Papers by Keyword: MPCVD

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Authors: Chong Mu Lee, Kyung Ha Kim
Abstract: Diamond-like carbon (DLC) films have been deposited by radio frequency plasma enhanced chemical vapour deposition (rf-PECVD) with different Ar-CH4 mixtures. Nanocrystalline diamond films have been deposited by microwave plasma-enhanced chemical vapour deposition (MPCVD), using Ar-H2-CH4 mixtures. X-ray photoelectron spectroscopy (XPS) and nanotribological investigation (by scanning force microscopy) have been used to compare the mechanical properties and structures of these films. Highly orientated and non-orientated microcrystalline diamond films and MPCVD-produced amorphous carbon have also been studied by way of comparison. The diamond films exhibit a linear relationship between roughness and the coefficient of friction. The DLC and amorphous carbon have higher friction coefficients than the best performing diamond film, but may more easily be deposited as smooth coating. Possible applications for these various carbon-based films include microelectromechanical components, for which smooth, hard coatings are required.
Authors: Cheolmun Yim, Do Hoon Shin, Yun Hae Kim, Yasunobu Moriguchi, Riichi Murakami
Abstract: Diamond film was deposited on the pure titanium substrate by CH4-H2 gas mixture using MPCVD method. In order to carboxylate the surface of the diamond film, it was chemically treated in H2SO4:HNO3 (9:1, case 1) stirred at room temperature or in H2SO4:HNO3 (3:1, case 2) stirred at reflux. The oxidized diamond film was successively treated with 0.1M NaOH for 2hours and 0.1M HCl at 363K for 2hours, and then washed by distilled water. The surface of diamond film was observed by scanning electron microscopy (SEM). The diamond film was characterized using Raman spectroscopy and X-ray diffraction (XRD). Carboxylated diamond film was evaluated by Fourier transform infrared spectrometer (FT-IR), Mini secondary ion mass spectrometer (Mini SIMS) and X-ray photoelectron spectroscopy (XPS). In the FT-IR spectrum, the peak at 1640cm -1 was assigned with C=O stretching vibration of carboxylic acid. In the Mini SIMS profile, the peak intensities of mass number 16 (-O-) and 17 (-OH) were increased after the chemical treatment. The XPS results indicated COO- group and C=O group on the surface of diamond film.
Authors: Fu Yuan Xia, Lin Jun Wang, Jian Huang, Ke Tang, Ji Jun Zhang, Wei Min Shi
Abstract: Undoped high quality polycrystalline diamond films were grown by the microwave plasma chemical vapor deposition (MPCVD) method. The effects of hydrogen plasma treatment and vacuum annealing process on the p-type behavior of diamond films were investigated by the Hall effect method. The sheet carrier concentration increased and the sheet resistivity decreased with the treating time of hydrogen plasma and a stable value was achieved finally. After annealing the samples in vacuum at temperature above 600 °C, the sheet carrier concentration dropped dramatically. The origin of this hydrogen terminated p-type conductive layers is also discussed.
Authors: Wen Juan Cheng, Jin Chun Jiang, Yang Zhang, De Zhong Shen, He Sun Zhu
Abstract: Silicon carbon nitride (SiCN) films have been deposited on silicon wafers by microwave plasma chemical vapor deposition (MPCVD). Gas mixture of H2, CH4, N2, and SiH4 was used as precursors, in which the flow rate of N2 was changed. X-ray photoelectron spectroscopy (XPS) and micro-Raman spectroscopy were employed to characterize the composition and bonding structures, while field-emission scanning electron microscopy were used to investigate the microstructure of the films. With increasing the flow rate of N2 from 50 sccm to 300 sccm, the SiCN films changed from amorphous to nanocrystalline. Characteristic current-voltage measurements indicate a low turn-on field of 10.8 V/µm. Field emission current density of 4.5 mA/cm2 has been observed at 20 V/µm.
Authors: Zhi Qin Fan, Hai Feng Ou, Rui Li, Gen Wang Cai, Jun De Zhang
Abstract: Carbon nanotubes(CNTs) films were fabricated by microwave plasma chemical vapor deposition (MPCVD) on stainless steel substrates. In order to study the reason that its emission current weakens, the CNTs films were treated by hydrogen plasma. The research discovered that the hydrogen plasma treatment to the carbon nanotubes films reduced the surface work function of the film and its filed emission current, this mainly due to the etching of hydrogen plasma to sp2 carbon on the surface, it leads emission area to decrease.
