P-type conduction in ZnO thin films was realized by Al-N co-doping method. ZnO thin films were prepared in NH3-O-2 atmosphere with the substrate temperature in the range of 360-600degreesC with a 20degreesC space. The conduction type of Al-N co-doped ZnO thin films are dependant greatly on the growth temperature. With Al and N co-doping 1017 3 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 on sapphire substrate. Secondary ion mass spectroscopy (SIMS) tests proved that the presence of Al facilitated the incorporation of N into ZnO. A model showing nitrogen and aluminium incorparation suggests the difficultv of realizing p-type ZnO thin films of both high hole concentration and low resistivity by the Al-N co-doping method. X-ray diffraction (XRD) measurements showed that crystillinity of the Al-N co-doped ZnO thin films are also very dependant on the substrate temperature. (C) 2004 Elsevier B.V. All rights reserved.