Energy Dependence ofHe+andH+Channeling in Si Overlaid with Au Films

Channeling measurements by backscattering of He and H ions have been made on $〈111〉$- and $〈110〉$-oriented Si covered with evaporated layers of Au to investigate the dependence of minimum yield on both energy and film thickness. The energy range was 0.4-1.8 MeV and the film thickness range was 100-1100 Å. Minimum yields are calculated by applying the Meyer treatment of plural scattering and probability curves determined from (i) a step-function approximation to the angular yield profile and (ii) two different axial scans on uncovered Si, one of which is azimuthally averaged. The minimum yields calculated using the step-function approximation and azimuthally averaged probability curves are in good agreement with experimental results. This suggests that the step-function approximation, although less accurate than the azimuthally averaged procedure, is adequate for use with investigations of disorder in crystals by channeling-effect measurements.