Surface defects and bulk defect migration produced by ion bombardment of Si(001)

Variable-temperature scanning tunneling microscopy is used to characterize surface defects created by 4.5 keV He ion bombardment of Si(001) at 80-294 K; surface defects are created directly by ion bombardment and by diffusion of bulk defects to the surface. The heights and areal densities of adatoms , dimers. and adatom clusters at 80 and 130 K an approximately independent of temperature and in reasonable agreement with molecular dynamics calculat ions of adatom production. At 180 K, the areal density of these surface fea tures is enhanced by a factor of similar to 3. This experimental result is explained by the migration and surface trapping of bulk interstitials forme d within similar to 2 nm of the surface.