support the formation of the so-called “inverted wedding cake” stacking in multilayer graphene growth.

  11. Rapid thermal metalorganic chemical vapor deposition of II VI compounds

    Science.gov (United States)

    Stolyarova, S.; Amir, N.; Nemirovsky, Y.

    1998-02-01

    In this paper we analyze the potential benefits of rapid thermal processing combined with metalorganic chemical vapor deposition (RT-MOCVD) for II-VI compounds and review our first results of the application of RT-MOCVD to the growth of CdTe/CdZnTe, CdTe/HgCdTe and ZnTe/CdTe heterostructures. The RT-MOCVD growth of (1 1 1) CdTe and ZnTe was performed in the A.G. Associates Heatpulse CVD-800™ system using a horizontal quartz reactor heated from both sides by tungsten-halogen lamps. The main features of RT-MOCVD of II-VI materials are: very high growth rates (up to 60 μm/h for CdTe and 30 μm/h for ZnTe); low point defect densities in the epilayers; more abrupt interfaces and less substrate surface degradation compared to conventional MOCVD. Potential of RT-MOCVD for MCT passivation has been shown.

  12. Comparative study of tantalum deposition by chemical vapor deposition and electron beam vacuum evaporation

    International Nuclear Information System (INIS)

    Spitz, J.; Chevallier, J.

    1975-01-01

    The coating by tantalum of steel parts has been carried out by the two following methods: chemical vapor deposition by hydrogen reduction of TaCl 5 (temperature=1100 deg C, pressure=200 mmHg, H 2 /TaCl 5 =10); electron beam vacuum evaporation. In this case Ta was firstly condensed by ion plating (P(Ar)=5x10 -3 up to 2x10 -2 mmHg; U(c)=3 to -4kV and J(c)=0.2 to 1mAcm -2 ) in order to ensure a good adhesion between deposit and substrate; then by vacuum condensation (substrate temperature: 300 to 650 deg C) to ensure that the coating is impervious to HCl an H 2 SO 4 acids. The advantages and inconveniences of each method are discussed [fr

  13. Diamond-like carbon films deposited on polycarbonates by plasma-enhanced chemical vapor deposition

    International Nuclear Information System (INIS)

    Guo, C.T.

    2008-01-01

    Diamond-like carbon films were coated on optical polycarbonate using plasma-enhanced chemical vapor deposition. A mixture of SiH 4 and CH 4 /H 2 gases was utilized to reduce the internal compressive stress of the deposited films. The structure of the DLC films was characterized as a function of film thickness using Raman spectroscopy. The dependence of G peak positions and the intensity ratio of I D /I G on the DLC film thicknesses was analyzed in detail. Other studies involving atomic force microscopy, ultraviolet visible spectrometry, and three adhesion tests were conducted. Good transparency in the visible region, and good adhesion between diamond-like carbon films and polycarbonate were demonstrated. One-time recordings before and after a DLC film was coated on compact rewritable disc substrates were analyzed as a case study. The results reveal that the diamond-like carbon film overcoating the optical polycarbonates effectively protects the storage media

  14. Instrumentation for Colliding Beam Physics

    CERN Document Server

    2017-01-01

    INSTR17, the International Conference on Instrumentation for Colliding Beam Physics, will be held in the Budker Institute of Nuclear Physics, Novosibirsk, Russia, on 27 February – 4 March, 2017. The conference covers novel methods of particle detection used in various experiments at particle accelerators as well as in astrophysics. It is organized in close relationship with the Vienna Conference on Instrumentation (last held in 2016) and the Pisa Meeting on Advanced Detectors (last held in 2015). The deadline for registration and abstract submission is 15 January. For more details visit the conference website instr17.inp.nsk.su. Will be published in: JINST

  15. Chemical Vapor-Deposited (CVD) Diamond Films for Electronic Applications

    Science.gov (United States)

    1995-01-01

    Diamond films have a variety of useful applications as electron emitters in devices such as magnetrons, electron multipliers, displays, and sensors. Secondary electron emission is the effect in which electrons are emitted from the near surface of a material because of energetic incident electrons. The total secondary yield coefficient, which is the ratio of the number of secondary electrons to the number of incident electrons, generally ranges from 2 to 4 for most materials used in such applications. It was discovered recently at the NASA Lewis Research Center that chemical vapor-deposited (CVD) diamond films have very high secondary electron yields, particularly when they are coated with thin layers of CsI. For CsI-coated diamond films, the total secondary yield coefficient can exceed 60. In addition, diamond films exhibit field emission at fields orders of magnitude lower than for existing state-of-the-art emitters. Present state-of-the-art microfabricated field emitters generally require applied fields above 5x10^7 V/cm. Research on field emission from CVD diamond and high-pressure, high-temperature diamond has shown that field emission can be obtained at fields as low as 2x10^4 V/cm. It has also been shown that thin layers of metals, such as gold, and of alkali halides, such as CsI, can significantly increase field emission and stability. Emitters with nanometer-scale lithography will be able to obtain high-current densities with voltages on the order of only 10 to 15 V.

  16. Single crystal diamond detectors grown by chemical vapor deposition

    International Nuclear Information System (INIS)

    Tuve, C.; Angelone, M.; Bellini, V.; Balducci, A.; Donato, M.G.; Faggio, G.; Marinelli, M.; Messina, G.; Milani, E.; Morgada, M.E.; Pillon, M.; Potenza, R.; Pucella, G.; Russo, G.; Santangelo, S.; Scoccia, M.; Sutera, C.; Tucciarone, A.; Verona-Rinati, G.

    2007-01-01

    The detection properties of heteropitaxial (polycrystalline, pCVD) and homoepitaxial (single crystal, scCVD) diamond films grown by microwave chemical vapor deposition (CVD) in the Laboratories of Roma 'Tor Vergata' University are reported. The pCVD diamond detectors were tested with α-particles from different sources and 12 C ions produced by 15MV Tandem accelerator at Southern National Laboratories (LNS) in Catania (Italy). pCVDs were also used to monitor 14MeV neutrons produced by the D-T plasma at Joint European Torus (JET), Culham, U.K. The limit of pCVDs is the poor energy resolution. To overcome this problem, we developed scCVD diamonds using the same reactor parameters that optimized pCVD diamonds. scCVD were grown on a low cost (100) HPHT single crystal substrate. A detector 110μm thick was tested under α-particles and under 14MeV neutron irradiation. The charge collection efficiency spectrum measured under irradiation with a triple α-particle source shows three clearly resolved peaks, with an energy resolution of about 1.1%. The measured spectra under neutron irradiation show a well separated C(n,α 0 ) 9 Be12 reaction peak with an energy spread of 0.5MeV for 14.8MeV neutrons and 0.3MeV for 14.1MeV neutrons, which are fully compatible with the energy spread of the incident neutron beams

  17. Deposition characteristics of titanium coating deposited on SiC fiber by cold-wall chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Xian, E-mail: luo_shenfan@hotmail.com; Wu, Shuai; Yang, Yan-qing; Jin, Na; Liu, Shuai; Huang, Bin

    2016-12-01

    The deposition characteristics of titanium coating on SiC fiber using TiCl{sub 4}-H{sub 2}-Ar gas mixture in a cold-wall chemical vapor deposition were studied by the combination of thermodynamic analysis and experimental studies. The thermodynamic analysis of the reactions in the TiCl{sub 4}-H{sub 2}-Ar system indicates that TiCl{sub 4} transforms to titanium as the following paths: TiCl{sub 4} → TiCl{sub 3} → Ti, or TiCl{sub 4} → TiCl{sub 3} → TiCl{sub 2} → Ti. The experimental results show that typical deposited coating contains two distinct layers: a TiC reaction layer close to SiC fiber and titanium coating which has an atomic percentage of titanium more than 70% and that of carbon lower than 30%. The results illustrate that a carbon diffusion barrier coating needs to be deposited if pure titanium is to be prepared. The deposition rate increases with the increase of temperature, but higher temperature has a negative effect on the surface uniformity of titanium coating. In addition, appropriate argon gas flow rate has a positive effect on smoothing the surface morphology of the coating. - Highlights: • Both thermodynamic analysis and experimental studies were adopted in this work. • The transformation paths of TiCl{sub 4} to Ti is: TiCl{sub 4} → TiCl{sub 3} → Ti, or TiCl{sub 4} → TiCl{sub 3} → TiCl{sub 2} → Ti. • Typical deposited Ti coating on SiC fiber contained two distinct layers. • Deposition temperature is important on deposition rate and morphologies. • Appropriate argon gas flow rate has a positive effect on smoothing of the coating.

  18. Dynamic scaling and kinetic roughening of poly(ethylene) islands grown by vapor phase deposition

    Czech Academy of Sciences Publication Activity Database

    Choukourov, A.; Melnichuk, I.; Gordeev, I.; Kylián, O.; Hanuš, J.; Kousal, J.; Solař, P.; Hanyková, L.; Brus, Jiří; Slavínská, D.; Biederman, H.

    2014-01-01

    Roč. 565, 28 August (2014), s. 249-260 ISSN 0040-6090 Institutional support: RVO:61389013 Keywords : poly(ethylene) * physical vapor deposition * island growth Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.759, year: 2014

  19. Modeling chemical vapor deposition of silicon dioxide in microreactors at atmospheric pressure

    NARCIS (Netherlands)

    Konakov, S.A.; Krzhizhanovskaya, V.V.

    2015-01-01

    We developed a multiphysics mathematical model for simulation of silicon dioxide Chemical Vapor Deposition (CVD) from tetraethyl orthosilicate (TEOS) and oxygen mixture in a microreactor at atmospheric pressure. Microfluidics is a promising technology with numerous applications in chemical synthesis

  20. A Mini-Prototype YBCO SMES Using Combustion Chemical Vapor Deposition Technique

    National Research Council Canada - National Science Library

    Shoup, Shara

    2000-01-01

    .... Textured nickel metal substrates were joined by 1 mm joints by several methods and in several physical configurations and then tested for feasibility by using the Combustion Chemical Vapor Deposition (CCVD...

  1. Amorphous Carbon Deposited by a Novel Aerosol-Assisted Chemical Vapor Deposition for Photovoltaic Solar Cells

    Science.gov (United States)

    Ahmad, Nurfadzilah; Kamaruzzaman, Dayana; Rusop, Mohamad

    2012-06-01

    Amorphous carbon (a-C) solar cells were successfully prepared using a novel and self-designed aerosol-assisted chemical vapor deposition (AACVD) method using camphor oil as a precursor. The fabricated solar cell with the configuration of Au/p-C/n-Si/Au achieved an efficiency of 0.008% with a fill factor of 0.15 for the device deposited at 0.5 h. The current-voltage (I-V) graph emphasized on the linear graph (ohmic) for the a-C thin films, whereas for the p-n device structure, a rectifying curve was obtained. The rectifying curves signify the heterojunction between the p-type a-C film and the n-Si substrate and designate the generation of electron-hole pair of the samples under illumination. Photoresponse characteristics of the deposited a-C was highlighted when being illuminated (AM 1.5 illumination: 100 mW/cm2, 25 °C). Transmittance spectrum exhibit a large transmittance value (>85%) and absorption coefficient value of 103-104 cm-1 at the visible range of 390 to 790 nm. The atomization of a liquid precursor solution into fine sub-micrometre-sized aerosol droplets in AACVD induced the smooth surface of a-C films. To the best of our knowledge, fabrication of a-C solar cell using this AACVD method has not yet been reported.

  2. Selective WSi2 Schottky diodes made by rapid thermal chemical vapor deposition of WCl6

    Science.gov (United States)

    Trincat, F.; Regolini, J. L.; Mercier, J.; Bensahel, D.

    1991-12-01

    Selective WSi2/Si Schottky diodes, with an ideality factor of 1.02, are obtained by limited reaction processing chemical vapor deposition at 800 °C, using WCl6 vapor diluted in H2. The deposition temperature is shown to be the most important parameter for defect formation. The diodes were fabricated on patterned and blanket wafers, and no additional thermal treatment is needed to obtain the final diode characteristics.

  3. Preparation of membranes using solvent-less vapor deposition followed by in-situ polymerization

    Energy Technology Data Exchange (ETDEWEB)

    O' Brien, Kevin C [San Ramon, CA; Letts, Stephan A [San Ramon, CA; Spadaccini, Christopher M [Oakland, CA; Morse, Jeffrey C [Pleasant Hill, CA; Buckley, Steven R [Modesto, CA; Fischer, Larry E [Los Gatos, CA; Wilson, Keith B [San Ramon, CA

    2012-01-24

    A system of fabricating a composite membrane from a membrane substrate using solvent-less vapor deposition followed by in-situ polymerization. A first monomer and a second monomer are directed into a mixing chamber in a deposition chamber. The first monomer and the second monomer are mixed in the mixing chamber providing a mixed first monomer and second monomer. The mixed first monomer and second monomer are solvent-less vapor deposited onto the membrane substrate in the deposition chamber. The membrane substrate and the mixed first monomer and second monomer are heated to produce in-situ polymerization and provide the composite membrane.

  4. Preparation of membranes using solvent-less vapor deposition followed by in-situ polymerization

    Science.gov (United States)

    O'Brien, Kevin C [San Ramon, CA; Letts, Stephan A [San Ramon, CA; Spadaccini, Christopher M [Oakland, CA; Morse, Jeffrey C [Pleasant Hill, CA; Buckley, Steven R [Modesto, CA; Fischer, Larry E [Los Gatos, CA; Wilson, Keith B [San Ramon, CA

    2010-07-13

    A system of fabricating a composite membrane from a membrane substrate using solvent-less vapor deposition followed by in-situ polymerization. A first monomer and a second monomer are directed into a mixing chamber in a deposition chamber. The first monomer and the second monomer are mixed in the mixing chamber providing a mixed first monomer and second monomer. The mixed first monomer and second monomer are solvent-less vapor deposited onto the membrane substrate in the deposition chamber. The membrane substrate and the mixed first monomer and second monomer are heated to produce in-situ polymerization and provide the composite membrane.

  5. Rapid synthesis of tantalum oxide dielectric films by microwave microwave-assisted atmospheric chemical vapor deposition

    International Nuclear Information System (INIS)

    Ndiege, Nicholas; Subramanian, Vaidyanathan; Shannon, Mark A.; Masel, Richard I.

    2008-01-01

    Microwave-assisted chemical vapor deposition has been used to generate high quality, high-k dielectric films on silicon at high deposition rates with film thicknesses varying from 50 nm to 110 μm using inexpensive equipment. Characterization of the post deposition products was performed by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Auger electron spectroscopy and Raman spectroscopy. Film growth was determined to occur via rapid formation and accumulation of tantalum oxide clusters from tantalum (v) ethoxide (Ta(OC 2 H 5 ) 5 ) vapor on the deposition surface

  6. Supramolecular structure of a perylene derivative in thin films deposited by physical vapor deposition

    International Nuclear Information System (INIS)

    Fernandes, Jose D.; Aoki, Pedro H.B.; Constantino, Carlos J.J.; Junior, Wagner D.M.; Teixeira, Silvio R.

    2014-01-01

    Full text: Thin films of a perylene derivative, the bis butylimido perylene (BuPTCD), were produced using thermal evaporation (PVD, physical vapor deposition). The main objective is to investigate the supramolecular structure of the BuPTCD in these PVD films, which implies to control the thickness and to determine the molecular organization, morphology at micro and nanometer scales and crystallinity. This supramolecular structure is a key factor in the optical and electrical properties of the film. The ultraviolet-visible absorption revealed an uniform growth of the PVD films. The optical and atomic force microscopy images showed a homogeneous surface of the film at micro and nanometer scales. A preferential orientation of the molecules in the PVD films was determined via infrared absorption. The X-ray diffraction showed that both powder and PVD film are in the crystalline form. (author)

  7. Center for Beam Physics, 1993

    International Nuclear Information System (INIS)

    1994-05-01

    The Center for Beam Physics is a multi-disciplinary research and development unit in the Accelerator and Fusion Research Division at Lawrence Berkeley Laboratory. At the heart of the Center's mission is the fundamental quest for mechanisms of acceleration, radiation and focusing of energy. Dedicated to exploring the frontiers of the physics of (and with) particle and photon beams, its primary mission is to promote the science and technology of the production, manipulation, storage and control systems of charged particles and photons. The Center serves this mission via conceptual studies, theoretical and experimental research, design and development, institutional project involvement, external collaborations, association with industry and technology transfer. This roster provides a glimpse at the scientists, engineers, technical support, students, and administrative staff that make up this team and a flavor of their multifaceted activities during 1993

  8. 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)

  9. Formation of amorphous metal alloys by chemical vapor deposition

    Science.gov (United States)

    Mullendore, Arthur W.

    1990-01-01

    Amorphous alloys are deposited by a process of thermal dissociation of mixtures or organometallic compounds and metalloid hydrides, e.g., transition metal carbonyl such as nickel carbonyl, and diborane. Various sizes and shapes of deposits can be achieved, including near-net-shape free standing articles, multilayer deposits, and the like. Manipulation or absence of a magnetic field affects the nature and the structure of the deposit.

  10. Effects of hot isostatic pressure on titanium nitride films deposited by physical vapor deposition

    Directory of Open Access Journals (Sweden)

    Carbonari M.J.

    2001-01-01

    Full Text Available Films of titanium nitride deposited by physical vapor deposition on 304 L stainless steel substrates were hot isostatic pressed (HIP under 150 MPa at 550 °C. To study the effects of this treatment on the microstructure of those films, X-ray diffraction analyses, Rutherford Backscattering spectroscopy, scanning electron microscopy, and atomic force microscopy were performed. Surface hardness, and roughness were also evaluated to characterize the TiN properties. The hot isostatic pressure leads to an increase of hardness for depths up to 0.1 mum and a crystallographic texture change from (111 to (200. The original TiN golden color turned to red after the treatment. An increase of the grain size has been observed for hot isostatic pressed samples, but the stoichiometry of the TiN film was determined to be 1:1 by RBS. The microstructure observed by atomic force microscopy indicated that the TiN film surface is smoother after the HIP treatment.

  11. Electron emission from nano-structured carbon films fabricated by hot-filament chemical-vapor deposition and microwave plasma-enhanced chemical vapor deposition

    CERN Document Server

    Park, K H; Lee, K M; Oh, S G; Lee, S I; Koh, K H

    2000-01-01

    The electron-emission characteristics of nano-structured carbon films fabricated by using the HFCVD (hot- filament chemical-vapor deposition) and the MPECVD (microwave plasma-enhanced chemical-vapor deposition) methods with a metal catalyst are presented. According to our observation, neither the formation nor the alignment of nano tubes is absolutely necessary to realize carbon-based electron emitters. However, utilization of chrome as an interlayer between Si substrates and metal catalyst particles results in a great improvement in the emission characteristics and the mechanical stability. Also, fabrication of good electron-emitting carbon films on glass substrates, with sputter-deposited chrome electrodes,at a nominal temperature approx 615 .deg. C was demonstrated.

  12. Optimization of plasma-enhanced chemical vapor deposition silicon oxynitride layers for integrated optics applications

    NARCIS (Netherlands)

    Hussein, M.G.; Worhoff, Kerstin; Sengo, G.; Sengo, G.; Driessen, A.

    2007-01-01

    Silicon oxynitride $(SiO_{x}N_{y}:H)$ layers were grown from 2% $SiH_{4}/N_{2}$ and $N_{2}O$ gas mixtures by plasma-enhanced chemical vapor deposition (PECVD). Layer properties such as refractive index, deposition rate, thickness non-uniformity and hydrogen bond content were correlated to the

  13. Plasma enhanced chemical vapor deposition silicon oxynitride optimized for application in integrated optics

    NARCIS (Netherlands)

    Worhoff, Kerstin; Driessen, A.; Lambeck, Paul; Hilderink, L.T.H.; Linders, Petrus W.C.; Popma, T.J.A.

    1999-01-01

    Silicon Oxynitride layers are grown from SiH4/N2, NH3 and N2O by Plasma Enhanced Chemical Vapor Deposition. The process is optimized with respect to deposition of layers with excellent uniformity in the layer thickness, high homogeneity of the refractive index and good reproducibility of the layer

  14. Effect of Different Catalyst Deposition Technique on Aligned Multiwalled Carbon Nanotubes Grown by Thermal Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    Mohamed Shuaib Mohamed Saheed

    2014-01-01

    Full Text Available The paper reported the investigation of the substrate preparation technique involving deposition of iron catalyst by electron beam evaporation and ferrocene vaporization in order to produce vertically aligned multiwalled carbon nanotubes array needed for fabrication of tailored devices. Prior to the growth at 700°C in ethylene, silicon dioxide coated silicon substrate was prepared by depositing alumina followed by iron using two different methods as described earlier. Characterization analysis revealed that aligned multiwalled carbon nanotubes array of 107.9 µm thickness grown by thermal chemical vapor deposition technique can only be achieved for the sample with iron deposited using ferrocene vaporization. The thick layer of partially oxidized iron film can prevent the deactivation of catalyst and thus is able to sustain the growth. It also increases the rate of permeation of the hydrocarbon gas into the catalyst particles and prevents agglomeration at the growth temperature. Combination of alumina-iron layer provides an efficient growth of high density multiwalled carbon nanotubes array with the steady growth rate of 3.6 µm per minute for the first 12 minutes and dropped by half after 40 minutes. Thicker and uniform iron catalyst film obtained from ferrocene vaporization is attributed to the multidirectional deposition of particles in the gaseous form.

  15. Remote microwave plasma enhanced chemical vapor deposition (RMPECVD) of silica and alumina films

    Energy Technology Data Exchange (ETDEWEB)

    Desmaison, J.; Hidalgo, H.; Tristant, P.; Naudin, F.; Merle, D. [Limoges Univ. (France). Lab. de Sciences des Procedes Ceramiques et Traitements de Surface

    2002-07-01

    Alumina or silica are attractive as insulation and protective layers for sensitive substrates. Oxides are deposited by remote microwave plasma enhanced chemical vapor deposition (RMPECVD) using an oxygen plasma and a mixture of precursor gas silane or trimethylaluminum (TMA) diluted in argon, respectively for silica and alumina, injected in the afterglow. This technique allows to deposit films of SiO{sub 2} and Al{sub 2}O{sub 3} with satisfactory characteristics (density, etch rate, stoichiometry) and high deposition rate. The comparison of the best deposition conditions reveals that in case of alumina higher temperatures and lower pressures are needed. (orig.)

  16. Preparation of silver thin films using liquid-phase precursors by metal organic chemical vapor deposition and their conversion to silver selenide films by selenium vapor deposition

    International Nuclear Information System (INIS)

    Kim, Hong-Ki; Jeong, Han-Cheol; Kim, Kyung Soo; Yoon, Seok Hwan; Lee, Seung Soo; Seo, Kook Won; Shim, Il-Wun

    2005-01-01

    A series of new Ag precursors containing β-diketonate and neutral phosphite ligands were synthesized and characterized by various spectroscopic methods. These volatile precursors in liquid phase were thermally stable and quite useful in the preparation of silver thin films through bubbler-type chemical vapor deposition (CVD). In a typical case of silver (I) 1,1,1-trifluoro-2,4-pentanedionate triethyl phosphite adduct ((tfac)AgP(OEt) 3 ) precursor, very pure silver thin films were obtained under relatively mild conditions without any appreciable amount of F, O, and P impurities. These thin films were easily converted to β-orthorhombic silver selenide by simple selenium vapor deposition method. In scanning electron microscopic analyses, the average particle size of the latter was found to increase to about 1.26 μm after gas-phase selenization reaction

  17. Metal-organic chemical vapor deposition enabling all-solid-state Li-ion microbatteries:a short review

    OpenAIRE

    Chen, C; Eichel, R-A; Notten, PHL Peter

    2017-01-01

    For powering small-sized electronic devices, all-solid-state Li-ion batteries are the most promising candidates due to its safety and allowing miniaturization. Thin film deposition methods can be used for building new all-solid-state architectures. Well-known deposition methods are sputter deposition, pulsed laser deposition, sol-gel deposition, atomic layer deposition, etc. This review summarizes thin film storage materials deposited by metal-organic chemical vapor deposition (MOCVD) for all...

  18. Half-sandwich cobalt complexes in the metal-organic chemical vapor deposition process

    Energy Technology Data Exchange (ETDEWEB)

    Georgi, Colin [Technische Universität Chemnitz, Faculty of Natural Science, Institute of Chemistry, Inorganic Chemistry, Chemnitz 09107 (Germany); Hapke, Marko; Thiel, Indre [Leibniz-Institut für Katalyse e.V. an der Universität Rostock (LIKAT), Albert-Einstein-Straße 29a, Rostock 18059 (Germany); Hildebrandt, Alexander [Technische Universität Chemnitz, Faculty of Natural Science, Institute of Chemistry, Inorganic Chemistry, Chemnitz 09107 (Germany); Waechtler, Thomas; Schulz, Stefan E. [Fraunhofer Institute of Electronic Nano Systems (ENAS), Technologie-Campus 3, Chemnitz 09126 (Germany); Technische Universität Chemnitz, Center for Microtechnologies (ZfM), Chemnitz 09107 (Germany); Lang, Heinrich, E-mail: heinrich.lang@chemie.tu-chemnitz.de [Technische Universität Chemnitz, Faculty of Natural Science, Institute of Chemistry, Inorganic Chemistry, Chemnitz 09107 (Germany)

    2015-03-02

    A series of cobalt half-sandwich complexes of type [Co(η{sup 5}-C{sub 5}H{sub 5})(L)(L′)] (1: L, L′ = 1,5-hexadiene; 2: L = P(OEt){sub 3}, L′ = H{sub 2}C=CHSiMe{sub 3}; 3: L = L′ = P(OEt){sub 3}) has been studied regarding their physical properties such as the vapor pressure, decomposition temperature and applicability within the metal-organic chemical vapor deposition (MOCVD) process, with a focus of the influence of the phosphite ligands. It could be shown that an increasing number of P(OEt){sub 3} ligands increases the vapor pressure and thermal stability of the respective organometallic compound. Complex 3 appeared to be a promising MOCVD precursor with a high vapor pressure and hence was deposited onto Si/SiO{sub 2} (100 nm) substrates. The resulting reflective layer is closed, dense and homogeneous, with a slightly granulated surface morphology. X-ray photoelectron spectroscopy (XPS) studies demonstrated the formation of metallic cobalt, cobalt phosphate, cobalt oxide and cobalt carbide. - Highlights: • Thermal studies and vapor pressure measurements of cobalt half-sandwich complexes was carried out. • Chemical vapor deposition with cobalt half-sandwich complexes is reported. • The use of Co-phosphites results in significant phosphorous-doped metallic layers.

  19. Laser Induced Chemical Vapor Deposition of Thin Films

    National Research Council Canada - National Science Library

    Zahavi, Joseph

    1995-01-01

    .... It completes the information which was given in the previous two progress reports. Basically, the aim of the first year was to study the possibility of deposition of silicon nitride thin films from silane and ammonia at low temperatures...

  20. Si Passivation and Chemical Vapor Deposition of Silicon Nitride: Final Technical Report, March 18, 2007

    Energy Technology Data Exchange (ETDEWEB)

    Atwater, H. A.

    2007-11-01

    This report investigated chemical and physical methods for Si surface passivation for application in crystalline Si and thin Si film photovoltaic devices. Overall, our efforts during the project were focused in three areas: i) synthesis of silicon nitride thin films with high hydrogen content by hot-wire chemical vapor deposition; ii) investigation of the role of hydrogen passivation of defects in crystalline Si and Si solar cells by out diffusion from hydrogenated silicon nitride films; iii) investigation of the growth kinetics and passivation of hydrogenated polycrystalline. Silicon nitride films were grown by hot-wire chemical vapor deposition and film properties have been characterized as a function of SiH4/NH3 flow ratio. It was demonstrated that hot-wire chemical vapor deposition leads to growth of SiNx films with controllable stoichiometry and hydrogen.

  1. Chemical vapor deposition of graphene at very low pressures

    OpenAIRE

    Thiago Henrique Rodrigues da Cunha

    2014-01-01

    A deposição química de vapor (CVD) de hidrocarbonetos vem se tornando um paradigma para a produção de grafeno em larga escala. No entanto, os mecanismos de crescimento associados ao processo ainda não são totalmente compreendidos, de forma que ainda não é possível um controle sistemático da qualidade dos filmes sintetizados. Nesta tese, apresentamos uma investigação detalhada do crescimento de grafeno por CVD à baixa pressão em um reator de parede fria, utilizando substratos de cobre. Uma com...

  2. Chemical Vapor Transport Deposition of Molybdenum Disulfide Layers Using H2O Vapor as the Transport Agent

    Directory of Open Access Journals (Sweden)

    Shichao Zhao

    2018-02-01

    Full Text Available Molybdenum disulfide (MoS2 layers show excellent optical and electrical properties and have many potential applications. However, the growth of high-quality MoS2 layers is a major bottleneck in the development of MoS2-based devices. In this paper, we report a chemical vapor transport deposition method to investigate the growth behavior of monolayer/multi-layer MoS2 using water (H2O as the transport agent. It was shown that the introduction of H2O vapor promoted the growth of MoS2 by increasing the nucleation density and continuous monolayer growth. Moreover, the growth mechanism is discussed.

  3. Modeling free convective gravitational effects in chemical vapor deposition

    Science.gov (United States)

    Stinespring, C. D.; Annen, K. D.

    1987-01-01

    In this paper, a combined fluid-mechanics, mass-transport, and chemistry model describing CVD in an open-tube atmospheric-pressure flow reactor is developed. The model allows gas-phase reactions to proceed to equilibrium and accounts for finite reaction rates at the surface of the deposition substrate. This model is a useful intermediate step toward a model employing fully rate-limited chemistry. The model is used to predict the effects of free convection on flow patterns, temperature and species-concentration profiles, and local deposition rates for silicon deposited by silane pyrolysis. These results are discussed in terms of implications for CVD of silicon and other compounds, microgravity studies, and techniques for testing and validating the model.

  4. Experimental verification of corrosive vapor deposition rate theory in high velocity burner rigs

    Science.gov (United States)

    Gokoglu, Suleyman A.; Santoro, Gilbert J.

    1986-01-01

    The ability to predict deposition rates is required to facilitate modelling of high temperature corrosion by fused salt condensates in turbine engines. A corrosive salt vapor deposition theory based on multicomponent chemically frozen boundary layers (CFBL) has been successfully verified by high velocity burner rig experiments. The experiments involved internally air-impingement cooled, both rotating full and stationary segmented cylindrical collectors located in the crossflow of sodium-seeded combustion gases. Excellent agreement is found between the CFBL theory and the experimental measurements for both the absolute amounts of Na2SO4 deposition rates and the behavior of deposition rate with respect to collector temperature, mass flowrate (velocity) and Na concentration.

  5. On diffusion-controlled interface microstructure of vapor deposited ...

    Indian Academy of Sciences (India)

    after deposition could be explained by the existing laws, the profiles for others are found to be distinctly different and are ... Thickness of the layers removed is obtained by calibrating the time of etching at a given Ar+ ion gun set- ... of the Fourier series solution of the Fick's law for isothermal diffusion with a con- stant diffusion ...

  6. Effect of post-deposition annealing on low temperature metalorganic chemical vapor deposited gallium oxide related materials

    Science.gov (United States)

    Takiguchi, Yuki; Miyajima, Shinsuke

    2017-06-01

    Low temperature metalorganic chemical vapor deposition using trimethylgallium and water was investigated. The surface morphology of the film was almost flat at a deposition temperature below 182 °C. This flat film was a mixture of nanocrystalline and amorphous phase. The film deposited at a temperature of 272 °C resulted in a nanowire structure. X-ray diffraction measurements revealed that the nanowire film was a mixture of gallium hydroxide, gallium oxyhydroxide, and gallium tohdite or gallium oxide. We also found that post-deposition annealing above 600 °C significantly changed the crystal structure of the both flat and nanowire films. Monoclinic gallium oxide phase was dominant after the post-deposition annealing above 600 °C.

  7. Chemical vapor deposition polymerization the growth and properties of parylene thin films

    CERN Document Server

    Fortin, Jeffrey B

    2004-01-01

    Chemical Vapor Deposition Polymerization - The Growth and Properties of Parylene Thin Films is intended to be valuable to both users and researchers of parylene thin films. It should be particularly useful for those setting up and characterizing their first research deposition system. It provides a good picture of the deposition process and equipment, as well as information on system-to-system variations that is important to consider when designing a deposition system or making modifications to an existing one. Also included are methods to characterizae a deposition system's pumping properties as well as monitor the deposition process via mass spectrometry. There are many references that will lead the reader to further information on the topic being discussed. This text should serve as a useful reference source and handbook for scientists and engineers interested in depositing high quality parylene thin films.

  8. High quality plasma-enhanced chemical vapor deposited silicon nitride films

    Energy Technology Data Exchange (ETDEWEB)

    Cotler, T.J.; Chapple-Sokol, J. (IBM General Technology Division, Hopewell Junction, NY (United States))

    1993-07-01

    The qualities of plasma-enhanced chemical vapor deposited (PECVD) silicon nitride films can be improved by increasing the deposition temperature. This report compares PECVD silicon nitride films to low pressure chemical vapor deposited (LPCVD) films. The dependence of the film properties on process parameters, specifically power and temperature, are investigated. The stress is shown to shift from tensile to compressive with increasing temperature and power. The deposition rate, uniformity, wet etch rate, index of refraction, composition, stress, hydrogen content, and conformality are considered to evaluate the film properties. Temperature affects the hydrogen content in the films by causing decreased incorporation of N-H containing species whereas the dependence on power is due to changes in the gas-phase precursors. All PECVD film properties, with the exception of conformality, are comparable to those of LPCVD films.

  9. The development of chemically vapor deposited mullite coatings for the corrosion protection of SiC

    Energy Technology Data Exchange (ETDEWEB)

    Auger, M.; Hou, P.; Sengupta, A.; Basu, S.; Sarin, V. [Boston Univ., MA (United States)

    1998-05-01

    Crystalline mullite coatings have been chemically vapor deposited onto SiC substrates to enhance the corrosion and oxidation resistance of the substrate. Current research has been divided into three distinct areas: (1) Development of the deposition processing conditions for increased control over coating`s growth rate, microstructure, and morphology; (2) Analysis of the coating`s crystal structure and stability; (3) The corrosion resistance of the CVD mullite coating on SiC.

  10. A Review of Metalorganic Chemical Vapor Deposition of High-Temperature Superconducting Thin Films

    Science.gov (United States)

    Erbil, Ahmet; Zhang, K.; Kwak, B. S.; Boyd, E. P.

    1990-03-01

    A status report is given on the metalorganic chemical vapor deposition (MOCVD) of high-temperature superconducting thin films. The advantages of MOCVD processing manifest themselves in the quality of the films produced, and in the economy of the process. Metalorganic precursor requirements, deposition parameters and film properties are discussed. Also difficulties have been identified in making MOCVD a manufacturing technology. To solve these problems, future research directions are proposed.

  11. Development of a Computational Chemical Vapor Deposition Model: Applications to Indium Nitride and Dicyanovinylaniline

    Science.gov (United States)

    Cardelino, Carlos

    1999-01-01

    A computational chemical vapor deposition (CVD) model is presented, that couples chemical reaction mechanisms with fluid dynamic simulations for vapor deposition experiments. The chemical properties of the systems under investigation are evaluated using quantum, molecular and statistical mechanics models. The fluid dynamic computations are performed using the CFD-ACE program, which can simulate multispecies transport, heat and mass transfer, gas phase chemistry, chemistry of adsorbed species, pulsed reactant flow and variable gravity conditions. Two experimental setups are being studied, in order to fabricate films of: (a) indium nitride (InN) from the gas or surface phase reaction of trimethylindium and ammonia; and (b) 4-(1,1)dicyanovinyl-dimethylaminoaniline (DCVA) by vapor deposition. Modeling of these setups requires knowledge of three groups of properties: thermodynamic properties (heat capacity), transport properties (diffusion, viscosity, and thermal conductivity), and kinetic properties (rate constants for all possible elementary chemical reactions). These properties are evaluated using computational methods whenever experimental data is not available for the species or for the elementary reactions. The chemical vapor deposition model is applied to InN and DCVA. Several possible InN mechanisms are proposed and analyzed. The CVD model simulations of InN show that the deposition rate of InN is more efficient when pulsing chemistry is used under conditions of high pressure and microgravity. An analysis of the chemical properties of DCVA show that DCVA dimers may form under certain conditions of physical vapor transport. CVD simulations of the DCVA system suggest that deposition of the DCVA dimer may play a small role in the film and crystal growth processes.

  12. Synthesis of multifilament silicon carbide fibers by chemical vapor deposition

    Science.gov (United States)

    Revankar, Vithal; Hlavacek, Vladimir

    1991-01-01

    A process for development of clean silicon carbide fiber with a small diameter and high reliability is presented. An experimental evaluation of operating conditions for SiC fibers of good mechanical properties and devising an efficient technique which will prevent welding together of individual filaments are discussed. The thermodynamic analysis of a different precursor system was analyzed vigorously. Thermodynamically optimum conditions for stoichiometric SiC deposit were obtained.

  13. Carbon Nanoparticle-Supported Pd Obtained by Solar Physical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    Alexandru Pascu

    2018-01-01

    Full Text Available Palladium supported on carbon nanoparticles has been obtained on a specially designed ceramic catalyst, obtained by thermal spraying on a copper substrate, starting from Pd/C targets. Solar physical vapor deposition in argon, an environment-friendly and energy-efficient alternative to arc or chemical vapor deposition, has been employed as a means of target vaporization at CNRS-PROMES facility in Odeillo, France. The obtained nanoparticles have a spherical-porous morphology with diameters ranging from 50 to 120 nm and specific sorption areas of 50,000 m2/g. The XRD diffractograms indicate the presence of dominatingly crystalline short-range ordered graphene oxide layers, in contrast with the amorphous Pd/C starting precursor. The presence of palladium (0.6% wt. at the surface of the nanoparticles was proved by the EDX and XRD analyses, making the synthesized material useful in applications such as catalysis or gas sorption.

  14. Influence of the catalyst type on the growth of carbon nanotubes via methane chemical vapor deposition

    NARCIS (Netherlands)

    Jodin, Lucie; Dupuis, Anne-Claire; Rouvière, Emmanuelle; Reiss, Peter

    2006-01-01

    The preparation of the catalyst is one of the key parameters which governs the quality of carbon nanotubes (CNTs) grown by catalyzed chemical vapor deposition (CVD). We investigated the influence of three different procedures of catalyst preparation on the type and diameter of CNTs formed under

  15. Monitoring the chemical vapor deposition growth of multiwalled carbon nanotubes by tapered element oscillating microbalance

    Czech Academy of Sciences Publication Activity Database

    Švrček, Vladimír; Kleps, I.; Cracioniou, F.; Paillaud, J.L.; Dintzer, T.; Louis, B.; Begin, D.; Pham-Huu, C.; Ledoux, M.-J.; Le Normand, F.

    2006-01-01

    Roč. 124, č. 18 (2006), 184705/1-184705/11 ISSN 0021-9606 Grant - others:NANOTEMP(XE) HPRN-CT-2002-00192 Institutional research plan: CEZ:AV0Z10100521 Keywords : multiwalled carbon nanotubes (MWCNTs) * growth kinetics * catalytic chemical vapor deposition (CCVD) Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.166, year: 2006

  16. Mechanical properties of vapor-deposited thin metallic films: a status report

    International Nuclear Information System (INIS)

    Adler, P.H.

    1982-01-01

    The mechanical properties of vapor-deposited thin metallic films are being studied in conjunction with the target fabrication group associated with the laser-fusion energy program. The purpose of the work is to gain an understanding as to which metals are structurally best suited to contain a glass microsphere filled with deuterium-tritium (D-T) gas at large internal pressures

  17. Industrial Scale Synthesis of Carbon Nanotubes Via Fluidized Bed Chemical Vapor Deposition: A Senior Design Project

    Science.gov (United States)

    Smith, York R.; Fuchs, Alan; Meyyappan, M.

    2010-01-01

    Senior year chemical engineering students designed a process to produce 10 000 tonnes per annum of single wall carbon nanotubes (SWNT) and also conducted bench-top experiments to synthesize SWNTs via fluidized bed chemical vapor deposition techniques. This was an excellent pedagogical experience because it related to the type of real world design…

  18. 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

  19. Kinetic Study of the Chemical Vapor Deposition of Tantalum in Long Narrow Channels

    DEFF Research Database (Denmark)

    Mugabi, James Atwoki; Eriksen, Søren; Petrushina, Irina

    2016-01-01

    A kinetic study of the chemical vapor deposition of tantalum in long narrow channels is done to optimize the industrial process for the manufacture of tantalum coated plate heat exchangers. The developed model fits well at temperatures between 750 and 850 °C, and in the pressure range of25–990 mbar...

  20. Closed-loop control of laser assisted chemical vapor deposition growth of carbon nanotubes

    NARCIS (Netherlands)

    Burgt, Y. van de; Bellouard, Y.; Mandamparambil, R.; Haluska, M.; Dietzel, A.H.

    2012-01-01

    Laser-assisted chemical vapor deposition growth is an attractive mask-less process for growing locally aligned nanotubes in selected places on temperature sensitive substrates. An essential parameter for a successful and reproducible synthesis of nanotubes is the temperature during growth. Here, we

  1. Controllable chemical vapor deposition of large area uniform nanocrystalline graphene directly on silicon dioxide

    DEFF Research Database (Denmark)

    Sun, Jie; Lindvall, Niclas; Cole, Matthew T.

    2012-01-01

    Metal-catalyst-free chemical vapor deposition (CVD) of large area uniform nanocrystalline graphene on oxidized silicon substrates is demonstrated. The material grows slowly, allowing for thickness control down to monolayer graphene. The as-grown thin films are continuous with no observable pinhol...

  2. In situ observations during chemical vapor deposition of hexagonal boron nitride on polycrystalline copper

    DEFF Research Database (Denmark)

    Kidambi, Piran R.; Blume, Raoul; Kling, Jens

    2014-01-01

    Using a combination of complementary in situ X-ray photoelectron spectroscopy and X-ray diffraction, we study the fundamental mechanisms underlying the chemical vapor deposition (CVD) of hexagonal boron nitride (h-BN) on polycrystalline Cu. The nucleation and growth of h-BN layers is found to occ...

  3. Coating of ceramic powders by chemical vapor deposition techniques (CVD)

    International Nuclear Information System (INIS)

    Haubner, R.; Lux, B.

    1997-01-01

    New ceramic materials with selected advanced properties can be designed by coating of ceramic powders prior to sintering. By variation of the core and coating material a large number of various powders and ceramic materials can be produced. Powders which react with the binder phase during sintering can be coated with stable materials. Thermal expansion of the ceramic materials can be adjusted by varying the coating thickness (ratio core/layer). Electrical and wear resistant properties can be optimized for electrical contacts. A fluidized bed reactor will be designed which allow the deposition of various coatings on ceramic powders. (author)

  4. Two dimensional radial gas flows in atmospheric pressure plasma-enhanced chemical vapor deposition

    Science.gov (United States)

    Kim, Gwihyun; Park, Seran; Shin, Hyunsu; Song, Seungho; Oh, Hoon-Jung; Ko, Dae Hong; Choi, Jung-Il; Baik, Seung Jae

    2017-12-01

    Atmospheric pressure (AP) operation of plasma-enhanced chemical vapor deposition (PECVD) is one of promising concepts for high quality and low cost processing. Atmospheric plasma discharge requires narrow gap configuration, which causes an inherent feature of AP PECVD. Two dimensional radial gas flows in AP PECVD induces radial variation of mass-transport and that of substrate temperature. The opposite trend of these variations would be the key consideration in the development of uniform deposition process. Another inherent feature of AP PECVD is confined plasma discharge, from which volume power density concept is derived as a key parameter for the control of deposition rate. We investigated deposition rate as a function of volume power density, gas flux, source gas partial pressure, hydrogen partial pressure, plasma source frequency, and substrate temperature; and derived a design guideline of deposition tool and process development in terms of deposition rate and uniformity.

  5. Characterization of photoluminescent europium doped yttrium oxide thin-films prepared by metallorganic chemical vapor deposition

    International Nuclear Information System (INIS)

    McKittrick, J.; Bacalski, C.F.; Hirata, G.A.; Hubbard, K.M.; Pattillo, S.G.; Salazar, K.V.; Trkula, M.

    1998-01-01

    Europium doped yttrium oxide, (Y 1-x Eu x ) 2 O 3 , thin-films were deposited on silicon and sapphire substrates by metallorganic chemical vapor deposition (MOCVD). The films were grown in a MOCVD chamber reacting yttrium and europium tris(2,2,6,6-tetramethyl-3,5,-heptanedionates) precursors in an oxygen atmosphere at low pressures (5 Torr) and low substrate temperatures (500--700 C). The films deposited at 500 C were flat and composed of nanocrystalline regions of cubic Y 2 O 3 , grown in a textured [100] or [110] orientation to the substrate surface. Films deposited at 600 C developed from the flat, nanocrystalline morphology into a plate-like growth morphology oriented in the [111] with increasing deposition time. Monoclinic Y 2 O 3 :Eu 3+ was observed in x-ray diffraction for deposition temperatures ≥600 C on both (111) Si and (001) sapphire substrates. This was also confirmed by the photoluminescent emission spectra

  6. Investigating the kinetic stability and transformation of vapor-deposited glasses with AC nanocalorimetry experiments

    Science.gov (United States)

    Tylinski, Michael Tod

    This thesis presents experiments and discussion that advance the understanding of vapor-deposited glasses. When vapor-deposited glasses exhibit high kinetic stability, they're known as stable glasses. Stable glasses are known to transform into the liquid state via a front mechanism. My first project introduced a quantitative evaluation of the uniformity of these fronts over time and space. I found that the front velocity varies by less than 4% over the duration of the transformation. For films 280 nm thick, the transformation rates at different spatial positions in the film differ by about 25%; this quantity may be related to spatially heterogeneous dynamics in the stable glass. In my second project, I established that vapor deposition could be used to prepare stable glasses of an alcohol molecule. It was previously unknown if this was possible. I also found that while at least one alcohol molecule can be used to prepare a stable glass, several other alcohol molecules formed glasses with minimal kinetic stability when using standard deposition conditions. The wide range of kinetic stabilities is useful for investigating the factors that control stable glass formation. I compared the kinetic stability of vapor deposited glasses prepared from 14 molecules and found a correlation with the value of taualpha at 1.25 Tg. In my final research project, I performed experiments that tested various hypotheses for why 2-ethyl-1-hexanol forms vapor-deposited glasses with limited kinetic stability when using standard preparation conditions. The experiments supported the hypothesis that the surface mobility is less than for other molecules that are used to prepare stable glasses. My analysis of the data led to the estimation that at the substrate temperature commonly used to deposit stable glasses, 2-ethyl-1-hexanol molecules at the surface move more than 104 times slower compared to molecules that do form highly stable glasses using typical preparation conditions. The thesis

  7. Effects of argon and oxygen flow rate on water vapor barrier properties of silicon oxide coatings deposited on polyethylene terephthalate by plasma enhanced chemical vapor deposition

    International Nuclear Information System (INIS)

    Kim, Sung-Ryong; Choudhury, Moinul Haque; Kim, Won-Ho; Kim, Gon-Ho

    2010-01-01

    Plasma polymer coatings were deposited from hexamethyldisiloxane on polyethylene terephthalate (PET) substrates while varying the operating conditions, such as the Ar and O 2 flow rates, at a fixed radio frequency power of 300 W. The water vapor transmission rate (WVTR) of the untreated PET was 54.56 g/m 2 /day and was decreased after depositing the silicon oxide (SiO x ) coatings. The minimum WVTR, 0.47 g/m 2 /day, was observed at Ar and O 2 flow rates of 4 and 20 sccm, respectively, with a coating thickness of 415.44 nm. The intensity of the peaks for the Si-O-Si bending at 800-820 cm -1 and Si-O-Si stretching at 1000-1150 cm -1 varied depending on the Ar and O 2 flow rates. The contact angle of the SiO x coated PET increased as the Ar flow rate was increased from 2 to 8 sccm at a fixed O 2 flow rate of 20 sccm. It decreased gradually as the oxygen flow rate increased from 12 to 28 sccm at a fixed Ar carrier gas flow rate. The examination by atomic force microscopy revealed a correlation of the SiO x morphology and the water vapor barrier performance with the Ar and O 2 flow rates. The roughness of the deposited coatings increased when either the O 2 or Ar flow rate was increased.

  8. CuOX thin films by direct oxidation of Cu films deposited by physical vapor deposition

    Directory of Open Access Journals (Sweden)

    D. Santos-Cruz

    Full Text Available Thin films of Cu2O and CuO oxides were developed by direct oxidation of physical vapor deposited copper films in an open atmosphere by varying the temperature in the range between 250 and 400 °C. In this work, the influence of oxidation temperature on structural, optical and electrical properties of copper oxide films has been discussed. The characterization results revealed that at lower temperatures (<300 °C, it is feasible to obtained coper (I oxide whereas at temperatures higher than 300 °C, the copper (II oxide is formed. The band gap is found to vary in between 1.54 and 2.21 eV depending on the oxidation temperature. Both oxides present p-type electrical conductivity. The carrier concentration has been increased as a function of the oxidation temperature from 1.61 × 1012 at 250 °C to 6.8 × 1012 cm−3 at 400 °C. The mobility has attained its maximum of 34.5 cm2 V−1 s−1 at a temperature of 300 °C, and a minimum of 13.8 cm2 V−1 s−1 for 400 °C. Finally, the resistivity of copper oxide films decreases as a function of oxidation temperature from 5.4 × 106 to 2.4 × 105 Ω-cm at 250 and 400 °C, respectively. Keywords: PVD, Oxidizing annealed treatment, Non-toxic material

  9. Quasi-Isentropic Compression of Vapor Deposited Hexanitroazobenzene (HNAB): Experiments and Analysis

    Science.gov (United States)

    Yarrington, Cole; Tappan, Alexander; Specht, Paul; Knepper, Robert

    2017-06-01

    Vapor-deposited hexanitroazobenzene (HNAB) is an explosive with unique physical characteristics resulting from the deposition process that make it desirable for the study of microstructure effects. A relatively understudied high explosive (HE), few data are available on the equation of state (EOS) of HNAB reactants or products. HNAB samples exhibiting high density and sub-micron porosity and grain size were prepared using physical vapor deposition onto polymethyl methacrylate (PMMA) and lithium fluoride (LiF) substrates. The samples were quasi-isentropically ramp compressed using VELOCE, a compact pulsed power generator. Evidence of a low pressure phase transition was observed in HNAB. Interferometric measurements of reference and sample interface velocities enabled inference of the unreacted EOS for HNAB using DAKOTA, an optimization toolkit. Initial simulations of the HNAB critical thickness experiment have been carried out using the parameterized EOS, and a products EOS from thermal equilibrium calculations.

  10. Sequential microcontroller-based control for a chemical vapor deposition process

    Directory of Open Access Journals (Sweden)

    Edgar Serrano Pérez

    2017-12-01

    Full Text Available A cost-effective direct liquid injection system is developed for a chemical vapor deposition process using a microcontroller. The precursor gas phase is controlled by the precise sequential injection of a liquid precursor solution to a vaporizing chamber prior deposition. The electronic control system allows the human–machine interface through a LCD display and a keypad matrix. The core of the electronic system is based on an electro mechanical injector operated in time and frequency as a sequential control system by a popular PIC16F877A chip. The software has been developed in the BASIC language and it can be easily modified through an ICSP programmer for different sequential automatized routines. The injection calibration test has proven the linearity of the injection control system for different operation parameters. The results reported the sequential injection MOCVD deposition of alumina thin film.

  11. Reactive Chemical Vapor Deposition Method as New Approach for Obtaining Electroluminescent Thin Film Materials

    Directory of Open Access Journals (Sweden)

    Valentina V. Utochnikova

    2012-01-01

    Full Text Available The new reactive chemical vapor deposition (RCVD method has been proposed for thin film deposition of luminescent nonvolatile lanthanide aromatic carboxylates. This method is based on metathesis reaction between the vapors of volatile lanthanide dipivaloylmethanate (Ln(dpm3 and carboxylic acid (HCarb orH2Carb′ and was successfully used in case of HCarb. Advantages of the method were demonstrated on example of terbium benzoate (Tb(bz3 and o-phenoxybenzoate thin films, and Tb(bz3 thin films were successfully examined in the OLED with the following structure glass/ITO/PEDOT:PSS/TPD/Tb(bz3/Ca/Al. Electroluminescence spectra of Tb(bz3 showed only typical luminescent bands, originated from transitions of the terbium ion. Method peculiarities for deposition of compounds of dibasic acids H2Carb′ are established on example of terbium and europium terephtalates and europium 2,6-naphtalenedicarboxylate.

  12. Laser chemical vapor deposition of millimeter scale three-dimensional shapes

    Science.gov (United States)

    Shaarawi, Mohammed Saad

    2001-07-01

    Laser chemical vapor deposition (LCVD) has been successfully developed as a technique to synthesize millimeter-scale components directly from the gas phase. Material deposition occurs when heat generated by the interaction of a laser beam with a substrate thermally decomposes the gas precursor. Selective illumination or scanning the laser beam over portions of a substrate forms the single thin layer of material that is the building block of this process. Sequential scanning of the laser in a pre-defined pattern on the substrate and subsequent deposit causes the layers to accumulate forming the three-dimensional shape. The primary challenge encountered in LCVD shape forming is the synthesis of uniform layers. Three deposition techniques are studied to address this problem. The most successful technique, Active Surface Deposition, is based on the premise that the most uniform deposits are created by measuring the deposition surface topology and actively varying the deposition rate in response to features at the deposition surface. Defects observed in the other techniques were significantly reduced or completely eliminated using Active Surface Deposition. The second technique, Constant Temperature Deposition, maintains deposit uniformity through the use of closed-loop modulation of the laser power to sustain a constant surface temperature during deposition. The technique was successful in depositing high quality graphite tubes >2 mm tall from an acetylene precursor and partially successful in depositing SiC + C composite tubes from tetramethylsilane (TMS). The final technique, Constant Power Deposition, is based on the premise that maintaining a uniform power output throughout deposition would result in the formation of uniform layers. Constant Power Deposition failed to form coherent shapes. Additionally, LCVD is studied using a combination of analytic and numerical models to gain insight into the deposition process. Thermodynamic modeling is used to predict the

  13. Progress Toward Meeting NIF Specifications for Vapor Deposited Polyimide Ablator Coatings

    International Nuclear Information System (INIS)

    Letts, Stephan A.; Anthamatten, Mitchell; Buckley, Steven R.; Fearon, Evelyn; Nissen, April E.H.; Cook, Robert C.

    2004-01-01

    We are developing an evaporative coating technique for deposition of thick polyimide (PI) ablator layers on ICF targets. The PI coating technique utilizes stoichiometrically controlled fluxes from two Knudsen cell evaporators containing a dianhydride and a diamine to deposit a polyamic acid (PAA) coating. Heating the PAA coating to 300 deg. C converts the PAA coating to a polyimide. Coated shells are rough due to particles on the substrate mandrels and from damage to the coating caused by the agitation used to achieve a uniform coating. We have developed a smoothing process that exposes an initially rough PAA coated shell to solvent vapor using gas levitation. We found that after smoothing the coatings developed a number of wide (low-mode) defects. We have identified two major contributors to low-mode roughness: surface hydrolysis, and deformation during drying/curing. By minimizing air exposure prior to vapor smoothing, avoiding excess solvent sorption during vapor smoothing, and using slow drying we are able to deposit and vapor smooth coatings 160 μm thick with a surface roughness less than 20 nm RMS

  14. Gaseous material capacity of open plasma jet in plasma spray-physical vapor deposition process

    Science.gov (United States)

    Liu, Mei-Jun; Zhang, Meng; Zhang, Qiang; Yang, Guan-Jun; Li, Cheng-Xin; Li, Chang-Jiu

    2018-01-01

    Plasma spray-physical vapor deposition (PS-PVD) process, emerging as a highly efficient hybrid approach, is based on two powerful technologies of both plasma spray and physical vapor deposition. The maximum production rate is affected by the material feed rate apparently, but it is determined by the material vapor capacity of transporting plasma actually and essentially. In order to realize high production rate, the gaseous material capacity of plasma jet must be fundamentally understood. In this study, the thermal characteristics of plasma were measured by optical emission spectrometry. The results show that the open plasma jet is in the local thermal equilibrium due to a typical electron number density from 2.1 × 1015 to 3.1 × 1015 cm-3. In this condition, the temperature of gaseous zirconia can be equal to the plasma temperature. A model was developed to obtain the vapor pressure of gaseous ZrO2 molecules as a two dimensional map of jet axis and radial position corresponding to different average plasma temperatures. The overall gaseous material capacity of open plasma jet, take zirconia for example, was further established. This approach on evaluating material capacity in plasma jet would shed light on the process optimization towards both depositing columnar coating and a high production rate of PS-PVD.

  15. Growths of indium gallium nitride nanowires by plasma-assisted chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Wei-Che [Department of Chemical Engineering, National Cheng Kung University, 1 University Road, Tainan 701, Taiwan (China); Hong, Franklin Chau-Nan, E-mail: hong@mail.ncku.edu.tw [Department of Chemical Engineering, National Cheng Kung University, 1 University Road, Tainan 701, Taiwan (China); Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 701, Taiwan (China); Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 701, Taiwan (China)

    2014-11-03

    InGaN nanowires (NWs) were grown on Si(100) at 700 °C using Au catalyst in a plasma-assisted chemical vapor deposition reactor. As the indium vapor pressure was low around 16 mPa during the growths, only the curved GaN NWs could be grown containing indium impurities. By increasing the indium vapor pressure to 53 mPa during the growths, InGaN NWs were transformed to less curved NWs with a broad distribution of NW diameters from 20 to 90 nm. The room temperature photoluminescence of InGaN NWs grown at a high indium vapor pressure showed a broad emission peak at 417 nm, corresponding to an average of 14.5% indium composition in the NWs, with a large full-width at half maximum of 77 nm. Transmission electron microscopy characterization of InGaN NWs showed that the growth orientation was along [100] for the low indium vapor pressure growths and was transformed to along [001] for the high indium vapor pressure growths. - Highlights: • High-quality single-crystalline InGaN nanowires were synthesized. • The indium content of InGaN nanowires grown at 700 °C did not exceed 15%. • A small amount of indium added into the nanowires induced stacking faults.

  16. Etching Effects During the Chemical Vapor Deposition of (100) Diamond

    Energy Technology Data Exchange (ETDEWEB)

    Battaile, C.C.; Srolovitz, D.J.; Oleinik, I.I.; Pettifor, D.G.; Sutton, A.P.; Harris, S.J.; Butler, J.E.

