【报告时间】2018年9月21日（周五）下午14:00-16:00
【报告地点】教十一电镜中心一楼125会议室
【报告题目】The atomic structure of tilt grain boundaries in wurtzite semiconductors
【报告人】Dr Pierre Ruterana Centre de Recherche sur les Ions, les Matériaux et la Photonique (UMR6252)
【邀请人】田鹤研究员
【报告人简介】
Dr Pierre Ruterana is a Professor in Centre de Recherche sur les Ions, les Matériaux et la Photonique (UMR6252). He has authored/co-authored more than 330 refereed journal papers, 6 book chapters, 1 edition of scientific book and has made more than 74 invited presentation in the international conferences. His research work has obtained more than 2600 non-self-citations. His research interest includes Hexagonal symmetry materials(Structural units concept in grain boundaries、Nitride semiconductors) and Quantitative High Resolution Transmission Electron Microscopy(Alloys and heterostructures in Nitride semiconductors for light emission、Alloys and heterostructures in Nitride semiconductors for HEMTs、Heteroepitaxy of antimonides for low consumption to autonomous electronic components).
【报告摘要】
Since more than 20 years, an extensive research effort has been carried out on wurtzite semiconductors (nitrides and ZnO) due to their large direct band gaps which allows the possibility for the production of optoelectronic devices (emitters, detectors) from the near infrared to the deep ultra violet range. Using high-resolution electron microscopy, atomistic calculations, and image simulations, we have investigated the atomic structures of the most common extended defects in these materials. In this talk, we shall focus on the a=1/3[11-20] edge threading dislocations. In nitride layers (AlN, GaN, InN), their atomic structure was found to exhibit 5/7, 8 or 4 atom cycles. The two first atomic configurations were observed at a similar frequency for isolated dislocations and low-angle boundaries. The tilt coincidence grain boundaries around the conventional [0001] growth direction have been also been studied. The most frequent are made of 5/7 and 8 atom cycles. However, the reconstruction of some boundaries was only possible by taking into account the occurrence of structural units which include 4-atom ring cycles. In nonsymmetric interfaces, a new structural unit made of 5/4/7 atom rings constitutes the core of grain boundary dislocations.
