Channeling in Si Overlaid with Al and Au Films

Channeling measurements by backscattering of 1.8-MeV He ions have been made on $〈111〉$- and $〈110〉$-oriented Si covered with evaporated layers of Al and Au. The minimum yield, half-width of the angular-yield profile, and depth dependence of the aligned yield were measured as a function of metal-film thickness. Comparisons between experimental and calculated values have been made on the basis of two different treatments of plural scattering. The minimum yield follows the predictions of the Meyer treatment. This treatment leads to good agreement with angular-yield profiles and dechanneling dependence on depth obtained with Al films. For Au films the measurements suggest that the distribution should be more peaked than that calculated. These results can also be applied to investigations of dechanneling and disorder in single crystals.