STM INVESTIGATION OF 2-DIMENSIONAL 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 tunnel ing 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 confi rm that both silicides are terminated by a Si bilayer without vacancie s. In the 3D case the outermost Si atoms exhibit an additional small b uckling with root 3 x root 3R30 degrees periodicity. The STM data impl y a specific registry of the surface Si layer with respect to the vaca ncy net underneath which is found to be in nice agreement with the sym metry of the dangling bond states at <(Gamma)over bar> observed in pol arization dependent photoemission.