报告题目：CVD-grown triangular WS2 monolayer and bilayer crystals
----- Optical and electrical properties
报 告 人：柳忠元 教授 （燕山大学）
主 办：物理工程学院、激光研究所
时 间：2016年12月12日 上午：9:30
地 点：物理楼313报告厅
Abstract：Triangular monolayer WS2 crystals of size ranging from several to ~130 mm were grown by chemical vapor deposition (CVD). In fluorescence (FL) images and photoluminescence (PL) maps of intensity, the monolayer WS2 crystals exhibit significantly enhanced light emission with increasing size. In monolayer crystals of large sizes, PL maps of intensity gives a fascinating pattern with stair-type enhanced intensity from the edges to the central region. As revealed by PL spectra at 77 K, the defects of S vacancies are lower in concentration in larger monolayer crystals and spatially inhomogeneous from the edges to central region, indicating the strong influence of size-dependent chemical composition on the optical property. Additionally, the monolayer WS2 crystals of larger sizes (>30 mm) exhibit much more excellent electrical performance than those of smaller sizes (<20 mm). In our CVD-grown large monolayer WS2 crystals, the achieved carrier mobility can be as high as 11.5 cm2V-1s-1. Based on the CVD-grown monolayer WS2 crystals and liquid-exfoliated SnS quantum dots, phototransistors were also fabricated to investigate the enhanced photoresponse of monolayer WS2 with the help of SnS quantum dots.
报告人简介：柳忠元，主要研究方向涉及以下几个领域：1）磁性薄膜、多层膜与器件；2）过渡族金属硫属化合物、黑磷等二维半导体材料的制备、性能与器件；3）过渡族金属碳化物硬质合金；4）超硬材料。主持承担了包括国家973课题、国家杰出青年基金、国家自然科学基金面上等12个项目的研究工作，并参加了国家973、国家自然基金委创新群体基金等5个项目的研究工作；2010年获国家杰出青年基金支持，2015年入选国家百千万人才工程，被授予国家“有突出贡献中青年专家”荣誉称号。迄今为止，已在Nature、Advanced Materials、ACS nano、Advanced Functional Materials、Physical Review Letters等国际著名学术杂志上发表被SCI收录论文160余篇，近五年60余篇。
