p-Type ZnO thin films with c-axis orientation have been prepared in N2O + O-2 atmosphere oil glass substrates by DC reactive magnetron sputtering, and with the Al+N-codoping technique, we have realized p-ZnO in the same conditions. Results showed that types of conduction and carrier density in codoped ZnO films were found to be dependent oil the substrate temperatures. At 500degreesC, both Al + N-codoped p-type ZnO films and N-doped ones have the highest hole density of 1.1 x 10(17) and 6.7 x 10(14) cm(-3), respectively. When the growth temperature is higher than 550degreesC, p-type ZnO films cannot be achieved using the Al + N-codoped method. It is difficult to achieve p-ZnO with both high hole concentration and high mobility by codoping, most likely due to the inherent defects of the AlN precipitates produced in codoping process. (C) 2004 Elsevier B.V. All rights reserved.