Berlin 2024 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 81: Nanostructures at Surfaces I

O 81.6: Vortrag

Donnerstag, 21. März 2024, 11:45–12:00, MA 042

Diffusion studies on Pb islands and on the wetting layer in Pb/Si(111)-(7x7) — •Paul Philip Schmidt, Felix Hartmann, Lea Faber, and Regina Hoffmann-Vogel — University of Potsdam, Institute of Physics and Astronomy, Germany

Metallic structures on semiconductors offer a wide range of technical applications. This presentation will focus on the diffusion behavior of Pb/Si(111)-(7x7). It is known that Pb initially forms a wetting layer on Si, from which islands then form. Previous research has shown that this system exhibits explosive island growth and abnormally fast diffusion [1][2]. In our study, we focus on the wetting layer. After fabricating the 7x7 reconstruction on Si(111) under ultra-high vacuum conditions, we evaporate between 2 and 7 monolayers Pb at substrate temperatures between 120 and 300K. The diffusion was studied using non-contact cantilever scanning force microcopy (NC-SFM) and simultaneous Kelvin probe force microscopy (KPFM). While the topographical data of the NC-SFM essentially confirmed known data on the growth of the islands, the KPFM showed changes in the local contact potential difference (LCPD). In one experiment, a local imbalance was additionally generated on an island by manipulating a Pb island using the SFM-tip. Despite the low time resolution of an SFM measurement, it was possible in this way to determine the time scales of the mass transport. [1] M. Hupalo et. al. Phys. Rev. B, 23 (2007) [2] K. L. Man et al. Phys. Rev. Lett., 101 (2008)

Keywords: KPFM; diffusion; wetting layer; island growth; Pb/Si(111)