    1999-08-02

    Current theories of CVD growth on (100) diamond are unable to account for the numerous experimental observations of slow-growing, locally smooth (100)(2x1) films. In this paper they use quantum mechanical calculations of diamond surface thermochemistry and atomic-scale kinetic Monte Carlo simulations of deposition to investigate the efficacy of preferential etching as a mechanism that can help to reconcile this discrepancy. This etching mechanism allows for the removal of undercoordinated carbon atoms from the diamond surface. In the absence of etching, simulated growth on the (100)(2x1) surface is faster than growth on the (110) and (111) surfaces, and the (100) surface is atomically rough. When etching is included in the simulations, the (100) growth rates decrease to values near those observed experimentally, while the rates of growth on the other surfaces remain largely unaffected and similar to those observed experimentally. In addition, the etching mechanism promotes the growth of smooth (100) surface regions in agreement with numerous scanning probe studies.

  17. Modeling film uniformity and symmetry in ionized metal physical vapor deposition with cylindrical targets

    International Nuclear Information System (INIS)

    Lu Junqing; Yang Lin; Yoon, Jae Hong; Cho, Tong Yul; Tao Guoqing

    2008-01-01

    Severe asymmetry of the metal deposits on the trench sidewalls occurs near the wafer edge during low pressure ionized metal physical vapor deposition of Cu seed layer for microprocessor interconnects. To investigate this process and mitigate the asymmetry, an analytical view factor model based on the analogy between metal sputtering and diffuse thermal radiation was constructed to investigate deposition uniformity and symmetry for cylindrical target sputtering in low pressure (below 0.1 Pa) ionized Cu physical vapor deposition. The model predictions indicate that as the distance from the cylindrical target to wafer increases, the metal film thickness becomes more uniform across the wafer and the asymmetry of the metal deposits at the wafer edge increases significantly. These trends are similar to those for planar targets. To minimize the asymmetry, the height of the cylindrical target should be kept at a minimum. For cylindrical targets, the outward-facing sidewall of the trench could receive more direct Cu fluxes than the inward-facing one when the target to wafer distance is short. The predictions also indicate that increasing the diameter of the cylindrical target could significantly reduce the asymmetry in metal deposits at the wafer edge and make the film thickness more uniform across the wafer

  18. Influence of Molecular Shape on the Thermal Stability and Molecular Orientation of Vapor-Deposited Organic Semiconductors.

    Science.gov (United States)

    Walters, Diane M; Antony, Lucas; de Pablo, Juan J; Ediger, M D

    2017-07-20

    High thermal stability and anisotropic molecular orientation enhance the performance of vapor-deposited organic semiconductors, but controlling these properties is a challenge in amorphous materials. To understand the influence of molecular shape on these properties, vapor-deposited glasses of three disk-shaped molecules were prepared. For all three systems, enhanced thermal stability is observed for glasses prepared over a wide range of substrate temperatures and anisotropic molecular orientation is observed at lower substrate temperatures. For two of the disk-shaped molecules, atomistic simulations of thin films were also performed and anisotropic molecular orientation was observed at the equilibrium liquid surface. We find that the structure and thermal stability of these vapor-deposited glasses results from high surface mobility and partial equilibration toward the structure of the equilibrium liquid surface during the deposition process. For the three molecules studied, molecular shape is a dominant factor in determining the anisotropy of vapor-deposited glasses.

  19. A simple method to deposit palladium doped SnO2 thin films using plasma enhanced chemical vapor deposition technique

    International Nuclear Information System (INIS)

    Kim, Young Soon; Wahab, Rizwan; Shin, Hyung-Shik; Ansari, S. G.; Ansari, Z. A.

    2010-01-01

    This work presents a simple method to deposit palladium doped tin oxide (SnO 2 ) thin films using modified plasma enhanced chemical vapor deposition as a function of deposition temperature at a radio frequency plasma power of 150 W. Stannic chloride (SnCl 4 ) was used as precursor and oxygen (O 2 , 100 SCCM) (SCCM denotes cubic centimeter per minute at STP) as reactant gas. Palladium hexafluroacetyleacetonate (Pd(C 5 HF 6 O 2 ) 2 ) was used as a precursor for palladium. Fine granular morphology was observed with tetragonal rutile structure. A peak related to Pd 2 Sn is observed, whose intensity increases slightly with deposition temperature. Electrical resistivity value decreased from 8.6 to 0.9 mΩ cm as a function of deposition temperature from 400 to 600 deg. C. Photoelectron peaks related to Sn 3d, Sn 3p3, Sn 4d, O 1s, and C 1s were detected with varying intensities as a function of deposition temperature.

  20. Effects of deposition temperature and ammonia flow on metal-organic chemical vapor deposition of hexagonal boron nitride

    Science.gov (United States)

    Rice, Anthony; Allerman, Andrew; Crawford, Mary; Beechem, Thomas; Ohta, Taisuke; Spataru, Catalin; Figiel, Jeffrey; Smith, Michael

    2018-03-01

    The use of metal-organic chemical vapor deposition at high temperature is investigated as a means to produce epitaxial hexagonal boron nitride (hBN) at the wafer scale. Several categories of hBN films were found to exist based upon precursor flows and deposition temperature. Low, intermediate, and high NH3 flow regimes were found to lead to fundamentally different deposition behaviors. The low NH3 flow regimes yielded discolored films of boron sub-nitride. The intermediate NH3 flow regime yielded stoichiometric films that could be deposited as thick films. The high NH3 flow regime yielded self-limited deposition with thicknesses limited to a few mono-layers. A Langmuir-Hinshelwood mechanism is proposed to explain the onset of self-limited behavior for the high NH3 flow regime. Photoluminescence characterization determined that the intermediate and high NH3 flow regimes could be further divided into low and high temperature behaviors with a boundary at 1500 °C. Films deposited with both high NH3 flow and high temperature exhibited room temperature free exciton emission at 210 nm and 215.9 nm.

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

    International Nuclear Information System (INIS)

    Zhao, Yuping; Li, Chengchen; Chen, Mingming; Yu, Xiao; Chang, Yunwei; Chen, Anqi; Zhu, Hai; Tang, Zikang

    2016-01-01

    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.

  2. 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.

  3. Atmospheric pressure plasma enhanced chemical vapor deposition of zinc oxide and aluminum zinc oxide

    International Nuclear Information System (INIS)

    Johnson, Kyle W.; Guruvenket, Srinivasan; Sailer, Robert A.; Ahrenkiel, S. Phillip; Schulz, Douglas L.

    2013-01-01

    Zinc oxide (ZnO) and aluminum-doped zinc oxide (AZO) thin films were deposited via atmospheric pressure plasma enhanced chemical vapor deposition. A second-generation precursor, bis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)(N,N′-diethylethylenediamine) zinc, exhibited significant vapor pressure and good stability at one atmosphere where a vaporization temperature of 110 °C gave flux ∼ 7 μmol/min. Auger electron spectroscopy confirmed that addition of H 2 O to the carrier gas stream mitigated F contamination giving nearly 1:1 metal:oxide stoichiometries for both ZnO and AZO with little precursor-derived C contamination. ZnO and AZO thin film resistivities ranged from 14 to 28 Ω·cm for the former and 1.1 to 2.7 Ω·cm for the latter. - Highlights: • A second generation precursor was utilized for atmospheric pressure film growth. • Addition of water vapor to the carrier gas stream led to a marked reduction of ZnF 2 . • Carbonaceous contamination from the precursor was minimal

  4. Development of Single Crystal Chemical Vapor Deposition Diamonds for Detector Applications

    International Nuclear Information System (INIS)

    Kagan, Harris; Gan, K.K.; Kass, Richard

    2009-01-01

    Diamond was studied as a possible radiation hard technology for use in future high radiation environments. With the commissioning of the LHC expected in 2009, and the LHC upgrades expected in 2013, all LHC experiments are planning for detector upgrades which require radiation hard technologies. Chemical Vapor Deposition (CVD) diamond has now been used extensively in beam conditions monitors as the innermost detectors in the highest radiation areas of BaBar, Belle and CDF and is installed in all LHC experiments. As a result, this material is now being discussed as an alternative sensor material for tracking very close to the interaction region of the super-LHC where the most extreme radiation conditions will exist. Our work addressed the further development of the new material, single-crystal Chemical Vapor Deposition diamond, towards reliable industrial production of large pieces and new geometries needed for detector applications.

  5. Communication: Surface-facilitated softening of ordinary and vapor-deposited glasses

    Science.gov (United States)

    Cubeta, Ulyana; Bhattacharya, Deepanjan; Sadtchenko, Vlad

    2017-08-01

    A common distinction between the ordinary glasses formed by melt cooling and the stable amorphous films formed by vapor deposition is the apparent mechanism of their devitrification. Using quasi-adiabatic, fast scanning calorimetry that is capable of heating rates in excess of 105 K s-1, we have investigated the softening kinetics of micrometer-scale, ordinary glass films of methylbenzene and 2-propanol. At the limit of high heating rates, the transformation mechanism of ordinary glasses is identical to that of their stable vapor-deposited counterparts. In both cases, softening is likely to begin at the sample surface and progress into its bulk via a transformation front. Furthermore, such a surface-facilitated mechanism complies with zero-order, Arrhenius rate law. The activation energy barriers for the softening transformation imply that the kinetics must be defined, at least in part, by the initial thermodynamic and structural state of the samples.

  6. Advanced Computational Modeling of Vapor Deposition in a High-Pressure Reactor

    Science.gov (United States)

    Cardelino, Beatriz H.; Moore, Craig E.; McCall, Sonya D.; Cardelino, Carlos A.; Dietz, Nikolaus; Bachmann, Klaus

    2004-01-01

    In search of novel approaches to produce new materials for electro-optic technologies, advances have been achieved in the development of computer models for vapor deposition reactors in space. Numerical simulations are invaluable tools for costly and difficult processes, such as those experiments designed for high pressures and microgravity conditions. Indium nitride is a candidate compound for high-speed laser and photo diodes for optical communication system, as well as for semiconductor lasers operating into the blue and ultraviolet regions. But InN and other nitride compounds exhibit large thermal decomposition at its optimum growth temperature. In addition, epitaxy at lower temperatures and subatmospheric pressures incorporates indium droplets into the InN films. However, surface stabilization data indicate that InN could be grown at 900 K in high nitrogen pressures, and microgravity could provide laminar flow conditions. Numerical models for chemical vapor deposition have been developed, coupling complex chemical kinetics with fluid dynamic properties.

  7. Atmospheric pressure chemical vapor deposition (APCVD) grown bi-layer graphene transistor characteristics at high temperature

    KAUST Repository

    Qaisi, Ramy M.

    2014-05-15

    We report the characteristics of atmospheric chemical vapor deposition grown bilayer graphene transistors fabricated on ultra-scaled (10 nm) high-κ dielectric aluminum oxide (Al2O3) at elevated temperatures. We observed that the drive current increased by >400% as temperature increased from room temperature to 250 °C. Low gate leakage was maintained for prolonged exposure at 100 °C but increased significantly at temperatures >200 °C. These results provide important insights for considering chemical vapor deposition graphene on aluminum oxide for high temperature applications where low power and high frequency operation are required. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Continuous growth of single-wall carbon nanotubes using chemical vapor deposition

    Science.gov (United States)

    Grigorian, Leonid [Raymond, OH; Hornyak, Louis [Evergreen, CO; Dillon, Anne C [Boulder, CO; Heben, Michael J [Denver, CO

    2008-10-07

    The invention relates to a chemical vapor deposition process for the continuous growth of a carbon single-wall nanotube where a carbon-containing gas composition is contacted with a porous membrane and decomposed in the presence of a catalyst to grow single-wall carbon nanotube material. A pressure differential exists across the porous membrane such that the pressure on one side of the membrane is less than that on the other side of the membrane. The single-wall carbon nanotube growth may occur predominately on the low-pressure side of the membrane or, in a different embodiment of the invention, may occur predominately in between the catalyst and the membrane. The invention also relates to an apparatus used with the carbon vapor deposition process.

  9. Metal organic chemical vapor deposition of 111-v compounds on silicon

    Science.gov (United States)

    Vernon, Stanley M.

    1986-01-01

    Expitaxial composite comprising thin films of a Group III-V compound semiconductor such as gallium arsenide (GaAs) or gallium aluminum arsenide (GaAlAs) on single crystal silicon substrates are disclosed. Also disclosed is a process for manufacturing, by chemical deposition from the vapor phase, epitaxial composites as above described, and to semiconductor devices based on such epitaxial composites. The composites have particular utility for use in making light sensitive solid state solar cells.

  10. Influence of Chemisorbed Oxygen on the Growth of Graphene on Cu(100) by Chemical Vapor Deposition

    OpenAIRE

    Robinson, Zachary R.; Ong, Eng Wen; Mowll, Tyler R.; Tyagi, Parul; Gaskill, D. Kurt; Geisler, Heike; Ventrice Jr, Carl A.

    2014-01-01

    Understanding the influence that copper substrate surface symmetry and oxygen impurities have on the growth of graphene by chemical vapor deposition is important for developing techniques for producing high quality graphene. Therefore, we have studied the growth of graphene by catalytic decomposition of ethylene in an ultra-high vacuum chamber on both a clean Cu(100) surface and a Cu(100) surface pre-dosed with a layer of chemisorbed oxygen. The crystal structure of the graphene films was cha...

  11. Continuous Ultra-Thin MOS2 Films Grown by Low-Temperature Physical Vapor Deposition (Postprint)

    Science.gov (United States)

    2014-07-01

    ultra-high vacuum physical vapor deposition process yields materials with key optical and electronic properties identical to exfoliated layers. The...process yields materials with key optical and electronic properties identical to exfoliated layers. The films are composed of nano-scale domains with...target. Throughout the pro- cess, the temperature was measured with an IR pyrometer calibrated with a thermocouple for each substrate material. The

  12. The transient creep of vapor deposited Ti-6Al-4V

    International Nuclear Information System (INIS)

    Warren, J.; Wadley, H.N.G.

    1996-01-01

    Titanium matrix composites can be synthesized by the consolidation of ceramic fibers (for example, alumina and silicon carbide monofilaments) coated with titanium alloy deposited on the fiber by physical vapor deposition (PVD). Consolidation involves deformation of the matrix coating by both transient and steady-state creep. In a recent paper the mechanisms responsible for steady-state creep in PVD Ti-6Al-4V, between 600 and 900 C, were determined. The analysis of the data first presented has been extended here to consider the transient creep behavior of the material and identify an analogous constitutive law for use in simulating the transient creep contribution to consolidation

  13. Photoluminescence in Chemical Vapor Deposited ZnS: insight into electronic defects

    Energy Technology Data Exchange (ETDEWEB)

    McCloy, John S.; Potter, B.g.

    2013-08-09

    Photoluminescence spectra taken from chemical vapor deposited (CVD) ZnS are shown to exhibit sub-band-gap emission bands characteristic of isoelectronic oxygen defects. The emission spectra vary spatially with position and orientation with respect to the major axis of CVD growth. These data suggest that a complex set of defects exist in the band gap of CVD ZnS whose structural nature is highly dependent upon local deposition and growth conditions, contributing to inherent heterogeneity in optical behavior throughout the material.

  14. Precise control of multiwall carbon nanotube diameters using thermal chemical vapor deposition

    Science.gov (United States)

    Siegal, M. P.; Overmyer, D. L.; Provencio, P. P.

    2002-03-01

    We grow multiwall carbon nanotube (CNT) films using thermal chemical vapor deposition at atmospheric pressure using a mixture of acetylene and nitrogen from a 4-nm-thick Ni film catalyst. CNTs are characterized using electron microscopy and Rutherford backscattering spectrometry. CNTs grown with this method are extremely uniform in diameter, both throughout the sample and within the lengths of individual tubes. Nanotube outer diameters, ranging from 5-350 nm, and the total deposition of carbon material, increase exponentially with growth temperature from 630 °C-790 °C.

  15. One-step microwave plasma enhanced chemical vapor deposition (MW-PECVD) for transparent superhydrophobic surface

    Science.gov (United States)

    Thongrom, Sukrit; Tirawanichakul, Yutthana; Munsit, Nantakan; Deangngam, Chalongrat

    2018-02-01

    We demonstrate a rapid and environmental friendly fabrication technique to produce optically clear superhydrophobic surfaces using poly (dimethylsiloxane) (PDMS) as a sole coating material. The inert PDMS chain is transformed into a 3-D irregular solid network through microwave plasma enhanced chemical vapor deposition (MW-PECVD) process. Thanks to high electron density in the microwave-activated plasma, coating can be done in just a single step with rapid deposition rate, typically much shorter than 10 s. Deposited layers show excellent superhydrophobic properties with water contact angles of ∼170° and roll-off angles as small as ∼3°. The plasma-deposited films can be ultrathin with thicknesses under 400 nm, greatly diminishing the optical loss. Moreover, with appropriate coating conditions, the coating layer can even enhance the transmission over the entire visible spectrum due to a partial anti-reflection effect.

  16. Patchy Janus particles with tunable roughness and composition via vapor-assisted deposition of macromolecules

    Science.gov (United States)

    Shepard, Kimberly B.; Christie, Dane A.; Sosa, Chris L.; Arnold, Craig B.; Priestley, Rodney D.

    2015-03-01

    Here, we present a technique for the fabrication of patchy Janus particles utilizing a vapor-assisted macromolecular deposition technique, termed Matrix Assisted Pulsed Laser Evaporation (MAPLE). Using this technique, both inorganic and organic precursor particles, immobilized on a surface, are functionalized on one hemisphere with nanodroplets of a desired polymer, thus forming particles with a patchy Janus morphology and textured surface topology. This fabrication method is flexible with respect to the chemical identity of the precursor particle and the selection of the deposited polymer. By tuning MAPLE deposition parameters, e.g., target composition or deposition time, the Janus anisotropy and roughness (i.e., patchiness) can be tuned, thus enabling greater control over the particles' behavior for applications as nanoparticle surfactants for stabilization of emulsions and foams.

  17. Metal organic chemical vapor deposition of environmental barrier coatings for the inhibition of solid deposit formation from heated jet fuel

    Science.gov (United States)

    Mohan, Arun Ram

    Solid deposit formation from jet fuel compromises the fuel handling system of an aviation turbine engine and increases the maintenance downtime of an aircraft. The deposit formation process depends upon the composition of the fuel, the nature of metal surfaces that come in contact with the heated fuel and the operating conditions of the engine. The objective of the study is to investigate the effect of substrate surfaces on the amount and nature of solid deposits in the intermediate regime where both autoxidation and pyrolysis play an important role in deposit formation. A particular focus has been directed to examining the effectiveness of barrier coatings produced by metal organic chemical vapor deposition (MOCVD) on metal surfaces for inhibiting the solid deposit formation from jet fuel degradation. In the first part of the experimental study, a commercial Jet-A sample was stressed in a flow reactor on seven different metal surfaces: AISI316, AISI 321, AISI 304, AISI 347, Inconel 600, Inconel 718, Inconel 750X and FecrAlloy. Examination of deposits by thermal and microscopic analysis shows that the solid deposit formation is influenced by the interaction of organosulfur compounds and autoxidation products with the metal surfaces. The nature of metal sulfides was predicted by Fe-Ni-S ternary phase diagram. Thermal stressing on uncoated surfaces produced coke deposits with varying degree of structural order. They are hydrogen-rich and structurally disordered deposits, spherulitic deposits, small carbon particles with relatively ordered structures and large platelets of ordered carbon structures formed by metal catalysis. In the second part of the study, environmental barrier coatings were deposited on tube surfaces to inhibit solid deposit formation from the heated fuel. A new CVD system was configured by the proper choice of components for mass flow, pressure and temperature control in the reactor. A bubbler was designed to deliver the precursor into the reactor

  18. Limitations of patterning thin films by shadow mask high vacuum chemical vapor deposition

    International Nuclear Information System (INIS)

    Reinke, Michael; Kuzminykh, Yury; Hoffmann, Patrik

    2014-01-01

    A key factor in engineering integrated devices such as electro-optic switches or waveguides is the patterning of high quality crystalline thin films into specific geometries. In this contribution high vacuum chemical vapor deposition (HV-CVD) was employed to grow titanium dioxide (TiO 2 ) patterns onto silicon. The directed nature of precursor transport – which originates from the high vacuum environment during the process – allows shading certain regions on the substrate by shadow masks and thus depositing patterned thin films. While the use of such masks is an emerging field in stencil or shadow mask lithography, their use for structuring thin films within HV-CVD has not been reported so far. The advantage of the employed technique is the precise control of lateral spacing and of the distance between shading mask and substrate surface which is achieved by manufacturing them directly on the substrate. As precursor transport takes place in the molecular flow regime, the precursor impinging rates (and therefore the film growth rates) on the surface can be simulated as function of the reactor and shading mask geometry using a comparatively simple mathematical model. In the current contribution such a mathematical model, which predicts impinging rates on plain or shadow mask structured substrates, is presented. Its validity is confirmed by TiO 2 -deposition on plain silicon substrates (450 °C) using titanium tetra isopropoxide as precursor. Limitations of the patterning process are investigated by the deposition of TiO 2 on structured substrates and subsequent shadow mask lift-off. The geometry of the deposits is according to the mathematical model. Shading effects due to the growing film enables to fabricate deposits with predetermined variations in topography and non-flat top deposits which are complicated to obtain by classical clean room processes. As a result of the enhanced residual pressure of decomposition products and titanium precursors and the

  19. An economic analysis of the deposition of electrochromic WO3 via sputtering or plasma enhanced chemical vapor deposition

    International Nuclear Information System (INIS)

    Garg, D.; Henderson, P.B.; Hollingsworth, R.E.; Jensen, D.G.

    2005-01-01

    The costs of manufacturing electrochromic WO 3 thin films deposited by either radio frequency plasma enhanced chemical vapor deposition (PECVD) or DC reactive magnetron sputtering of metal targets were modeled. Both inline systems for large area glass substrates and roll-to-roll systems for flexible webs were compared. Costs of capital, depreciation, raw materials, labor, power, and other miscellaneous items were accounted for in the model. The results predict that on similar sized systems, PECVD can produce electrochromic WO 3 for as little as one-third the cost, and have more than 10 times the annual production capacity of sputtering. While PECVD cost is dominated by raw materials, primarily WF 6 , sputtering cost is dominated by labor and depreciation

  20. Development of amorphous silicon based EUV hardmasks through physical vapor deposition

    Science.gov (United States)

    De Silva, Anuja; Mignot, Yann; Meli, Luciana; DeVries, Scott; Xu, Yongan; Seshadri, Indira; Felix, Nelson M.; Zeng, Wilson; Cao, Yong; Phan, Khoi; Dai, Huixiong; Ngai, Christopher S.; Stolfi, Michael; Diehl, Daniel L.

    2017-10-01

    Extending extreme ultraviolet (EUV) single exposure patterning to its limits requires more than photoresist development. The hardmask film is a key contributor in the patterning stack that offers opportunities to enhance lithographic process window, increase pattern transfer efficiency, and decrease defectivity when utilizing very thin film stacks. This paper introduces the development of amorphous silicon (a-Si) deposited through physical vapor deposited (PVD) as an alternative to a silicon ARC (SiARC) or silicon-oxide-type EUV hardmasks in a typical trilayer patterning scheme. PVD offers benefits such as lower deposition temperature, and higher purity, compared to conventional chemical vapor deposition (CVD) techniques. In this work, sub-36nm pitch line-space features were resolved with a positive-tone organic chemically-amplified resist directly patterned on PVD a-Si, without an adhesion promotion layer and without pattern collapse. Pattern transfer into the underlying hardmask stack was demonstrated, allowing an evaluation of patterning metrics related to resolution, pattern transfer fidelity, and film defectivity for PVD a-Si compared to a conventional tri-layer patterning scheme. Etch selectivity and the scalability of PVD a-Si to reduce the aspect ratio of the patterning stack will also be discussed.

  1. Flux and energy analysis of species in hollow cathode magnetron ionized physical vapor deposition of copper

    International Nuclear Information System (INIS)

    Wu, L.; Ko, E.; Dulkin, A.; Park, K. J.; Fields, S.; Leeser, K.; Meng, L.; Ruzic, D. N.

    2010-01-01

    To meet the stringent requirements of interconnect metallization for sub-32 nm technologies, an unprecedented level of flux and energy control of film forming species has become necessary to further advance ionized physical vapor deposition technology. Such technology development mandates improvements in methods to quantify the metal ion fraction, the gas/metal ion ratio, and the associated ion energies in the total ion flux to the substrate. In this work, a novel method combining planar Langmuir probes, quartz crystal microbalance (QCM), and gridded energy analyzer (GEA) custom instrumentation is developed to estimate the plasma density and temperature as well as to measure the metal ion fraction and ion energy. The measurements were conducted in a Novellus Systems, Inc. Hollow Cathode Magnetron (HCM TM ) physical vapor deposition source used for deposition of Cu seed layer for 65-130 nm technology nodes. The gridded energy analyzer was employed to measure ion flux and ion energy, which was compared to the collocated planar Langmuir probe data. The total ion-to-metal neutral ratio was determined by the QCM combined with GEA. The data collection technique and the corresponding analysis are discussed. The effect of concurrent resputtering during the deposition process on film thickness profile is also discussed.

  2. A predictive model for the chemical vapor deposition of polysilicon in a cold wall, rapid thermal system

    Energy Technology Data Exchange (ETDEWEB)

    Toprac, A.J.; Trachtenberg, I.; Edgar, T.F. (Univ. of Texas, Austin, TX (United States). Dept. of Chemical Engineering)

    1994-06-01

    The chemical vapor deposition of polysilicon from thermally activated silane in a cold wall, single-wafer rapid thermal system was studied by experimentation at a variety of low pressure conditions, including very high temperatures. The effect of diluent gas on polysilicon deposition rates was examined using hydrogen, helium, and krypton. A mass-transfer model for the chemical vapor deposition of polysilicon in a cold wall, rapid thermal system was developed. This model was used to produce an empirical rate expression for silicon deposition from silane by regressing kinetic parameters to fit experimental data. The resulting model provided accurate predictions over widely varying conditions in the experimental data.

  3. Plasma-enhanced chemical vapor deposition of graphene on copper substrates

    Directory of Open Access Journals (Sweden)

    Nicolas Woehrl

    2014-04-01

    Full Text Available A plasma enhanced vapor deposition process is used to synthesize graphene from a hydrogen/methane gas mixture on copper samples. The graphene samples were transferred onto SiO2 substrates and characterized by Raman spectroscopic mapping and atomic force microscope topographical mapping. Analysis of the Raman bands shows that the deposited graphene is clearly SLG and that the sheets are deposited on large areas of several mm2. The defect density in the graphene sheets is calculated using Raman measurements and the influence of the process pressure on the defect density is measured. Furthermore the origin of these defects is discussed with respect to the process parameters and hence the plasma environment.

  4. Heteroepitaxial diamond growth on 4H-SiC using microwave plasma chemical vapor deposition.

    Science.gov (United States)

    Moore, Eric; Jarrell, Joshua; Cao, Lei

    2017-09-01

    Deposition of heteroepitaxial diamond via microwave chemical vapor deposition has been performed on a 4H-SiC substrate using bias enhanced nucleation followed by a growth step. In future work, the diamond film will serve as a protective layer for an alpha particle sensor designed to function in an electrorefiner during pyroprocessing of spent fuel. The diamond deposition on the 4H-SiC substrate was carried out using a methane-hydrogen gas mixture with varying gas flow rates. The nucleation step was conducted for 30 minutes and provided sufficient nucleation sites to grow a diamond film on various locations on the substrate. The resulting diamond film was characterized using Raman spectroscopy exhibiting the strong Raman peak at 1332 cm -1 . Scanning electron microscopy was used to observe the surface morphology and the average grain size of the diamond film was observed to be on the order of ∼2-3 μm.

  5. Formation of graphene on BN substrate by vapor deposition method and size effects on its structure

    Science.gov (United States)

    Giang, Nguyen Hoang; Hanh, Tran Thi Thu; Ngoc, Le Nhu; Nga, Nguyen To; Van Hoang, Vo

    2018-04-01

    We report MD simulation of the growth of graphene by the vapor deposition on a two-dimensional hBN substrate. The systems (containing carbon vapor and hBN substrate) are relaxed at high temperature (1500 K), and then it is cooled down to room one (300 K). Carbon atoms interact with the substrate via the Lennard-Jones potential while the interaction between carbon atoms is computed via the Tersoff potential. Depending on the size of the model, different crystalline honeycomb structures have been found. Structural properties of the graphene obtained at 300 K are studied by analyzing radial distribution functions (RDFs), coordination numbers, ring statistics, interatomic distances, bond-angle distributions and 2D visualization of atomic configurations. We find that the models containing various numbers of atoms have a honeycomb structure. Besides, differences in structural properties of graphene formed by the vapor deposition on the substrate and free standing one are found. Moreover, the size effect on the structure is significant.

  6. Novel Prospects for Plasma Spray-Physical Vapor Deposition of Columnar Thermal Barrier Coatings

    Science.gov (United States)

    Anwaar, Aleem; Wei, Lianglinag; Guo, Qian; Zhang, Baopeng; Guo, Hongbo

    2017-12-01

    Plasma spray-physical vapor deposition (PS-PVD) is an emerging coating technique that can produce columnar thermal barrier coatings from vapor phase. Feedstock treatment at the start of its trajectory in the plasma torch nozzle is important for such vapor-phase deposition. This study describes the effects of the plasma composition (Ar/He) on the plasma characteristics, plasma-particle interaction, and particle dynamics at different points spatially distributed inside the plasma torch nozzle. The results of calculations show that increasing the fraction of argon in the plasma gas mixture enhances the momentum and heat flow between the plasma and injected feedstock. For the plasma gas combination of 45Ar/45He, the total enthalpy transferred to a representative powder particle inside the plasma torch nozzle is highest ( 9828 kJ/kg). Moreover, due to the properties of the plasma, the contribution of the cylindrical throat, i.e., from the feed injection point (FIP) to the start of divergence (SOD), to the total transferred energy is 69%. The carrier gas flow for different plasma gas mixtures was also investigated by optical emission spectroscopy (OES) measurements of zirconium emissions. Yttria-stabilized zirconia (YSZ) coating microstructures were produced when using selected plasma gas compositions and corresponding carrier gas flows; structural morphologies were found to be in good agreement with OES and theoretical predictions. Quasicolumnar microstructure was obtained with porosity of 15% when applying the plasma composition of 45Ar/45He.

  7. Deposition of silver nanoleaf film onto chemical vapor deposited diamond substrate and its application in surface-enhanced Raman scattering

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Jianwen [Laboratory of Organic Optoelectronic Functional Materials and Molecular Engineering, Technical Institute of Physics and Chemistry and Graduate University of Chinese Academy of Sciences, No. 2, Beiyitiao, Zhong-guan-cun, Haidian District, Beijing, 100080 (China); College of Chemistry and Chemical Engineering, Jishou University, Jishou, Hunan Province, 416000 (China); Tian Ruhai [Laboratory of Organic Optoelectronic Functional Materials and Molecular Engineering, Technical Institute of Physics and Chemistry and Graduate University of Chinese Academy of Sciences, No. 2, Beiyitiao, Zhong-guan-cun, Haidian District, Beijing, 100080 (China); Zhi Jinfang [Laboratory of Organic Optoelectronic Functional Materials and Molecular Engineering, Technical Institute of Physics and Chemistry and Graduate University of Chinese Academy of Sciences, No. 2, Beiyitiao, Zhong-guan-cun, Haidian District, Beijing, 100080 (China)], E-mail: zhi-mail@mail.ipc.ac.cn

    2008-04-30

    An approach for simultaneously synthesizing and immobilizing silver nanoleaves (SNLs) on {gamma}-mercaptopropyltrimethyoxysilane (MPTS)-modified chemical vapor deposited (CVD) diamond film surface has been developed. As-grown diamond film surface was oxidized by exposing to UV irradiation in oxygen gas atmosphere, and then the oxygen-terminated diamond film was dipped into a methanol solution of MPTS to form a self-assembled MPTS monolayer on the diamond film surface. SNLs were then deposited on diamond film surfaces by an electroless process. The morphology of SNL film was characterized by scanning electron microscopy. The thickness of SNL layer deposited onto the CVD diamond substrate increased with increasing the deposition time and the formation mechanism of SNL films was also discussed. Their performance as surface-enhanced Raman scattering (SERS) substrates was evaluated by using rhodamine 6G (R6G) as the probe molecule. Compared with self-assembled silver nanoparticle film and silver film from the mirror reaction, the SERS signal of R6G was obviously improved on the SNL films.

  8. Surface modification of reverse osmosis desalination membranes by thin-film coatings deposited by initiated chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Ozaydin-Ince, Gozde, E-mail: gozdeince@sabanciuniv.edu [Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Matin, Asif, E-mail: amatin@mit.edu [Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Khan, Zafarullah, E-mail: zukhan@mit.edu [Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Zaidi, S.M. Javaid, E-mail: zaidismj@kfupm.edu.sa [Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Gleason, Karen K., E-mail: kkgleasn@mit.edu [Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2013-07-31

    Thin-film polymeric reverse osmosis membranes, due to their high permeation rates and good salt rejection capabilities, are widely used for seawater desalination. However, these membranes are prone to biofouling, which affects their performance and efficiency. In this work, we report a method to modify the membrane surface without damaging the active layer or significantly affecting the performance of the membrane. Amphiphilic copolymer films of hydrophilic hydroxyethylmethacrylate and hydrophobic perfluorodecylacrylate (PFA) were synthesized and deposited on commercial RO membranes using an initiated chemical vapor deposition technique which is a polymer deposition technique that involves free-radical polymerization initiated by gas-phase radicals. Relevant surface characteristics such as hydrophilicity and roughness could be systematically controlled by varying the polymer chemistry. Increasing the hydrophobic PFA content in the films leads to an increase in the surface roughness and hydrophobicity. Furthermore, the surface morphology studies performed using the atomic force microscopy show that as the thickness of the coating increases average surface roughness increases. Using this knowledge, the coating thickness and chemistry were optimized to achieve high permeate flux and to reduce cell attachment. Results of the static bacterial adhesion tests show that the attachment of bacterial cells is significantly reduced on the coated membranes. - Highlights: • Thin films are deposited on reverse osmosis membranes. • Amphiphilic thin films are resistant to protein attachment. • The permeation performance of the membranes is not affected by the coating. • The thin film coatings delayed the biofouling.

  9. Deposition of titanium coating on SiC fiber by chemical vapor deposition with Ti-I{sub 2} system

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Xian, E-mail: luo_shenfan@hotmail.com; Wu, Shuai; Yang, Yan-qing; Jin, Na; Liu, Shuai; Huang, Bin

    2017-06-01

    Highlights: • The transformation paths of (Ti + I{sub 2}) powder to Ti coating is: Ti + I{sub 2} → (TiI{sub 2}, TiI{sub 3}) → Ti. • Uniform coating was obtained on SiC fiber, but it contained Si and C elements. • Deposition rate of the coating increased with the increase of temperature. • Deposition thickness increased with time and achieved the maximum at 90 min. - Abstract: Titanium coating was prepared on SiC fiber using titanium-iodine (Ti-I{sub 2}) mixture by hot-wall chemical vapor deposition. Thermodynamic analysis and experimental observation were carried out in this work. The thermodynamic analysis of the reactions in the Ti-I{sub 2} system indicates that Ti and I{sub 2} raw powder materials transform to titanium coating as follows: Ti + I{sub 2} → (TiI{sub 2}, TiI{sub 3}), and (TiI{sub 2}, TiI{sub 3}) → Ti. In theory, the conversions of TiI{sub 3} and TiI{sub 2} reach the maximum when Ti:I{sub 2} is 1:1.5, while in actual experiment that reached the maximum when Ti:I{sub 2} was 1:2, as there existed the waste of I{sub 2} due to sublimation. Typical deposited coating is relatively flat and uniform. However, as SiC is prone to react with Ti at high temperatures, the obtained coating contained some Si and C elements except for Ti. So the coating was not a pure Ti coating but contained some carbides and silicides. Deposition rate of the coating increased with the increase of temperature. The deposited thickness increased with the increase of heat preservation time, and achieved the maximum thickness at 90 min.

  10. Substrate Effect on Plasma Clean Efficiency in Plasma Enhanced Chemical Vapor Deposition System

    Directory of Open Access Journals (Sweden)

    Shiu-Ko JangJian

    2007-01-01

    Full Text Available The plasma clean in a plasma-enhanced chemical vapor deposition (PECVD system plays an important role to ensure the same chamber condition after numerous film depositions. The periodic and applicable plasma clean in deposition chamber also increases wafer yield due to less defect produced during the deposition process. In this study, the plasma clean rate (PCR of silicon oxide is investigated after the silicon nitride deposited on Cu and silicon oxide substrates by remote plasma system (RPS, respectively. The experimental results show that the PCR drastically decreases with Cu substrate compared to that with silicon oxide substrate after numerous silicon nitride depositions. To understand the substrate effect on PCR, the surface element analysis and bonding configuration are executed by X-ray photoelectron spectroscopy (XPS. The high resolution inductively coupled plasma mass spectrometer (HR-ICP-MS is used to analyze microelement of metal ions on the surface of shower head in the PECVD chamber. According to Cu substrate, the results show that micro Cu ion and the CuOx bonding can be detected on the surface of shower head. The Cu ion contamination might grab the fluorine radicals produced by NF3 ddissociation in the RPS and that induces the drastic decrease on PCR.

  11. Aerosol assisted chemical vapor deposition using nanoparticle precursors: a route to nanocomposite thin films.

    Science.gov (United States)

    Palgrave, Robert G; Parkin, Ivan P

    2006-02-08

    Gold nanoparticle and gold/semiconductor nanocomposite thin films have been deposited using aerosol assisted chemical vapor deposition (CVD). A preformed gold colloid in toluene was used as a precursor to deposit gold films onto silica glass. These nanoparticle films showed the characteristic plasmon absorption of Au nanoparticles at 537 nm, and scanning electron microscopic (SEM) imaging confirmed the presence of individual gold particles. Nanocomposite films were deposited from the colloid concurrently with conventional CVD precursors. A film of gold particles in a host tungsten oxide matrix resulted from co-deposition with [W(OPh)(6)], while gold particles in a host titania matrix resulted from co-deposition with [Ti(O(i)Pr)(4)]. The density of Au nanoparticles within the film could be varied by changing the Au colloid concentration in the original precursor solution. Titania/gold composite films were intensely colored and showed dichromism: blue in transmitted light and red in reflected light. They showed metal-like reflection spectra and plasmon absorption. X-ray photoelectron spectroscopy and energy-dispersive X-ray analysis confirmed the presence of metallic gold, and SEM imaging showed individual Au nanoparticles embedded in the films. X-ray diffraction detected crystalline gold in the composite films. This CVD technique can be readily extended to produce other nanocomposite films by varying the colloids and precursors used, and it offers a rapid, convenient route to nanoparticle and nanocomposite thin films.

  12. Magnetron target designs to improve wafer edge trench filling in ionized metal physical vapor deposition

    International Nuclear Information System (INIS)

    Lu Junqing; Yoon, Jae-Hong; Shin, Keesam; Park, Bong-Gyu; Yang Lin

    2006-01-01

    Severe asymmetry of the metal deposits on the trench sidewalls occurs near the wafer edge during low pressure ionized metal physical vapor deposition of Cu seed layer for microprocessor interconnects. To investigate this process and mitigate the asymmetry, an analytical view factor model based on the analogy between metal sputtering and diffuse thermal radiation was constructed. The model was validated based on the agreement between the model predictions and the reported experimental values for the asymmetric metal deposition at trench sidewalls near the wafer edge for a 200 mm wafer. This model could predict the thickness of the metal deposits across the wafer, the symmetry of the deposits on the trench sidewalls at any wafer location, and the angular distributions of the metal fluxes arriving at any wafer location. The model predictions for the 300 mm wafer indicate that as the target-to-wafer distance is shortened, the deposit thickness increases and the asymmetry decreases, however the overall uniformity decreases. Up to reasonable limits, increasing the target size and the sputtering intensity for the outer target portion significantly improves the uniformity across the wafer and the symmetry on the trench sidewalls near the wafer edge

  13. Controllable growth of nanostructured carbon from coal tar pitch by chemical vapor deposition

    International Nuclear Information System (INIS)

    Liu Xuguang; Yang Yongzhen; Ji Weiyun; Liu Hongyan; Zhang Chunyi; Xu Bingshe

    2007-01-01

    The direct synthesis of vapor grown carbon fibers with different diameters was achieved by the pyrolysis of coal tar pitch by chemical vapor deposition. The products were characterized by field-emission scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction and Raman spectroscopy. The experimental results demonstrated that ferrocene content, reaction temperature and Ar flow rate strongly influenced the yield and nature of nanostructured carbon materials, pure carbon microbeads, with diameter distribution ranging from 450 to 650 nm, were also obtained in the absence of catalyst, uniform and straight carbon nanofibers with the outer diameter of about 115 nm were obtained and curl and thick carbon fibers with narrow diameter distribution of 300-350 nm were produced

  14. Center for Beam Physics: 1994--95

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-05-01

    The Center for Beam Physics is a multidisciplinary research and development unit in the Accelerator and Fusion Research Division at the Lawrence Berkeley Laboratory of the University of California. At the heart of the Center`s mission is a fundamental quest for mechanisms of acceleration, radiation, transport, and focusing of energy and information. Dedicated to exploring the frontiers of particle and photon beam physics, its primary mission is to promote the science and technology of the production, manipulation, storage, and control of systems of charged particles and photons. This roster and annual report provides a glimpse of the scientists, engineers, technical support, students, and administrative staff that make up the CBP`s team and gives a brief review of the multifaceted activities during 1994 and 1995.

  15. Center for Beam Physics: 1994--95

    International Nuclear Information System (INIS)

    1995-05-01

    The Center for Beam Physics is a multidisciplinary research and development unit in the Accelerator and Fusion Research Division at the Lawrence Berkeley Laboratory of the University of California. At the heart of the Center's mission is a fundamental quest for mechanisms of acceleration, radiation, transport, and focusing of energy and information. Dedicated to exploring the frontiers of particle and photon beam physics, its primary mission is to promote the science and technology of the production, manipulation, storage, and control of systems of charged particles and photons. This roster and annual report provides a glimpse of the scientists, engineers, technical support, students, and administrative staff that make up the CBP's team and gives a brief review of the multifaceted activities during 1994 and 1995

  16. Fabrication and characterization of a cell electrostimulator device combining physical vapor deposition and laser ablation

    Science.gov (United States)

    Aragón, Angel L.; Pérez, Eliseo; Pazos, Antonio; Bao-Varela, Carmen; Nieto, Daniel

    2017-08-01

    In this work we present the process of fabrication and optimization of a prototype of a cell electrostimulator device for medical application combining physical vapor deposition and laser ablation. The fabrication of the first prototype begins with a deposition of a thin layer of 200 nm of aluminium on a borosilicate glass substrate using physical vapor deposition (PVD). In the second stage the geometry design of the electrostimulator is made in a CAD-like software available in a Nd:YVO4 Rofin Power line 20E, operating at the fundamental wavelength of 1064 nm and 20 ns pulse width. Choosing the proper laser parameters the negative of the electrostimulator desing is ablated. After that the glass is assembled between two polycarbonate sheets and a thick sheet of polydimethylsiloxane (PDMS). The PDMS sheet has a round hole in where cells are placed. There is also included a thin soda-lime silicate glass (100 μm) between the electrostimulator and the PMDS to prevent the cells for being in contact with the electric circuit. In order to control the electrical signal applied to the electrostimulator is used a digital I/O device from National Instruments (USB-6501) which provides 5 V at the output monitored by a software programmed in LabVIEW. Finally, the optical and electrical characterization of the cell electrostimulator device is presented.

  17. Reactive physical vapor deposition of TixAlyN: Integrated plasma-surface modeling characterization

    International Nuclear Information System (INIS)

    Zhang Da; Schaeffer, J.K.

    2004-01-01

    Reactive physical vapor deposition (RPVD) has been widely applied in the microelectronic industry for producing thin films. Fundamental understanding of RPVD mechanisms is needed for successful process development due to the high sensitivity of film properties on process conditions. An integrated plasma equipment-target nitridation modeling infrastructure for RPVD has therefore been developed to provide mechanistic insights and assist optimal process design. The target nitridation model computes target nitride coverage based on self-consistently derived plasma characteristics from the plasma equipment model; target sputter yields needed in the plasma equipment model are also self-consistently derived taking into account the yield-suppressing effect from nitridation. The integrated modeling infrastructure has been applied to investigating RPVD processing with a Ti 0.8 Al 0.2 compound target and an Ar/N 2 gas supply. It has been found that the process produces athermal metal neutrals as the primary deposition precursor. The metal stoichiometry in the deposited film is close to the target composition due to the predominance of athermal species in the flux that reaches the substrate. Correlations between process parameters (N 2 flow, target power), plasma characteristics, surface conditions, and deposition kinetics have been studied with the model. The deposition process is characterized by two regimes when the N 2 flow rate is varied. When N 2 is dilute relative to argon, target nitride coverage increases rapidly with increasing N 2 flow. The sputter yield and deposition rate consequently decrease. For less dilute N 2 mixtures, the sputter yield and deposition rate are stable due to the saturation of target nitridation. With increasing target power, the electron density increases nearly linearly while the variation of N generation is much smaller. Target nitridation and its suppression of the sputter yield saturate at high N 2 flow rendering these parameters

  18. Modeling and control of diffusion and low-pressure chemical vapor deposition furnaces

    Science.gov (United States)

    De Waard, H.; De Koning, W. L.

    1990-03-01

    In this paper a study is made of the heat transfer inside cylindrical resistance diffusion and low-pressure chemical vapor deposition furnaces, aimed at developing an improved temperature controller. A model of the thermal behavior is derived which also covers the important class of furnaces equipped with semitransparent quartz process tubes. The model takes into account the thermal behavior of the thermocouples. It is shown that currently used temperature controllers are highly inefficient for very large scale integration applications. Based on the model an alternative temperature controller of the linear-quadratic-Gaussian type is proposed which features direct wafer temperature control. Some simulation results are given.

  19. Chemical etching of copper foils for single-layer graphene growth by chemical vapor deposition

    Science.gov (United States)

    Yoshihara, Naoki; Noda, Masaru

    2017-10-01

    Chemical etching on copper surface is essential as a pre-treatment for single-layer graphene growth by chemical vapor deposition (CVD). Here, we investigated the effect of chemical etching treatment on copper foils for single-layer graphene CVD growth. The chemical etching conditions, such as the type of chemical etchants and the treatment time, were found to strongly influence the graphene domain size. Moreover, a drastic change in the layer structure of graphene sheets, which was attributed to the surface morphology of the etched copper foil, was confirmed by graphene transmittance and Raman mapping measurements.

  20. Electrical Characterization of Vapor-Deposited Single CdS Nanowire

    Science.gov (United States)

    Fu, X. L.; Tang, W. H.; Li, L. H.

    In this work, we synthesized chromium-doped CdS nanowires by simple vapor deposition. And the current-voltage characteristics of single CdS nanowire have been studied. The results from electrical transport measurements on the field-effect transistors showed that the nanowire was an n-type semiconductor. In addition, the Au/CdS nanowire device exhibited clear diode-like behavior, and a thermally-assisted tunneling mechanism, which dominates the transport of carriers above the metal-semiconductor contact in the diode, was discussed in detail.

  1. Growth of highly oriented carbon nanotubes by plasma-enhanced hot filament chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Z.P.; Xu, J.W.; Ren, Z.F.; Wang, J.H. [Materials Synthesis Laboratory, Departments of Physics and Chemistry, and Center for Advanced Photonic and Electronic Materials (CAPEM), State University of New York at Buffalo, Buffalo, New York 14260 (United States); Siegal, M.P.; Provencio, P.N. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1421 (United States)

    1998-12-01

    Highly oriented, multiwalled carbon nanotubes were grown on polished polycrystalline and single crystal nickel substrates by plasma enhanced hot filament chemical vapor deposition at temperatures below 666 {degree}C. The carbon nanotubes range from 10 to 500 nm in diameter and 0.1 to 50 {mu}m in length depending on growth conditions. Acetylene is used as the carbon source for the growth of the carbon nanotubes and ammonia is used for dilution gas and catalysis. The plasma intensity, acetylene to ammonia gas ratio, and their flow rates, etc. affect the diameters and uniformity of the carbon nanotubes. {copyright} {ital 1998 American Institute of Physics.}

  2. Time variant layer control in atmospheric pressure chemical vapor deposition based growth of graphene

    KAUST Repository

    Qaisi, Ramy M.

    2013-04-01

    Graphene is a semi-metallic, transparent, atomic crystal structure material which is promising for its high mobility, strength and transparency - potentially applicable for radio frequency (RF) circuitry and energy harvesting and storage applications. Uniform (same number of layers), continuous (not torn or discontinuous), large area (100 mm to 200 mm wafer scale), low-cost, reliable growth are the first hand challenges for its commercialization prospect. We show a time variant uniform (layer control) growth of bi- to multi-layer graphene using atmospheric chemical vapor deposition system. We use Raman spectroscopy for physical characterization supported by electrical property analysis. © 2013 IEEE.

  3. Vapor Phase Sensing Using Metal Nanorod Thin Films Grown by Cryogenic Oblique Angle Deposition

    Directory of Open Access Journals (Sweden)

    Piyush Shah

    2013-01-01

    Full Text Available We demonstrate the chemical sensing capability of silver nanostructured films grown by cryogenic oblique angle deposition (OAD. For comparison, the films are grown side by side at cryogenic (~100 K and at room temperature (~300 K by e-beam evaporation. Based on the observed structural differences, it was hypothesized that the cryogenic OAD silver films should show an increased surface enhanced Raman scattering (SERS sensitivity. COMSOL simulation results are presented to validate this hypothesis. Experimental SERS results of 4-aminobenzenethiol (4-ABT Raman test probe molecules in vapor phase show good agreement with the simulation and indicate promising SERS applications for these nanostructured thin films.

  4. Ultrasharp Si nanowires produced by plasma-enhanced chemical vapor deposition

    Czech Academy of Sciences Publication Activity Database

    Červenka, Jiří; Ledinský, Martin; Stuchlíková, The-Ha; Stuchlík, Jiří; Výborný, Zdeněk; Holovský, Jakub; Hruška, Karel; Fejfar, Antonín; Kočka, Jan

    2010-01-01

    Roč. 4, 1-2 (2010), s. 37-39 ISSN 1862-6254 R&D Projects: GA MŠk(CZ) LC06040; GA AV ČR KAN400100701; GA MŠk LC510 Institutional research plan: CEZ:AV0Z10100521 Keywords : nanowires * silicon * scanning electron microscopy * hemical vapor deposition * Raman spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.660, year: 2010 http://www3.interscience.wiley.com/cgi-bin/fulltext/123213957/HTMLSTART

  5. The structure and growth mechanism of Si nanoneedles prepared by plasma-enhanced chemical vapor deposition

    Czech Academy of Sciences Publication Activity Database

    Červenka, Jiří; Ledinský, Martin; Stuchlík, Jiří; Stuchlíková, The-Ha; Bakardjieva, Snejana; Hruška, Karel; Fejfar, Antonín; Kočka, Jan

    2010-01-01

    Roč. 21, č. 41 (2010), 415604/1-415604/7 ISSN 0957-4484 R&D Projects: GA MŠk(CZ) LC06040; GA AV ČR KAN400100701; GA MŠk LC510 EU Projects: European Commission(XE) 240826 - PolySiMode Institutional research plan: CEZ:AV0Z10100521; CEZ:AV0Z40320502 Keywords : nanoneedles * nanowires * silicon * plasma * chemical vapor deposition * crystal structure * growth * phonon * SEM * Raman Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.644, year: 2010

  6. An Investigation on the Formation of Carbon Nanotubes by Two-Stage Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    M. S. Shamsudin

    2012-01-01

    Full Text Available High density of carbon nanotubes (CNTs has been synthesized from agricultural hydrocarbon: camphor oil using a one-hour synthesis time and a titanium dioxide sol gel catalyst. The pyrolysis temperature is studied in the range of 700–900°C at increments of 50°C. The synthesis process is done using a custom-made two-stage catalytic chemical vapor deposition apparatus. The CNT characteristics are investigated by field emission scanning electron microscopy and micro-Raman spectroscopy. The experimental results showed that structural properties of CNT are highly dependent on pyrolysis temperature changes.

  7. MgB2 ultrathin films fabricated by hybrid physical chemical vapor deposition and ion milling

    Directory of Open Access Journals (Sweden)

    Narendra Acharya

    2016-08-01

    Full Text Available In this letter, we report on the structural and transport measurements of ultrathin MgB2 films grown by hybrid physical-chemical vapor deposition followed by low incident angle Ar ion milling. The ultrathin films as thin as 1.8 nm, or 6 unit cells, exhibit excellent superconducting properties such as high critical temperature (Tc and high critical current density (Jc. The results show the great potential of these ultrathin films for superconducting devices and present a possibility to explore superconductivity in MgB2 at the 2D limit.

  8. Influence of krypton atoms on the structure of hydrogenated amorphous carbon deposited by plasma enhanced chemical vapor deposition

    Science.gov (United States)

    Oliveira, M. H.; Viana, G. A.; de Lima, M. M.; Cros, A.; Cantarero, A.; Marques, F. C.

    2010-12-01

    Hydrogenated amorphous carbon (a-C:H) films were prepared by plasma enhanced chemical vapor deposition using methane (CH4) plus krypton (Kr) mixed atmosphere. The depositions were performed as function of the bias voltage and krypton partial pressure. The goal of this work was to study the influence of krypton gas on the physical properties of a-C:H films deposited on the cathode electrode. Krypton concentration up to 1.6 at. %, determined by Rutherford Back-Scattering, was obtained at high Kr partial pressure and bias of -120 V. The structure of the films was analyzed by means of optical transmission spectroscopy, multi-wavelength Raman scattering and Fourier Transform Infrared spectroscopy. It was verified that the structure of the films remains unchanged up to a concentration of Kr of about 1.0 at. %. A slight graphitization of the films occurs for higher concentration. The observed variation in the film structure, optical band gap, stress, and hydrogen concentration were associated mainly with the subplantation process of hydrocarbons radicals, rather than the krypton ion energy.

  9. Influence of krypton atoms on the structure of hydrogenated amorphous carbon deposited by plasma enhanced chemical vapor deposition

    International Nuclear Information System (INIS)

    Oliveira, M. H. Jr.; Viana, G. A.; Marques, F. C.; Lima, M. M. Jr. de; Cros, A.; Cantarero, A.

    2010-01-01

    Hydrogenated amorphous carbon (a-C:H) films were prepared by plasma enhanced chemical vapor deposition using methane (CH 4 ) plus krypton (Kr) mixed atmosphere. The depositions were performed as function of the bias voltage and krypton partial pressure. The goal of this work was to study the influence of krypton gas on the physical properties of a-C:H films deposited on the cathode electrode. Krypton concentration up to 1.6 at. %, determined by Rutherford Back-Scattering, was obtained at high Kr partial pressure and bias of -120 V. The structure of the films was analyzed by means of optical transmission spectroscopy, multi-wavelength Raman scattering and Fourier Transform Infrared spectroscopy. It was verified that the structure of the films remains unchanged up to a concentration of Kr of about 1.0 at. %. A slight graphitization of the films occurs for higher concentration. The observed variation in the film structure, optical band gap, stress, and hydrogen concentration were associated mainly with the subplantation process of hydrocarbons radicals, rather than the krypton ion energy.

  10. Two level undercut-profile substrate-based filamentary coated conductors produced using metal organic chemical vapor deposition

    DEFF Research Database (Denmark)

    Insinga, Andrea R.; Sundaram, Aarthi; Hazelton, Drew W.

    2018-01-01

    of a filamentary CC produced in an industrial setup by SuperPower Inc. using ion beam assisted deposition and metal organic chemical vapor deposition (IBAD-MOCVD) on a 2LUPS substrate realized at the Technical University of Denmark (DTU), whereas previous studies discussed the fabrication using alternating beam...

  11. A comparison of diamond growth rate using in-liquid and conventional plasma chemical vapor deposition methods

    International Nuclear Information System (INIS)

    Takahashi, Yoshiyuki; Toyota, Hiromichi; Nomura, Shinfuku; Mukasa, Shinobu; Inoue, Toru

    2009-01-01

    In order to make high-speed deposition of diamond effective, diamond growth rates for gas-phase microwave plasma chemical vapor deposition and in-liquid microwave plasma chemical vapor deposition are compared. A mixed gas of methane and hydrogen is used as the source gas for the gas-phase deposition, and a methanol solution of ethanol is used as the source liquid for the in-liquid deposition. The experimental system pressure is in the range of 60-150 kPa. While the growth rate of diamond increases as the pressure increases, the amount of input microwave energy per unit volume of diamond is 1 kW h/mm 3 regardless of the method used. Since the in-liquid deposition method provides a superior cooling effect through the evaporation of the liquid itself, a higher electric input power can be applied to the electrodes under higher pressure environments. The growth rate of in-liquid microwave plasma chemical vapor deposition process is found to be greater than conventional gas-phase microwave plasma chemical vapor deposition process under the same pressure conditions.

  12. A comparison of diamond growth rate using in-liquid and conventional plasma chemical vapor deposition methods

    Science.gov (United States)

    Takahashi, Yoshiyuki; Toyota, Hiromichi; Nomura, Shinfuku; Mukasa, Shinobu; Inoue, Toru

    2009-06-01

    In order to make high-speed deposition of diamond effective, diamond growth rates for gas-phase microwave plasma chemical vapor deposition and in-liquid microwave plasma chemical vapor deposition are compared. A mixed gas of methane and hydrogen is used as the source gas for the gas-phase deposition, and a methanol solution of ethanol is used as the source liquid for the in-liquid deposition. The experimental system pressure is in the range of 60-150 kPa. While the growth rate of diamond increases as the pressure increases, the amount of input microwave energy per unit volume of diamond is 1 kW h/mm3 regardless of the method used. Since the in-liquid deposition method provides a superior cooling effect through the evaporation of the liquid itself, a higher electric input power can be applied to the electrodes under higher pressure environments. The growth rate of in-liquid microwave plasma chemical vapor deposition process is found to be greater than conventional gas-phase microwave plasma chemical vapor deposition process under the same pressure conditions.

  13. Application of Chlorine-Assisted Chemical Vapor Deposition of Diamond at Low Temperatures

    Science.gov (United States)

    Pan, Chenyu; Altemir, David A.; Margrave, John L.; Hauge, Robert H.

