Stable Schottky Contacts to n-Type GaAs Produced by Ge Rich Co-Ge Metalization

Abstract

Interfacial reactions between thin films of cobalt and germanium on (001) oriented GaAs substrates were studied in two configurations, Co/Ge/GaAs and Ge/Co/GaAs, with emphasis on Ge rich stoichiometries. It was found that at low temperatures, 250≤T<350δC, cobalt reacted with germanium to form intermetallie compounds which depended on the Co/Ge atomic ratio, while the inner interface with the GaAs substrate remained intact. At higher temperatures (up to 600δC) a limited reaction with the GaAs substrate was detected. This reaction was contained for both configurations near the interface with the substrate, and did not develop with temperature. The extent of reaction decreased with the decrease in the Co:Ge atomic ratio. Contacts produced in these systems were rectifying with a nearly ideal thermionic emission behavior.