A steady-state,direct-current high-pressure CH_(4)-H_(2) glow discharge in a cup-shaped cathode parallel to anode configuration is investigated by using their V–I characteristics and CCD images.The discharges display...A steady-state,direct-current high-pressure CH_(4)-H_(2) glow discharge in a cup-shaped cathode parallel to anode configuration is investigated by using their V–I characteristics and CCD images.The discharges display an abnormal glow feature,and an expansion of a negative glow is observed on the cathode sidewall with the increasing discharge current.There exists a dependence of voltage on gas pressure for different fixed currents.The voltage decreases with gas pressure initially,and then increases conversely,which is correlated with the glow states of the cathode sidewall.This study exhibits a self-adjusting characterization for plasmas in cathode fall,which is important for maintaining steady-state,abnormal glow discharge in a relatively high pressure range.展开更多
Growth of SiC nanowires in plasma-assisted hot filament chemical-vapor-deposition by using hexamethyldisiloxane （HMDSO） as the gas source is reported. The SiC nanowires （SIC NWs） grew on Au-coated silicon substrat...Growth of SiC nanowires in plasma-assisted hot filament chemical-vapor-deposition by using hexamethyldisiloxane （HMDSO） as the gas source is reported. The SiC nanowires （SIC NWs） grew on Au-coated silicon substrate with core-shell structure, where the core consisted of polycrystalline SiC grains and the shell exhibited amorphous structure. The featured structures such as cones, polyhedrons, ball-liked particles were observed in the case without plasma assistance. The underlying mechanism for the growth of nanostructures was also discussed. The high chemical activity induced by the plasma process plays an important role in using monomer to generate nanostructure.展开更多
Electron cyclotron resonance radio frequency （ECR-rf） hybrid krypton-diluted oxygen plasmas were used to pattern the surfaces of diamond films with the assistance of a physical mask, while optical emission spectrosc...Electron cyclotron resonance radio frequency （ECR-rf） hybrid krypton-diluted oxygen plasmas were used to pattern the surfaces of diamond films with the assistance of a physical mask, while optical emission spectroscopy was employed to characterize the plasma. It was found that with krypton dilution the etching rate decreased, and also the aspect ratios of nanotips formed in micro-holes were significantly modified. The oxygen atomic densities were estimated by oxygen atom optical emission and argon actinometry. Under a microwave power of 300 W and rf bias of-300 V, the absolute density of ground-state oxygen atoms decreased from 1.3×10^12 cm^-3 to 1.4×10^11 cm^-3 as the krypton dilution ratio increased to 80%, accompanied by the decrease in the plasma excitation temperature. It is concluded that oxygen atoms play a dominant role in diamond etching. The relative variations in the horizontal and vertical etching rates induced by the addition of krypton are attributed to the observations of thicker nanotips at a high krypton dilution ratio.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 11075158the Fund for Fostering Talents in Basic Science of the National Natural Science Foundation of China(No J1103207)。
文摘A steady-state,direct-current high-pressure CH_(4)-H_(2) glow discharge in a cup-shaped cathode parallel to anode configuration is investigated by using their V–I characteristics and CCD images.The discharges display an abnormal glow feature,and an expansion of a negative glow is observed on the cathode sidewall with the increasing discharge current.There exists a dependence of voltage on gas pressure for different fixed currents.The voltage decreases with gas pressure initially,and then increases conversely,which is correlated with the glow states of the cathode sidewall.This study exhibits a self-adjusting characterization for plasmas in cathode fall,which is important for maintaining steady-state,abnormal glow discharge in a relatively high pressure range.
基金supported by National Natural Science Foundation of China (No.10635010)the Key National Basic Research Program of China (No.2008CB717800)
文摘Growth of SiC nanowires in plasma-assisted hot filament chemical-vapor-deposition by using hexamethyldisiloxane （HMDSO） as the gas source is reported. The SiC nanowires （SIC NWs） grew on Au-coated silicon substrate with core-shell structure, where the core consisted of polycrystalline SiC grains and the shell exhibited amorphous structure. The featured structures such as cones, polyhedrons, ball-liked particles were observed in the case without plasma assistance. The underlying mechanism for the growth of nanostructures was also discussed. The high chemical activity induced by the plasma process plays an important role in using monomer to generate nanostructure.
基金supported by National Natural Science Foundation of China (No. 10635010)National Basic Research Program of China (No. 2008CB717800)
文摘Electron cyclotron resonance radio frequency （ECR-rf） hybrid krypton-diluted oxygen plasmas were used to pattern the surfaces of diamond films with the assistance of a physical mask, while optical emission spectroscopy was employed to characterize the plasma. It was found that with krypton dilution the etching rate decreased, and also the aspect ratios of nanotips formed in micro-holes were significantly modified. The oxygen atomic densities were estimated by oxygen atom optical emission and argon actinometry. Under a microwave power of 300 W and rf bias of-300 V, the absolute density of ground-state oxygen atoms decreased from 1.3×10^12 cm^-3 to 1.4×10^11 cm^-3 as the krypton dilution ratio increased to 80%, accompanied by the decrease in the plasma excitation temperature. It is concluded that oxygen atoms play a dominant role in diamond etching. The relative variations in the horizontal and vertical etching rates induced by the addition of krypton are attributed to the observations of thicker nanotips at a high krypton dilution ratio.
