Investigation of oxygen defects in wurtzite InN by using density functional theory

Density Functional Theory based on ab initio calculations was employed to investigate single and complex defects of oxygen in indium nitride and their influence on the optical properties. Different oxygen contents (x=1.38%, 4.16%, 5.55% and 11.11%) were considered in our study by using PBEsol-GGA and TB-mBJ for the treatment of exchange-correlation energy and potential. It was found that oxygen is energetically favorable to exist mainly as singly charged isolated defect. The results using TB-mBJ approximation predicts a narrowing of the VBM (valence band maximum) and CBM (conduction band minimum) as oxygen content increases. Nevertheless, the larger contribution of the Moss-Burstein effect leads to an effective band-gap increase, yielding absorption edge values larger than that of the intrinsic bulk indium nitride.