背景:这项研究调查了单层MoS2,WS2和MoS2/WS2范德华异质结构(vdWHs)的动态稳定性以及剪切应变对其电子性质的影响。结合能和声子色散的计算结果表明MoS2/WS2vdWH具有优异的动态稳定性。MoS2/WS2vdWH,具有II型带对准和间接带隙,减少电子-空穴复合,提高光电器件的效率和性能。在剪切应变下,有效地调制了MoS2,WS2和MoS2/WS2vdWH单层的带隙大小和类型,以及MoS2/WS2vdWH中的层间电荷重新分布。这项工作揭示了单层MoS2,WS2和MoS2/WS2vdWH在剪切应变下的电子性质的可调性,为开发光电器件提供新的可能性和解决方案,传感器,和相关领域。
方法:这项工作采用MaterialsStudio软件包中的CASTEP模块进行第一原理计算。在几何优化过程中,使用GGA-PBE功能交换相关电位来考虑离子-电子相互作用。S的电子配置,Mo,和W原子被选择为它们的典型排列:(3s2p4),(4s2p6d55s1),和(5s2p6d46s2),分别。添加了20µ的真空层,以避免原子层之间的相互作用。设置500eV的截止能量用于结构优化和自洽计算,具有6×6×1和9×9×1的k点网格。在结构优化过程中,能量收敛准则设置为1×10-5eV,原子间力和应力的阈值设置为0.01eV/µ和0.01GPa,分别。Grimmer的DFT-D2校正考虑了MoS2/WS2vdWH中的层间vdW相互作用,同时使用线性响应方法计算声子色散。
BACKGROUND: This study investigates the dynamic stability of monolayers MoS2, WS2, and MoS2/WS2 van der Waals heterostructures (vdWHs) and the influence of shear strain on their electronic properties. The computational results of the binding energy and phonon dispersion demonstrate the excellent dynamic stability of MoS2/WS2 vdWHs. The MoS2/WS2 vdWH, with a type-II band alignment and an indirect bandgap, reduces electron-hole recombination, enhancing the efficiency and performance of optoelectronic devices. Under shear strain, the bandgap size and type of monolayers MoS2, WS2, and MoS2/WS2 vdWHs were effectively modulated, along with the interlayer charge redistribution in the MoS2/WS2 vdWHs. This work reveals the tunability of the electronic properties of monolayers MoS2, WS2, and MoS2/WS2 vdWHs under shear strain, offering new possibilities and solutions for developing optoelectronic devices, sensors, and related fields.
METHODS: This work employed the CASTEP module within the Materials Studio software package for first-principles calculations. Ultrasoft pseudopotentials were employed during geometry optimizations to account for ion-electron interactions using the GGA-PBE functional for exchange-correlation potentials. The electronic configurations of the S, Mo, and W atoms were chosen as their typical arrangements: (3s2p4), (4s2p6d55s1), and (5s2p6d46s2), respectively. A vacuum layer of 20 Å was added to avoid interactions between the atomic layers. A cutoff energy of 500 eV was set for structural optimization and self-consistent calculations, with k-point grids of 6 × 6 × 1 and 9 × 9 × 1. During the structural optimization process, the energy convergence criterion was set to 1 × 10-5 eV, and the thresholds for interatomic forces and stresses were set to 0.01 eV/Å and 0.01 GPa, respectively. Grimmer\'s DFT-D2 correction accounted for the interlayer vdW interactions in the MoS2/WS2 vdWH, while the phonon dispersion was calculated using the linear response method.