The optical properties of GaN (001)surface modified by intrinsic defects from density functional theory calculation

Based on the first principle density functional theory calculation, the effect of two kinds of intrinsic point defects on the optical properties of GaN polar surface was investigated in this paper. It was found that the band gap and the positions of the electronic states changed with the presence of defects, resulting in a change in the optical properties. The static dielectric function decreased slightly, the numbers and the positions of the peaks in the imaginary part of dielectric function change a lot, the intensity of the absorption spectrum decreased, significant of shrinking of the absorption spectrum was observed, and the electron energy loss spectra peak broadened along with the decrease in the peak height. In the case of the GaN polar surface with the N vacancy, the range of the absorption spectrum comprised the visible light, and the presence of the N vacancy resulted in a low energy plasma excitation peak.