The initial oxidation of the 4H-SiC (0001) surface with C-related point defects: Insight by first-principles calculations

Shengsheng Wei, Zhipeng Yin, Jiao Bai, Weiwei Xie, Fuwen Qin, Yan Su, Dejun Wang

APPLIED SURFACE SCIENCE(2023)

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摘要
The initial oxidation of 4H-SiC (0001) surfaces with C-related point defects (SurfCD) is studied by using first -principles coupled with thermodynamics calculations to gain deeper insights into the effects of C-related point defects on the formation of SiO2 and SiO2/SiC interface. Three types of SurfCD, including a surface with C interstitial defect (SurfCi), a surface with antisite defect (SurfCsi) and a surface with C vacancy (SurfVc) are considered. The initial oxidation of SurfCD commences on the chemisorption of oxygen atoms at the bridge sites between the Si atoms adjacent to the C-related point defects. As the oxygen coverage increased, the effects of C-related point defects on the adsorption sites and energies of oxygen atoms, the diffusion of oxygen atoms and the interfacial lattice strain are elucidated. The thermodynamic diagrams of O/4H-SiC structures are performed to investigate the stability of surface during the actual oxidation conditions for SurfCi, SurfCsi and SurfVc. Ther-modynamically stable intermediate structures are observed on these surfaces during the initial formation of SiO2, the 1 ML structures are the most stable; the Si dangling bonds, Si-O-C structure and C-clusters are observed in the 1 ML structures. Moreover, the evolution mechanisms and electronic properties of the defects are further investigated.
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关键词
Initial oxidation,4H-SiC surface,First-principles,Thermodynamics,Defects evolution
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