Berlin 2008 – scientific programme

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DS: Fachverband Dünne Schichten

DS 25: Trends in Ion Beam Technology: From the Fundamentals to the Application

DS 25.4: Talk

Thursday, February 28, 2008, 12:00–12:15, H 2013

Optical anisotropy induced by oblique incidence ion bombardment of Ag(001) — •Herbert Wormeester, Frank Everts, and Bene Poelsema — Solid State Physics, MESA+ Institute for Nanotechnology,

Oblique incidence ion sputtering has become a widely used method for the creation of highly regular patterns of lines and dots. On a Ag(001) surface oblique incidence sputtering creates a ripple pattern that exhibits plasmonic features. The photon energy of the plasmonic feature depends on the ripple periodicity. The development of these anisotropic features was measured in-situ with the optical technique Reflection Anisotropy Spectroscopy (RAS) for 2 keV Ar ions with a flux of a few µ A/cm² in a temperature range of 300 - 420K. With RAS, a periodicity of ripples above 200 nm is measured by a shift in photon energy of the plasmon resonance. Features with a smaller periodicity show a plasmon resonance around 3.65 eV. The Rayleigh-Rice description for scattering from a slightly rough surface enables to relate the measured plasmonic feature quantitatively to the ripple’s rms, wavelength and wavelength distribution. Ripple patterns created with ions at 70^∘ and 80^∘ polar angles of incidence are compared. High resolution LEED measurements after sputtering are used to determine the facet angles of the created ripples.