An experimental investigation of angular resolved energy distributions of atoms sputtered from evaporated aluminum films

A study of angular resolved velocity (energy) distributions of atoms sputte red from in situ prepared metal films is described in this contribution. Th e velocity resolution of the set-up is based on the pulsed laser-induced fl uorescence technique, i.e., scanning the narrow bandwidth dye laser radiati on over the Doppler broadened absorption profile of the sputtered particles . The arrangement of the vacuum vessel and fluorescence detection optics pr ovides the means for an independent selection of the observed emission dire ction and the angle of incidence. A pulsed ion gun is applied to bombard th e target with noble gas ions in the energy range between 200 and 500 eV. Th e target assembly allows the preparation of thin metal films by evaporation on optically polished glass substrates without break of the vacuum. We rep ort on measurements obtained with this arrangement, i.e., the determination of energy distributions of sputtered aluminum atoms. The bombardment at bo th the normal and the oblique incidence of the ion beam are contained in th e investigation. Pronounced anisotropic effects are observed in both cases. In the case of oblique bombardment the shape of the distributions reflects cascade effects as well as single collision properties. The energy distrib ution is approximated with the aid of an energy spectrum involving a superp osition of exponential functions. The experimental results are compared wit h simulations obtained by the Monte Carlo code TRIM.SP. (C) 2001 Elsevier S cience B.V. All rights reserved.