First-principles calculations of electronic and optical properties of aluminum-doped β-Ga2O3 with intrinsic defects

In this manuscript, the effects of intrinsic defects on the electronic and optical properties of aluminum-doped β-Ga2O3 are investigated with first-principles calculations. Four types of defect complexes have been considered: AlGa2O3VO (Al-doped β-Ga2O3 with O vacancy), AlGa2O3VGa (Al-doped β-Ga2O3 with Ga vacancy), AlGa2O3Gai (Al-doped β-Ga2O3 with Ga interstitial) and AlGa2O3Oi (Al-doped β-Ga2O3 with O interstitial). The calculation results show that the incorporation of Al into β-Ga2O3 leads to the tendency of forming O interstitial defects. And the bandgap of AlGa2O3 is 4.975 eV, which is a little larger than that of intrinsic β-Ga2O3. When O vacancies exist, a defect energy level is introduced to the forbidden band as a deep donor level, while no defective energy levels occur in the forbidden band with O interstitials. After Al-doped, a slightly blue-shift appears in the intrinsic absorption edge, and an additional absorption peak occurs with O vacancy located in 3.69 eV.