Synchrotron radiation photoemission study of the formation of the Ag/GaSb(110) interface

Abstract

We have studied the chemistry and electronic properties of the Ag/GaSb(110) interface formed at room and low temperature with high resolution core level photoemission spectroscopy. The Ga 3d and Sb 4d core level spectra are deconvolved into bulk, surface, and reacted components. The relative changes in intensities of these components as a function of Ag coverage at room temperature (RT) and low temperature (LT) are studied in terms of interface morphology and chemistry. At LT, the Ga 3d and Sb 4d surface components disappear with about one monolayer of Ag coverage, confirming the two dimensional Ag growth. At RT, on the other hand, the surface components persist up to coverages of several monolayers, indicating a Volmer–Weber growth mode. At higher coverages, both the Ga 3d and the Sb 4d spectra are dominated by reacted components with lower binding energy. The intensity of the Ga 3d core level decays faster as a function of Ag coverage than that of Sb 4d, indicating out diffusion of Sb. Out diffusion is reduced at 80 K. Band bending at the GaSb surface is extracted from the shift of the bulk components. The final position of EF is found to be within 50 meV of the valence band maximum, in good agreement with previous ultraviolet photoemission results.