题目

First-Principles Theory of Epitaxial Film Growth

报告人

Prof. Shengbai Zhang (张绳百)

Department of Physics, Applied Physics, & Astronomy,

Rensselaer Polytechnic Institute, USA

时间

2017年3月30日（星期四）下午3：00

地点

微尺度国家实验室9004会议室

Prof. Shengbai Zhang received his B. S. degree in electronic engineering from Jilin University in 1982 and his Ph. D. degree in Physics from the University of California at Berkeley in 1989 under Marvin L. Cohen. He moved to Xerox PARC as a postdoc, before joining the National Renewable Energy Laboratory in 1991. In 2008, he became the Senior Kodosky Constellation Chair Professor and Professor in Physics at Rensselaer Polytechnic Institute. His computational research covers a wide range of materials physics from bulk properties, defect structures, to surface sciences. His recent work involves green photovoltaic materials, ultrafast phase change memory materials, topological carbon, two-dimensional layered structures, non-equilibrium growth, and excited state dynamics. He has published more than 360 papers, including 57 PRL, 11 Nano Letters, 5 JACS, 4 Nature Communications, and 3 PNAS, with a non-self-citation = 15,957 and H-index = 64 (Web of Science), or total-citation = 22,921 and H-index = 69 (Google Scholar). He is a fellow of the American Physical Society.

报告摘要

Recent years witness the resurgence of van der Waals (vdW) epitaxy where two materials of drastically different physical properties are brought together. Ample examples exist for two-dimensional (2D) material on three-dimensional (3D) substrate and 2D material on 2D substrate, but few exists for 3D material on 2D substrate. Here, by a comparative study of CdTe film on layered NbSe₂ and on graphene substrates, we illustrate the key role of interfacial dative bond between filled anion orbitals and empty cation orbitals in enhancing the vdW epitaxy. While understanding interfacial chemistry is important, to understand growth, a first-principles theory, which is simple enough yet encompasses the complexity of growth kinetics, is vitally important but currently lacking. Here, we develop a first-principles effective chemical potential approach that bridges between different stages of non-equilibrium growth from pre-nucleation, nucleation, to island growth. Application to molecular beam epitaxy (MBE) of Bi₂Se₃, which is also a layered material, reveals a high density of nuclei as the reason hindering the growth of large-size high-quality topological insulators, in qualitative agreement with experiment.