Theoretical design of a photodetector based on a two-dimensional SnSe2/GaP type-II heterostructure

Abstract

The low-dimensional structure and excellent optical properties of two-dimensional (2D) materials have made them a hot theme for research in materials science. In this study, the geometrical properties, electrical properties, and optical characteristics of a new SnSe₂/GaP heterostructure are explored using first principles. We also calculated the effect of different rotational angle stacking and doping on the optoelectronic properties of the SnSe₂/GaP heterostructure. The results show that the SnSe₂/GaP heterostructure is a type-II heterostructure with an indirect bandgap of 0.439 eV, and the photogenerated electron–hole pairs can be effectively separated at the heterogeneous interface. The heterostructure bandgap can be adjusted to zero by modulating the interlayer distance or by applying electric fields and strains, enabling semiconductor–metal leapfrogging. It is noteworthy that when imposing an electric field of 0.4 V Å⁻¹, the SnSe₂/GaP heterostructure varies from type-II heterostructure into type-I. In particular, unlike the two monolayers, the formation of the SnSe₂/GaP heterostructure results in a significant increase in absorbance, especially in the UV absorption region, and has a wider light absorption range. This shows that SnSe₂/GaP heterostructure has great potential for future multifunctional optoelectronic devices.