Reactivity of Intermetallic Thin Films Formed by the Surface Mediated Decomposition of Main Group Organometallic Compounds

We have observed that by the reaction of silane with clean Ni, Rh, Pt, Mo, Ta, W, Cu, and Au surfaces at elevated temperatures, thin alloy and intermetallic compound phases can be prepared. For example, SiH₄ reacts with atomically clean nickel surfaces to give a > 50 A surface film of predominantly Ni₂Si. Subsequent reaction with oxygen leads to the formation of a thin passivating layer of SiO₂; structurally similar materials were also obtained from the direct reaction of silane with oxidized nickel surfaces. Our results from studies on a wide variety of metal surfaces suggest a general procedure for the preparation of passivating, non-native oxide thin films. The scope of this methodology as regards applicable metals and reactive gases, and the physical and chemical properties of several representative materials is discussed.