Photoluminescence in heavily doped ZnO:N:In films

Temperature-dependent photoluminescence is used to investigate ZnO films codoped with In and N at different doping levels. Conversion from exciton recombination to band-to-band transition with increasing both doping level and temperature is observed. We suggest that ionization of the N acceptors and dissociation of excitons by impurity-induced local field are responsible for such conversion. For the film with N concentration of 4 x 10(20) cm(-3), the excitonic emission intensity shows anomalous temperature dependence due to localized carriers. The localization energy and the N acceptor level is determined to be about 5 and 164 meV, respectively. (C) 2008 American Institute of Physics.