By combined investigation of STM and synchrotron PES on Ge/Si(5 5 12)-(2 x 1) at 530C, it was found that, in addition to the upward-relaxed surface Si atoms, a sub-surface Si atom was also readily replaced by an arriving Ge atom at the initial adsorption stage. Such enhanced interdiffusion was due to a unique character of one-dimensional chain structures of the reconstructed substrate, such as π-bonded and honeycomb chains not existing on other low-index Si surfaces such as Si(001)-c(4 x 2) and Si(111)-(7 x 7), applying a tensile surface stress to the neighbouring sub-surface atoms. Interdiffusion of Ge having lower surface energy induced adsorption of the displaced Si atoms on the surface to form sawtooth-like facets composed of (113)/(335) and (113)/(112) with arriving Ge atoms until the surface was filled with those facets. Such displacive adsorption was the origin of high Si concentration of formed facets.

Origin of Enhanced Ge Interdiffusion at the Initial Stage of Ge Deposition on Si(5 5 12)-2 x 1: Tensile Stress Induced by Substrate Chain Structures. H.Kim, O.Dugerjav, G.Duvjir, H.Li, J.M.Seo: Surface Science, 2012, 606[7-8], 744-8