Correlation between the 3.31-eV emission and the doping level in indium-doped ZnO nanostructures

The origin of the 3.31-eV emission in ZnO materials is still controversial so far. We report the 3.31-eV emission in In-doped ZnO nanostructures. A direct correlation between the intensity of the 3.31-eV peak and the In content is observed in both the photoluminescence (PL) and PL excitation spectra. Temperature-dependent PL reveals that the 3.31-eV emission at low temperatures is due to donor–acceptor pair recombination, with an acceptor level of 114 meV. We suggest that such an acceptor level is likely related to stacking faults induced by In doping.