    1994-01-01

    Low temperature deposition of diamond has been achieved by a chlorine-assisted diamond chemical vapor deposition (CA-CVD) process. This method begins with the thermal dissociation of molecular chlorine into atomic chlorine in a resistively heated graphite furnace at temperatures between 1300 and 1500 deg. C. The atomic chlorine, upon mixing, subsequently reacts with molecular hydrogen and hydrocarbons. The rapid exchange reactions between the atomic chlorine, molecular hydrogen, and hydrocarbons give rise to the atomic hydrogen and carbon precursors required for diamond deposition. Homoepitaxial diamond growth on diamond substrates has been studied over the substrate temperature range of 100-950 C. It was found that the diamond growth rates are approximately 0.2 microns/hr in the temperature range between 102 and 300 C and that the growth rates do not decrease significantly with a decrease in substrate temperature. This is unique because the traditional diamond deposition using H2/CH4 systems usually disappears at substrate temperatures below approx. 500 deg. C. This opens up a possible route to the deposition of diamond on low-melting point materials such as aluminum and its alloys.

  14. Ionized physical vapor deposition (IPVD): A review of technology and applications

    International Nuclear Information System (INIS)

    Helmersson, Ulf; Lattemann, Martina; Bohlmark, Johan; Ehiasarian, Arutiun P.; Gudmundsson, Jon Tomas

    2006-01-01

    In plasma-based deposition processing, the importance of low-energy ion bombardment during thin film growth can hardly be exaggerated. Ion bombardment is an important physical tool available to materials scientists in the design of new materials and new structures. Glow discharges and in particular, the magnetron sputtering discharge have the advantage that the ions of the discharge are abundantly available to the deposition process. However, the ion chemistry is usually dominated by the ions of the inert sputtering gas while ions of the sputtered material are rare. Over the last few years, various ionized sputtering techniques have appeared that can achieve a high degree of ionization of the sputtered atoms, often up to 50% but in some cases as much as approximately 90%. This opens a complete new perspective in the engineering and design of new thin film materials. The development and application of magnetron sputtering systems for ionized physical vapor deposition (IPVD) is reviewed. The application of a secondary discharge, inductively coupled plasma magnetron sputtering (ICP-MS) and microwave amplified magnetron sputtering, is discussed as well as the high power impulse magnetron sputtering (HIPIMS), the self-sustained sputtering (SSS) magnetron, and the hollow cathode magnetron (HCM) sputtering discharges. Furthermore, filtered arc-deposition is discussed due to its importance as an IPVD technique. Examples of the importance of the IPVD-techniques for growth of thin films with improved adhesion, improved microstructures, improved coverage of complex shaped substrates, and increased reactivity with higher deposition rate in reactive processes are reviewed

  15. Computer Simulation of Temperature Parameter for Diamond Formation by Using Hot-Filament Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    Chang Weon Song

    2017-12-01

    Full Text Available To optimize the deposition parameters of diamond films, the temperature, pressure, and distance between the filament and the susceptor need to be considered. However, it is difficult to precisely measure and predict the filament and susceptor temperature in relation to the applied power in a hot filament chemical vapor deposition (HF-CVD system. In this study, the temperature distribution inside the system was numerically calculated for the applied powers of 12, 14, 16, and 18 kW. The applied power needed to achieve the appropriate temperature at a constant pressure and other conditions was deduced, and applied to actual experimental depositions. The numerical simulation was conducted using the commercial computational fluent dynamics software ANSYS-FLUENT. To account for radiative heat-transfer in the HF-CVD reactor, the discrete ordinate (DO model was used. The temperatures of the filament surface and the susceptor at different power levels were predicted to be 2512–2802 K and 1076–1198 K, respectively. Based on the numerical calculations, experiments were performed. The simulated temperatures for the filament surface were in good agreement with the experimental temperatures measured using a two-color pyrometer. The results showed that the highest deposition rate and the lowest deposition of non-diamond was obtained at a power of 16 kW.

  16. High temperature dielectric properties of (BxNyOz thin films deposited using ion source assisted physical vapor deposition

    Directory of Open Access Journals (Sweden)

    N. Badi

    2015-12-01

    Full Text Available The dielectric integrity has been one of the major obstacle in bringing out capacitor devices with suitable performance characteristics at high temperatures. In this paper, BxNyOz dielectric films for high temperature capacitors solutions are investigated. The films were grown on silicon substrate by using ion source assisted physical vapor deposition technique. The as-grown films were characterized by SEM, XRD, and XPS. The capacitor structures were fabricated using BxNyOz as a dielectric and titanium as metal electrodes. The elaborated devices were subjected to electrical and thermal characterization. They exhibited low electrical loss and very good stability when subjected to high temperature for a prolonged period of time.

  17. Controlled density of vertically aligned carbon nanotubes in a triode plasma chemical vapor deposition system

    International Nuclear Information System (INIS)

    Lim, Sung Hoon; Park, Kyu Chang; Moon, Jong Hyun; Yoon, Hyun Sik; Pribat, Didier; Bonnassieux, Yvan; Jang, Jin

    2006-01-01

    We report on the growth mechanism and density control of vertically aligned carbon nanotubes using a triode plasma enhanced chemical vapor deposition system. The deposition reactor was designed in order to allow the intermediate mesh electrode to be biased independently from the ground and power electrodes. The CNTs grown with a mesh bias of + 300 V show a density of ∼ 1.5 μm -2 and a height of ∼ 5 μm. However, CNTs do not grow when the mesh electrode is biased to - 300 V. The growth of CNTs can be controlled by the mesh electrode bias which in turn controls the plasma density and ion flux on the sample

  18. Highly oriented, free-standing, superconducting NbN films growth on chemical vapor deposited graphene

    Directory of Open Access Journals (Sweden)

    Garima Saraswat

    2014-05-01

    Full Text Available NbN films are grown on chemical vapor deposited graphene using dc magnetron sputtering. The orientation and transition temperature of the deposited films is studied as a function of substrate temperature. A superconducting transition temperature of 14 K is obtained for highly oriented (111 films grown at substrate temperature of 150 °C, which is comparable to epitaxial films grown on MgO and sapphire substrates. These films show a considerably high upper critical field of ∼33 T. In addition, we demonstrate a process for obtaining flexible, free-standing NbN films by delaminating graphene from the substrate using a simple wet etching technique. These free-standing NbN layers can be transferred to any substrate, potentially enabling a range of novel superconducting thin-film applications.

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

    KAUST Repository

    Hussain, Aftab M.

    2013-08-16

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

  20. Surface modification of titanium membrane by chemical vapor deposition and its electrochemical self-cleaning

    International Nuclear Information System (INIS)

    Li, X.W.; Li, J.X.; Gao, C.Y.; Chang, M.

    2011-01-01

    Membrane separation is applied widely in many fields, while concentration polarization and membrane fouling, limiting its promotion and application greatly, are the bottlenecks in membrane application. Among which, membrane fouling is irreversible, membrane must be periodically cleaned or even replaced to restore permeability. Membrane cleaning has become one of Key issues in membrane separation areas. Considering incomparable electrochemical advantages of boron-doped diamond (BDD) film electrode over conventional electrode, a new composite membrane Ti/BDD, made by depositing CVD (chemical vapor deposition) boron-doped diamond film on titanium(Ti) membrane to modify porous titanium surface, that can be cleaned electrochemically is proposed. Feasibility of its preparation and application is discussed in this paper. Results shows that based on the unique electrochemical properties of diamond, cleaning level of this composite Ti/BDD membrane is significantly increased, making membrane life and efficiency improved prominently.

  1. Fabrication of thin-wall, freestanding inertial confinement fusion targets by chemical vapor deposition

    International Nuclear Information System (INIS)

    Carroll, D.W.; McCreary, W.J.

    1982-01-01

    To meet the requirements for plasma physics experiments in the inertial confinement fusion (ICF) program, chemical vapor deposition (CVD) in fluid beds was used to fabricate freestanding tungsten spheres and cylinders with wall thicknesses less than 5.0 μm. Molybdenum and molybdenum alloy (TZM) mandrels of the desired geometry were suspended in a carrier bed of dense microspheres contained in an induction-heated fluid-bed reactor. The mandrels were free to float randomly through the bed, and using the reaction WF 6 +3H 2 →/sub /KW +6HF, very fine-grained tungsten was deposited onto the surface at a rate and in a grain size determined by temperature, gas flow rate, system pressure, and duration of the reaction. After coating, a portion of each mandrel was exposed by hole drilling or grinding. The mandrel was then removed by acid leaching, leaving a freestanding tungsten shape. Experimental procedures, mandrel preparation, and results obtained are discussed

  2. Numerical evaluation of ABS parts fabricated by fused deposition modeling and vapor smoothing

    Directory of Open Access Journals (Sweden)

    Sung-Uk Zhang

    2017-12-01

    Full Text Available The automotive industry has focused to use polymer materials in order to increase energy efficiency. So, the industry pays attention to use 3D printing technologies using several polymers. Among several 3D printer technologies, fused deposition modeling (FDM is one of the popular 3D printing technologies due to an inexpensive extrusion machine and multi-material printing. FDM could use thermoplastics such as ABS, PLA, ULTEM so on. However, it has a problem related to the post-processing because FDM has relatively poor layer resolution. In this study, the mechanical properties of ABS parts fabricated by FDM were measured. The ABS parts were divided into one with vapor smoothing process and the other without the vapor smoothing process which is one of the post-processing methods. Using dynamic mechanical analysis (DMA and dilatometer, temperature-dependent storage modulus and CTE for ABS specimens were measured. Based on the measured thermo-mechanical properties of ABS parts, finite element analysis was performed for an automotive bumper made of ABS. Moreover, response surface methodology was applied to study relationships among design parameters of thickness of the bumper, ambient temperature, and application of the vapor smoothing process. In result, a design guideline for a ABS product could be provided without time-consuming experiments

  3. Low temperature atmospheric pressure chemical vapor deposition of group 14 oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, D.M. [Houston Univ., TX (United States); Atagi, L.M. [Houston Univ., TX (United States)]|[Los Alamos National Lab., NM (United States); Chu, Wei-Kan; Liu, Jia-Rui; Zheng, Zongshuang [Houston Univ., TX (United States); Rubiano, R.R. [Massachusetts Inst. of Tech., Cambridge, MA (United States); Springer, R.W.; Smith, D.C. [Los Alamos National Lab., NM (United States)

    1994-06-01

    Depositions of high quality SiO{sub 2} and SnO{sub 2} films from the reaction of homoleptic amido precursors M(NMe{sub 2})4 (M = Si,Sn) and oxygen were carried out in an atmospheric pressure chemical vapor deposition r. The films were deposited on silicon, glass and quartz substrates at temperatures of 250 to 450C. The silicon dioxide films are stoichiometric (O/Si = 2.0) with less than 0.2 atom % C and 0.3 atom % N and have hydrogen contents of 9 {plus_minus} 5 atom %. They are deposited with growth rates from 380 to 900 {angstrom}/min. The refractive indexes of the SiO{sub 2} films are 1.46, and infrared spectra show a possible Si-OH peak at 950 cm{sup {minus}1}. X-Ray diffraction studies reveal that the SiO{sub 2} film deposited at 350C is amorphous. The tin oxide films are stoichiometric (O/Sn = 2.0) and contain less than 0.8 atom % carbon, and 0.3 atom % N. No hydrogen was detected by elastic recoil spectroscopy. The band gap for the SnO{sub 2} films, as estimated from transmission spectra, is 3.9 eV. The resistivities of the tin oxide films are in the range 10{sup {minus}2} to 10{sup {minus}3} {Omega}cm and do not vary significantly with deposition temperature. The tin oxide film deposited at 350C is cassitterite with some (101) orientation.

  4. Chemical vapor deposition of amorphous tungsten nitride for applications in ultra-large scale interconnect technologies

    Science.gov (United States)

    Kelsey, Jean E.

    Increasing demands on computer chip technology require exploration of novel materials and deposition techniques. The driving need to reduce device dimensions without increasing device delay time has forced a move towards copper interconnects. Copper interconnects require an encapsulating barrier layer to prevent diffusion into the dielectric layer, as well as a passivation layer to protect against oxidation. One potential material for the barrier layer is tungsten nitride (WNx). Tungsten nitride is expected to perform well as a barrier because of its refractory nature and excellent thermal, chemical, and mechanical properties. In addition, it can be deposited in amorphous form. Amorphous materials have no grain boundaries, thereby making grain boundary diffusion, a fast path diffusion mechanism, impossible. In this work, a chemical vapor deposition (CVD) process was developed for the deposition of tungsten nitride. CVD was selected because it has the potential to deposit highly conformal film. High conformality is critical in a barrier layer in order to ensure viable coverage at the bottom and sides of device structures without sacrificing critical space that would be better used by the copper metal. In this manner, the total resistivity of the interconnect is minimized. The CVD WNx process was systematically optimized for film conformality, resistivity and growth rate. This was achieved by thoroughly examining film nucleation and growth characteristics, and analyzing resulting film properties. Adhesion of copper to the CVD films was qualified using stud pull tests, while X-ray diffraction was implemented to determine crystallization temperature of the amorphous phase. Additionally, diffusion barrier properties of the CVD tungsten nitride were assessed using sputter deposited copper, and compared to those of sputter deposited tungsten nitride. Thermally activated barrier failure was studied as a function of barrier thickness using Rutherford backscattering

  5. Transport in microcrystalline silicon thin films deposited at low temperature by hot-wire chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Bouree, Jean-Eric [Laboratoire de Physique des Interfaces et des Couches Minces, CNRS UMR 7647, Ecole Polytechnique, 91128 Palaiseau (France)]. E-mail: jean-eric.bouree@polytechnique.edu; Jadkar, Sandesh R. [School of Energy Studies, Department of Physics, University of Pune, Pune 411 007 (India); Kasouit, Samir [Laboratoire de Physique des Interfaces et des Couches Minces, CNRS UMR 7647, Ecole Polytechnique, 91128 Palaiseau (France); Vanderhaghen, Regis [Laboratoire de Physique des Interfaces et des Couches Minces, CNRS UMR 7647, Ecole Polytechnique, 91128 Palaiseau (France)

    2006-04-20

    This work is focused on the determination of the variation of local mobility of charge carriers with thickness (< 1 {mu}m) for undoped microcrystalline silicon layers deposited by the hot-wire chemical vapor deposition technique. We observed that the temperature of the layers T {sub s} evolves with the deposition time, once the tungsten filament has been heated from room temperature to a fixed definite value. Thus, experiments have been realized by fixing the gas pressure (41 mTorr), the dilution of silane in hydrogen (50%), by setting the filament temperature (1600 deg. C) and letting the time run. An average substrate temperature T {sub s,av} has been defined, whose value depends on deposition time. As a result, the local mobility deduced from time-resolved microwave conductivity increases almost linearly with T {sub s,av} up to 193 deg. C, i.e. with thickness up to 400 nm corresponding approximately to the amorphous-microcrystalline transition and then increases sublinearly up to T {sub s,av} = 221 deg. C, i.e. a 900-nm-thick layer. These results, compatible with the highest AM1.5 efficiency (> 9%) reported so far for p-i-n {mu}c-Si:H solar cells realized at T {sub s} = 185 deg. C [S. Klein, F. Finger, R. Carius, T. Dylla, B. Rech, M. Grimm, L. Houben, M. Stutzmann, Thin Solid Films 430 (2003) 202], suggest that in the range of T {sub s,av} from 190 deg. C to 220 deg. C, hydrogen plays a dominant role in the HWCVD growth of {mu}c-Si:H films.

  6. Understanding the reaction kinetics to optimize graphene growth on Cu by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kraus, Juergen; Boebel, Lena; Zwaschka, Gregor; Guenther, Sebastian [Technische Universitaet Muenchen, Zentralinstitut fuer Katalyseforschung, Chemie Department, Physikalische Chemie mit Schwerpunkt Katalyse, Garching (Germany)

    2017-11-15

    Understanding and controlling the growth kinetics of graphene is a prerequisite to synthesize this highly wanted material by chemical vapor deposition on Cu, e.g. for the construction of ultra-stable electron transparent membranes. It is reviewed that Cu foils contain a considerable amount of carbon in the bulk which significantly exceeds the expected amount of thermally equilibrated dissolved carbon in Cu and that this carbon must be removed before any high quality graphene may be grown. Starting with such conditioned Cu foils, systematic studies of the graphene growth kinetics in a reactive CH{sub 4}/H{sub 2} atmosphere allow to extract the following meaningful data: prediction of the equilibrium constant of the graphene formation reaction within a precision of a factor of two, the confirmation that the graphene growth proceeds from a C(ad)-phase on Cu which is in thermal equilibrium with the reactive gas phase, its apparent activation barrier and finally the prediction of the achievable growth velocity of the growing graphene flakes during chemical vapor deposition. As a result of the performed study, growth parameters are identified for the synthesis of high quality monolayer graphene with single crystalline domains of 100-1000 μm in diameter within a reasonable growth time. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Phase Equilibrium of TiO2 Nanocrystals in Flame-Assisted Chemical Vapor Deposition.

    Science.gov (United States)

    Liu, Changran; Camacho, Joaquin; Wang, Hai

    2018-01-19

    Nano-scale titanium oxide (TiO 2 ) is a material useful for a wide range of applications. In a previous study, we showed that TiO 2 nanoparticles of both rutile and anatase crystal phases could be synthesized over the size range of 5 to 20 nm in flame-assisted chemical vapor deposition. Rutile was unexpectedly dominant in oxygen-lean synthesis conditions, whereas anatase is the preferred phase in oxygen-rich gases. The observation is in contrast to the 14 nm rutile-anatase crossover size derived from the existing crystal-phase equilibrium model. In the present work, we made additional measurements over a wider range of synthesis conditions; the results confirm the earlier observations. We propose an improved model for the surface energy that considers the role of oxygen desorption at high temperatures. The model successfully explains the observations made in the current and previous work. The current results provide a useful path to designing flame-assisted chemical vapor deposition of TiO 2 nanocrystals with controllable crystal phases. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. PROPERTIES AND OPTICAL APPLICATION OF POLYCRYSTALLINE ZINC SELENIDE OBTAINED BY PHYSICAL VAPOR DEPOSITION

    Directory of Open Access Journals (Sweden)

    A. A. Dunaev

    2015-05-01

    Full Text Available Findings on production technology, mechanical and optical properties of polycrystalline zinc selenide are presented. The combination of its physicochemical properties provides wide application of ZnSe in IR optics. Production technology is based on the method of physical vapor deposition on a heated substrate (Physical Vapor Deposition - PVD. The structural features and heterogeneity of elemental composition for the growth surfaces of ZnSe polycrystalline blanks were investigated using CAMEBAX X-ray micro-analyzer. Characteristic pyramid-shaped crystallites were recorded for all growth surfaces. The measurements of the ratio for major elements concentrations show their compliance with the stoichiometry of the ZnSe compounds. Birefringence, optical homogeneity, thermal conductivity, mechanical and optical properties were measured. It is established that regardless of polycrystalline condensate columnar and texturing, the optical material is photomechanically isotropic and homogeneous. The actual performance of parts made of polycrystalline optical zinc selenide in the thermal spectral ranges from 3 to 5 μm and from 8 to 14 μm and in the CO2 laser processing plants with a power density of 500 W/cm2 is shown. The developed technology gives the possibility to produce polycrystalline optical material on an industrial scale.

  9. Plasma-enhanced chemical vapor deposition of silicon oxynitride for micromachined millimeter-wave devices

    Science.gov (United States)

    Saadaoui, M.; Peyrou, D.; Achkar, H.; Pennec, F.; Bouscayrol, L.; Rousset, B.; Boyer, P. T.; Scheid, E.; Pons, P.; Plana, R.

    2008-03-01

    Silicon oxynitride films were deposited by plasma-enhanced chemical vapor deposition at low temperature and frequency using SiH4 + NH3 + N2O gas mixtures. The process is optimized in order to deposit film with low tensile stress and high resistance during KOH etching. By increasing the gas flow of nitrous oxide (N2O), the film tends to be oxygen rich and the usual as-deposited high compressive stress is reduced to its lowest state at O/Si = 0.74. Annealing films above 480 °C generates low tensile stress suitable for membrane fabrication, and further infrared spectroscopy analysis shows that the shrinking of Si-O and Si-N bonds seems to be the cause of reversing the stress's nature. Young's modulus of the optimized layer is characterized by indentation. In application, 75 Ω coplanar waveguides (CPW) were fabricated on the top of an oxynitride membrane and characterized in term of insertion loss and effective permittivity. The results were compared to those obtained with the well-controlled bilayer silicon oxide-nitride membrane technology. The obtained losses are lower than 0.2 dB at 30 GHz with a free-space propagation signal.

  10. Development of plasma assisted thermal vapor deposition technique for high-quality thin film

    Science.gov (United States)

    Lee, Kang-Il; Choi, Yong Sup; Park, Hyun Jae

    2016-12-01

    The novel technique of Plasma-Assisted Vapor Deposition (PAVD) is developed as a new deposition method for thin metal films. The PAVD technique yields a high-quality thin film without any heating of the substrate because evaporated particles acquire energy from plasma that is confined to the inside of the evaporation source. Experiments of silver thin film deposition have been carried out in conditions of pressure lower than 10-3 Pa. Pure silver plasma generation is verified by the measurement of the Ag-I peak using optical emission spectroscopy. A four point probe and a UV-VIS spectrophotometer are used to measure the electrical and optical properties of the silver film that is deposited by PAVD. For an ultra-thin silver film with a thickness of 6.5 nm, we obtain the result of high-performance silver film properties, including a sheet resistance visible-range transmittance >75%. The PAVD-film properties show a low sheet resistance of 30% and the same transmittance with conventional thermal evaporation film. In the PAVD source, highly energetic particles and UV from plasma do not reach the substrate because the plasma is completely shielded by the optimized nozzle of the crucible. This new PAVD technique could be a realistic solution to improve the qualities of transparent electrodes for organic light emission device fabrication without causing damage to the organic layers.

  11. Nucleation and growth of microdroplets of ionic liquids deposited by physical vapor method onto different surfaces

    Science.gov (United States)

    Costa, José C. S.; Coelho, Ana F. S. M. G.; Mendes, Adélio; Santos, Luís M. N. B. F.

    2018-01-01

    Nanoscience and technology has generated an important area of research in the field of properties and functionality of ionic liquids (ILs) based materials and their thin films. This work explores the deposition process of ILs droplets as precursors for the fabrication of thin films, by means of physical vapor deposition (PVD). It was found that the deposition (by PVD on glass, indium tin oxide, graphene/nickel and gold-coated quartz crystal surfaces) of imidazolium [C4mim][NTf2] and pyrrolidinium [C4C1Pyrr][NTf2] based ILs generates micro/nanodroplets with a shape, size distribution and surface coverage that could be controlled by the evaporation flow rate and deposition time. No indication of the formation of a wetting-layer prior to the island growth was found. Based on the time-dependent morphological analysis of the micro/nanodroplets, a simple model for the description of the nucleation process and growth of ILs droplets is presented. The proposed model is based on three main steps: minimum free area to promote nucleation; first order coalescence; second order coalescence.

  12. Multiscale Modeling of Chemical Vapor Deposition (CVD Apparatus: Simulations and Approximations

    Directory of Open Access Journals (Sweden)

    Juergen Geiser

    2013-02-01

    Full Text Available We are motivated to compute delicate chemical vapor deposition (CVD processes. Such processes are used to deposit thin films of metallic or ceramic materials, such as SiC or a mixture of SiC and TiC. For practical simulations and for studying the characteristics in the deposition area, we have to deal with delicate multiscale models. We propose a multiscale model based on two different software packages. The large scales are simulated with computational fluid dynamics (CFD software based on the transportreaction model (or macroscopic model, and the small scales are simulated with ordinary differential equations (ODE software based on the reactive precursor gas model (or microscopic model. Our contribution is to upscale the correlation of the underlying microscale species to the macroscopic model and reformulate the fast reaction model. We obtain a computable model and apply a standard CFD software code without losing the information of the fast processes. For the multiscale model, we present numerical results of a real-life deposition process.

  13. 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.

  14. Study of the fluidized bed chemical vapor deposition process on very dense powder for nuclear applications

    International Nuclear Information System (INIS)

    Vanni, Florence

    2015-01-01

    This thesis is part of the development of low-enriched nuclear fuel, for the Materials Test Reactors (MTRs), constituted of uranium-molybdenum particles mixed with an aluminum matrix. Under certain conditions under irradiations, the U(Mo) particles interact with the aluminum matrix, causing unacceptable swelling of the fuel plate. To inhibit this phenomenon, one solution consists in depositing on the surface of the U(Mo) particles, a thin silicon layer to create a barrier effect. This thesis has concerned the study of the fluidized bed chemical vapor deposition (CVD) process to deposit silicon from silane, on the U(Mo) powder, which has an exceptional density of 17,500 kg/m 3 . To achieve this goal, two axes were treated during the thesis: the study and the optimization of the fluidization of a so dense powder, and then those of the silicon deposition process. For the first axis, a series of tests was performed on a surrogate tungsten powder in different columns made of glass and made of steel with internal diameters ranging from 2 to 5 cm, at room temperature and at high temperature (650 C) close to that of the deposits. These experiments helped to identify wall effects phenomena within the fluidized bed, which can lead to heterogeneous deposits or particles agglomeration. Some dimensions of the fluidization columns and operating conditions allowing a satisfactory fluidization of the powder were identified, paving the way for the study of silicon deposition. Several campaigns of deposition experiments on the surrogate powder and then on the U(Mo) powder were carried out in the second axis of the study. The influence of the bed temperature, the inlet molar fraction of silane diluted in argon, and the total gas flow of fluidization, was examined for different diameters of reactor and for various masses of powder. Morphological and structural characterization analyses (SEM, XRD..) revealed a uniform silicon deposition on all the powder and around each particle

  15. Phosphorus atomic layer doping in SiGe using reduced pressure chemical vapor deposition

    International Nuclear Information System (INIS)

    Yamamoto, Yuji; Heinemann, Bernd; Murota, Junichi; Tillack, Bernd

    2014-01-01

    Phosphorus (P) atomic layer doping in SiGe is investigated at temperatures between 100 °C to 600 °C using a single wafer reduced pressure chemical vapor deposition system. SiGe(100) surface is exposed to PH 3 at different PH 3 partial pressures by interrupting SiGe growth. The impact of the SiGe buffer/cap growth condition (total pressure/SiGe deposition precursors) on P adsorption, incorporation, and segregation are investigated. In the case of SiH 4 -GeH 4 -H 2 gas system, steeper P spikes due to lower segregation are observed by SiGe cap deposition at atmospheric (ATM) pressure compared with reduced pressure (RP). The steepness of P spike of ∼ 5.7 nm/dec is obtained for ATM pressure without reducing deposition temperature. This result may be due to the shift of equilibrium of P adsorption/desorption to desorption direction by higher H 2 pressure. Using Si 2 H 6 -GeH 4 -H 2 gas system for SiGe cap deposition in RP, lowering the SiGe growth temperature is possible, resulting in higher P incorporation and steeper P profile due to reduced desorption and segregation. In the case of Si 2 H 6 -GeH 4 -H 2 gas system, the P dose could be simulated assuming a Langmuir-type kinetics model. Incorporated P shows high electrical activity, indicating P is adsorbed mostly in lattice position. - Highlights: • Phosphorus (P) atomic layer doping in SiGe (100) is investigated using CVD. • P adsorption is suppressed by the hydrogen termination of Ge surface. • By SiGe cap deposition at atmospheric pressure, P segregation was suppressed. • By using Si 2 H 6 -based SiGe cap, P segregation was also suppressed. • The P adsorption process is self-limited and follows Langmuir-type kinetics model

  16. Magmatic-vapor expansion and the formation of high-sulfidation gold deposits: Chemical controls on alteration and mineralization

    Science.gov (United States)

    Henley, R.W.; Berger, B.R.

    2011-01-01

    Large bulk-tonnage high-sulfidation gold deposits, such as Yanacocha, Peru, are the surface expression of structurally-controlled lode gold deposits, such as El Indio, Chile. Both formed in active andesite-dacite volcanic terranes. Fluid inclusion, stable isotope and geologic data show that lode deposits formed within 1500. m of the paleo-surface as a consequence of the expansion of low-salinity, low-density magmatic vapor with very limited, if any, groundwater mixing. They are characterized by an initial 'Sulfate' Stage of advanced argillic wallrock alteration ?? alunite commonly with intense silicification followed by a 'Sulfide' Stage - a succession of discrete sulfide-sulfosalt veins that may be ore grade in gold and silver. Fluid inclusions in quartz formed during wallrock alteration have homogenization temperatures between 100 and over 500 ??C and preserve a record of a vapor-rich environment. Recent data for El Indio and similar deposits show that at the commencement of the Sulfide Stage, 'condensation' of Cu-As-S sulfosalt melts with trace concentrations of Sb, Te, Bi, Ag and Au occurred at > 600 ??C following pyrite deposition. Euhedral quartz crystals were simultaneously deposited from the vapor phase during crystallization of the vapor-saturated melt occurs to Fe-tennantite with progressive non-equilibrium fractionation of heavy metals between melt-vapor and solid. Vugs containing a range of sulfides, sulfosalts and gold record the changing composition of the vapor. Published fluid inclusion and mineralogical data are reviewed in the context of geological relationships to establish boundary conditions through which to trace the expansion of magmatic vapor from source to surface and consequent alteration and mineralization. Initially heat loss from the vapor is high resulting in the formation of acid condensate permeating through the wallrock. This Sulfate Stage alteration effectively isolates the expansion of magmatic vapor in subsurface fracture arrays

  17. Industrialization of Hot Wire Chemical Vapor Deposition for thin film applications

    International Nuclear Information System (INIS)

    Schropp, R.E.I.

    2015-01-01

    The consequences of implementing a Hot Wire Chemical Vapor Deposition (HWCVD) chamber into an existing in-line or roll-to-roll reactor are described. The hardware and operation of the HWCVD production reactor is compared to that of existing roll-to-roll reactors based on Plasma Enhanced Chemical Vapor Deposition. The most important consequences are the technical consequences and the economic consequences, which are both discussed. The technical consequences are adaptations needed to the hardware and to the processing sequences due to the different interaction of the HWCVD process with the substrate and already deposited layers. The economic consequences are the reduced investments in radio frequency (RF) supplies and RF components. This is partially offset by investments that have to be made in higher capacity pumping systems. The most mature applications of HWCVD are moisture barrier coatings for thin film flexible devices such as Organic Light Emitting Diodes and Organic Photovoltaics, and passivation layers for multicrystalline Si solar cells, high mobility field effect transistors, and silicon heterojunction cells (also known as heterojunction cells with intrinsic thin film layers). Another example is the use of Si in thin film photovoltaics. The cost perspective per unit of thin film photovoltaic product using HWCVD is estimated at 0.07 €/Wp for the Si thin film component. - Highlights: • Review of consequences of implementing Hot Wire CVD into a manufacturing plant • Aspects of scaling up to large area and continuous manufacturing are discussed • Economic advantage of introducing a HWCVD process in a production system is estimated • Using HWCVD, the cost for the Si layers in photovoltaic products is 0.08 €/Wp.

  18. Chemical vapor deposition of refractory ternary nitrides for advanced diffusion barriers

    Energy Technology Data Exchange (ETDEWEB)

    Custer, Jonathan S.; Fleming, James G.; Roherty-Osmun, Elizabeth; Smith, Paul Martin

    1998-09-22

    Refractory ternary nitride films for diffusion barriers in microelectronics have been grown using chemical vapor deposition. Thin films of titanium-silicon-nitride, tungsten-boron-nitride, and tungsten-silicon-nitride of various compositions have been deposited on 150 mm Si wafers. The microstructure of the films are either fully amorphous for the tungsten based films, or nauocrystalline TiN in an amorphous matrix for titanium-silicon-nitride. All films exhibit step coverages suitable for use in future microelectronics generations. Selected films have been tested as diffusion barriers between copper and silicon, and generally perform extremely weH. These fiIms are promising candidates for advanced diffusion barriers for microelectronics applications. The manufacturing of silicon wafers into integrated circuits uses many different process and materials. The manufacturing process is usually divided into two parts: the front end of line (FEOL) and the back end of line (BEOL). In the FEOL the individual transistors that are the heart of an integrated circuit are made on the silicon wafer. The responsibility of the BEOL is to wire all the transistors together to make a complete circuit. The transistors are fabricated in the silicon itself. The wiring is made out of metal, currently aluminum and tungsten, insulated by silicon dioxide, see Figure 1. Unfortunately, silicon will diffuse into aluminum, causing aluminum spiking of junctions, killing transistors. Similarly, during chemical vapor deposition (CVD) of tungsten from ~fj, the reactivity of the fluorine can cause "worn-holes" in the silicon, also destroying transistors. The solution to these problems is a so-called diffusion barrier, which will allow current to pass from the transistors to the wiring, but will prevent reactions between silicon and the metal.

  19. Phase diagram of interfacial growth modes by vapor deposition and its application for ZnO nanostructures

    Science.gov (United States)

    Shu, Da-Jun; Xiong, Xiang; Liu, Ming; Wang, Mu

    2017-09-01

    Interfacial growth from vapor has been extensively studied. However, a straightforward picture of the growth mode under different growth conditions is still lacking. In this paper, we develop a comprehensive interfacial growth theory based on the stochastic approach. Using a critical interisland separation, we construct a general phase diagram of the growth modes. It has been revealed that if the Ehrlich-Schwoebel barrier EES is smaller than a critical value, the interfacial growth proceeds in a layer-by-layer (LBL) mode at any deposition rate. However, if EES is larger than the critical value, LBL growth occurs only at very small or very large deposition rates relative to the intralayer hopping rate, and multilayer (ML) growth occurs at a moderate deposition rate. Experiments with zinc oxide growth by chemical vapor deposition have been designed to qualitatively demonstrate the theoretical model. By changing the flux of the carrier gas (nitrogen gas) in chemical vapor deposition, we realize LBL, ML, and then reentrance of LBL homoepitaxial growth of ZnO successively. Moreover, we find that surface kinetics of ZnO is suppressed by decreasing oxygen partial pressure by comparing the experimental observations and theoretical models, which is supported by our recent first-principles calculations. Since the influence of the substrate and the growth species on growth can approximately be represented by binding energy and surface kinetics, we suggest that the phase diagram is essential for interfacial growth of different materials by vapor deposition.

  20. Center for beam physics 1996-1997

    International Nuclear Information System (INIS)

    1997-02-01

    The Center for Beam Physics (CBP) is a multidisciplinary research and development unit in the Accelerator and Fusion Research Division at the Ernest Orlando Lawrence Berkeley National Laboratory of the University of California. At the heart of the Center's mission is the fundamental quest for mechanisms of acceleration, radiation, transport, and focusing of energy and information. Special features of the Center's program include addressing R ampersand D issues needing long development time and providing a platform for conception, initiation, and support of institutional projects based on beams. The Center brings to bear a significant amount of diverse, complementary, and self-sufficient expertise in accelerator physics, synchrotron radiation, advanced microwave techniques, plasma physics, optics, and lasers on the forefront R ampersand D issues in particle and photon beam research. In addition to functioning as a clearinghouse for novel ideas and concepts and related R ampersand D (e.g., various theoretical and experimental studies in beam physics such as nonlinear dynamics, phase space control, laser-beam-plasma interaction, free-electron lasers, optics, and instrumentation), the Center provides significant support to Laboratory facilities and initiatives. This roster and annual report provides a glimpse of the scientists, engineers, technical support, students, and administrative staff that make up the CBP's outstanding team and gives a flavor of their multifaceted activities during 1996 and 1997

  1. Center for beam physics 1996-1997

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-02-01

    The Center for Beam Physics (CBP) is a multidisciplinary research and development unit in the Accelerator and Fusion Research Division at the Ernest Orlando Lawrence Berkeley National Laboratory of the University of California. At the heart of the Center`s mission is the fundamental quest for mechanisms of acceleration, radiation, transport, and focusing of energy and information. Special features of the Center`s program include addressing R&D issues needing long development time and providing a platform for conception, initiation, and support of institutional projects based on beams. The Center brings to bear a significant amount of diverse, complementary, and self-sufficient expertise in accelerator physics, synchrotron radiation, advanced microwave techniques, plasma physics, optics, and lasers on the forefront R&D issues in particle and photon beam research. In addition to functioning as a clearinghouse for novel ideas and concepts and related R&D (e.g., various theoretical and experimental studies in beam physics such as nonlinear dynamics, phase space control, laser-beam-plasma interaction, free-electron lasers, optics, and instrumentation), the Center provides significant support to Laboratory facilities and initiatives. This roster and annual report provides a glimpse of the scientists, engineers, technical support, students, and administrative staff that make up the CBP`s outstanding team and gives a flavor of their multifaceted activities during 1996 and 1997.

  2. Epitaxial Oxide Thin Films Grown by Solid Source Metal-Organic Chemical Vapor Deposition.

    Science.gov (United States)

    Lu, Zihong

    1995-01-01

    The conventional liquid source metal-organic chemical vapor deposition (MOCVD) technique is capable of producing large area, high quality, single crystal semiconductor films. However, the growth of complex oxide films by this method has been hampered by a lack of suitable source materials. While chemists have been actively searching for new source materials, the research work reported here has demonstrated the successful application of solid metal-organic sources (based on tetramethylheptanedionate) to the growth of high quality thin films of binary compound cerium dioxide (CeO_2), and two more complex materials, the ternary compound lithium niobate (LiNbO_3), with two cations, and the quaternary compound strontium barium niobate (SBN), with three cations. The growth of CeO_2 thin films on (1012)Al_2O_3 substrates has been used as a model to study the general growth behavior of oxides. Factors affecting deposition rate, surface morphology, out-of-plane mosaic structure, and film orientation have been carefully investigated. A kinetic model based on gas phase prereaction is proposed to account for the substrate temperature dependence of film orientation found in this system. Atomically smooth, single crystal quality cerium dioxide thin films have been obtained. Superconducting YBCO films sputtered on top of solid source MOCVD grown thin cerium dioxide buffer layers on sapphire have been shown to have physical properties as good as those of YBCO films grown on single crystal MgO substrates. The thin film growth of LiNbO_3 and Sr_{1-x}Ba _{x}Nb_2 O_6 (SBN) was more complex and challenging. Phase purity, transparency, in-plane orientation, and the ferroelectric polarity of LiNbO _3 films grown on sapphire substrates was investigated. The first optical quality, MOCVD grown LiNbO _3 films, having waveguiding losses of less than 2 dB/cm, were prepared. An important aspect of the SBN film growth studies involved finding a suitable single crystal substrate material. Mg

  3. Formation of vanadium oxides with various morphologies by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Su, Q.; Huang, C.K.; Wang, Y.; Fan, Y.C.; Lu, B.A.; Lan, W.; Wang, Y.Y. [Department of Physics, Lanzhou University, Lanzhou 730000 (China); Liu, X.Q. [Department of Physics, Lanzhou University, Lanzhou 730000 (China)], E-mail: xqliu@lzu.edu.cn

    2009-05-05

    We reported the formation of vanadium oxides with various morphologies, including V{sub 2}O{sub 5} rods, VO{sub x} microspheres, VO{sub 2} microblocks etc., by chemical vapor deposition using vanadyl acetylacetonate (VO(acac){sub 2}) powder as a vanadium precursor. The obtained samples were characterized by scanning electron microscopy (SEM), Raman scattering and X-ray diffraction (XRD). Results revealed that the morphologies and microstructures of vanadium oxides were significantly dependent on the depositing temperature. V{sub 2}O{sub 5} rods with a diameter of {approx}250 nm, VO{sub x} microstructure with V{sup 5+} and V{sup 4+} cations and VO{sub 2} microblocks were obtained at the depositing temperature of 500, 450-250 and 150 deg. C, respectively. VO{sub 2} structures were formed at the beginning of growth process, and V{sup 4+} cations were partially oxidized to V{sup 5+} cations at the higher depositing temperature (250-450 deg. C). Various morphologies of VO{sub x} were attributed to the mixed microstructure of V{sub 2}O{sub 5} and VO{sub 2}. The difference between V{sup 4+}-O and V{sup 5+}-O bonds induced the distortion and various structures in VO{sub x}. When the depositing temperature was as high as 500 deg. C, most of the V{sup 4+} cations were oxidized to V{sup 5+} cations and V{sub 2}O{sub 5} rods were obtained.

  4. Suitable alkaline for graphene peeling grown on metallic catalysts using chemical vapor deposition

    International Nuclear Information System (INIS)

    Karamat, S.; Sonuşen, S.; Çelik, Ü.; Uysallı, Y.; Oral, A.

    2016-01-01

    Graphical abstract: - Highlights: • Graphene layers were grown on Pt and Cu foil via ambient pressure chemical vapor deposition method and for the delicate removal of graphene from metal catalysts, electrolysis method was used by using different alkaline (sodium hydroxide, potassium hydroxide, lithium hydroxide and barium hydroxide). • The delamination speed of PMMA/graphene stack was higher during the KOH and LiOH electrolysis as compare to NaOH and Ba(OH) 2 . Ba(OH) 2 is not advisable because of the residues left on the graphene surface which would further trapped in between graphene and SiO 2 /Si surface after transfer. The average peeling time in case of Pt electrode is ∼6 min for KOH and LiOH and ∼15 min for NaOH and Ba(OH) 2 . • Electrolysis method also works for the Cu catalyst. The peeling of graphene was faster in the case of Cu foil due to small size of bubbles which moves faster between the stack and the electrode surface. The average peeling time was ∼3–5 min. • XPS analysis clearly showed that the Pt substrates can be re-used again. Graphene layer was transferred to SiO 2 /Si substrates and to the flexible substrate by using the same peeling method. - Abstract: In chemical vapor deposition, the higher growth temperature roughens the surface of the metal catalyst and a delicate method is necessary for the transfer of graphene from metal catalyst to the desired substrates. In this work, we grow graphene on Pt and Cu foil via ambient pressure chemical vapor deposition (AP-CVD) method and further alkaline water electrolysis was used to peel off graphene from the metallic catalyst. We used different electrolytes i.e., sodium hydroxide (NaOH), potassium hydroxide (KOH), lithium hydroxide (LiOH) and barium hydroxide Ba(OH) 2 for electrolysis, hydrogen bubbles evolved at the Pt cathode (graphene/Pt/PMMA stack) and as a result graphene layer peeled off from the substrate without damage. The peeling time for KOH and LiOH was ∼6 min and for Na

  5. Comparative investigation of smooth polycrystalline diamond films on dental burs by chemical vapor deposition

    Science.gov (United States)

    Sein, Htet; Ahmed, Waqar; Rego, Christopher; Jackson, Mark; Polini, Riccardo

    2006-04-01

    Depositions of hot filament chemical vapor-deposited diamond on cobalt-cemented tungsten carbide (WC-Co) rotary cutting dental burs are presented. Conventional dental tools made of sintered polycrystalline diamond have a number of problems associated with the heterogeneity of the crystallite, decreased cutting efficiency, and short life. A preferential (111) faceted diamond was obtained after 15 h of deposition at a growth rate of 1.1 µm/h. Diamond-coated WC-Co dental burs and conventional sintered burs are mainly used in turning, milling, and drilling operations for machining metal ceramic hard alloys such as CoCr, composite teeth, and aluminum alloy in the dental laboratory. The influence of structure, the mechanical characteristics of both diamond grains and hard alloys on the wear behavior, as well as the regimen of grinding on diamond wear are considered. Erosion wear properties are also investigated under air-sand erosion testing. After machining with excessive cutting performance, calculations can be made on flank and crater wear areas. Diamond-coated WC-Co dental burs offered significantly better erosion and wear resistance compared with uncoated WC-Co tools and sintered burs.

  6. Electrical Characterization of Ti-Silicate Films Grown by Atomic Layer Chemical Vapor Deposition

    Science.gov (United States)

    Lee, Seungjae; Yong, Kijung

    2007-08-01

    Electrical characterization was performed for Ti-silicate films, which were deposited by atomic layer chemical vapor deposition (ALCVD). Before the deposition of Ti-silicate films, the silicon substrates were pretreated differently using hydrofluoric acid (HF)-etching, chemical oxidation, and thermal oxidation. Regardless of the pretreatment methods, the grown films showed a highly smooth surface with rms below 0.52 nm. The electrical properties of the grown Ti-silicate films showed a strong dependence on the substrate pretreatments. The 5-nm-thick Ti-silicate films grown on hydrogen-passivated Si and chemically oxidized Si showed rather high leakage currents, whereas the films grown on thermally oxidized Si showed low leakage currents below 1× 10-7 A/cm2 at a bias of -1 V. All of the films showed a positive shift in the flatband voltage (VFB) upon annealing. Also, each film showed low a hysteresis below 180 mV and the hysteresis decreased upon annealing.

  7. Surface modification of silicon-containing fluorocarbon films prepared by plasma-enhanced chemical vapor deposition

    Science.gov (United States)

    Jin, Yoonyoung; Desta, Yohannes; Goettert, Jost; Lee, G. S.; Ajmera, P. K.

    2005-07-01

    Surface modification of silicon-containing fluorocarbon (SiCF) films achieved by wet chemical treatments and through x-ray irradiation is examined. The SiCF films were prepared by plasma-enhanced chemical vapor deposition, using gas precursors of tetrafluoromethane and disilane. As-deposited SiCF film composition was analyzed by x-ray photoelectron spectroscopy. Surface modification of SiCF films utilizing n-lithiodiaminoethane wet chemical treatment is discussed. Sessile water-drop contact angle changed from 95°+/-2° before treatment to 32°+/-2° after treatment, indicating a change in the film surface characteristics from hydrophobic to hydrophilic. For x-ray irradiation on the SiCF film with a dose of 27.4 kJ/cm3, the contact angle of the sessile water drop changed from 95°+/-2° before radiation to 39°+/-3° after x-ray exposure. The effect of x-ray exposure on chemical bond structure of SiCF films is studied using Fourier transform infrared measurements. Electroless Cu deposition was performed to test the applicability of the surface modified films. The x-ray irradiation method offers a unique advantage in making possible surface modification in a localized area of high-aspect-ratio microstructures. Fabrication of a Ti-membrane x-ray mask is introduced here for selective surface modification using x-ray irradiation.

  8. Plasma and Ion Assistance in Physical Vapor Deposition: A Historical Perspective

    International Nuclear Information System (INIS)

    Anders, Andre

    2007-01-01

    Deposition of films using plasma or plasma-assist can be traced back surprisingly far, namely to the 18th century for arcs and to the 19th century for sputtering. However, only since the 1960s the coatings community considered other processes than evaporation for large scale commercial use. Ion Plating was perhaps the first important process, introducing vapor ionization and substrate bias to generate a beam of ions arriving on the surface of the growing film. Rather independently, cathodic arc deposition was established as an energetic condensation process, first in the former Soviet Union in the 1970s, and in the 1980s in the Western Hemisphere. About a dozen various ion-based coating technologies evolved in the last decades, all characterized by specific plasma or ion generation processes. Gridded and gridless ion sources were taken from space propulsion and applied to thin film deposition. Modeling and simulation have helped to make plasma and ions effects to be reasonably well understood. Yet--due to the complex, often non-linear and non-equilibrium nature of plasma and surface interactions--there is still a place for the experience plasma 'sourcerer'

  9. Crack-free yttria stabilized zirconia thin films by aerosol assisted chemical vapor deposition: Influence of water and carrier gas

    Energy Technology Data Exchange (ETDEWEB)

    Schlupp, M.V.F., E-mail: Meike.Schlupp@mat.ethz.ch [Nonmetallic Inorganic Materials, ETH Zuerich, Wolfgang-Pauli-Str. 10, 8093 Zuerich (Switzerland); Binder, S.; Martynczuk, J.; Prestat, M. [Nonmetallic Inorganic Materials, ETH Zuerich, Wolfgang-Pauli-Str. 10, 8093 Zuerich (Switzerland); Gauckler, L.J. [Nonmetallic Inorganic Materials, ETH Zuerich, Wolfgang-Pauli-Str. 10, 8093 Zuerich (Switzerland); International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395 (Japan)

    2012-11-01

    Yttria stabilized zirconia thin films are deposited on silicon single crystal substrates by aerosol assisted chemical vapor deposition from precursor solutions of zirconium and yttrium 2,4-pentanedionate in ethanol. Continuous films are obtained using pure oxygen, pure nitrogen, or mixtures of both as carrier gas. In the simultaneous presence of water and oxygen, crack formation is observed for films deposited at intermediate substrate temperatures (450 Degree-Sign C), while those deposited at low (300 Degree-Sign C) and high (600 Degree-Sign C) temperatures remain crack-free. Crack-free films can be deposited at 450 Degree-Sign C in a water-free setting, or in the presence of water using pure nitrogen as carrier gas. The addition of water to the precursor solutions also significantly reduces film growth rates. - Highlights: Black-Right-Pointing-Pointer Thin film deposition by aerosol assisted chemical vapor deposition (AA-CVD) Black-Right-Pointing-Pointer Yttria stabilized zirconia (YSZ) thin films deposited between 300 Degree-Sign C and 600 Degree-Sign C Black-Right-Pointing-Pointer Water decreases growth rates and leads to crack formation in AA-CVD of YSZ. Black-Right-Pointing-Pointer Crack-free YSZ thin films deposited using oxygen and/or nitrogen as carrier gas Black-Right-Pointing-Pointer YSZ thin films deposited by AA-CVD show low shrinkage on annealing at 1000 Degree-Sign C.

  10. Striped Phase of 3-Hexylthiophene Self-Assembled Monolayers on Au(1 11) Formed by Vapor Phase Deposition.

    Science.gov (United States)

    Kim, Youngwoo; Kang, Hungu; Tsunoi, Azuho; Hayashi, Tomohiro; Hara, Masahiko; Noh, Jaegeun

    2016-03-01

    The formation and surface structure of 3-hexylthiophene (HTP) self-assembled monolayers (SAMs) on Au(111) prepared by solution and ambient-pressure vapor deposition at room temperature (RT) for 24 h were examined by means of scanning tunneling microscopy (STM) and cyclic voltammetry (CV). STM imaging revealed that HTP SAMs formed by solution deposition have a disordered phase, whereas those formed by vapor deposition exhibit a striped phase with a unidirectional orientation. The distance between the rows in the striped phase was measured to be 1.3 ± 0.1 nm, and the hexyl molecular backbones of HTP in the SAMs on Au(111) are oriented parallel to the Au(111) surface with the head-to-head orientation. From this STM observation, we suggest that the formation of this striped phase in HTP SAMs prepared by vapor deposition were mainly driven by the optimization of van der Waals interactions between the hexyl chains on the surface. CV measurements also demonstrated that HTP SAMs show a high blocking efficiency for electron transfer reactions between electrolytes and the gold electrode, suggesting the formation of SAMs on Au(111) from the vapor phase. Our results obtained here will be very useful for understanding the formation and structure of HTP SAMs on Au(111) surfaces and how they are influenced by deposition method.

  11. Microstructural Effects and Properties of Non-line-of-Sight Coating Processing via Plasma Spray-Physical Vapor Deposition

    Science.gov (United States)

    Harder, Bryan J.; Zhu, Dongming; Schmitt, Michael P.; Wolfe, Douglas E.

    2017-08-01

    Plasma spray-physical vapor deposition (PS-PVD) is a unique processing method that bridges the gap between conventional thermal spray and vapor phase methods, and enables highly tailorable coatings composed of a variety of materials in thin, dense layers or columnar microstructures with modification of the processing conditions. The strengths of this processing technique are material and microstructural flexibility, deposition speed, and potential for non-line-of-sight (NLOS) capability by vaporization of the feedstock material. The NLOS capability of PS-PVD is investigated here using yttria-stabilized zirconia and gadolinium zirconate, which are materials of interest for turbine engine applications. PS-PVD coatings were applied to static cylindrical substrates approximately 6-19 mm in diameter to study the coating morphology as a function of angle. In addition, coatings were deposited on flat substrates under various impingement configurations. Impingement angle had significant effects on the deposition mode, and microscopy of coatings indicated that there was a shift in the deposition mode at approximately 90° from incidence on the cylindrical samples, which may indicate the onset of more turbulent flow and PVD-like growth. Coatings deposited at non-perpendicular angles exhibited a higher density and nearly a 2× improvement in erosion performance when compared to coatings deposited with the torch normal to the surface.

  12. Growth and luminescence of ternary semiconductor ZnCdSe nanowires by metalorganic chemical vapor deposition.

    Science.gov (United States)

    Zhang, X T; Liu, Z; Li, Quan; Hark, S K

    2005-09-29

    ZnCdSe alloy nanowires were successfully grown on the GaAs (100) substrate by metalorganic chemical vapor deposition using Au as a catalyst. The nanowires display two distinct types of morphology. The majority of them are straight, uniform in diameter, and have a smooth surface. However, a significant portion of them contain one or two constrictions along their length. The alloy is found to be rich in Zn; its composition, as determined from X-ray diffraction and energy-dispersive X-ray microanalysis, is close to Zn(0.9)Cd(0.1)Se. The peak energy of its room temperature near-band-edge photoluminescence is also consistent with this composition. X-ray diffraction pattern and transmission electron microscopy find both types of nanowires to be single crystalline, have the metastable wurtzite structure, and a growth direction along 100. The presence of an Au-Cd-Zn alloy particle at the tip of the nanowires supports vapor-liquid-solid as the growth mechanism. The appearance of constrictions in some of the nanowires is found to be linked to the existence of structural defects, possibly stacking faults, during growth.

  13. Impact of inactive dopants in chemical vapor deposition layers on photomodulated optical reflectance

    Energy Technology Data Exchange (ETDEWEB)

    Bogdanowicz, Janusz [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Electrical Engineering Department, INSYS, KU Leuven, Kasteelpark Arenberg 10, B-3001 Leuven (Belgium)], E-mail: Janusz.Bogdanowicz@imec.be; Dortu, Fabian [Multitel, rue Pierre et Marie Curie 2, 7000 Mons (Belgium); Clarysse, Trudo [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Vandervorst, Wilfried [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Instituut voor Kern- en Stralingsfysika, KU Leuven, B-3001 Leuven (Belgium); Shaughnessy, Derrick; Salnik, Alex; Nicolaides, Lena [KLA-Tencor Corp., 160 Rio Robles, San Jose, CA 95134 (United States)

    2008-12-05

    The ITRS roadmap stresses the electrical characterization of the active doping profiles for sub-32 nm structures as a key challenge for future CMOS technology. Earlier work has shown the promising capabilities of non-destructive photomodulated optical reflectance (PMOR) techniques, based on the localized detection of variations in the reflectivity of the sample, due to thermal and plasma (excess carrier) effects as can be generated by a modulated pump laser such as the Therma-Probe (TP) system. In this work, we study the impact of the inactive dopant atoms in chemical vapor deposition (CVD) layers both on PMOR and DC reflectance signals. In particular, with the help of numerical simulations, this work shows that, by taking into account the combined degradation of the thermal diffusivity and the recombination lifetime as well as the enhancement of the absorption coefficient, the theory may be rendered semi-quantitative.

  14. Modeling and designing a new gas injection diffusion system for metalorganic chemical vapor deposition

    Science.gov (United States)

    Liao, C. C.; Hsiau, S. S.; Chuang, T. C.

    2018-01-01

    Metalorganic chemical vapor deposition (MOCVD) is a critical process and is widely used for the epitaxial growth of light-emitting diode (LED) wafers. The key component, a gas injection system, delivers the gas into the reactor by using a nozzle or showerhead. In this paper, the numerical simulation method was applied to investigate the thermal fluid field and to design a new gas injection system for MOCVD. In this study, we developed a new gas injection system with inlet barriers. The inlet barriers can separate the various reactive gases, reduce the prereaction, and prevent adducted particles from forming and blocking the inlet gas system. The barrier geometry, including the barrier length, the barrier inclination angle, and the V/III precursor ratio was systematically studied to determine the optimal design conditions. Higher growth rate and improved uniformity were demonstrated using the new optimal gas inlet barrier design.

  15. Spin-Polarized Tunneling through Chemical Vapor Deposited Multilayer Molybdenum Disulfide.

    Science.gov (United States)

    Dankert, André; Pashaei, Parham; Kamalakar, M Venkata; Gaur, Anand P S; Sahoo, Satyaprakash; Rungger, Ivan; Narayan, Awadhesh; Dolui, Kapildeb; Hoque, Md Anamul; Patel, Ram Shanker; de Jong, Michel P; Katiyar, Ram S; Sanvito, Stefano; Dash, Saroj P

    2017-06-27

    The two-dimensional (2D) semiconductor molybdenum disulfide (MoS 2 ) has attracted widespread attention for its extraordinary electrical-, optical-, spin-, and valley-related properties. Here, we report on spin-polarized tunneling through chemical vapor deposited multilayer MoS 2 (∼7 nm) at room temperature in a vertically fabricated spin-valve device. A tunnel magnetoresistance (TMR) of 0.5-2% has been observed, corresponding to spin polarization of 5-10% in the measured temperature range of 300-75 K. First-principles calculations for ideal junctions result in a TMR up to 8% and a spin polarization of 26%. The detailed measurements at different temperature, bias voltages, and density functional theory calculations provide information about spin transport mechanisms in vertical multilayer MoS 2 spin-valve devices. These findings form a platform for exploring spin functionalities in 2D semiconductors and understanding the basic phenomena that control their performance.

  16. Spiral growth of few-layer MoS{sub 2} by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Dong, X.; Yan, C.; Tomer, D.; Li, L., E-mail: lianli@uwm.edu [Department of Physics, University of Wisconsin, Milwaukee, Wisconsin 53211 (United States); Li, C. H. [Naval Research Laboratory, Washington, DC 20375 (United States)

    2016-08-01

    Growth spirals exhibit appealing properties due to a preferred layer stacking and lack of inversion symmetry. Here, we report spiral growth of MoS{sub 2} during chemical vapor deposition on SiO{sub 2}/Si and epitaxial graphene/SiC substrates, and their physical and electronic properties. We determine the layer-dependence of the MoS{sub 2} bandgap, ranging from 2.4 eV for the monolayer to a constant of 1.3 eV beyond the fifth layer. We further observe that spirals predominantly initiate at the step edges of the SiC substrate, based on which we propose a growth mechanism driven by screw dislocation created by the coalescence of two growth fronts at steps.

  17. Investigation on the corrosion behavior of physical vapor deposition coated high speed steel

    Directory of Open Access Journals (Sweden)

    R Ravi Raja Malarvannan

    2015-08-01

    Full Text Available This work emphasizes on the influence of the TiN and AlCrN coatings fabricated on high speed steel form tool using physical vapor deposition technique. The surface microstructure of the coatings was studied using scanning electron microscope. Hardness and corrosion studies were also performed using Vickers hardness test and salt spray testing, respectively. The salt spray test results suggested that the bilayer coated (TiN- bottom layer and AlCrN- top layer substrate has undergone less amount of corrosion, and this is attributed to the dense microstructure. In addition to the above, the influence of the above coatings on the machining performance of the high speed steel was also evaluated and compared with that of the uncoated material and the results suggested that the bilayered coating has undergone very low weight loss when compared with that of the uncoated substrate depicting enhanced wear resistance.

