This study reports on the electrical and photoluminescent properties of Al-N co-doped ZnO films with different Al contents. The results suggest that N solubility in ZnO is limited even by the co-doping method. littermediate Al contents were found to be most important for achieving high-hole-concentration p-type ZnO. Carrier mobility was found to decrease with increasing Al content. Low temperature photoluminescence spectra revealed a dominant emission band at 3.13 eV, which was attributed to a DAP transition. The observed broadened and red-shifted DAP band in the high -Al-con taining co-doped samples could relate to rather potential fluctuations. (c) 2007 Elsevier B.V. All rights reserved.