Electronic structures of Zn1−xGaxO1−xNx and band offsets of the ZnO/Zn1−xGaxO1−xNx heterojunction across the entire concentration range from first principles

Abstract

Band offsets at the heterointerfaces play a key role in defining the functionality of optoelectronic devices. In this work, the band gaps of wurtzite Zn_1−xGa_xO_1−xN_x alloys and the band offsets of the lattice matched ZnO/Zn_1−xGa_xO_1−xN_x heterojunction across the entire concentration range of GaN were investigated by the modified Becke–Johnson (mBJ) semi-local exchange combined with the coherent potential approximation (CPA). The calculated band gaps of Zn_1−xGa_xO_1−xN_x alloys can be tuned by the concentration of the doping GaN and show a strong band gap bowing. The heterojunctions ZnO/Zn_1−xGa_xO_1−xN_x form either type I or type II band alignment by adjusting the concentration of GaN; especially, when the concentration is in the range of 0.8 < x < 0.97, the band gaps of Zn_1−xGa_xO_1−xN_x cover visible light, and the heterojunctions show type II band alignment, which would help to enhance the solar light adsorption ability and improve the carrier collection efficiency in the design and optimization of ZnO and GaN-based heterojunctions for the applications of optoelectronics and photocatalysis.