Discrepancy between ambient annealing and H+ implantation in optical absorption of ZnO

The discrepancy between sub-bandgap absorption in ZnO induced by thermal annealing and H + implantation is investigated in this study for the first time. Results indicate that nonreductive annealing-induced optical absorption is independent of annealing ambient, and can be assigned to V O , whereas the absorption centers caused by H + implantation and H 2 annealing are primarily associated with V O and ionized Zn i .