Ab initio study of N-doped β-Ga 2 O 3 with intrinsic defects: the structural, electronic and optical properties

Abstract

Abstract We investigated the compensation mechanism between N acceptors and native defects in β-Ga 2 O 3 by employing the approach of pseudopotential plane-wave under the density functional theory framework. Four types of defect complexes: N Ga2O3 V O (N-doped β-Ga 2 O 3 with O vacancy), N Ga2O3 V Ga (N-doped β-Ga 2 O 3 with Ga vacancy), N Ga2O3 Ga i (N-doped β-Ga 2 O 3 with Ga interstitial), and N Ga2O3 O i (N-doped β-Ga 2 O 3 with O interstitial) are take into consideration. The electronic structures, formation energies, structural, and optical properties of the defect complexes are calculated. The calculated results indicate that N dopant acts as a deep acceptor with an acceptor level at 1.33 eV above the valence band maximum, which cannot be an effective P-type dopant. The formation energies of defect complexes N Ga2O3 V O and N Ga2O3 Ga i under Ga-rich atmosphere condition are 2.06 eV and 2.07 eV, respectively, which are close to the value of N Ga2O3 (1.90 eV) and indicate these two defect complexes are stable under Ga-rich atmosphere. Compensated by these two native defects, N-doped β-Ga 2 O 3 converts into weak n-type conductivity. After N-doped, a slight red-shift appears in the intrinsic absorption edge. When the intrinsic defects introduced, all the other defect complexes models induce a red-shift of the optical absorption edge compared with the pure β-Ga 2 O 3 except for N Ga2O3 Ga i .