Authors: Jung Sheng Chen, Ku En Ting, Hui Ching Wang
Abstract: Diamond-like carbon (DLC) films have attracted great interest due to their outstanding mechanical, biocompatibility, thermal, optical and electrical properties. The DLC films can be produced by microwave plasma chemical vapor deposition (MPCVD) using Argon, methane and hydrogen mixed gases. The film properties depend strongly on the experimental parameters such as substrate temperatures; microwave power, process pressure and hydrogen concentration (H2/Ar+CH4+H2). In this study, the properties of nanomechanics of DLC films with various experimental parameters are firstly discussed which include hardness and Young’s modulus characterizing by depth-sensing nanoindentation technique. The nanoindentation is an excellent method for measuring nanomechanical properties of both bulk and thin films. The probe was conducted using a Berkovich diamond tip. To find the optimized process parameters, the statistical and mathematical response surface methodology (RSM) is used to model and analyze the effect of substrate temperature (T), microwave power (W), process pressure (P) and hydrogen concentration (H) on the properties of nanomechanics of DLC films. The central composite experimental design (CCD) is used to evaluate the interaction parametric effects of multiple experimental variables on process response (hardness and Young’s modulus). The predictive quadratic model proposed herein considering the analysis of variance (ANOVA) are proved to fit and predict values of the hardness and Young’s modulus close to those readings recorded experimentally. The most significant influential factors for maximizing the hardness and Young’s modulus have been identified from the ANOVA table. The RSM technique is demonstrated to be a powerful tool in exploration of the manufacturing parameters space of complex physical process of DLC films deposition by MPCVD.
Authors: Xiang Qin Meng, Wu Jun Fu, Bing Wang, Cheng Tao Yang
Abstract: Nanocrystalline diamond (NCD) films were prepared on polycrystalline aluminum oxide (Al2O3) substrates by microwave plasma chemical vapor deposition (MPCVD) technique using Ar/CH4/CO2 plasma. The main objective is to study the structure and mechanical properties of the NCD films. The NCD films micrograph were examined by scanning electron microscopy (SEM) and atom force microscopy (AFM). The structure and phase composition of the films were analyzed by X-ray diffraction (XRD) and visible Raman spectroscopy. Friction testing machine was used to test the friction coefficient of the films. It was found that the diamond films possess better structure and smooth surface. Compared to Al2O3 substrates, the friction coefficient of the NCD films was smaller and the wear resistance was improved significantly.
Authors: Zhi Qian Wang, Jin Hai Gao, Ning Yao, Bing Lin Zhang
Abstract: Chain-like Carbon Nano-tubes films have been synthesized by microwave plasma enhanced chemical vapor deposition (MWPECVD). The titanium-coated ceramic substrate was placed in a stainless steel reaction chamber of MPCVD system. Prior to deposition, The substrates were grinded with SiO2 powder with Fe dopant . The mixture gas of methane (CH4) and hydrogen (H2) was introduced into the chamber. The flow rates of CH4/H2 were controlled at 14/100 sccm by mass flower, respectively. The total pressure in the chamber was kept at 6.2kPa during the deposition. The microwave power of 1700w, worked at a frequency of 2450Mhz, was applied during deposition. The deposition time was only 1minute. The nano-structure of the deposited films was analyzed by SEM, TEM and Raman spectroscopy. The chain-like nano-tubes randomly distributed on the substrates. The nano-tubes are multi-wall with diameter of about 60 nm. The field electron emission characteristics of the Chain-like Carbon Nano-tubes films were measured under the vacuum of 10-5Pa. The low turn-on field of 0.74V/μm and emission current density of 8.5mA/cm2 at electric field 2.9V//μm were obtained. The mechanism of its field emission properties was also discussed.
Authors: Chang Geng Zhou, Rui Qiu, Jian Lin Ke, Cai Lin Liu, Bing Wang
Abstract: The diamond films deposition experiment is carried out with MPCVD system. Some technology problems are discussed respectively, such as the substrate pretreatment, gases source compositions and deposition temperature. XRD pictures with different peaks illustrated that diamond film has good crystal orientation. A density of film crystal is observed and a thickness uniformity in detected by Scanning Electron Microscopy (SEM). The pureness of the diamond film was measured by Raman spectroscopy. The parameter coincidence rate is 90% based on the 10 prepared samples
Authors: Wen Jing Wang, Xing Yuan Li, Hong Mei Zhang, Xi Feng Ding, Xin Sun
Abstract: This research took CH4 and H2 as the air source and sufficiently utilized the diamond films generated on the Si piece due to the microwave plasma chemical vapor deposition (MPCVD) method. Raman spectrum functioned as the key method to investigate the diamond films in such research. The diamond phase, large graphite monocrystals and the disorderly graphite in the films were related respectively to different Raman characteristic peaks. An analysis and related investigation on the Raman spectrum of the sample revealed the performance parameters of the structure, purity and stress of the diamond films in different concentrations of the air source.
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