[Icqm_seminar] weekly seminar 12.24

报告题目： Molecular-Beam Epitaxy of Layered Compounds: Topological Insulator & Transition Metal Dichalcogenide 报告人： Maihai XIE 报告时间： 2014.12.24（周三）下午4:00 报告地点：理科5号楼607 联系人： jianwangphysics@pku.edu.cn 王健 Abstract: In this talk, I shall introduce our recent efforts of growing epitaxial films of layered compounds, Bi2Se3 and MoSe2, which are a topological insulator (TI) and transition-metal dichalcogenide (TMD), respectively, by molecular beam epitaxy (MBE). The TIs and TMDs are quantum materials of great current interests. Epitaxial growth of such films falls into the category of van der Waals epitaxy. I shall first demonstrate growth of single domain Bi2Se3 epifilms by using vicinal InP(111)A substrate, followed by an introduction of growth of a high-index Bi2Se3(221) film on InP(001). For the latter, anisotropic topological surface states are revealed and opportunities of examining the strain effect are suggested. Finally, I will present MBE growth of ultrathin MoSe2, where we discover a surprising network of grain boundary defects. The one-dimensional metallic modes are seen to be modulated by the moiré potentials as well as quantum confinement effect and their formation process will be discussed. About the speaker: Maohai Xie got his Bachelor degree from Tianjin University in 1985, Master degree from Chinese Academy of Science in 1988 and PhD from University of London in 1994. Since 1995 to 1997, he has been a Postdoctoral Research Fellow in the Imperial of Science, Technology and Medicine, London, UK. Then he joined in the faulty of the University of Hong Kong. His Research Interests are Epitaxial growth and properties of ultrathin films and quantum structures of semiconductors, metals, topological insulators and monolayer transition-metal dichalcogenides; Surfaces and electronic structures of ultrathin films; properties related to quantum size effects; Electron diffraction, scanning probe microscopy and photoelectron spectroscopy.