| Origin of p-type characteristics in a SnSe single crystal | |||||
| 작성자 | 김** | 작성일 | 2018-08-30 | 조회수 | 74 |
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Journal Article published 26 Jun 2017 in Applied Physics Letters volume 110 issue 26 on page 262106
Authors: Ganbat Duvjir, Taewon Min, Trinh Thi Ly, Taehoon Kim, Anh-Tuan Duong, Sunglae Cho, S. H. Rhim, Jaekwang Lee, Jungdae Kim https://doi.org/10.1063/1.4991003 ABSTRACT SnSe single crystals have recently been found to exhibit excellent thermoelectric performance with an extremely high figure of merit (ZT) value of 2.6. Although this high ZT value has attracted considerable attention, the microscopic origin of the p-type characteristics of SnSe is not yet clearly understood. Here, we directly observed and identified intrinsic point defects existing on SnSe via scanning tunneling microscopy (STM) and investigated the effect of defects on the electronic properties using density functional theory (DFT) calculations. Our results demonstrate that the most dominant Sn vacancies move the Fermi energy inside the dispersive valence band and produce extra holes throughout the system. On the other hand, Se vacancies create a nondispersive donor level and generate immobile electrons localized near the vacancy site. Our combined STM/DFT studies show that the p-type characteristics of SnSe originate from extra holes in the dispersive Bloch-like band created by Sn vacancies. We expect that our results provide important information for the development of highly efficient SnSe-based thermoelectric devices. |
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