Sputtering yields, range and range straggling in Al following Kr+ ions bombardment in the energy range (20-160) keV

The sputtering of Al metallic films by Kr-84(+) ions has been studied over the energy range (20-160) keV. Sputtering yield data have been extracted by means of the Rutherford backscattering technique (RBS) using a 2 MeV beam of He-4(+) ions. They have been compared to values derived by Sigmund's linear cascade theory, Yamamura's semi-empirical formula or by Monte Carlo computer simulation using the TRIM code. A fair agreement was observed between the measured sputtering yields and the predicted ones. The depth profiles of the implanted Kr+ ions into Al have also been measured, and then fitted assuming Gaussian shape distributions, which allowed us to extract the projected range, R-p, and the associated range straggling, Delta R-p. For the former stopping parameter, a very good agreement is obtained between experiment and the LSS theory predictions while the MC simulation also accounts satisfactorily for the measured data over the whole explored energy range, reflecting an adequate description of the projectile-target interaction by the universal potential of the Thomas-Fermi type assumed in the LSS formalism. In contrast, the Delta R-p measured data show to be consistent with the predicted values only at E >= 60 keV but lie to similar to 30% above them at lower energies. This discrepancy not caused by the sputtering effect relates to an incomplete evaluation of the range straggling by theory at low bombarding energies. (c) 2005 Elsevier B.V. All rights reserved.