Regensburg 2013 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 35: Poster Session I (Metal, semiconductor and oxide substrates: structure and adsorbates; Graphene)
O 35.38: Poster
Dienstag, 12. März 2013, 18:15–21:45, Poster B1
Epitaxial growth of Fe on Ag(001) revisited: Film stress measurements as a monitor of interface formation — •Kenia N. Fischer1,2, Dirk Sander1, Andre A. Pasa2, and Jürgen Kirschner1 — 1Max-Planck-Institut für Mikrostrukturphysik, Halle, Germany — 2LFFS, Universidade Federal de Santa Catarina , Florianópolis, Brazil
The growth of Fe on Ag(001) has created a lot of controversy regarding the growth mode in the first monolayers [1]. Early studies reported layer-by-layer growth up to 3 layers, whereas careful LEED studies [1] and EXAFS studies [2] ruled that out. Instead, surface alloying and a rough surface morphology were proposed for the first layers of Fe. Our measurements of Fe-induced film stress on Ag(001) show a nonmonotonic change of stress in the first layers. A surprisingly large tensile stress of +7.3 GPa is observed for the first 0.5 ML Fe deposition, which is followed by a compressive stress of -0.73 GPa from 0.5 to 1.5 ML. Then a tensile stress sets in, which leads to an average film stress of +2 GPa in a 10 ML Fe film. The magnitude of stress and its change of sign come as a surprise. The epitaxial misfit of +0.8 % leads to a calculated misfit stress of +1.7 GPa, in contrast to our observations. The observed stress variations in the monolayer range cannot be ascribed to simple layer-by-layer growth of an epitaxially strained Fe film. Rather, intermixing and surface stress change of the substrate upon film deposition need to be considered [3]. [1] Li et al., Phys. Rev. B 42(1990)9195. [2] Hahlin et al, Phys. Rev. B 73(2006)134423. [3] Mahesh et al., Phys. Rev. B 68(2003)045416.