Origin of the visible light absorption of GaN-Rich Ga1-xZnxN1-xOx (x=0.125) solid solution

The structure, electronic, and optical properties of GaN-rich Ga1-x,ZnxN1-xOx (x = 0.125) solid solution have been systemically by means of density functional theory calculations (DFT) within the generalized gradient approximation (GGA). Our calculated results indicate that between the N 2p and Zn 3d states there exists a strong p-d coupling, which results in a narrower band gap than that of GaN. According to our calculation, the narrowed band gap of the solid solution leads to the absorption of visible light and thus results in the photocatalytic activity under visible light. We also found that the position of the O atom has an obvious effect on the band gap of the solid solution. These results can give an explanation for the origin of the visible light activity of the solid solution and are in agreement with experimental observation.