Home About us Contact
|
Home About us Contact | ||
|
|
||
Chemical Vapor Deposition (chemical + vapor_deposition)
Kinds of Chemical Vapor Deposition Terms modified by Chemical Vapor Deposition Selected AbstractsThe Critical Role of the Underlayer Material and Thickness in Growing Vertically Aligned Carbon Nanotubes and Nanofibers on Metallic Substrates by Chemical Vapor DepositionADVANCED FUNCTIONAL MATERIALS, Issue 8 2010Gilbert D. Nessim Abstract Vertically aligned carbon nanotubes and nanofibers are grown on metallic Ta and Pd underlayers at temperatures below 500,°C. Controlling the size of the grains of the underlayer film is critical because this leads to a more uniform distribution of catalyst dots, which in turn results in vertical alignment of the carbon nanostructures. Rapid and limited heating and appropriate materials selection can also be used to limit catalyst/underlayer reactions that hinder or suppress carbon nanostructure growth or that lead to entangled growth. Control of catalyst reactivity with metallic underlayers is significant because growth on conductive substrates is notoriously difficult, but needed for many applications such as the use of carbon nanostructures in microelectronic circuits. [source] Synthesis of Poly(4-vinylpyridine) Thin Films by Initiated Chemical Vapor Deposition (iCVD) for Selective Nanotrench-Based Sensing of NitroaromaticsADVANCED FUNCTIONAL MATERIALS, Issue 7 2010Wyatt E. Tenhaeff Abstract A new nanoscale sensing concept for the detection of nitroaromatic explosives is described. The design consists of nitroaromatic-selective polymeric layers deposited inside microfabricated trenches. As the layers are exposed to nitroaromatic vapors, they swell and contact each other to close an electrical circuit. The nitroaromatic selective polymer, poly(4-vinylpyridine) (P4VP), is deposited in the trenches using initiated chemical vapor deposition (iCVD). P4VP is characterized for the first time as a selective layer for the absorption of nitroaromatic vapors. The Flory,Huggins equation is used to model the swelling response to nitroaromatic vapors. The Flory,Huggins interaction parameter for the P4VP,nitrobenzene system at 40,°C is 0.71 and 0.25 for P4VP,4-nitrotoluene at 60,°C. Sensing of nitrobenzene vapors is demonstrated in a prototype device, while techniques to improve the performance of the design in terms of response time and sensitivities are described. Modeling shows that concentration and mass limits of detection of 0.95,ppb and 3 fg, respectively, can be achieved. [source] Ultralow Dielectric Constant Tetravinyltetramethylcyclotetrasiloxane Films Deposited by Initiated Chemical Vapor Deposition (iCVD)ADVANCED FUNCTIONAL MATERIALS, Issue 4 2010Nathan J. Trujillo Abstract Simultaneous improvement of mechanical properties and lowering of the dielectric constant occur when films grown from the cyclic monomer tetravinyltetramethylcyclotetrasiloxane (V4D4) via initiated chemical vapor deposition (iCVD) are thermally cured in air. Clear signatures from silsesquioxane cage structures in the annealed films appear in the Fourier transform IR (1140,cm,1) and Raman (1117,cm,1) spectra. The iCVD method consumes an order of magnitude lower power density than the traditional plasma-enhanced CVD, thus preserving the precursor's delicate ring structure and organic substituents in the as-deposited films. The high degree of structural retention in the as-deposited film allows for the beneficial formation of intrinsically porous silsesquioxane cages upon annealing in air. Complete oxidation of the silicon creates ,Q' groups, which impart greater hardness and modulus to the films by increasing the average connectivity number of the film matrix beyond the percolation of rigidity. The removal of labile hydrocarbon moieties allows for the oxidation of the as-deposited film while simultaneously inducing porosity. This combination of events avoids the typical trade-off between improved mechanical properties and higher dielectric constants. Films annealed at 410,°C have a dielectric constant of 2.15, and a hardness and modulus of 0.78 and 5.4,GPa, respectively. The solvent-less and low-energy nature of iCVD make it attractive from an environmental safety and health perspective. [source] Synthesis of Large-Area Graphene Layers on Poly-Nickel Substrate by Chemical Vapor Deposition: Wrinkle FormationADVANCED MATERIALS, Issue 22 2009Seung Jin Chae Large-area, few-layer graphene is grown on a poly-nickel substrate using optimized CVD conditions. High temperature, short growth time, and an optimal gas mixing ratio (C2H2/H2,=,2/45) are found to be necessary to synthesize highly crystalline few-layer grapheme, which may find applications in electronic devices. The wrinkles that are observed under all growth conditions are proposed to be