Interaction of zinc interstitial with oxygen vacancy in zinc oxide: An origin of n-type doping

Interaction of a zinc interstitial (Zni) with an oxygen vacancy (VO) was investigated to understand an origin of natively n-type characteristics of ZnO using density functional theory with the hybrid functional. The VO–Zni complex is formed with a formation of 3.82 eV and is a shallow donor with +1 charge state near the conduction band minimum. Its formation energy, however, is not low enough to be stable thermodynamically. Energy barrier for Zni migration in the VO–Zni complex is studied to consider its existence from kinetic aspect, and a high value of 1.3 eV is obtained with the kick-out process. Therefore, the bound Zni to VO can exist and supply electrons for native n-type ZnO kinetically.