Effects of surface roughness on results in elastic recoil detection measurements

In order to study surface roughness effects on the elastic recoil detection analysis series of stainless steel samples were prepared to four different roughnesses by wet grinding and polishing. A multilayer film of B + C (20 nm thick)/Ti (220 nm)/B + C (20 nm) was electron beam evaporated on stainle ss steel samples and a flat silicon wafer. The time-of-flight elastic recoi l detection analysis method utilizing a 53 MeV I-127(10+) beam was used to measure energy spectra of the recoiling sample elements. The topography of the samples was determined by atomic force microscopy and the film thicknes s by Rutherford backscattering spectrometry. A Monte Carlo simulation program which uses a measured surface structure an d takes fully account of multiple scattering was written to simulate the el astic recoil measurements. Effects observed in the experimental energy spec tra, like broadening of the peaks of deep lying layers, were reproduced in the simulations. Multiple scattering is the dominant factor behind the broa dening for flat surfaces. It enhances strongly also the broadening due to t he surface roughness. (C) 2000 Elsevier Science B.V. All rights reserved.