formed by two processes. [source] Copper Nanowires with a Five-Twinned Structure Grown by Chemical Vapor Deposition,ADVANCED MATERIALS, Issue 10 2008Changwook Kim Freestanding copper nanowires (CuNWs) grown by CVD are analyzed by electron microscopy to show the details of a fivefold-twinned structure. The electron diffraction pattern discloses irregular mismatching of the twin boundaries. The electron emission characteristics of the CuNWs are presented, along with a CuNW-based proof-of-principle field-emission display (see figure). [source] Self-Assembled Si Quantum-Ring Structures on a Si Substrate by Plasma-Enhanced Chemical Vapor Deposition Based on a Growth-Etching Competition MechanismADVANCED MATERIALS, Issue 18 2007W. Yu No abstract is available for this article. [source] Large-Scale Synthesis of Rings of Bundled Single-Walled Carbon Nanotubes by Floating Chemical Vapor Deposition,ADVANCED MATERIALS, Issue 14 2006L. Song Rings of bundled single-walled carbon nanotubes with perfectly toroidal geometries (see figure), are fabricated in high yields by a floating chemical vapor deposition process involving the thermal decomposition of acetylene. The nanotube rings can be grown with varying densities on a wide variety of substrates at relatively low temperatures, which is a significant advantage for nanoelectronics applications. [source] Photocatalysis Using ZnO Thin Films and Nanoneedles Grown by Metal,Organic Chemical Vapor Deposition,ADVANCED MATERIALS, Issue 18 2004L. Yang Highly efficient photocatalytic ZnO nanoneedle arrays with a large surface/volume ratio were prepared on inexpensive, large-area substrates using metal,organic chemical vapor deposition. The photocatalytic activity of ZnO nanoneedle arrays is much enhanced due to their increased surface/volume ratio. It is believed that the "bottom,up" approach may be expanded to create many other one-dimensional oxide semiconductor nanostructures (see Figure). [source] High-Quality Ultra-Fine GaN Nanowires Synthesized Via Chemical Vapor Deposition (Adv. Mater.ADVANCED MATERIALS, Issue 12 2004Abstract To view the original paper use http://dx.doi.org/10.1002/adma.200390097. [source] Ordered Mesoporous Carbon Hollow Spheres Nanocast Using Mesoporous Silica via Chemical Vapor Deposition,ADVANCED MATERIALS, Issue 11 2004D. Xia Hollow spheres of well-ordered mesoporous carbon (see Figure) may be obtained via a simple chemical vapor deposition route, which utilizes mesoporous silica SBA-15 as a solid template and suitable organic compounds (e.g., styrene) as the carbon source. [source] Deposition Mechanism for Chemical Vapor Deposition of Zirconium Carbide CoatingsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2008Yiguang Wang Zirconium carbide (ZrC) coatings were fabricated by chemical vapor deposition (CVD) using ZrCl4, CH4/C3H6, and H2 as precursors. Both thermodynamic calculation results and the film compositions at different temperatures indicated that zirconium and carbon deposited separately during the CVD process. The ZrC deposition rates were measured for CH4 or C3H6 as carbon sources at different temperatures based on coating thickness. The activation energies for ZrC deposition demonstrated that the CVD ZrC process is controlled by the carbon deposition. This is also proven by the morphologies of ZrC coatings. [source] Aluminum Silicate Films Obtained by Low-Pressure Metal-Organic Chemical Vapor DepositionJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2003Dong-Hau Kuo Amorphous alumina-silica films with film thickness of 0.41,2.69 ,m were prepared on glass and silicon substrates by metal-organic chemical vapor deposition using a mixture of aluminum tri-sec-butoxide (ATSB), hexamethyldisilazane (HMDSN), and argon. By controlling the inputs of ATSB and HMDSN, alumina-silica thin films could contain varied compositions and adjustable properties. Basically, the codeposition of alumina and silica to form alumina-silica using ATSB and HMDSN had a faster growth rate than their individual components. The internal stress could be adjusted by deposition temperature and reactant inputs. Adhesion could be improved by having a silicon-rich thin film, whereas an aluminum-rich film could have slightly higher hardness. Optical properties, e.g., refractive index and optical transmittance, were also measured. [source] Fracture Strength of Plate and Tubular Forms of Monolithic Silicon Carbide Produced by Chemical Vapor DepositionJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2002Brian Vern Cockeram The fracture strength of silicon carbide (SiC) plate deposits produced by chemical vapor deposition (CVD) was determined from room temperature to 1500°C using a standard 4-point flexural test method (ASTM C1161). CVD SiC materials produced by two different manufacturers are shown to have only slightly