ANGULAR DISTRIBUTION OF BERYLLIUM SPUTTERED BY A KRYPTON

BEAM AT OBLIQUE INCIDENCE: EXPERIMENT AND SIMULATIONS

P.-G. Fournier1*, A. Nourtier2, V. I. Shulga3

1Laboratoire de Spectroscopie de Translation des Interactions Moléculaires,

Université Paris-Sud, Bât. 478, Orsay 91405 France

2Laboratoire de Physique des Solides, Université Paris-Sud, Bât. 510, Orsay 91405 France

3Institute of Nuclear Physics, Moscow State University, 119992 Moscow, Russian Federation

* Corresponding author . E-mail : paul-guy.fournier@stim.u-psud.fr

Received : 01 June 2004; revised version accepted : 28 June 2004

Abstract

A beryllium target is bombarded with 5 keV krypton ions at an incidence angle of 70°. The sputtered material is collected on a Mylar™ cylindrical foil surrounding the target, 70 pieces are cut out of the foil and the deposit on them is measured by inductively coupled plasma optical emission spectroscopy (ICP-OES). The experimental data are compared with simulations using the computer code OKSANA. Besides a formula based on a simple model is tested. The simulations agree with experiment quite well as much for the sputtering yield (between 10 and 10.8 atoms/ion from the simulations depending on the model, 9.8 ± 0.9 from experiment) as the overall angular distribution and the position of the peak at 31° from the normal in the forward direction. There are however two significant differences. First, a fraction of the sputtering product leaves the target as clusters which split in flight soon after emission. From the modification of the angular distribution this fraction is estimated to 5%. Second, lateral ejection is stronger in the experiment. This is explained by surface grooves parallel to the incidence plane, as revealed by scanning electron microscopy. In addition the sticking coefficient on the foil is shown to be practically unity.

Keywords: Surface; Sputtering; Angular distribution; Beryllium; Mylar™; Sticking; Roughness;

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