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

Interaction of a zinc interstitial (Zn-i) with an oxygen vacancy (V-O) was investigated to understand an origin of natively n-type characteristics of ZnO using density functional theory with the hybrid functional. The V-O-Zn-i 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 Zn-i migration in the V-O-Zn-i 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 Zn-i to V-O can exist and supply electrons for native n-type ZnO kinetically. (C) 2012 Elsevier Ltd. All rights reserved.