Papers by Keyword: CVD

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Authors: Fu Jun Sun, Chun Sheng Shi, En Zuo Liu, Chun Nian He, Nai Qin Zhao
Abstract: The emphasis of this study was in-situ synthesis of carbon nanotubes (CNTs) on Mg matrix at 480°C. The process involves homogeneous deposition of Co catalyst onto Mg by deposition-precipitation route with low Co content (1.0 wt.%) and in situ synthesis of CNTs by chemical vapor deposition. The morphologies and microstructure of the as-obtained CNTs/Mg composite powders was characterized by SEM, TEM, Raman spectrum, and XRD. The results indicated that CNTs were well graphitized and uniformly distributed on the surface of Mg powders, which would be beneficial to the mechanical property of CNTs/Mg composites.
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Authors: Christopher Locke, G. Kravchenko, P. Waters, J. D. Reddy, K. Du, A.A. Volinsky, Christopher L. Frewin, Stephen E. Saddow
Abstract: Single crystal 3C-SiC films were grown on (100) and (111) Si substrate orientations in order to study the resulting mechanical properties of this material. In addition, poly-crystalline 3C-SiC was also grown on (100)Si so that a comparison with monocrystaline 3C-SiC, also grown on (100)Si, could be made. The mechanical properties of single crystal and polycrystalline 3C-SiC films grown on Si substrates were measured by means of nanoindentation using a Berkovich diamond tip. These results indicate that polycrystalline SiC thin films are attractive for MEMS applications when compared with the single crystal 3C-SiC, which is promising since growing single crystal 3C-SiC films is more challenging. MEMS cantilevers and membranes fabricated from a 2 µm thick single crystal 3C-SiC grown on (100)Si under similar conditions resulted in a small degree of bow with only 9 µm of deflection for a cantilever of 700 µm length with an estimated tensile film stress of 300 MPa. Single crystal 3C-SiC films on (111)Si substrates have the highest elastic and plastic properties, although due to high residual stress they tend to crack and delaminate.
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Authors: Anne Henry, Xun Li, Henrik Jacobson, Sven Andersson, Alexandre Boulle, Didier Chaussende, Erik Janzén
Abstract: The growth of 3C-SiC on hexagonal polytype is addressed and a brief review is given for various growth techniques. The Chemical Vapor Deposition is shown as a suitable technique to grow single domain 3C epilayers on 4H-SiC substrate and a 12.5 µm thick layer is demonstrated; even thicker layers have been obtained. Various characterization techniques including optical microscopy, X-ray techniques and photoluminescence are compared for the evaluation of the crystal quality and purity of the layers.
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Authors: Jean Lorenzzi, Romain Esteve, Nikoletta Jegenyes, Sergey A. Reshanov, Adolf Schöner, Gabriel Ferro
Abstract: In this work we report on the growth and preparation of 3C-SiC(111) material for metal-oxide-semiconductor (MOS) application. In order to achieve reasonable material quality to prepare MOS capacitors several and crucial steps are needed: 1) heteroepitaxial growth of high quality 3C-SiC(111) layer by vapour-liquid-solid mechanism on 6H-SiC(0001) substrate, 2) surface polishing, 3) homoepitaxial re-growth by chemical vapour deposition and 4) use of an advanced oxidation process combining plasma enhanced chemical vapour deposition (PECVD) SiO2 and short post-oxidation steps in wet oxygen. Combining all these processes the interface traps density (Dit)can be drastically decreased down to 1.2  1010 eV-1cm-2 at 0.63 eV below the conduction band. To our knowledge, these values are the best ever reported for SiC material in general and 3C-SiC in particular.
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Authors: Kazukuni Hara, Masami Naito, Hiroaki Fujibayashi, Atsuya Akiba, Yuuichi Takeuchi, Olga Milikofu, Tomomi Kozu
Abstract: In this report we were able to successfully identify and localize in 3D 3C and 6H foreign polytypes and stress in the embedded epilayer by high resolution 3D Raman spectroscopy, that were otherwise invisible under the microscope or SEM, in non-contact and non-destructive way. Stripe patterned deep trenches with aspect ratio about 2 (depth=3.0μm; width=1.5μm) were formed on 4H-SiC substrate by ICP. The epitaxial layer was embedded in these trenches by SiC CVD. Poly type defects and stress in the embedded epilayer were mapped by curve-fitting of spectra obtained from Raman measurement of the embedded SiC epilayer. The location of the foreign polytypes and the stress inside the stripe pattern allows speculating on the origin of the defects and correlating it to the manufacturing process.
