The Kinetic Effects of Layering Sequence of Al-Ge-Ni Ohmic Contact Components on (001) GaAs

Abstract

ABSTRACTElectrical characterization has demonstrated dramatic differences in the amount of heat treatment time required to convert the ohmic contact metallizations from Schottky to ohmic behavior, depending on the layering sequence of the Al, Ge, and Ni metals. Additional time differences were found to be dependent on the doping concentration of the contact layer of the GaAs and on the heat treatment temperature. For samples with Ge at the metal-semiconductor interface, the time required to convert from Schottky to ohmic behavior varies inversely with the doping concentration of the contact layer and directly with heat treatment temperature. Samples with Ni at the metal-semiconductor interface converted from Schottky to ohmic behavior much faster and had a much smaller dependence on the doping concentration and the heat treatment temperature. Models to explain these observations in terms of interdiffusion of the components and phases formed will be proposed.