2D multifunctional SiAs 2 /GeAs 2 van der Waals heterostructure.

The structural and electronic properties of two-dimensional (2D) SiAs 2 /GeAs 2 van der Waals heterostructure (vdWH) and its applications are investigated by combing first-principles calculations and Silvaco Atlas simulations. The stable SiAs 2 /GeAs 2 vdWH exhibits an indirect bandgap of 0.99 eV in type II band alignment for light detection and energy harvesting. The vdWH can exhibit a direct bandgap up to 0.66 eV by applying an appropriate electric field ( E ext ). Due to the E ext induced charge redistribution, its band alignment can be transformed from type II to type I for light-emitting. Further simulation shows that the band alignment of SiAs 2 /GeAs 2 vdWH can be tuned back and forth between type II and type I by gate voltage in a single field-effect transistor for multiple functional applications. These results may be useful for applications of the SiAs 2 /GeAs 2 heterostructure in future electronic and optoelectronic devices.