Native point defects and low p-doping efficiency in Mg2(Si,Sn) solid solutions: A hybrid-density functional study

JOURNAL OF ALLOYS AND COMPOUNDS

卷:853

Article

Ryu, Byungki¹  Choi, Eun-Ae²  Park, Sungjin¹  Chung, Jaywan¹  de Boor, Johannes³  Ziolkowski, Pawel³  Muller, Eckhard^3,4  Park, SuDong¹ 

[1] Korea Electrotechnol Res Inst KERI, Energy Convers Res Ctr, Elect Mat Res Div, Chang Won 51543, South Korea

[2] Korea Inst Mat Sci ICIMS, Mat Proc Innovat Res Div, Computat Mat Dept, Chang Won 51508, South Korea

[3] German Aerosp Ctr DLR, Inst Mat Res, D-51147 Cologne, Germany

[4] Justus Liebig Univ, Inst Inorgan & Analyt Chem, D-35392 Giessen, Germany

关键词: Thermoelectric;    Native defects;    Hybrid-DFT;    Conductivity;    Charge compensation;    Doping efficiency;   

DOI  :  10.1016/j.jallcom.2020.157145

来源: Elsevier

【 摘 要 】

We perform hybrid-density functional calculations to investigate the charged defect formation energy of native point defects in Mg2Si, Mg2Sn, and their solid solutions. The band gap correction by hybrid-density functional is found to be critical to determine the charged defect density in these materials. For Mg2Si, Mg interstitials are dominant and provide unintentional n-type conductivity. Additionally, as the Mg vacancies can dominate in Mg-poor Mg2Sn, p-type conductivity is possible for Mg2Sn. However, the existence of low formation energy defects such as Mg-Sn(1+) and I-Mg(2+) in Mg2Sn and their diffusion can cause severe charge compensation of hole carriers resulting in low p-type doping efficiency and thermal degradation. Our results indicate that, in addition to the extrinsic doping strategy, alloying of Mg2Sn with Mg2Si under Mg-poor conditions would be necessary to enhance the p-type conductivity with less charge compensation. (c) 2020 The Authors. Published by Elsevier B.V.

【 授权许可】

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