Influence of ZnO Doping on Energy Band Structure and Photocatalytic Activity of GaN/ZnO Solid Solutions

This study examines the effects of diverse ZnO doping levels on the energy band structure of GaN/ZnO solid solutions. A comprehensive analysis of 350 GaN/ZnO solid solution structures was conducted, encompassing measurements of their respective band gap sizes. The findings indicate that the band gap of the solid solution structure initially undergoes a rapid decrease with increasing ZnO content, eventually stabilizing at approximately 0.05 eV. Subsequently, a slight increase to 0.2 eV is observed at higher ZnO concentrations. This reduction in the band gap is primarily attributed to the enhanced formation of Zn-N bonds. By manipulating the ZnO content, the solid solution offers the capability for continuous band gap control. An in-depth analysis of the energy band and density of states reveals that repulsive interactions between the N 2p and Zn 3d orbitals are responsible for the observed band gap narrowing. Furthermore, a significant enhancement in visible light responsiveness of GaN/ZnO solid solutions is observed with increasing ZnO concentrations. This enhancement is accompanied by a noticeable red shift in the absorption peak within the visible light region. In summary, GaN/ZnO solid solutions exhibit a substantial improvement in their visible light photocatalytic performance.