Optoelectronic properties of bilayer van der Waals WSe2/MoSi2N4 heterostructure：A first-principles study

Abstract

Suitable bandgap semiconductors, especially those with the superb optical property and high carrier mobility as well as tunable electronic property, are of great significance for the development of optoelectronic devices . In this paper, we construct a vertical bilayer WSe 2 /MoSi 2 N 4 van der Waals heterostructure (vdWH) and systematically investigate its crystal structure, stability and optoelectronic properties by first-principles calculations. Firstly, we find that the stable WSe 2 /MoSi 2 N 4 bilayer is a type-I vdWH with the direct bandgap of 1.57 eV mainly determined by the component WSe 2 monolayer. Furthermore, we show that the WSe 2 /MoSi 2 N 4 vdWH has high mobility up to 10 4 cm 2 V −1 s −1 and enhanced optical absorption compared to the isolated WSe 2 and MoSi 2 N 4 monolayers. More importantly, under the external electric field the WSe 2 /MoSi 2 N 4 bilayer can form the tunable bandgap type-II vdWH, in which hole and electron can be effectively separated. Our findings not only provide a strategy for tailoring the electronic properties of two-dimensional MoSi 2 N 4 material, but also have potential applications in optoelectronic devices. • By first-principles calculations, we construct a stable type-I WSe 2 /MoSi 2 N 4 bilayer heterostructure with the direct bandgap. • WSe 2 /MoSi 2 N 4 heterostructure has high mobility and enhanced optical absorption. • Electric field can easily tune the electronic property of WSe 2 /MoSi 2 N 4 bilayer.