  18. SiO2 coating of silver nanoparticles by photoinduced chemical vapor deposition.

    Science.gov (United States)

    Boies, Adam M; Roberts, Jeffrey T; Girshick, Steven L; Zhang, Bin; Nakamura, Toshitaka; Mochizuki, Amane

    2009-07-22

    Gas-phase silver nanoparticles were coated with silicon dioxide (SiO2) by photoinduced chemical vapor deposition (photo-CVD). Silver nanoparticles, produced by inert gas condensation, and a SiO2 precursor, tetraethylorthosilicate (TEOS), were exposed to vacuum ultraviolet (VUV) radiation at atmospheric pressure and varying temperatures. The VUV photons dissociate the TEOS precursor, initiating a chemical reaction that forms SiO2 coatings on the particle surfaces. Coating thicknesses were measured for a variety of operation parameters using tandem differential mobility analysis and transmission electron microscopy. The chemical composition of the particle coatings was analyzed using energy dispersive x-ray spectrometry and Fourier transform infrared spectroscopy. The highest purity films were produced at 300-400 degrees C with low flow rates of additional oxygen. The photo-CVD coating technique was shown to effectively coat nanoparticles and limit core particle agglomeration at concentrations up to 10(7) particles cm(-3).

  19. Carbon nanowalls grown by microwave plasma enhanced chemical vapor deposition during the carbonization of polyacrylonitrile fibers

    International Nuclear Information System (INIS)

    Li Jiangling; Su Shi; Kundrát, Vojtěch; Abbot, Andrew M.; Ye, Haitao; Zhou Lei; Mushtaq, Fajer; Ouyang Defang; James, David; Roberts, Darren

    2013-01-01

    We used microwave plasma enhanced chemical vapor deposition (MPECVD) to carbonize an electrospun polyacrylonitrile (PAN) precursor to form carbon fibers. Scanning electron microscopy, Raman spectroscopy, and Fourier transform infrared spectroscopy were used to characterize the fibers at different evolution stages. It was found that MPECVD-carbonized PAN fibers do not exhibit any significant change in the fiber diameter, whilst conventionally carbonized PAN fibers show a 33% reduction in the fiber diameter. An additional coating of carbon nanowalls (CNWs) was formed on the surface of the carbonized PAN fibers during the MPECVD process without the assistance of any metallic catalysts. The result presented here may have a potential to develop a novel, economical, and straightforward approach towards the mass production of carbon fibrous materials containing CNWs.

  20. Anisotropic growth mechanism of tungsten diselenide domains using chemical vapor deposition method

    Science.gov (United States)

    Lee, Yoobeen; Jeong, Heekyung; Park, Yi-Seul; Han, Seulki; Noh, Jaegeun; Lee, Jin Seok

    2018-02-01

    Anisotropic transition metal dichalcogenide (TMDC) domains have stimulated a growing interest mainly due to their electronic properties that depend on the size, shape, and edge structures of the domains. In this work, we investigated the anisotropic morphogenesis and edge terminations of tungsten diselenide (WSe2) domains grown on sapphire substrates by chemical vapor deposition (CVD) using tungsten oxide (WO3) and selenium (Se) powders as precursors. We varied the amount of Se powder and growth temperature during the CVD process, which in turn caused variations in the growth mechanism and kinetic energies of precursors. We succeeded in synthesizing hexagonal, square, circular, and triangular anisotropic WSe2 domains. They were characterized using scanning electron microscopy (SEM), Raman spectroscopy, photoluminescence (PL) analyses, and atomic force microscopy (AFM). Furthermore, we proposed the growth mechanism of anisotropic WSe2 domains with different edge terminations based on experimental observations through scanning tunneling microscope (STM).

  1. Environmental effects on the tensile strength of chemically vapor deposited silicon carbide fibers

    Science.gov (United States)

    Bhatt, R. T.; Kraitchman, M. D.

    1985-01-01

    The room temperature and elevated temperature tensile strengths of commercially available chemically vapor-deposited (CVD) silicon carbide fibers were measured after 15 min heat treatment to 1600 C in various environments. These environments included oxygen, air, argon and nitrogen at one atmosphere and vacuum at 10/9 atmosphere. Two types of fibers were examined which differed in the SiC content of their carbon-rich coatings. Threshold temperature for fiber strength degradation was observed to be dependent on the as-received fiber-flaw structure, on the environment and on the coating. Fractographic analyses and flexural strength measurements indicate that tensile strength losses were caused by surface degradation. Oxidation of the surface coating is suggested as one possible degradation mechanism. The SiC fibers containing the higher percentage of SiC near the surface of the carbon-rich coating show better strength retention and higher elevated temperature strength.

  2. Monatomic chemical-vapor-deposited graphene membranes bridge a half-millimeter-scale gap.

    Science.gov (United States)

    Lee, Choong-Kwang; Hwangbo, Yun; Kim, Sang-Min; Lee, Seoung-Ki; Lee, Seung-Mo; Kim, Seong-Su; Kim, Kwang-Seop; Lee, Hak-Joo; Choi, Byung-Ik; Song, Chang-Kyu; Ahn, Jong-Hyun; Kim, Jae-Hyun

    2014-03-25

    One of the main concerns in nanotechnology is the utilization of nanomaterials in macroscopic applications without losing their extreme properties. In an effort to bridge the gap between the nano- and macroscales, we propose a clever fabrication method, the inverted floating method (IFM), for preparing freestanding chemical-vapor-deposited (CVD) graphene membranes. These freestanding membranes were then successfully suspended over a gap a half-millimeter in diameter. To understand the working principle of IFM, high-speed photography and white light interferometry were used to characterize and analyze the deformation behaviors of the freestanding graphene membranes in contact with a liquid during fabrication. Some nanoscale configurations in the macroscopic graphene membranes were able to be characterized by simple optical microscopy. The proposed IFM is a powerful approach to investigating the macroscopic structures of CVD graphene and enables the exploitation of freestanding CVD graphene for device applications.

  3. Study of surface morphology and alignment of MWCNTs grown by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Shukrullah, S., E-mail: zshukrullah@gmail.com, E-mail: noranimuti-mohamed@petronas.com.my, E-mail: maizats@petronas.com.my; Mohamed, N. M., E-mail: zshukrullah@gmail.com, E-mail: noranimuti-mohamed@petronas.com.my, E-mail: maizats@petronas.com.my; Shaharun, M. S., E-mail: zshukrullah@gmail.com, E-mail: noranimuti-mohamed@petronas.com.my, E-mail: maizats@petronas.com.my [Department of Fundamental and Applied Sciences, Universiti Teknologi PETRONAS, 31750 Tronoh, Perak (Malaysia); Yasar, M., E-mail: Muhammad.yasar@ieee.org [Department of Electrical and Electronic Engineering, Universiti Teknologi PETRONAS, 31750 Tronoh, Perak (Malaysia)

    2014-10-24

    In this research work, Multiwalled Carbon Nanotubes (MWCNTs) have been synthesized successfully by using floating catalytic chemical vapor deposition (FCCVD) method. Different ferrocene amounts (0.1, 0.125 and 0.15 g) were used as catalyst and ethylene was used as a carbon precursor at reaction temperature of 800°C. Characterization of the grown MWCNTs was carried out by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The obtained data showed that the catalyst weight affects the nanotubes diameter, alignment, crystallinity and growth significantly, whereas negligible influence was noticed on CNTs forest length. The dense, uniform and meadow like patterns of grown CNTs were observed for 0.15 g ferrocene. The average diameter of the grown CNTs was found in the range of 32 to 75 nm. Close inspection of the TEM images also confirmed the defects in some of the grown CNTs, where few black spots were evident in CNTs structure.

  4. Structured nanocarbon on various metal foils by microwave plasma enhanced chemical vapor deposition

    International Nuclear Information System (INIS)

    Rius, G; Yoshimura, M

    2013-01-01

    We present a versatile process for the engineering of nanostructures made of crystalline carbon on metal foils. The single step process by microwave plasma-enhance chemical vapor deposition is demonstrated for various substrate materials, such as Ni or Cu. Either carbon nanotubes (CNT) or carbon nanowalls (CNW) are obtained under same growth conditions and without the need of additional catalyst. The use of spacer and insulator implies a certain control over the kind of allotropes that are obtained. High density and large surface area are morphological characteristics of the thus obtained C products. The possibility of application on many metals, and in the alloy composition, on as-delivered commercially available foils indicates that this strategy can be adapted to a bunch of specific applications, while the production of C nanostructures is of remarkable simplicity.

  5. Laterally Stitched Heterostructures of Transition Metal Dichalcogenide: Chemical Vapor Deposition Growth on Lithographically Patterned Area

    KAUST Repository

    Li, Henan

    2016-10-31

    Two-dimensional transition metal dichalcogenides (TMDCs) have shown great promise in electronics and optoelectronics due to their unique electrical and optical properties. Heterostructured TMDC layers such as the laterally stitched TMDCs offer the advantages of better electronic contact and easier band offset tuning. Here, we demonstrate a photoresist-free focused ion beam (FIB) method to pattern as-grown TMDC monolayers by chemical vapor deposition, where the exposed edges from FIB etching serve as the seeds for growing a second TMDC material to form desired lateral heterostructures with arbitrary layouts. The proposed lithographic and growth processes offer better controllability for fabrication of the TMDC heterostrucuture, which enables the construction of devices based on heterostructural monolayers. © 2016 American Chemical Society.

  6. Complete long-term corrosion protection with chemical vapor deposited graphene

    DEFF Research Database (Denmark)

    Yu, Feng; Camilli, Luca; Wang, Ting

    2018-01-01

    -graphene hybrid coating, comprising two single layers of CVD graphene sandwiched by three layers of polyvinyl butyral, which provides complete corrosion protection of commercial aluminum alloys even after 120 days of exposure to simulated seawater. The essential role played by graphene in the hybrid coating......Despite numerous reports regarding the potential of graphene for corrosion protection, examples of chemical vapor deposited (CVD) graphene-based anticorrosive coatings able to provide long-term protection (i.e. several months) of metals have so far been absent. Here, we present a polymer...... coatings, which can be extended to other two-dimensional materials and polymers, for long-term protection of various relevant metals and alloys....

  7. Large single crystals of graphene on melted copper using chemical vapor deposition.

    Science.gov (United States)

    Wu, Yimin A; Fan, Ye; Speller, Susannah; Creeth, Graham L; Sadowski, Jerzy T; He, Kuang; Robertson, Alex W; Allen, Christopher S; Warner, Jamie H

    2012-06-26

    A simple method is presented for synthesizing large single crystal graphene domains on melted copper using atmospheric pressure chemical vapor deposition (CVD). This is achieved by performing the reaction above the melting point of copper (1090 °C) and using a molybdenum or tungsten support to prevent balling of the copper from dewetting. By controlling the amount of hydrogen during growth, individual single crystal domains of monolayer graphene greater than 200 μm are produced within a continuous film. Stopping growth before a complete film is formed reveals individual hexagonal domains of graphene that are epitaxially aligned in their orientation. Angular resolved photoemission spectroscopy is used to show that the graphene grown on copper exhibits a linear dispersion relationship and no sign of doping. HRTEM and electron diffraction reveal a uniform high quality crystalline atomic structure of monolayer graphene.

  8. Few-atomic-layered boron carbonitride nanosheets prepared by chemical vapor deposition.

    Science.gov (United States)

    Qin, Li; Yu, Jie; Kuang, Shengyong; Xiao, Chang; Bai, Xuedong

    2012-01-07

    Few-atomic-layered boron carbonitride (BCN) nanosheets have been grown on Si substrate by microwave plasma chemical vapor deposition from a gas mixture of CH(4)-N(2)-H(2)-BF(3). The grown BCN nanosheets are oriented with their base planes perpendicular to the substrate surface. Ultrathin BCN nanosheets with thickness from 2 to a few atomic layers account for a considerable portion of the products, although many of them have more than 10 layers. Photoluminescence is measured for the BCN nanosheets and intense emission at 3.27 eV with very weak defect-related emission is observed for the nanosheets with the composition of B(0.38)C(0.27)N(0.35). The present BCN nanosheets are promising for applications in nanoelectronics, catalyst supports, gas adsorption, etc.

  9. Layer-dependent supercapacitance of graphene films grown by chemical vapor deposition on nickel foam

    KAUST Repository

    Chen, Wei

    2013-03-01

    High-quality, large-area graphene films with few layers are synthesized on commercial nickel foams under optimal chemical vapor deposition conditions. The number of graphene layers is adjusted by varying the rate of the cooling process. It is found that the capacitive properties of graphene films are related to the number of graphene layers. Owing to the close attachment of graphene films on the nickel substrate and the low charge-transfer resistance, the specific capacitance of thinner graphene films is almost twice that of the thicker ones and remains stable up to 1000 cycles. These results illustrate the potential for developing high-performance graphene-based electrical energy storage devices. © 2012 Elsevier B.V. All rights reserved.

  10. Catalytic Chemical Vapor Deposition Synthesis of Carbon Aerogels of High-Surface Area and Porosity

    Directory of Open Access Journals (Sweden)

    Armando Peña

    2012-01-01

    Full Text Available In this work carbon aerogels were synthesized by catalytic chemical vapor deposition method (CCVD. Ferrocene were employed as a source both of catalytic material (Fe and of carbon. Gaseous hydrogen and argon were used as reductant and carrier gas, respectively. The products of reaction were collected over alumina. The morphology and textural properties of the soot produced in the reaction chamber were investigated using Scanning Electron Microscopy, High-Resolution Transmission Electron Microscopy, X-ray photoelectron spectroscopy, and N2 physisorption (BET and BHJ methods. After the evaluation of the porous structure of the synthesized products, 780 ± 20 m2/g of SBET and 0.55 ± 0.02 cm3/g of VBJH were found. The presence of iron carbide and the partial oxidation of carbon nanostructures were revealed by XPS.

  11. Diameter control and emission properties of carbon nanotubes grown using chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kaatz, F.H.; Siegal, M.P.; Overmyer, D.L.; Provencio, P.P.; Jackson, J.L

    2003-01-15

    We grow multiwalled carbon nanotubes (CNTs) via thermal chemical vapor deposition from a sputtered 4-nm-thick nickel catalyst film on a tungsten-coated silicon substrate. CNTs grow from a mixture of nitrogen and acetylene gases at temperatures ranging from 630 to 790 deg. C, resulting in CNT outer diameters of 5-350 nm. CNT diameters increase exponentially with temperature. These results define regimes for template growth fabricated in catalytically active anodized aluminum oxide (AAO) with controlled pinhole sizes ranging from 10 to 50 nm. We measure a threshold electron emission field of 3 V/{mu}m and a field enhancement factor {beta}=5230 on randomly oriented 10-nm diameter CNTs.

  12. Diameter control and emission properties of carbon nanotubes grown using chemical vapor deposition

    International Nuclear Information System (INIS)

    Kaatz, F.H.; Siegal, M.P.; Overmyer, D.L.; Provencio, P.P.; Jackson, J.L.

    2003-01-01

    We grow multiwalled carbon nanotubes (CNTs) via thermal chemical vapor deposition from a sputtered 4-nm-thick nickel catalyst film on a tungsten-coated silicon substrate. CNTs grow from a mixture of nitrogen and acetylene gases at temperatures ranging from 630 to 790 deg. C, resulting in CNT outer diameters of 5-350 nm. CNT diameters increase exponentially with temperature. These results define regimes for template growth fabricated in catalytically active anodized aluminum oxide (AAO) with controlled pinhole sizes ranging from 10 to 50 nm. We measure a threshold electron emission field of 3 V/μm and a field enhancement factor β=5230 on randomly oriented 10-nm diameter CNTs

  13. Catalytic chemical vapor deposition and structural analysis of MoS2 nanotubes

    Science.gov (United States)

    Weng, Mengting; Zhang, Meiqi; Yanase, Takashi; Uehara, Fumiya; Nagahama, Taro; Shimada, Toshihiro

    2018-03-01

    MoS2 nanotubes were synthesized by chemical vapor deposition (CVD) using six-horned octahedral FeO nanoparticles and gasified MoO3 and sulfur. The morphology and structure of the nanotubes were characterized by scanning electron microscopy (SEM), Raman spectroscopy, and transmission electron microscopy (TEM), showing that the nanotubes had a hollow structure. The hexagonal lattice of MoS2 was aligned parallel to the direction of the nanotubes. The catalytic activities of the Fe films and nanoparticles of Fe2O3, NiO, and Cu2O for the growth of MoS2 nanotubes were investigated. FeO was found to be the most effective catalyst tested.

  14. Chemical-Vapor-Deposited Graphene as Charge Storage Layer in Flash Memory Device

    Directory of Open Access Journals (Sweden)

    W. J. Liu

    2016-01-01

    Full Text Available We demonstrated a flash memory device with chemical-vapor-deposited graphene as a charge trapping layer. It was found that the average RMS roughness of block oxide on graphene storage layer can be significantly reduced from 5.9 nm to 0.5 nm by inserting a seed metal layer, which was verified by AFM measurements. The memory window is 5.6 V for a dual sweep of ±12 V at room temperature. Moreover, a reduced hysteresis at the low temperature was observed, indicative of water molecules or −OH groups between graphene and dielectric playing an important role in memory windows.

  15. SiO2 coating of silver nanoparticles by photoinduced chemical vapor deposition

    International Nuclear Information System (INIS)

    Boies, Adam M; Girshick, Steven L; Roberts, Jeffrey T; Zhang Bin; Nakamura, Toshitaka; Mochizuki, Amane

    2009-01-01

    Gas-phase silver nanoparticles were coated with silicon dioxide (SiO 2 ) by photoinduced chemical vapor deposition (photo-CVD). Silver nanoparticles, produced by inert gas condensation, and a SiO 2 precursor, tetraethylorthosilicate (TEOS), were exposed to vacuum ultraviolet (VUV) radiation at atmospheric pressure and varying temperatures. The VUV photons dissociate the TEOS precursor, initiating a chemical reaction that forms SiO 2 coatings on the particle surfaces. Coating thicknesses were measured for a variety of operation parameters using tandem differential mobility analysis and transmission electron microscopy. The chemical composition of the particle coatings was analyzed using energy dispersive x-ray spectrometry and Fourier transform infrared spectroscopy. The highest purity films were produced at 300-400 0 C with low flow rates of additional oxygen. The photo-CVD coating technique was shown to effectively coat nanoparticles and limit core particle agglomeration at concentrations up to 10 7 particles cm -3 .

  16. Uniformity of quantum well heterostructure GaAlAs lasers grown by metalorganic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Scifres, D.R.; Burnham, R.D.; Bernstein, M.; Chung, H.; Endicott, F.; Mosby, W.; Tramontana, J.; Walker, J.; Yingling, R.D. Jr.

    1982-09-15

    The threshold current density, laser wavelength, grown layer thickness, reverse breakdown voltage, and far-field radiation pattern as a function of position on the grown wafer are reported for broad area multiple quantum well GaAlAs heterostructure lasers grown by metalorganic chemical vapor deposition. It is found that the layer thickness varies across a 1.5-in. sample by as much as 20% at the outer edges of the water, leading to a lasing wavelength shift of as much as 150 A owing to the quantum size effect. It is shown that this thickness variation has only a small effect on the threshold current density across the water such that the uniformity of threshold current density is comparable to that reported previously for molecular beam epitaxy-grown conventional double heterostructure lasers.

  17. Formation of SiC thin films by chemical vapor deposition with vinylsilane precursor

    Science.gov (United States)

    Doi, Takuma; Takeuchi, Wakana; Jin, Yong; Kokubun, Hiroshi; Yasuhara, Shigeo; Nakatsuka, Osamu; Zaima, Shigeaki

    2018-01-01

    We have examined the formation of SiC thin films by chemical vapor deposition (CVD) using vinylsilane and investigated the chemical bonding state and crystallinity of the prepared SiC thin films. We achieved the formation of a Si–H–less SiC film at growth temperatures as low as 600 °C. Also, we investigated the in situ doping effect of N by the incorporation of NH3 gas in the SiC growth and demonstrated that the chemical composition of N in SiC thin films was controlled by adjusting the NH3 flow rate. In addition, we examined the growth of SiC thin films on a Cu substrate and achieved the formation of a SiC thin film while avoiding any significant reaction between SiC and Cu at a growth temperature of 700 °C.

  18. Synthesis of carbon nanowall by plasma-enhanced chemical vapor deposition method.

    Science.gov (United States)

    Liu, Rulin; Chi, Yaqing; Fang, Liang; Tang, Zhensen; Yi, Xun

    2014-02-01

    Plasma-enhanced chemical vapor deposition (PECVD) is widely used for the synthesis of carbon materials, such as diamond-like carbons (DLCs), carbon nanotubes (CNTs) and carbon nanowalls (CNWs). Advantages of PECVD are low synthesis temperature compared with thermal CVD and the ability to grow vertically, free-standing structures. Due to its self-supported property and high specific surface area, CNWs are a promising material for field emission devices and other chemical applications. This article reviews the recent process on the synthesis of CNW by the PECVD method. We briefly introduce the structure and properties of CNW with characterization techniques. Growth mechanism is also discussed to analyze the influence of plasma conditions, substrates, temperature, and other parameters to the final film, which will give a suggestion on parameter modulation for desired film.

  19. Study of surface morphology and alignment of MWCNTs grown by chemical vapor deposition

    International Nuclear Information System (INIS)

    Shukrullah, S.; Mohamed, N. M.; Shaharun, M. S.; Yasar, M.

    2014-01-01

    In this research work, Multiwalled Carbon Nanotubes (MWCNTs) have been synthesized successfully by using floating catalytic chemical vapor deposition (FCCVD) method. Different ferrocene amounts (0.1, 0.125 and 0.15 g) were used as catalyst and ethylene was used as a carbon precursor at reaction temperature of 800°C. Characterization of the grown MWCNTs was carried out by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The obtained data showed that the catalyst weight affects the nanotubes diameter, alignment, crystallinity and growth significantly, whereas negligible influence was noticed on CNTs forest length. The dense, uniform and meadow like patterns of grown CNTs were observed for 0.15 g ferrocene. The average diameter of the grown CNTs was found in the range of 32 to 75 nm. Close inspection of the TEM images also confirmed the defects in some of the grown CNTs, where few black spots were evident in CNTs structure

  20. Nonstoichiometric composition shift in physical vapor deposition of CdTe thin films

    Science.gov (United States)

    Chin, Ken K.; Cheng, Zimeng; Delahoy, Alan E.

    2015-05-01

    While it is being debated whether Cd vacancy is an effective p-dopant in CdTe, and whether CdTe thin film in solar energy application should be Cd-deficient or Cd-rich, in the theory of CdTe physical vapor deposition (PVD) it has been assumed that both the source material and the thin film product is stoichiometric. To remediate the lack of effective theory, a new PVD model for CdTe photovoltaic (PV) modules is presented in this work, in which the composition of the CdTe thin film under growth is a parameter determined by the source CdTe composition as well as the growth condition. The solid phase Cd1-δTe1+δ compound under deposition temperature is treated as a solid solution with a mole of excess pure Te or Cd as solute and one mole of congruently grown CdTe as solvent. Assuming that the vapor pressure of Te2 can be calculated by using the law of solid solution PTe=H0+aH1+a2H2 round the congruent composition, where the molar number a and the constants H0, H1 and H2 as functions of temperature T are extracted from the experimental data. Thus, the mole fraction of solute in the grown CdTe thin film as well as the growth rate, as a function of the solute mole fraction in the source CdTe can be determined.

  1. Integrating atomic layer deposition and ultra-high vacuum physical vapor deposition for in situ fabrication of tunnel junctions.

    Science.gov (United States)

    Elliot, Alan J; Malek, Gary A; Lu, Rongtao; Han, Siyuan; Yu, Haifeng; Zhao, Shiping; Wu, Judy Z

    2014-07-01

    Atomic Layer Deposition (ALD) is a promising technique for growing ultrathin, pristine dielectrics on metal substrates, which is essential to many electronic devices. Tunnel junctions are an excellent example which require a leak-free, ultrathin dielectric tunnel barrier of typical thickness around 1 nm between two metal electrodes. A challenge in the development of ultrathin dielectric tunnel barriers using ALD is controlling the nucleation of dielectrics on metals with minimal formation of native oxides at the metal surface for high-quality interfaces between the tunnel barrier and metal electrodes. This poses a critical need for integrating ALD with ultra-high vacuum (UHV) physical vapor deposition. In order to address these challenges, a viscous-flow ALD chamber was designed and interfaced to an UHV magnetron sputtering chamber via a load lock. A sample transportation system was implemented for in situ sample transfer between the ALD, load lock, and sputtering chambers. Using this integrated ALD-UHV sputtering system, superconductor-insulator-superconductor (SIS) Nb-Al/Al2O2/Nb Josephson tunnel junctions were fabricated with tunnel barriers of thickness varied from sub-nm to ~1 nm. The suitability of using an Al wetting layer for initiation of the ALD Al2O3 tunnel barrier was investigated with ellipsometry, atomic force microscopy, and electrical transport measurements. With optimized processing conditions, leak-free SIS tunnel junctions were obtained, demonstrating the viability of this integrated ALD-UHV sputtering system for the fabrication of tunnel junctions and devices comprised of metal-dielectric-metal multilayers.

  2. Integrating atomic layer deposition and ultra-high vacuum physical vapor deposition for in situ fabrication of tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Elliot, Alan J., E-mail: alane@ku.edu, E-mail: jwu@ku.edu; Malek, Gary A.; Lu, Rongtao; Han, Siyuan; Wu, Judy Z., E-mail: alane@ku.edu, E-mail: jwu@ku.edu [Department of Physics and Astronomy, The University of Kansas, Lawrence, Kansas 66045 (United States); Yu, Haifeng; Zhao, Shiping [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-07-15

    Atomic Layer Deposition (ALD) is a promising technique for growing ultrathin, pristine dielectrics on metal substrates, which is essential to many electronic devices. Tunnel junctions are an excellent example which require a leak-free, ultrathin dielectric tunnel barrier of typical thickness around 1 nm between two metal electrodes. A challenge in the development of ultrathin dielectric tunnel barriers using ALD is controlling the nucleation of dielectrics on metals with minimal formation of native oxides at the metal surface for high-quality interfaces between the tunnel barrier and metal electrodes. This poses a critical need for integrating ALD with ultra-high vacuum (UHV) physical vapor deposition. In order to address these challenges, a viscous-flow ALD chamber was designed and interfaced to an UHV magnetron sputtering chamber via a load lock. A sample transportation system was implemented for in situ sample transfer between the ALD, load lock, and sputtering chambers. Using this integrated ALD-UHV sputtering system, superconductor-insulator-superconductor (SIS) Nb-Al/Al{sub 2}O{sub 2}/Nb Josephson tunnel junctions were fabricated with tunnel barriers of thickness varied from sub-nm to ∼1 nm. The suitability of using an Al wetting layer for initiation of the ALD Al{sub 2}O{sub 3} tunnel barrier was investigated with ellipsometry, atomic force microscopy, and electrical transport measurements. With optimized processing conditions, leak-free SIS tunnel junctions were obtained, demonstrating the viability of this integrated ALD-UHV sputtering system for the fabrication of tunnel junctions and devices comprised of metal-dielectric-metal multilayers.

  3. Properties of a-C:H:O plasma polymer films deposited from acetone vapors

    Energy Technology Data Exchange (ETDEWEB)

    Drabik, M., E-mail: martin.drabik@gmail.com [Empa, Swiss Federal Laboratories for Materials Science and Technology, Lerchenfeldstrasse 5, 9014 St. Gallen (Switzerland); Celma, C. [Empa, Swiss Federal Laboratories for Materials Science and Technology, Lerchenfeldstrasse 5, 9014 St. Gallen (Switzerland); Kousal, J.; Biederman, H. [Charles University in Prague, Faculty of Mathematics and Physics, Department of Macromolecular Physics, V Holešovičkách 2, 180 00 Prague 8 (Czech Republic); Hegemann, D. [Empa, Swiss Federal Laboratories for Materials Science and Technology, Lerchenfeldstrasse 5, 9014 St. Gallen (Switzerland)

    2014-12-31

    To gain insight into the deposition and stability of oxygen-containing plasma polymer films, the properties of amorphous oxygenated hydrocarbon (a-C:H:O) plasma polymer coatings deposited from acetone vapors under various experimental conditions are investigated. Apart from the discharge power, the influence of the reactive carbon dioxide (CO{sub 2}) gas on the structure of the resulting films is studied. It is found by characterization using X-ray Photoelectron Spectroscopy and Fourier-Transform Infrared Spectroscopy that the experimental conditions particularly influence the amount of oxygen in the deposited a-C:H:O plasma polymer films. The O/C elemental ratio increases with increasing amount of CO{sub 2} in the working gas mixture (up to 0.2 for 24 sccm of CO{sub 2} at 30 W) and decreases with increasing RF discharge power (down to 0.17 for 50 W). Furthermore, the nature of bonds between the oxygen and carbon atoms has been examined. Only low amounts of double and triple bonded carbon are observed. This has a particular influence on the aging of the plasma polymer films which is studied both in ambient air and in distilled water for up to 4 months. Overall, stable a-C:H:O plasma polymer films are deposited comprising low amounts (up to about 5%) of ester/carboxyl groups. - Highlights: • Hydrocarbon plasma polymer films with variable oxygen content can be prepared. • Stable oxygenated hydrocarbon plasma polymers contain max 5% of ester/carboxyl groups. • Acetone-derived plasma polymer films can be used as permanent hydrophilic surfaces.

  4. Ion-assisted doping of 2-6 compounds during physical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Bube, R H [Stanford Univ., CA (USA). Dept. of Materials Science and Engineering

    1990-07-01

    This report describes a research program to (1) investigate ion-assisted doping during chemical vapor deposition of CdTe and (2) determine the influence of co-depositing ionized dopant atoms in the growth and structural and photoelectronic properties of the deposited films. In p-CdTe homo-epitaxial films, we controlled doping up to about 6 {times} 10{sup 16} cm{sup {minus}3} and 2 {times} 10{sup 17} cm{sub {minus}3} or ion-assisted depositions with As and P ions, respectively. At a growth rate of approximately 0.1 {mu}m/min, a substrate temperature of 400{degree}C, and ion energy of 60 eV, a maximum doping density was found near an ion current of 0.6{mu}A/cm{sup 2}. Related studies included elucidating the role of low-energy ion damage in the ion-assisted doping process, and investigating the decrease in carrier density near the surface of p-CdTe upon heating in vacuum, H{sub 2}, or Ar. We demonstrate the ability to make carrier density profiles and to grade junctions, and we present preliminary results from polycrystalline p-CdTe films grown on graphite and alumina substrates. We also present solar cells prepared using the p-CdTe as the collector area and n-CdS as the window layer, and we examine their photovoltaic parameters for different carrier densities and configurations in p-CdTe. 91 refs., 44 figs., 5 tabs.

  5. Nanocrystalline diamond films deposited by the hot cathode direct current plasma chemical vapor deposition method with different compositions of CH4/Ar/H2 gas mixture

    NARCIS (Netherlands)

    Zeng, L.; Peng, H.; Wang, W.; Chen, Y.; Lei, D.; Qi, W.; Liang, J.; Zhao, J.; Kong, X.; Zhang, H.

    2008-01-01

    Nanocrystalline diamond films with different grain sizes were synthesized on Si substrate by the hot cathode direct current plasma chemical vapor deposition method with different compositions of CH4/Ar/H2 gas mixture. The morphology and microstructure of the obtained products were characterized by

  6. Final Report: Vapor Transport Deposition for Thin Film III-V Photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Boettcher, Shannon [Univ. of Oregon, Eugene, OR (United States); Greenaway, Ann [Univ. of Oregon, Eugene, OR (United States); Boucher, Jason [Univ. of Oregon, Eugene, OR (United States); Aloni, Shaul [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2016-02-10

    Silicon, the dominant photovoltaic (PV) technology, is reaching its fundamental performance limits as a single absorber/junction technology. Higher efficiency devices are needed to reduce cost further because the balance of systems account for about two-thirds of the overall cost of the solar electricity. III-V semiconductors such as GaAs are used to make the highest-efficiency photovoltaic devices, but the costs of manufacture are much too high for non-concentrated terrestrial applications. The cost of III-V’s is driven by two factors: (1) metal-organic chemical vapor deposition (MOCVD), the dominant growth technology, employs expensive, toxic and pyrophoric gas-phase precursors, and (2) the growth substrates conventionally required for high-performance devices are monocrystalline III-V wafers. The primary goal of this project was to show that close-spaced vapor transport (CSVT), using water vapor as a transport agent, is a scalable deposition technology for growing low-cost epitaxial III-V photovoltaic devices. The secondary goal was to integrate those devices on Si substrates for high-efficiency tandem applications using interface nanopatterning to address the lattice mismatch. In the first task, we developed a CSVT process that used only safe solid-source powder precursors to grow epitaxial GaAs with controlled n and p doping and mobilities/lifetimes similar to that obtainable via MOCVD. Using photoelectrochemical characterization, we showed that the best material had near unity internal quantum efficiency for carrier collection and minority carrier diffusions lengths in of ~ 8 μm, suitable for PV devices with >25% efficiency. In the second task we developed the first pn junction photovoltaics using CSVT and showed unpassivated structures with open circuit photovoltages > 915 mV and internal quantum efficiencies >0.9. We also characterized morphological and electrical defects and identified routes to reduce those defects. In task three we grew epitaxial

  7. Spectroscopic properties of nitrogen doped hydrogenated amorphous carbon films grown by radio frequency plasma-enhanced chemical vapor deposition

    OpenAIRE

    Y., Hayashi; G., Yu; M. M., Rahman; K. M., Krishna; Tetsuo, Soga; Takashi, Jimbo; Masayoshi, Umeno

    2001-01-01

    Nitrogen doped hydrogenated amorphous carbon thin films have been deposited by rf plasma-enhanced chemical vapor deposition using CH4 as the source of carbon and with different nitrogen flow rates (N2/CH4 gas ratios between 0 and 3), at 300 K. The dependence modifications of the optical and the structural properties on nitrogen incorporation were investigated using different spectroscopic techniques, such as, Raman spectroscopy, Fourier transform infrared spectroscopy, x-ray photoelectron spe...

  8. Structure and Growth of Vapor-Deposited n-Dotriacontane Films Studied by X-ray Reflectivity

    DEFF Research Database (Denmark)

    del Campo, V.; Cisternas, E.; Taub, H.

    2009-01-01

    We have used synchrotron X-ray reflectivity measurements to investigate the structure of n-dotriacontane (n-C32H66 or C32) films deposited from the vapor phase onto a SiO2-coated Si(100) surface. Our primary motivation was to determine whether the structure and growth mode of these films differ...... from those deposited from solution on the same substrate. The vapor-deposited films had a thickness of 50 Å thick as monitored in situ by high-resolution ellipsometry and were stable in air. Similar to the case of solution-deposited C32 films, we find that film growth in vacuum begins with a nearly...... vapor-deposited samples at atmospheric pressure above the bulk C32 melting point, we find the structure of our films as a function of temperature to be consistent with a phase diagram inferred previously for similarly treated solution-deposited films. Our results resolve some of the discrepancies...

  9. Luminescence and Structure of ZnO Grown by Physical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    R. García-Gutiérrez

    2012-01-01

    Full Text Available Nanostructured ZnO was deposited on different substrates (Si, SiO2, and Au/SiO2 by an enhanced physical vapor deposition technique that presents excellent luminescent properties. This technique consists in a horizontal quartz tube reactor that uses ultra-high purity Zn and UHP oxygen as precursors. The morphology and structure of ZnO grown in this work were studied by electron microscopy and X-ray diffraction. The XRD patterns revealed the highly crystalline phase of wurtzite polycrystalline structure, with a preferred (1011 growth direction. Room temperature cathodoluminescence studies revealed two features in the luminescence properties of the ZnO obtained by this technique, first a high-intensity narrow peak centered at 390 nm (~3.2 eV corresponding to a near band-to-band emission, and secondly, a broad peak centered around 517 nm (2.4 eV, the typical green-yellow luminescence, related to an unintentionally doped ZnO.

  10. Preparation of Al O N Films by Electron Cyclotron Resonance Plasma-Assisted Chemical Vapor Deposition

    Science.gov (United States)

    Goto, Takashi; Zhang, Wei; Hirai, Toshio

    1999-06-01

    Al O N films were prepared by electron cyclotron resonance plasma-assisted chemical vapor deposition (ECR PACVD) using an AlBr3 N2O N2 Ar H2 gas system. The structure, composition, deposition rate and optical properties were investigated. The compositions were controlled by changing the N2O/(N2O+N2) flow rate ratio (R). The refractive index was varied from 1.60 to 2.10, and the cutoff photon energy at 10% transmittance (Eg/10) from 5.1 to 7.0 eV as the R changed from 0 to 1.0. The Al O N films were composed mainly of a mixture of Al2O3 and AlN. An aluminum oxynitride phase was also identified at R=0.2 to 0.53. The Al O N films contained a (001)-oriented hexagonal AlN phase at R=0.025, and the films were amorphous at R>0.05.

  11. Ga-In liquid metal nanoparticles prepared by physical vapor deposition

    Directory of Open Access Journals (Sweden)

    Fan Yu

    2018-02-01

    Full Text Available Controlled synthesis and appropriate characterization of nanoscale particles of gallium-based liquid metals are critical to fulfilling their broad range of applications in the field of flexible, stretchable, and printable micro-/nanoelectronics. Herein, we report a new way to synthesize surfactant-free gallium-indium nanoparticles with controlled particle size on a variety of substrates through a facile physical vapor deposition method. It was found that with prolonged deposition time the liquid metal nanoparticles gradually grew from near-monodispersed small particles with a diameter of ~25 nm to bimodal distributed particles. A nucleation, growth, ripening and merging process was proposed to explain the observed evolution of particle size. Atomic force microscopy measurement indicates that the fabricated liquid metal nanoparticles demonstrate elastic deformation with a certain range of loads and the scanned particle size is dependent on the applied loads. We further investigated the gradual breaking process of the core-shell structured liquid metal nanoparticles, which was evidenced by multiple kinks on the force-separation curve. This work presents a new bottom-up approach to prepare nanoscale liquid metal particles and demonstrates that atomic force microscopy is a suitable technique to characterize the synthesized liquid metal nanoparticles. Keywords: Gallium-Indium alloy, Atomic force microscopy, Liquid metal, Nanoparticle

  12. Synthesis and characterization of graphenated carbon nanotubes on IONPs using acetylene by chemical vapor deposition method

    Science.gov (United States)

    Atchudan, Raji; Perumal, Suguna; Edison, Thomas Nesakumar Jebakumar Immanuel; Pandurangan, Arumugam; Lee, Yong Rok

    2015-11-01

    The graphenated carbon nanotubes (G-CNTs) were synthesized on monodisperse spherical iron oxide nanoparticles (IONPs) using acetylene as carbon precursor by simple chemical vapor deposition method. The reaction parameters such as temperature and flow of carbon source were optimized in order to achieve G-CNTs with excellent quality and quantity. Transmission electron microscopy (TEM) clearly illustrated that the graphene flakes are forming along the whole length on CNTs. The degree of graphitization was revealed by X-ray diffraction (XRD) analysis and Raman spectroscopic techniques. The intensity of D to G value was less than one which confirms the obtained G-CNTs have high degree of graphitization. The optimum reaction temperature for the IONPs to form metallic clusters which in turn lead to the formation of G-CNTs with high carbon deposition yield is at 900 °C. The TEM shows the CNTs diameter is 50 nm with foiled graphene flakes of diameter around 70 nm. Our results advocate for IONPs as a promising catalytic template for quantitative and qualitative productivity of nanohybrid G-CNTs. The produced G-CNTs with high degree of graphitization might be an ideal candidate for nanoelectronic application like super capacitors and so on.

  13. Atmospheric Pressure Spray Chemical Vapor Deposited CuInS2 Thin Films for Photovoltaic Applications

    Science.gov (United States)

    Harris, J. D.; Raffaelle, R. P.; Banger, K. K.; Smith, M. A.; Scheiman, D. A.; Hepp, A. F.

    2002-01-01

    Solar cells have been prepared using atmospheric pressure spray chemical vapor deposited CuInS2 absorbers. The CuInS2 films were deposited at 390 C using the single source precursor (PPh3)2CuIn(SEt)4 in an argon atmosphere. The absorber ranges in thickness from 0.75 - 1.0 micrometers, and exhibits a crystallographic gradient, with the leading edge having a (220) preferred orientation and the trailing edge having a (112) orientation. Schottky diodes prepared by thermal evaporation of aluminum contacts on to the CuInS2 yielded diodes for films that were annealed at 600 C. Solar cells were prepared using annealed films and had the (top down) composition of Al/ZnO/CdS/CuInS2/Mo/Glass. The Jsc, Voc, FF and (eta) were 6.46 mA per square centimeter, 307 mV, 24% and 0.35%, respectively for the best small area cells under simulated AM0 illumination.

  14. Physical vapor deposited films of a perylene derivative: supramolecular arrangement and thermal stability

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, Jose Diego; Alessio, Priscila; Silva, Matheus Rodrigues Medeiros; Aroca, Ricardo Flavio; Souza, Agda Eunice de; Constantino, Carlos Jose Leopoldo, E-mail: case@fct.unesp.br [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Presidente Prudente, SP (Brazil). Dept. de Fisica

    2017-07-15

    The analysis of supramolecular arrangement is essential to understand the role of this key factor on the optical and electrical properties of organic thin films. In this work, thin solid films of bis(phenethylimido) perylene (PhPTCD) fabricated using physical vapor deposition (PVD) technique (thermal evaporation), deposited simultaneously onto different substrates (Ag mirror, Ge, and quartz plates) contingent on the characterization technique. The main objective is to study the PhPTCD supramolecular arrangement and the thermal stability of this arrangement in PVD films. The ultraviolet-visible absorption reveals a controlled growth of the PVD films, and the micro-Raman scattering data show that the PhPTCD molecule is not thermally degraded in the conditions of these experiments. The microscopy also shows a homogeneous morphological surface of the PVD film at macro and micro scales, with molecular aggregates at nanoscale. Besides, the PVD film roughness does not follow substrate roughness. The X-ray diffraction indicates a crystalline structure for PhPTCD powder and an amorphous form for PhPTCD PVD film. The infrared absorption spectroscopy points to a preferential flat-on organization of the molecules in the PVD films. In addition, the annealing process (200 deg C for 20 minutes) does not affect the supramolecular arrangement of the PhPTCD PVD films. (author)

  15. Infrared and photoelectron spectroscopy study of vapor phase deposited poly (3-hexylthiophene)

    International Nuclear Information System (INIS)

    Wei Haoyan; Scudiero, L.; Eilers, Hergen

    2009-01-01

    Poly (3-hexylthiophene) (P3HT) was thermally evaporated and deposited in vacuum. Infrared spectroscopy was used to confirm that the thin films were indeed P3HT, and showed that in-situ thermal evaporation provides a viable route for contaminant-free surface/interface analysis of P3HT in an ultrahigh-vacuum (UHV) environment. Ultraviolet photoelectron spectroscopy (UPS) as well as X-ray photoelectron spectroscopy (XPS) experiments were carried out to examine the frontier orbitals and core energy levels of P3HT thin films vapor deposited in UHV on clean polycrystalline silver (Ag) surfaces. UPS spectra enable the determination of the vacuum shift at the polymer/metal interface, the valence band maximum (VBM), and the energy of the π-band of the overlayer film. The P3HT vacuum level decreased in contrast to that of the underlying Ag as the film thickness increased. XPS and UPS data confirmed the chemical integrity (stoichiometry) of the polymer at high coverage, as well as the shift of the C 1s and S 2p binding energy peaks and the secondary-electron edge with increasing film thickness, indicating that band bending is present at the P3HT/Ag interface and that the measured onset of the valence band is about 0.8 ± 0.05 eV relative to the Fermi level.

  16. Three-Dimensional Nanostructure Fabrication by Focused Ion Beam Chemical Vapor Deposition

    Science.gov (United States)

    Matsui, Shinji

    In this chapter, we describe three-dimensional nanostructure fabrication using 30 keV Ga+ focused ion beam chemical vapor deposition (FIB-CVD) and a phenanthrene (C14H10) source as a precursor. We also consider microstructure plastic art, which is a new field that has been made possible by microbeam technology, and we present examples of such art, including a "micro wine glass" with an external diameter of 2.75 μm and a height of 12 μm. The film deposited during such processes is diamond-like amorphous carbon, which has a Young's modulus exceeding 600 GPa, appearing to make it highly desirable for various applications. The production of three-dimensional nanostructures is also discussed. The fabrication of microcoils, nanoelectrostatic actuators, and 0.1 μm nanowiring - all potential components of nanomechanical systems - is explained. The chapter ends by describing the realization of nanoinjectors and nanomanipulators, novel nanotools for manipulating and analyzing subcellular organelles.

  17. Growth and electrical properties of AlOx grown by mist chemical vapor deposition

    Directory of Open Access Journals (Sweden)

    Toshiyuki Kawaharamura

    2013-03-01

    Full Text Available Aluminum oxide (AlOx thin films were grown using aluminum acetylacetonate (Al(acac3 as a source solute by mist chemical vapor deposition (mist CVD. The AlOx thin films grown at temperatures above 400°C exhibited a breakdown field (EBD over 6 MV/cm and a dielectric constant (κ over 6. It is suggested that residual OH bonding in the AlOx thin films grown at temperatures below 375°C caused degradation of the breakdown field (EBD. With FC type mist CVD, the reaction proceeded efficiently (Ea = 22–24 kJ/mol because the solvent, especially H2O, worked as a stronger oxygen source. The AlOx film could be grown at 450°C with a high deposition rate (23 nm/min and smooth surface (RMS = 1.5 nm. Moreover, the AlOx thin films grown by mist CVD had excellent practicality as insulators because the gate leakage current (IG of the oxide thin film transistor (TFT with an IGZO/AlOx stack was suppressed below 1 pA at a gate voltage (VG of 20 V.

  18. Physical vapor deposited films of a perylene derivative: supramolecular arrangement and thermal stability

    International Nuclear Information System (INIS)

    Fernandes, Jose Diego; Alessio, Priscila; Silva, Matheus Rodrigues Medeiros; Aroca, Ricardo Flavio; Souza, Agda Eunice de; Constantino, Carlos Jose Leopoldo

    2017-01-01

    The analysis of supramolecular arrangement is essential to understand the role of this key factor on the optical and electrical properties of organic thin films. In this work, thin solid films of bis(phenethylimido) perylene (PhPTCD) fabricated using physical vapor deposition (PVD) technique (thermal evaporation), deposited simultaneously onto different substrates (Ag mirror, Ge, and quartz plates) contingent on the characterization technique. The main objective is to study the PhPTCD supramolecular arrangement and the thermal stability of this arrangement in PVD films. The ultraviolet-visible absorption reveals a controlled growth of the PVD films, and the micro-Raman scattering data show that the PhPTCD molecule is not thermally degraded in the conditions of these experiments. The microscopy also shows a homogeneous morphological surface of the PVD film at macro and micro scales, with molecular aggregates at nanoscale. Besides, the PVD film roughness does not follow substrate roughness. The X-ray diffraction indicates a crystalline structure for PhPTCD powder and an amorphous form for PhPTCD PVD film. The infrared absorption spectroscopy points to a preferential flat-on organization of the molecules in the PVD films. In addition, the annealing process (200 deg C for 20 minutes) does not affect the supramolecular arrangement of the PhPTCD PVD films. (author)

  19. Low-Temperature Cu-Cu Bonding Using Silver Nanoparticles Fabricated by Physical Vapor Deposition

    Science.gov (United States)

    Wu, Zijian; Cai, Jian; Wang, Junqiang; Geng, Zhiting; Wang, Qian

    2018-02-01

    Silver nanoparticles (Ag NPs) fabricated by physical vapor deposition (PVD) were introduced in Cu-Cu bonding as surface modification layer. The bonding structure consisted of a Ti adhesive/barrier layer and a Cu substrate layer was fabricated on the silicon wafer. Ag NPs were deposited on the Cu surface by magnetron sputtering in a high-pressure environment and a loose structure with NPs was obtained. Shear tests were performed after bonding, and the influences of PVD pressure, bonding pressure, bonding temperature and annealing time on shear strength were assessed. Cu-Cu bonding with Ag NPs was accomplished at 200°C for 3 min under the pressure of 30 MPa without a post-annealing process, and the average bonding strength of 13.99 MPa was reached. According to cross-sectional observations, a void-free bonding interface with an Ag film thickness of around 20 nm was achieved. These results demonstrated that a reliable low-temperature short-time Cu-Cu bonding was realized by the sintering process of Ag NPs between the bonding pairs, which indicated that this bonding method could be a potential candidate for future ultra-fine pitch 3D integration.

  20. Characterization and modeling of tungsten nanoparticles generated by laser-assisted chemical vapor deposition

    International Nuclear Information System (INIS)

    Landstroem, L.; Kokavecz, J.; Lu, J.; Heszler, P.

    2004-01-01

    Tungsten nanoparticles were generated by photolytical (UV) laser-activated chemical vapor deposition from WF 6 /H 2 /Ar gas mixture. Emission spectroscopy of thermal radiation allowed temperature determination of the nanoparticles while varying the laser fluence. A model including known cooling mechanisms was used to calculate the laser-induced temperature as a function of time and laser fluence, where the only fitting parameter was the absorption efficiency of the particles, obtained from measured temperatures. Size decrease of the particles due to evaporation was modeled at different laser fluences, and connected to size-distribution measurements from transmission electron microscopy micrographs, where a maximum geometric mean diameter (for the experimental conditions used) of 10 nm was observed at a laser fluence of ∼120 mJ/cm2. Measurements and the model calculations showed that the laser-excited particles reached the melting temperature of tungsten at ∼95 mJ/cm2. Above ∼130 mJ/cm2, very high rates of evaporation of W atoms were found, resulting in a decrease in size of the deposited particles. Crystalline, metastable β-W nanoparticles were found above ∼100 mJ/cm2 by both electron and x-ray diffraction. Below fluences of ∼100 mJ/cm2, i.e., corresponding to the value necessary for melting, amorphous nanoparticles were obtained

  1. Development of vapor deposited silica sol-gel particles for use as a bioactive materials system.

    Science.gov (United States)

    Snyder, Katherine L; Holmes, Hallie R; VanWagner, Michael J; Hartman, Natalie J; Rajachar, Rupak M

    2013-06-01

    Silica-based sol-gel and bioglass materials are used in a variety of biomedical applications including the surface modification of orthopedic implants and tissue engineering scaffolds. In this work, a simple system for vapor depositing silica sol-gel nano- and micro-particles onto substrates using nebulizer technology has been developed and characterized. Particle morphology, size distribution, and degradation can easily be controlled through key formulation and manufacturing parameters including water:alkoxide molar ratio, pH, deposition time, and substrate character. These particles can be used as a means to rapidly modify substrate surface properties, including surface hydrophobicity (contact angle changes >15°) and roughness (RMS roughness changes of up to 300 nm), creating unique surface topography. Ions (calcium and phosphate) were successfully incorporated into particles, and induced apatitie-like mineral formation upon exposure to simulated body fluid Preosteoblasts (MC3T3) cultured with these particles showed up to twice the adhesivity within 48 h when compared to controls, potentially indicating an increase in cell proliferation, with the effect likely due to both the modified substrate properties as well as the release of silica ions. This novel method has the potential to be used with implants and tissue engineering materials to influence cell behavior including attachment, proliferation, and differentiation via cell-material interactions to promote osteogenesis. Copyright © 2012 Wiley Periodicals, Inc.

  2. In situ preparation of nickel/carbon core–shell structure by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Fuyang [Key Laboratory of Advanced Technologies of Materials, Ministry of Education of China, Superconductivity and New Energy R and D Center, Southwest Jiaotong University, Chengdu 610031 (China); Jiang, Qi, E-mail: jiangqi66@163.com [Key Laboratory of Advanced Technologies of Materials, Ministry of Education of China, Superconductivity and New Energy R and D Center, Southwest Jiaotong University, Chengdu 610031 (China); Fang, Yuan; Ban, Shengguang; Ou, Shisheng; Qian, Hongxia [Key Laboratory of Advanced Technologies of Materials, Ministry of Education of China, Superconductivity and New Energy R and D Center, Southwest Jiaotong University, Chengdu 610031 (China); Zhao, Yong [School of Materials Science and Engineering, University of New South Wales, Sydney, 2052 NSW (Australia)

    2013-10-15

    Nickel/carbon core–shell structure with uniform diameter has been synthesized by galvanostatic electrodeposition nickel on its surface followed by chemical vapor deposition. We proposed the growth mechanism of the core–shell structure that the precipitation of carbon from metal catalysts during the high temperature growth period lifts up metal particles leading to the formation of core–shell structure or carbon nanotubes with respect to the diameter of catalyst particles. The substrate with deposited nickel was characterized by optical microscope. The elements and features of the substrate were studied by energy dispersive X-ray spectroscopy and X-ray diffraction respectively. The morphology of the resulting material was examined by field emitting scanning electron microscopy. In addition, the electrochemical performance of the core–shell structure modified electrodes was also investigated. The result shows that electrodes modified with core structure have better electrochemical property than the bare electrodes in the [Fe(CN){sub 6}]{sup 3−}/[Fe(CN){sub 6}]{sup 4−} solution at a scan rate of 20 mV s{sup −1}.

  3. Morphological Evolution of a-GaN on r-Sapphire by Metalorganic Chemical Vapor Deposition

    International Nuclear Information System (INIS)

    Sang Ling; Liu Jian-Ming; Xu Xiao-Qing; Wang Jun; Zhao Gui-Juan; Liu Chang-Bo; Gu Cheng-Yan; Liu Gui-Peng; Wei Hong-Yuan; Liu Xiang-Lin; Yang Shao-Yan; Zhu Qin-Sheng; Wang Zhan-Guo

    2012-01-01

    The morphological evolution of a-GaN deposited by metalorganic chemical vapor deposition (MOCVD) on r-sapphire is studied. The influences of V/III ratio and growth temperature on surface morphology are investigated. V-pits and stripes are observed on the surface of a-GaN grown at 1050°C and 1100°C, respectively. The overall orientation and geometry of V-pits are uniform and independent on the V/III molar ratio in the samples grown at 1050°C, while in the samples grown at 1100°C, the areas of stripes decrease with the adding of V/III ratio. We deduce the origin of V-pits and stripes by annealing the buffer layers at different temperatures. Because of the existence of inclined (101-bar1) facets, V-pits are formed at 1050°C. The (101-bar1) plane is an N terminated surface, which is metastable at higher temperature, so stripes instead of V-pits are observed at 1100°C. Raman spectra suggest that the growth temperature of the first layer in the two-step process greatly affects the strain of the films. Hence, to improve the growth temperature of the first layer in the two-step method may be an effective way to obtain high quality a-GaN film on r-sapphire. (condensed matter: structure, mechanical and thermal properties)

  4. Chemical Vapor Deposition of ?-Boron Layers on Silicon for Controlled Nanometer-Deep p+n Junction Formation

    NARCIS (Netherlands)

    Sarubbi, F.; Scholtes, T.L.M.; Nanver, L.K.

    2009-01-01

    Nanometer-thick amorphous boron (?-B) layers were formed on (100) Si during exposure to diborane (B2H6) in a chemical vapor deposition (CVD) system, either at atmospheric or reduced pressures, at temperatures down to 500°C. The dependence of the growth mechanism on processing parameters was

  5. Plasma-enhanced chemical vapor deposited silicon oxynitride films for optical waveguide bridges for use in mechanical sensors

    DEFF Research Database (Denmark)

    Storgaard-Larsen, Torben; Leistiko, Otto

    1997-01-01

    In this paper the influence of RF power, ammonia flow, annealing temperature, and annealing time on the optical and mechanical properties of plasma-enhanced chemically vapor deposited silicon oxynitride films, is presented. A low refractive index (1.47 to 1.48) film having tensile stress has been...

  6. Vertically aligned carbon nanotube field emitter arrays with Ohmic base contact to silicon by Fe-catalyzed chemical vapor deposition

    NARCIS (Netherlands)

    Morassutto, M.; Tiggelaar, Roald M.; Smithers, M.A.; Smithers, M.A.; Gardeniers, Johannes G.E.

    2016-01-01

    Abstract In this study, dense arrays of aligned carbon nanotubes are obtained by thermal catalytic chemical vapor deposition, using Fe catalyst dispersed on a thin Ta layer. Alignment of the carbon nanotubes depends on the original Fe layer thickness from which the catalyst dispersion is obtained by

  7. Synthesis of inorganic membranes by vapor deposition processes: Theory and experiments

    Science.gov (United States)

    Xomeritakis, George

    In this work, theoretical and experimental studies are presented regarding the application of Chemical Vapor Deposition (CVD) and Magnetron Sputtering for preparation of different types of inorganic membranes in/on porous supports. In the theoretical part, semi-analytical solutions of mathematical models that describe CVD in porous media are first developed, considering introduction of vapor precursors from either one side or opposite sides of a porous support. These solutions describe the deposition characteristics and pore narrowing kinetics as explicit functions of the various process parameters (precursors concentrations and diffusivities, reaction kinetics) and support properties (pore size, thickness and porosity). The extention of these solutions for the purpose of predicting macroscopic properties of inorganic membranes, of relevance to their application in gas separations, such as permeance, pore size (distribution) and selectivity is also demonstrated. The feasibility of CVD for preparing novel nanocrystalline ceramic-supported palladium membranes using different precursors and reaction schemes is demonstrated in this work. Thin (0.5-5 mum), nanocrystalline (15-50 nm grain size) Pd membranes can be prepared inside pores or on the surface of ultrafiltration ceramic supports, using volatile inorganic or metallorganic palladium salts and hydrogen as precursors, under proper experimental conditions. These membranes exhibit satisfactory permselectivity only when Pd is deposited in the form of a metal layer on the surface of the support. For the first time, synthesis of submicron-thick, ceramic-supported Pd-based metallic membranes with substantial permselectivity at elevated temperatures is demonstrated in this work, using the magnetron sputtering technique. The effect of synthesis conditions on metallic membrane texture and permeation properties is also systematically investigated. For Pd-based metallic membranes coated to a thickness of 0.1-1.5 mum on the

  8. Modeling of gas-phase chemistry in the chemical vapor deposition of polysilicon in a cold wall system

    Energy Technology Data Exchange (ETDEWEB)

    Toprac, A.J.; Edgar, T.F.; Trachtenberg, I. (Univ. of Texas, Austin, TX (United States). Dept. of Chemical Engineering)

    1993-06-01

    The relative contribution of gas-phase chemistry to deposition processes is an important issue both from the standpoint of operation and modeling of these processes. In polysilicon deposition from thermally activated silane in a cold wall rapid thermal chemical vapor deposition (RTCVD) system, the relative contribution of gas-phase chemistry to the overall deposition rate was examined by a mass-balance model. Evaluating the process at conditions examined experimentally, the model indicated that gas-phase reactions may be neglected to good accuracy in predicting polysilicon deposition rate. The model also provided estimates of the level of gas-phase generated SiH[sub 2] associated with deposition on the cold-process chamber walls.

