The occurrence of a diffusion-mediated chemical reaction in the layered structure, Co/Ge/Si(100), was reported. This led to the formation of Ge/CoSi2/Si(100). This was possible due to the lower onset temperature (about 150C) of inward Co diffusion in Ge(100), as compared to that (about 300C) in Si(100). The deposition of about 2 monolayers of Co at room temperature, onto a Ge-covered (3-monolayer) Si(100) surface, led to the formation of mainly Co-Ge species at the surface. However, upon annealing the sample at 400C, Co diffused through the Ge layer and reacted with Si to form a buried silicide: Ge/CoSi2/Si(100). The results suggested the possibility of fabricating heterostructures in a novel manner.

K.Prabhakaran, K.Sumitomo, T.Ogino: Applied Physics Letters, 1996, 68[9], 1241-3