报告题目：Optical properties of Ge_1-ySn_y direct bandgap semiconductors

报告人：Prof. Mee-Yi Ryu, 韩国江原国立大学

邀请人：陈长清

报告时间：2016年11月7日星期一下午3:00

报告地点：武汉光电国家实验室A302

摘要:

Group-IV materials such as Ge, GeSn, and GeSiSn alloys grown on Si substrate has attracted recently a lot of interest due to the applications of optoelectronic devices operating in near- and mid-infrared, and the compatibility with the complementary metal–oxide–semiconductor (CMOS) process. Toward this end, a significant breakthrough has been made on device quality Ge1-ySny material growth and optical and electrical characterization has been reported by several research groups. As a result of intensive effort, Si photonics has achieved significant progress through the development of Si-based various devices such as Ge/Ge1-ySny/Ge light emitting diode, Ge1-ySny/Si p-i-n diodes, Ge/Si p-n-n laser diodes, and Ge1-ySny/Si photodetectors. Furthermore, the lasing in direct-bandgap GeSn alloy grown on Ge-buffered Si was demonstrated at low temperatures and relatively high optical pumping, and the indirect-to-direct bandgap transition was found at ~9% Sn for fully relaxed samples. In spite of the tremendous recent progress in crystal growth and device fabrication of the Ge1-ySny and Ge1-x-ySixSny materials, the development of true direct bandgap semiconductors from these Ge-Si-Sn systems is still far from complete, and most of the important properties of these materials are largely remained uncharacterized. Especially, although it has been reported that the indirect to direct transition of Ge1-ySny alloys was to occur at a Sn composition around 6.5%-9.0%, it is still unclear due to the lack of knowledge of fundamental material properties. In this talk, the current status of the advancement of Ge1-ySny alloys will be discussed, including the direct bandgap nature of these materials and their optical properties along with brief descriptions of the epitaxial layers.

报告人简介:

Prof. Meeyi Ryu received the Ph.D. degree in Information and Communications Dept. (Semiconductor Physics), Gwangju Institute of Science and Technology (GIST), Korea and did her postdoctoral research in University of South Carolina, USA from 2001 to 2002. She used to work for Air Force Institute of Technology, USA and University of Dayton Research Institute, USA as Visiting Professor and Semiconductor Research Scientist. At present she is a professor in Department of Physics, Kangwon National University, Korea. In recent years she has published several papers on Nano Letters, Optics Express, Applied Physics Letters. She is dedicated in several fields including

- Electrical and optical characterization studies of Group IV semiconductors such as Ge1-ySny and Ge1-y-xSixSny alloys grown on Si or Ge substrates.

- Study on the optical properties and carrier dynamics of nano structure semiconductors such as In(Ga)As quantum dots grown on GaAs and InP substrates

- Optical characterization of III-V compound semiconductors such as GaAsSb, InGaSb, InAlSb, InGaAs, InGaAs/InAlAs QWs etc. by using photoluminescence (PL) and time-resolved PL.