Thermal stability of Pd/Pt/Au Ohmic contacts to InAlSb/InAs heterostructures for high electron mobility transistors

Abstract

We report the thermal stability of Pd/Pt/Au Ohmic contacts to InAlSb/InAs high electron mobility transistors. An initial drop in contact resistance correlates with consumption of the InAs electron channel through reaction of both Pd and Pt with the semiconductor heterostructure during a 3 h 175 °C anneal, as determined using transmission electron microscopy. Voids form in the unreacted Pt layer after samples are aged for 1 week at 175 °C, and they grow larger when the samples are aged for 1 week at 200 °C. The contact resistance increases by more than a factor of 2 after samples are aged for 1 week at 225 °C. We discuss the degradation of the contact resistance in light of the interfacial reactions that occur during aging.