In this study, Al-doped ZnO (AZO) and Ni/AZO films were deposited on p-type GaN films followed by thermal annealing to form ohmic contacts. After thermal annealing, the resistivities of AZO films reduced from 5x10(-3) to 4-6x10(-4) Omega cm. Both as-deposited AZO and Ni/AZO contacts on p-GaN displayed a non-ohmic characteristic. Only the 800 degrees C-annealed Ni/AZO contacts exhibited a linear current-voltage characteristic, showing a specific contact resistance of around 1.2x10(-2) Omega cm(2). After undergoing the annealing in nitrogen ambience, the light transmittance of the Ni/AZO films increased from 70% to higher than 90% in the visible range. These results revealed that the Ni/AZO contact can serve as a suitable transparent current spreading layer for the fabrication of GaN-based light-emitting devices.