  9. Rapid growth of zinc oxide nanobars in presence of electric field by physical vapor deposition

    Science.gov (United States)

    Jouya, Mehraban; Taromian, Fahime; Siami, Simin

    2017-12-01

    In this contribution, electric field has some effects to increase growth for specific time duration on zinc oxide (ZnO) nanobars. First, the zinc (Zn) thin film has been prepared by 235,000 V/m electric field assisted physical vapor deposition (PVD) at vacuum of 1.33 × 10-5 mbar. Second, strong electric field of 134,000 V/m has been used in ambient for growing ZnO nanobars in term of the time include 2.5 and 10 h. The performances of the ZnO nanostructure in absence and presence of electric field have been determined by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results of XRD analysis showed that ZnO has a hexagonal bars structure and a strongly preferred (101) orientation which is strongest than without applying electric field. SEM analysis revealed that physical vapored ZnO thin film in presence of electric field are densely packed with uniform morphological, thinner and denser in distribution. Electric field effect for ZnO growth in 2.5 h is better than it in the 2.5 h without electric field but by passing the time the media influence has good power almost as same as electric field. Through this electric field in PVD, the compact and uniform Zn film has been achieved which is less diameter than ordinary PVD method. Finally, we carry out a series of experiments to grow different-orientation ZnO nanobars with less than 100 nm in diameter, which are the time saving process in base of PVD ever reported. Therefore, the significant conclusion in usage electric field is reducing time of growth.

  10. Direct Fabrication of Carbon Nanotubes STM Tips by Liquid Catalyst-Assisted Microwave Plasma-Enhanced Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    Fa-Kuei Tung

    2009-01-01

    Full Text Available Direct and facile method to make carbon nanotube (CNT tips for scanning tunneling microscopy (STM is presented. Cobalt (Co particles, as catalysts, are electrochemically deposited on the apex of tungsten (W STM tip for CNT growth. It is found that the quantity of Co particles is well controlled by applied DC voltage, concentration of catalyst solution, and deposition time. Using optimum growth condition, CNTs are successfully synthesized on the tip apex by catalyst-assisted microwave-enhanced chemical vapor deposition (CA-MPECVD. A HOPG surface is clearly observed at an atomic scale using the present CNT-STM tip.

  11. Van der Waals epitaxial growth of MoS2 on SiO2/Si by chemical vapor deposition

    KAUST Repository

    Cheng, Yingchun

    2013-01-01

    Recently, single layer MoS2 with a direct band gap of 1.9 eV has been proposed as a candidate for two dimensional nanoelectronic devices. However, the synthetic approach to obtain high-quality MoS2 atomic thin layers is still problematic. Spectroscopic and microscopic results reveal that both single layers and tetrahedral clusters of MoS2 are deposited directly on the SiO2/Si substrate by chemical vapor deposition. The tetrahedral clusters are mixtures of 2H- and 3R-MoS2. By ex situ optical analysis, both the single layers and tetrahedral clusters can be attributed to van der Waals epitaxial growth. Due to the similar layered structures we expect the same growth mechanism for other transition-metal disulfides by chemical vapor deposition. © 2013 The Royal Society of Chemistry.

  12. Fabrication of 100 A class, 1 m long coated conductor tapes by metal organic chemical vapor deposition and pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Selvamanickam, V.; Lee, H.G.; Li, Y.; Xiong, X.; Qiao, Y.; Reeves, J.; Xie, Y.; Knoll, A.; Lenseth, K

    2003-10-15

    SuperPower has been scaling up YBa{sub 2}Cu{sub 3}O{sub x}-based second-generation superconducting tapes by techniques such as pulsed laser deposition (PLD) using industrial laser and metal organic chemical vapor deposition (MOCVD). Both techniques offer advantage of high deposition rates, which is important for high throughput. Using highly-polished substrates produced in a reel-to-reel polishing facility and buffer layers deposited in a pilot ion beam assisted deposition facility, meter-long second-generation high temperature superconductor tapes have been produced. 100 A class, meter-long coated conductor tapes have been reproducibly demonstrated in this work by both MOCVD and PLD. The best results to date are 148 A over 1.06 m by MOCVD and 135 A over 1.1 m by PLD using industrial laser.

  13. Chemical vapor deposition of aluminide coatings on iron, nickel and superalloys

    International Nuclear Information System (INIS)

    John, John T.; De, P.K.; Dubey, Vivekanand; Srinivasa, Raman

    2009-08-01

    Aluminide coatings are a class of intermetallic coatings applied on nickel and cobalt base superalloys and steels to protect them from different forms of environmental degradation at high temperatures. In this report a CVD system that can produce the aluminide coatings on iron, nickel and nickel base alloys has been described and the result of chemical vapor deposition of aluminide coatings on iron specimens, their characterization, and property evaluation have been presented. The CVD system consists of an AlCl 3 bath, a stainless steel retort as a hot-wall reacto, cold traps and vacuum system. Aluminium chloride vapor was carried in a stream of hydrogen gas at a flow rate of 150 SCCM (standard cubic centimeter per minute) into the CVD reactor maintained in the temperature range of 1173 - 1373 K and at a pressure of 1.33 kPa (10 Torr). Aluminum deposition takes place from aluminium subchlorides produced by reaction between AlCl 3 and pure aluminum kept in the CVD reactor. The aluminum diffuses into the iron samples and iron aluminide phases are formed at the surface. The coatings were shining bright and showed good adherence to the substrate. The coatings consisted of FeAl phase over a wide range of experimental conditions. The growth kinetics of the coating followed a parabolic rate law and the mean activation energy was 212 ±16 kJ/mol. Optical microscopic studies on the transverse section of the coating showed that the aluminide coating on iron consisted of two layers. The top layer had a thickness in the range of 20-50 μm, and the under layer had thickness ranging from 35 to 250 μm depending on coating temperature in two hours. The thickness of the aluminide layer increased with coating duration and temperature. Electron microprobe studies (EPMA) showed that the aluminum concentration decreased steadily as distance from the surface increased. TEM studies showed that the outer most layer had a B2 order (of the FeAl phase), which extended even into the under

  14. Reduced-pressure chemical vapor deposition of boron-doped Si and Ge layers

    International Nuclear Information System (INIS)

    Bogumilowicz, Y.; Hartmann, J.M.

    2014-01-01

    We have studied the in-situ boron (B) doping of germanium (Ge) and silicon (Si) in Reduced Pressure-Chemical Vapor Deposition. Three growth temperatures have been investigated for the B-doping of Ge: 400, 600 and 750 °C at a constant growth pressure of 13300 Pa (i.e. 100 Torr). The B concentration in the Ge:B epilayer increases linearly with the diborane concentration in the gaseous phase. Single-crystalline Ge:B layers with B concentrations in-between 9 ∙ 10 17 and 1 ∙ 10 20 cm −3 were achieved. For the in-situ B doping of Si at 850 °C, two dichlorosilane mass flow ratios (MFR) have been assessed: F[SiH 2 Cl 2 ]/F[H 2 ] = 0.0025 and F[SiH 2 Cl 2 ]/F[H 2 ] = 0.0113 at a growth pressure of 2660 Pa (i.e. 20 Torr). Linear boron incorporation with the diborane concentration in the gas phase has been observed and doping levels in-between 3.5 ∙ 10 17 and 1 ∙ 10 20 cm −3 were achieved. We almost kept the same ratio of B versus Si atoms in the gas phase and in the Si epilayer. By contrast, roughly half of the B atoms present in the gas phase were incorporated in the Ge:B layers irrespective of the growth temperature. X-Ray Diffraction (XRD) allowed us to extract from the angular position of the Ge:B layer diffraction peak the substitutional B concentration. Values close to the B concentrations obtained by 4-probe resistivity measurements were obtained. Ge:B layers were smooth (< 1 m root mean square roughness associated with 20 × 20 μm 2 Atomic Force Microscopy images). Only for high F[B 2 H 6 ]/F[GeH 4 ] MFR (3.2 10 −3 ) did the Ge:B layers became rough; they were however still mono-crystalline (XRD). Above this MFR value, Ge:B layers became polycrystalline. - Highlights: • Boron doping of germanium and silicon in Reduced Pressure-Chemical Vapor Deposition • Linear boron incorporation in Ge:B and Si:B with the diborane flow • Single-crystal Ge:B layers with B concentrations in-between 9 ∙ 10 17 and 1 ∙ 10 20 cm −3 • Single-crystal Si

  15. Mechanisms controlling temperature dependent mechanical and electrical behavior of SiH4 reduced chemically vapor deposited W

    International Nuclear Information System (INIS)

    Joshi, R.V.; Prasad, V.; Krusin-Elbaum, L.; Yu, M.; Norcott, M.

    1990-01-01

    The effects of deposition temperature on growth, composition, structure, adhesion properties, stress, and resistivity of chemically vapor deposited W deposited purely by SiH 4 reduction of WF 6 are discussed. At lower deposition temperatures, due to incomplete Si reduction reaction, a small amount of Si is incorporated in the film. This elemental Si in W is responsible for the observed high stresses and high resistivities over a wide temperature range. With the increase in the deposition temperature, the conversion of incorporated Si as well as the initial Si reduction are taking place, stimulating increased grain growth and thereby relieving stress and reducing resistivity. The optimum values for stress and resistivity are achieved around 500 degree C, as Si content is at its minimum. At higher temperatures the reaction between residual Si and W, is the prime cause of resistivity increase

  16. Effects of plasma-enhanced chemical vapor deposition (PECVD) on the carrier lifetime of Al2O3 passivation stack

    Science.gov (United States)

    Cho, Kuk-Hyun; Cho, Young Joon; Chang, Hyo Sik; Kim, Kyung-Joong; Song, Hee Eun

    2015-09-01

    We investigated the effect on the minority carrier lifetime of atomic layer deposition (ALD) Al2O3 passivation by a plasma-enhanced chemical vapor deposition (PECVD) SiON layer in Si/Al2O3/SiON-passivated structure. The lifetime variation of the Al2O3/SiON stack layer was found to depend on both the plasma power and the deposition temperature during the PECVD SiON process and to show better thermal stability than the Al2O3/SiNx:H stack under the same deposition conditions. The lifetime after a high-temperature firing process was improved dramatically at the PECVD deposition temperature of 200 °C. Our results provide a significant clue to reason for the improvement of the passivation performance for passivated emitter and rear contact (PERC) silicon solar cells.

  17. Chemical vapor deposition of metal nitrides, phosphides and arsenides. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, D.M. [Univ. of Houston, TX (United States). Dept. of Chemistry

    1994-03-01

    The author recently reported that dialkylamido complexes are promising precursors to nitride thin films. On this basis it was reasoned that transition metal and main group disilazide complexes in which the silicon has dialkylamido substituents are potential precursors to ternary silicon nitride films. Bulky disilazide ligands are known to stabilize main group and transition metal complexes with low coordination numbers. Reaction of dimethylamine with Cl{sub 3}SiN(H)SiMe{sub 3} in hexane solution at 25{degrees}C gave the bulky disilazane [(Me{sub 2}N){sub 3}Si]N(h)SiMe{sub 3} (1) in 73% yield. Reaction of (1) with n-butyl lithium in benzene at 0{degrees}C produced [(Me{sub 2}N){sub 3}Si]N(Li)SiMe{sub 3} in 82% yield. LiN[Si(NMe{sub 2}){sub 3}]{sub 2} was chemically prepared in 92% yield and was converted to the amine with 83% yield. The author examined the use of amido precursors for main group oxide thin films. Sn(NMe{sub 2}){sub 4} and Si(NMe{sub 2}){sub 4} react with oxygen in an atmospheric pressure chemical vapor deposition reactor to give SnO{sub 2} and SiO{sub 2} films, respectively. The films were deposited on quartz, silicon, and glass at substrate temperatures of 250--400 {degrees}C. The results of the characterizations of the films and compounds are presented in this report.

  18. Synthesis of nanocrystalline Cu1-xTax composites using physical vapor deposition

    International Nuclear Information System (INIS)

    Savage, H.S.; Wang, H.; Rigsbee, J.M.

    1993-01-01

    Physical vapor deposition (PVD) processes provide the capability for creating new types of metallic, ceramic, and polymeric composites by allowing atomic-scale engineering of structure and chemistry. Because PVD processes provide the capacity for circumventing thermodynamic factors, such as solubility limits, it is possible to produce nonequilibrium alloys and materials with unique mixtures of phases. The ease by which PVD produces materials with nanocrystalline microstructures is an added benefit of these processes. This paper describes ion plating, a plasma-assisted PVD process, and its application for the development of a new class of nanoscale dispersion-strengthened Cu 1-x Ta x alloys. Copper-tantalum was selected as a model system because the extensive liquid miscibility gap and nearly zero mutual solid solubilities prevent creation of Cu-Ta alloys by conventional or rapid solidification processes. Microchemical analyses of the family of Cu 1-x Ta x alloys indicate that PVD can produce materials with any desired level of Ta. X-ray diffraction and transmission electron microscopy analyses show that the as-deposited microstructures consist generally of a Cu matrix supersaturated with Ta and containing a uniform dispersion of Ta particles with diameters below 10 nm. The Ta particles are face centered cubic (exceptionally large Ta particles, larger than ∼100 nm, are body centered cubic) and are oriented identically with the Cu matrix. Particle coarsening studies, at temperatures up to 900C and for times as long as 100 hours, indicate an extreme degree of microstructural stability. The Ta particles also appear highly effective at maintaining a submicron Cu matrix grain size even after annealing at 900C

  19. Fabrication of layered self-standing diamond film by dc arc plasma jet chemical vapor deposition

    International Nuclear Information System (INIS)

    Chen, G. C.; Dai, F. W.; Li, B.; Lan, H.; Askari, J.; Tang, W. Z.; Lu, F. X.

    2007-01-01

    Layered self-standing diamond films, consisting of an upper layer, buffer layer, and a lower layer, were fabricated by fluctuating the ratio of methane to hydrogen in high power dc arc plasma jet chemical vapor deposition. There were micrometer-sized columnar diamond crystalline grains in both upper layer and lower layer. The size of the columnar diamond crystalline grains was bigger in the upper layer than that in the lower layer. The orientation of the upper layer was (110), while it was (111) for the lower layer. Raman results showed that no sp 3 peak shift was found in the upper layer, but it was found and blueshifted in the lower layer. This indicated that the internal stress within the film body could be tailored by this layered structure. The buffer layer with nanometer-sized diamond grains formed by secondary nucleation was necessary in order to form the layered film. Growth rate was over 10 μm/h in layered self-standing diamond film fabrication

  20. Hierarchical chrysanthemum-flower-like carbon nanomaterials grown by chemical vapor deposition

    Science.gov (United States)

    Ding, Er-Xiong; Geng, Hong-Zhang; Wang, Jing; Luo, Zhi-Jia; Li, Guangfen; Wang, Wen-Yi; Li, Lin-Ge; Yang, Hai-Jie; Da, Shi-Xun; Wang, Jie; Jiang, Hua; Kauppinen, Esko I.

    2016-02-01

    Novel hierarchical chrysanthemum-flower-like carbon nanomaterials (CFL-CNMs) were synthesized by thermal chemical vapor deposition based on acetylene decomposition. A scanning electron microscope and a transmission electron microscope were employed to observe the morphology and structure of the unconventional nanostructures. It is found that the CFL-CNMs look like a blooming chrysanthemum with a stem rather than a spherical flower. The carbon flower has an average diameter of 5 μm, an average stem diameter of 150 nm, branch diameters ranging from 20 to 70 nm, and branch lengths ranging from 0.5 to 3 μm. The morphologies of the CFL-CNMs are unlike any of those previously reported. Fishbone-like carbon nanofibers with a spindle-shaped catalyst locating at the tip can also be found. Furthermore, the catalyst split was proposed to elucidate the formation mechanism of CFL-CNMs. A large and glomerate catalyst particle at the tip of the carbon nanofiber splits into smaller catalyst particles which are catalytic-active points for branch formation, resulting in the formation of CFL-CNMs.

  1. Feasibility study of the microforming combined with selective chemical vapor deposition

    Directory of Open Access Journals (Sweden)

    Koshimizu Kazushi

    2015-01-01

    Full Text Available Microforming has been received much attention in the recent decades due to the wide use of microparts in electronics and medical applications. For the further functionalization of these micro devices, high functional surfaces with noble metals and nanomaterials are strongly required in bio- and medical fields, such as bio-sensors. To realize an efficient manufacturing process, which can deform the submillimeter scale bulk structure and can construct the micro to nanometer scale structures in one process, the present study proposes a combined process of microforming for metal foils with a selective chemical vapor deposition (SCVD on the active surfaces of the working material. To demonstrate feasibility of this proposed process, feasibility of SCVD of functional materials onto active surfaces of titanium (Ti was investigated. CVD of iron (Fe and carbon nanotubes (CNTs which construct CNTs on the patterned surfaces of the active Ti and non-active Ti oxidation layers were conducted. Ti thin films on silicon substrate and Fe were used as working materials and functional materials respectively. CNTs were grown only on the Ti surface. Consequently, selectivity of the active surface of Ti to the synthesis of Fe particles in CVD was confirmed.

  2. Selective Chemical Vapor Deposition Growth of Cubic FeGe Nanowires That Support Stabilized Magnetic Skyrmions.

    Science.gov (United States)

    Stolt, Matthew J; Li, Zi-An; Phillips, Brandon; Song, Dongsheng; Mathur, Nitish; Dunin-Borkowski, Rafal E; Jin, Song

    2017-01-11

    Magnetic skyrmions are topologically stable vortex-like spin structures that are promising for next generation information storage applications. Materials that host magnetic skyrmions, such as MnSi and FeGe with the noncentrosymmetric cubic B20 crystal structure, have been shown to stabilize skyrmions upon nanostructuring. Here, we report a chemical vapor deposition method to selectively grow nanowires (NWs) of cubic FeGe out of three possible FeGe polymorphs for the first time using finely ground particles of cubic FeGe as seeds. X-ray diffraction and transmission electron microscopy (TEM) confirm that these micron-length NWs with ∼100 nm to 1 μm diameters have the cubic B20 crystal structure. Although Fe 13 Ge 8 NWs are also formed, the two types of NWs can be readily differentiated by their faceting. Lorentz TEM imaging of the cubic FeGe NWs reveals a skyrmion lattice phase under small applied magnetic fields (∼0.1 T) at 233 K, a skyrmion chain state at lower temperatures (95 K) and under high magnetic fields (∼0.4 T), and a larger skyrmion stability window than bulk FeGe. This synthetic approach to cubic FeGe NWs that support stabilized skyrmions opens a route toward the exploration of new skyrmion physics and devices based on similar nanostructures.

  3. Radiative recombination mechanisms in CdTe thin films deposited by elemental vapor transport

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Shamara [Department of Electrical Engineering, University of South Florida, 4202 East Fowler Ave, Tampa, FL 33620 (United States); Vatavu, Sergiu, E-mail: svatavu@usm.md [Department of Electrical Engineering, University of South Florida, 4202 East Fowler Ave, Tampa, FL 33620 (United States); Faculty of Physics and Engineering, Moldova State University, 60 A. Mateevici str., Chisinau, MD-2009, Republic of Moldova (Moldova, Republic of); Evani, Vamsi; Khan, Md; Bakhshi, Sara; Palekis, Vasilios [Department of Electrical Engineering, University of South Florida, 4202 East Fowler Ave, Tampa, FL 33620 (United States); Rotaru, Corneliu [Faculty of Physics and Engineering, Moldova State University, 60 A. Mateevici str., Chisinau, MD-2009, Republic of Moldova (Moldova, Republic of); Ferekides, Chris [Department of Electrical Engineering, University of South Florida, 4202 East Fowler Ave, Tampa, FL 33620 (United States)

    2015-05-01

    A photoluminesence (PL) study of the radiative recombination mechanisms for CdTe films deposited under different Cd and Te overpressure by elemental vapor transport is presented. The experiment and analysis have been carried out in the temperature range of 12-130 K. The intensity of the PL laser excitation beam was varied by two orders of magnitude. It has been established that the bands in the 1.47-1.50 eV are determined by transitions involving shallow D and A states and the 1.36x-1.37x eV band is due to band to level transitions. Deep transitions at 1.042 eV and 1.129 eV are due to radiative transitions to levels determined by CdTe native defects. - Highlights: • Photoluminescense (PL) of CdTe thin films is present in the 0.8-1.6 eV spectral region. • High intensity excitonic peaks are among the main radiative paths. • Radiative transitions at 1.36x eV are assisted by dislocations caused levels. • Extremal Cd/Te overpressure ratios enhance PL for 1.497 eV, 1.486 eV, 1.474 eV bands. • PL intensity reaches its max value for the 0.45 and 1.25 Cd/Te overpressure ratios.

  4. Vapor phase polymerization deposition of conducting polymer/graphene nanocomposites as high performance electrode materials.

    Science.gov (United States)

    Yang, Yajie; Li, Shibin; Zhang, Luning; Xu, Jianhua; Yang, Wenyao; Jiang, Yadong

    2013-05-22

    In this paper, we report chemical vapor phase polymerization (VPP) deposition of novel poly(3,4-ethylenedioxythiophene) (PEDOT)/graphene nanocomposites as solid tantalum electrolyte capacitor cathode films. The PEDOT/graphene films were successfully prepared on porous tantalum pentoxide surface as cathode films through the VPP procedure. The results indicated that the high conductivity nature of PEDOT/graphene leads to the decrease of cathode films resistance and contact resistance between PEDOT/graphene and carbon paste. This nanocomposite cathode film based capacitor showed ultralow equivalent series resistance (ESR) ca. 12 mΩ and exhibited better capacitance-frequency performance than the PEDOT based capacitor. The leakage current investigation revealed that the device encapsulation process does not influence capacitor leakage current, indicating the excellent mechanical strength of PEDOT-graphene films. The graphene showed a distinct protection effect on the dielectric layer from possible mechanical damage. This high conductivity and mechanical strength graphene based conducting polymer nanocomposites indicated a promising application future for organic electrode materials.

  5. Synthesis-condition dependence of carbon nanotube growth by alcohol catalytic chemical vapor deposition method

    Directory of Open Access Journals (Sweden)

    Nobuhito Inami et al

    2007-01-01

    Full Text Available We report the dependence of growth yield of single-walled carbon nanotubes (SWNTs on heat-treatment time and catalyst film thickness by the alcohol catalytic chemical vapor deposition method. Three types of heat-treatment, synthesis of 30 min, synthesis of 30 min after annealing of 30 min, and synthesis of 60 min, were investigated. Thickness of Co catalyst film was varied from 1 to 10 nm. In the case of thinner Co film less than 3 nm, long synthesis time of 60 min is favorable for the effective SWNT growth, because of the small amount of Co catalyst. In the case of thicker Co film more than 3 nm, an amount of grown SWNTs by 30 min synthesis after 30 min annealing and by 60 min synthesis was much higher than that by 30 min synthesis without annealing, showing that total heat-treatment time of 60 min is important for the SWNT growth. Results suggest that the conversion from the thicker film of Co to nano-particle which acts as catalyst takes place during the first 30 min.

  6. Chemical vapor deposition diamond based multilayered radiation detector: Physical analysis of detection properties

    International Nuclear Information System (INIS)

    Almaviva, S.; Marinelli, Marco; Milani, E.; Prestopino, G.; Tucciarone, A.; Verona, C.; Verona-Rinati, G.; Angelone, M.; Pillon, M.; Dolbnya, I.; Sawhney, K.; Tartoni, N.

    2010-01-01

    Recently, solid state photovoltaic Schottky diodes, able to detect ionizing radiation, in particular, x-ray and ultraviolet radiation, have been developed at the University of Rome 'Tor Vergata'. We report on a physical and electrical properties analysis of the device and a detailed study of its detection capabilities as determined by its electrical properties. The design of the device is based on a metal/nominally intrinsic/p-type diamond layered structure obtained by microwave plasma chemical vapor deposition of homoepitaxial single crystal diamond followed by thermal evaporation of a metallic contact. The device can operate in an unbiased mode by using the built-in potential arising from the electrode-diamond junction. We compare the expected response of the device to photons of various energies calculated through Monte Carlo simulation with experimental data collected in a well controlled experimental setup i.e., monochromatic high flux x-ray beams from 6 to 20 keV, available at the Diamond Light Source synchrotron in Harwell (U.K.).

  7. Early evaluation of potential environmental impacts of carbon nanotube synthesis by chemical vapor deposition.

    Science.gov (United States)

    Plata, Desirée L; Hart, A John; Reddy, Christopher M; Gschwend, Philip M

    2009-11-01

    The carbon nanotube (CNT) industry is expanding rapidly, yet little is known about the potential environmental impacts of CNT manufacture. Here, we evaluate the effluent composition of a representative multiwalled CNT synthesis by catalytic chemical vapor deposition (CVD) in order to provide data needed to design strategies for mitigating any unacceptable emissions. During thermal pretreatment of the reactant gases (ethene and H(2)), we found over 45 side-products were formed, including methane, volatile organic compounds (VOCs), and polycyclic aromatic hydrocarbons (PAHs). This finding suggests several environmental concerns with the existing process, including potential discharges of the potent greenhouse gas, methane (up to 1.7%), and toxic compounds such as benzene and 1,3-butadiene (up to 36000 ppmv). Extrapolating these laboratory-scale data to future industrial CNT production, we estimate that (1) contributions of atmospheric methane will be negligible compared to other existing sources and (2) VOC and PAH emissions may become important on local scales but will be small when compared to national industrial sources. As a first step toward reducing such unwanted emissions, we used continuous in situ measures of CNT length during growth and sought to identify which thermally generated compounds correlated with CNT growth rate. The results suggested that, in future CNT production approaches, key reaction intermediates could be delivered to the catalyst without thermal treatment. This would eliminate the most energetically expensive component of CVD synthesis (heating reactant gases), while reducing the formation of unintended byproducts.

  8. Preparation of Ti species coating hydrotalcite by chemical vapor deposition for photodegradation of azo dye.

    Science.gov (United States)

    Xiao, Gaofei; Zeng, HongYan; Xu, Sheng; Chen, ChaoRong; Zhao, Quan; Liu, XiaoJun

    2017-10-01

    TiO 2 in anatase crystal phase is a very effective catalyst in the photocatalytic oxidation of organic compounds in water. To improve its photocatalytic activity, the Ti-coating MgAl hydrotalcite (Ti-MgAl-LDH) was prepared by chemical vapor deposition (CVD) method. Response surface method (RSM) was employed to evaluate the effect of Ti species coating parameters on the photocatalytic activity, which was found to be affected by the furnace temperature, N 2 flow rate and influx time of precursor gas. Application of RSM successfully increased the photocatalytic efficiency of the Ti-MgAl-LDH in methylene blue photodegradation under UV irradiation, leading to improved economy of the process. According to the results from X-ray diffraction, scanning electron microscopy, Brunner-Emmet-Teller and Barrett-Joyner-Hallender, thermogravimetric and differential thermal analysis, UV-vis diffuse reflectance spectra analyses, the Ti species (TiO 2 or/and Ti 4+ ) were successfully coated on the MgAl-LDH matrix. The Ti species on the surface of the Ti-MgAl-LDH lead to a higher photocatalytic performance than commercial TiO 2 -P25. The results suggested that CVD method provided a new approach for the industrial preparation of Ti-coating MgAl-LDH material with good photocatalytic performances. Copyright © 2017. Published by Elsevier B.V.

  9. Planar structured perovskite solar cells by hybrid physical chemical vapor deposition with optimized perovskite film thickness

    Science.gov (United States)

    Wei, Xiangyang; Peng, Yanke; Jing, Gaoshan; Cui, Tianhong

    2018-05-01

    The thickness of perovskite absorber layer is a critical parameter to determine a planar structured perovskite solar cell’s performance. By modifying the spin coating speed and PbI2/N,N-dimethylformamide (DMF) solution concentration, the thickness of perovskite absorber layer was optimized to obtain high-performance solar cells. Using a PbI2/DMF solution of 1.3 mol/L, maximum power conversion efficiency (PCE) of a perovskite solar cell is 15.5% with a perovskite film of 413 nm at 5000 rpm, and PCE of 14.3% was also obtained for a solar cell with a perovskite film of 182 nm thick. It is derived that higher concentration of PbI2/DMF will result in better perovskite solar cells. Additionally, these perovskite solar cells are highly uniform. In 14 sets of solar cells, standard deviations of 11 sets of solar cells were less than 0.50% and the smallest standard deviation was 0.25%, which demonstrates the reliability and effectiveness of hybrid physical chemical vapor deposition (HPCVD) method.

  10. Aspects of nitrogen surface chemistry relevant to TiN chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Schulberg, M.T.; Allendorf, M.D.; Outka, D.A.

    1996-08-01

    NH{sub 3} is an important component of many chemical vapor deposition (CVD) processes for TiN films, which are used for diffusion barriers and other applications in microelectronic circuits. In this study, the interaction of NH{sub 3} with TiN surfaces is examined with temperature programmed desorption (TPD) and Auger electron spectroscopy. NH{sub 3} has two adsorption states on TiN: a chemisorbed state and a multilayer state. A new method for analyzing TPD spectra in systems with slow pumping speeds yields activation energies for desorption for the two states of 24 kcal/mol and 7.3 kcal/mol, respectively. The sticking probability into the chemisorption state is {approximately}0.06. These results are discussed in the context of TiN CVD. In addition, the high temperature stability of TiN is investigated. TiN decomposes to its elements only after heating to 1300 K, showing that decomposition is unlikely to occur under CVD conditions.

  11. Thermal barrier coatings on gas turbine blades: Chemical vapor deposition (Review)

    Science.gov (United States)

    Igumenov, I. K.; Aksenov, A. N.

    2017-12-01

    Schemes are presented for experimental setups (reactors) developed at leading scientific centers connected with the development of technologies for the deposition of coatings using the CVD method: at the Technical University of Braunschweig (Germany), the French Aerospace Research Center, the Materials Research Institute (Tohoku University, Japan) and the National Laboratory Oak Ridge (USA). Conditions and modes for obtaining the coatings with high operational parameters are considered. It is established that the formed thermal barrier coatings do not fundamentally differ in their properties (columnar microstructure, thermocyclic resistance, thermal conductivity coefficient) from standard electron-beam condensates, but the highest growth rates and the perfection of the crystal structure are achieved in the case of plasma-chemical processes and in reactors with additional laser or induction heating of a workpiece. It is shown that CVD reactors can serve as a basis for the development of rational and more advanced technologies for coating gas turbine blades that are not inferior to standard electron-beam plants in terms of the quality of produced coatings and have a much simpler and cheaper structure. The possibility of developing a new technology based on CVD processes for the formation of thermal barrier coatings with high operational parameters is discussed, including a set of requirements for industrial reactors, high-performance sources of vapor precursors, and promising new materials.

  12. Initiated chemical vapor deposited nanoadhesive for bonding National Ignition Facility's targets

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Tom [Univ. of California, Berkeley, CA (United States)

    2016-05-19

    Currently, the target fabrication scientists in National Ignition Facility Directorate at Lawrence Livermore National Laboratory (LLNL) is studying the propagation force resulted from laser impulses impacting a target. To best study this, they would like the adhesive used to glue the target substrates to be as thin as possible. The main objective of this research project is to create adhesive glue bonds for NIF’s targets that are ≤ 1 μm thick. Polyglycidylmethacrylate (PGMA) thin films were coated on various substrates using initiated chemical vapor deposition (iCVD). Film quality studies using white light interferometry reveal that the iCVD PGMA films were smooth. The coated substrates were bonded at 150 °C under vacuum, with low inflow of Nitrogen. Success in bonding most of NIF’s mock targets at thicknesses ≤ 1 μm indicates that our process is feasible in bonding the real targets. Key parameters that are required for successful bonding were concluded from the bonding results. They include inert bonding atmosphere, sufficient contact between the PGMA films, and smooth substrates. Average bond strength of 0.60 MPa was obtained from mechanical shearing tests. The bonding failure mode of the sheared interfaces was observed to be cohesive. Future work on this project will include reattempt to bond silica aerogel to iCVD PGMA coated substrates, stabilize carbon nanotube forests with iCVD PGMA coating, and kinetics study of PGMA thermal crosslinking.

  13. Heteroepitaxial growth of wafer scale highly oriented graphene using inductively coupled plasma chemical vapor deposition

    International Nuclear Information System (INIS)

    Gao, Libo; Xu, Hai; Li, Linjun; Loh, Kian Ping; Yang, Yang; Fu, Qiang; Bao, Xinhe

    2016-01-01

    The chemical vapor deposition (CVD) of graphene on Cu has attracted much attention because of its industrial scalability. Herein, we report inductively coupled plasma-assisted CVD of epitaxially grown graphene on (111)-textured Cu film alloyed with a small amount of Ni, where large area high quality graphene film can be grown in less than 5 min at 800 °C, thus affording industrial scalability. The epitaxially grown graphene films on (111)-textured Cu contain grains which are predominantly aligned with the Cu lattice and about 10% of 30°-rotated grains (anti-grains). Such graphene films are exclusively monolayer and possess good electrical conductivity, high carrier mobility, and room temperature quantum Hall effect. Magnetoresistance measurements reveal that the reduction of the grain sizes from 150 nm to 50 nm produce increasing Anderson localization and the appearance of a transport gap. Owing to the presence of grain boundaries in these anti-grains, epitaxially grown graphene films possess n-type characteristics and exhibit ultra-high sensitivity to adsorbates. (letter)

  14. Chemical vapor deposition grown monolayer graphene field-effect transistors with reduced impurity concentration

    Science.gov (United States)

    Ha, Tae-Jun; Lee, Alvin

    2015-07-01

    We report on the restoration of the electronic characteristics of waferscale chemical vapor deposition (CVD) monolayer graphene field-effect transistors (GFETs) by reducing the impurity concentration. An optimized electropolishing process on copper foils combined with carbon-fluorine encapsulation using a suitable amorphous fluoropolymer enables reducing the surface roughness of graphene and screening out interfacial impurity scattering, which leads to an improvement in all key device metrics. The conductivity at the Dirac point is substantially reduced, resulting in an increase in the on-off current ratio. In addition, the field-effect mobility increased from 1817 to 3918 cm2/V-s, the impurity concentration decreased from 1.1 × 1012 to 2.1 × 1011 cm-2 and the electron and hole transport became more symmetric. Significantly, favorable shifts toward zero voltage were observed in the Dirac point. We postulate that the smoother surface due to electropolishing and a pool of strong dipole-dipole moments in the flouropolymer coating provide a charge buffer that relaxes the fluctuation in the electron-hole puddles. We also investigate the long-term stability in GFETs encapsulated with fluoropolymer, which exhibit a high hydrophobicity that suppresses the chemical interaction with water molecules. [Figure not available: see fulltext.

  15. Threefold atmospheric-pressure annealing for suppressing graphene nucleation on copper in chemical vapor deposition

    Science.gov (United States)

    Suzuki, Seiya; Nagamori, Takashi; Matsuoka, Yuki; Yoshimura, Masamichi

    2014-09-01

    Chemical vapor deposition (CVD) is a promising method of producing a large single-crystal graphene on a catalyst, especially on copper (Cu), and a further increase in domain size is desirable for electro/optic applications. Here, we report on threefold atmospheric-pressure (ATM) annealing for suppressing graphene nucleation in atmospheric CVD. Threefold ATM annealing formed a step and terrace surface of the underlying Cu, in contrast to ATM annealing. Atomic force microscopy and Auger electron mapping revealed that Si-containing particles existed on threefold-ATM- and ATM-annealed surfaces; particles on Cu had a lower density after threefold ATM annealing than after ATM annealing. The formation of a step and terrace surface and the lower density of particles following the threefold ATM annealing would play a role in reducing graphene nucleation. By combining threefold ATM annealing and electropolishing of Cu, the nucleation of graphene was effectively suppressed, and a submillimeter-sized hexagonal single-crystal graphene was successfully obtained.

  16. 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.

  17. Thermal stability of multilayer graphene films synthesized by chemical vapor deposition and stained by metallic impurities.

    Science.gov (United States)

    Kahng, Yung Ho; Lee, Sangchul; Park, Woojin; Jo, Gunho; Choe, Minhyeok; Lee, Jong-Hoon; Yu, Hyunung; Lee, Takhee; Lee, Kwanghee

    2012-02-24

    Thermal stability is an important property of graphene that requires thorough investigation. This study reports the thermal stability of graphene films synthesized by chemical vapor deposition (CVD) on catalytic nickel substrates in a reducing atmosphere. Electron microscopies, atomic force microscopy, and Raman spectroscopy, as well as electronic measurements, were used to determine that CVD-grown graphene films are stable up to 700 °C. At 800 °C, however, graphene films were etched by catalytic metal nanoparticles, and at 1000 °C many tortuous tubular structures were formed in the film and carbon nanotubes were formed at the film edges and at catalytic metal-contaminated sites. Furthermore, we applied our pristine and thermally treated graphene films as active channels in field-effect transistors and characterized their electrical properties. Our research shows that remnant catalytic metal impurities play a critical role in damaging graphene films at high temperatures in a reducing atmosphere: this damage should be considered in the quality control of large-area graphene films for high temperature applications.

  18. Synthesis and characterization of carbon nanofibers grown on Ni and Mo catalysts by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Eun Yi; Park, Heai Ku; Lee, Chang Seop [Keimyung University, Deagu (Korea, Republic of); Choi, Jong Ha [Dept. of Applied Chemistry, Andong National University, Andong (Korea, Republic of)

    2015-05-15

    In this study, we synthesized carbon nanofibers using Ni and Mo catalysts by chemical vapor deposition. Catalysts used in the synthesis of carbon nanofibers were prepared by changing the molar ratio of nickel nitrate and ammonium molybdate. Precipitates were then obtained by reacting with ammonium carbonate. The optimum temperature for synthesis of carbon nanofibers was found by changing it between 600 and 800 °C. At these temperatures, carbon nanofibers were synthesized with various ratios of catalysts. Structural and physiochemical properties were analyzed by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, Raman, and X-ray photoelectron spectroscopy. The specific surface area of synthesized carbon nanofibers was measured by BET. It was found that characterization of carbon nanofibers were significantly affected by the synthesis temperature and the concentration ratio of metal catalysts. When the catalyst with the concentration ratio of Ni and Mo was 6:4 at 800 °C, uniform carbon nanofibers with a diameter of 50 nm were grown. Crystallinity and amorphicity of the synthesized carbon nanofiber were excellent compared to those of carbon nanofibers synthesized with metal catalysts in different concentration ratios. A three-electrode cell was prepared by using the synthesized carbon nanofibers as anode of Li secondary battery. The electrochemical properties of carbon nanofibers were examined through cyclic voltammetry and galvanostatic charge–discharge.

  19. Magnetotransport study of granular chromium dioxide thin films prepared by the chemical vapor deposition technique

    International Nuclear Information System (INIS)

    Liang, J.-J.; Lee, S.F.; Yao, Y.D.; Wu, C.C.; Shyu, S.G.; Yu, C.

    2002-01-01

    The temperature-dependent magnetotransport properties of granular chromium dioxide (CrO 2 ) films with grain size about 1 μm grown by chemical vapor deposition on Si(0 0 1) substrates has been studied over a temperature range from 2 to 300 K. The magnetoresistance (MR) of about 20% at T=2 K decreases very fast with increasing temperature as a result of the rapid increase of the spin-independent hopping channel, whilst the temperature-dependent MR is almost the same for samples after 100 days annealing in air at room temperature, and its electrical resistivity at room temperature increases from roughly 50 to >75 μΩ m. The contribution to the conductance at T 1.33 . It becomes a poor metal at temperatures >160 K and its resistance follows R∼T 2 exp(-Δ/T). We have shown experimentally that the room temperature annealing results in the decomposition of CrO 2 into Cr 2 O 3 mainly near the surface of the films

  20. Layer-selective synthesis of bilayer graphene via chemical vapor deposition

    Science.gov (United States)

    Yang, Ning; Choi, Kyoungjun; Robertson, John; Park, Hyung Gyu

    2017-09-01

    A controlled synthesis of high-quality AB-stacked bilayer graphene by chemical vapor deposition demands a detailed understanding of the mechanism and kinetics. By decoupling the growth of the two layers via a growth-and-regrowth scheme, we report the kinetics and termination mechanisms of the bilayer graphene growth on copper. We observe, for the first time, that the secondary layer growth follows Gompertzian kinetics. Our observations affirm the postulate of a time-variant transition from a mass-transport-limited to a reaction-limited regimes and identify the mechanistic disparity between the monolayer growth and the secondary-layer expansion underneath the monolayer cover. It is the continuous carbon supply that drives the expansion of the graphene secondary layer, rather than the initially captured carbon amount, suggesting an essential role of the surface diffusion of reactant adsorbates in the interspace between the top graphene layer and the underneath copper surface. We anticipate that the layer selectivity of the growth relies on the entrance energetics of the adsorbed reactants to the graphene-copper interspace across the primary-layer edge, which could be engineered by tailoring the edge termination state. The temperature-reliant saturation area of the secondary-layer expansion is understood as a result of competitive attachment of carbon and hydrogen adatoms to the secondary-layer graphene edge.

  1. Transfer and patterning of chemical vapor deposited graphene by a multifunctional polymer film

    Science.gov (United States)

    Kaplas, Tommi; Bera, Arijit; Matikainen, Antti; Pääkkönen, Pertti; Lipsanen, Harri

    2018-02-01

    Graphene is seeking pathways towards applications, but there are still plenty of unresolved problems on the way. Many of those obstacles are related to synthesis and processing of graphene. Chemical vapor deposition (CVD) of graphene is currently one of the most promising techniques that enable scalable synthesis of high quality graphene on a copper substrate. From the transient metal substrate, the CVD graphene film is transferred to the desired dielectric substrate. Most often, the transfer process is done by using a supporting poly(methyl methacrylate) (PMMA) film, which is also a widely used electron beam resist. Conventionally, after graphene is transferred to the substrate, the supporting PMMA film is removed by organic solvents. Hence, the potential of using the same PMMA layer as a resist mask remains unexplored. Since PMMA is an electron beam resist, the same polymer film can be useful both for transferring and for patterning of graphene. In this work, we demonstrate simultaneous transfer and patterning of graphene by using the same PMMA film. With our demonstrated method, we are able to receive sub-micron resolution very easily. The graphene transfer and its subsequent patterning with the same resist layer may help developing device applications based on graphene and other 2D materials in the near future.

  2. Continuous, Highly Flexible, and Transparent Graphene Films by Chemical Vapor Deposition for Organic Photovoltaics

    KAUST Repository

    Gomez De Arco, Lewis

    2010-05-25

    We report the implementation of continuous, highly flexible, and transparent graphene films obtained by chemical vapor deposition (CVD) as transparent conductive electrodes (TCE) in organic photovoltaic cells. Graphene films were synthesized by CVD, transferred to transparent substrates, and evaluated in organic solar cell heterojunctions (TCE/poly-3,4- ethylenedioxythiophene:poly styrenesulfonate (PEDOT:PSS)/copper phthalocyanine/fullerene/bathocuproine/aluminum). Key to our success is the continuous nature of the CVD graphene films, which led to minimal surface roughness (∼ 0.9 nm) and offered sheet resistance down to 230 Ω/sq (at 72% transparency), much lower than stacked graphene flakes at similar transparency. In addition, solar cells with CVD graphene and indium tin oxide (ITO) electrodes were fabricated side-by-side on flexible polyethylene terephthalate (PET) substrates and were confirmed to offer comparable performance, with power conversion efficiencies (η) of 1.18 and 1.27%, respectively. Furthermore, CVD graphene solar cells demonstrated outstanding capability to operate under bending conditions up to 138°, whereas the ITO-based devices displayed cracks and irreversible failure under bending of 60°. Our work indicates the great potential of CVD graphene films for flexible photovoltaic applications. © 2010 American Chemical Society.

  3. Large-Area WS2 Film with Big Single Domains Grown by Chemical Vapor Deposition

    Science.gov (United States)

    Liu, Pengyu; Luo, Tao; Xing, Jie; Xu, Hong; Hao, Huiying; Liu, Hao; Dong, Jingjing

    2017-10-01

    High-quality WS2 film with the single domain size up to 400 μm was grown on Si/SiO2 wafer by atmospheric pressure chemical vapor deposition. The effects of some important fabrication parameters on the controlled growth of WS2 film have been investigated in detail, including the choice of precursors, tube pressure, growing temperature, holding time, the amount of sulfur powder, and gas flow rate. By optimizing the growth conditions at one atmospheric pressure, we obtained tungsten disulfide single domains with an average size over 100 μm. Raman spectra, atomic force microscopy, and transmission electron microscopy provided direct evidence that the WS2 film had an atomic layer thickness and a single-domain hexagonal structure with a high crystal quality. And the photoluminescence spectra indicated that the tungsten disulfide films showed an evident layer-number-dependent fluorescence efficiency, depending on their energy band structure. Our study provides an important experimental basis for large-area, controllable preparation of atom-thick tungsten disulfide thin film and can also expedite the development of scalable high-performance optoelectronic devices based on WS2 film.

  4. Surface functionalization of 3D-printed plastics via initiated chemical vapor deposition

    Directory of Open Access Journals (Sweden)

    Christine Cheng

    2017-08-01

    Full Text Available 3D printing is a useful fabrication technique because it offers design flexibility and rapid prototyping. The ability to functionalize the surfaces of 3D-printed objects allows the bulk properties, such as material strength or printability, to be chosen separately from surface properties, which is critical to expanding the breadth of 3D printing applications. In this work, we studied the ability of the initiated chemical vapor deposition (iCVD process to coat 3D-printed shapes composed of poly(lactic acid and acrylonitrile butadiene styrene. The thermally insulating properties of 3D-printed plastics pose a challenge to the iCVD process due to large thermal gradients along the structures during processing. In this study, processing parameters such as the substrate temperature and the filament temperature were systematically varied to understand how these parameters affect the uniformity of the coatings along the 3D-printed objects. The 3D-printed objects were coated with both hydrophobic and hydrophilic polymers. Contact angle goniometry and X-ray photoelectron spectroscopy were used to characterize the functionalized surfaces. Our results can enable the use of iCVD to functionalize 3D-printed materials for a range of applications such as tissue scaffolds and microfluidics.

  5. Defects in silicon carbide grown by fluorinated chemical vapor deposition chemistry

    Science.gov (United States)

    Stenberg, Pontus; Booker, Ian D.; Karhu, Robin; Pedersen, Henrik; Janzén, Erik; Ivanov, Ivan G.

    2018-04-01

    Point defects in n- and p-type 4H-SiC grown by fluorinated chemical vapor deposition (CVD) have been characterized optically by photoluminescence (PL) and electrically by deep-level transient spectroscopy (DLTS) and minority carrier transient spectroscopy (MCTS). The results are considered in comparison with defects observed in non-fluorinated CVD growth (e.g., using SiH4 instead of SiF4 as silicon precursor), in order to investigate whether specific fluorine-related defects form during the fluorinated CVD growth, which might prohibit the use of fluorinated chemistry for device-manufacturing purposes. Several new peaks identifying new defects appear in the PL of fluorinated-grown samples, which are not commonly observed neither in other halogenated chemistries, nor in the standard CVD chemistry using silane (SiH4). However, further investigation is needed in order to determine their origin and whether they are related to incorporation of F in the SiC lattice, or not. The electric characterization does not find any new electrically-active defects that can be related to F incorporation. Thus, we find no point defects prohibiting the use of fluorinated chemistry for device-making purposes.

  6. Ordered Ag nanocluster structures by vapor deposition on pre-patterned SiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Numazawa, Satoshi; Ranjan, Mukesh; Heinig, Karl-Heinz; Facsko, Stefan; Smith, Roger, E-mail: s.numazawa@hzdr.de [Helmholtz-Zentrum Dresden Rossendorf (HZDR), Institut fuer Ionenstrahlphysik und Materialforschung, PO Box 510119, 01314 Dresden (Germany)

    2011-06-08

    Highly ordered Ag nanocluster structures have been grown on pre-patterned amorphous SiO{sub 2} surfaces by oblique angle physical vapor deposition at room temperature. Despite the small undulation of the rippled surface, the stripe-like Ag nanoclusters are very pronounced, reproducible and well separated. Computer modeling of the growth has been performed with a lattice-based kinetic Monte Carlo (KMC) method using a combination of a simplified inter-atomic potential and experimental transition barriers taken from the literature. An effective transition event classification method is introduced which allows a boost factor of several thousand compared to a traditional KMC approach, thus allowing experimental time scales to be modeled. The simulation predicts a low sticking probability for the arriving atoms, millisecond order lifetimes for single Ag adatoms and {approx}1 nm square surface migration ranges of Ag adatoms. It is also shown that metal nucleations can trigger even on defect free surfaces. The simulations give excellent reproduction of the experimentally observed nanocluster growth patterns. (fast track communication)

  7. Ordered Ag nanocluster structures by vapor deposition on pre-patterned SiO2.

    Science.gov (United States)

    Numazawa, Satoshi; Ranjan, Mukesh; Heinig, Karl-Heinz; Facsko, Stefan; Smith, Roger

    2011-06-08

    Highly ordered Ag nanocluster structures have been grown on pre-patterned amorphous SiO(2) surfaces by oblique angle physical vapor deposition at room temperature. Despite the small undulation of the rippled surface, the stripe-like Ag nanoclusters are very pronounced, reproducible and well separated. Computer modeling of the growth has been performed with a lattice-based kinetic Monte Carlo (KMC) method using a combination of a simplified inter-atomic potential and experimental transition barriers taken from the literature. An effective transition event classification method is introduced which allows a boost factor of several thousand compared to a traditional KMC approach, thus allowing experimental time scales to be modeled. The simulation predicts a low sticking probability for the arriving atoms, millisecond order lifetimes for single Ag adatoms and ≈1 nm square surface migration ranges of Ag adatoms. It is also shown that metal nucleations can trigger even on defect free surfaces. The simulations give excellent reproduction of the experimentally observed nanocluster growth patterns.

  8. Continuous, highly flexible, and transparent graphene films by chemical vapor deposition for organic photovoltaics.

    Science.gov (United States)

    Gomez De Arco, Lewis; Zhang, Yi; Schlenker, Cody W; Ryu, Koungmin; Thompson, Mark E; Zhou, Chongwu

    2010-05-25

    We report the implementation of continuous, highly flexible, and transparent graphene films obtained by chemical vapor deposition (CVD) as transparent conductive electrodes (TCE) in organic photovoltaic cells. Graphene films were synthesized by CVD, transferred to transparent substrates, and evaluated in organic solar cell heterojunctions (TCE/poly-3,4-ethylenedioxythiophene:poly styrenesulfonate (PEDOT:PSS)/copper phthalocyanine/fullerene/bathocuproine/aluminum). Key to our success is the continuous nature of the CVD graphene films, which led to minimal surface roughness ( approximately 0.9 nm) and offered sheet resistance down to 230 Omega/sq (at 72% transparency), much lower than stacked graphene flakes at similar transparency. In addition, solar cells with CVD graphene and indium tin oxide (ITO) electrodes were fabricated side-by-side on flexible polyethylene terephthalate (PET) substrates and were confirmed to offer comparable performance, with power conversion efficiencies (eta) of 1.18 and 1.27%, respectively. Furthermore, CVD graphene solar cells demonstrated outstanding capability to operate under bending conditions up to 138 degrees , whereas the ITO-based devices displayed cracks and irreversible failure under bending of 60 degrees . Our work indicates the great potential of CVD graphene films for flexible photovoltaic applications.

  9. Dosimetric characterization of chemical-vapor-deposited diamond film irradiated with UV and beta radiation

    Science.gov (United States)

    Meléndrez, R.; Chernov, V.; Pedroza-Montero, M.; Barboza-Flores, M.

    2003-03-01

    Diamond is an excellent prospect for clinical radiation dosimetry due to its tissue-equivalence properties and being chemically inert. The use of diamond in radiation dosimetry has been halted by the high market price; although recently the capability of growing high quality polycrystalline has renewed the interest in using diamond films as detectors and dosimeters. In the present work we have characterized the dosimetric properties of diamond films synthesized by using chemical vapor deposition. The thermoluminescence (TL) of UV and beta exposed samples shows a glow curve composed of at least four peaks; one located around 587 K presents excellent TL properties suitable for dosimetric applications with ionizing and non ionizing radiation. The TL excitation spectrum exhibits maximum TL efficiency at 220 nm. The samples show regions of linear as well as supralinear behavior as a function or irradiation dose. The linear dose dependence was found for up to sixteen minutes of UV irradiation and 300 Gy for beta irradiated samples. The activation energy and the frequency factor were determined and found in the range of 0.32 - 0.89 eV and 1.1x10^2 - 2x10^8s_-1, respectively. The observed TL performance is reasonable appropriate to justify further investigation of diamond films as radiation dosimeters.

  10. High Yield Chemical Vapor Deposition Growth of High Quality Large-Area AB Stacked Bilayer Graphene

    Science.gov (United States)

    Liu, Lixin; Zhou, Hailong; Cheng, Rui; Yu, Woo Jong; Liu, Yuan; Chen, Yu; Shaw, Jonathan; Zhong, Xing; Huang, Yu; Duan, Xiangfeng

    2012-01-01

    Bernal stacked (AB stacked) bilayer graphene is of significant interest for functional electronic and photonic devices due to the feasibility to continuously tune its band gap with a vertical electrical field. Mechanical exfoliation can be used to produce AB stacked bilayer graphene flakes but typically with the sizes limited to a few micrometers. Chemical vapor deposition (CVD) has been recently explored for the synthesis of bilayer graphene but usually with limited coverage and a mixture of AB and randomly stacked structures. Herein we report a rational approach to produce large-area high quality AB stacked bilayer graphene. We show that the self-limiting effect of graphene growth on Cu foil can be broken by using a high H2/CH4 ratio in a low pressure CVD process to enable the continued growth of bilayer graphene. A high temperature and low pressure nucleation step is found to be critical for the formation of bilayer graphene nuclei with high AB stacking ratio. A rational design of a two-step CVD process is developed for the growth of bilayer graphene with high AB stacking ratio (up to 90 %) and high coverage (up to 99 %). The electrical transport studies demonstrated that devices made of the as-grown bilayer graphene exhibit typical characteristics of AB stacked bilayer graphene with the highest carrier mobility exceeding 4,000 cm2/V·s at room temperature, comparable to that of the exfoliated bilayer graphene. PMID:22906199

  11. Three dimensional graphene synthesis on nickel foam by chemical vapor deposition from ethylene

    International Nuclear Information System (INIS)

    Trinsoutrot, Pierre; Vergnes, Hugues; Caussat, Brigitte

    2014-01-01

    Highlights: • 3D multi-layers graphene networks were synthesized from ethylene on nickel foam. • The weight of graphene increased with run duration and when decreasing temperature. • Weight percentages of graphene as high as 15% were obtained. • A continuous mechanism of graphene formation probably exists in presence of ethylene. -- Abstract: 3D multi-layers graphene networks were synthesized on nickel foam from ethylene between 700 and 1000 °C by chemical vapor deposition. Large nickel foam substrates were used allowing the accurate measurement of graphene masses. The weight of graphene increased with run duration and when decreasing temperature. Graphene was also present inside the hollow branches of the foam. We demonstrated that the weights of graphene formed largely exceed the masses corresponding to carbon solubility into nickel. Indeed weight percentages of graphene as high as 15% were obtained, corresponding to graphene layers of 500 nm to 1 μm thick. This means that graphene formation could not be due only to carbon dissolution into nickel and then precipitation during the cooling step. Another mechanism probably co-exists, involving continuous graphene formation in presence of ethylene either by segregation from the dissolved carbon into nickel or by surface CVD growth

  12. Upcycling Waste Lard Oil into Vertical Graphene Sheets by Inductively Coupled Plasma Assisted Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    Angjian Wu

    2017-10-01

    Full Text Available Vertical graphene (VG sheets were single-step synthesized via inductively coupled plasma (ICP-enhanced chemical vapor deposition (PECVD using waste lard oil as a sustainable and economical carbon source. Interweaved few-layer VG sheets, H2, and other hydrocarbon gases were obtained after the decomposition of waste lard oil. The influence of parameters such as temperature, gas proportion, ICP power was investigated to tune the nanostructures of obtained VG, which indicated that a proper temperature and H2 concentration was indispensable for the synthesis of VG sheets. Rich defects of VG were formed with a high I D / I G ratio (1.29, consistent with the dense edges structure observed in electron microscopy. Additionally, the morphologies, crystalline degree, and wettability of nanostructure carbon induced by PECVD and ICP separately were comparatively analyzed. The present work demonstrated the potential of our PECVD recipe to synthesize VG from abundant natural waste oil, which paved the way to upgrade the low-value hydrocarbons into advanced carbon material.

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

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Situ; Kamakura, Ryosuke; Murai, Shunsuke; Fujita, Koji; Tanaka, Katsuhisa, E-mail: tanaka@dipole7.kuic.kyoto-u.ac.jp

    2017-01-15

    We have synthesized polycrystalline thin film composed of a single phase of metastable bismuth iron garnet, Bi{sub 3}Fe{sub 5}O{sub 12}, 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. - Highlights: • Thin film of polycrystalline Bi{sub 3}Fe{sub 5}O{sub 12} was prepared by the mist CVD method. • Optimized conditions were found for the synthesis of single phase of Bi{sub 3}Fe{sub 5}O{sub 12}. • The Faraday rotation angle at 633 nm is –5.2 deg/μm at room temperature. • The Faraday rotation is interpreted by the electronic transitions of Fe{sup 3+} ions.

