Defect stability and electronic structure of doped β-Ga2O3: A comprehensive ab initio study

Using ab initio calculations, we systemically investigated the energetics and stability of various defects (vacancy, interstitial atom, anti-site defect and dopant atom), optical properties of β-Ga2O3 with O monovacancy, electronic structures of β-Ga2O3 doped with P, Ge, Sn, Si, N and Cl, as well as the effect of the dopant atom on the energetics of monovacancy in these doped β-Ga2O3. From energetic point of view, O atom escapes from the lattice site more easily than Ga atom, thus forming a vacancy and an interstitial O atom. After relaxation, the interstitial Ga/O atom or anti-site defect forms a dumbbell configuration with the neighboring Ga/O atom and the surrounding atoms escape from the initial sites. In addition, existence of a Ga/O vacancy would reduce the formation energy of a new O/Ga vacancy. Both n-type and p-type conduction behaviors have been achieved in Si, Ge, Sn, P, Cl, and N doped β-Ga2O3, where the rarely observed p-type material was obtained by N dopants. However, we have also found that p-type N doped β-Ga2O3 would transform into n-type semiconductor by introducing oxygen/gallium vacancy defects. The atomistic insight into defect stability and electronic structures from the present study is beneficial for fabrication of β-Ga2O3 based semiconductor devices.