新型层状Bi2Se3的第一性原理研究  

First-principle study of new phase of layered Bi2Se3

作　　者：郭宇 周思 赵纪军 Guo Yu;Zhou Si;Zhao Ji-Jun(Key Laboratory of Materials Modification by Laser,Ion,and Electron Beams,Ministry of Education,School of Physics,Dalian University of Technology,Dalian 116024,China)

机构地区：[1]大连理工大学物理学院,三束材料改性教育部重点实验室,大连116024

出　　处：《物理学报》2021年第2期249-256,共8页Acta Physica Sinica

基　　金：中国博士后科学基金(批准号:BX20190052,2020M670739);国家自然科学基金(批准号:11974068);中央高校基础研究经费(批准号:DUT20LAB110)资助的课题.

摘　　要：近年来,在石墨烯研究热潮的推动下,众多种类丰富、性能各异的二维化合物材料相继被发现,其中一些二维材料具有多种同素异构体,进而呈现出更丰富的性质.层状Bi2Se3由于其独特的物理性质,受到人们广泛的关注,而它的同素异构体尚未有人研究.本文采用基于密度泛函理论的结构搜索方法,预测了一个稳定的b-Bi2Se3新相,它具有良好的动力学和热力学稳定性,并在低Bi2Se3源化学势条件下容易形成.单层b-Bi2Se3是一个直接带隙为2.44 eV的二维半导体,其电子载流子有效质量低至0.52m0,在可见光范围内具有高达10^5 cm^–1的光吸收系数,并且能带边缘位置适中,可用于光催化水分解制氢气.此外,由于b-Bi2Se3在垂直层面方向的镜面对称性破缺,能够产生面外极化强度,具有0.58 pm/V的面外压电系数.鉴于其新颖的电子特性,二维b-Bi2Se3在未来的电子器件中可能发挥重要的作用.Recently,the boom of graphene has aroused great interest in searching for other two-dimensional(2D)compound materials,which possess many intriguing physical and chemical properties.Interestingly,2D allotropes of differing atomic structures show even more diverse properties.The Bi2Se3 has attracted much attention due to its unique physical properties,while its allotrope has not been investigated.Based on firstprinciple calculations,here in this work we predict a new phase of Bi2Se3 monolayer with outstanding dynamic and thermal stabilities,named as b-Bi2Se3.Notably,the b-Bi2Se3 monolayer is a semiconductor with a modest direct band gap of 2.40 eV and small effective mass down to 0.52 m0,large absorption coefficient of 10^5 cm^–1 in the visible-light spectrum,suitable band edge positions for photocatalysis of water splitting.Moreover,the breaking of mirror symmetry in b-Bi2Se3 along the out-of-plane direction induces vertical dipolar polarization,yielding a remarkable out-of-plane piezoelectric coefficient of 0.58 pm/V.These exceptional physical properties render the layered Bi2Se3 a promising candidate for future high-speed electronics and optoelectronics.

关 键 词：半导体 Bi2Se3 同素异构体 电子结构 层状材料 

分 类 号：TQ135.32[化学工程—无机化工]