Thermally grown SiO 2 film standards for elastic recoil detection analysis

Abstract

Thin-film SiO 2 Si structures, prepared by wet oxidation of (111)Si wafers have been investigated as reference standards for establishment of the energy and mass scales as well as the energy dependence of the detection efficiency in elastic recoil detection analysis (ERDA). 48 MeV 81Br 81+ ion incident 67.5° to the surface normal at fluences up to 2 × 10 14 ions cm −2 did not lead to statistically significant oxygen loss (< 5%) from the film nor to stoichiometry changes (< 5%). Furthermore no evidence of energy broadening due to surface charging was observed. The detection efficiencies of the recoil telescope were constant within ± 5% over the energy interval 9–12.7 MeV for 16O recoils and ± 3% over the interval 13–17.5 MeV for 28 Si recoils, respectively. The detection efficiency for 12.7 MeV 16O was 72% that of 17.5 MeV 28Si recoils. This efficiency variation may be associated with the dependence of the secondary electron yield on the electronic stopping in the carbon foil.