Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 5: Adsorption on semiconductors, oxides and insulators I
O 5.11: Vortrag
Montag, 26. März 2012, 13:00–13:15, MA 042
Interaction of Ta with Si (100) surface: Intermixing at the interface. — •Pavel Shukrynau1,2, Pingo Mutombo2, Lars Smykalla1, 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 amounts of tantalum on Si (100)-2x1 reconstructed surface was investigated systematically using scanning tunneling microscopy/spectroscopy combined with first-principles density functional calculations. We found that the room temperature deposition of Ta on to Si (100)-2x1 surface followed by moderate annealing results in the formation of the short nanochains running perpendicular to the silicon dimer rows of the substrate. The chains are sporadically distributed over the surface and their density is metal coverage dependent. Filled and empty state images of the chains differ strongly giving the existence of covalent bonds within a particular chain. Careful analysis of these images allowed us to build up several structural models. Simulating the STM images on the base of these models and consequently comparing them with experiment, one of the proposed geometries is confirmed to match best the Ta chains. Tunneling spectra taken over each individual protrusion within a chain reveal small energy gap, showing semiconductor-like behavior of constituent atoms.