Computer simulations of sputtering

Monte Carlo simulations have become a useful tool for studying ion radiation effects at or near surfaces or interfaces, such as sputtering, reflection, mixing, etc. The principal advantage of Monte Carlo calculations is that any physical process can be included directly. Also multielement and multilayer targets, even complex geometries, can be treated exactly in order to simulate realistic cases.The present paper will concentrate mainly on sputtering calculations with the Monte Carlo code TRIM, which treats ion and recoil transport in amorphous matter. It is based — as are analytic theories and most other Monte Carlo codes — on binary collisions with target atoms initially at rest. Over the past few years, the basic physical input has been greatly improved. Both the interatomic potentials and the electronic stopping powers proved to be of crucial importance even for the lowest energies occurring in recoil cascades. With the Kr-C or universal potential and the recent ZBL electronic stopping, which includes the Z oscillations, and a planar surface binding energy set equal to the heat of sublimation, realistic sputtering predictions could be obtained for most metals — without the use of any adjustable parameters.