Tunable electronic and optical properties of novel ZnSe/AlP van der Waals heterostructure

Abstract

Without the constraint originating from lattice matching, two-dimensional (2D) van der Waals (vdW) heterostructure formed by combining 2D materials provides new possibilities to improve the electronic and optical properties of a single material system. Based on the first-principles calculations of density functional theory, the stacking orders, electronic and optical properties of ZnSe/AlP heterostructure were explored by us. The results demonstrate that the stability of the ABI pattern with the interlayer spacing of 2.65 Å is better than other structures and the charge will accumulate between the ZnSe and AlP monolayers. We find that the band gap of the heterostructure is sensitive to changes of the interlayer spacing, external plane strain and electric field. Under in-plane strain, the transition from direct to indirect band gap will occur in the heterostructure, but this phenomenon is not observed to the cases of external electric field. In addition, the band gap will disappear at the 1.0 V/Å for the AAII pattern (−1.0 V/Å for the ABI pattern), wherefore the heterostructure exhibits metallic properties. Compared with the isolated monolayers, the light absorption of the heterostructure at the blue-ultraviolet region is greatly enhanced. The adjustable band gap and outstanding light absorption capacity indicate that the ZnSe/AlP heterostructure is promising as an effective candidate for the optoelectronic devices.