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Lu X.,Guizhou University | Qin Y.,Guizhou University | Zhao C.,Guizhou University | Ning J.,Guizhou University | And 3 more authors.
Zhenkong Kexue yu Jishu Xuebao/Journal of Vacuum Science and Technology | Year: 2011

The etching of hydrocarbon films by low energy hydrogen radicals in the nuclear fusion reactor was simulated, based on molecular dynamics, to understand the interaction of the plasma and the carbon-based materials. In the simulation, the reactive empirical bond order (REBO) potential was used to describe the interaction in the C-H system, and Berendsen thermostat scheme was employed in temperature control. The influence of the impinging H atoms with energies of 0.3, 1, 5 and 10 eV, respectively, on the etching rate of the hydrocarbon films was evaluated. The simulated results show that the incident energy strongly affects the etching rates of H and C. For instance, as the incident energy increases, the adsorption rate of H, as well as the etching rates of H and C increase. Moreover, at a given incident energy, H atoms outperform C atoms in etching. The hydrocarbon, formed by the impinging H atoms with energy greater than 1 eV and surface C atoms, can be easily desorbed by H bombardment, resulting in etching of carbon. And the chemical enhanced physical sputtering accounts for the etching of carbon. Source


Zhao C.,Guizhou University | Qin Y.,Guizhou University | Lu X.,Guizhou University | Ning J.,Guizhou University | And 3 more authors.
Zhenkong Kexue yu Jishu Xuebao/Journal of Vacuum Science and Technology | Year: 2011

The impacts of the incident energy of SiF 2 molecules on the SiC surface were simulated, based on molecular dynamics. The energy variations of the particle, impinging in the direction normal to the surface of the SiC films, were 0.3, 1,5, 10, and 25 eV. The simulated results show that the decomposition rate of SiF 2 significantly affects the deposition rates of both F and Si atoms. Moreover, the deposited F and Si atoms form thin Si xF y films. As the incident energy increases, the film thickness firstly increases, and then decreases with an increased density of Si-Si bond. Phase transitions between the two major phases of the SiF x (x=1~4): SiF 2 and SiF was observed. The SiF 2 changed into the SiF phase with an increase of the incident energy. Source


Qin Y.,Guizhou University | Lv X.,Guizhou University | Zhao C.,Guizhou University | Ning J.,Guizhou University | And 4 more authors.
Zhenkong Kexue yu Jishu Xuebao/Journal of Vacuum Science and Technology | Year: 2011

The interaction of low energy CH radicals and the hydrocarbon films was simulated, based on the reactive empirical band order function and molecular dynamics to understand the possible mechanisms of CH re-deposition in fusion. The CH energy ranges from 0.3 eV to 10 eV. The impact of the variations in CH energy on deposition rates of C and H atoms on substrates of hydrocarbon films was analyzed. The simulated results show that the incident energy of the CH strongly affects the deposition rates, the carbon orbital and stoichiometries of the hydrocarbon. For example, as the energy increases, the deposition rates of both C and H increase. And at an energy greater than the dissociation energy of CH, the deposition rate of H atoms was found to be less than that of C atoms with the same energy. Moreover, as the energy increases, the hydrocarbon film grows with increasing density of Csp 2, especially on the surface. The Csp 3 dominated the films, coexisting with Csp 2, but without Csp 1. We found that the hydrocarbon films mainly consist of CH and CH 2. Source


Ning J.-P.,Guizhou University | Lu X.-D.,Guizhou University | Zhao C.-L.,Guizhou University | Qin Y.-M.,Guizhou University | And 4 more authors.
Wuli Xuebao/Acta Physica Sinica | Year: 2010

Molecular dynamics method was employed to investigate the effects of the reaction layer formed near the surface region on CF3 + etching of Si at different temperatures. The simulation results show that the coverages of F and C are sensitive to the surface temperature. With increasing temperature, the physical etching is enhanced, while the chemical etching is weakened. It is found that with increasing surface temperature, the etching rate of Si increases. As to the etching products, the yields of SiF and SiF2 increase with temperature, whereas the yield of SiF3 is not sensitive to the surface temperature. And the increase of the etching yield is mainly due to the increased desorption of SiF and SiF2. The comparison shows that the reactive layer plays an important part in the subsequeat impacting, which enhances the etching rate of Si and weakens the chemical etching intensity. © 2010 Chin.Phys.Soc. Source


Tian S.,Key Laboratory of Radiation Physics and Technology Ministry of Education | He P.,Guizhou University | Zhang J.,Sichuan University | Pan Y.,Southwestern Institute of Physics | Gou F.,Key Laboratory of Radiation Physics and Technology Ministry of Education
Zhenkong Kexue yu Jishu Xuebao/Journal of Vacuum Science and Technology | Year: 2013

The interaction of the impinging C+ ion beam and the fusion material W was modeled and simulated, based on molecular dynamics, to understand the possible mechanisms responsible for the carbon deposition and carbon ion sputtering of W surface in fusion. The impacts of the interaction conditions, including the incident C+ energy and exposure, on the interaction were simulated. The simulated results show that the carbon atom exists mainly in sp3 state on W surfaces, and that the energy of incident C+ strongly affects the deposition and sputtering rates. For example, as the energy increases, the deposition rate of C varies in a decrease-increase mode; whereas the sputtering rate changes in an increase-decrease mode. At an energy of 50 eV and an exposure of 3.11×1016 cm-2, a thin carbon membrane forms on W surface, at an energy of 150 eV and 250 eV, carbon atoms are implanted in top layers of W, no carbon membrane can be observed. As the energy increases, the peaks of the depth profiles of C-W and C-C bonds move deeper inside W, with an increasingly thicker layer of C-W bond and a thickness unchanged layer of C-C bond. The sputtering of W, rarely occurs though, may seriously damage the lattice. Source

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