  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 nano-fabrication 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.
