Mn clusters on Si(1Â 1Â 1) surface: STM investigation

Using scanning tunneling microscopy (STM), the early stages of the Mn/Si(1 1 1) interface formation upon annealing of 0.05-0.30 ML of Mn at 320-550 °C have been studied. It has been found that depending on the growth conditions several kinds of clusters develop at the surface, including “large” clusters 50-115 Å in size and “small” clusters, which occupy single 7 × 7 unit cell halves. Two kinds of the “small” clusters have been distinguished. These are pyramidal clusters built of ∼10 Mn atoms and Mn-ring-clusters, which are seen in the empty-state STM images as a group of six protrusions forming a ring with a diameter of ∼7 Å and a center at the on-top site. The structural properties of the “small” clusters are discussed in some detail.