Electron beam annealed Ge-WSi-Au and Ge-Ni-WSi-Au high temperature stable ohmic contacts on n-GaAs

Detailed analysis of electron beam annealed Ge-WSi-Au and Ge-Ni-WSi-Au ohmic contacts is reported. Lower contact resistance values with better reproducibility and much lower standard deviation are achieved with Ni doped TLM devices. Ar+ ion X-ray photoelectron depth profiling was used to relate the distribution of Ge, Ni, W, Si, Au, Ga and O to the electrical properties of contacts. Ohmic behaviour was found probably to be dependent upon the Ge and Ni compound formation on the GaAs surface.