背景:这项研究探讨了变形对具有空位的单层碲化镉(MoTe2)的电学和光学特性的影响,利用密度泛函理论的基本原理。发现应变和缺陷都会改变单层MoTe2的电特性。在VTe-MoTe2下,发生直接到间接的带隙跃迁。在DTe-MoTe2中,带隙值急剧下降,导带向下变化,载流子浓度上升。DVTe诱导的带隙状态比VTe诱导的带隙状态更接近费米能级。在本文中,选择DTe-MoTe2用于拉伸变形。结果表明,随着拉伸变形的增加,带隙值趋于减小。当拉伸值达到10%时,导带的下限和价带的顶部重叠,系统从半导体转变为金属。考虑到状态的密度,缺失的状态MoTe2主要是由Te-s的参与贡献的,Te-p,和Mo-d轨道。在光学质量方面,吸收和反射峰发生红移和蓝移,分别。希望这些对光电性能的影响将得到广泛应用。
方法:在本研究中,我们利用广义梯度近似平面波伪势方法,结合Perdew-BurkeErnzerhof(PBE)广义函数,并遵循密度泛函理论框架的基本原理。基于MoTe2单层构建了一个3×3×1的超电池作为未掺杂模型,由9个Mo原子和18个Te原子组成。将真空平板沿z方向设置为15A以避免单层之间的相互作用。对于电子结构计算,能量截止设定为450eV。使用Monkhorst-Pack专用K点采样方法进行了每个模型的计算过程和结构优化。晶体优化计算将3×3×1Monkhorst-PackK点网格用于二碲化钼单层,并将9×9×1K点网格用于电子系统分析,分析状态密度和光学特性,分别。对于结构优化,最大力的收敛要求,最大原子位移,最大应力,能量变化定义为0.03eV/µ,0.001贝达,0.05Gpa,和1.0×10-5eV/原子,分别。
BACKGROUND: This study explores the impact of deformation on the electrical and optical characteristics of monolayer cadmium telluride (MoTe2) with vacancies, using the foundational principles of density functional theory. It was discovered that both strain and imperfections alter the electrical characteristics of monolayer MoTe2. Under VTe-MoTe2, a direct-to-indirect band-gap transition occurs. In DTe-MoTe2, the band-gap value reduces dramatically, the conduction band changes downward, and the carrier concentration rises. The DVTe-induced band gap state is closer to the Fermi energy level than the VTe-induced band gap state. In this paper, DTe-MoTe2 is chosen for tensile deformation. The results show that the band-gap value tends to decrease by increasing tensile deformation. When the stretching value reaches 10%, the lower bound of the conduction band and the top of the valence band overlap, and the system is converted from a semiconductor to a metal. Considering the density of states, the missing state MoTe2 is mainly contributed by the participation of Te-s, Te-p, and Mo-d orbitals. In terms of optical qualities, the absorption and reflection peaks are red-shifted and blue-shifted, respectively. It is hoped that these effects on the optoelectronic properties will be widely applied.
METHODS: In this study, we utilize the generalized gradient approximation plane-wave pseudopotential method, incorporating Perdew-Burke Ernzerhof (PBE) generalized functions and following the fundamental principles of the density functional theory framework. A 3 × 3 × 1 supercell was constructed as an undoped model based on a MoTe2 monolayer, which consists of 9 Mo atoms and 18 Te atoms. The vacuum flat plate was set to 15 Å along the z-direction to avoid interactions between the monolayers. For electronic structure calculations, the energy cutoff was set to 450 eV. Each model\'s computational process and structural optimization were carried out using the Monkhorst-Pack specialized K-point sampling approach. Crystal optimization computations used a 3 × 3 × 1 Monkhorst-Pack K-point grid for molybdenum ditelluride monolayers and a 9 × 9 × 1 K-point grid for electronic system analysis, analyzing state density and optical characteristics, respectively. For the structural optimization, the convergence requirements for maximum force, maximum atom displacement, maximum stress, and energy change were defined at 0.03 eV/Å, 0.001 Å, 0.05 Gpa, and 1.0 × 10-5 eV/atom, respectively.