Temporal evolution of a silicon surface subject to low energy ion irradiation and concurrent sample rotation

We study the temporal evolution of silicon surfaces subject to low energy Ar+-ion bombardment and concurrent sample rotation. Systematic experiments are carried out in both the linear and nonlinear regimes. It is observed that an experiment which produces an anisotropic surface without sample rotation produces a statistically isotropic surface with a smaller surface roughness if the sample is rotated at a sufficiently high angular speed. Interrupted coarsening of the nanoscale mounds on the surface at long times t is observed without concurrent deposition of metal impurities for the first time. We find that the characteristic lateral size and height of the mounds increase as t1/2 and t, respectively. Both our experiments and simulations show that azimuthally rotating ripples form at a sufficiently small rotational speeds, as predicted two decades ago. Finally, predictions from theories on rotating samples subject to ion bombardment are tested.