We report a shallow, thermally stable Pt/W/Au (2/50/145 nm) Ohmic contact to p-InGaSb prepared using a brief (NH4)(2)S rinse as part of the premetallization surface treatment. Cross-sectional transmission electron microscopy reveals that the Pt/W/Au contacts have better thermal stability than previously reported Pd/W/Au contacts, with the Pt/W/Au contacts remaining shallow even after they are aged at 250° C for 3 days. The specific contact resistances, of as-deposited Pt/W/Au, Pd/W/Au, Co/W/Au, Cu/W/Au, W/Au, Cr/W/Au, and Ag/W/Au contacts are also compared, and the (NH4) S rinse is found to partially relieve Fermi level pinning at the contact/p-InGaSb interface. © 2005 American Vacuum Society.