Regensburg 2007 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 5: Nanostructures at Surfaces I (Wires, Tubes)
O 5.4: Vortrag
Montag, 26. März 2007, 12:00–12:15, H36
Plasmon dispersion in dysprosium silicide nanowires — •Eddy Patrick Rugeramigabo1, Volkmar Zielasek2, and Herbert Pfnür1 — 1Institut für Festkörperphysik, Leibniz-Universität Hannover — 2Institut für Angewandte und Physikalische Chemie, Universität Bremen
By depositing Dy at around half monolayer coverage on single domain Si(001) surfaces miscut by 4∘ towards [110], we have grown DySi2 nanowires in the submonolayer regime. Their plasmon spectrum has been studied by a combination of high resolution EELS and spot profile analysis of LEED in one instrument (ELS-LEED) which enables us to measure characteristic losses with high momentum resolution. Ultraclean conditions (P≤ 1× 10−10 mbar during Dy deposition) allowed growth of high quality structures with minimal oxidation of Dy. Deposition of Dy at 500 ∘C results in the formation of single DySi2 nanowires on each terrace, leaving the periodicity of the clean Si surface unchanged. In contrast, deposition at room temperature and subsequent annealing to 500∘C reduces the average terrace width by up to 20%. Clearest results in EELS were obtained for a silicide layer with 0.4 ML of Dy deposited at 500∘C. Broad loss features in the range between 0 and 1 eV with typical dipole characteristics were detected, their position being strongly dependent on momentum transfer. As expected these characteristic losses have no dispersion normal to the wires, while parallel to the wires the dispersion is non-linear and goes to zero at zero momentum transfer. Thus the typical behavior of one-dimensional surface plasmons is found.