拉伸应变对单层MoTe_2电子结构的影响  

Effect of Tensile Strain on Electronic Structure of Single-layer MoTe_2

作　　者：赵旭[1] 陈鹏[1] 张芳[2] 

机构地区：[1]河南师范大学物理与电子工程学院,河南新乡453007 [2]平顶山学院电气信息工程学院,河南平顶山467000

出　　处：《硅酸盐学报》2016年第7期942-947,共6页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金项目(1150409);河南省教育厅自然科学研究计划项目(2011A140018);河南省教育厅科学技术研究重点项目基础研究计划项目(14A140012);国家大学生创新创业训练计划资助项目(201510476043);河南省高等学校重点科研项目(15B140008)资助

摘　　要：采用基于密度泛函理论的第一性原理计算方法计算了单层Mo Te_2的能带结构和态密度,研究了拉伸应变对单层Mo Te_2电子结构的影响。结果表明:与单轴应变相比,双轴应变对Te–Te原子间距和Te–Mo–Te键角等晶格参数的影响更大,键长和键角的变化会影响原子不同轨道间的耦合强度,因此在调节单层Mo Te_2的带隙宽度时,施加双轴应变比单轴应变更有效。对单层Mo Te_2施加单轴应变后,其带隙宽度随着应变的增加缓慢减小,能带结构与未施加应变时相同,仍为直接带隙。而施加双轴应变后,单层Mo Te_2的带隙宽度明显变小,当应变接近6%时,其能带结构由直接带隙变为间接带隙。通过对投影电荷密度的分析,揭示了施加双轴拉伸应变时能带结构变化的根本原因。The band structure and state density of monolayer MoTe2 were calculated by the first-principles method based on the density functional theory. The effect of tensile strain on the electronic structure of monolayer MoTe2 was investigated. The calculated results indicate that the biaxial strain has a greater effect on the lattice parameters of Te–Te distance and Te–Mo–Te bond angle rather than the uniaxial strain. The change of bond length and bond angle affects the coupling strength between different atom orbitals, therefore the biaxial strains are more effective than the uniaxial strains in modulating the bandgap of monolayer MoTe2. Under the uniaxial strains, the calculated bandgap decreases slightly as the strain increases, while the band structure is preserved and the monolayer MoTe2remains as a semiconductor with a direct bandgap. Under the biaxial strains, the calculated bandgap decreases obviously as the strain increases, a certain biaxial strain （6%） results in the transition from direct to indirect gap for monolayer MoTe2. The fundamental reason for the change of band structure under the biaxial tensile strain was analyzed based on the further analysis of the projected charge density for monolayer MoTe2.

关 键 词：第一性原理 二碲化钼 拉伸应变 电子结构 

分 类 号：O469[理学—凝聚态物理]