Effects of external electric field on the structural and electronic properties of SeZrS/SeHfS van der Waals heterostructure: A first-principles study

The effects of external electric field on the structural and electronic properties of the SeZrS/SeHfS heterostructure have been studied by first-principles calculations. The results demonstrate that the type-I band alignment can be transformed to the type-II band alignment by an external electric field, achieving the spatial separation of the lowest-energy electron-hole pairs to different monolayers of the SeZrS/SeHfS heterostructure. Furthermore, the approximately linear variations of the band gap with either positive or negative external electric fields can be attributed to the external electric field redistributing the electron concentration, shifting the quasi-Fermi levels and the band edge positions to attain new equilibrium. These results prove the great potential applications of the SeZrS/SeHfS heterostructure in field effect transistors and optoelectronic devices.