Structure of initial Ge nanoclusters at the edges of Si(1 1 1) steps with the front in the 〈−1 −1 2〉 direction

Initial stages of the formation of Ge nanoclusters at the edges of steps in the case of the deviation of Si(1 1 1) surface in 〈−1 −1 2〉 direction were studied with the help of ultrahigh vacuum scanning tunneling microscopy under the quasi-equilibrium growth conditions. On the basis of the analysis of the surface images with atomic resolution, the sequence of structural changes at the edges of steps during the initial formation of Ge nanoclusters was established. The atomic model of the stable initial nanoclusters in the half of unit cell of increased size of the surface structure 9×9 was proposed. Features of the atomic structure affecting the transfer of adsorbed atoms across the step were discussed.