  14. Equilibrium chemical vapor deposition growth of Bernal-stacked bilayer graphene.

    Science.gov (United States)

    Zhao, Pei; Kim, Sungjin; Chen, Xiao; Einarsson, Erik; Wang, Miao; Song, Yenan; Wang, Hongtao; Chiashi, Shohei; Xiang, Rong; Maruyama, Shigeo

    2014-11-25

    Using ethanol as the carbon source, self-limiting growth of AB-stacked bilayer graphene (BLG) has been achieved on Cu via an equilibrium chemical vapor deposition (CVD) process. We found that during this alcohol catalytic CVD (ACCVD) a source-gas pressure range exists to break the self-limitation of monolayer graphene on Cu, and at a certain equilibrium state it prefers to form uniform BLG with a high surface coverage of ∼94% and AB-stacking ratio of nearly 100%. More importantly, once the BLG is completed, this growth shows a self-limiting manner, and an extended ethanol flow time does not result in additional layers. We investigate the mechanism of this equilibrium BLG growth using isotopically labeled (13)C-ethanol and selective surface aryl functionalization, and results reveal that during the equilibrium ACCVD process a continuous substitution of graphene flakes occurs to the as-formed graphene and the BLG growth follows a layer-by-layer epitaxy mechanism. These phenomena are significantly in contrast to those observed for previously reported BLG growth using methane as precursor.

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

    KAUST Repository

    Hussain, Aftab M.

    2013-04-01

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

  16. SiO{sub 2} coating of silver nanoparticles by photoinduced chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Boies, Adam M; Girshick, Steven L [Department of Mechanical Engineering, University of Minnesota, 111 Church Street SE, Minneapolis, MN 55455 (United States); Roberts, Jeffrey T [Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, MN 55455 (United States); Zhang Bin; Nakamura, Toshitaka; Mochizuki, Amane, E-mail: jtrob@umn.ed, E-mail: slg@umn.ed [Nitto Denko Technical Corporation, 501 Via Del Monte, Oceanside, CA 92058 (United States)

    2009-07-22

    Gas-phase silver nanoparticles were coated with silicon dioxide (SiO{sub 2}) by photoinduced chemical vapor deposition (photo-CVD). Silver nanoparticles, produced by inert gas condensation, and a SiO{sub 2} precursor, tetraethylorthosilicate (TEOS), were exposed to vacuum ultraviolet (VUV) radiation at atmospheric pressure and varying temperatures. The VUV photons dissociate the TEOS precursor, initiating a chemical reaction that forms SiO{sub 2} coatings on the particle surfaces. Coating thicknesses were measured for a variety of operation parameters using tandem differential mobility analysis and transmission electron microscopy. The chemical composition of the particle coatings was analyzed using energy dispersive x-ray spectrometry and Fourier transform infrared spectroscopy. The highest purity films were produced at 300-400 {sup 0}C with low flow rates of additional oxygen. The photo-CVD coating technique was shown to effectively coat nanoparticles and limit core particle agglomeration at concentrations up to 10{sup 7} particles cm{sup -3}.

  17. Etching characteristics and application of physical-vapor-deposited amorphous carbon for multilevel resist

    International Nuclear Information System (INIS)

    Kim, H. T.; Kwon, B. S.; Lee, N.-E.; Park, Y. S.; Cho, H. J.; Hong, B.

    2008-01-01

    For the fabrication of a multilevel resist (MLR) based on a very thin, physical-vapor-deposited (PVD) amorphous carbon (a-C) layer, the etching characteristics of the PVD a-C layer with a SiO x hard mask were investigated in a dual-frequency superimposed capacitively coupled plasma etcher by varying the following process parameters in O 2 /N 2 /Ar plasmas: high-frequency/low-frequency combination (f HF /f LF ), HF/LF power ratio (P HF /P LF ), and O 2 and N 2 flow rates. The very thin nature of the a-C layer helps to keep the aspect ratio of the etched features low. The etch rate of the PVD a-C layer increased with decreasing f HF /f LF combination and increasing P LF and was initially increased but then decreased with increasing N 2 flow rate in O 2 /N 2 /Ar plasmas. The application of a 30 nm PVD a-C layer in the MLR structure of ArF PR/BARC/SiO x /PVD a-C/TEOS oxide supported the possibility of using a very thin PVD a-C layer as an etch-mask layer for the TEOS-oxide layer

  18. Morphology and photoresponse of crystalline antimony film grown on mica by physical vapor deposition

    Directory of Open Access Journals (Sweden)

    Shafa Muhammad

    2016-09-01

    Full Text Available Antimony is a promising material for the fabrication of photodetectors. This study deals with the growth of a photosensitive thin film by the physical vapor deposition (PVD of antimony onto mica surface in a furnace tube. The geometry of the grown structures was studied via scanning electron microscopy (SEM, X-ray diffraction (XRD, energy-dispersive X-ray spectroscopy (EDX and elemental diffraction analysis. XRD peaks of the antimony film grown on mica mostly matched with JCPDF Card. The formation of rhombohedral crystal structures in the film was further confirmed by SEM micrographs and chemical composition analysis. The Hall measurements revealed good electrical conductivity of the film with bulk carrier concentration of the order of 1022 Ω·cm-3 and mobility of 9.034 cm2/Vs. The grown film was successfully tested for radiation detection. The photoresponse of the film was evaluated using its current-voltage characteristics. These investigations revealed that the photosensitivity of the antimony film was 20 times higher than that of crystalline germanium.

  19. Direct growth of graphene on gallium nitride by using chemical vapor deposition without extra catalyst

    International Nuclear Information System (INIS)

    Zhao Yun; An Tie-Lei; Yang Jian-Kun; Wei Tong-Bo; Duan Rui-Fei; Wang Gang; Yang Huai-Chao; Chen Min-Jiang; Yu Fang; Tao Li; Sun Lian-Feng

    2014-01-01

    Graphene on gallium nitride (GaN) will be quite useful when the graphene is used as transparent electrodes to improve the performance of gallium nitride devices. In this work, we report the direct synthesis of graphene on GaN without an extra catalyst by chemical vapor deposition. Raman spectra indicate that the graphene films are uniform and about 5–6 layers in thickness. Meanwhile, the effects of growth temperatures on the growth of graphene films are systematically studied, of which 950 °C is found to be the optimum growth temperature. The sheet resistance of the grown graphene is 41.1 Ω/square, which is close to the lowest sheet resistance of transferred graphene reported. The mechanism of graphene growth on GaN is proposed and discussed in detail. XRD spectra and photoluminescence spectra indicate that the quality of GaN epi-layers will not be affected after the growth of graphene. (condensed matter: structural, mechanical, and thermal properties)

  20. Synthesis of high performance ceramic fibers by chemical vapor deposition for advanced metallics reinforcing

    Science.gov (United States)

    Revankar, Vithal; Hlavacek, Vladimir

    1991-01-01

    The chemical vapor deposition (CVD) synthesis of fibers capable of effectively reinforcing intermetallic matrices at elevated temperatures which can be used for potential applications in high temperature composite materials is described. This process was used due to its advantage over other fiber synthesis processes. It is extremely important to produce these fibers with good reproducible and controlled growth rates. However, the complex interplay of mass and energy transfer, blended with the fluid dynamics makes this a formidable task. The design and development of CVD reactor assembly and system to synthesize TiB2, CrB, B4C, and TiC fibers was performed. Residual thermal analysis for estimating stresses arising form thermal expansion mismatch were determined. Various techniques to improve the mechanical properties were also performed. Various techniques for improving the fiber properties were elaborated. The crystal structure and its orientation for TiB2 fiber is discussed. An overall view of the CVD process to develop CrB2, TiB2, and other high performance ceramic fibers is presented.

  1. Effect of e-beam irradiation on graphene layer grown by chemical vapor deposition

    International Nuclear Information System (INIS)

    Iqbal, M. Z.; Kumar Singh, Arun; Iqbal, M. W.; Seo, Sunae; Eom, Jonghwa

    2012-01-01

    We have grown graphene by chemical vapor deposition (CVD) and transferred it onto Si/SiO 2 substrates to make tens of micron scale devices for Raman spectroscopy study. The effect of electron beam (e-beam) irradiation of various doses (600 to 12 000 μC/cm 2 ) on CVD grown graphene has been examined by using Raman spectroscopy. It is found that the radiation exposures result in the appearance of the strong disorder D band attributed the damage to the lattice. The evolution of peak frequencies, intensities, and widths of the main Raman bands of CVD graphene is analyzed as a function of defect created by e-beam irradiation. Especially, the D and G peak evolution with increasing radiation dose follows the amorphization trajectory, which suggests transformation of graphene to the nanocrystalline and then to amorphous form. We have also estimated the strain induced by e-beam irradiation in CVD graphene. These results obtained for CVD graphene are in line with previous findings reported for the mechanically exfoliated graphene [D. Teweldebrhan and A. A. Balandin, Appl. Phys. Lett. 94, 013101 (2009)]. The results have important implications for CVD graphene characterization and device fabrication, which rely on the electron microscopy.

  2. Superhydrophobic multi-scale ZnO nanostructures fabricated by chemical vapor deposition method.

    Science.gov (United States)

    Zhou, Ming; Feng, Chengheng; Wu, Chunxia; Ma, Weiwei; Cai, Lan

    2009-07-01

    The ZnO nanostructures were synthesized on Si(100) substrates by chemical vapor deposition (CVD) method. Different Morphologies of ZnO nanostructures, such as nanoparticle film, micro-pillar and micro-nano multi-structure, were obtained with different conditions. The results of XRD and TEM showed the good quality of ZnO crystal growth. Selected area electron diffraction analysis indicates the individual nano-wire is single crystal. The wettability of ZnO was studied by contact angle admeasuring apparatus. We found that the wettability can be changed from hydrophobic to super-hydrophobic when the structure changed from smooth particle film to single micro-pillar, nano-wire and micro-nano multi-scale structure. Compared with the particle film with contact angle (CA) of 90.7 degrees, the CA of single scale microstructure and sparse micro-nano multi-scale structure is 130-140 degrees, 140-150 degrees respectively. But when the surface is dense micro-nano multi-scale structure such as nano-lawn, the CA can reach to 168.2 degrees . The results indicate that microstructure of surface is very important to the surface wettability. The wettability on the micro-nano multi-structure is better than single-scale structure, and that of dense micro-nano multi-structure is better than sparse multi-structure.

  3. Effect of temperature on growth and structure of carbon nanotubes by chemical vapor deposition

    Science.gov (United States)

    Li, W. Z.; Wen, J. G.; Ren, Z. F.

    The effect of temperature on growth and structure of carbon nanotubes (NTs) using chemical vapor deposition (CVD) has been investigated. Iron embedded silica was used to grow NTs in large quantity at various temperatures from 600 to 1050 °C with gas pressure fixed at 0.6 and 760 Torr, respectively. The growth and structure of the NTs are strongly affected by the temperature. At low gas pressure, the NTs are completely hollow at low temperature and bamboo-like structure at high temperature. While at high gas pressure, all the NTs are bamboo-like structure regardless of temperature. The diameter of NTs increases significantly with temperature. At low gas pressure the diameter gets bigger by mainly increasing the number of graphene layers of the wall of NTs, whereas at high gas pressure the diameter gets bigger by increasing both the number of graphene layers of the wall and the inner diameter of the NTs. This result indicates that the growth temperature is crucial in synthesizing NTs with different structures. The findings here are important for realizing controlled growth of NTs for their applications in different fields.

  4. H2-dependent attachment kinetics and shape evolution in chemical vapor deposition graphene growth

    Science.gov (United States)

    Meca, Esteban; Shenoy, Vivek B.; Lowengrub, John

    2017-09-01

    Experiments on graphene growth through chemical vapor deposition (CVD) involving methane (CH4) and hydrogen (H2) gases reveal a complex shape evolution and a non-monotonic dependence on the partial pressure of H2 ({{p}{{\\text{H}2}}} ). To explain these intriguing observations, we develop a microkinetic model for the stepwise decomposition of CH4 into mobile radicals and consider two possible mechanisms of attachment to graphene crystals: CH radicals to hydrogen-decorated edges of the crystals and C radicals to bare crystal edges. We derive an effective mass flux and an effective kinetic coefficient, both of which depend on {{p}{{\\text{H}2}}} , and incorporate these into a phase field model. The model reproduces both the non-monotonic dependence on {{p}{{\\text{H}2}}} and the characteristic shapes of graphene crystals observed in experiments. At small {{p}{{\\text{H}2}}} , growth is limited by the kinetics of attachment while at large {{p}{{\\text{H}2}}} growth is limited because the effective mass flux is small. We also derive a simple analytical model that captures the non-monotone behavior, enables the two mechanisms of attachment to be distinguished and provides guidelines for CVD growth of defect-free 2D crystals.

  5. Substrate-orientation dependent epitaxial growth of highly ordered diamond nanosheet arrays by chemical vapor deposition.

    Science.gov (United States)

    Wang, Shuguang; Ji, Xixi; Ao, Yu; Yu, Jie

    2018-02-08

    Three-dimensional ordering of two-dimensional nanomaterials has long been a challenge. Simultaneously, diamond nanomaterials are difficult to synthesize due to the harsh synthesizing conditions required. Here, we report substrate-crystal-orientation dependent growth of diamond nanosheets (DNSs) by chemical vapor deposition, which generates different DNS arrays on different substrates. The DNSs are grown by the in-plane epitaxy of the diamond {111} planes. So the arrays are highly ordered and solely determined by the spatial orientation of the {111} planes in the diamond FCC structure. The DNSs grown on the {110}, {111}, {001}, and {113} oriented substrates show inclination angles ranging from 90 to 29.5°. The DNSs with larger inclination angles grow preferentially, forming parallelogram arrays with inclination angles of 90° on the {110} substrates and parallel-line arrays with inclination angles of 80° on the {113} substrates. The density, thickness, size, and morphology of the DNSs have been well controlled. The present understanding and materials are highly promising for many applications such as sensors, catalysis, photonics, thermal management, and electronics.

  6. Desalination by Membrane Distillation using Electrospun Polyamide Fiber Membranes with Surface Fluorination by Chemical Vapor Deposition.

    Science.gov (United States)

    Guo, Fei; Servi, Amelia; Liu, Andong; Gleason, Karen K; Rutledge, Gregory C

    2015-04-22

    Fibrous membranes of poly(trimethyl hexamethylene terephthalamide) (PA6(3)T) were fabricated by electrospinning and rendered hydrophobic by applying a conformal coating of poly(1H,1H,2H,2H-perfluorodecyl acrylate) (PPFDA) using initiated chemical vapor deposition (iCVD). A set of iCVD-treated electrospun PA6(3)T fiber membranes with fiber diameters ranging from 0.25 to 1.8 μm were tested for desalination using the air gap membrane distillation configuration. Permeate fluxes of 2-11 kg/m2/h were observed for temperature differentials of 20-45 °C between the feed stream and condenser plate, with rejections in excess of 99.98%. The liquid entry pressure was observed to increase dramatically, from 15 to 373 kPa with reduction in fiber diameter. Contrary to expectation, for a given feed temperature the permeate flux was observed to increase for membranes of decreasing fiber diameter. The results for permeate flux and salt rejection show that it is possible to construct membranes for membrane distillation even from intrinsically hydrophilic materials after surface modification by iCVD and that the fiber diameter is shown to play an important role on the membrane distillation performance in terms of permeate flux, salt rejection, and liquid entry pressure.

  7. The density factor in the synthesis of carbon nanotube forest by injection chemical vapor deposition

    Science.gov (United States)

    Call, R. W.; Read, C. G.; Mart, C.; Shen, T.-C.

    2012-12-01

    Beneath the seeming straight-forwardness of growing carbon nanotube (CNT) forests by the injection chemical vapor deposition (CVD) method, control of the forest morphology on various substrates is yet to be achieved. Using ferrocene dissolved in xylene as the precursor, we demonstrate that the concentration of ferrocene and the injection rate of the precursor dictate the CNT density of these forests. However, CNT density will also be affected by the substrates and the growth temperature which determine the diffusion of the catalyst adatoms. The CNT growth rate is controlled by the temperature and chemical composition of the gases in the CVD reactor. We show that the final height of the forest is diffusion limited, at least in the conditions of our experiments. Because of the proximity and entanglement of the CNTs in a forest, the growing CNTs can lift-up the inactive CNTs resulting in reduced density toward the base of the forest unless the nucleation rate of the new catalyst particles is sufficiently high to replenish the inactive catalyst particles. Significant loss of CNT attachment by the lift-up effect reduces the adhesion of the forest to the substrate. Optimizing the ferrocene concentration in the precursor, precursor injection rate, gas mixture, substrate, and temperature is necessary to achieve desired forest morphology for specific applications.

  8. Synthesis of molybdenum carbide superconducting compounds by microwave-plasma chemical vapor deposition

    Science.gov (United States)

    Zhao, Hongyang; Cai, Kang; Ma, Zhibin; Cheng, Zhenxiang; Jia, Tingting; Kimura, Hideo; Fu, Qiuming; Tao, Hong; Xiong, Liwei

    2018-02-01

    A method to synthesize molybdenum carbides has been developed based on microwave plasma treatment with methane and hydrogen mixed gases, using a microwave-plasma chemical vapor deposition device. The device framework and its mechanism are described in detail. Two-dimensional α-Mo2C has been directly synthesized by a plate-to-plate substrate holder structure with a microwave power of 920 W and a partial pressure of 20 kPa. In-situ optical emission spectroscopy was used to measure the radical types in the plasma ball during glow discharge. The as-grown α-Mo2C samples were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy to determine their phases, purity and chemical groups. The superconducting transition temperature was measured, and the transition temperatures of the relevant phases are discussed in detail. The results confirmed that this method is an efficient way to obtain molybdenum carbides and inspire new research interest in transition metal carbides, which have many intrinsic local properties and applications.

  9. Monolayer MoSe 2 Grown by Chemical Vapor Deposition for Fast Photodetection

    KAUST Repository

    Chang, Yung-Huang

    2014-08-26

    Monolayer molybdenum disulfide (MoS2) has become a promising building block in optoelectronics for its high photosensitivity. However, sulfur vacancies and other defects significantly affect the electrical and optoelectronic properties of monolayer MoS2 devices. Here, highly crystalline molybdenum diselenide (MoSe2) monolayers have been successfully synthesized by the chemical vapor deposition (CVD) method. Low-temperature photoluminescence comparison for MoS2 and MoSe 2 monolayers reveals that the MoSe2 monolayer shows a much weaker bound exciton peak; hence, the phototransistor based on MoSe2 presents a much faster response time (<25 ms) than the corresponding 30 s for the CVD MoS2 monolayer at room temperature in ambient conditions. The images obtained from transmission electron microscopy indicate that the MoSe exhibits fewer defects than MoS2. This work provides the fundamental understanding for the differences in optoelectronic behaviors between MoSe2 and MoS2 and is useful for guiding future designs in 2D material-based optoelectronic devices. © 2014 American Chemical Society.

  10. Composition and Morphology Control of Metal Dichalcogenides via Chemical Vapor Deposition for Photovoltaic and Nanoelectronic Applications

    Science.gov (United States)

    Samad, Leith L. J.

    The body of work reviewed here encompasses a variety of metal dichalcogenides all synthesized using chemical vapor deposition (CVD) for solar and electronics applications. The first reported phase-pure CVD synthesis of iron pyrite thin films is presented with detailed structural and electrochemical analysis. The phase-pure thin film and improved crystal growth on a metallic backing material represents one of the best options for potential solar applications using iron pyrite. Large tin-sulfur-selenide solid solution plates with tunable bandgaps were also synthesized via CVD as single-crystals with a thin film geometry. Solid solution tin-sulfur-selenide plates were demonstrated to be a new material for solar cells with the first observed solar conversion efficiencies up to 3.1%. Finally, a low temperature molybdenum disulfide vertical heterostructure CVD synthesis with layered controlled growth was achieved with preferential growth enabled by Van der Waals epitaxy. Through recognition of additional reaction parameters, a fully regulated CVD synthesis enabled the controlled growth of 1-6 molybdenum disulfide monolayers for nanoelectronic applications. The improvements in synthesis and materials presented here were all enabled by the control afforded by CVD such that advances in phase purity, growth, and composition control of several metal dichalcogenides were achieved. Further work will be able to take full advantage of these advances for future solar and electronics technologies.

  11. Surface functionalization of 3D-printed plastics via initiated chemical vapor deposition.

    Science.gov (United States)

    Cheng, Christine; Gupta, Malancha

    2017-01-01

    3D printing is a useful fabrication technique because it offers design flexibility and rapid prototyping. The ability to functionalize the surfaces of 3D-printed objects allows the bulk properties, such as material strength or printability, to be chosen separately from surface properties, which is critical to expanding the breadth of 3D printing applications. In this work, we studied the ability of the initiated chemical vapor deposition (iCVD) process to coat 3D-printed shapes composed of poly(lactic acid) and acrylonitrile butadiene styrene. The thermally insulating properties of 3D-printed plastics pose a challenge to the iCVD process due to large thermal gradients along the structures during processing. In this study, processing parameters such as the substrate temperature and the filament temperature were systematically varied to understand how these parameters affect the uniformity of the coatings along the 3D-printed objects. The 3D-printed objects were coated with both hydrophobic and hydrophilic polymers. Contact angle goniometry and X-ray photoelectron spectroscopy were used to characterize the functionalized surfaces. Our results can enable the use of iCVD to functionalize 3D-printed materials for a range of applications such as tissue scaffolds and microfluidics.

  12. Vapor phase reactions in polymerization plasma for divinylsiloxane-bis-benzocyclobutene film deposition

    International Nuclear Information System (INIS)

    Kinoshita, Keizo; Nakano, Akinori; Kawahara, Jun; Kunimi, Nobutaka; Hayashi, Yoshihiro; Kiso, Osamu; Saito, Naoaki; Nakamura, Keiji; Kikkawa, Takamaro

    2006-01-01

    Vapor phase reactions in plasma polymerization of divinylsiloxane-bis-benzocyclobutene (DVS-BCB) low-k film depositions on 300 mm wafers were studied using mass spectrometry, in situ Fourier transform infrared, and a surface wave probe. Polymerization via Diels-Alder cycloaddition reaction was identified by the detection of the benzocyclohexene group. Hydrogen addition and methyl group desorption were also detected in DVS-BCB monomer and related large molecules. The dielectric constant k of plasma polymerized DVS-BCB with a plasma source power range up to 250 W was close to ∼2.7 of thermally polymerized DVS-BCB, and increased gradually over 250 W. The electron density at 250 W was about 1.5x10 10 cm -3 . The increase of the k value at higher power was explained by the decrease of both large molecular species via multistep dissociation and incorporation of silica components into the polymer. It was found that the reduction of electron density as well as precursor residence time is important for the plasma polymerization process to prevent the excess dissociation of the precursor

  13. The evolution of carbon nanotubes during their growth by plasma enhanced chemical vapor deposition

    International Nuclear Information System (INIS)

    Wang Hengzhi; Ren, Z F

    2011-01-01

    During the growth of carbon nanotubes (CNTs) by plasma enhanced chemical vapor deposition (PECVD), plasma etching is the crucial factor that determines the growth mode and alignment of the CNTs. Focusing on a thin catalyst coating (Ni = 5 nm), this study finds that the CNT growth by PECVD goes through three stages from randomly entangled (I-CNTs) to partially aligned (II-CNTs) to fully aligned (III-CNTs). The I-CNTs and II-CNTs are mostly etched away by the plasma as time goes by ending up with III-CNTs as the only product when growth time is long enough. However, with a thickness of the catalyst coating of 10 nm or more, neither I-CNTs nor II-CNTs are produced, but III-CNTs are the only type of CNTs grown during the whole growth process. During the growth of III-CNTs, the catalyst particles (Ni) stay on the tips of each of the aligned CNTs and act as a 'safety helmet' to protect the CNTs from plasma ion bombardment. On the other hand, it is also the plasma that limits the growth of III-CNTs, since the plasma eventually etches all the catalytic particles out and stops the growth.

  14. A directly patternable click-active polymer film via initiated chemical vapor deposition (iCVD)

    International Nuclear Information System (INIS)

    Im, Sung Gap; Kim, Byeong-Su; Tenhaeff, Wyatt E.; Hammond, Paula T.; Gleason, Karen K.

    2009-01-01

    A new 'click chemistry' active functional polymer film was directly obtained from a commercially available monomer of propargyl acrylate (PA) via easy, one-step process of initiated chemical vapor deposition (iCVD). Fourier transform infrared (FTIR) spectra confirmed that significant amount of the click-active acetylene functional group was retained after the iCVD process. The degree of crosslinking could be controlled by intentionally adding crosslinker, such as ethylene glycol diacrylate (EGDA) that was polymerized with PA to form click-active, completely insoluble copolymer. The formed iCVD polymers could also be grafted on various inorganic substrates with silane coupling agents. These crosslinking and grafting techniques give iCVD polymers chemical and mechanical stability, which allows iCVD polymers applicable to various click chemistry without any modification of reaction conditions. Pre-patterned iCVD polymer could be obtained via photolithography and an azido-functionalized dye molecule was also successfully attached on iCVD polymer via click chemistry. Moreover, pPA film demonstrated sensitivity to e-beam irradiation, which enabled clickable substrates having nanometer scale patterns without requiring the use of an additional e-beam resist. Direct e-beam exposure of this multifunctional iCVD layer, a 200 nm pattern, and QD particles were selectively conjugated on the substrates via click chemistry. Thus, iCVD pPA has shown dual functionality as of 'clickable' e-beam sensitive material.

  15. Uniformly Distributed Graphene Domain Grows on Standing Copper via Low-Pressure Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    Shih-Hao Chan

    2013-01-01

    Full Text Available Uniformly distributed graphene domains were synthesized on standing copper foil by a low-pressure chemical vapor deposition system. This method improved the distribution of the graphene domains at different positions on the same piece of copper foil along the forward direction of the gas flow. Scanning electron microscopy (SEM showed the average size of the graphene domains to be about ~20 m. This results show that the sheet resistance of monolayer graphene on a polyethylene terephthalate (PET substrate is about ~359 /□ whereas that of the four-layer graphene films is about ~178 /□, with a transmittance value of 88.86% at the 550 nm wavelength. Furthermore, the sheet resistance can be reduced with the addition of HNO3 resulting in a value of 84 /□. These values meet the absolute standard for touch sensor applications, so we believe that this method can be a candidate for some transparent conductive electrode applications.

  16. Initiated chemical vapor deposition of pH responsive poly(2-diisopropylamino)ethyl methacrylate thin films

    International Nuclear Information System (INIS)

    Karaman, Mustafa; Çabuk, Nihat

    2012-01-01

    Poly(2-(diisopropylamino)ethyl methacrylate) (PDPAEMA) thin films were deposited on low temperature substrates by initiated chemical vapor deposition (iCVD) method using tertbutyl peroxide as an initiator. Very high deposition rates up to 38 nm/min were observed at low filament temperatures due to the use of the initiator. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy show the formation of PDPAEMA films with high retention of tertiary amine functionality which is responsible for pH induced changes in the wetting behavior of the surfaces. As-deposited PDPAEMA thin films on flat Si surface showed a reversible switching of water contact angle values between 87° and 28°; after successive treatments of high and low pH water solutions, respectively. Conformal and non-damaging nature of iCVD allowed to functionalize fragile and rough electrospun poly(methyl methacrylate) fiber mat surfaces by PDPAEMA, which creates a surface with a switching behavior between superhydrophobic and approaching superhydrophilic with contact angle values of 155 ± 3°and 22 ± 5°, respectively. - Highlights: ► Poly(2-diisopropylaminoethyl methacrylate) thin films were deposited by a dry process. ► Initiated chemical vapor deposition can produce thin films on fragile substrates. ► We report a reversible pH-induced transition from hydrophilic to super-hydrophobic.

  17. On-line coating of glass with tin oxide by atmospheric pressure chemical vapor deposition.

    Energy Technology Data Exchange (ETDEWEB)

    Allendorf, Mark D.; Sopko, J.F. (PPF Industries, Pittsburgh, PA); Houf, William G.; Chae, Yong Kee; McDaniel, Anthony H.; Li, M. (PPF Industries, Pittsburgh, PA); McCamy, J.W. (PPF Industries, Pittsburgh, PA)

    2006-11-01

    Atmospheric pressure chemical vapor deposition (APCVD) of tin oxide is a very important manufacturing technique used in the production of low-emissivity glass. It is also the primary method used to provide wear-resistant coatings on glass containers. The complexity of these systems, which involve chemical reactions in both the gas phase and on the deposition surface, as well as complex fluid dynamics, makes process optimization and design of new coating reactors a very difficult task. In 2001 the U.S. Dept. of Energy Industrial Technologies Program Glass Industry of the Future Team funded a project to address the need for more accurate data concerning the tin oxide APCVD process. This report presents a case study of on-line APCVD using organometallic precursors, which are the primary reactants used in industrial coating processes. Research staff at Sandia National Laboratories in Livermore, CA, and the PPG Industries Glass Technology Center in Pittsburgh, PA collaborated to produce this work. In this report, we describe a detailed investigation of the factors controlling the growth of tin oxide films. The report begins with a discussion of the basic elements of the deposition chemistry, including gas-phase thermochemistry of tin species and mechanisms of chemical reactions involved in the decomposition of tin precursors. These results provide the basis for experimental investigations in which tin oxide growth rates were measured as a function of all major process variables. The experiments focused on growth from monobutyltintrichloride (MBTC) since this is one of the two primary precursors used industrially. There are almost no reliable growth-rate data available for this precursor. Robust models describing the growth rate as a function of these variables are derived from modeling of these data. Finally, the results are used to conduct computational fluid dynamic simulations of both pilot- and full-scale coating reactors. As a result, general conclusions are

  18. Properties and electric characterizations of tetraethyl orthosilicate-based plasma enhanced chemical vapor deposition oxide film deposited at 400 °C for through silicon via application

    International Nuclear Information System (INIS)

    Su, Meiying; Yu, Daquan; Liu, Yijun; Wan, Lixi; Song, Chongshen; Dai, Fengwei; Xue, Kai; Jing, Xiangmeng; Guidotti, Daniel

    2014-01-01

    The dielectric via liner of through silicon vias was deposited at 400 °C using a tetraethyl orthosilicate (TEOS)-based plasma enhanced chemical vapor deposition process in a via-middle integration scheme. The morphology, conformality and chemical compositions of the liner film were characterized using field emission scanning electron microscopy and Fourier Transform Infrared spectroscopy. The thermal properties and electrical performance of blanket TEOS films were investigated by high temperature film stress and mercury probe Capacitance–Voltage measurements. The TEOS SiO 2 films show good conformality, excellent densification, low thermal stress, high breakdown voltage and low current leakage. - Highlights: • Tetraethyl orthosilicate-based oxide films were deposited for packaging application. • The oxide films deposited plasma-enhanced chemical vapor deposition (PECVD) at 400 °C. • The PECVD oxide films exhibit good step coverage. • The 400 °C PECVD oxide films exhibit low thermal stress and current leakage. • The 400 °C PECVD oxide films show high breakdown voltage and acceptable permittivity

  19. Structure of AlAs/GaAs distributed Bragg reflector grown on Si substrate by metalorganic chemical vapor deposition

    OpenAIRE

    Takashi, Egawa; Takashi, Jimbo; Masayoshi, Umeno

    1995-01-01

    A vertical‐cavity surface‐emitting laser diode with 20 pairs of AlAs/GaAs distributed Bragg reflectors (DBRs) has been grown on a Si substrate using metalorganic chemical vapor deposition. Interfacial roughness and compositional profile of the AlAs/GaAs DBR structure were studied by cross‐sectional scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Auger electron spectroscopy. Cross‐sectional SEM and TEM observations reveal quasi‐periodic zigzag roughness and nonu...

  20. Large area plasma-enhanced chemical vapor deposition of nanocrystalline graphite on insulator for electronic device application

    OpenAIRE

    Schmidt, Marek E.; Xu, Cigang; Cooke, Mike; Mizuta, Hiroshi; Chong, H.M.H.

    2012-01-01

    This paper reports on large area plasma-enhanced chemical vapor deposition (PECVD) of nanocrystalline graphite (NCG) on thermally grown SiO2 wafer, quartz and sapphire substrates. Grown films are evaluated using Raman spectroscopy, ellipsometry, scanning electron microscopy (SEM) and atomic force microscopy (AFM). Electrical characterization and optical transmission measurementsindicate promising properties of this material for use as transparent electrodes and for electronic device applicati...

  1. Relationship between heating atmosphere and copper foil impurities during graphene growth via low pressure chemical vapor deposition

    OpenAIRE

    Çelik, Yasemin; Escoffier, Walter; Yang, Ming; Flahaut, Emmanuel; Suvacı, Ender

    2016-01-01

    International audience; Low-pressure chemical vapor deposition synthesis of graphene films on two different Cu foils, with different surface oxygen and carbon contents, was performed by controlling H2 and/or Ar flow rates during heating. The influences of heating atmosphere on the final impurity level, quality of the synthesized graphene films and thickness uniformity were investigated depending on Cu foil impurities. Heating of carbon-rich, but oxygen-poor Cu foil in H2 environment resulted ...

  2. Superhydrophobic photocatalytic surfaces through direct incorporation of titania nanoparticles into a polymer matrix by aerosol assisted chemical vapor deposition.

    Science.gov (United States)

    Crick, Colin R; Bear, Joseph C; Kafizas, Andreas; Parkin, Ivan P

    2012-07-10

    A new class of superhydrophobic photocatalytic surfaces that are self-cleaning through light-induced photodegradation and the Lotus effect are presented. The films are formed in a single-step aerosol-assisted chemical vapor deposition (AACVD) process. The films are durable and show no degradation on continuous exposure to UV-C radiation. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Near-equilibrium chemical vapor deposition of high-quality single-crystal graphene directly on various dielectric substrates.

    Science.gov (United States)

    Chen, Jianyi; Guo, Yunlong; Jiang, Lili; Xu, Zhiping; Huang, Liping; Xue, Yunzhou; Geng, Dechao; Wu, Bin; Hu, Wenping; Yu, Gui; Liu, Yunqi

    2014-03-05

    By using near-equilibrium chemical vapor deposition, it is demonstrated that high-quality single-crystal graphene can be grown on dielectric substrates. The maximum size is about 11 μm. The carrier mobility can reach about 5650 cm(2) V(-1) s(-1) , which is comparable to those of some metal-catalyzed graphene crystals, reflecting the good quality of the graphene lattice. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Tuning of electrical and structural properties of indium oxide films grown by metal organic chemical vapor deposition

    International Nuclear Information System (INIS)

    Wang, Ch.Y.; Cimalla, V.; Romanus, H.; Kups, Th.; Niebelschuetz, M.; Ambacher, O.

    2007-01-01

    Tuning of structural and electrical properties of indium oxide (In 2 O 3 ) films by means of metal organic chemical vapor deposition is demonstrated. Phase selective growth of rhombohedral In 2 O 3 (0001) and body-centered cubic In 2 O 3 (001) polytypes on (0001) sapphire substrates was obtained by adjusting the substrate temperature and trimethylindium flow rate. The specific resistance of the as-grown films can be tuned by about two orders of magnitude by varying the growth conditions

  5. In-situ growth of YBCO high- Tc superconducting thin films by plasma-enhanced metalorganic chemical vapor deposition

    Science.gov (United States)

    Zhao, J.; Chern, C. S.; Li, Y. Q.; Noh, D. W.; Norris, P. E.; Zawadzki, P.; Kear, B.; Gallois, B.

    1991-01-01

    Highly c-axis oriented, highly dense, low carbon YBa 2Cu 3O x superconducting thin films have been formed in-situ at a reduced substrate temperature as low as 570°C by a novel plasma enhanced metalorganic chemical vapor deposition process. Superconducting YBa 2Cu 3O x thin films, having a zero resistance transition temperature of 82 K and critical current density of 10 4A/cm 2 at 70 K have been directly deposited on sapphire substrates by such a process.

  6. ZnO/SnO2 nanoflower based ZnO template synthesized by thermal chemical vapor deposition

    International Nuclear Information System (INIS)

    Sin, N. D. Md.; Amalina, M. N.; Ismail, Ahmad Syakirin; Shafura, A. K.; Ahmad, Samsiah; Mamat, M. H.; Rusop, M.

    2016-01-01

    The ZnO/SnO 2 nanoflower like structures was grown on a glass substrate deposited with seed layer using thermal chemical vapor deposition (CVD) with combining two source materials. The ZnO/SnO 2 nanoflower like structures had diameter in the range 70 to 100 nm. The atomic percentage of ZnO nanoparticle , SnO 2 nanorods and ZnO/SnO 2 nanoflower was taken using EDS. Based on the FESEM observations, the growth mechanism is applied to describe the growth for the synthesized nanostructures.

  7. ZnO/SnO{sub 2} nanoflower based ZnO template synthesized by thermal chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Sin, N. D. Md., E-mail: diyana0366@johor.uitm.edu.my; Amalina, M. N., E-mail: amalina0942@johor.uitm.edu.my [NANO-ElecTronic Centre, Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Fakulti Kejuruteraan Elektrik, Universiti Teknologi MARA Cawangan Johor, Kampus Pasir Gudang, 81750 Masai, Johor (Malaysia); Ismail, Ahmad Syakirin, E-mail: kyrin-samaxi@yahoo.com; Shafura, A. K., E-mail: shafura@ymail.com; Ahmad, Samsiah, E-mail: samsiah.ahmad@johor.uitm.edu.my; Mamat, M. H., E-mail: mhmamat@salam.uitm.edu.my [NANO-ElecTronic Centre, Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Rusop, M., E-mail: rusop@salam.uitm.edu.my [NANO-ElecTronic Centre, Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); NANO-SciTech Centre (NST), Institute of Science (IOS), Universiti Teknologi MARA - UiTM, 40450 Shah Alam, Selangor (Malaysia)

    2016-07-06

    The ZnO/SnO{sub 2} nanoflower like structures was grown on a glass substrate deposited with seed layer using thermal chemical vapor deposition (CVD) with combining two source materials. The ZnO/SnO{sub 2} nanoflower like structures had diameter in the range 70 to 100 nm. The atomic percentage of ZnO nanoparticle , SnO{sub 2} nanorods and ZnO/SnO{sub 2} nanoflower was taken using EDS. Based on the FESEM observations, the growth mechanism is applied to describe the growth for the synthesized nanostructures.

  8. Magmatic Vapor Phase Transport of Copper in Reduced Porphyry Copper-Gold Deposits: Evidence From PIXE Microanalysis of Fluid Inclusions

    Science.gov (United States)

    Rowins, S. M.; Yeats, C. J.; Ryan, C. G.

    2002-05-01

    Nondestructive proton-induced X-ray emission (PIXE) studies of magmatic fluid inclusions in granite-related Sn-W deposits [1] reveal that copper transport out of reduced felsic magmas is favored by low-salinity vapor and not co-existing high-salinity liquid (halite-saturated brine). Copper transport by magmatic vapor also has been documented in oxidized porphyry Cu-Au deposits, but the magnitude of Cu partitioning into the vapor compared to the brine generally is less pronounced than in the reduced magmatic Sn-W systems [2]. Consideration of these microanalytical data leads to the hypothesis that Cu and, by inference, Au in the recently established "reduced porphyry copper-gold" (RPCG) subclass should partition preferentially into vapor and not high-salinity liquid exsolving directly from fluid-saturated magmas [3-4]. To test this hypothesis, PIXE microanalysis of primary fluid inclusions in quartz-sulfide (pyrite, pyrrhotite & chalcopyrite) veins from two RPCG deposits was undertaken using the CSIRO-GEMOC nuclear microprobe. PIXE microanalysis for the ~30 Ma San Anton deposit (Mexico) was done on halite-saturated aqueous brine (deposit (W. Australia) was done on halite-saturated "aqueous" inclusions, which contain a small (deposits of the new RPCG subclass demonstrate the greater potential of these systems, compared to the classically oxidized porphyry Cu-Au systems, to transport Cu and probably precious metals in a magmatic aqueous vapor phase. These PIXE data also support the possibility that Cu partitions preferentially into an immiscible CO2-rich magmatic fluid. References: [1] Heinrich, C.A. et al. (1992) Econ. Geol., 87, 1566-1583. [2] Heinrich, C.A. et al. (1999) Geology, 27, 755-758. [3] Rowins, S.M. (2000) Geology, 28, 491-494. [4] Rowins, S.M. (2000) The Gangue, GAC-MDD Newsletter, 67, 1-7 (www.gac.ca). [5] Rowins, S.M. et al. (1993) Geol. Soc. Australia Abs., 34, 68-70.

  9. Plasma-enhanced chemical vapor deposition of n-heptane and methyl methacrylate for potential cell alignment applications.

    Science.gov (United States)

    Steinbach, Annina; Tautzenberger, Andrea; Schaller, Andreas; Kalytta-Mewes, Andreas; Tränkle, Sebastian; Ignatius, Anita; Volkmer, Dirk

    2012-10-24

    Plasma-enhanced chemical vapor deposited polymers (plasma polymers) are promising candidates for biomaterials applications. In the present study, plasma deposition as a fast and easily scalable method was adapted to deposit coatings from n-heptane and methyl methacrylate monomers onto glass substrates. Linear patterns with line and groove widths between 1.25 and 160 μm were introduced by degrative UV-lithography for cell alignment. Differential interference contrast optical microscopy, profilometry and atomic force microscopy revealed that the patterned surfaces had a smooth, homogeneous appearance and a pattern height of 8 and 45 nm for plasma deposited n-heptane and methyl methacrylate, respectively. UV-lithography increased the oxygen content on the surface drastically as shown by X-ray photoelectron spectroscopy. After immersion in simulated body fluid for 21 days, the pattern was still intact, and the ester groups were also maintained for the most part as shown by infrared spectroscopy. To test the coatings' potential applicability for biomaterial surfaces in a preliminary experiment, we cultured murine preosteoblastic MC3T3-E1 cells on these coatings. Light and electron microscopically, a normal spindle-shaped and aligned cell morphology was observed. At the mRNA level, cells showed no signs of diminished proliferation or elevated expression of apoptosis markers. In conclusion, plasma-enhanced chemical vapor deposited polymers can be patterned with a fast and feasible method and might be suitable materials to guide cell alignment.

  10. Synthesis of chemical vapor deposition graphene on tantalum wire for supercapacitor applications

    Energy Technology Data Exchange (ETDEWEB)

    Li, Mingji, E-mail: limingji@163.com [Tianjin Key Laboratory of Film Electronic and Communicate Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin 300384 (China); Guo, Wenlong [Tianjin Key Laboratory of Film Electronic and Communicate Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin 300384 (China); Li, Hongji, E-mail: hongjili@yeah.net [Tianjin Key Laboratory of Organic Solar Cells and Photochemical Conversion, School of Chemistry and Chemical Engineering, Tianjin University of Technology, Tianjin 300384 (China); Xu, Sheng [School of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072 (China); Qu, Changqing; Yang, Baohe [Tianjin Key Laboratory of Film Electronic and Communicate Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin 300384 (China)

    2014-10-30

    Highlights: • The capacitance of graphene/tantalum (Ta) wire electrodes is firstly reported. • Graphene was grown on the Ta surface by hot-filament chemical vapor deposition. • Graphene/Ta wire structure is favorable for fast ion and electron transfer. • The graphene/Ta wire electrode shows high capacitive properties. - Abstract: This paper studies the synthesis and electrochemical characterization of graphene/tantalum (Ta) wires as high-performance electrode material for supercapacitors. Graphene on Ta wires is prepared by the thermal decomposition of methane under various conditions. The graphene nanosheets on the Ta wire surface have an average thickness of 1.3–3.4 nm and consist typically of a few graphene monolayers, and TaC buffer layers form between the graphene and Ta wire. A capacitor structure is fabricated using graphene/Ta wire with a length of 10 mm and a diameter of 0.6 mm as the anode and Pt wire of the same size as the cathode. The electrochemical behavior of the graphene/Ta wires as supercapacitor electrodes is characterized by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy in 1 M Na{sub 2}SO{sub 4} aqueous electrolyte. The as-prepared graphene/Ta electrode has highest capacitance of 345.5 F g{sup −1} at current density of 0.5 A g{sup −1}. The capacitance remains at about 84% after 1000 cycles at 10 A g{sup −1}. The good electrochemical performance of the graphene/Ta wire electrode is attributed to the unique nanostructural configuration, high electrical conductivity, and large specific surface area of the graphene layer. This suggests that graphene/Ta wire electrode materials have potential applications in high-performance energy storage devices.

  11. Ultraclean and large-area monolayer hexagonal boron nitride on Cu foil using chemical vapor deposition.

    Science.gov (United States)

    Wen, Yao; Shang, Xunzhong; Dong, Ji; Xu, Kai; He, Jun; Jiang, Chao

    2015-07-10

    Atomically thin hexagonal boron nitride (h-BN) has been demonstrated to be an excellent dielectric layer as well as an ideal van der Waals epitaxial substrate for fabrication of two-dimensional (2D) atomic layers and their vertical heterostructures. Although many groups have obtained large-scale monolayer h-BN through low pressure chemical vapor deposition (LPCVD), it is still a challenge to grow clean monolayers without the reduction of domain size. Here we report the synthesis of large-area (4 × 2 cm(2)) high quality monolayer h-BN with an ultraclean and unbroken surface on copper foil by using LPCVD. A detailed investigation of the key factors affecting growth and transfer of the monolayer was carried out in order to eliminate the adverse effects of impurity particles. Furthermore, an optimized transfer approach allowed the nondestructive and clean transfer of the monolayer from copper foil onto an arbitrary substrate, including a flexible substrate, under mild conditions. Atomic force microscopy indicated that the root-mean-square (RMS) roughness of the monolayer h-BN on SiO2 was less than 0.269 nm for areas with fewer wrinkles. Selective area electron diffraction analysis of the h-BN revealed a pattern of hexagonal diffraction spots, which unambiguously demonstrated its highly crystalline character. Our work paves the way toward the use of ultraclean and large-area monolayer h-BN as the dielectric layer in the fabrication of high performance electronic and optoelectronic devices for novel 2D atomic layer materials.

  12. Growth of thick p-type SiC epitaxial layers by halide chemical vapor deposition

    Science.gov (United States)

    Fanton, M. A.; Weiland, B. E.; Redwing, J. M.

    2008-08-01

    The halide chemical vapor deposition process for single-crystal SiC achieves growth rates over 200 μm/h at temperatures approaching 2000 °C. This work examines the conditions required to produce 80-100-μm-thick heavily p-type doped layers on 4H-SiC substrates by using boron trichloride and trimethylaluminum at high growth temperatures. Dopant incorporation as a function of the dopant concentration in the growth ambient was evaluated by secondary ion mass spectrometry (SIMS). The maximum Al and B concentrations achieved were 5×10 17 and 4×10 19 atoms/cm 3, respectively. Low Al incorporation efficiency was attributed to the high growth temperature and reaction of Al with Cl to form volatile chloride species. Aluminum incorporation was consistent with incorporation as a simple solid solution, while B incorporation exhibited a much stronger interaction with the SiC matrix. Aluminum incorporation was found to be an order of magnitude higher on the Si-face of the substrate, while B incorporation was essentially the same on both the Si-face and C-face. Aluminum incorporation was increased by a factor of five as the C/Si ratio increased from 0.42 to 0.86, while boron incorporation showed no sensitivity to the C/Si ratio. The B concentrations measured by SIMS were of the same magnitude as the net acceptor concentrations estimated from capacitance-voltage measurements, indicating a significant fraction of the B dopant was activated.

  13. Ultraclean and large-area monolayer hexagonal boron nitride on Cu foil using chemical vapor deposition

    Science.gov (United States)

    Wen, Yao; Shang, Xunzhong; Dong, Ji; Xu, Kai; He, Jun; Jiang, Chao

    2015-07-01

    Atomically thin hexagonal boron nitride (h-BN) has been demonstrated to be an excellent dielectric layer as well as an ideal van der Waals epitaxial substrate for fabrication of two-dimensional (2D) atomic layers and their vertical heterostructures. Although many groups have obtained large-scale monolayer h-BN through low pressure chemical vapor deposition (LPCVD), it is still a challenge to grow clean monolayers without the reduction of domain size. Here we report the synthesis of large-area (4 × 2 cm2) high quality monolayer h-BN with an ultraclean and unbroken surface on copper foil by using LPCVD. A detailed investigation of the key factors affecting growth and transfer of the monolayer was carried out in order to eliminate the adverse effects of impurity particles. Furthermore, an optimized transfer approach allowed the nondestructive and clean transfer of the monolayer from copper foil onto an arbitrary substrate, including a flexible substrate, under mild conditions. Atomic force microscopy indicated that the root-mean-square (RMS) roughness of the monolayer h-BN on SiO2 was less than 0.269 nm for areas with fewer wrinkles. Selective area electron diffraction analysis of the h-BN revealed a pattern of hexagonal diffraction spots, which unambiguously demonstrated its highly crystalline character. Our work paves the way toward the use of ultraclean and large-area monolayer h-BN as the dielectric layer in the fabrication of high performance electronic and optoelectronic devices for novel 2D atomic layer materials.

  14. Characterization and electrolytic cleaning of poly(methyl methacrylate) residues on transferred chemical vapor deposited graphene.

    Science.gov (United States)

    Sun, Jianbo; Finklea, Harry O; Liu, Yuxin

    2017-03-24

    Poly(methyl methacrylate) (PMMA) residue has long been a critical challenge for practical applications of the transferred chemical vapor deposited (CVD) graphene. Thermal annealing is empirically used for the removal of the PMMA residue; however experiments imply that there are still small amounts of residues left after thermal annealing which are hard to remove with conventional methods. In this paper, the thermal degradation of the PMMA residue upon annealing was studied by Raman spectroscopy. The study reveals that post-annealing residues are generated by the elimination of methoxycarbonyl side chains in PMMA and are believed to be absorbed on graphene via the π-π interaction between the conjugated unsaturated carbon segments and graphene. The post-annealing residues are difficult to remove by further annealing in a non-oxidative atmosphere due to their thermal and chemical stability. An electrolytic cleaning method was shown to be effective in removing these post-annealing residues while preserving the underlying graphene lattice based on Raman spectroscopy and atomic force microscopy studies. Additionally, a solution-gated field effect transistor was used to study the transport properties of the transferred CVD graphene before thermal annealing, after thermal annealing, and after electrolytic cleaning, respectively. The results show that the carrier mobility was significantly improved, and that the p-doping was reduced by removing PMMA residues and post-annealing residues. These studies provide a more in-depth understanding on the thermal annealing process for the removal of the PMMA residues from transferred CVD graphene and a new approach to remove the post-annealing residues, resulting in a residue-free graphene.

  15. Three-dimensional kinetic Monte Carlo simulations of diamond chemical vapor deposition.

    Science.gov (United States)

    Rodgers, W J; May, P W; Allan, N L; Harvey, J N

    2015-06-07

    A three-dimensional kinetic Monte Carlo model has been developed to simulate the chemical vapor deposition of a diamond (100) surface under conditions used to grow single-crystal diamond (SCD), microcrystalline diamond (MCD), nanocrystalline diamond (NCD), and ultrananocrystalline diamond (UNCD) films. The model includes adsorption of CHx (x = 0, 3) species, insertion of CHy (y = 0-2) into surface dimer bonds, etching/desorption of both transient adsorbed species and lattice sidewalls, lattice incorporation, and surface migration but not defect formation or renucleation processes. A value of ∼200 kJ mol(-1) for the activation Gibbs energy, ΔG(‡) etch, for etching an adsorbed CHx species reproduces the experimental growth rate accurately. SCD and MCD growths are dominated by migration and step-edge growth, whereas in NCD and UNCD growths, migration is less and species nucleate where they land. Etching of species from the lattice sidewalls has been modelled as a function of geometry and the number of bonded neighbors of each species. Choice of appropriate parameters for the relative decrease in etch rate as a function of number of neighbors allows flat-bottomed etch pits and/or sharp-pointed etch pits to be simulated, which resemble those seen when etching diamond in H2 or O2 atmospheres. Simulation of surface defects using unetchable, immobile species reproduces other observed growth phenomena, such as needles and hillocks. The critical nucleus for new layer growth is 2 adjacent surface carbons, irrespective of the growth regime. We conclude that twinning and formation of multiple grains rather than pristine single-crystals may be a result of misoriented growth islands merging, with each island forming a grain, rather than renucleation caused by an adsorbing defect species.

  16. Chemical vapor deposition on chabazite (CHA) zeolite membranes for effective post-combustion CO2 capture.

    Science.gov (United States)

    Kim, Eunjoo; Lee, Taehee; Kim, Hyungmin; Jung, Won-Jin; Han, Doug-Young; Baik, Hionsuck; Choi, Nakwon; Choi, Jungkyu

    2014-12-16

    Chabazite (CHA) zeolites with a pore size of 0.37 × 0.42 nm(2) are expected to separate CO2 (0.33 nm) from larger N2 (0.364 nm) in postcombustion flue gases by recognizing their minute size differences. Furthermore, the hydrophobic siliceous constituent in CHA membranes can allow for maintaining the CO2/N2 separation performance in the presence of H2O in contrast with the CO2 affinity-based membranes. In an attempt to increase the molecular sieving ability, the pore mouth size of all silica CHA (Si-CHA) particles was reduced via the chemical vapor deposition (CVD) of a silica precursor (tetraethyl orthosilicate). Accordingly, an increase of the CVD treatment duration decreased the penetration rate of CO2 into the CVD-treated Si-CHA particles. Furthermore, the CVD process was applied to siliceous CHA membranes in order to improve their CO2/N2 separation performance. Compared to the intact CHA membranes, the CO2/N2 maximum separation factor (max SF) for CVD-treated CHA membranes was increased by ∼ 2 fold under dry conditions. More desirably, the CO2/N2 max SF was increased by ∼ 3 fold under wet conditions at ∼ 50 °C, a representative temperature of the flue gas stream. In fact, the presence of H2O in the feed disfavored the permeation of N2 more than that of CO2 through CVD-modified CHA membranes and thus, contributed to the increased CO2/N2 separation factor.

  17. Simplified efficient phosphorescent organic light-emitting diodes by organic vapor phase deposition

    Science.gov (United States)

    Pfeiffer, P.; Beckmann, C.; Stümmler, D.; Sanders, S.; Simkus, G.; Heuken, M.; Vescan, A.; Kalisch, H.

    2017-12-01

    The most efficient phosphorescent organic light-emitting diodes (OLEDs) are comprised of complex stacks with numerous organic layers. State-of-the-art phosphorescent OLEDs make use of blocking layers to confine charge carriers and excitons. On the other hand, simplified OLEDs consisting of only three organic materials have shown unexpectedly high efficiency when first introduced. This was attributed to superior energy level matching and suppressed external quantum efficiency (EQE) roll-off. In this work, we study simplified OLED stacks, manufactured by organic vapor phase deposition, with a focus on charge balance, turn-on voltage (Von), and efficiency. To prevent electrons from leaking through the device, we implemented a compositionally graded emission layer. By grading the emitter with the hole transport material, charge confinement is enabled without additional blocking layers. Our best performing organic stack is composed of only three organic materials in two layers including the emitter Ir(ppy)3 and yields a Von of 2.5 V (>1 cd/m2) and an EQE of 13% at 3000 cd/m2 without the use of any additional light extraction techniques. Changes in the charge balance, due to barrier tuning or adjustments in the grading parameters and layer thicknesses, are clearly visible in the current density-voltage-luminance (J-V-L) measurements. As charge injection at the electrodes and organic interfaces is of great interest but difficult to investigate in complex device structures, we believe that our simplified organic stack is not only a potent alternative to complex state-of-the-art OLEDs but also a well suited test vehicle for experimental studies focusing on the modification of the electrode-organic semiconductor interface.

  18. Plasma assisted chemical vapor deposited tantalum silicon nitride thin films for applications in nanoscale devices

    Science.gov (United States)

    Zeng, Wanxue

    The scaling issues resulting from diminishing device feature sizes have prompted the investigation of alternative materials and deposition techniques for copper diffusion barrier applications. As device sizes shrink to sub 100-nm technology nodes, the allowable copper diffusion barrier thickness falls to less than 10 nm. In this respect, novel materials are needed to stop copper diffusion into surrounding materials. TaSiN has been regarded as one of the most promising materials for copper diffusion barrier applications, owing to its excellent thermal stability, amorphous structure, and low resistivity. In this respect, a plasma assisted chemical vapor deposition (PACVD) process using TaF5, SiI4, N2, H2, and in-situ radio frequency (RF) plasma was optimized for depositing ultrathin TaSiN films, employing a design of experiments (DOE) approach. Film properties were characterized using Rutherford backscattering spectrometry (RBS), nuclear reaction analysis (NRA), Auger electron spectroscopy (AES), x-ray diffraction (XRD), atomic force microscopy (AFM), four-point resistivity probe, and cross-section scanning electron microscopy (CS-SEM). The TaSiN films, deposited via optimized process conditions, exhibited low resistivity, low contamination levels, smooth surface morphology, good step coverage, excellent thermal stability, and amorphous structure. The copper diffusion barrier performance of optimized PACVD TaSiN films was assessed in Cu/TaSiN/Si structures using traditional high temperature annealing methods and in Cu/TaSiN/SiO2/Si structures using a triangular voltage sweep (TVS) method. The results from the former technique show that the diffusion barrier performance of TaSiN films with higher silicon concentration, corresponding to a more prevalent amorphous structure, leads to worse Cu diffusion barrier performance. The results from the TaSiN barrier testing also show that thinner TaSiN films (≤5 nm) performed better as Cu diffusion barriers than thicker Ta

  19. Aluminum-silicon coatings on austenitic stainless steel (AISI 304 and 317 deposited by chemical vapor deposition in a fluidized bed

    Directory of Open Access Journals (Sweden)

    José Luddey Marulanda Arevalo

    2014-05-01

    Full Text Available Aluminum-silicon coatings were deposited onto stainless steels AISI 304 and AISI 317. The deposition was performed at 540°C with a ratio of active gases HCl/H2 of 1/15.3; argon was used as a carrier gas. The bed of the FBR-CVD process consisted of 2.5 g aluminum powder, 7.5 g silicon powder and 90 g alumina. After the coatings were deposited, each sample was given a heat treatment to improve its mechanical properties and oxidation behavior by diffusing the alloying elements. Thermodynamic simulation was performed with Thermo-Calc software to investigate the composition of the deposited material. The coated and uncoated specimens were exposed to temperatures of 750ºC in an atmosphere where the vapor was transported to the samples using a flow of N2 of 40 ml/min and 100% water vapor (H2O. The coated specimens gained little weight during the thousand hours of exposure and will thus guard against a corrosive attack compared to the uncoated substrates. In addition, the coated stainless steels show an oxidation rate with a logarithmic trend while the uncoated steel oxidation rate showed a linear trend.

  20. 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.