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Authors: Véronique Soulière, Davy Carole, Massimo Camarda, Judith Woerle, Ulrike Grossner, Olivier Dezellus, Gabriel Ferro
Abstract: The aim of this study was to find conditions allowing the "natural" formation of a regular and controllable step bunched morphology on a 4H-SiC seed without the need of any SiC deposition. This was performed by melting a bulk piece of Si on a 4°off 4H seed in the temperature range of 1500 - 1600°C, for 15 min. After etching the remaining Si, the 4H surface was found to be successfully highly step bunched with steps very parallel and regular. A mechanism of dissolution-precipitation was proposed, which could occur both on a short (step to step) and long (centre to periphery) range. This process is kinetically limited at low temperature (1500-1550°C) and considered to be close to the equilibrium at 1600°C.
163
Authors: Chien Chong Chen, Chun Jui Li, Ke An Lin, Tun Hao Hsu, Shu Heng Wang
Abstract: A green process to prepare the hydrophobic and transparent CNT-based surface was developed without using any toxic chemicals, solvents or gases. CNT brush (CNT-b) powder, which was prepared by the repeated CVD, was the main material to prepare the desired surface. An adhesive layer of ethyl cellulose (EC) was spin coated on the glass substrate, where EC formed a networked porous microstructure. A low concentration CNT-b suspension was obtained by sonication of the mixture of CNT-b powders, sodium dodecylbenzenesulfonate (SDBS) and deionized water. To obtain the stabilized CNT-b suspension, it was found that 40 min of sonication time and SDBS/CNT-b weight ratio being 0.1 were required. The target surface was then prepared by spin coating CNT-b suspension on the EC coated glass. The contact angle of the prepared surface was around 120o and the optical transmittance was around 93% for the visible light. Either increasing the number of spin coatings or increasing the concentration of CNT-b suspension could slightly increase the contact angle to around 130o but the optical transmittance significantly reduce to about 75%, leading to a semi-transparent sample.
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Authors: Jin Hua Zheng, Ying Chen
Abstract: In this study a method to deposit a-Si:H-DLC film at room temperature has been explored by CVD. The interface structure of a-Si:H-DLC film and the compositions of DLC film were studied, the adhesion strength of DLC film deposited directly on metal substrates was very poor, there was an almost complete crack at interface between DLC film and metal substrates, the local shedding could also be observed on surface of DLC film. After inserting a-Si:H intermediate material into the interface, the adhesion strength of a-Si:H-DLC film was improved well, the a-Si:H intermediate layer with about 0.2μm thickness was formed, and was very impact. In addition the structures of DLC film mainly were graphite structure with SP2 bonding, and contain a certain amount of diamond structure with SP3 bonding. Load capacity of a-Si:H-DLC film deposited on the metal substrates was also evaluated, as the contact stress (Hertz stress) was less than 544MPa for the film with 1μm-thickness, the failure life was up to 100 million cycles or more by using “ball- on- disk” wear testing machine, therefore it could be used in practice. Changes in load had little effect on friction coefficient.
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Authors: Isabel P.P. Cansado, Paulo A.M. Mourão, Manuela M.L. Ribeiro Carrott, Peter J.M. Carrott
Abstract: A carbon molecular sieve for the purification of a gas mixtures containing O2, N2 and CO2, CH4 was produced from a waste granulated PET by means of a single carbonisation step at 973 K. Activated carbon materials presenting good adsorption capacity and some selectivity for O2/N2 and CO2/CH4 were prepared from granulated PET and cork oak with pore mouth narrowing using CVD from benzene. The diffusion coefficients of O2, N2, CO2 and CH4 in these materials were calculated and are comparable to published values determined on Takeda 3A and on a carbon molecular sieve prepared from PET textile fibres by means of carbonisation and subsequent CVD with benzene. However, the selectivities were not quite as good as those given by Takeda 3A. However, taking into account that this is a first attempt at producing CMS from PET, the results are encouraging, and it is to be expected that further development of the experimental procedure will result in new materials with improved performance.
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Authors: Jin Zhang, Qi Xue, Xiao Wei Cheng, Chun Mei Zhang, Song Xia Li
Abstract: The TiC/Ti(CN)/TiN multilayer coatings were deposited on 42CrMo steel by chemical vapor deposition (CVD) method. The fracture morphology,structure,microhardness and adhesion of the coatings were analyzed. The immersion test in simulant solution with H2S,CO2 at 100°C and electrochemistry test in 20wt% H2SO4 at room temperture were applied to investigate the corrosion resistance of the multilayer films.The results reveal that the multilayer coatings can offer 42CrMo steel higher corrosion resistance,especially the immersion corrosion test.The corrosion rate of the samples coated with CVD multilayer films is reduced more 70 times than that of the uncoated and samples by quenching-polishing-quenching (QPQ) treat.
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