TREADS IN SURFACE ROUGHENING - ANALYSIS OF ION-SPUTTERED GAAS(110)

The effects of diffusion kinetics on surface roughness were investigat ed by measuring the dependence of surface width and step density on th e amount of material removed for GaAs(110) sputtered at different temp eratures (T). Surfaces after the removal of ten monolayers of material at 625 K were rougher on a small scale than those at 725 K, but they were smoother on a large scale. The increased large-scale roughness at high T was caused by increased diffusion on terraces and along step-e dges, but insufficient cross-step transport. The high step-density cre ated at low T enhanced cross-step transport. This mechanism, first pro posed for the re-entrant layer-by-layer growth, is expected to cause t he long-range roughness to increase with T for many solid surfaces aft er substantial sputtering or deposition over a certain range of T.