Producing virtually defect-free nanoscale ripples by ion bombardment of rocked solid surfaces

Bombardment of a solid surface with a broad, obliquely incident ion beam frequently produces nanoscale surface ripples. The primary obstacle that prevents the adoption of ion bombardment as a nanofabrication tool is the high density of defects in the patterns that are typically formed. Our simulations indicate that ion bombardment can produce nearly defect-free ripples on the surface of an elemental solid if the sample is concurrently and periodically rocked about an axis orthogonal to the surface normal and the incident beam direction. We also investigate the conditions necessary for rocking to produce highly ordered ripples and discuss how the results of our simulations can be reproduced experimentally. Finally, our simulations show that periodic temporal oscillations of coefficients in the Kuramoto-Sivashinsky equation can suppress spatiotemporal chaos and lead to patterns with a high degree of order.