Papers by Keyword: Microwave Plasma

Abstract: The aim of this work is to use x-ray diffraction (XRD) technique to analyze ZnO particles prepared by the reaction between the zinc vapor and oxygen within microwave plasma. The microwave plasma was created by the interaction between the 1200-W 2.45-GHz microwave, the conductive material, and the argon-oxygen gas mixture. Due to the high effective temperature of the plasma, it was thermodynamically and kinetically possible to generate zinc vapor from the solid zinc and then reacted with the oxygen in the gas mixture to form ZnO particles. The synthesis of ZnO in the microwave plasma has been done for 10 to 15 minutes. The XRD results show that the synthesized ZnO samples have wurtzite structure. Moreover, the increasing of synthesis time from 10 to 15 minutes affects the lattice constants, the crystallite size, and the magnitude of strain in ZnO crystals.

Abstract: This work aims to develop a low pressure microwave plasma deposition system to coat carbon thin film on silicon substrate. The system use a commercial microwave oven as a microwave source to get plasma discharge. The vacuum pressure was achieved by two stage rotary vane vacuum pump which is capable to reach ultimate pressure at 2×10^-1 Pa under borosilicate chamber glass. The carbon thin films was successfully deposited on silicon substrate by pure acetylene plasma with gas flow rate 30 ml/min at total operating pressure of -70 cmHg reading by analog dial vacuum gauge, using microwave power at 1,200 Watts and deposit time at 150 seconds. Raman analysis showed peak at around 1336.20 cm^-1 (D-peak) and 1611.87 cm^-1 (G-peak), by utilizing I_D and I_G can be determined that there are 43.22% of sp³ contained in deposited film. Energy Dispersive X-Ray analysis indicated that the deposited thin film compose of carbon atoms 82.00 at% and silicon atoms 18.00 at%. The morphology and the thickness of the film was investigated by scanning electron microscope and atomic force microscope, respectively.

Abstract: This paper reports about results describing the mechanism of oxidation-reduction reactions occurring in the microwave plasma interaction with organic compounds solutions. Air and argon were used as the plasma gases in the experiments on disrupture of aqueous liquid organic compounds. Application of inversible redox indicator of methylene blue (MB) showed that disrupture of organic substances in microwave plasma was based on redox reactions. It was found that MB highest efficiency in the solution took place when air plasma-supporting gas was used.

Abstract: NH₃ was synthesized from H₂ and N₂ under normal temperature and pressure by microwave plasma. The effects of microwave input power, ratio of H₂/N₂, the amount of total material gas concentration and catalyst on the synthetic reaction were studied. The volume fraction of NH₃ can reach 0.58% under the optimal condition.

Abstract: Hydrogenated amorphous carbon (a-C:H) films were prepared by microwave plasma chemical vapor deposition (MW-PCVD) technique with a mixture of acetylene and hydrogen. The morphology of three-phase a-C:H films, such as graphite-like, diamond-like and polymer-like were modulated by microwave power, deposition pressure, and flow ratios. Meanwhile, annealing does not seem to change the surface morphology or the film structure. The phase transitions are not found during the different annealing temperatures, showing that a-C:H films have a good thermal stability.

Abstract: Titanium implant surfaces should ideally be designed to support the subsequent clinical application. Therefore temporarily used implants have to fulfill both the mechanical stabilization of the bone stock and furthermore in trauma surgery the disintegration into the bone because the implant should be removed after fracture healing. The anti-adhesive plasma-fluorocarbon-polymer (PFP) films were synthesized using two different low-pressure plasma sources, the 2.45 GHz microwave (mw) and the 13.56 MHz capacitively coupled radio-frequency (rf) discharge in a mixture of the precursor octafluoropropane (C₃F₈) and hydrogen (H₂). The film properties were characterized using X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, water contact angle measurements, and abrasive strength tests. Cell adhesion and spreading of human osteoblasts were clearly reduced on these PFP surfaces. First in vivo data on the biocompatibility of the PFP films deposited in the rf-discharge demonstrate that the local inflammatory tissue response for PFP coating was comparable to controls, while a PFP coating deposited in mw plasma induced stronger tissue reactions.

Abstract: In the present study, we fabricated the CNT-porous ZnO composite by Microwave Plasma Jet Chemical Vapor Deposition (MPJCVD) System. The morphology and characteristics of the CNT-porous ZnO were examined by SEM, EDS and Raman spectrometer. Finally, a few carbon content was found to exist within the CNT-porous ZnO nanocomposite.

Abstract: Microwave plasma techniques offered many advantages over conventional fabricating methods. However, few studies have used microwave plasma energy to sinter traditional ceramics. Thus, the aim of this work is microwave plasma Jet sintering system (MPJSS) and simulate analyze the electric field of ZnO films on Si (100) substrates. Ansoft HFSS consists of MPJSS modules for the calculation of ZnO films electromagnetic field. Sinter of ZnO films occurs at approximately N₂ with a 10 sccm gas flow rate for a process pressure of 35 Torr and several power of 300W, 600W, 900W and 1200W applied power. Optical emission spectroscopic (OES) studies of N₂ microwave plasmas, X-ray diffraction (XRD), Micro-Raman, and FESEM spectrometry were used to characterize the produced ZnO films. The results of XRD and Micro-Raman showed that the synthesized ZnO films had a high crystalline wurzite structure. The Zn₂SiO₄ peaks reveal an increase of the crystals dimensions with the increase of the E-field. Intensity of diffraction peak of ZnO films increases with increasing microwave powers in MPJSS.

Abstract: In this paper, carbon spheres were synthesized by CVD method. These carbon spheres exhibit diameters of about 200 nm. Thermal gravimetric analysis indicated the good stability in high temperature of the carbon spheres. The products were treated by microwave plasma and high temperature vacuum heat treatments respectively. The products were characterized by X-ray diffraction, Raman spectroscopy and Field Emission Scanning Electron Microscope. The study indicated that the original products, with perfect morphology and low graphitization degree, were converted to crystal. The different techniques were considered for the influence on the graphitization degree.

Abstract: Perfluorocarbons have been widely used in the semiconductor industry. As highly potent global warming gases, they have extremely long atmospheric lifetime and intensive absorption ability of infrared radiation. Naturally, the abatement of PFCs becomes a critical environmental issue. In this paper, an effort is made to review the development of microwave plasma technology for the control of PFCs. Relevant studies indicate that microwave plasma has the advantage of high electron temperature and high electron density which is of great potential to PFCs abatement. Low pressure microwave plasma may interfere with the normal operation of semiconductor manufacturing processes. At atmospheric pressure, microwave plasmas exhibit high react performance with PFCs. The atmospheric pressure microwave plasma combined with catalyst can reduce the microwave power and increase the destruction and removal efficiency and energy efficiency. The combination technology has a good potential to be used as an integrated technology for abating PFCs from complicated gas streams of semiconductor manufacturing processes.