报告题目：Interlayer coupling and layer-dependent electronic structure in 2D materials

报 告 人：Zexiang Shen

Division of Physics and Applied Physics, School of Materials Science and Engineering, Nanyang Technological University, Singapore

Abstract: Following the extensive research work on graphene, a lot of attention has now been focused on two dimensional transition metal dichalcogenide (2D TMD) materials which can in principle compensate some of the disadvantages of graphene, such as lack of an energy bandgap. 2D TMD often show very strong layer-dependent properties. For example, their properties can be strongly influenced by the stacking of the layers, the relative orientation of the layers and the number of layers. Detailed understanding of the inter-layer interaction will help greatly in tailoring the properties of 2D TMD materials for applications. Raman/Photoluminescence (PL) spectroscopy and imaging have been extensively used in the study of nano-materials and nano-devices. They provide critical information for the characterization of the materials such as electronic structure, optical property, phonon structure, defects, doping and stacking sequence.

In this talk, we use Raman and PL techniques to study few-layer MoS2 samples. The Raman and PL spectra show clear correlation with layer-thickness and stacking sequence. Our ab initio calculations reveal that difference in the electronic structures mainly arises from competition between spin-orbit coupling and interlayer coupling in different structural configurations.

Dr. Ze Xiang Shen is a Professor in the School of Physical and Mathematical Sciences, and the School of Materials Science and Engineering, Nanyang Technological University. He is the Program Chair of the Interdisciplinary Graduate School. He concurrently holds the position of Co-Director, Centre for Disruptive Photonics Technologies.

His main research areas include 2D materials, especially graphene and TMD materials. His work involves spectroscopic and theoretical study of few-lay graphene and folded graphene, inter-layer coupling and the effect of stacking dependence on the electronic structure of TMD materials. He also works graphene intercalation study, graphene based composites for energy harvesting (Li Ion batteries and supercapacitors) and nano electronics; fundamental study of graphene such as electronic structures, doping, energy band gaps. He also works on developing near-field Raman spectroscopy/imaging techniques and the study of plasmonics structures where some very fundamental questions remain to be answered.

He was awarded the NTU Nanyang Award for Research and Innovation 2009 as well as the Gold Medal for Research Excellence by Institute of Physics Singapore in 2011. Shen authored over 400 peer reviewed journal papers, 4 book chapters, edited 3 books and over 300 conference papers. He has a citation of >12,000 and H-index of 60.

地 点：前卫南区唐敖庆楼C区603报告厅

时 间：2015年7月9日（周四）下午14:00

举办单位：超硬材料国家重点实验室

物理学院

原子与分子物理研究所

吉林省物理学会

中国物理学会高压物理专业委员会

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