Native point defects and low $p$-doping efficiency in $Mg_2 (Si,Sn)$ solid solutions: A hybrid-density functional study
| Autor: | Ryu, Byungki, Choi, Eun-Ae, Park, Sungjin, Chung, Jaywan, de Boor, Johannes, Ziolkowski, Pawel, Müller, Eckhard, Park, SuDong |
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| Rok vydání: | 2020 |
| Předmět: | |
| Zdroj: | Journal of Alloys and Compounds 853, 157145 (2021) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1016/j.jallcom.2020.157145 |
| Popis: | 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. Comment: Main: 17 pages (including title, abstract, main, references, figure captions. 4 figures). This manuscript is accepted for publication in JALCOM. The article will be published as Gold Open Access |
| Databáze: | arXiv |
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