  1. Effect of microstructure on the near-failure detonation behavior of vapor-deposited pentaerythritol tetranitrate (PETN) films

    Science.gov (United States)

    Knepper, Robert; Forrest, Eric; Marquez, Michael; Tappan, Alexander

    2017-06-01

    Physical vapor deposition is an attractive method to produce sub-millimeter explosive samples with precisely controlled microstructure and geometry for studying detonation behavior at near-failure conditions. Pentaerythritol tetranitrate (PETN) is particularly interesting, as the microstructure of vapor-deposited films can be varied substantially by altering the surface energy of the substrate. In this work, we examine PETN films deposited in a sandwich structure with aluminum confinement, elucidating the effect of the confinement layers on the explosive thickness needed to sustain a propagating detonation. The interface energy between the PETN and aluminum can be altered depending on whether the aluminum is exposed to atmosphere prior to PETN deposition, which results in significant changes in density, preferred crystal orientation, and porosity distribution in the films. The resulting microstructures are characterized using scanning electron microscopy and x-ray diffraction. The effects of these changes in microstructure on detonation velocity and failure thickness as a function of confinement thickness are determined, providing an estimate of changes in detonation reaction kinetics with variation in microstructure. SAND2017-1750 A.

  2. Buoyancy-Driven Heat Transfer During Application of a Thermal Gradient for the Study of Vapor Deposition at Low Pressure Using and Ideal Gas

    Science.gov (United States)

    Frazier, D. O.; Hung, R. J.; Paley, M. S.; Penn, B. G.; Long, Y. T.

    1996-01-01

    A mathematical model has been developed to determine heat transfer during vapor deposition of source materials under a variety of orientations relative to gravitational accelerations. The model demonstrates that convection can occur at total pressures as low as 10-2 mm Hg. Through numerical computation, using physical material parameters of air, a series of time steps demonstrates the development of flow and temperature profiles during the course of vapor deposition. These computations show that in unit gravity vapor deposition occurs by transport through a fairly complicated circulating flow pattern when applying heat to the bottom of the vessel with parallel orientation with respect to the gravity vector. The model material parameters for air predict the effect of kinematic viscosity to be of the same order as thermal diffusivity, which is the case for Prandtl number approx. 1 fluids. Qualitative agreement between experiment and the model indicates that 6-(2-methyl-4-nitroanilino)-2,4-hexadiyn-l-ol (DAMNA) at these pressures indeed approximates an ideal gas at the experiment temperatures, and may validate the use of air physical constants. It is apparent that complicated nonuniform temperature distribution in the vapor could dramatically affect the homogeneity, orientation, and quality of deposited films. The experimental test i's a qualitative comparison of film thickness using ultraviolet-visible spectroscopy on films generated in appropriately oriented vapor deposition cells. In the case where heating of the reaction vessel occurs from the top, deposition of vapor does not normally occur by convection due to a stable stratified medium. When vapor deposition occurs in vessels heated at the bottom, but oriented relative to the gravity vector between these two extremes, horizontal thermal gradients induce a complex flow pattern. In the plane parallel to the tilt axis, the flow pattern is symmetrical and opposite in direction from that where the vessel is

  3. Synthesis of Three-dimensional Polymer Nanostructures via Chemical Vapor Deposition

    Science.gov (United States)

    Cheng, Kenneth

    Chemical vapor deposition (CVD) is a widely practiced methodology for preparing thin film polymer coatings, and the coatings can be applied to a broad range of materials, including three-dimensional solid structures and low-vapor pressure liquids. Reactive poly(p-xylylene) (PPX) coatings prepared by CVD can be used as a powerful tool for surface functionalization and bio-conjugation. The first portion of this dissertation serves to extend the use of CVD-based reactive PPX coatings as a surface functionalization strategy for the conjugation of biomolecules. Micro-structured PPX coatings having multiple surface reactive groups were fabricated. Multiple orthogonal click reactions were then employed to selectively immobilize galactose and mannobiose to the micro-structured polymer coatings. The presence of different types of carbohydrate enables lectins binding for examining ligands/cell receptor interactions. This dissertation also demonstrates the use of CVD-based reactive PPX coatings as intermediate layers to immobilize adenoviral vectors onto tissue scaffolds. The ability to tether adenoviral vectors on tissue scaffolds localizes the transduction near the scaffold surface and reduces acute toxicity and hepatic pathology cause by direct administration of the viral vector, providing a safe and efficient gene therapy delivery strategy. In the second portion of this dissertation, we explore the CVD of PPX onto surfaces coated with a thin layer of liquid crystal (LC). Instead of forming a conformal PPX coating encapsulating the LC layer, PPX assembled into an array of high-aspect ratio nanofibers inside the LC layer. The LC layer was demonstrated to act as a template where the anisotropic internal ordering of the LC facilitated the formation of nanofibers. The diameter of the nanofibers was in the range of 100 nm and could be tuned by type of LC template used, and the length of the nanofibers could be precisely controlled by varying the thickness of the LC film. The

  4. Complementary Metal Oxide Semiconductor-Compatible, High-Mobility, ⟨111⟩-Oriented GaSb Nanowires Enabled by Vapor-Solid-Solid Chemical Vapor Deposition.

    Science.gov (United States)

    Yang, Zai-Xing; Liu, Lizhe; Yip, SenPo; Li, Dapan; Shen, Lifan; Zhou, Ziyao; Han, Ning; Hung, Tak Fu; Pun, Edwin Yue-Bun; Wu, Xinglong; Song, Aimin; Ho, Johnny C

    2017-04-25

    Using CMOS-compatible Pd catalysts, we demonstrated the formation of high-mobility ⟨111⟩-oriented GaSb nanowires (NWs) via vapor-solid-solid (VSS) growth by surfactant-assisted chemical vapor deposition through a complementary experimental and theoretical approach. In contrast to NWs formed by the conventional vapor-liquid-solid (VLS) mechanism, cylindrical-shaped Pd 5 Ga 4 catalytic seeds were present in our Pd-catalyzed VSS-NWs. As solid catalysts, stoichiometric Pd 5 Ga 4 was found to have the lowest crystal surface energy and thus giving rise to a minimal surface diffusion as well as an optimal in-plane interface orientation at the seed/NW interface for efficient epitaxial NW nucleation. These VSS characteristics led to the growth of slender NWs with diameters down to 26.9 ± 3.5 nm. Over 95% high crystalline quality NWs were grown in ⟨111⟩ orientation for a wide diameter range of between 10 and 70 nm. Back-gated field-effect transistors (FETs) fabricated using the Pd-catalyzed GaSb NWs exhibit a superior peak hole mobility of ∼330 cm 2 V -1 s -1 , close to the mobility limit for a NW channel diameter of ∼30 nm with a free carrier concentration of ∼10 18 cm -3 . This suggests that the NWs have excellent homogeneity in phase purity, growth orientation, surface morphology and electrical characteristics. Contact printing process was also used to fabricate large-scale assembly of Pd-catalyzed GaSb NW parallel arrays, confirming the potential constructions and applications of these high-performance electronic devices.

  5. Zno Micro/Nanostructures Grown on Sapphire Substrates Using Low-Temperature Vapor-Trapped Thermal Chemical Vapor Deposition: Structural and Optical Properties.

    Science.gov (United States)

    Hu, Po-Sheng; Wu, Cheng-En; Chen, Guan-Lin

    2017-12-21

    In this research, the Zn(C₅H₇O₂)₂·xH₂O-based growth of ZnO micro/nanostructures in a low temperature, vapor-trapped chemical vapor deposition system was attempted to optimize structural and optical properties for potential biomedical applications. By trapping in-flow gas molecules and Zinc vapor inside a chamber tube by partially obstructing a chamber outlet, a high pressure condition can be achieved, and this experimental setup has the advantages of ease of synthesis, being a low temperature process, and cost effectiveness. Empirically, the growth process proceeded under a chamber condition of an atmospheric pressure of 730 torr, a controlled volume flow rate of input gas, N₂/O₂, of 500/500 Standard Cubic Centimeters per Minute (SCCM), and a designated oven temperature of 500 °C. Specifically, the dependence of structural and optical properties of the structures on growth duration and spatially dependent temperature were investigated utilizing scanning electron microscopy, X-ray diffraction (XRD), photoluminescence (PL), and ultraviolet-visible transmission spectroscopy. The experimental results indicate that the grown thin film observed with hexagonal structures and higher structural uniformity enables more prominent structural and optical signatures. XRD spectra present the dominant peaks along crystal planes of (002) and (101) as the main direction of crystallization. In addition, while the structures excited with laser wavelength of 325 nm emit a signature radiation around 380 nm, an ultraviolet lamp with a wavelength of 254 nm revealed distinctive photoluminescence peaks at 363.96 nm and 403.52 nm, elucidating different degrees of structural correlation as functions of growth duration and the spatial gradient of temperature. Transmittance spectra of the structures illustrate typical variation in the wavelength range of 200 nm to 400 nm, and its structural correlation is less significant when compared with PL.

  6. Zno Micro/Nanostructures Grown on Sapphire Substrates Using Low-Temperature Vapor-Trapped Thermal Chemical Vapor Deposition: Structural and Optical Properties

    Directory of Open Access Journals (Sweden)

    Po-Sheng Hu

    2017-12-01

    Full Text Available In this research, the Zn(C5H7O22·xH2O-based growth of ZnO micro/nanostructures in a low temperature, vapor-trapped chemical vapor deposition system was attempted to optimize structural and optical properties for potential biomedical applications. By trapping in-flow gas molecules and Zinc vapor inside a chamber tube by partially obstructing a chamber outlet, a high pressure condition can be achieved, and this experimental setup has the advantages of ease of synthesis, being a low temperature process, and cost effectiveness. Empirically, the growth process proceeded under a chamber condition of an atmospheric pressure of 730 torr, a controlled volume flow rate of input gas, N2/O2, of 500/500 Standard Cubic Centimeters per Minute (SCCM, and a designated oven temperature of 500 °C. Specifically, the dependence of structural and optical properties of the structures on growth duration and spatially dependent temperature were investigated utilizing scanning electron microscopy, X-ray diffraction (XRD, photoluminescence (PL, and ultraviolet-visible transmission spectroscopy. The experimental results indicate that the grown thin film observed with hexagonal structures and higher structural uniformity enables more prominent structural and optical signatures. XRD spectra present the dominant peaks along crystal planes of (002 and (101 as the main direction of crystallization. In addition, while the structures excited with laser wavelength of 325 nm emit a signature radiation around 380 nm, an ultraviolet lamp with a wavelength of 254 nm revealed distinctive photoluminescence peaks at 363.96 nm and 403.52 nm, elucidating different degrees of structural correlation as functions of growth duration and the spatial gradient of temperature. Transmittance spectra of the structures illustrate typical variation in the wavelength range of 200 nm to 400 nm, and its structural correlation is less significant when compared with PL.

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

    Science.gov (United States)

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

    2000-01-01

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

  8. The SiNx films process research by plasma-enhanced chemical vapor deposition in crystalline silicon solar cells

    Science.gov (United States)

    Chen, Bitao; Zhang, Yingke; Ouyang, Qiuping; Chen, Fei; Zhan, Xinghua; Gao, Wei

    2017-07-01

    SiNx thin film has been widely used in crystalline silicon solar cell production because of the good anti-reflection and passivation effect. We can effectively optimize the cells performance by plasma-enhanced chemical vapor deposition (PECVD) method to change deposition conditions such as temperature, gas flow ratio, etc. In this paper, we deposit a new layer of SiNx thin film on the basis of double-layers process. By changing the process parameters, the compactness of thin films is improved effectively. The NH3 passivation technology is augmented in a creative way, which improves the minority carrier lifetime. In sight of this, a significant increase is generated in the photoelectric performance of crystalline silicon solar cell.

  9. Tetrasilane and digermane for the ultra-high vacuum chemical vapor deposition of SiGe alloys

    International Nuclear Information System (INIS)

    Hart, John; Hazbun, Ramsey; Eldridge, David; Hickey, Ryan; Fernando, Nalin; Adam, Thomas; Zollner, Stefan; Kolodzey, James

    2016-01-01

    Tetrasilane and digermane were used to grow epitaxial silicon germanium layers on silicon substrates in a commercial ultra-high vacuum chemical vapor deposition tool. Films with concentrations up to 19% germanium were grown at temperatures from 400 °C to 550 °C. For all alloy compositions, the growth rates were much higher compared to using mono-silane and mono-germane. The quality of the material was assessed using X-ray diffraction, atomic force microscopy, and spectroscopic ellipsometry; all indicating high quality epitaxial films with low surface roughness suitable for commercial applications. Studies of the decomposition kinetics with regard to temperature were performed, revealing an unusual growth rate maximum between the high and low temperature deposition regimes. - Highlights: • Higher order precursors tetrasilane and digermane • Low temperature deposition • Thorough film characterization with temperature • Arrhenius growth rate peak

  10. Multi-Layer Polymer Light-Emitting Diodes Prepared by Vapor Deposition Polymerization of Polyazomethine Thin Film

    Science.gov (United States)

    Itabashi, Atsushi; Fukushima, Masao; Murata, Hideyuki

    2008-02-01

    A novel poly(azomethine) (PAM) thin film deposited by vapor deposition polymerization (VDP) process was used in the emissive layer of polymer light-emitting diodes (PLEDs). 1,4-Bis(4-formylstyryl)benzene (BFSB) and 4,4''-diamino-(1,1',4',1'')-terphenyl (DAT) were co-deposited to form PAM thin films at various substrate temperatures. Fluorescent quantum yield of novel PAM synthesized by using BFSB monomer increased one order of magnitude compared with the previous report. PLEDs with the device structure of indium-tin oxide (ITO)/poly(3,4-ethylene dioxythiophene) doped with poly(styrene sulfonic acid) (PEDOT:PSS) (100 nm)/PAM (140 nm)/LiF (0.5 nm)/Al (80 nm) exhibited of electroluminescence from the PAM layer for the first time. The characteristics of PLEDs suggest the electron mobility of PAM is higher than hole mobility.

  11. Dual comb-type electrodes as a plasma source for very high frequency plasma enhanced chemical vapor deposition

    International Nuclear Information System (INIS)

    Hwang, Doo Sup; Lee, Seung Yoon; Lee, Heon Min; Kim, Sang Jin; Kim, Gil Jun

    2010-01-01

    Dual comb-type electrodes were developed as a plasma source in very high frequency (VHF) plasma enhanced chemical vapor deposition system for uniform deposition of silicon films. Two VHF powers introduced to each electrode produced parallel plasma bands, and their positions could be changed by manipulating the phase difference between the supplied VHF waves. Excitation frequency was 80 MHz. The maximum plasma density using this plasma source was 1.5 x 10 10 /cm 3 and the electron temperature was around 2 eV with input power of 2.5 kW, which were measured by double tip Langmuir probe. The uniformity of deposition rate under ± 13% was achieved on 1 m 2 area with optimal plasma conditions.

  12. Amorphous fluorocarbon polymer (a-C:F) films obtained by plasma enhanced chemical vapor deposition from perfluoro-octane (C8F18) vapor I: Deposition, morphology, structural and chemical properties

    International Nuclear Information System (INIS)

    Biloiu, Costel; Biloiu, Ioana Arabela; Sakai, Yosuke; Suda, Yoshiyuki; Ohta, Akitsugu

    2004-01-01

    The method of obtaining amorphous fluorocarbon polymer (a-C:F) films by plasma enhanced chemical vapor deposition in a capacitively coupled, 13.56 MHz reactor, from a new monomer, namely perfluoro-octane (C 8 F 18 ) vapor, is presented. For monomer pressure ranging from 0.2 to 1 Torr and input power density from 0.15 to 0.85 W/cm 3 , the maximum deposition rate reached 300 nm/min, while 10% monomer dilution with argon led to a deposition rate of 200 nm/min. The film surface and bulk morphologies, chemical and structural compositions were investigated using scanning electron microscopy, x-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. It was revealed that the films have a dense and compact structure. The fluorine to carbon ratio (F/C) of the films was between 1.57 and 1.75, and the degree of cross-linking was between 55% and 58%. The relative amount of perfluoroalkyl (CF 2 ) groups in the films was 29%. The FTIR spectra showed absorption bands corresponding to the different vibrational modes of CF, CF 2 , and CF 3 moieties

  13. Structural and optical properties of silicon thin-films deposited by hot-wire chemical vapor deposition: The effects of silane concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Panchal, A.K. [Electrical Engineering Department, S.V. National Institute of Technology, Ichchhanath, Surat 395007 (India); Beladiya, Vivek [Department of Applied Physics, S.V. National Institute of Technology, Ichchhanath, Surat 395007 (India); Kheraj, Vipul, E-mail: vipulkheraj@gmail.com [Department of Applied Physics, S.V. National Institute of Technology, Ichchhanath, Surat 395007 (India)

    2013-09-02

    In this paper, the structural and optical properties of a series of silicon (Si) thin-films deposited using hot-wire chemical vapor deposition with different silane concentrations (SCs) are presented. All the films are characterized by Raman spectroscopy, scanning electron microscopy (SEM) and photoluminescence (PL). In the Raman analysis, the first order and specifically the second order Raman spectra indicate increase in crystalline grain size as well as crystalline volume fraction in the films with a reduction in SC, which is also confirmed by the SEM analysis. At the higher SC, the Si microcrystalline grains get embedded in the nanocrystalline Si network. The Gaussian fitted peaks in the PL analysis reveal the emission due to either band to band tail-state transitions or tail-state to mid-gap defect-state transitions due to Si-dangling bonds present in the films. - Highlights: • Growth of silicon (Si) thin-films using Hot-Wire Chemical Vapor Deposition. • Scanning Electron Microscopy, Raman and Photoluminescence Spectropscopy characterization. • Increment in Si crystalline volume fraction with decrease in Silane concentration. • Microcrystalline Si grains embedded in nanocrystalline Si tissues.

  14. Cu-Al alloy formation by thermal annealing of Cu/Al multilayer films deposited by cyclic metal organic chemical vapor deposition

    Science.gov (United States)

    Moon, Hock Key; Yoon, Jaehong; Kim, Hyungjun; Lee, Nae-Eung

    2013-05-01

    One of the most important issues in future Cu-based interconnects is to suppress the resistivity increase in the Cu interconnect line while decreasing the line width below 30 nm. For the purpose of mitigating the resistivity increase in the nanoscale Cu line, alloying Cu with traces of other elements is investigated. The formation of a Cu alloy layer using chemical vapor deposition or electroplating has been rarely studied because of the difficulty in forming Cu alloys with elements such as Al. In this work, Cu-Al alloy films were successfully formed after thermal annealing of Cu/Al multilayers deposited by cyclic metal-organic chemical vapor deposition (C-MOCVD). After the C-MOCVD of Cu/Al multilayers without gas phase reaction between the Cu and Al precursors in the reactor, thermal annealing was used to form Cu-Al alloy films with a small Al content fraction. The resistivity of the alloy films was dependent on the Al precursor delivery time and was lower than that of the aluminum-free Cu film. No presence of intermetallic compounds were detected in the alloy films by X-ray diffraction measurements and transmission electron spectroscopy.

  15. Characteristics of ultra low-k nanoporous and fluorinated silica based films prepared by plasma enhanced chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Abbasi-Firouzjah, M. [Laser and Plasma Research Institute, Shahid Beheshti University G.C., Evin, Tehran 1983963113 (Iran, Islamic Republic of); Shokri, B. [Laser and Plasma Research Institute, Shahid Beheshti University G.C., Evin, Tehran 1983963113 (Iran, Islamic Republic of); Physics Department, Shahid Beheshti University G.C., Evin, Tehran (Iran, Islamic Republic of)

    2013-12-07

    Low dielectric constant (low-k) silica based films were deposited on p-type silicon and polycarbonate substrates by radio frequency (RF) plasma enhanced chemical vapor deposition method at low temperature. A mixture of tetraethoxysilane vapor, oxygen, and tetrafluoromethane (CF{sub 4}) was used for the deposition of the films in forms of two structures called as SiO{sub x}C{sub y} and SiO{sub x}C{sub y}F{sub z}. Properties of the films were controlled by amount of porosity and fluorine content in the film matrix. The influence of RF power and CF{sub 4} flow on the elemental composition, deposition rate, surface roughness, leakage current, refractive index, and dielectric constant of the films were characterized. Moreover, optical emission spectroscopy was applied to monitor the plasma process at the different parameters. Electrical characteristics of SiO{sub x}C{sub y} and SiO{sub x}C{sub y}F{sub z} films with metal-oxide-semiconductor structure were investigated using current-voltage analysis to measure the leakage current and breakdown field, as well as capacitance-voltage analysis to obtain the film's dielectric constant. The results revealed that SiO{sub x}C{sub y} films, which are deposited at lower RF power produce more leakage current, meanwhile the dielectric constant and refractive index of these films decreased mainly due to the more porosity in the film structure. By adding CF{sub 4} in the deposition process, fluorine, the most electronegative and the least polarized atom, doped into the silica film and led to decrease in the refractive index and the dielectric constant. In addition, no breakdown field was observed in the electrical characteristics of SiO{sub x}C{sub y}F{sub z} films and the leakage current of these films reduced by increment of the CF{sub 4} flow.

  16. Characteristics of ultra low-k nanoporous and fluorinated silica based films prepared by plasma enhanced chemical vapor deposition

    Science.gov (United States)

    Abbasi-Firouzjah, M.; Shokri, B.

    2013-12-01

    Low dielectric constant (low-k) silica based films were deposited on p-type silicon and polycarbonate substrates by radio frequency (RF) plasma enhanced chemical vapor deposition method at low temperature. A mixture of tetraethoxysilane vapor, oxygen, and tetrafluoromethane (CF4) was used for the deposition of the films in forms of two structures called as SiOxCy and SiOxCyFz. Properties of the films were controlled by amount of porosity and fluorine content in the film matrix. The influence of RF power and CF4 flow on the elemental composition, deposition rate, surface roughness, leakage current, refractive index, and dielectric constant of the films were characterized. Moreover, optical emission spectroscopy was applied to monitor the plasma process at the different parameters. Electrical characteristics of SiOxCy and SiOxCyFz films with metal-oxide-semiconductor structure were investigated using current-voltage analysis to measure the leakage current and breakdown field, as well as capacitance-voltage analysis to obtain the film's dielectric constant. The results revealed that SiOxCy films, which are deposited at lower RF power produce more leakage current, meanwhile the dielectric constant and refractive index of these films decreased mainly due to the more porosity in the film structure. By adding CF4 in the deposition process, fluorine, the most electronegative and the least polarized atom, doped into the silica film and led to decrease in the refractive index and the dielectric constant. In addition, no breakdown field was observed in the electrical characteristics of SiOxCyFz films and the leakage current of these films reduced by increment of the CF4 flow.

  17. The Tribological Behaviors of Three Films Coated on Biomedical Titanium Alloy by Chemical Vapor Deposition

    Science.gov (United States)

    Wang, Song; Liao, Zhenhua; Liu, Yuhong; Liu, Weiqiang

    2015-11-01

    Three thin films (DLC, a-C, and TiN) were performed on Ti6Al4V by chemical vapor deposition. Carbon ion implantation was pretreated for DLC and a-C films while Ti transition layer was pretreated for TiN film to strengthen the bonding strength. X-ray diffraction, Raman measurement, nano-hardness and nano-scratch tester, and cross-section etching by FIB method were used to analyze film characteristics. Tribological behaviors of these coatings were studied by articulation with both ZrO2 and UHMWPE balls using ball-on-disk sliding. The thickness values reached ~0.46, ~0.33, and ~1.67 μm for DLC, a-C, and TiN film, respectively. Nano-hardness of the coatings compared with that of untreated and bonding strength (critical load in nano-scratch test) values of composite coatings compared with that of monolayer film all increased significantly, respectively. Under destructive test (ZrO2 ball conterface) in bovine serum lubrication, TiN coating revealed the best wear resistance while DLC showed the worst. Film failure was mainly attributed to the plowing by hard ZrO2 ball characterized by abrasive and adhesive wear. Under normal test (UHMWPE ball conterface), all coatings showed significant improvement in wear resistance both in dry sliding and bovine serum lubrication. Both DLC and a-C films showed less surface damage than TiN film due to the self-lubricating phenomenon in dry sliding. TiN film showed the largest friction coefficient both in destructive and normal tests, devoting to the big TiN grains thus leading to much rougher surface and then a higher value. The self-lubricating film formed on DLC and a-C coating could also decrease their friction coefficients. The results indicated that three coatings revealed different wear mechanisms, and thick DLC or a-C film was more promising in application in lower stress conditions such as artificial cervical disk.

  18. 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

  19. Atomic-layer chemical-vapor-deposition of TiN thin films on Si(100) and Si(111)

    CERN Document Server

    Kim, Y S; Kim, Y D; Kim, W M

    2000-01-01

    An atomic-layer chemical vapor deposition (AL-CVD) system was used to deposit TiN thin films on Si(100) and Si(111) substrates by cyclic exposures of TiCl sub 4 and NH sub 3. The growth rate was measured by using the number of deposition cycles, and the physical properties were compared with those of TiN films grown by using conventional deposition methods. To investigate the growth mechanism, we suggest a growth model for TiN n order to calculate the growth rate per cycle with a Cerius program. The results of the calculation with the model were compared with the experimental values for the TiN film deposited using the AL-CVD method. The stoichiometry of the TiN film was examined by using Auger electron spectroscopy, and the chlorine and the oxygen impurities were examined. The x-ray diffraction and the transmission electron microscopy results for the TiN film exhibited a strong (200) peak and a randomly oriented columnar microstructure. The electrical resistivity was found to decrease with increasing deposit...

  20. Chemical vapor deposition of highly adherent diamond coatings onto co-cemented tungsten carbides irradiated by high power diode laser.

    Science.gov (United States)

    Barletta, M; Rubino, G; Valle, R; Polini, R

    2012-02-01

    The present investigation deals with the definition of a new eco-friendly alternative to pretreat Co-cemented tungsten carbide (WC-Co) substrates before diamond deposition by hot filament chemical vapor deposition (HFCVD). In particular, WC-5.8 wt %Co substrates were submitted to a thermal treatment by a continuous wave-high power diode laser to reduce surface Co concentration and promote the reconstruction of the WC grains. Laser pretreatments were performed both in N(2) and Ar atmosphere to prevent substrate oxidation. Diamond coatings were deposited onto the laser pretreated substrates by HFCVD. For comparative purpose, diamond coatings were also deposited on WC-5.8 wt %Co substrates chemically etched by the well-known two-step pretreatment employing Murakami's reagent and Caro's acid. Surface morphology, microstructure, and chemical composition of the WC-5.8 wt %Co substrates after the different pretreatments and the deposition of diamond coatings were assessed by surface profiler, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction analyses. Wear performance of the diamond coatings was checked by dry sliding linear reciprocating tribological tests. The worn volume of the diamond coatings deposited on the laser pretreated substrates was always found lower than the one measured on the chemically etched substrates, with the N(2) atmosphere being particularly promising.

  1. Synthesis of ZnO nanocrystals with novel hierarchical structures via atmosphere pressure physical vapor deposition method

    Science.gov (United States)

    Yan, Youguo; Zhang, Ye; Meng, Guowen; Zhang, Lide

    2006-09-01

    The search for hierarchically organized ZnO nanocrystals have been intense in recent years, due to both fundamental interest in nanocrystal growth subjects and their potential applications as components for building nanodetectors, optoelectronic, vacuum microelectronic, and spintronic nanodevices. We reported the first observation of a variety of novel nanostructures, such as nanocandle arrays, wine-bottle-shaped rod arrays, nanorivet arrays, periodic diamond-string and needle arrays, nanofern and needle arrays, tooth-shaped belt, spinal-shaped nanostructures and bamboo-shaped nanorod via an atmosphere pressure physical vapor deposition method. The unique feature of our method is atmosphere chamber pressure, which can induce chaos and fluctuation of source vapor and facilities multiply growth mechanisms to have competing dominating effects on the crystal growth of ZnO. The SEM and photoluminescence spectra confirm that those nanostructured ZnO crystals possess satisfactory structural and optical qualities.

  2. A Strategy to Design High-Density Nanoscale Devices utilizing Vapor Deposition of Metal Halide Perovskite Materials.

    Science.gov (United States)

    Hwang, Bohee; Lee, Jang-Sik

    2017-08-01

    The demand for high memory density has increased due to increasing needs of information storage, such as big data processing and the Internet of Things. Organic-inorganic perovskite materials that show nonvolatile resistive switching memory properties have potential applications as the resistive switching layer for next-generation memory devices, but, for practical applications, these materials should be utilized in high-density data-storage devices. Here, nanoscale memory devices are fabricated by sequential vapor deposition of organolead halide perovskite (OHP) CH 3 NH 3 PbI 3 layers on wafers perforated with 250 nm via-holes. These devices have bipolar resistive switching properties, and show low-voltage operation, fast switching speed (200 ns), good endurance, and data-retention time >10 5 s. Moreover, the use of sequential vapor deposition is extended to deposit CH 3 NH 3 PbI 3 as the memory element in a cross-point array structure. This method to fabricate high-density memory devices could be used for memory cells that occupy large areas, and to overcome the scaling limit of existing methods; it also presents a way to use OHPs to increase memory storage capacity. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. PENGARUH TEMPERATUR DEPOSISI PADA PENUMBUHAN FILM TIPIS SILIKON KARBIDA DENGAN METODE HOMEMADE HOT-MESH CHEMICAL VAPOR DEPOSITION

    Directory of Open Access Journals (Sweden)

    B Astuti

    2016-03-01

    Full Text Available Film tipis silikon karbida (SiC telah ditumbuhkan di atas substrate graphene/SiO2/Si dengan metode Homemade Hot-mesh chemical vapor deposition (Hot-Mesh CVD. Pengaruh dari temperature deposisi pada struktur dan morfologi film tipis SiC telah dipelajari dengan menggunakan X-Ray diffractometer (XRD, FESEM dan EDX, dan spektroskopi Raman. Karakterisasi XRD menunjukkan bahwa film tipis SiC memiliki struktur polikristal tipe kubik dengan orientasi (111. Kualitas film tipis SiC, dan ukuran butir kristal dari morfologi film yang dihasilkan meningkat dengan peningkatan temperatur deposisi. Dari karakterisasi spektroskopi Raman, dapati terdapat dua puncak pergeseran Raman yang dominan pada daerah sekitar 780 - 800 cm-1 dan  950 – 980 cm-1 yang merupakan mode fonon SiC-TO dan SiC-LO. Puncak pergeseran Raman tersebut bergeser ke bilangan gelombang yang lebih pendek dengan peningkatan temperature deposisi.Silicon carbide (SiC thin film grown on graphene/SiO2/Si substrate using homemade hot mesh chemical vapor deposition (Hot-Mesh SVD method has been done. Effect of  deposition temperature on structure and morphology of the thin film was studied by using X-ray diffractometer (XRD, FESEM and EDX, and Raman spectroscopy. XRD characteristics shows that SiC thin film has cubic polycrystalline structure with (111 orientation. Quality of the SiC thin film, and crystallite grain size from the film morphology was resulted increases with the increase of the deposition temperature. Based on the characterization of Raman spectroscopy, shows that two peak Raman shift in the range of 780 - 800 cm-1 and  950 – 980 cm-1 was attributed to SiC-TO and SiC-LO phonon mode.  The Raman shift peak was shifted toward the lower wavenumber with the increase of deposition temperature.

  4. Passivation of metal surface states: microscopic origin for uniform monolayer graphene by low temperature chemical vapor deposition.

    Science.gov (United States)

    Jeon, Insu; Yang, Heejun; Lee, Sung-Hoon; Heo, Jinseong; Seo, David H; Shin, Jaikwang; Chung, U-In; Kim, Zheong Gou; Chung, Hyun-Jong; Seo, Sunae

    2011-03-22

    Scanning tunneling microscopy (STM) and density functional theory (DFT) calculations were used to investigate the surface morphology and electronic structure of graphene synthesized on Cu by low temperature chemical vapor deposition (CVD). Periodic line patterns originating from the arrangements of carbon atoms on the Cu surface passivate the interaction between metal substrate and graphene, resulting in flawless inherent graphene band structure in pristine graphene/Cu. The effective elimination of metal surface states by the passivation is expected to contribute to the growth of monolayer graphene on Cu, which yields highly enhanced uniformity on the wafer scale, making progress toward the commercial application of graphene.

  5. High-Resolution Magnetic Force Microscopy Using Carbon Nanotube Probes Fabricated Directly by Microwave Plasma-Enhanced Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    Kei Tanaka

    2009-01-01

    Full Text Available Carbon nanotubes (CNTs have been successfully grown on the tip apex of an atomic force microscopy (AFM cantilever by microwave plasma-enhanced chemical vapor deposition (MPECVD. Both scanning electron microscopy (SEM and transmission electron microscopy (TEM observations reveal that the diameter of the CNTs is ∼30 nm and the magnetic particles with diameter of ∼20 nm, which was used as catalyst for the CNT growth, exist on the top. This CNT probe has been applied to magnetic force microscopy (MFM on the ultrahigh-density magnetic recording media with 1200 kilo flux change per inch (kfci.

  6. Oxygen source-oriented control of atmospheric pressure chemical vapor deposition of VO2 for capacitive applications

    Directory of Open Access Journals (Sweden)

    Dimitra Vernardou

    2016-06-01

    Full Text Available Vanadium dioxides of different crystalline orientation planes have successfully been fabricated by chemical vapor deposition at atmospheric pressure using propanol, ethanol and O2 gas as oxygen sources. The thick a-axis textured monoclinic vanadium dioxide obtained through propanol presented the best electrochemical response in terms of the highest specific discharge capacity of 459 mAh g-1 with a capacitance retention of 97 % after 1000 scans under constant specific current of 2 A g-1. Finally, the electrochemical impedance spectroscopy indicated that the charge transfer of Li+ through the vanadium dioxide / electrolyte interface was easier for this sample enhancing significantly its capacitance performance.

  7. Limiting Size of Monolayer Graphene Flakes Grown on Silicon Carbide or via Chemical Vapor Deposition on Different Substrates

    Science.gov (United States)

    Alekseev, N. I.

    2018-05-01

    The maximum size of homogeneous monolayer graphene flakes that form during the high-temperature evaporation of silicon from a surface of SiC or during graphene synthesis via chemical vapor deposition is estimated, based on the theoretical calculations developed in this work. Conditions conducive to the fragmentation of a monolayer graphene sheet to form discrete fragments or terrace-type structures in which excess energy due to dangling bonds at the edges is compensated for by the lack of internal stress are indentified and described. The results from calculations for the sizes of graphene structures are compared with experimental findings for the most successful graphene syntheses reported in the literature.

  8. Adsorption and desorption of P on (001) InP surface in metalorganic chemical vapor deposition by surface photoabsorption

    CERN Document Server

    Lee, T W; Moon, Y B; Yoon, E J; Kim, Y D

    1999-01-01

    We studied the surface structure of (001) InP in metalorganic chemical vapor deposition (MOCVD) ambient by surface photoabsorption (SPA). A P-dimer peak at 430 nm and an In-dimer peak at 600 nm were observed from the SPA subtraction spectra. A maximum SPA reflectivity change of 8 % between the P-stabilized and the In-stabilized surfaces was obtained at 470 nm. A first-order desorption kinetics was assumed to curve-fit the SPA signal and an activation energy of 3.36 eV was obtained.

  9. Physical and electrical properties of graphene grown under different hydrogen flow in low pressure chemical vapor deposition.

    Science.gov (United States)

    Hussain, Sajjad; Iqbal, Muhmmad Waqas; Park, Jaehyun; Ahmad, Muneer; Singh, Jai; Eom, Jonghwa; Jung, Jongwan

    2014-01-01

    Hydrogen flow during low pressure chemical vapor deposition had significant effect not only on the physical properties but also on the electrical properties of graphene. Nucleation and grain growth of graphene increased at higher hydrogen flows. And, more oxygen-related functional groups like amorphous and oxidized carbon that probably contributed to defects or contamination of graphene remained on the graphene surface at low H2 flow conditions. It is believed that at low hydrogen flow, those remained oxygen or other oxidizing impurities make the graphene films p-doped and result in decreasing the carrier mobility.

  10. Review on mechanism of directly fabricating wafer-scale graphene on dielectric substrates by chemical vapor deposition

    Science.gov (United States)

    Ning, Jing; Wang, Dong; Chai, Yang; Feng, Xin; Mu, Meishan; Guo, Lixin; Zhang, Jincheng; Hao, Yue

    2017-07-01

    To date, chemical vapor deposition on transition metal catalysts is a potential way to achieve low cost, high quality and uniform wafer-scale graphene. However, the removal and transfer process of the annoying catalytic metals underneath can bring large amounts of uncertain factors causing the performance deterioration of graphene, such as the pollution of surface polymeric residues, unmentioned doping and structural damages. Thus, to develop a technique of directly fabricating graphene on dielectric substrates is quite meaningful. In this review, we will present specific methods of catalyst- or transfer-free techniques for graphene growth and discuss the diversity of growth mechanisms.

  11. Method of plasma enhanced chemical vapor deposition of diamond using methanol-based solutions

    Science.gov (United States)

    Tzeng, Yonhua (Inventor)

    2009-01-01

    Briefly described, methods of forming diamond are described. A representative method, among others, includes: providing a substrate in a reaction chamber in a non-magnetic-field microwave plasma system; introducing, in the absence of a gas stream, a liquid precursor substantially free of water and containing methanol and at least one carbon and oxygen containing compound having a carbon to oxygen ratio greater than one, into an inlet of the reaction chamber; vaporizing the liquid precursor; and subjecting the vaporized precursor, in the absence of a carrier gas and in the absence in a reactive gas, to a plasma under conditions effective to disassociate the vaporized precursor and promote diamond growth on the substrate in a pressure range from about 70 to 130 Torr.

  12. Molecular dynamics simulation of chemical vapor deposition of amorphous carbon. Dependence on H/C ratio of source gas

    International Nuclear Information System (INIS)

    Ito, Atsushi M.; Takayama, Arimichi; Nakamura, Hiroaki; Saito, Seiki; Ohno, Noriyasu; Kajita, Shin

    2011-01-01

    By molecular dynamics simulation, the chemical vapor deposition of amorphous carbon onto graphite and diamond surfaces was studied. In particular, we investigated the effect of source H/C ratio, which is the ratio of the number of hydrogen atoms to the number of carbon atoms in a source gas, on the deposition process. In the present simulation, the following two source gas conditions were tested: one was that the source gas was injected as isolated carbon and hydrogen atoms, and the other was that the source gas was injected as hydrocarbon molecules. Under the former condition, we found that as the source H/C ratio increases, the deposition rate of carbon atoms decreases exponentially. This exponential decrease in the deposition rate with increasing source H/C ratio agrees with experimental data. However, under the latter molecular source condition, the deposition rate did not decrease exponentially because of a chemical reaction peculiar to the type of hydrocarbon in the source gas. (author)

  13. Vertically aligned Si nanocrystals embedded in amorphous Si matrix prepared by inductively coupled plasma chemical vapor deposition (ICP-CVD)

    Energy Technology Data Exchange (ETDEWEB)

    Nogay, G. [Department of Physics, Middle East Technical University (METU), Ankara 06800 (Turkey); Center of Solar Energy Research and Application (GÜNAM), Middle East Technical University (METU), Ankara 06800 (Turkey); Saleh, Z.M., E-mail: zaki.saleh@aauj.edu [Center of Solar Energy Research and Application (GÜNAM), Middle East Technical University (METU), Ankara 06800 (Turkey); Department of Physics, Arab American University–Jenin (AAUJ), Jenin, Palestine (Country Unknown); Özkol, E. [Center of Solar Energy Research and Application (GÜNAM), Middle East Technical University (METU), Ankara 06800 (Turkey); Department of Chemical Engineering, Middle East Technical University (METU), Ankara 06800 (Turkey); Turan, R. [Department of Physics, Middle East Technical University (METU), Ankara 06800 (Turkey); Center of Solar Energy Research and Application (GÜNAM), Middle East Technical University (METU), Ankara 06800 (Turkey)

    2015-06-15

    Highlights: • Inductively-coupled plasma is used for nanostructured silicon at room temperature. • Low temperature deposition allows device processing on various substrates. • Deposition pressure is the most effective parameter in controlling nanostructure. • Films consist of quantum dots in a-Si matrix and exhibit columnar vertical growth. • Films are porous to oxygen infusion along columnar grain boundaries. - Abstract: Vertically-aligned nanostructured silicon films are deposited at room temperature on p-type silicon wafers and glass substrates by inductively-coupled, plasma-enhanced chemical vapor deposition (ICPCVD). The nanocrystalline phase is achieved by reducing pressure and increasing RF power. The crystalline volume fraction (X{sub c}) and the size of the nanocrystals increase with decreasing pressure at constant power. Columnar growth of nc-Si:H films is observed by high resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM). The films exhibit cauliflower-like structures with high porosity that leads to slow but uniform oxidation after exposure to air at room temperature. Films deposited at low pressures exhibit photoluminescence (PL) signals that may be deconvoluted into three distinct Gaussian components: 760–810, 920–935, and 990–1000 nm attributable to the quantum confinement and interface defect states. Hydrogen dilution is manifested in significant enhancement of the PL, but it has little effect on the nanocrystal size and X{sub c}.

  14. Plasma vapor deposited n-indium tin oxide/p-copper indium oxide heterojunctions for optoelectronic device applications

    Science.gov (United States)

    Jaya, T. P.; Pradyumnan, P. P.

    2017-12-01

    Transparent crystalline n-indium tin oxide/p-copper indium oxide diode structures were fabricated on quartz substrates by plasma vapor deposition using radio frequency (RF) magnetron sputtering. The p-n heterojunction diodes were highly transparent in the visible region and exhibited rectifying current-voltage (I-V) characteristics with a good ideality factor. The sputter power during fabrication of the p-layer was found to have a profound effect on I-V characteristics, and the diode with the p-type layer deposited at a maximum power of 200 W exhibited the highest value of the diode ideality factor (η value) of 2.162, which suggests its potential use in optoelectronic applications. The ratio of forward current to reverse current exceeded 80 within the range of applied voltages of -1.5 to +1.5 V in all cases. The diode structure possessed an optical transmission of 60-70% in the visible region.

  15. Plasma-enhanced chemical-vapor deposition of titanium aluminum carbonitride/amorphous-carbon nanocomposite thin films

    Science.gov (United States)

    Shieh, Jiann; Hon, Min Hsiung

    2002-01-01

    A new nanocomposite, titanium aluminum carbonitride/amorphous-carbon thin film was prepared by radio-frequency (rf) plasma-enhanced chemical-vapor deposition using titanium tetrachloride, aluminum trichloride, methane, and nitrogen as reactants. Hydrogen was used as carrier gases. A substrate temperature of 500 °C and an rf power of 100 W were used in all depositions. The films were characterized by x-ray powder diffraction, Raman spectroscopy, x-ray photoelectron spectroscopy, transmission electron microscopy, and scanning electron microscopy. The results show that nanograins of titanium aluminum carbonitride were embedded in an amorphous-carbon matrix. The nanograins had a (200) preferred orientation with columnar cross-section morphology. Mechanical properties were analyzed by nanoindentation and hardness was demonstrated to increase via this microstructure design approach. The effects of microstructure on mechanical properties were also determined.

  16. Plasma-enhanced chemical-vapor deposition of titanium aluminum carbonitride/amorphous-carbon nanocomposite thin films

    International Nuclear Information System (INIS)

    Shieh Jiann; Hon, M.H.

    2002-01-01

    A new nanocomposite, titanium aluminum carbonitride/amorphous-carbon thin film was prepared by radio-frequency (rf) plasma-enhanced chemical-vapor deposition using titanium tetrachloride, aluminum trichloride, methane, and nitrogen as reactants. Hydrogen was used as carrier gases. A substrate temperature of 500 deg. C and an rf power of 100 W were used in all depositions. The films were characterized by x-ray powder diffraction, Raman spectroscopy, x-ray photoelectron spectroscopy, transmission electron microscopy, and scanning electron microscopy. The results show that nanograins of titanium aluminum carbonitride were embedded in an amorphous-carbon matrix. The nanograins had a (200) preferred orientation with columnar cross-section morphology. Mechanical properties were analyzed by nanoindentation and hardness was demonstrated to increase via this microstructure design approach. The effects of microstructure on mechanical properties were also determined

  17. Oxidizer partial pressure window for YBa2Cu3O(7-x) thin film formation by metalorganic chemical vapor deposition

    Science.gov (United States)

    Chern, C. S.; Zhao, J.; Norris, P. E.; Garrison, S. M.; Yau, K.; Li, Y. Q.; Gallois, B. M.; Kear, B. H.

    1992-10-01

    We conducted a systematic study of oxidizer partial pressure effects on both the superconducting transport properties and structural properties of YBa2Cu3O(7-x) (YBCO) films grown by conventional metalorganic chemical vapor deposition (MOCVD). Superconducting YBCO thin films were grown in partial N2O pressures ranging from 0.4 to 45 Torr and at substrate temperatures of 500 and 700 C. We observed a window in oxidizer partial pressure within which YBCO thin films can be formed in the as-deposited state by the MOCVD process. A trend of increasing b-axis orientation as the oxidizer partial pressure increased was revealed by detailed X-ray diffraction. The reduction of superconducting properties for films grown at high oxidizer partial pressure might result from the lack of surface mobility.

  18. Atmospheric-pressure epitaxial growth technique of a multiple quantum well by mist chemical vapor deposition based on Leidenfrost droplets

    Science.gov (United States)

    Kawaharamura, Toshiyuki; Dang, Giang T.; Nitta, Noriko

    2016-10-01

    A multiple quantum well α-Fe2O3/α-Ga2O3 with parallel and coherent formation of uniform and highly single-crystalline layers on a sapphire substrate has been fabricated by open-air atmospheric-pressure solution-processed mist chemical vapor deposition (Mist CVD). This report demonstrates that complicated structures with atomic-level control can be fabricated even in non-vacuum conditions by the Mist CVD. This can be achieved via the precise control of the precursor flow and ambient temperature combined with the formation of mist droplets of the special Leidenfrost state, which increased the atomic migration length by 108 times more than that of traditional vacuum techniques. This work could be a milestone in the transformation from vacuum to non-vacuum thin film deposition techniques towards a green and sustainable industry.

  19. Nanoscale leakage current measurements in metal organic chemical vapor deposition crystalline SrTiO3 films

    International Nuclear Information System (INIS)

    Rozier, Y.; Gautier, B.; Hyvert, G.; Descamps, A.; Plossu, C.; Dubourdieu, C.; Ducroquet, F.

    2009-01-01

    The properties of SrTiO 3 thin films, grown by liquid injection metal organic chemical vapor deposition on Si/SiO 2 , using a mixture of precursors, have been investigated at the nanoscale using an Atomic Force Microscope in the so-called Conductive Atomic Force Microscopy mode. Maps of the leakage currents with a nanometric resolution have been obtained on films elaborated at different temperatures and stoichiometries in order to discriminate the role of each parameter on the onset of leakage currents in the resulting layers. It appears that the higher the deposition temperature, the higher the leakage currents of the films. The mapping with a nanometric precision allows to show a heterogeneous behaviour of the surface with leaky grains and insulating boundaries. The study of films elaborated at the same temperature with different compositions supports the assumption that the leakage currents on Ti-rich layers are far higher than on Sr-rich layers

  20. Nanoscale leakage current measurements in metal organic chemical vapor deposition crystalline SrTiO{sub 3} films

    Energy Technology Data Exchange (ETDEWEB)

    Rozier, Y. [Lyon Institute of Nanotechnology (INL), CNRS-UMR5270, INSA Lyon, 7 avenue Capelle, 69621 VILLEURBANNE Cedex (France); Gautier, B. [Lyon Institute of Nanotechnology (INL), CNRS-UMR5270, INSA Lyon, 7 avenue Capelle, 69621 VILLEURBANNE Cedex (France)], E-mail: bgautier@insa-lyon.fr; Hyvert, G.; Descamps, A.; Plossu, C. [Lyon Institute of Nanotechnology (INL), CNRS-UMR5270, INSA Lyon, 7 avenue Capelle, 69621 VILLEURBANNE Cedex (France); Dubourdieu, C. [Laboratoire des Materiaux et du Genie Physique (LMGP), CNRS, INPG, 3 parvis L. Neel, BP 257, 38016 Grenoble Cedex 1 (France); Ducroquet, F. [Institut de Microelectronique, Electromagnetisme et Photonique (IMEP), 3, rue Parvis Louis Neel BP 257, 38016 GRENOBLE Cedex 1 (France)

    2009-01-30

    The properties of SrTiO{sub 3} thin films, grown by liquid injection metal organic chemical vapor deposition on Si/SiO{sub 2}, using a mixture of precursors, have been investigated at the nanoscale using an Atomic Force Microscope in the so-called Conductive Atomic Force Microscopy mode. Maps of the leakage currents with a nanometric resolution have been obtained on films elaborated at different temperatures and stoichiometries in order to discriminate the role of each parameter on the onset of leakage currents in the resulting layers. It appears that the higher the deposition temperature, the higher the leakage currents of the films. The mapping with a nanometric precision allows to show a heterogeneous behaviour of the surface with leaky grains and insulating boundaries. The study of films elaborated at the same temperature with different compositions supports the assumption that the leakage currents on Ti-rich layers are far higher than on Sr-rich layers.

  1. Preparation of titanium dioxide photocatalyst loaded onto activated carbon support using chemical vapor deposition: A review paper

    International Nuclear Information System (INIS)

    Li Puma, Gianluca; Bono, Awang; Krishnaiah, Duduku; Collin, Joseph G.

    2008-01-01

    Various methods to prepare and characterize TiO 2 photocatalyst loaded onto activated carbon (AC) support have been developed over the last decade. This photocatalyst has been used in a variety of investigations, i.e. from water decontamination to direct pollutant degradation in aqueous and gas phase systems using UV irradiation and lately with the assistance of ultrasonic sound waves. Chemical vapor deposition (CVD) method is one of the most promising and well-researched methods for deposition of catalysts onto supports. Given its advantage, from an engineering and fundamental aspect, CVD method also has commercial applications. A detailed search of published reports of these investigations was carried out and analyzed in this paper with focus on CVD techniques, activated carbon support and sonication

  2. Nanostructure and optical properties of CeO{sub 2} thin films obtained by plasma-enhanced chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Barreca, D.; Bruno, G.; Gasparotto, A.; Losurdo, M.; Tondello, E

    2003-12-15

    In the present study, Spectroscopic Ellipsometry (SE) is used to investigate the interrelations between nanostructure and optical properties of CeO{sub 2} thin films deposited by Plasma-Enhanced Chemical Vapor Deposition (PE-CVD). The layers were synthesized in Ar and Ar-O{sub 2} plasmas on Si(100) substrates at temperatures lower than 300 deg. C. Both the real and imaginary parts of the complex dielectric functions and, subsequently, the optical constants of the films are derived up to 6.0 eV photon energy. Particular attention is devoted to the influence of synthesis conditions and sample properties on the optical response, taking into account the effects of surface roughness and SiO{sub 2} interface layer on Si.

  3. Aerosol - assisted Chemical Vapor Deposition of Metal Oxide Structures: Zinc Oxide Rods

    Czech Academy of Sciences Publication Activity Database

    Vallejos, S.; Pizúrová, Naděžda; Čechal, J.; Grácia, I.; Cané, C.

    2017-01-01

    Roč. 2017, Č. 127 (2017), č. článku e56127. ISSN 1940-087X Institutional support: RVO:68081723 Keywords : Zinc oxide * columnar structures * rods * AACVD * non-catalyzed growth * vapor-solid mechanism Subject RIV: CA - Inorganic Chemistry OBOR OECD: Polymer science Impact factor: 1.232, year: 2016 https://www.jove.com/video/56127

  4. Vapor deposition of polystyrene thin films by intense laser vibrational excitation

    DEFF Research Database (Denmark)

    Bubb, D.M.; Papantonakis, M.R.; Horwitz, J.S.

    2002-01-01

    Polystyrene films were deposited using resonant infrared pulsed laser depositions (RIR-PLD). Thin films were grown on Si(1 1 1) wafers and NaCl substrates and analyzed by Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). The depositions were carried out...... in vacuum (10(-4)-10(-5) Torr) at wavelengths 3.28, 3.30, 3.42 and 3.48 mum which are resonant with CH2 stretching modes in the polymer. We also attempted to deposit a films using non-resonant infrared (RIR) excitation (2.90 mum). At this wavelength no films were deposited, and evidence for laser......-induced damage to the target can be seen. RIR-PLD is a fundamentally new approach to polymer thin film growth as the absorption of radiation resonant with vibrational modes allow the energy to be deposited into the polymer and transfers between macromolecules in such a way as to promote efficient, non...

  5. Plasma and process characterization of high power magnetron physical vapor deposition with integrated plasma equipment--feature profile model

    International Nuclear Information System (INIS)

    Zhang Da; Stout, Phillip J.; Ventzek, Peter L.G.

    2003-01-01

    High power magnetron physical vapor deposition (HPM-PVD) has recently emerged for metal deposition into deep submicron features in state of the art integrated circuit fabrication. However, the plasma characteristics and process mechanism are not well known. An integrated plasma equipment-feature profile modeling infrastructure has therefore been developed for HPM-PVD deposition, and it has been applied to simulating copper seed deposition with an Ar background gas for damascene metalization. The equipment scale model is based on the hybrid plasma equipment model [M. Grapperhaus et al., J. Appl. Phys. 83, 35 (1998); J. Lu and M. J. Kushner, ibid., 89, 878 (2001)], which couples a three-dimensional Monte Carlo sputtering module within a two-dimensional fluid model. The plasma kinetics of thermalized, athermal, and ionized metals and the contributions of these species in feature deposition are resolved. A Monte Carlo technique is used to derive the angular distribution of athermal metals. Simulations show that in typical HPM-PVD processing, Ar + is the dominant ionized species driving sputtering. Athermal metal neutrals are the dominant deposition precursors due to the operation at high target power and low pressure. The angular distribution of athermals is off axis and more focused than thermal neutrals. The athermal characteristics favor sufficient and uniform deposition on the sidewall of the feature, which is the critical area in small feature filling. In addition, athermals lead to a thick bottom coverage. An appreciable fraction (∼10%) of the metals incident to the wafer are ionized. The ionized metals also contribute to bottom deposition in the absence of sputtering. We have studied the impact of process and equipment parameters on HPM-PVD. Simulations show that target power impacts both plasma ionization and target sputtering. The Ar + ion density increases nearly linearly with target power, different from the behavior of typical ionized PVD processing. The

  6. Synthesis of multi-walled carbon nanotubes by combining hot-wire and dc plasma-enhanced chemical vapor deposition

    International Nuclear Information System (INIS)

    Sorin Cojocaru, Costel; Kim, Dohyung; Pribat, Didier; Bouree, Jean-Eric

    2006-01-01

    Multi-walled carbon nanotubes (MWCNTs) have been grown on 7 nm Ni-coated substrates consisting of crystalline silicon covered with a thin layer (10 nm) of TiN, by combining hot-wire chemical vapor deposition (HWCVD) and direct current plasma-enhanced chemical vapor deposition (dc PECVD), at 620 deg. C. Acetylene (C 2 H 2 ) gas is used as the carbon source and ammonia (NH 3 ) and hydrogen (H 2 ) are used either for dilution or etching. The carbon nanotubes range from 20 to 100 nm in diameter and 0.3 to 5 μm in length, depending on growth conditions: plasma intensity, filament current, pressure, C 2 H 2 , NH 3 , H 2 flow rates, C 2 H 2 /NH 3 and C 2 H 2 /H 2 mass flow ratios. By combining the HWCVD and the dc PECVD processes, uniform growth of oriented MWCNTs was obtained, whereas by using only the HWCVD process, tangled MWCNTs were obtained. By patterning the nickel catalyst, with the use of the HW dc PECVD process, uniform arrays of nanotubes have been grown as well as single free-standing aligned nanotubes, depending on the catalyst patterning (optical lithography or electron-beam lithography). In the latter case, electron field emission from the MWCNTs was obtained with a maximum emission current density of 0.6 A/cm 2 for a field of 16 V/μm

  7. Single liquid source plasma enhanced metalorganic chemical vapor deposition of YBa2Cu3O(7-x) thin films

    Science.gov (United States)

    Zhang, Jiming; Gardiner, Robin; Kirlin, Peter S.; Boerstler, Robert W.; Steinbeck, John

    1992-07-01

    High quality YBa2Cu3O(7-x) films were grown in-situ on LaAlO3 (100) by a novel single liquid source plasma-enhanced metalorganic chemical vapor deposition process. The metalorganic complexes M(thd)(sub n), (thd = 2,2,6,6-tetramethyl-3,5-heptanedionate; M = Y, Ba, Cu) were dissolved in an organic solution and injected into a vaporizer immediately upstream of the reactor inlet. The single liquid source technique dramatically simplifies current CVD processing and can significantly improve the process reproducibility. X-ray diffraction. measurements indicated that single phase, highly c-axis oriented YBa2Cu3O(7-x) was formed in-situ at a substrate temperature 680 C. The as-deposited films exhibited a mirror-like surface, had transition temperature T(sub c0) approximately equal to 89 K, Delta T(sub c) less than 1 K, and Jc (77 K) = 10(exp 6) A/sq cm.

  8. Plasma enhanced chemical vapor deposition of ZrO2 thin films

    Energy Technology Data Exchange (ETDEWEB)

    Saravanan, Kolandaivelu [Iowa State Univ., Ames, IA (United States)

    1993-12-09

    Amorphous ZrO2 thin films were deposited in an inductively coupled PECVD system using a Zr β-diketonate, Zr(C11H19O2)4, as the precursor. The deposits were air annealed at 900C for 5 min to get pure, single phase, oriented, polycrystalline α-ZrO2. Feasibility of using 2 different types of reactors was investigated. The inductively heated horizontal reactor depositions at 600C had a lower deposition rate and the films were non-uniform in thickness with a columnar structure. The resistively heated vertical reactor depositions at 350C had a higher deposition rate and the films were more uniform in thickness with a fine grained microstructure. The statistical design was demonstrated as an effective technique to analyze the effect of process conditions on the rate of deposition and relative (h00) orientation. The factorial design was used to quantify the two responses in terms of the process variables and their mutual interactions. The statistical design for rate of deposition was found to correlate with the trends observed in classical design.

  9. Linking the operating parameters of chemical vapor deposition reactors with film conformality and surface nano-morphology.

