Anzenberg, EitanMadi, Charbel S.Aziz, MichaelLudwig, Karl F. Jr.2014-08-262011Anzenberg, Eitan, Charbel S. Madi, Michael J. Aziz, and Karl F. Ludwig Jr. 2011. “Time-Resolved Measurements of Nanoscale Surface Pattern Formation Kinetics in Two Dimensions on Ion-Irradiated Si.” Physics Review B 84, no. 21: 214108.1098-0121http://nrs.harvard.edu/urn-3:HUL.InstRepos:12748665The nanoscale kinetics of surface topography evolution on silicon surfaces irradiated with 1 keV Ar+ ions is examined in both directions perpendicular and parallel to the projection of the ion beam on the surface. We use grazing incidence small angle x-ray scattering to measure in situ the evolution of surface morphology via the linear dispersion relation. We study the transition from surface ultra-smoothening at low angles of deviation from normal ion incidence to a pattern-forming instability at high incidence angles. A model based on the effects of impact-induced redistribution of those atoms that are not sputtered away explains both the observed ultra-smoothening at low angles from normal ion incidence and the instability at higher angles and accounts quantitatively for the measured two-dimensional dispersion relation and its dependence on incidence angle.en-USJournal Article2014-08-2610.1103/PhysRevB.84.214108