N-doped p-type ZnO (p similar to 10(18)cm-(3)) was grown on sapphire(0 0 0 1) substrate by metal-organic chemical vapor deposition method. Ni/Au metal was evaporated on the ZnO film to form contacts. As-deposited contacts were rectifying while ohmic behavior was achieved after thermally annealing the contacts in nitrogen environment. Specific contact resistance was determined by circular transmission line method and a minimum specific contact resistance of 8 x 10(4)Omega cm(2) was obtained for the sample annealed at 650 degrees C for 30 s. However, Hall effect measurements indicate that, as the rapid thermal annealing temperature increased up to 550 degrees C or higher the samples' conductive type have changed from p-type to n-type, which may be due to the instability nature of the present-day p-type N-doped ZnO or the dissociation of ZnO caused by annealing process in N-2 ambient. Evolution of the sample's electric characteristics and the increment of metal/semiconductor interface states induced by rapid thermal annealing process are supposed to be responsible for the improvement of electrical properties of Au/Ni/ZnO. (C) 2008 Elsevier B. V. All rights reserved.