different flexural strength values, which appear to result from differences in microstructure. Although CVD deposition of SiC results in a textured grain structure, the flexural strength was shown to be independent of the CVD growth direction. The orientation of machining marks was shown to have the most significant influence on flexural strength, as expected. The fracture strength of tubular forms of SiC produced by CVD deposition directly onto a mandrel was comparable to flexural bars machined from a plate deposit. The tubular (O-ring) specimens were much smaller in volume than the flexural bars, and higher strength values are predicted based on Weibull statistical theory for the O-ring specimens. Differences in microstructure between the plate deposits and deposits made on a mandrel result in different flaw distributions and comparable strength values for the flexural bar and O-ring specimens. These results indicate that compression testing of O-rings provides a more accurate strength measurement for tubular product forms of SiC due to more representative flaw distributions. [source] Cross-Linking and Degradation Properties of Plasma Enhanced Chemical Vapor Deposited Poly(2-hydroxyethyl methacrylate)MACROMOLECULAR RAPID COMMUNICATIONS, Issue 2 2009Courtney A. Pfluger Abstract Plasma Enhanced Chemical Vapor Deposition (PECVD) of poly-2-hydroxyethyl methacrylate (pHEMA) biocompatible, biodegradable polymer films were produced alone and cross-linked with ethylene glycol diacrylate (EGDA). Degree of cross-linking was controlled via manipulation of the EGDA flow rate, which influenced the amount of swelling and the extent of degradation of the films in an aqueous solution over time. Noncross-linked pHEMA films swelled 10% more than cross-linked films after 24 h of incubation in an aqueous environment. Increasing degree of film cross-linking decreased degradation over time. Thus, PECVD pHEMA films with variable cross-linking properties enable tuning of gel formation and degradation properties, making these films useful in a variety of biologically significant applications. [source] Growth and properties of nanocrystalline diamond filmsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 13 2006Oliver A. Williams Abstract The aim of this paper is to summarise recent progress in the growth of small grain-sized Chemical Vapor Deposition (CVD) diamond often called nanocrystalline diamond, i.e., diamond with grains typically smaller than 500 nm. Nanocrystalline (NCD) and Ultrananocrystalline diamond (UNCD) films are new materials offering interesting applications to nanobioelectronics and electrochemistry. However NCD and UNCD thin films comprise of entirely different structures which is highlighted here in this paper. We discuss in detail the main differences in Raman spectra, optical properties and electrical transport properties. Finally we present a simple model of the conductivity mechanism in nitrogenated UNCD (N-UNCD) and boron doped NCD (B-NCD) films, and show the possibility of achieving the superconductive transition in B-NCD films. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Optimized-geometry ARROW waveguides using TiO2 as anti-resonant layerPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3-4 2010Daniel O. Carvalho Abstract The simulation, fabrication and characterization of ARROW waveguides using dielectric films deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD) and Sputtering techniques, are presented in this work. Amorphous titanium oxide (TiO2) films were used as first cladding layer and silicon oxynitride (SiOxNy) films, as core layer. Furthermore, homemade routines based in two computational methods were used, for numerical simulations: Transfer Matrix Method (TMM) for the determination of the optimum thickness values of the Fabry-Perot layers, and the Finite Difference Method (FDM) for 2D design and determination of the maximum width that allows single-mode operation. The utilization of thermally grown silicon oxide as second anti-resonant layer, along with improvements in the Reactive Ion Etching conditions for the definition of sidewalls of the optical waveguides were responsible for diminishing optical attenuations. Optimization of the waveguide rib height was done both through FDM simulations and experimentally. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Growth of Fe doped semi-insulating GaN on sapphire and 4H-SiC by MOCVDPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2006M. Rudzi Abstract We report a study of iron doped GaN layers grown on sapphire and SiC by Metal Organic Chemical Vapor Deposition (MOCVD) using ferrocene as the Fe precursor. The influence of iron doping on the electrical, structural and morphological properties of the GaN layers was studied. A resistivity of 6x103 ,cm and higher was achieved in contrast to 3 ,cm for the undoped film. Defect selective etching showed that Fe doping increases the threading dislocation (TD) density which might be responsible for the increase in resistivity. A turn-on, turn-off effect is described and a memory effect which is responsible for a decrease of the surface quality of the samples. In situ annealing of the susceptor and the use of a clean liner after each growth run helps to reduce this effect and maintain the good quality of GaN layers. