S吸附对SiC表面不同重构结构的影响

Effect of S Adsorption on Different Reconstructed Structures of SiC Surface

SiC表面重构的发生会引起表面态密度增加,极大地影响SiC功率器件的性能。本文对4H/6H-SiC(0001)-Si端的(3^(1/2)×3^(1/2))R30°和(3×3)重构结构及3C-SiC(0001)-Si端的(3×2)和(2×1)重构结构分别进行了S原子的吸附研究。结果表明:吸附S原子可以打开表面重构键,不同重构结构均有向体结构恢复的趋势。(3^(1/2)×3^(1/2))R30°和(3×3)重构的最佳吸附率分别是1/2ML和1/3ML,S吸附对(3^(1/2)×3^(1/2))R30°重构的作用更大。(3×2)重构表面在1/6ML下的H3位吸附、(2×1)重构表面在1/2ML下的B位吸附时吸附能最低。S钝化后,3C-SiC比4H/6H-SiC体系表面吸附能小,更稳定,重构结构恢复更理想。

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^（1/2） × 3^（1/2）） 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^（1/2） × 3^（1/2）） 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^（1/2） × 3^（1/2））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-Si C. The recovery of 3C-SiC reconstructed structures is more desirable.