Confined Ni film on a Pd/Si(111)-(root 3 x root 3)R30 degrees surface: spatially resolved XPS study of the surface reactions

We used scanning photoelectron microscopy with lateral resolution of 0.15 m u m to study the interactions of a (root 3 x root 3)R30 degrees-Pd/Si(111) surface with a rectangular 2 ML Ni film deposited at 300 K and after stepwi se annealing to 1120 K. The evolution in the surface composition and electr onic structure inside, outside and across the edge of the Ni film was exami ned by mapping the lateral changes of the valence band, Ni 3p. Si 2p and Pd 3d core levels. The results showed that up to 780 K the changes at both in terfaces are determined by temperature-induced interactions leading to form ation of new silicide phases. Edge effects at the forefront of the patch ar e identified and the composition of microscopic three-dimensional silicide islands formed after annealing to 1120 K is determined as well. (C) 2000 El sevier Science B.V. All rights reserved.