We have demonstrated the viability of depositing a thick Au bonding pad on top of Pt/Ti contacts on bothp‐InGaAs andn‐InP within a single evaporation prior to heat treatment. This eliminates the usual post‐sinter Au plating process. In particular, Au (500 nm)/Pt (60 nm)/Ti (50 nm) common contacts to Zn‐doped 5×1018cm−3p‐In0.53Ga0.47As and S‐doped 1×1018cm−3n‐InP were formed within a single pumpdown electron‐gun evaporation and subsequently a single sintering process by means of rapid thermal processing. The lowest resistivity of these ohmic contacts were found to be 0.11 and 0.13 &OHgr; mm (5.5×10−7and 8×10−6&OHgr; cm2) for thepandncontacts, respectively. These values were achieved as a result of heating at 450 °C for 30 sec. This heat treatment caused a limited reaction at the Au‐Pt and Pt‐Ti interfaces, which did not lead to any significant intermixing of the Ti and Au. Thus, no significant indiffusion of the Au thorough the Pt barrier was observed and contact degradation did not occur. The stress of the as‐deposited trilayer structure on InP was found to be 3×108dyne cm2tensile and increased to about 2×109dyn cm2as a result of the rapid thermal processing at 450 °C