Comparison between ruthenium-based and other ohmic contact systems to p-type GaAs

Abstract

A conventional furnace annealed Ru/Au ohmic contact system on p-GaAs has been investigated. Electrical and morphological characteristics of this contact system were compared with other systems such as Cr/Au, Ti/Pt, and Mn/Au. The Ru/Au contact system has been shown to have superior surface morphology and a comparable specific contact resistance value, even after annealing at 485°C. The advantages of utilizing Ru as contact material to GaAs are that it forms high quality, thermally stable Schottky contacts to n-GaAs and thermally stable ohmic contacts with low specific contact resistance to p-GaAs. This dual nature of Ru contacts to GaAs makes them extremely important for future use in devices such as heterojunction bipolar transistors (HBTs) and solid state lasers.