The electronic stopping powers and angular energy-loss dependence of helium and lithium ions in the silicon crystal

We have measured the electronic stopping powers of helium and lithium ions in the channelling direction of the Si < 100 > crystal. The energy range used (2.0-8.0 MeV) was changed by 200 and 400-keV steps. The ratio a between the channelling and random stopping powers was determined as a function of the angle for 2, 3 and 4 MeV He-4(+) ions and for 3 and 6 MeV Li-7(+.2+) ions. The measurements were carried out using the Rutherford backscattering spectrometry in the channelling mode (RBS-C) in a silicon-on-insulator material. The experimental channelling stopping-power values measured in the channelling direction were then discussed in the frame of the random energy stopping predictions calculated using SRIM-2013 code and the theoretical unitary convolution approximation (UCA) model. The experimental channelling stopping-power values decrease with increasing ion energy. The stopping-power difference between channelled and randomly moving ions increases with the enhanced initial ion energy. The ratio between the channelling and random ion stopping powers alpha as a function of the ion beam incoming angle for 2, 3 and 4 MeV He+ ions and for 3 and 6 MeV Li+.2+ ions was observed in the range 0.5-1. (c) 2017 Elsevier B.V. All rights reserved.