Revealing the role of Si vacancy and interface in SiHCl3 dissociation applied in polysilicon

Abstract

In the production of polysilicon, the virous orientations of silicon crystal planes lead to Si vacancies and interfaces formation. However, the impact of these defects on the reaction of SiHCl3 reduction to Si is unclear. In this work, we demonstrated that both Si vacancies and interfaces significantly improve the silicon deposition rate while inhibiting the formation of by-production SiCl4, through Density functional theory calculations. Specifically, the Si vacancy alters the charge distribution on Si (111) surface, leading to an increased concentration of charges on the low-coordination Si atoms and placing the Si vacancy in an electron-deficient state. In addition, the Si vacancy induces charge transfer between surface and subsurface Si atoms, which directly influences the adsorption and activation of reactive species on active sites. These findings endow Si (111)-V surface containing Si vacancy exhibiting the highest activity and selectivity for SiHCl3 reduction to Si.