Effective carrier separation in zinc oxide and boron phosphide van der Waals heterostructure

Abstract

To construct a preeminent photoelectric appliance, effective carrier separation is the critical question. In this study, a novel inherent staggered type-II van der Waals (vdW) heterostructure composed of zinc oxide (ZnO) and boron phosphide (BP) is designed with being simulated by a first-principle calculation. In the heterostructure, electrons and holes are localized in the monolayer of BP and ZnO respectively. That leads to the separation of photoinduced electron-hole pairs. Furthermore, it shows a prominent absorption coefficient of 104 cm−1 from the ultraviolet to infrared region. Interestingly, the band edges can be regulated and changed to a direct band gap at K point when applying an external electric field donating further separation of carriers. Besides, the heterostructure displays a robust type-II band alignment under −2% ~ +2% strain. These results suggest that two-dimensional (2D) ZnO/BP heterostructure will exhibit widespread application prospects in future photovoltaic and optoelectronic nanodevices.