Ir-based electrical contacts to p-type GaN have been fabricated and characterized. Both GaN//Ni/Au/Ir/Au and GaN//Ni/Ir/Au contact structures were deposited, however, only the former produced Ohmic current-voltage characteristics. At an anneal temperature of 500 degrees C, the Ni/Au/Ir/Au contact had a specific contact resistance of similar to 2 x 10(-4) Omega cm(2), comparable or superior to conventional Ni/Au contacts that are less thermally stable. Anneal temperatures above 500 degrees C caused the Ir-based contact to fail. Auger electron spectroscopy was used to obtain depth profiles of both types of contacts at a variety of temperatures in order to provide insight into the mechanism of Ohmic formation as well as potential reasons for failure. A comparison to other metallization schemes on p-GaN is also given. (C) 2008 Elsevier B.V. All rights reserved.