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O: Oberflächenphysik

O 11: Epitaxy and growth I

O 11.9: Vortrag

Montag, 27. März 2006, 17:00–17:15, WIL A317

Growth of different adatom systems on a Moiré superstructure induced by Pt deposition on WSe₂ — •Denys Makarov, Roger Pallesche, Günter Schatz, and Manfred Albrecht — University of Konstanz, Department of Physics, D-78457 Konstanz, Germany

The morphology and structure of Pt deposited on a WSe₂(0001) van der Waals surface was investigated by reflection high energy electron diffraction (RHEED) and compared to scanning tunneling microscopy (STM) and spectroscopy (STS). The growth of Pt at 450 ^∘C is characterized by an initial three-dimensional growth of (111)-orientated nanostructures followed by coalescence of the nanostructures. After a Pt thickness of about 3 nm a clear (4x4) superstructure appears, which is a result of strong Se diffusion towards the growth surface, forming most-likely a PtSe₂ alloy on the top surface. Due to the lattice mismatch between the Pt(111) layers and the PtSe₂ top layer a Moiré pattern is created. The investigation of the Pt growth on WSe₂ at different deposition temperatures shows that the Moiré structure is established at about 300 ^∘C. With the presence of the Moiré pattern the surface potential becomes a 2D periodical function of the local density of states near the Fermi level. Thus, the extrema of the local density of states can act as “pinning” sites for adatom nucleation. This approach for nanostructuring employing a self-organized Moiré pattern in the WSe₂/Pt system was attempted by the deposition of different adatom systems including metals (Co, Cr) and organic molecules (C₆₀).