Interfacial reactions between thin Co films and monocrystalline GaAs substrates were studied by using Auger electron spectroscopic, transmission electron microscopic, and X-ray diffraction methods. The interaction began at about 325C, with the formation of a ternary phase (probably Co2GaAs) which grew in a highly oriented manner with respect to the (001) substrate; with a lattice mismatch of about -10%. The reaction kinetics were studied and were found to be diffusion-controlled; with an activation energy of 0.7eV. The Co was deduced to be the predominant diffusing species. The oriented ternary phase coexisted with randomly oriented CoGa and CoAs at temperatures of between 325 and 500C while, at higher temperatures, only the binary compounds prevailed.

M.Genut, M.Eizenberg: Applied Physics Letters, 1987, 50[19], 1358-60