Synchrotron-radiation photoemission studies of Cu/InSb(110) interface evolution and modification by Al interlayers

High-resolution synchrotron-radiation photoemission has been used to investigate room-temperature reactions and the atomic distributions at the Cu/InSb(110) interface with and without interlayers of Al. Our results show limited disruption of InSb upon Cu deposition and a strong tendency for In and, especially, Sb atoms to segregate to the surface region of the growing Cu-derived overlayer. Interlayers of Al alter the morphology of the overlayer and the atom distribution in a way which is related to the Al/InSb interface itself and the solubility of In and Sb in Cu. For submonolayer Al interlayers, Al acts as a reacted marker and has little impact on interface evolution. At intermediate Al coverage, Al/InSb reaction results in the release of In while at higher coverage, the reaction becomes diffusion limited, Al clustering occurs, and freed In segregates to the surface. Overlayers of Cu then trap a portion of the freed In, but have little effect on Sb, which continues to segregate. For thick overlayers of Cu, we observe In and, especially, Sb segregation to the surface.