RBS SPECTRA FOR THIN-FILMS WITH SURFACE-ROUGHNESS

The effect of surface roughness of a random type on the RBS spectrum shape for thin films has been examined by computer simulation. The assumed surface roughness relief was obtained by a Monte Carlo technique using a pseudorandom discrete function with two parameters, viz. the standard deviation sigma in the relief height and the correlation length lambda. The model takes into account cases of multiple crossings of the surface by an outgoing ion. Numerical simulations of RBS deuteron yields from an iron oxide film have been made for normal incidence geometry. The dependence on the parameter lambda of the RBS spectrum deformation due to roughness has been derived.