ROUGHNESS STUDY OF ION-IRRADIATED SILICA GLASS-SURFACE

We have investigated the surface roughness of ion-irradiated silica gl ass by the use of atomic force microscopy (AFM). Highly polished synth etic silica glass was irradiated with 120 keV Ar+ ion at a dose range of 1 x 10(12)-1 x 10(17) ions/cm(2) The surface roughens progressively at an ion dose up to 1 x 10(14) ions/cm(2), whereas smoothing occurs at an ion dose above 1 x 10(14) ions/cm(2). The smoothing in the high dose region is attributed to the viscous relaxation induced by ion bea m. As to roughening in the low dose region, two mechanisms both sputte ring and compaction has been discussed. The roughening is thought of t he compaction of the partial region in which each of the ion impacts c ause structural changes.