Tunable Electronic Properties of Type-II SiS ₂/WSe ₂ Hetero-Bilayers

Abstract

First-principle calculations based on the density functional theory (DFT) are implemented to study the structural and electronic properties of the SiS ₂/WSe ₂ hetero-bilayers. It is found that the AB-2 stacking model is most stable among all the six SiS ₂/WSe ₂ heterostructures considered in this work. The AB-2 stacking SiS ₂/WSe ₂ hetero-bilayer possesses a type-II band alignment with a narrow indirect band gap (0.154 eV and 0.738 eV obtained by GGA-PBE and HSE06, respectively), which can effectively separate the photogenerated electron–hole pairs and prevent the recombination of the electron–hole pairs. Our results revealed that the band gap can be tuned effectively within the range of elastic deformation (biaxial strain range from −7% to 7%) while maintaining the type-II band alignment. Furthermore, due to the effective regulation of interlayer charge transfer, the band gap along with the band offset of the SiS ₂/WSe ₂ heterostructure can also be modulated effectively by applying a vertical external electric field. Our results offer interesting alternatives for the engineering of two-dimensional material-based optoelectronic nanodevices.