SOS Simulation of Sputtered Nanoripples

摘要

We report a Monte-Carlo simulation of nanostructures that self-organize on surfaces under oblique ion bombardment. We have developed a quantitative solid-on-solid (SOS) model that describes the surface morphology during ion bombardment and performed the first systematic investigation for Cu bombarded by 1000 eV Ar~+ ions at 0°-80° incidence. When the angle of ion incidence exceeds ～40°, we observe 2-5 nm wide ripples aligned parallel to the ion beam plane in agreement with existing analytic theory. We also detect ripples directed perpendicularly to the ion beam plane, but the conditions under which they arise disagree with the theory. We have investigated the effect of surface relaxation on the morphologies and found two different regimes of ripple evolution depending on the efficiency of relaxation. After ～100 nm are removed, secondary 10-50 nm wide patterns are formed provided that relaxation is sufficiently high. We compare our simulations with those from other authors and with experiments.