Photoluminescence study of interstitial oxygen defects in ZnO nanostructures

ZnO defect luminescence is a fascinating but still highly controversial issue. Herein, the role of interstitial oxygen played on the photoluminescence (PL) property of ZnO nanostructures is investigated through oxygen plasma exposure and low temperature O2 annealing. In contrast to previous reports, no interstitial oxygen related deep level emission was observed in PL spectra from room temperature (RT) to 7 K after oxygen-rich treatments, except apparent suppression of the exciton emission due to the upward band bending effect. This work illustrates that the isolated interstitial oxygen seems not to cause the widely reported yellow/orange emission regardless of the ZnO growth method.