中国物理B ›› 2021, Vol. 30 ›› Issue (9): 96806-096806.doi: 10.1088/1674-1056/ac1e22

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Atomic and electronic structures of p-type dopants in 4H-SiC

Lingyan Lu(卢玲燕)1,†, Han Zhang(张涵)2,†, Xiaowei Wu(吴晓维)2, Jing Shi(石晶)1,‡, and Yi-Yang Sun(孙宜阳)2,§   

  1. 1 Department of Physics, Jiangxi Normal University, Nanchang 330022, China;
    2 State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 201899, China
  • 收稿日期:2021-07-07 修回日期:2021-07-26 接受日期:2021-08-17 出版日期:2021-08-19 发布日期:2021-08-30
  • 通讯作者: Jing Shi, Yi-Yang Sun E-mail:sjd865@jxnu.edu.cn;yysun@mail.sic.ac.cn

Atomic and electronic structures of p-type dopants in 4H-SiC

Lingyan Lu(卢玲燕)1,†, Han Zhang(张涵)2,†, Xiaowei Wu(吴晓维)2, Jing Shi(石晶)1,‡, and Yi-Yang Sun(孙宜阳)2,§   

  1. 1 Department of Physics, Jiangxi Normal University, Nanchang 330022, China;
    2 State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 201899, China
  • Received:2021-07-07 Revised:2021-07-26 Accepted:2021-08-17 Online:2021-08-19 Published:2021-08-30
  • Contact: Jing Shi, Yi-Yang Sun E-mail:sjd865@jxnu.edu.cn;yysun@mail.sic.ac.cn

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摘要： Using hybrid density functional calculation, we study the atomic and electronic structures of p-type dopants, B, Al and Ga, in 4H-SiC. For B, depending on the growth condition, it can occupy both Si and C sites. In contrast, Al and Ga on the C sites exhibit too high formation energy to exist in a significant amount. In 4H-SiC, there exist two types of Si sites in wurtzite-like and zincblende-like local coordination, respectively. Our calculations suggest that the dopant atoms have negligible preference occupying the two sites. In neutral charge state, all the dopants exhibit significant distortions from the structure in the negatively charged state. For most cases, our calculations yield three distorted structures, in which the most stable one has the dopant atom displaced along its bond with one of the surrounding equatorial Si or C atoms, lowering the C3v symmetry to Cs symmetry (i.e., a mirror symmetry only). Among the three dopant elements, Al on Si sites exhibits overall the lowest formation energy and the shallowest acceptor level. Nevertheless, it is not a hydrogenic dopant with the acceptor level 0.12 eV above the valence band maximum based on calculation using a 400-atom supercell. Its corresponding defect state exhibits apparent localization along the [0001] direction, but it is relatively delocalized in the (0001) plane.

关键词: wide band gap semiconductors, p-type doping, SiC, density functional theory

Abstract: Using hybrid density functional calculation, we study the atomic and electronic structures of p-type dopants, B, Al and Ga, in 4H-SiC. For B, depending on the growth condition, it can occupy both Si and C sites. In contrast, Al and Ga on the C sites exhibit too high formation energy to exist in a significant amount. In 4H-SiC, there exist two types of Si sites in wurtzite-like and zincblende-like local coordination, respectively. Our calculations suggest that the dopant atoms have negligible preference occupying the two sites. In neutral charge state, all the dopants exhibit significant distortions from the structure in the negatively charged state. For most cases, our calculations yield three distorted structures, in which the most stable one has the dopant atom displaced along its bond with one of the surrounding equatorial Si or C atoms, lowering the C3v symmetry to Cs symmetry (i.e., a mirror symmetry only). Among the three dopant elements, Al on Si sites exhibits overall the lowest formation energy and the shallowest acceptor level. Nevertheless, it is not a hydrogenic dopant with the acceptor level 0.12 eV above the valence band maximum based on calculation using a 400-atom supercell. Its corresponding defect state exhibits apparent localization along the [0001] direction, but it is relatively delocalized in the (0001) plane.

Key words: wide band gap semiconductors, p-type doping, SiC, density functional theory

中图分类号:  (Defects and impurities: doping, implantation, distribution, concentration, etc.)

  • 68.55.Ln
71.15.Mb (Density functional theory, local density approximation, gradient and other corrections)