Ion beam mixed tellurium Ohmic contacts to n-GaAs

The formation of Ohmic contracts to n-GaAs relies on the incorporation of suitable n-type dopants such as Ge, Te, or In at the GaAs surface. Several methods of alloying are used to form the Ohmic contacts. These include furnace and rapid thermal or scanned electron beam alloying. In this paper, results on the formation of Ohmic contacts using ion beam mixing technique are reported. They indicate that the degradation of the Ohmic contacts is due to the combination of both out-diffusion of Te into Au overlayer as well as the in-diffusion of Au into the underlying GaAs substrate. A better stability of Ohmic contacts formed by ion beam mixing at higher doses was obtained, due to a heavier incorporation of Te into GaAs than when low ionizing radiation was used. 4 refs., 3 figs