Minimization of topological defects in ion-induced ripple patterns on silicon

The evolution of self-organized nanoscale ripple patterns induced by low-energy ion sputtering of silicon is investigated. The quality of the patterns is monitored by calculating a normalized density of topological defects from atomic force microscopy images. A strong dependence of the normalized defect density on the applied ion fluence is observed with a well-pronounced minimum at intermediate fluences. Simulations using the damped Kuramoto-Sivashinsky equation yield good agreement with the experiments and are further used to study the dynamics of single pattern defects.