Solid phase formation in Au: Ge/Ni,Ag/In/Ge,In/Au: Ge GaAs ohmic contact systems

Solid phase epitaxy formation in Au: Ge/Ni, Ag/In/Ge, and In/Au:Ge contacts to GaAs has been identified utilizing micro-spot Auger spectroscopy and selected area electron channeling. It is shown that the lateral extent of solid phase formation directly controls the value of the specific contact resistivity. Solid phase growth occurs as a result of dissolution of GaAs by the contact constituents in the vicinity of the eutectic temperature. Solid phase growth also results in regions free of oxide layers and contaminants and hence a lower contact resistivity.