Electric-field-induced semiconductor-semimetal phase transition of GeTe/SnSe van der Waals heterojunction

The electronic structure and optical property of GeTe/SnSe van der Waals heterojunction are investigated by first-principles method. We find GeTe/SnSe van der Waals heterojunction is a type-II heterojunction with an indirect band gap of 0.71 eV. The band gap can be tuned and semiconductor-semimetal phase transition is observed under both positive and negative electric field. The band offset of GeTe/SnSe van der Waals heterojunction can be controlled, and thus the potential barrier can be controlled by applying a gate voltage. Combined with the calculation of effective mass and absorption spectrum we predict that GeTe/SnSe van der Waals heterojunction has important applications in the fields of solar cell and photodetector devices.