Palladium-promoted oxidation of Si at low temperatures

A palladium (Pd) layer deposited on the ultrathin silicon oxide-covered Si substrate promotes Si oxidation. Take-off angle dependent X-ray photoelectron spectroscopy (XPS) measurements and the capacitance-voltage measurements show that after the heat treatment of the 〈Pd/chemical oxide/Si(100)〉 specimens at 400°C in oxygen, the thickness of the oxide layer between the Pd layer and the Si substrate increases to 4-4.5 nm but no oxide is formed on the Pd surface. When the Pd layer is deposited on the hydrofluoric acid-etched Si surface, palladium silicide is formed, while no silicide is formed in cases where the Pd film is deposited on the thin chemical oxide covered-Si substrate. It is concluded that the diffusing and reaction species are oxygen atoms (or oxygen ions), initially formed at the Pd surface.