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] InAs quantum dot formed on GaNAs buffer layer by Metalorganic Chemical Vapor DepositionPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3 2006R. Suzuki Abstract We investigated MOCVD grown InAs QDs on a GaNAs buffer layer. Distribution uniformity and shape of QDs on buffer layers were characterized for different nitrogen (N) compositions from 0% to 2%. It was found that the distribution of QDs on a GaNAs buffer layer became more uniform than that on a GaAs and the coalescence of QDs was suppressed. Increase of the aspect ratio (diameter/height) was also observed by increase of N composition. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Single-Chamber Deposition of Multilayer Barriers by Plasma Enhanced and Initiated Chemical Vapor Deposition of OrganosiliconesPLASMA PROCESSES AND POLYMERS, Issue 7 2010Anna Maria Coclite Abstract A novel technique, combining the plasma assisted deposition of SiOx -like coatings with the initiated chemical vapor deposition (iCVD) of organosilicon films in a single-chamber process, was investigated for the production of multistack barriers against the water vapor permeation. Hexavinyldisiloxane (HVDSO) was used as the film precursor for both kinds of polymerization. iCVD of HVDSO resulted in highly crosslinked and adherent carbon-rich polymer which reduced the substrate roughness of the substrate, thus acting as a primer for the deposition of the denser C-depleted uplayer. The plasma ion bombardment of the C-rich underlayer produced a graded interphase which enhanced the adhesion between the layers and of the multilayer stack to the polymer substrate. The C-rich interlayers effectively decoupled the defects of the C-depleted layers, indeed a barrier improvement factor of 100 over the single C-depleted barrier layer was obtained with a hexalayer structure. [source] Effect of Substrate Temperature and RF Biasing on the Optical Properties of Titania-Like Thin Films Obtained by Plasma Enhanced Chemical Vapor DepositionPLASMA PROCESSES AND POLYMERS, Issue S1 2009Axel Sonnenfeld Abstract A low pressure radio frequency (RF) discharge (200,W) was operated in argon/oxygen with small admixtures of titanium(IV)isopropoxide (TTIP). By regulating the cooling temperature of the RF driven electrode, the influence of the substrate temperature and of the ion bombardment caused by the negative DC self-bias of the RF electrode was investigated comparatively. Thin titania-like films were obtained and characterized with respect to their cut-off wavelength and their spectral absorption coefficient in the UV range. Accordingly, the cut-off wavelength was found to be higher for films obtained on the DC-self-biased electrode. Here, its value appears independent of the substrate temperature and attained successively its maximum at 340,nm with deposition time. Furthermore, the absorption coefficients of films deposited on the DC self-biased electrode are well superior to those obtained on the grounded substrate holder. [source] Special Issue on Aerosol-Assisted Chemical Vapor DepositionCHEMICAL VAPOR DEPOSITION, Issue 10 2006Kwang-Leong Choy As a variant of conventional CVD, AACVD involves atomization of a liquid precursor into fine aerosol droplets that are delivered to a heated zone where evaporation, decomposition, and subsequent CVD reactions occur. In this editorial, Guest Editor Kwang-Leong Choy provides a brief overview of the articles in this Special Issue and some of the recent advances in this dynamic field. [source] Special Issue on Carbon NanotubesCHEMICAL VAPOR DEPOSITION, Issue 6 2006L. Terranova Abstract Carbon Nanotubes are the topic of this Special Issue of Chemical Vapor Deposition. In this introduction, Guest Editor Maria Letizia Terranova highlights the potential of nanostructured carbon materials and comments on the importance of CVD synthesis techniques in this ever- expanding field. [source] Editorial: Special Issue on High-Permittivity Dielectric OxidesCHEMICAL VAPOR DEPOSITION, Issue 2-3 2006C. Jones Abstract High-permittivity dielectric oxides is the theme of this Special Issue of Chemical Vapor Deposition. In this Editorial, Tony Jones recaps the search for an alternative to SiO2 as a dielectric layer for the electronics industry, and introduces the papers