AES study of room temperature oxygen interaction with near noble metal-silicon compound surfaces

Abstract We have carried out a comparative study of room temperature (RT) oxidation of near noble metal silicides similar in stoichiometry (M 2 Si) and electronic structure. Core-valence-valence (CVV) Auger line measurements on Ni 2 Si, Pd 2 Si and Pt 2 Si surfaces before and after exposure to 10 4 L of oxygen were performed. We compare the results with those for the oxidation of pure Si. In general oxygen interacts with Si atoms only. In Ni 2 Si, however, features ascribed to the onset of oxidation of Ni atoms appear in the Ni(MVV) line. In the Ni 2 Si and Pd 2 Si case, the Si reaction rate is increased with respect to that of pure Si, the strongest oxidation enhancement being obtained in Ni 2 Si. However, Si cannot be oxidized to SiO 2 in these conditions; a SiO x ( x 2 Si oxidation behaviour is close to that of pure Si. The different catalytic effect of Ni, Pd and Pt on Si oxidation has been discussed. We conclude that the main effect of metal is to by-pass the kinetic bottleneck of pure Si oxidation, i.e. the dissociation of the O 2 molecule at the silicide/gas interface. The effect of different exposure procedures was also underlined.