Dresden 2014 – scientific programme

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O: Fachverband Oberflächenphysik

O 95: Micro- and Nanopatterning (DS jointly with O)

O 95.1: Talk

Friday, April 4, 2014, 09:30–09:45, CHE 89

Effect of periodic pre-patterned structures on ripple wavelength and propagation velocity on ion-irradiated surfaces — •Detlef Kramczynski¹, Bernhard Reuscher², and Hubert Gnaser^{1, 2} — ¹Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, 67663 Kaiserslautern, Germany — ²Institute for Surface and Thin-Film Analysis (IFOS), 67663 Kaiserslautern, Germany

Glass surfaces were patterned by milling periodic trench structures with wavelengths from 150 to 750 nm in a focused ion beam (FIB) system. Upon exposure to 30 keV Ga⁺ ion irradiation under an incidence angle of 52^∘ with respect to the surface normal, these patterns were found to transform into "ripple"-like nanostructures. Their evolution was monitored in situ for ion fluences up to 2.5 × 10¹⁸ Ga⁺ ions/cm² using the scanning electron microscope incorporated in the FIB. With increasing fluence, the wavelengths of the ripples were found to stay constant (and equal to their original feature size) while they propagate across the surface, in a direction which coincides with the projection of the ion beam’s incident direction onto the surface. The propagation velocity was determined to scale inversely proportional to the wavelength, being in the range (60-100) nm/(10¹⁷ ions/cm²). On pristine surface areas (which had not been pre-patterned) ripples were also formed by ion bombardment. However, their wavelength was found to increase with ion fluence from initially ∼250 nm to ∼420 nm.