First-principles study of Mg-Ge co-doping to realize p-type β-Ga2O3 containing divacancy-interstitial complex defects

This study focuses on the divacancy-interstitial complex defects in (3-Ga2O3 (denoted as 2VGa1-Gaic) and enhancement of the p-type conductivity of (3-Ga2O3 containing 2VGa1-Gaic by co-doping. The results indicate that single doping with Group IV elements (Si, Ge, and Sn) reduces the formation energy of 2VGa1-Gaic but increases the acceptor level. Ge doping has the most significant effect on the formation energy, decreasing the formation energy of 2VGa1-Gaic from 4.58 eV to 3.61 eV compared to the undoped case. In comparison, single doping with Mg and Zn atoms decreases the acceptor level of 2VGa1-Gaic but increases the formation energy. Mg doping has a better effect on the acceptor level, decreasing the acceptor level c(0/- 1) of 2VGa1-Gaic from 0.22 eV to 0.04 eV from the valence band top compared to the undoped case. The advantages of the two single doping can be combined by co-doping. Mg-Ge co-doping not only reduces the formation energy but also shallows the acceptor levels, thus improving the hole activation efficiency. Therefore, the p-type conductivity of (3-Ga2O3 containing 2VGa1-Gaic can be improved by using Mg-Ge co-doping, and this new scheme provides a new perspective for the future realization of p-type (3-Ga2O3.