AI 中文总结
本研究通过第一性原理与TCAD模拟，证实Mo₂SeTe₃为弱拓扑半导体，其狄拉克表面态与优异特性可实现亚阈值摆幅低于热发射极限的高性能TFET，为量子电子器件提供了新的多功能材料平台。
AI 中文摘要
本文对准二维过渡金属硫族化合物Mo₂SeTe₃开展了第一性原理及器件层面的研究，发现该材料是具有有限体带隙与对称性保护狄拉克表面态的弱拓扑半导体，具备下一代低功耗量子电子器件的应用潜力。研究观测到由自旋轨道耦合（SOC）驱动的能带反转，伴随约0.75 eV的间接半导体带隙；通过瓦尼尔电荷中心演化与Z₂不变量分析严格确认了拓扑非平凡性，得到弱拓扑指数为(0;001)，迭代格林函数表面态计算也证实了对称性保护表面上存在贯穿体带隙的狄拉克锥导电态。Mo₂SeTe₃还具备优异的动力学与力学稳定性、显著的光学各向异性、高介电极化率、宽红外至可见光吸收范围、大静态介电常数及显著双折射，适合光子与光电子应用。热电输运分析进一步显示，室温附近n型掺杂下该材料载流子迁移率提升，且具有有竞争力的品质因子。通过TCAD模拟实现了采用非局域带间隧穿的双源隧穿场效应晶体管（TFET），其亚阈值摆幅低于热发射极限，具备高开/关电流比，且由SOC诱导的轨道杂化与拓扑增强的带间耦合驱动，隧穿效率显著提升。体-边界对应关系、稳定输运特性与陡降开关特性的同步实现，确立了Mo₂SeTe₃作为用于拓扑及下一代高能效纳米电子器件的多功能量子材料平台的地位。
英文摘要
A first-principles and device-level study of the quasi-two-dimensional transition-metal chalcogenide Mo$_2$SeTe$_3$ is performed. The material is found to be a weak topological semiconductor with a finite bulk band gap and symmetry-protected Dirac surface states, indicating strong potential for next-generation low-power quantum electronic devices. An SOC-driven band inversion accompanied by an indirect semiconducting gap of approximately 0.75 eV is observed. Topological nontriviality is rigorously confirmed through Wannier charge-center evolution and $\mathbb{Z}_2$ invariant analysis, yielding weak topological indices of $(0;001)$, while iterative Green's-function surface-state calculations corroborate Dirac-cone conducting states traversing the bulk gap on symmetry-preserving surfaces. Mo$_2$SeTe$_3$ additionally exhibits exceptional dynamical and mechanical stability, pronounced optical anisotropy, high dielectric polarizability, broad infrared-to-visible optical absorption, a large static dielectric constant, and substantial birefringence, making it favorable for photonic and optoelectronic applications. Thermoelectric transport analyses further reveal enhanced carrier mobility and a competitive figure of merit under $n$-type doping near room temperature. A dual-source tunnel field-effect transistor (TFET) is implemented via TCAD simulations with nonlocal band-to-band tunneling, yielding subthreshold switching below the thermionic limit, a high ON/OFF current ratio, and enhanced tunneling efficiency driven by SOC-induced orbital hybridization and topologically enhanced interband coupling. The concurrent realization of nontrivial bulk-boundary correspondence, robust transport properties, and steep-slope switching characteristics establishes Mo$_2$SeTe$_3$ as a multifunctional quantum material platform for topological and next-generation energy-efficient nanoelectronic devices.
