报告题目1：二维范德华异质结构电子与光电器件构筑与性能调控
报 告 人：张铮 副教授，北京科技大学
时 间：2021年1月6日（星期三）下午15:00-16:00
地 点：国家纳米科学中心 南楼四层会议室
邀 请 人：刘新风 研究员
报告摘要：
半导体材料是信息产业的基础，由半导体材料构建的基本电子器件单元是芯片与集成电路技术的核心。随着尺寸减小，传统半导体异质结由于界面晶格失配导致的悬挂键诱导载流子散射和捕获效应，显著降低了载流子输运效率、提高了器件功耗。因此，探索突破亚十纳米物理极限的变革性材料与新原理器件是信息产业与半导体材料产业亟待解决的科学技术难题。以MoS2为代表的过渡金属硫族化合物(TMDs)是典型的二维半导体材料，具有独特的电子结构、优异的半导体特性和超平整的表面结构，将不同二维半导体材料通过精确转移、范德华堆垛等形式构筑的范德华异质结构打破了材料结构的晶格匹配、电子结构的能带匹配以及物理化学性质强关联等因素带来的束缚，可以自由选择不同性质的二维材料通过范德华作用力堆砌组装而成，在未来高性能、低功耗电子与光电功能器件方面具有巨大潜力。如何高效调控二维半导体材料性能，揭示范德华异质界面载流子输运的规律，设计构筑新原理高性能范德华异质结光电器件是亟待解决的关键问题。本报告将从缺陷工程、应变工程和静电掺杂效应等方面，阐述报告人近年来围绕TMDs二维半导体材料光电器件的构筑与性能调控方法研究成果。
报告人简介：
张铮，北京科技大学副教授，国家人才计划青年项目获得者。主要从事低维半导体材料异质结构构筑及其在电子与光电器件应用基础研究，发表SCI论文90余篇，他引2200余次；以第一或通讯作者在Nature Energy、Nature Communications、Science Advances、Advanced Materials、Advanced Functional Materials、ACS Nano等期刊发表论文40余篇；参与撰写英文专著一部；申请专利20项，授权发明专利12项；以第五完成人获得国家自然科学奖二等奖一项。主持承担了国家自然科学基金面上基金、青年科学基金、北京市自然科学基金重点研究专题、中国博士后科学基金特别资助项目等；作为项目骨干参与了国家重大科学研究计划纳米科技重点专项、国家自然科学基金重大项目、国家重大科学仪器研制项目；担任中国体视学学会理事、中国体视学学会材料学分会副秘书长。
报告题目2：Quantum properties of 2D magnetic semiconductors revealed by optical spectroscopy
报 告 人：叶堉 研究员，北京大学
时 间：2021年1月6日（星期三）下午16:00-17:00
地 点：国家纳米科学中心 南楼四层会议室
邀 请 人：刘新风 研究员
报告摘要：
Spectroscopy is one of the most powerful technique to reveal electronic structures and magnetic properties of 2D materials. We performed spectroscopic studies on layered chromium thiophosphate (CrPS4), a ternary antiferromagnetic semiconductor with photoluminescence in near-infrared wavelength region and observed Fano resonance when CrPS4 experiences phase transition into the antiferromagnetic state below Néel temperature (38 K). The temperature and external magnetic field dependences of the Fano resonance provide insights into the photon-emitting coherent electronic transition of CrPS4 and their connection to the magnetism related broken symmetry. Using magnetic circular dichroism, we measured the thickness-dependent magnetic properties of the quaternary van der Waals ferromagnetic semiconductor AgVP2Se6 and topological antiferromagnetic MnBi2Te4. When the thickness of the AgVP2Se6 flakes is reduced, enhanced out-of-plane magnetic anisotropy is observed. We show that few-layered MnBi2Te4 exhibits evident odd-even layer-number effect, i.e. the oscillations of the coercivity of the hysteresis loop and the spin-flop transition, concerning the Zeeman energy and magnetic anisotropy energy
报告人简介：
Yu Ye is an assistant professor in School of Physics at Peking University. He received his Ph.D. degree in condensed matter physics from Peking University on 2012. Prior to joining PKU in July 2016, Yu was working as a postdoctoral researcher at University of California, Berkeley. His group currently is interested in light-matter interactions and electrical transport properties in condensed matter physics, with an emphasis on novel physical phenomena emerging in atomically-thin materials, van der Waals heterostructures and surfaces/interfaces by nanoscale device designs, low-T-high-B optical spectroscopy, and electrical transport measurements. Yu published more than 80 research papers and earned >4000 citations with an h-index of 32.
