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セガワ コウジ
SEGAWA KOJI
瀬川 耕司 所属 京都産業大学 理学部 物理科学科 職種 教授 |
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| 言語種別 | 英語 |
| 発行・発表の年月 | 2015/02/17 |
| 形態種別 | 研究論文 |
| 標題 | Ultrafast carrier relaxation through Auger recombination in the topological insulator B i1.5 S b0.5 T e1.7 S e1.3 |
| 執筆形態 | その他 |
| 掲載誌名 | Physical Review B - Condensed Matter and Materials Physics |
| 出版社・発行元 | American Physical Society |
| 巻・号・頁 | 91(8) |
| 著者・共著者 | Yoshito Onishi,Zhi Ren,Kouji Segawa,Wawrzyniec Kaszub,Maciej Lorenc,Yoichi Ando,Koichiro Tanaka |
| 概要 | Ultrafast carrier dynamics have great significance for our understanding of the transport properties of the surface state in topological insulator (TI) materials. We report midinfrared pump-probe measurements on the intrinsic TI material Bi1.5Sb0.5Te1.7Se1.3 and show that the change in photoinduced reflectivity can be decomposed into a fast negative part and a slow positive part. Calculations of the dielectric function made at various carrier temperatures and densities reveal that the fast negative component corresponds to the disappearance of the phase-space filling effect due to hot carriers around the probe energy and the decay component corresponds to the recombination of carriers near the band edge. The ratio of the fast negative component to the slow positive component is larger in the excitations conducted at the higher carrier densities, which suggests that the carrier temperature increases through Auger recombination. A qualitative analysis using rate equations reinforces this assumption, so we conclude that Auger recombination is the main cause of the population relaxation at carrier densities higher than 1018cm-3 and that we determined the Auger coefficient for Bi1.5Sb0.5Te1.7Se1.3 as C=0.4×10-26cm6/s. |
| DOI | 10.1103/PhysRevB.91.085306 |
| ISSN | 1550-235X |
| PermalinkURL | https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84923238242&origin=inward |