Based on the criteria for the solid-state exchange reaction with p-GaN, we have investigated the intermetallic compounds, Pt3In7 and NiIn, as possible ohmic contacts. The as-deposited contacts were found to be rectifying and using current–voltage characterization rapid thermal annealing of the contacts was shown to significantly decrease their resistance, with contacts annealed at 800 °C for 1 min yielding the lowest resistance. Pt3In7 contacts to p-GaN when annealed at 800 °C for 1 min exhibited a specific contact resistance (ρc) of 9.5×10-2Ω cm2 while NiIn was more than an order of magnitude lower at 8.0×10-3Ω cm2. The NiIn contacts also show a lower specific contact resistance than the more traditionally used Ni/Au contacts (ρc=1.3×10-2Ω cm2) processed under the same conditions. Atomic force microscopy was used to examine the morphology of the reacted contacts. While the Ni/Au contacts showed the formation of deep spikes (≪200 nm) after annealing the NiIn contact showed a much smoother reaction region with no evidence of spiking. © 1999 American Institute of Physics.