Regensburg 2025 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 69: Nanostructures at Surfaces II
O 69.5: Vortrag
Mittwoch, 19. März 2025, 16:00–16:15, H25
Areas of lower local contact potential difference in the wetting layer in the system Pb/Si(111)-(7x7) — •Paul Philip Schmidt1, Felix Hartmann1, Ralf Metzler1,2, Janet Anders1,3, and Schmidt Hoffmann-Vogel1 — 1University of Potsdam, Institute of Physics and Astronomy, Germany — 2Asia Pacific Center for Theoretical Physics, Pohang 37673, Republic of Korea — 3Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 4QL, UK
The description of the diffusion of Pb atoms on Si(111)-(7x7) is highly non-trivial. Previous studies show that although Pb grows in the Stranski-Krastanov mode, it exhibits explosive island growth and ultrafast mass transport [1,2]. The developing wetting layer plays a special role [3]. We have investigated this system using non-contact scanning force microscopy and Kelvin probe force microscopy. We have worked under ultrahigh vaccum conditions at variable temperatures between 120K and 300K. Our studies show inhomogeneities of the work function in the wetting layer. The areas with different work function seem to be related to the position of the islands and the step edges of the Si(111). We assume that the different work function values are caused by different Pb concentrations in the wetting layer, which are probably related to the preferred direction of growth of the islands, so that in certain areas Pb is extracted from the wetting layer with varying effectiveness. [1] M. Hupalo et. al. Phys. Rev. B, 23 (2007), [2] K. L. Man et al. Phys. Rev. Lett., 101 (2008), [3] M. T. Hershberger et al. Phys. Rev. Lett. 113 (2014)
Keywords: Scanning Force Microscopy; Kelvin Probe Force Microscopy; Diffusion; Nucleation; Wetting Layer