ION-INDUCED EFFECTIVE SURFACE-DIFFUSION IN ION SPUTTERING

Ion bombardment is known to enhance surface diffusion and affect the s urface morphology. Here we demonstrate that preferential erosion durin g ion sputtering can lead to a physical phenomenon reminiscent of surf ace diffusion, what we call effective surface diffusion (ESD), that do es not imply mass transport along the surface and is independent of th e temperature. We calculate the ion-induced ESD constant and its depen dence on the ion energy, flux and angle of incidence, showing that spu ttering can both enhance and suppress surface diffusion. The influence of ion-induced ESD on ripple formation and roughening of ion-sputtere d surfaces is discussed and summarized in a morphological phase diagra m. (C) 1997 American Institute of Physics. [S0003-6951(97)02245-6].