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O: Fachverband Oberflächenphysik

O 5: Adsorption on semiconductors, oxides and insulators I

O 5.9: Vortrag

Montag, 26. März 2012, 12:30–12:45, MA 042

Cu induced morphology changes at Pb/Si (111) interface: separation of "5x5"-Cu structure into individual domains. — •Pavel Shukrynau^1,2, Pingo Mutombo², Lars Smykalla¹, Vladimir Chab², and Michael Hietschold¹ — ¹Chemnitz University of Technology, Institute of Physics, Solid Surfaces Analysis Group. D-09107 Chemnitz, Germany. — ²Institute of Physics Academy of Sciences of the Czech Republic, Cukrovarnická 10. CZ 162 53 Prague, Czech Republic

The adsorption of small amount of Cu onto Pb covered Si (111-7x7 surface was studied with the variable temperature scanning tunnelling microscopy and spectroscopy. We observe many small clusters that appear on flat surface of 1x1-Pb islands upon RT deposition of copper. The behaviour of the clusters indicates that they are anchored to the underlying silicon substrate. Following temperature treatment fastens chemical reaction and transforms the clusters into shallow depressions of variable shape and size. Tunnelling spectra taken over the depressions suggest the formation of the copper silicides. Moreover, new objects having pronounced hexagonal form appear on rt3xrt3R30-Pb surface upon annealing. The filled and the empty state STM images of the hexagons differ strongly giving the evidence of an electronic effect. The hexagons are coalesced with the increase of Cu concentration and/or with the temperature rise. Detailed analysis of such agglomerate reveals hexagonal-like symmetry of pseudo-5x5 Cu structure. We suppose, that hexagonal objects are, possibly, individual "5x5"-Cu domains surrounded by the border made of Pb atoms.