The annealing temperature dependence of contact resistance and layer stability of ZrB2/Ti/Au and Ni/Au/ZrB2/Ti/Au Ohmic contacts on p-GaN is reported. The as-deposited contacts are rectifying and transition to Ohmic behavior for annealing at >= 750 degrees C, a significant improvement in thermal stability compared to the conventional Ni/Au Ohmic contact on p-GaN, which is stable only to < 600 degrees C. A minimum specific contact resistance of similar to 2 x 10(-3) Omega cm(-2) was obtained for the ZrB2/Ti/Au after annealing at 800 degrees C while for Ni/Au/ZrB2/Ti/Au the minimum value was 10(-4) Omega cm(-2) at 900 degrees C. Auger Electron Spectroscopy profiling showed significant Ti, Ni and Zr out diffusion at 750 degrees C in the Ni/Au/ZrB2/Ti/Au while the Ti and Zr intertnix at 900 degrees C in the ZrB2/Ti/Au. These boride-based contacts show promise for contacts to p-GaN in high temperature applications. (c) 2006 Elsevier B.V. All rights reserved.