Development of Thermally Stable Indium-Based Ohmic Contacts to N-Type GaAs

Abstract

ABSTRACTDevelopment of low resistance ohmic contacts to n-type GaAs which withstand high temperature cycles without degrading their electrical properties is crucial for fabrication of high performance GaAs integrated circuits. Prior to our work, indium-based ohmic contact materials were not attractive for actual devices, because the contacts provided resistances higher than those of the widely used AuNiGe contacts, were thermally unstable after contact formation, and had rough surface morphology. Recently, based on analysis of the interfacial microstructure of these contacts, several thermally stable, low resistance In-based ohmic contacts to n-type GaAs have been developed in our laboratories using a standard evaporation and lift-off technique and annealing by a rapid thermal annealing method. The present paper points out the reasons for the poor electrical properties and thermal stability of the “traditional” In-based ohmic contacts, and reviews the recent progress.