presented in the Special Issue as an overview of current research directions in the MOCVD and ALD of a wide range of high- k dielectric oxides. The breadth of materials and resultant electronic properties reported confirm that the jury is still out regarding the final choice of oxide for the next generation of microelectronics. [source] Kinetics and Film Properties of Boron Nitride Derived from Trimethoxyborane/Ammonia by Chemical Vapor Deposition,CHEMICAL VAPOR DEPOSITION, Issue 6 2004H. Strakov Abstract The kinetics of the CVD of boron nitride from trimethoxyborane (TMOB) and ammonia (NH3) under atmospheric pressure was investigated by varying the following process parameters: temperature, residence time of the reactants, molar fraction of TMOB, and the NH3/TMOB ratio, ,. A kinetic power law equation was derived, that describes the experimental results with good accuracy. The reaction order with respect to TMOB is found to be 0.9 and ,,0.2 with respect to NH3. Between 800,°C and 950,°C, the deposition rate is controlled by the surface reaction kinetics with apparent activation energy of 115.1,kJ,mol,1. The deposited BN films were characterized by IR spectroscopy, Raman spectroscopy, and X-ray diffraction (XRD). The microstructure of the deposits depends on the nature of the substrates used. Turbostratic boron nitride (t-BN) was deposited on graphite, and hexagonal boron nitride (h-BN) on alumina substrates. X-ray photoelectron spectroscopy (XPS) analyses show nearly stoichiometric BN films for deposition temperatures in the range 850,950,°C for high amounts of ammonia (100,<,,,<,150) in the feed gas. [source] Effects of an Added Iodine Source (C2H5I) on Ru Metal,Organic Chemical Vapor Deposition,CHEMICAL VAPOR DEPOSITION, Issue 2 2003J.J. Kim Abstract The effects of an iodine source (C2H5I) on ruthenium (Ru) films grown on TiN/Ti/Si wafers by metal,organic (MO)CVD using Ru(EtCp)2 as a precursor were investigated. When an additional step of adsorbing iodine source was inserted during the Ru MOCVD process, the films became smoother and the root mean square (rms) surface roughness of the 30,nm thick Ru film became less than 10,% of the film thickness, as low as 1.71,nm. Moreover, the surface reaction-limited regime was extended to 400,°C, causing a wide process window. [source] Metallorganic Chemical Vapor Deposition of Ru Films Using Cyclopentadienyl-Propylcyclopentadienylruthenium(II) and Oxygen.CHEMINFORM, Issue 38 2002Sang Yeol Kang Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Chemical Vapor Deposition of Gallium Nitride from the GaCl3 + NH3 System.CHEMINFORM, Issue 30 2002Theoretical Study of the Structure, Thermodynamics of Potential Intermediates Formed in the Gaseous Phase. Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: DFT Modeling of Chemical Vapor Deposition of GaN from Organogallium Precursors.CHEMINFORM, Issue 28 2001Part 2. Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: DFT Modeling of Chemical Vapor Deposition of GaN from Organogallium Precursors.CHEMINFORM, Issue 25 2001Part 1. Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Cracking study of pentakis(dimethylamino)tantalum vapors by Knudsen cell mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 20 2010Perrine Violet Organometallic molecules are commonly used as gaseous precursors in Atomic Layer Deposition/Chemical Vapor Deposition (ALD/CVD) processes. However, the use of these molecules, which are generally thermally unstable at temperatures close to the deposition temperature, requires an understanding of their gas-phase chemical behavior. The thermal cracking of the gaseous precursor, pentakis(dimethylamino) tantalum (PDMAT), generally adopted in the ALD/CVD TaN deposition processes, has been studied in the temperature range from 343 to 723K using a specific reactor coupled with a high-temperature mass spectrometer. This reactor , built as tandem Knudsen cells , consists of two superimposed cells. The first stage reactor , an evaporation cell , provides an input saturated vapor flow operating from room temperature to 333K. The second stage cell, named the cracking cell, operated from 333 to 723K in the present study. Experiments showed the appearance of many gaseous species when the cracking temperature increased and, in particular, dimethylamine, corresponding to the saturated organic branches of PDMAT. Decomposition products of the HNC2H6 branch were observed at relatively high temperature, namely above 633K. This gas-phase study , as for the preceding saturated one , shows the presence of oxygen-containing molecules in PDMAT cracked vapor. Thus, it explains the systematic presence of oxygen contamination in the deposited TaN films observed in ALD/CVD industrial processes. Copyright © 2010 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||||||||||||||