Seminar & Colloquium
[세미나: 12월 5일(목), 오후 2시 50분] Prof. Yan Li, Osaka University
Title
Influence of light illumination on the dislocation-based plasticity in ZnO&GaN semiconductors
Speaker
Prof. Yan Li, Assistant Professor of school/graduate school of engineering science, Osaka University, Japan
* Biography
Dr. Yan Li is an assistant professor in the school of engineering science, Osaka University, Japan. Yan Li received her Ph.D. from Tsinghua University in 2019. Before joining Osaka University in 2021, she was a post-doctoral fellow at Tsinghua University in 2020 and Nagoya University in 2021. Dr. Li’s research focuses on investigating the room-temperature mechanical properties of inorganic semiconductors and ceramics, with particular focus on the effects of external fields on their behavior.
| Date | Thursday, December 5th, 2024
| Time | 14:50~15:30
| Venue | 33동 125호(WCU 다목적실)
[Abstract]
In conventional understanding, most semiconductors are brittle and exhibit limited plasticity at room temperature. However, the ZnS single crystal was reported to exhibit a compression strain of ~45% in darkness, while the crystal fractured instantly after yielding at a strain of ~2.5% in light [1]. Such a big difference in plasticity highlighted the crucial role of external light fields on the mechanical properties of semiconductors. It was believed that dislocations, the dominant carriers of plasticity in crystals, interact with the photo-excited carriers, thereby influencing the plasticity of materials. In this work, the effects of light on the mechanical responses of ZnO and GaN were studied using nanoindentation technique. Through statistical analysis of the first pop-in events, illumination showed a slight impact on dislocation nucleation. In nanoindentation creep tests, the depth in light was markedly smaller than that in darkness, suggesting the suppression of dislocation behaviors by light. Further TEM observations were performed to understand the effect of light at the dislocation level.
[1] Y. Oshima, A. Nakamura*, K. Matsunaga*, Science 360, (2018) 772–774.
| Host | 최인석 교수(02-880-1712)