Exchange reaction, clustering, and surface segregation at the Al/InSb(110) interface

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Abstract
High-resolution photoemission studies of the Al 2p, In 4d, and Sb 4d core levels for the Al/InSb(110) interface have been performed. Detailed core-level line-shape analysis makes it possible to follow the growth and attenuation of each of the reacted species and to model the evolving morphology of the interface. These results show the onset of heterogeneous reaction at room temperature by a nominal coverage of 0.06 Å. By 3-Å nominal coverage, clusters of metallic Al have formed over the reacted region, indicating the self-limiting, localized character of the Al/InSb reaction, while lateral growth of the reacted region continues. With increasing coverage, the Al islands grow and small metallic clusters of In appear on the surface. At a nominal coverage of ∼20 Å, the reaction across the surface is complete, and the deposition of additional Al results in the growth of the large, sparsely distributed Al islands which do little to attenuate the substrate signal.