First-principle study of optical properties of (N, Ga) codoped ZnO

To analyze the electronic structure and optical properties of (N, Ga) codoped ZnO, the parameters such as band structure, density of states, dielectric constant, absorption and reflection spectra of pure ZnO, N–Ga and 2N–Ga codoped ZnO were calculated by using first-principle method based on DFT (Density Functional Theory). The results demonstrated that the band gap of (N, Ga) codoped ZnO narrows, and 2N–Ga codoping can obtain a high-quality and more stable p-type ZnO. Compared with pure ZnO, the real and imaginary part of dielectric function of (N, Ga) codoped ZnO move toward a lower energy side; in ultraviolet region, the absorption spectrum reduces greatly, and the blue shift of reflectivity spectrum is observed; while in infrared region, the reflectivity spectrum of 2N–Ga codoped ZnO is twice that of pure ZnO or N–Ga codoped ZnO. The results provided certain theoretical reference for the study of ZnO-based transparent conductive thin films.