Abstract: According to the experimental condition, we projected three possible paths a, b, c of the reaction between SiHCl₃ and H₂ and path d of SiHCl₃ decomposition in gas phase. The substrate silicon-participating reactions that include SiHCl₃-H₂-Si, SiHCl₃-H₂-Si₂, SiHCl₃-H₂-Si₉-H₁₂ were also discussed and the substrate silicon is simulated by using clusters of Si, Si₂, Si₉H₁₂ respectively. The geometries, vibrational frequencies and energies of every stable point of the system were calculated by using Gaussian 98 program at B3LYP/6-311G^* level. It is shown that the decomposition paths d and c of the reaction between SiHCl₃ and H₂ can be considered as the competing reaction in gas phase, but silicon atoms were not formed. So we consider that single crystalline silicon can deposit on the substrate silicon only under the condition of reaction between SiHCl₃-H₂ and the substrate silicon.

Key words: Density Functional Theory, Transition state, Reaction mechanism, Rate constant