Angular distribution of atoms sputtered from amorphous and polycrystalline targets

The angular distributions of atoms sputtered from amorphous and polycrystalline targets under 1 and 10 keV Ar ion bombardment (normal incidence) have been calculated using the binary-collision simulation. A large set of targets, from Li-3 to U-92, was considered. The distributions were approximated by a function cos(n) theta. It has been shown that the exponent n is by far not a universal target-independent constant. In case of amorphous targets, which have been considered in detail, the exponent can be approximated by n = 1 + AN(p)/U-q, N being the target atomic density, U the surface binding energy, A, p and q fitting parameters. For polycrystalline targets, a pronounced decrease of n is noted for the targets predisposed to the generation of focused collision sequences. In both cases, the exponent is strongly dependent on the interatomic potential used. Results are compared with data from the literature with special emphasis on sputtering from iron, platinum, gold and germanium. (C) 2000 Elsevier Science B.V. All rights reserved.