Two-Dimensional Boron Phosphide/MoGeN van der Waals Heterostructure: A Promising Tunable Optoelectronic Material.

A van der Waals (VDW) heterostructure offers an effective strategy to create designer physical properties in vertically stacked two-dimensional (2D) materials, and offers a new paradigm in designing novel 2D heterostructure devices. In this work, we investigate the structural and electronic features of the BP/MoGeN heterostructure. We show that the BP/MoGeN heterostructure exists in a multiple structurally stable stacking configuration, thus revealing the experimental feasibility of fabricating such heterostructures. Electronically, the BP/MoGeN heterostructure is a direct band gap semiconductor exhibiting type-II band alignment, which is highly beneficial for the spatial separation of electrons and holes. Upon forming the BP/MoGeN heterostructure, the band gap of the constituent BP and MoGeN monolayers are substantially reduced, thus allowing the easier creation of an electron-hole pair at a lower excitation energy. Interestingly, both the band gap and band alignment of the BP/MoGeN heterostructure can be modulated by an external electric field and a vertical strain. The optical absorption of the BP/MoGeN heterostructure is enhanced in both the visible-light and ultraviolet regions, thus suggesting a strong potential for solar cell application. Our findings reveal the promising potential of the BP/MoGeN vdW heterostructure in high-performance optoelectronic device applications.