报告题目：Unusual materials properties of Cu-containing semiconductors：The role of metal d orbitals

报告人：Su-Huai Wei(魏苏淮) Beijing Computational Science Research Center

报告时间：2022年8月15日上午10：30

报告地点：必赢电子游戏网站中心校区物理楼333会议室

腾讯会议：600 781 753

报告摘要

It has been shown that most semiconductors exhibit a metal d subband near or inside the main valence band. Using band structure calculation techniques, which treat the outermost d electrons on the same footing as other valence electrons, we study their effects on the material properties. We find that p-d and/or s-d repulsion and hybridization (i) lower the band gaps, (ii) reduce the deformation potential of the valence band maximum states, (iii) increase the band offsets between common anion compounds, (iv) reduce the spin-orbit splitting, (v) alter the sign of the crystal-field splitting, and (vi) is responsible for the negative exchange splitting in magnetic semiconductors. Among all the metal elements, Cu has the highest fully occupied d orbital energy which is close to its unoccupied s orbital, thus cuprates, Cu chalcogenides, and Cu halides often exhibit some unusual physical properties such as unusual crystal structures and band structures, deep Cu acceptor levels in II-VI semiconductors, fast ionic diffusion, ultralow thermal conductivity, and even superconductivity. In this talk, I will discuss the electronic origin for these unusual behaviors.

报告人简介

魏苏淮，北京计算科学研究中心教授，材料能源研究部主任，美国物理学会会士，美国材料学会会士。1981年毕业于复旦大学，1985年于美国威廉玛丽学院获理学博士学位。1985年至2015年，在美国国家可再生能源实验室（NREL）工作，担任过理论研究室主任、国家实验室Fellow 。主要从事半导体物理的理论研究，是计算半导体缺陷和半导体掺杂方面的知名专家。在半导体能带计算、掺杂机制、d和f电子在II-IV簇半导体的效应、自旋电子系统、半导体带阶和压力效应、以及半导体纳米团簇等领域中做了大量原创性的工作。发展了全电子FLAPW计算程序、无序合金和半导体缺陷的精确计算模型和方法；提出了半导体在平衡态下存在掺杂极限的机理和克服掺杂极限的方法；对一系列光电材料包括太阳能材料的性质做了系统的理论解释。已发表论文500多篇，其中70多篇发表在《物理评论快报》（Physical Review Letters）上，被引用次数>60000次，H因子>120  。

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