Core-level photoemission studies of the α-Sn/InSb(100) heterostructure system

Layers of gray tin (α-Sn) were grown epitaxially on InSb(100) substrates at room temperature. The two high-quality InSb(100) reconstructions, Sb-stabilized c(4 x 4) and In-stabilized c(8 x 2), were used for starting surfaces. Core-level photoemission and electron diffraction were used to study the development of the interface as a function of Sn coverage and to determine the discontinuity in the valence-band maximum. For both starting surfaces, there was evidence for some Sb segregation into the Sn films during the initial stages of interface formation; the c(4 x 4) surface showed an earlier onset for the segregation. The Sn growth was found to be fairly flat for the first two layers, and three dimensional after that. The final valence-band discontinuity was found to be the same for both the c(4 x 4) and the c(8 x 2) starting surfaces. This discontinuity was compared to present theoretical predictions