The Al-N co-doped p-type ZnO thin films have been prepared by direct current magnetron reactive sputtering. Second ion mass spectroscopy tests proved that incorporation of Al facilitated N solution into ZnO, which promotes the formation of p-type conduction. With Al and N co-doping technique, we have observed a room temperature resistivity of 24.5 Omega cm and a hole concentration of 7.48 x 10(17) cm(-3) in ZnO thin films. A conversion from n-type conduction to p-type in a range of temperatures has been identified by the measurement of Hall effect and Spreading Resistance Profiles. X-ray diffraction measurements showed that the crystalinity of the Al-N co-doped ZnO thin films are also very dependent on the substrate temperature. (c) 2005 Elsevier B.V. All rights reserved.