arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2003.08886cond-mat.mtrl-sci
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$Mg_2 (Si,Sn)$固溶体中的本征点缺陷和低$p$掺杂效率:混合密度泛函研究

Native point defects and low $p$-doping efficiency in $Mg_2 (Si,Sn)$ solid solutions: A hybrid-density functional study

Byungki Ryu, Eun-Ae Choi, Sungjin Park, Jaywan Chung, Johannes de Boor, Pawel Ziolkowski, Eckhard Müller, SuDong Park

摘要:

我们进行混合密度泛函计算,调查带电的缺陷形成能量的原生点缺陷的$Mg_2 Si$,$Mg_2 Sn$,和它们的固溶体。通过混合密度泛函的带隙校正被发现是至关重要的,以确定在这些材料中的带电缺陷密度。对于$Mg_2 Si$,$Mg$材料占主导地位,并提供无意的$n$型导电性。另外,由于$Mg$空位可以在$Mg$贫乏的$Mg_2 Sn$中占主导地位,因此对于$Mg_2 Sn$,$p$型导电性是可能的.然而,在$Mg_2 Sn$中存在低形成能缺陷如$Mg_{Sn}^{1+}$和$I_{Mg}^{2+}$及其扩散可引起空穴载流子的严重电荷补偿,导致低的$p$型掺杂效率和热退化。我们的研究结果表明,除了非本征掺杂策略,合金化的$Mg_2 Si$与$Mg_2 Sn$下$Mg$ -穷人的条件将是必要的,以提高$p$型导电性与较少的电荷补偿。

英文摘要:

We perform hybrid-density functional calculations to investigate the charged defect formation energy of native point defects in $Mg_2 Si$, $Mg_2 Sn$, 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 $Mg_2 Si$, $Mg$ interstitials are dominant and provide unintentional $n$-type conductivity. Additionally, as the $Mg$ vacancies can dominate in $Mg$-poor $Mg_2 Sn$, $p$-type conductivity is possible for $Mg_2 Sn$. However, the existence of low formation energy defects such as $Mg_{Sn}^{1+}$ and $I_{Mg}^{2+}$ in $Mg_2 Sn$ 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 $Mg_2 Si$ with $Mg_2 Sn$ under $Mg$-poor conditions would be necessary to enhance the $p$-type conductivity with less charge compensation.

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