Influence of shear strain on the electronic properties of monolayers MoS2, WS2, and MoS2/WS2 vdW heterostructure.

Abstract

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. 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 20Å was added to avoid interactions between the atomic layers. A cutoff energy of 500eV 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 × 10-5eV, and the thresholds for interatomic forces and stresses were set to 0.01eV/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.