Random energy loss and straggling study of 9 Be ions in silicon L.L. Araujo, M. Behar, P.L. Grande, J.F. Dias * Instituto de F  ısica, Universidade Federal do Rio Grande do Sul, Caixa Postal 15051, CEP 91501-970, Porto Alegre, RS, Brazil Abstract In the present work we have measured the random electronic stopping power and energy straggling of 9 Be in Si. In order to achieve this goal, we have employed the Rutherford backscattering technique together with a series of Bi markers implanted into Si. The stopping power measurements were performed in the 500–7000 keV energy range, while the energy straggling ones were done in the 800–5000 keV energy range. The results have been compared with the SRIM predictions and a quite good agreement is observed. Concerning the energy straggling, the experimental results are in general larger than predictions based on Bohr’s formalism, and only at higher energies (E P 3000 keV) the present results approach the Bohr values. Ó 2004 Elsevier B.V. All rights reserved. 1. Introduction The energy loss of light ions in materials is an important issue. This is not only because of its direct application in ion beam analysis but also in order to improve the understanding of funda- mental ion–solid interactions. Furthermore, for accurate ion beam analysis of elemental depth distributions in near surface layers, the stopping power of the respective ion-target combination must be known sufficiently well. The random stopping power is indeed well known for almost any H or He-target combination [1]. In particular, precise values for the stopping power of H, He, B and other light ions in amorphous Si have been already published [2–5]. These data are needed in order to test current theoretical calculation for the electronic energy loss and for analytic techniques such as elastic recoil detection analysis (ERDA) and heavy ion Rutherford backscattering (HIRBS) in order to perform precise energy to depth con- version. In the present work, we have measured random electronic stopping powers and energy straggling of 9 Be ions in Si. We have used the Rutherford backscattering technique (RBS) together with a series of Bi markers implanted into Si wafers. The advantage of this experimental arrangement is that it does not make use of thin selfsupported films as is the case for transmission measurements. Fur- thermore, this technique allows for stopping power and energy straggling measurements at quite low energies. Consequently, we were able to measure stopping powers over a wide energy range, be- tween 500 keV and 7 MeV, while we observed energy straggling over the 800 keV–5 MeV inter- val. The present results have been compared with * Corresponding author. Address: Laborat orio de Im- plantac ß~ ao I^ onica, Instituto de F  ısica – UFRGS, Av. Bento Gonc ßalves, 9500, CP 15051, Porto Alegre 91501-970, Brazil. Tel.: +55-51-3316-7248/7004; fax: +55-51-3316-7286. E-mail address: jfdias@if.ufrgs.br (J.F. Dias). 0168-583X/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.nimb.2004.01.062 Nuclear Instruments and Methods in Physics Research B xxx (2004) xxx–xxx www.elsevier.com/locate/nimb ARTICLE IN PRESS