Low-resistance Pd/Ir/Au ohmic contacts on p-GaAsSb

Ohmic contacts based on Pd/Ir/Au metallisations have been formed on highly doped (5*10/sup 19/ cm/sup -3/) p-type GaAsSb. Typical hole mobility in the MOCVD-grown p-GaAsSb was measured to be 50 cm/sup 2//Vs. Electrical characteristics of ohmic contacts were measured utilising the transfer length method. The ohmic contact exhibited specific contact resistivity less than 10/sup -8/ (Omega)-cm/sup 2/ and transfer length less than 100 nm. X-ray photoelectron spectroscopy study was also utilised to investigate the interactions between the multilayer metallisations and the ternary GaAsSb compound semiconductor.