Optical properties of Ga0.75Al0.25N with interstitial defects

In order to study the influence of interstitial point defects on the optical properties of Ga0.75Al0.25N, three Ga0.75Al0.25N bulk models with Ga, Al, and N interstitial defects were built. And the band structure, dielectric function, complex refractive index, absorption coefficient, reflectivity, and loss function of pure Ga0.75Al0.25N and the Ga0.75Al0.25N with interstitial defects were calculated based on first principles. Results show that the band gap values of Ga0.75Al0.25N with interstitial defects are smaller than that of the pure Ga0.75Al0.25N. And Ga0.75Al0.25N crystals with Ga and Al interstitial defects show n-type property, meanwhile Ga0.75Al0.25N crystal with N interstitial defect show p-type property. The static dielectric constants of crystals with defects are much bigger than that of the pure one. And the metal reflective regions of the crystals shift to lower energy because of the interstitial defects.