    Science.gov (United States)

    Cheimarios, Nikolaos; Garnelis, Sokratis; Kokkoris, George; Boudouvis, Andreas G

    2011-09-01

    A multiscale modeling framework is used to couple the co-existing scales, i.e., macro-, micro- and nano-scale, in chemical vapor deposition (CVD) processes. The framework consists of a reactor scale model (RSM) for the description of the transport phenomena in the bulk phase (macro-scale) of a CVD reactor and two models for the micro- and nano-scale: (a) A feature scale model (FSM) describing the deposition of a film inside features on a predefined micro-topography on the wafer and (b) a nano-morphology model (NMM) describing the surface morphology evolution during thin film deposition on an initially flat surface. The FSM is deterministic and consists of three sub-models: A ballistic model for the species' transport inside features, a surface chemistry model, and a profile evolution algorithm based on the level set method. The NMM is stochastic and is based on the kinetic Monte Carlo method. The coupling of RSM with FSM is performed through a correction of the species consumption on the wafer. The linking of RSM with NMM is performed through "feeding" of the deposition rate calculated by RSM to the NMM. The case study is CVD of Silicon (Si) from Silane. The effect of the reactor's operating parameters on the Si film conformality inside trenches is investigated by the coupling of RSM with FSM. The formation of dimmers on an initially flat Si (001) surface as well as the periodic change of the surface nano-morphology is predicted.

  10. Chemical vapor deposition of silica, alumina, and aluminosilicates from mixtures of aluminum trichloride, chlorosilane, carbon dioxide, and hydrogen

    Science.gov (United States)

    Nitodas, Stephanos F.

    The objective of this study is the comprehensive investigation of the kinetics of the codeposition of silica (SiO2), alumina (Al 2O3), mullite (3Al2O3·2SiO 2), and other aluminosilicates from mixtures of chlorosilane (SiCl 4 or MTS), aluminum trichloride, carbon dioxide, and hydrogen in order to prepare coatings for the protection of SiC-based ceramics from oxidation in high-temperature applications. In an attempt to elucidate some aspects of the codeposition process, the deposition of silica and alumina from chlorosilane and aluminum trichloride, respectively, in carbon dioxide and hydrogen is also studied. Experiments are conducted in a tubular, hot-wall chemical vapor deposition reactor, coupled to an electronic microbalance, using various substrates. The effects of process parameters on deposition rate, film morphology, and film composition are examined over a wide range of experimental conditions. Among the most interesting results of this study is that the presence of AlCl 3 has a catalytic effect on the incorporation of silica in the deposit, leading to codeposition rates that are higher than the deposition rates that are obtained when only one of the two chlorides (chlorosilane or AlCl 3 is present in the feed. The results of the deposition experiments also show that manipulation of the temperature of the reaction and the residence time of the mixture in the reactor offers a way to control the composition of the codeposited films in SiO2 and Al2O3, obtaining deposits with significant alumina and aluminosilicate (e.g., mullite) content. In order to account for the complex chemistry of the formation of the oxide films, detailed homogeneous and heterogeneous mechanisms are developed for the deposition of silica, the deposition of alumina, and the codeposition process. The kinetic mechanisms encompass several reaction sequences for the generation of deposition precursors and the formation of solid phases, and are incorporated into the reaction and transport

  11. A chemical and fluid dynamic study of the chemical vapor deposition of aluminum nitride in a vertical reactor

    Science.gov (United States)

    Bather, Wayne Anthony

    The metalorganic chemical vapor deposition (MOCVD) growth of compound semiconductors has become important in producing many high performance electronic and optoelectronic devices from the wide bandgaps III-V nitrides, for example, aluminum nitride (AlN). A systematic theoretical and experimental investigation of the chemistry and mass transport process in a MOCVD system can yield predictive models of the deposition process. The chemistries and fluid dynamics of the MOCVD growth of AlN in a vertical reactor is analyzed and characterized in order to parameterize and model the deposition process. A Fourier Transform Infrared (FTIR) spectroscopic study of the predeposition reactions between trimethylaluminum (TMAl) and ammonia (NHsb3) is carried out in a static gas cell to examine the primary homogeneous gas phase reactions, pyrolysis of the reactants, and adduct formation, possibly accompanied by elimination reactions. A series of reactions, based on laboratory studies and literature review, is then proposed to model the deposition process. All pertinent kinetic, thermochemical, and transport properties were obtained. Utilizing a mass transport model, we performed computational fluid dynamics calculations using the FLUENT software package. We determined temperature, velocity, and concentration profiles, along with deposition rates inside the experimental vertical CVD reactor in the Howard University Material Science Research Center of Excellence. Experimental deposition rate data were found to be in good agreement with those predicted from the simulations, thus validating the proposed model. The control of the homogeneous gas phase reaction leading to the formation and subsequent decomposition of the adduct is critical to the formation of device-grade AlN films. Many basic processes occurring during MOCVD of AlN are still not completely understood, and none of the detailed surface reaction mechanisms are known.

  12. 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.

  13. Fabrication of single-phase ε-GaSe films on Si(100) substrate by metal organic chemical vapor deposition

    International Nuclear Information System (INIS)

    Chang, Chia-Chen; Zeng, Jia-Xian; Lan, Shan-Ming; Uen, Wu-Yih; Liao, Sen-Mao; Yang, Tsun-Neng; Ma, Wei-Yang; Chang, Kuo-Jen

    2013-01-01

    Single-phase ε-gallium selenide (GaSe) films were fabricated on Si(100) substrate by metal organic chemical vapor deposition using dual-source precursors: triethylgallium (TEG) and hydrogen selenide (H 2 Se) with the flow ratio of [H 2 Se]/[TEG] being maintained at 1.2. In particular, an arsine (AsH 3 ) flow was introduced to the Si substrate before the film deposition to induce an arsenic (As)-passivation effect on the substrate. The crystalline structure of GaSe films prepared was analyzed using X-ray diffraction and the surface morphology of them was characterized by scanning electron microscopy. It was found that the film quality could be improved by the As-passivation effect. The optical properties of the films were studied by temperature dependent photoluminescence (PL) measurements. PL spectra obtained with different distributions and intensities favored for resolving the superior material quality of the films produced on the substrate with As-passivation compared to those produced on the substrate without As-passivation. The former was dominated by the excitonic emissions for the whole temperature range of 20–300 K examined, while the latter was initially dominated by the defect-related emission at 1.907 eV for a low-temperature range ≦ 80 K and then became dominated by the weak excitonic emission band instead. The ε modification of GaSe films prepared was further recognized by the Raman scattering measurements conducted at room temperature. - Highlights: • Gallium selenide (GaSe) layered structures are fabricated on Si(100) substrate. • Metal–organic chemical vapor deposition is used for film fabrication. • Arsenic-passivation effects of Si substrate on the GaSe film quality are analyzed. • Photoluminescence measurements of GaSe polycrystals are reported

  14. The impact of hydrogen and oxidizing impurities in chemical vapor deposition of graphene on copper

    Science.gov (United States)

    Choubak, Saman

    Graphene, the single-atom layer of carbon, has attracted scientists and technologists due to its outstanding physical and opto/electronic properties. The use of graphene in practical applications requires a reliable and cost-effective method to produce large area graphene films with low defects and controlled thicknesses. Direct growth of graphene using chemical vapor deposition (CVD) on copper, in which carbonaceous gaseous species react with the metal substrate in the presence of hydrogen at high temperatures (850-1100° C), led to high coverage of high quality graphene, opening up a promising future for methods of this type and a large step towards commercial realization of graphene products. The present thesis deals with the synthesis of graphene via low pressure CVD (LP-CVD) on copper catalyst using methane as the carbon precursor. The focus is mainly on the determination of the role of hydrogen and oxidizing impurities during graphene formation with an ultimate purpose: to elucidate a viable and reproducible method for the production of high quality graphene films compatible with industrial manufacturing processes. The role of molecular hydrogen in graphene CVD is explored in the first part of the thesis. Few studies claimed that molecular hydrogen etches graphene films on copper by conducting annealing experiments. On the other hand, we speculated that this graphene etching reaction is due to the presence of trace amount of oxygen in the furnace atmosphere. Thus, we took another approach and designed systematic annealing experiments to investigate the role of hydrogen in the etching reaction of graphene on copper foils. No evidence of graphene etching on copper was observed when purified ultra high purity (UHP) hydrogen was used at 825 °C and 500 mTorr. Nevertheless, graphene films exposed to the unpurified UHP hydrogen were etched due to the presence of oxidizing impurities. Our results show that hydrogen is not responsible for graphene etching reaction

  15. Long-term stable water vapor permeation barrier properties of SiN/SiCN/SiN nanolaminated multilayers grown by plasma-enhanced chemical vapor deposition at extremely low pressures

    International Nuclear Information System (INIS)

    Choi, Bum Ho; Lee, Jong Ho

    2014-01-01

    We investigated the water vapor permeation barrier properties of 30-nm-thick SiN/SiCN/SiN nanolaminated multilayer structures grown by plasma enhanced chemical vapor deposition at 7 mTorr. The derived water vapor transmission rate was 1.12 × 10 −6 g/(m 2 day) at 85 °C and 85% relative humidity, and this value was maintained up to 15 000 h of aging time. The X-ray diffraction patterns revealed that the nanolaminated film was composed of an amorphous phase. A mixed phase was observed upon performing high resolution transmission electron microscope analysis, which indicated that a thermodynamically stable structure was formed. It was revealed amorphous SiN/SiCN/SiN multilayer structures that are free from intermixed interface defects effectively block water vapor permeation into active layer

  16. Synthesis of carbon nanomaterials by catalytic chemical vapor deposition: growth mechanisms on metal powders and foils

    OpenAIRE

    Romero Rodríguez, Pablo

    2017-01-01

    Actualmente, las excelentes propiedades proporcionadas a escala nanométrica por los nanomateriales de carbono, como nanotubos y grafeno, motivan la propuesta teórica de un gran número de aplicaciones. Estos nanomateriales se pueden producir por deposición química en fase vapor (CVD), que consiste en la descomposición térmica de hidrocarburos sobre catalizadores metálicos. La técnica de CVD permite, a través del control de las condiciones de síntesis y la composición y morfología del catalizad...

  17. Self-catalytic growth of tin oxide nanowires by chemical vapor deposition process

    CSIR Research Space (South Africa)

    Thabethe, BS

    2013-01-01

    Full Text Available are commercially available for detecting fuel gas, carbon monoxide, combustible gases, ammonia, water vapour, and numerous other gases and vapors [11]. Due to the enhanced surface-to-volume ratio of 1D struc- tures, tin oxide nanowires have been shown to have... power consumption [15]. It has been reported by several authors that the performances of gas sensors can be enhanced by increasing the specific surface area by way of achieving nanoparticles [16, 17] and by incorporation of noble metals [18...

  18. In-situ epitaxial growth of heavily phosphorus doped SiGe by low pressure chemical vapor deposition

    CERN Document Server

    Lee, C J

    1998-01-01

    We have studied epitaxial crystal growth of Si sub 1 sub - sub x Ge sub x films on silicon substrates at 550 .deg. C by low pressure chemical vapor deposition. In a low PH sub 3 partial pressure region such as below 1.25x10 sup - sup 3 Pa, both the phosphorus and carrier concentrations increased with increasing PH sub 3 partial pressure, but the deposition rate and the Ge fraction remained constant. In a higher PH sub 3 partial pressure region, the deposition rate, the phosphorus concentration, and the carrier concentration decreased, while the Ge fraction increased. These suggest that high surface coverage of phosphorus suppresses both SiH sub 4 and GeH sub 4 adsorption/reactions on the surfaces, and its suppression effect on SiH sub 4 is actually much stronger than on GeH sub 4. In particular, epitaxial crystal growth is largely controlled by surface coverage effect of phosphorus in a higher PH sub 3 partial pressure region.

  19. Photocatalytic reaction characteristics of the titanium dioxide supported on the long phosphorescent phosphor by a low pressure chemical vapor deposition.

    Science.gov (United States)

    Kim, Jung-Sik; Kim, Seung-Woo; Jung, Sang-Chul

    2014-10-01

    This study investigated the photocatalytic behavior of titanium dioxide (TiO2)-supported on the long phosphorescent materials. Nanocrystalline TiO2 was directly deposited on the plate of alkaline earth aluminate phosphor, CaAl2O4: Eu2+, Nd3+ by a low pressure chemical vapor deposition (LPCVD). Photocatalytic reaction performance was examined with the decomposition of benzene gas by using a gas chromatography (GC) system under ultraviolet and visible light (λ > 410 nm) irradiations. The LPCVD TiO2-coated phosphors showed active photocatalytic reaction under visible irradiation. The mechanism of the photocatalytic reactivity for the TiO,-coated phosphorescent phosphor was discussed in terms of the energy band structure and phosphorescence. The coupling of TiO2 with phosphor may result in energy band bending in the junction region, which makes the TiO, crystal at the interface to be photo-reactive under visible light irradiation. The fastest degradation of ben- zene gas occurred for the TiO,-coated phosphor prepared with 1 min deposition time (-150 nm thickness). The LPCVD TiO,-coated phosphor is also photo-reactive under darkness through the light photons emitted from the CaAl2O4 phosphor. In addition, the TiO2-coated phosphorescent phosphors were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM).

  20. P-channel transparent thin-film transistor using physical-vapor-deposited NiO layer

    Science.gov (United States)

    Lin, Chiung-Wei; Chung, Wei-Chieh; Zhang, Zhao-De; Hsu, Ming-Chih

    2018-01-01

    The effect of oxygen (O) content on the electrical properties of physical-vapor-deposited nickel oxide (PVD-NiO) was studied. When the NiO target was sputtered, introducing O2 can lead to the formation of Ni3+ ions in the deposited film. These Ni3+ ions can act as acceptors. However, there were too many Ni3+ ions that were obtained following the introduction of O atoms. It resulted in intensive p-type conduction and made the O2-introduced PVD-NiO behave as a conductor. Thus, it was possible to reduce the O content of PVD-NiO to obtain a p-type semiconductor. In this study, a transparent PVD-NiO film with a carrier concentration of 1.62 × 1017 cm-3 and a resistivity of 3.74 Ω cm was sputter-deposited within pure argon plasma. The thin-film transistor (TFT) employing this proposed PVD-NiO can result in good current switching, and even operated at very low drain-source voltage. The ON/OFF current ratio, field-effect carrier mobility, and threshold voltage of the proposed NiO TFT were 3.61 × 104, 1.09 cm2 V-1 s-1 and -3.31 V, respectively.

  1. Plasma-enhanced chemical vapor deposition of ortho-carborane: structural insights and interaction with Cu overlayers.

    Science.gov (United States)

    James, Robinson; Pasquale, Frank L; Kelber, Jeffry A

    2013-09-04

    X-ray and ultraviolet photoelectron spectroscopy (XPS, UPS) are used to investigate the chemical and electronic structure of boron carbide films deposited from ortho-carborane precursors using plasma-enhanced chemical vapor deposition (PECVD), and the reactivity of PECVD films toward sputter-deposited Cu overlayers. The XPS data provide clear evidence of enhanced ortho-carborane reactivity with the substrate, and of extra-icosahedral boron and carbon species; these results differ from results for films formed by condensation and electron beam induced cross-linking of ortho-carborane (EBIC films). The UPS data show that the valence band maximum for PECVD films is ∼1.5 eV closer to the Fermi level than for EBIC films. The XPS data also indicate that PECVD films are resistant to thermally-stimulated diffusion of Cu at temperatures up to 1000 K in UHV, in direct contrast to recently reported results, but important for applications in neutron detection and in microelectronics.

  2. Thermodynamic calculations for chemical vapor deposition of silicon carbide using ethyltrichlorosilane

    International Nuclear Information System (INIS)

    Nakano, Junichi; Yamada, Reiji

    1995-06-01

    The computer code SOLGASMIX-PV, which is based on the free energy minimization method, was used to calculate the equilibrium composition of the C 2 H 5 SiCl 3 -H 2 -Ar system. In the C 2 H 5 SiCl 3 -H 2 system, the calculation results showed that β-SiC+C, β-SiC, β-SiC+Si(1), Si(1), β-SiC+Si(s), and Si(s) would be deposited, whereas β-SiC+C and C would be deposited in the C 2 H 5 SiCl 3 -Ar system. By comparing the calculated results with the experimental results from the literature, in the region calculated as β-SiC+C to be deposited, β-SiC+C, β-SiC, or β-SiC+Si(s) was deposited in the experiments. The calculations revealed that the gas mole ratios for CVD were optimum when the (Ar+H 2 )/C 2 H 5 SiCl 3 took a value between 1000 and 10000, and the Ar/H 2 between 0.43 and 1.5. The deposition temperature was optimum between 1100-1500K. In this region, the Si atoms were most effectively used as source materials, and formed a single phase of β-SiC on the substrate. (author)

  3. Post deposition annealing temperature effect on silicon quantum dots embedded in silicon nitride dielectric multilayer prepared by hot-wire chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Panchal, A.K., E-mail: ashishpanchal@me.iitb.ac.i [Department of Energy Science and Engineering, IIT Bombay, Powai, Mumbai 400 076 (India); Solanki, C.S. [Department of Energy Science and Engineering, IIT Bombay, Powai, Mumbai 400 076 (India)

    2009-04-30

    The preparations of the 20-period of a Si quantum dot (QD)/SiN{sub x} multilayer in a hot-wire chemical vapor deposition (HWCVD) chamber is presented in this paper. The changes in the properties of Si-QDs after the post deposition annealing treatment are studied in detail. Alternate a-Si:H and SiN{sub x} layers are grown in a single SiN{sub x} deposition chamber by cracking SiH{sub 4}, and SiH{sub 4} + NH{sub 3}, respectively at 250 {sup o}C. The as-deposited samples are annealed in the temperature range of 800 {sup o}C to 950 {sup o}C to grow Si-QDs. All the samples are characterized by confocal micro Raman, transmission electron microscope (TEM), and photoluminescence (PL) to study the changes in the film structures after the annealing treatment. The micro Raman analysis of the samples shows the frequency line shifting from 482 cm{sup -1} to 500 cm{sup -1} indicating the Si transition from an amorphous to a crystalline phase. The TEM micrograph inspection indicates the formation of Si-QDs of size 3 to 5 nm and a density of 5 x 10{sup 12}/cm{sup 2}. The high resolution TEM micrographs show an agglomeration of Si-QDs with an increase in the annealing temperature. The PL spectra show a peak shifting from 459 nm to 532 nm with increasing the annealing temperature of the film.

  4. An evaluation of absorption spectroscopy to monitor YBa2Cu3O7-x precursors for metal organics chemical vapor deposition processing

    International Nuclear Information System (INIS)

    Matthew Edward Thomas

    1999-01-01

    Absorption spectroscopy was evaluated as a technique to monitor the metal organics chemical vapor deposition (MOCVD) process for forming YBa 2 Cu 3 O 7-x superconducting coated conductors. Specifically, this study analyzed the feasibility of using absorption spectroscopy to monitor the MOCVD supply vapor concentrations of the organic ligand 2,2,6,6-tetramethyl-3,5-heptanedionate (TMHD) metal chelates of barium, copper, and yttrium. Ba(TMHD) 2 , Cu(TMHD) 2 , and Y(TMHD) 3 compounds have successfully been vaporized in the MOCVD processing technique to form high temperature superconducting ''coated conductors,'' a promising technology for wire fabrication. The absorption study of the barium, copper, and yttrium (TMHD) precursors was conducted in the ultraviolet wavelength region from 200nm to 400nm. To simulate the MOCVD precursor flows the Ba(TMHD) 2 , Cu(TMHD) 2 , and Y(TMHD) 3 complexes were vaporized at vacuum pressures of (0.03--10)Torr. Spectral absorption scans of each precursor were conducted to examine potential measurement wavelengths for determining vapor concentrations of each precursor via Beer's law. The experimental results show that under vacuum conditions the barium, copper, and yttrium (TMHD) precursors begin to vaporize between 90 C and 135 C, which are considerably lower vaporization temperatures than atmospheric thermal gravimetric analyses indicate. Additionally, complete vaporization of the copper and yttrium (TMHD) precursors occurred during rapid heating at temperatures between 145 C and 195 C and after heating at constant temperatures between 90 C and 125 C for approximately one hour, whereas the Ba(TMHD) 2 precursor did not completely vaporize. At constant temperatures, near constant vaporization levels for each precursor were observed for extended periods of time. Detailed spectroscopic scans at stable vaporization conditions were conducted

  5. Versatility of metalorganic chemical vapor deposition process for fabrication of high quality YBCO superconducting thin films

    Science.gov (United States)

    Chern, C. S.; Kear, B. H.; Zhao, J.; Norris, P. E.; Li, Y. Q.

    1991-03-01

    YBCO films, having critical current densities in excess of 10 to the 6th A/sq cm at 77 K and transition temperatures of about 89 K, successfully deposited on close lattice matched substrate materials at substrate temperature in the range from 720 to 740 C, are presented. The critical current densities are 10,000 A/sq cm at 70 K and the critical temperatures are 82 K for the films deposited on sapphire substrates. Successful deposition of c-axis oriented YBCO films with a transition temperature of 85 K was also achieved on silver substrates. Detailed analyses of the films were carried out by X-ray diffraction, EDS, SEM, resistivity measurements, critical current density measurements, and magnetization susceptibility measurements.

  6. Superconducting YBa2Cu3O7 - x thin films on silver substrates by in situ plasma-enhanced metalorganic chemical vapor deposition

    Science.gov (United States)

    Zhao, J.; Li, Y. Q.; Chern, C. S.; Norris, P.; Gallois, B.; Kear, B.; Wessels, B. W.

    1991-01-01

    An in situ microwave plasma-enhanced metalorganic chemical vapor deposition process was used to fabricate highly c-axis oriented YBa2Cu3O7-x superconducting thin films on metallic Ag substrates. The films were deposited at a reduced substrate temperature of 740 °C in about 270 Pa of N2O ambient. Magnetic susceptibilities versus temperature of the as-deposited films show attainment of zero resistance of 85 K and composition of single (high Tc) phase. X-ray diffraction measurements reveal that the films deposited at 740 °C have highly preferential orientation of the crystallite c axes perpendicular to the substrate surface.

  7. InAs/GaSb core-shell nanowires grown on Si substrates by metal-organic chemical vapor deposition

    Science.gov (United States)

    Ji, Xianghai; Yang, Xiaoguang; Du, Wenna; Pan, Huayong; Luo, Shuai; Ji, Haiming; Xu, Hongqi; Yang, Tao

    2017-06-01

    We report the growth of InAs/GaSb core-shell heterostructure nanowires with smooth sidewalls on Si substrates using metal-organic chemical vapor deposition (MOCVD) with no assistance from foreign catalysts. Sb adatoms were observed to strongly influence the morphology of the GaSb shell. In particular, Ga droplets form on the nanowire tips when a relatively low TMSb flow rate is used, whereas the droplets are missing and the radial growth of the GaSb is enhanced due to a reduction in the diffusion length of the Ga adatoms when the TMSb flow rate is increased. Moreover, transmission electron microscopy measurements revealed that the GaSb shell coherently grew on the InAs core without any misfit dislocations.

  8. Micro-light-emitting diodes with III–nitride tunnel junction contacts grown by metalorganic chemical vapor deposition

    Science.gov (United States)

    Hwang, David; Mughal, Asad J.; Wong, Matthew S.; Alhassan, Abdullah I.; Nakamura, Shuji; DenBaars, Steven P.

    2018-01-01

    Micro-light-emitting diodes (µLEDs) with tunnel junction (TJ) contacts were grown entirely by metalorganic chemical vapor deposition. A LED structure was grown, treated with UV ozone and hydrofluoric acid, and reloaded into the reactor for TJ regrowth. The silicon doping level of the n++-GaN TJ was varied to examine its effect on voltage. µLEDs from 2.5 × 10‑5 to 0.01 mm2 in area were processed, and the voltage penalty of the TJ for the smallest µLED at 20 A/cm2 was 0.60 V relative to that for a standard LED with indium tin oxide. The peak external quantum efficiency of the TJ LED was 34%.

  9. Metallic 1T phase source/drain electrodes for field effect transistors from chemical vapor deposited MoS2

    Directory of Open Access Journals (Sweden)

    Rajesh Kappera

    2014-09-01

    Full Text Available Two dimensional transition metal dichalcogenides (2D TMDs offer promise as opto-electronic materials due to their direct band gap and reasonably good mobility values. However, most metals form high resistance contacts on semiconducting TMDs such as MoS2. The large contact resistance limits the performance of devices. Unlike bulk materials, low contact resistance cannot be stably achieved in 2D materials by doping. Here we build on our previous work in which we demonstrated that it is possible to achieve low contact resistance electrodes by phase transformation. We show that similar to the previously demonstrated mechanically exfoliated samples, it is possible to decrease the contact resistance and enhance the FET performance by locally inducing and patterning the metallic 1T phase of MoS2 on chemically vapor deposited material. The device properties are substantially improved with 1T phase source/drain electrodes.

  10. Chemical Vapor Deposited Graphene-Based Derivative As High-Performance Hole Transport Material for Organic Photovoltaics.

    Science.gov (United States)

    Capasso, Andrea; Salamandra, Luigi; Faggio, Giuliana; Dikonimos, Theodoros; Buonocore, Francesco; Morandi, Vittorio; Ortolani, Luca; Lisi, Nicola

    2016-09-14

    The development of efficient charge transport layers is a key requirement for the fabrication of efficient and stable organic solar cells. A graphene-based derivative with planar resistivity exceeding 10(5) Ω/□ and work function of 4.9 eV is here produced by finely tuning the parameters of the chemical vapor deposition process on copper. After the growth, the film is transferred to glass/indium tin oxide and used as hole transport layer in organic solar cells based on a PBDTTT-C-T:[70]PCBM blend. The cells attained a maximum power conversion efficiency of 5%, matching reference cells made with state-of-the-art PSS as the hole transport layer. Our results indicate that functionalized graphene could represent an effective alternative to PSS as hole transport/electron blocking layer in solution-processed organic photovoltaics.

  11. Effects of potassium hydroxide post-treatments on the field-emission properties of thermal chemical vapor deposited carbon nanotubes.

    Science.gov (United States)

    Lee, Li-Ying; Lee, Shih-Fong; Chang, Yung-Ping; Hsiao, Wei-Shao

    2011-12-01

    In this study, a simple potassium hydroxide treatment was applied to functionalize the surface and to modify the structure of multi-walled carbon nanotubes grown on silicon substrates by thermal chemical vapor deposition. Scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and energy dispersive spectrometry were employed to investigate the mechanism causing the modified field-emission properties of carbon nanotubes. From our experimental data, the emitted currents of carbon nanotubes after potassium hydroxide treatment are enhanced by more than one order of magnitude compared with those of untreated carbon nanotubes. The emitted current density of carbon nanotubes increases from 0.44 mA/cm2 to 7.92 mA/cm2 after 30 minutes KOH treatment. This technique provides a simple, economical, and effective way to enhance the field-emission properties of carbon nanotubes.

  12. Passivated graphene transistors fabricated on a millimeter-sized single-crystal graphene film prepared with chemical vapor deposition

    International Nuclear Information System (INIS)

    Lin, Meng-Yu; Lee, Si-Chen; Lin, Shih-Yen; Wang, Cheng-Hung; Chang, Shu-Wei

    2015-01-01

    In this work, we first investigate the effects of partial pressures and flow rates of precursors on the single-crystal graphene growth using chemical vapor depositions on copper foils. These factors are shown to be critical to the growth rate, seeding density and size of graphene single crystals. The prepared graphene films in millimeter sizes are then bubbling transferred to silicon-dioxide/silicon substrates for high-mobility graphene transistor fabrications. After high-temperature annealing and hexamethyldisilazane passivation, the water attachment is removed from the graphene channel. The elimination of uncontrolled doping and enhancement of carrier mobility accompanied by these procedures indicate that they are promising for fabrications of graphene transistors. (paper)

  13. Si Nano wires Produced by Very High Frequency Plasma Enhanced Chemical Vapor Deposition (PECVD) via VLS Mechanism

    International Nuclear Information System (INIS)

    Yussof Wahab; Yussof Wahab; Habib Hamidinezhad; Habib Hamidinezhad

    2013-01-01

    Silicon nano wires (SiNWs) with diameter of about a few nanometers and length of 3 μm on silicon wafers were synthesized by very high frequency plasma enhanced chemical vapor deposition. Scanning electron microscopy (SEM) observations showed that the silicon nano wires were grown randomly and energy-dispersive X-ray spectroscopy analysis indicates that the nano wires have the composition of Si, Au and O elements. The SiNWs were characterized by high resolution transmission electron microscopy (HRTEM) and Raman spectroscopy. SEM micrographs displayed SiNWs that are needle-like with a diameter ranged from 30 nm at the top to 100 nm at the bottom of the wire and have length a few of micrometers. In addition, HRTEM showed that SiNWs consist of crystalline silicon core and amorphous silica layer. (author)

  14. On the Origin of Light Emission in Silicon Rich Oxide Obtained by Low-Pressure Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    M. Aceves-Mijares

    2012-01-01

    Full Text Available Silicon Rich Oxide (SRO has been considered as a material to overcome the drawbacks of silicon to achieve optical functions. Various techniques can be used to produce it, including Low-Pressure Chemical Vapor Deposition (LPCVD. In this paper, a brief description of the studies carried out and discussions of the results obtained on electro-, cathode-, and photoluminescence properties of SRO prepared by LPCVD and annealed at 1,100°C are presented. The experimental results lead us to accept that SRO emission properties are due to oxidation state nanoagglomerates rather than to nanocrystals. The emission mechanism is similar to Donor-Acceptor decay in semiconductors, and a wide emission spectrum, from 450 to 850 nm, has been observed. The results show that emission is a function of both silicon excess in the film and excitation energy. As a result different color emissions can be obtained by selecting the suitable excitation energy.

  15. Role of defects in tuning the electronic properties of monolayer WS{sub 2} grown by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jie; Zheliuk, Oleksandr; Lu, Jianming; Ye, Jianting [Zernike Institute for Advanced Materials, University of Groningen, Groningen (Netherlands); Gordiichuk, Pavlo [Zernike Institute for Advanced Materials, University of Groningen, Groningen (Netherlands); Department of Chemistry, Northwestern University, Evanston, IL (United States); Herrmann, Andreas [Zernike Institute for Advanced Materials, University of Groningen, Groningen (Netherlands); Molecular Biophysics, Department of Biology, Humboldt-Universitaet Berlin (Germany)

    2017-10-15

    Two-dimensional transition metal dichalcogenides have already attracted enormous research interest. To understand the dependence of electronic properties on the quality and defect morphology is vital for synthesizing high quality materials and the realization of functional devices. Here, we demonstrate the mapping of the conductive variations by conducting atomic force microscopy (C-AFM) in the monolayer tungsten disulfide (WS{sub 2}) grown by chemical vapor deposition. The electronic properties are strongly affected by the formation of vacancies in monolayer WS{sub 2} during growth, which is also verified by the photoluminescence. This spatial study of defects provides opportunities for optimization of the growth process for enhancing devices performance of TMDs monolayers. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Interwell coupling effect in Si/SiGe quantum wells grown by ultra high vacuum chemical vapor deposition

    Directory of Open Access Journals (Sweden)

    Loh Ter-Hoe

    2007-01-01

    Full Text Available AbstractSi/Si0.66Ge0.34coupled quantum well (CQW structures with different barrier thickness of 40, 4 and 2 nm were grown on Si substrates using an ultra high vacuum chemical vapor deposition (UHV-CVD system. The samples were characterized using high resolution x-ray diffraction (HRXRD, cross-sectional transmission electron microscopy (XTEM and photoluminescence (PL spectroscopy. Blue shift in PL peak energy due to interwell coupling was observed in the CQWs following increase in the Si barrier thickness. The Si/SiGe heterostructure growth process and theoretical band structure model was validated by comparing the energy of the no-phonon peak calculated by the 6 + 2-bandk·pmethod with experimental PL data. Close agreement between theoretical calculations and experimental data was obtained.

  17. Spark plasma sintering of cBN(core/SiO2(shell powder prepared by rotary chemical vapor deposition

    Directory of Open Access Journals (Sweden)

    Jianfeng Zhang

    2014-09-01

    Full Text Available SiO2 nanolayer coated cubic boron nitride (cBN, cBN(core/SiO2(shell powder, was prepared by rotary chemical vapor deposition. The cBN/SiO2 powder was densified by spark plasma sintering at 1873 K for 0.3 ks. The hexagonal boron nitride (hBN phase was not observed in the cBN–SiO2 composites, indicating that the SiO2 nanolayer depressed the phase transformation from cBN to hBN. The relative density of cBN–SiO2 increased with increasing SiO2 content (CSiO2. The highest hardness of the cBN–SiO2 composite was 17.5 GPa at CSiO2=38 wt% and a load of 0.98 N.

  18. Properties of Erbium Doped Hydrogenated Amorphous Carbon Layers Fabricated by Sputtering and Plasma Assisted Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    V. Prajzler

    2008-01-01

    Full Text Available We report about properties of carbon layers doped with Er3+ ions fabricated by Plasma Assisted Chemical Vapor Deposition (PACVD and by sputtering on silicon or glass substrates. The structure of the samples was characterized by X-ray diffraction and their composition was determined by Rutherford Backscattering Spectroscopy and Elastic Recoil Detection Analysis. The Absorbance spectrum was taken in the spectral range from 400 nm to 600 nm. Photoluminescence spectra were obtained using two types of Ar laser (λex=514.5 nm, lex=488 nm and also using a semiconductor laser (λex=980 nm. Samples fabricated by magnetron sputtering exhibited typical emission at 1530 nm when pumped at 514.5 nm. 

  19. Causal knowledge extraction by natural language processing in material science: a case study in chemical vapor deposition

    Directory of Open Access Journals (Sweden)

    Yuya Kajikawa

    2006-11-01

    Full Text Available Scientific publications written in natural language still play a central role as our knowledge source. However, due to the flood of publications, the literature survey process has become a highly time-consuming and tangled process, especially for novices of the discipline. Therefore, tools supporting the literature-survey process may help the individual scientist to explore new useful domains. Natural language processing (NLP is expected as one of the promising techniques to retrieve, abstract, and extract knowledge. In this contribution, NLP is firstly applied to the literature of chemical vapor deposition (CVD, which is a sub-discipline of materials science and is a complex and interdisciplinary field of research involving chemists, physicists, engineers, and materials scientists. Causal knowledge extraction from the literature is demonstrated using NLP.

  20. Epitaxial growth of CdTe thin film on cube-textured Ni by metal-organic chemical vapor deposition

    International Nuclear Information System (INIS)

    Gaire, C.; Rao, S.; Riley, M.; Chen, L.; Goyal, A.; Lee, S.; Bhat, I.; Lu, T.-M.; Wang, G.-C.

    2012-01-01

    Single crystal-like CdTe thin film has been grown by metalorganic chemical vapor deposition on cube-textured Ni(100) substrate. Using X-ray pole figure measurements we observed the epitaxial relationship of {111} CdTe //{001} Ni with [11 ¯ 0] CdTe //[010] Ni and [112 ¯ ] CdTe //[100] Ni . The 12 diffraction peaks in the (111) pole figure of CdTe film and their relative positions with respect to the four peak positions in the (111) pole figure of Ni substrate are consistent with four equivalent orientational domains of CdTe with three to four superlattice match of about 1.6% in the [11 ¯ 0] direction of CdTe and the [010] direction of Ni. The electron backscattered diffraction images show that the CdTe domains are 30° oriented from each other. These high structural quality films may find applications in low cost optoelectronic devices.

  1. Synthesis and growth mechanism of Fe-catalyzed carbon nanotubes by plasma-enhanced chemical vapor deposition

    International Nuclear Information System (INIS)

    Jiang Jun; Feng Tao; Cheng Xinhong; Dai Lijuan; Cao Gongbai; Jiang Bingyao; Wang Xi; Liu Xianghuai; Zou Shichang

    2006-01-01

    Plasma-enhanced chemical vapor deposition (PECVD) was used to grow Fe-catalyzed carbon nanotubes (CNTs). The nanotubes had a uniform diameter in the range of about 10-20 nm. A base growth mode was responsible for the CNTs growth using a mixture of H 2 (60 sccm) and C 2 H 2 (15 sccm). For a mixture of H 2 (100 sccm) and C 2 H 2 (25 sccm), a complicated growth mechanism took place involving both the base growth and the tip growth. X-ray photoelectron spectroscopy measurements revealed that the grown CNTs contained C-H covalent bonds and Fe-C bonds located at the interface between them and the substrates. The factors determining the growth mechanism of CNTs are discussed and their growth mechanisms with the different gas ratios are suggested

  2. Micro-light-emitting diodes with III–nitride tunnel junction contacts grown by metalorganic chemical vapor deposition

    KAUST Repository

    Hwang, David

    2017-12-13

    Micro-light-emitting diodes (µLEDs) with tunnel junction (TJ) contacts were grown entirely by metalorganic chemical vapor deposition. A LED structure was grown, treated with UV ozone and hydrofluoric acid, and reloaded into the reactor for TJ regrowth. The silicon doping level of the n++-GaN TJ was varied to examine its effect on voltage. µLEDs from 2.5 × 10−5 to 0.01 mm2 in area were processed, and the voltage penalty of the TJ for the smallest µLED at 20 A/cm2 was 0.60 V relative to that for a standard LED with indium tin oxide. The peak external quantum efficiency of the TJ LED was 34%.

  3. Growth of monolayer MoS2 films in a quasi-closed crucible encapsulated substrates by chemical vapor deposition

    Science.gov (United States)

    Yang, Yong; Pu, Hongbin; Lin, Tao; Li, Lianbi; Zhang, Shan; Sun, Gaopeng

    2017-07-01

    Monolayer molybdenum disulfide (m-MoS2) has attracted significant interest due to its unique electronic and optical properties. Herein, we report the successful fabrication of high quality and continuous m-MoS2 films in a quasi-closed crucible encapsulated substrates via a three-zone chemical vapor deposition (CVD) system. Quasi-closed crucible lowers the concentration of precursors around substrates and makes the sulfurization rate gentle, which is beneficial for invariable m-MoS2 growth. Characterization results indicate that as-grown m-MoS2 films are of high crystallinity and high quality comparable to the exfoliated MoS2. This approach is also adapted to the growth of other transition metal dichalcogenides.

  4. Controlled synthesis and properties of ZnO nanostructures grown by metalorganic chemical vapor deposition: A review

    Science.gov (United States)

    Park, Won Il

    2008-12-01

    The unique and fascinating properties of one-dimensional (1D) Zn) nanostructures have triggered tremendous interest in exploring their possibilities for future electronic and photonic device applications. This paper provides current information on the progress of ZnO nanostructure grown by metalorganic chemical vapor deposition (MOCVD); it covers issues ranging from controlled synthesis of various ZnO nanostructures to their properties and potential applications. The unique features of MOCVD have been exploited to grow high-quality 1D ZnO nanostructures with tunable sizes, enabling the study of excitonic dynamics in low-dimensional nanostructures and size-dependent quantum confinement. A better understanding of the growth behaviors of ZnO nanostructures—particularly the anisotropic surface energy and adsorbate-surface interaction with regard to the crystal planes—allows control over the positions, morphologies, and surface polarities of the ZnO nanostructures as appropriate for device integration.

  5. Controlling single and few-layer graphene crystals growth in a solid carbon source based chemical vapor deposition

    International Nuclear Information System (INIS)

    Papon, Remi; Sharma, Subash; Shinde, Sachin M.; Vishwakarma, Riteshkumar; Tanemura, Masaki; Kalita, Golap

    2014-01-01

    Here, we reveal the growth process of single and few-layer graphene crystals in the solid carbon source based chemical vapor deposition (CVD) technique. Nucleation and growth of graphene crystals on a polycrystalline Cu foil are significantly affected by the injection of carbon atoms with pyrolysis rate of the carbon source. We observe micron length ribbons like growth front as well as saturated growth edges of graphene crystals depending on growth conditions. Controlling the pyrolysis rate of carbon source, monolayer and few-layer crystals and corresponding continuous films are obtained. In a controlled process, we observed growth of large monolayer graphene crystals, which interconnect and merge together to form a continuous film. On the other hand, adlayer growth is observed with an increased pyrolysis rate, resulting few-layer graphene crystal structure and merged continuous film. The understanding of monolayer and few-layer crystals growth in the developed CVD process can be significant to grow graphene with controlled layer numbers.

  6. Method for Determining Vaporization Parameters

    Data.gov (United States)

    National Aeronautics and Space Administration — An accurate method of measuring vaporization coefficients will be very useful to each of these disciplines: Cosmochemistry,Evaporative Vapor Deposition, Durability...

  7. Metal-boride phase formation on tungsten carbide (WC-Co) during microwave plasma chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Johnston, Jamin M.; Catledge, Shane A., E-mail: catledge@uab.edu

    2016-02-28

    Graphical abstract: - Highlights: • A detailed phase analysis after PECVD boriding shows WCoB, CoB and/or W{sub 2}CoB{sub 2}. • EDS of PECVD borides shows boron diffusion into the carbide grain structure. • Nanoindentation hardness and modulus of borides is 23–27 GPa and 600–780 GPa. • Scratch testing shows hard coating with cracking at 40N and spallation at 70N. - Abstract: Strengthening of cemented tungsten carbide by boriding is used to improve the wear resistance and lifetime of carbide tools; however, many conventional boriding techniques render the bulk carbide too brittle for extreme conditions, such as hard rock drilling. This research explored the variation in metal-boride phase formation during the microwave plasma enhanced chemical vapor deposition process at surface temperatures from 700 to 1100 °C. We showed several well-adhered metal-boride surface layers consisting of WCoB, CoB and/or W{sub 2}CoB{sub 2} with average hardness from 23 to 27 GPa and average elastic modulus of 600–730 GPa. The metal-boride interlayer was shown to be an effective diffusion barrier against elemental cobalt; migration of elemental cobalt to the surface of the interlayer was significantly reduced. A combination of glancing angle X-ray diffraction, electron dispersive spectroscopy, nanoindentation and scratch testing was used to evaluate the surface composition and material properties. An evaluation of the material properties shows that plasma enhanced chemical vapor deposited borides formed at substrate temperatures of 800 °C, 850 °C, 900 °C and 1000 °C strengthen the material by increasing the hardness and elastic modulus of cemented tungsten carbide. Additionally, these boride surface layers may offer potential for adhesion of ultra-hard carbon coatings.

  8. Microstructure evolution of thermal spray WC–Co interlayer during hot filament chemical vapor deposition of diamond thin films

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Taimin [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Wei, Qiuping, E-mail: qpwei@csu.edu.cn [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Qi, Yao; Wang, Yijia; Xie, Youneng; Luo, Jiaqi [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Yu, Zhiming, E-mail: zhiming@csu.edu.cn [School of Materials Science and Engineering, Central South University, Changsha 410083 (China)

    2015-08-05

    Highlights: • Continuous and adherent diamond films are grown on WC–Co coated steel substrate. • Phase evolution rate of WC–Co coating is related to the coating depth. • Effect temperature on phase transition in WC–Co coating is presented. • Showed the differences between HFCVD and normal heat treatment of WC–Co coating. - Abstract: In this paper, diamond film was deposited on WC–Co coated steel substrate by hot filament chemical vapor deposition (HFCVD). This method can not only prepare diamond film on the sample, but also can be used as a new way of WC–Co coating heat treatment. Brittle phases, such as η phase, which were produced during ordinary heat treatment process, will be suppressed in HFCVD at high temperature. This paper systematically studied the microstructure (defects and phase) transition of WC–Co interlayer in the process of depositing diamond film. The mechanism of phase transition was discussed. The results showed that at high deposition temperature (e.g. 800 °C), the transition of binder phase was fast. After 5 h of deposition, the phase composition of WC–Co coating was almost the same as sintered WC–Co block. At low deposition temperature (e.g. 700 °C), the phase transition of interlayer slowed down and there was a large amount of nano-phases in the interlayer even after 12 h of deposition. Another notable feature is that phase transition of the surface part of interlayer was the fastest, followed by the inner part and the middle part was the slowest. The phase transition rate of the interlayer and the binder phase is closely related to the depth of the coating. In the surface part of the coating, Co will evaporate and diffuse into diamond film. Also, activated carbon atoms will diffuse into the interlayer, but the depth of diffusion layer was limited. Fe and Co will diffuse into each other at the interface between interlayer and steel substrate. In contrast, the middle part of interlayer was not affected by diffusion

  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

    , nickel, copper, titanium and aluminum. Calculation of the equilibrium composition of Ta-Cl-H-systems at 1000 K and 1100 K shows that TaCl4 and TaCl3 are stable at the deposition conditions and that a high yield (>90%) of tantalum is theoretically obtainable at low pressure (5 mbar) and moderate precursor...

  10. Characterization and cytocompatibility of carbon layers prepared by photo-induced chemical vapor deposition

    Czech Academy of Sciences Publication Activity Database

    Kubová, O.; Švorčík, V.; Heitz, J.; Moritz, S.; Romanin, C.; Matějka, P.; Macková, Anna

    2007-01-01

    Roč. 515, č. 17 (2007), s. 6765-6772 ISSN 0040-6090 R&D Projects: GA MŠk(CZ) LC06041 Institutional research plan: CEZ:AV0Z10480505 Keywords : Polytetrafluoroethylene * Carbon layer * CVD deposition * Layer properties * Cell proliferation Subject RIV: JJ - Other Materials Impact factor: 1.693, year: 2007

  11. Design, Modeling, Fabrication, and Evaluation of Thermoelectric Generators with Hot-Wire Chemical Vapor Deposited Polysilicon as Thermoelement Material

    Science.gov (United States)

    de Leon, Maria Theresa; Tarazona, Antulio; Chong, Harold; Kraft, Michael

    2014-11-01

    This paper presents the design, modeling, fabrication, and evaluation of thermoelectric generators (TEGs) with p-type polysilicon deposited by hot-wire chemical vapor deposition (HWCVD) as thermoelement material. A thermal model is developed based on energy balance and heat transfer equations using lumped thermal conductances. Several test structures were fabricated to allow characterization of the boron-doped polysilicon material deposited by HWCVD. The film was found to be electrically active without any post-deposition annealing. Based on the tests performed on the test structures, it is determined that the Seebeck coefficient, thermal conductivity, and electrical resistivity of the HWCVD polysilicon are 113 μV/K, 126 W/mK, and 3.58 × 10-5 Ω m, respectively. Results from laser tests performed on the fabricated TEG are in good agreement with the thermal model. The temperature values derived from the thermal model are within 2.8% of the measured temperature values. For a 1-W laser input, an open-circuit voltage and output power of 247 mV and 347 nW, respectively, were generated. This translates to a temperature difference of 63°C across the thermoelements. This paper demonstrates that HWCVD, which is a cost-effective way of producing solar cells, can also be applied in the production of TEGs. By establishing that HWCVD polysilicon can be an effective thermoelectric material, further work on developing photovoltaic-thermoelectric (PV-TE) hybrid microsystems that are cost-effective and better performing can be explored.

  12. Impact of microcrystalline silicon carbide growth using hot-wire chemical vapor deposition on crystalline silicon surface passivation

    International Nuclear Information System (INIS)

    Pomaska, M.; Beyer, W.; Neumann, E.; Finger, F.; Ding, K.

    2015-01-01

    Highly crystalline microcrystalline silicon carbide (μc-SiC:H) with excellent optoelectronic material properties is a promising candidate as highly transparent doped layer in silicon heterojunction (SHJ) solar cells. These high quality materials are usually produced using hot wire chemical vapor deposition under aggressive growth conditions giving rise to the removal of the underlying passivation layer and thus the deterioration of the crystalline silicon (c-Si) surface passivation. In this work, we introduced the n-type μc-SiC:H/n-type μc-SiO x :H/intrinsic a-SiO x :H stack as a front layer configuration for p-type SHJ solar cells with the μc-SiO x :H layer acting as an etch-resistant layer against the reactive deposition conditions during the μc-SiC:H growth. We observed that the unfavorable expansion of micro-voids at the c-Si interface due to the in-diffusion of hydrogen atoms through the layer stack might be responsible for the deterioration of surface passivation. Excellent lifetime values were achieved under deposition conditions which are needed to grow high quality μc-SiC:H layers for SHJ solar cells. - Highlights: • High surface passivation quality was preserved after μc-SiC:H deposition. • μc-SiC:H/μc-SiO x :H/a-SiO x :H stack a promising front layer configuration • Void expansion at a-SiO x :H/c-Si interface for deteriorated surface passivation • μc-SiC:H provides a high transparency and electrical conductivity.

  13. An automatic system using mobile-agent software to model the calculation process of a chemical vapor deposition film deposition simulator.

    Science.gov (United States)

    Takahashi, Takahiro; Fukui, Noriyuki; Arakawa, Masamoto; Funatsu, Kimito; Ema, Yoshinori

    2011-09-01

    We have developed an automatic modeling system for calculation processes of the simulator to reproduce experimental results of chemical vapor deposition (CVD), in order to decrease the calculation cost of the simulator. Replacing the simulator by the mathematical models proposed by the system will contribute towards decreasing the calculation costs for predicting the experimental results. The system consists of a mobile agent and two software resources in computer networks, that is, generalized modeling software and a simulator reproducing cross-sections of the deposited films on the substrates with the micrometer- or nanometer-sized trenches. The mobile agent autonomously creates appropriate models by moving to and then operating the software resources. The models are calculated by partial least squares regression (PLS), quadratic PLS (QPLS) and error back propagation (BP) methods using artificial neural networks (ANN) and expresses by mathematical formulas to reproduce the calculated results of the simulator. The models show good reproducibility and predictability both for uniformity and filling properties of the films calculated by the simulator. The models using the BP method yield the best performance. The filling property data are more suitable to modeling than film uniformity.

  14. Physical vapor deposited thin films of lignins extracted from sugar cane bagasse: morphology, electrical properties, and sensing applications.

    Science.gov (United States)

    Volpati, Diogo; Machado, Aislan D; Olivati, Clarissa A; Alves, Neri; Curvelo, Antonio A S; Pasquini, Daniel; Constantino, Carlos J L

    2011-09-12

    The concern related to the environmental degradation and to the exhaustion of natural resources has induced the research on biodegradable materials obtained from renewable sources, which involves fundamental properties and general application. In this context, we have fabricated thin films of lignins, which were extracted from sugar cane bagasse via modified organosolv process using ethanol as organic solvent. The films were made using the vacuum thermal evaporation technique (PVD, physical vapor deposition) grown up to 120 nm. The main objective was to explore basic properties such as electrical and surface morphology and the sensing performance of these lignins as transducers. The PVD film growth was monitored via ultraviolet-visible (UV-vis) absorption spectroscopy and quartz crystal microbalance, revealing a linear relationship between absorbance and film thickness. The 120 nm lignin PVD film morphology presented small aggregates spread all over the film surface on the nanometer scale (atomic force microscopy, AFM) and homogeneous on the micrometer scale (optical microscopy). The PVD films were deposited onto Au interdigitated electrode (IDE) for both electrical characterization and sensing experiments. In the case of electrical characterization, current versus voltage (I vs V) dc measurements were carried out for the Au IDE coated with 120 nm lignin PVD film, leading to a conductivity of 3.6 × 10(-10) S/m. Using impedance spectroscopy, also for the Au IDE coated with the 120 nm lignin PVD film, dielectric constant of 8.0, tan δ of 3.9 × 10(-3), and conductivity of 1.75 × 10(-9) S/m were calculated at 1 kHz. As a proof-of-principle, the application of these lignins as transducers in sensing devices was monitored by both impedance spectroscopy (capacitance vs frequency) and I versus time dc measurements toward aniline vapor (saturated atmosphere). The electrical responses showed that the sensing units are sensible to aniline vapor with the process being

  15. High-quality AlN films grown on chemical vapor-deposited graphene films

    Directory of Open Access Journals (Sweden)

    Chen Bin-Hao

    2016-01-01

    Full Text Available We report the growth of high-quality AlN films on graphene. The graphene films were synthesized by CVD and then transferred onto silicon substrates. Epitaxial aluminum nitride films were deposited by DC magnetron sputtering on both graphene as an intermediate layer and silicon as a substrate. The structural characteristics of the AlN films and graphene were investigated. Highly c-axis-oriented AlN crystal structures are investigated based on the XRDpatterns observations.

  16. Hybrid Physical Vapor Deposition Instrument for Advanced Functional Multilayers and Materials

    Science.gov (United States)

    2016-04-27

    AUTHORS 7. PERFORMING ORGANIZATION NAMES AND ADDRESSES 15. SUBJECT TERMS b. ABSTRACT 2. REPORT TYPE 17. LIMITATION OF ABSTRACT 15. NUMBER OF PAGES...The instrumentation enables clean, uniform, and rapid deposition of a wide variety of metallic, semiconducting , and ceramic thin films with...ACRONYM(S) ARO 8. PERFORMING ORGANIZATION REPORT NUMBER 19a. NAME OF RESPONSIBLE PERSON 19b. TELEPHONE NUMBER Jon-Paul Maria Jon-Paul Maria 611103

  17. Tribological and thermal stability study of nanoporous amorphous boron carbide films prepared by pulsed plasma chemical vapor deposition

    Science.gov (United States)

    Liza, Shahira; Ohtake, Naoto; Akasaka, Hiroki; Munoz-Guijosa, Juan M.

    2015-06-01

    In this work, the thermal stability and the oxidation and tribological behavior of nanoporous a-BC:H films are studied and compared with those in conventional diamond-like carbon (DLC) films. a-BC:H films were deposited by pulsed plasma chemical vapor deposition using B(CH3)3 gas as the boron source. A DLC interlayer was used to prevent the a-BC:H film delamination produced by oxidation. Thermal stability of a-BC:H films, with no delamination signs after annealing at 500 °C for 1 h, is better than that of the DLC films, which completely disappeared under the same conditions. Tribological test results indicate that the a-BC:H films, even with lower nanoindentation hardness than the DLC films, show an excellent boundary oil lubricated behavior, with lower friction coefficient and reduce the wear rate of counter materials than those on the DLC film. The good materials properties such as low modulus of elasticity and the formation of micropores from the original nanopores during boundary regimes explain this better performance. Results show that porous a-BC:H films may be an alternative for segmented DLC films in applications where severe tribological conditions and complex shapes exist, so surface patterning is unfeasible.

  18. Selective adhesion of intestinal epithelial cells on patterned films with amine functionalities formed by plasma enhanced chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyung Seop; Choi, Changrok; Kim, Soo Heon; Choi, Kun oh [Department of Physics, Brain Korea 21 Physics Research Division and Institute of Basic Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Kim, Jeong Min [Department of Molecular Biology and Institute of Nanosensor and Biotechnology, BK21 Graduate Program for RNA Biology, Dankook University, Yongin 448-701 (Korea, Republic of); Kim, Hong Ja [Department of Internal Medicine, Dankook University College of Medicine, Cheonan 330-715 (Korea, Republic of); Yeo, Sanghak [R and D Center, ELBIO Incorporation, 426-5 Gasan-dong Geumchun-gu, Seoul (Korea, Republic of); Park, Heonyong [Department of Molecular Biology and Institute of Nanosensor and Biotechnology, BK21 Graduate Program for RNA Biology, Dankook University, Yongin 448-701 (Korea, Republic of); Jung, Donggeun, E-mail: djung@skku.ac.kr [Department of Physics, Brain Korea 21 Physics Research Division and Institute of Basic Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2010-11-01

    Control of cell adhesion to surfaces is important to develop analytical tools in the areas of biomedical engineering. To control cell adhesiveness of the surface, we constructed a variety of plasma polymerized hexamethyldisiloxane (PPHMDSO) thin films deposited at the plasma power range of 10-100 W by plasma enhanced chemical vapor deposition (PECVD). The PPHMDSO film that was formed at 10 W was revealed to be resistant to cell adhesion. The resistance to cell adhesion is closely related to physicochemical properties of the film. Atomic force microscopic data show an increase in surface roughness from 0.52 nm to 0.74 nm with increasing plasma power. From Fourier transform infrared (FT-IR) absorption spectroscopy data, it was also determined that the methyl (-CH{sub 3}) peak intensity increases with increasing plasma power, whereas the hydroxyl (-OH) peak decreases. X-ray photoelectron spectroscopy data reveal an increase in C-O bonding with increasing plasma power. These results suggest that C-O bonding and hydroxyl (-OH) and methyl (-CH{sub 3}) functional groups play a critical part in cell adhesion. Furthermore, to enhance a diversity of film surface, we accumulated the patterned plasma polymerized ethylenediamine (PPEDA) thin film on the top of the PPHMDSO thin film. The PPEDA film is established to be strongly cell-adherent. This patterned two-layer film stacking method can be used to form the selectively limited cell-adhesive PPEDA spots over the adhesion-resistant surface.

  19. Atmospheric pressure chemical vapor deposition mechanism of Al 2O 3 film from AlCl 3 and O 2

    Science.gov (United States)

    Nasution, Indra; Velasco, Angelito; Kim, Hee-joon

    2009-01-01

    Aluminum oxide (Al 2O 3) films were deposited by atmospheric pressure chemical vapor deposition (AP-CVD) method from aluminum trichloride (AlCl 3), argon, and oxygen gas mixtures at temperatures ranging from 800 to 1000 °C. Alumina films with crystalline phases of γ- or θ-, and α-alumina were obtained starting at 800 °C. Increase in the relative amount of the α-phase as well as improvement in crystallinity is observed as temperature is increased to 1000 °C. The films have low chlorine content, which continued to decrease with increasing temperature. Analysis of the film growth rate on tubular substrates of varying diameters revealed a diffusion-limited growth from 800 to 950 °C and gas-phase reaction-limited growth at 1000 °C. The growth species is a cluster with size 1.2 nm at 800 °C and 0.9 nm at 950 °C. The gas-phase reaction constant at 1000 °C is 1.1/s.

  20. Epitaxial growth of BaTiO3 thin films by plasma-enhanced metalorganic chemical vapor deposition

    Science.gov (United States)

    Chern, C. S.; Zhao, J.; Luo, L.; Lu, P.; Li, Y. Q.; Norris, P.; Kear, B.; Cosandey, F.; Maggiore, C. J.; Gallois, B.; Wilkens, B. J.

    1992-03-01

    High-quality BaTiO3 thin films have been epitaxially grown on (001) LaAlO3 and (001) NdGaO3 substrates by plasma-enhanced metalorganic chemical vapor deposition at a substrate temperature of 680 °C. X-ray diffraction θ-2θ, ω, and φ scan results all indicate that single-crystalline BaTiO3 thin films were epitaxially grown on the substrates with orientation perpendicular to the substrates. The high degree of epitaxial crystallinity is further confirmed by Rutherford backscattering spectrometry which gives a minimum yield of 7.5% and 11% for films deposited on LaAlO3 and NdGaO3, respectively. Cross-section high-resolution electron microscopy images also showed that the layer epitaxy of BaTiO3 was characterized by an atomically abrupt film/substrate interface. Scanning electron micrographs showed that these films had very smooth surface morphologies.