Diffusion of gold and platinum in amorphous silicon and germanium

195Au radiotracer atoms produced via the radioactive decay of implanted 195Hg ions have been used to investigate systematically the diffusivities of Au in amorphous Si and Ge by means of serial Ar+-beam sectioning as a function of the diffusion temperature, doping with Au and/or charging with hydrogen. Less extensive studies of the same type have been carried out for the diffusion of Pt in Pt-doped amorphous silicon. The Au diffusion data are interpreted in terms of direct diffusion in which the diffusing 195Au atoms are temporarily trapped by different kind of vacancy-like defects. These traps can be saturated with Au or hydrogen. Their nature and concentrations are found to change as a result of annealing-induced structural relaxation of the amorphous specimens.