Widely used metallization schemes for alloyed contacts to n‐type GaAs consist of a Au–Ge alloy with a cover layer of Ni or Pt. We have studied the interaction of these elements (Au–Ge and Ni, Au–Ge and Pt) upon heat treatment on an inert substrate. Our results show that Ni and Pt play an active role in contact formation. During heat treatment the Ge diffuses out of the Au into the Ni or Pt layer, respectively, where it forms stable compounds. Due to the fact that Ni and Pt act as a sink for Ge the composition and, as it is shown, the uniformity of the heat‐treated layers depend on the ratio of the amount of evaporated Ge to Ni or to Pt
