Auger electron spectroscopy study of the surface composition of the lead-indium system

Abstract

The Auger spectra of lead‐indium alloys (4.53, 9.08, 28.63, 44.62, and 60.49 atom% lead) and of pure lead and indium were monitored in the liquid and solid states. The relative intensities of the lead 92 eV and the indium 403 eV Auger peaks were used to determine the surface composition. The peak intensity ratio proved to be a sensitive detector of the change of surface composition with respect to temperature and bulk composition. The surface layers of the alloys were richer in lead than the bulk, and the surface composition exhibits a temperature dependence similar to that predicted by the ideal monolayer model. Oxygen decreased while carbon increased the surface excess lead concentration. Ion bombardment at 300°K caused appreciable solid state diffusion. This effect was considerably reduced by lowering the temperature to 78°K; however, selective removal of Pb then took place. Auger electron spectroscopy, when coupled with suitable calibration of the peak intensities, should be an excellent technique to study the surface thermodynamics of multicomponent systems.