Abstract: SiC surface reconstruction will cause the increase of surface state densities, which can greatly affect the performance of SiC power devices.This paper aims to investigate the (3×3) R30° and (3×3) reconstructed structures on 4H/6H-SiC (0001)-Si terminal and the (3×2) and (2×1) reconstructed structures on 3C-SiC (0001)-Si terminal after S atoms adsorption.The results show that S adsorption can open the reconstruction bonds and that the different reconstructed structures have a tendency to recover to the ideal models.The optimum adsorption rate of (3×3)R30° is 1/2ML and that of (3×3) is 1/3ML.The adsorbed S atoms have a greater impact on the recovery of the (3×3)R30° reconstructed structure than that of (3×3).Additionally,H3 site is the best initial position and 1/6ML is the optimum adsorption rate for (3×2) 3C-SiC reconstructed structures,while B site is the best initial position and 1/2ML is the optimum adsorption rate for (2×1) 3C-SiC reconstructed structures.The surface adsorption energy of 3C-SiC reconstructed structures is smaller and the surface is more stable than that of 4H/6H-SiC.The recovery of 3C-SiC reconstructed structures is more desirable.

Key words: SiC surface reconstruction will cause the increase of surface state densities, which can greatly affect the performance of SiC power devices.This paper aims to investigate the (3×3) R30° and (3×3) reconstructed structures on 4H/6H-SiC (0001)-Si terminal and the (3×2) and (2×1) reconstructed structures on 3C-SiC (0001)-Si terminal after S atoms adsorption.The results show that S adsorption can open the reconstruction bonds and that the different reconstructed structures have a tendency to recover to the ideal models.The optimum adsorption rate of (3×3)R30° is 1/2ML and that of (3×3) is 1/3ML.The adsorbed S atoms have a greater impact on the recovery of the (3×3)R30° reconstructed structure than that of (3×3).Additionally,H3 site is the best initial position and 1/6ML is the optimum adsorption rate for (3×2) 3C-SiC reconstructed structures,while B site is the best initial position and 1/2ML is the optimum adsorption rate for (2×1) 3C-SiC reconstructed structures.The surface adsorption energy of 3C-SiC reconstructed structures is smaller and the surface is more stable than that of 4H/6H-SiC.The recovery of 3C-SiC reconstructed structures is more desirable.