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O: Oberflächenphysik

O 19: Nanostrukturen II

O 19.7: Talk

Saturday, March 5, 2005, 12:15–12:30, TU EB420

Pattern defects and their effect on roughness in ion bombardement induced ripple formation — •Henri Hansen, Alex Redinger, Georgiana Stoian, Sebastian Messlinger, and Thomas Michely — I.Physikalisches Institut. RWTH Aachen. 52056 Aachen

Pattern formation by 5 keV Ar⁺ ion bombardement at an angle of 83^∘ with respect to the surface normal was studied in the temperature range from 250 K to 720 K.
The nature and density of defects in the ensuing ripple patterns was quantitatively analysed and correlated with the surface morphological evolution. For fixed fluence of 20 MLE a sudden increase in normalized defect density above 450 K is attributed to the onset of step edge diffusion, which tends to align ripple crests along <110 >-direction, whereas ion beam forces the ripple crests to orient along the <112>-direction. Defects in the pattern are spots of high local roughness and thus contribute significantly to the increase of pattern roughness above 450 K.