Dresden 2006 – scientific programme

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DS: Dünne Schichten

DS 20: Ion beam induced nanostructures

DS 20.1: Invited Talk

Thursday, March 30, 2006, 14:00–14:45, GER 37

Nanostructures by grazing incidence ions: ripple patterns, athermal coarsening and subsurface channeling — •Thomas Michely — I. Physikalisches Institut, RWTH Aachen, 52056 Aachen

The recent years showed significant progress in our ability to use ion beams for the controlled patterning of surfaces. New applications of such patterned substrates as functional surfaces or templates for subsequent growth of thin films emerge. Nevertheless, our present understanding of the atomic scale mechanisms governing pattern formation is still poor.

With the help of scanning tunneling microscopy investigations and molecular dynamics simulations a few steps towards a better understanding of metal surface patterning in the grazing incidence ion beam geometry could be made. Most surprising, pattern formation depends crucially on the angle of incidence of the ions. As soon as this angle allows subsurface channeling of the ions, pattern regularity and alignment with respect to the ion beam greatly improves. These effects rare traced back to the positionally aligned formation of vacancy islands through the damage created by the ions at dechanneling locations. The long term pattern evolution is characterized by a temperature independent increase of the ripple pattern wavelength. This coarsening is shown to be due to pattern defects, which travel in the ion beam direction and perform defect reactions.

The contributions of Henri Hansen, Alex Redinger, Sebastian Meßlinger, Yudi Rosandi and Herbert Urbassek to this work are acknowledged.