Formation of an amorphous Rh-Si alloy by interfacial reaction between amorphous Si and crystalline Rh thin films

Interfacial reaction in bilayers of amorphous Si and crystalline Rh thin films has been studied by transmission electron diffraction and microscopy. In a bilayer of ∼190-Å amorphous Si and ∼60-Å polycrystalline Rh films, we have observed the formation of an amorphous Rh-Si alloy film upon thermal annealing at 300°C. The amorphous alloy film crystallizes into the RhSi phase at 400°C. On the other hand, no amorphous alloy formation was observed upon annealing a bilayer of ∼150-Å amorphous Si and ∼100-Å polycrystalline Rh films; instead, they react at 300°C to form Rh2Si, followed by the formation of RhSi or a mixture of RhSi and Rh5Si3 around 400°C.