STM investigation of 2- and 3-dimensional Er disilicide grown epitaxially on Si(111)

The surface atomic structure of 2- and 3-dimensional (D) Er disilicide epitaxially grown on Si(111) has been investigated by scanning tunneling microscopy (STM) and angle-resolved photoemission. The STM images reveal that highly ordered 2D and 3D silicide islands can be grown on the flat Si(111)7x7 terraces and atomic resolution scans clearly confirm that both silicides are terminated by a Si bilayer without vacancies. In the 3D case the outermost Si atoms exhibit an additional small buckling with root 3 x root 3R30 degrees periodicity. The STM data imply a specific registry of the surface Si layer with respect to the vacancy net underneath which is found to be in nice agreement with the symmetry of the dangling bond states at <(Gamma)over bar> observed in polarization dependent photoemission.