2D anisotropic type-Ⅰ SiS vdW heterostructures toward infrared polarized optoelectronics applications

摘要

Two-dimensional (2D) SiS has been drawing much attention due to its direct band gap and strong optical anisotropy under both two structural phases, namely, Pmma-SiS and Pma2-SiS. Here, we theoretically design Pmma-/Pma2-SiS van der Waals heterostructures (vdWH) through first-principles for the application of polarized light emitting devices. The calculations show that 2D Pmma-/Pma2-SiS vdWH possesses direct type-I band alignment with suitable band offsets (Delta Ec = 0.163 eV, Delta Ev = 0.202 eV), strong linear dichroism and high optical absorptions (similar to 105 cm(-1)). Moreover, type-II band alignment with direct band gap can be achieved with the effect of external electric field, separating spatially the low-energy electron-hole pairs. Further, the band offsets display linear increase with the increase of external electric field, which indicates the recombination of charge carriers can be easily modulated. These results imply that Pmma-/Pma2-SiS vdWH can provide a promising way to design polarized infrared light emitting devices through using 2D anisotropic materials to form vdWH with type-I band alignment.