Experimental and theoretical studies of the energy-loss straggling of H and He ion beams in HfO2 films

We report an experimental-theoretical study of the energy-loss straggling of protons and alpha particles in HfO2 films. In the case of H ions the experiments were performed in the energy range 40-1750 keV. For the lower energy interval (40-250 keV) we have used the medium energy ion scattering (MEIS) technique with a resolution of Delta E/E similar to 4x10(-3), while for the higher energies the Rutherford backscattering technique (RBS) was employed with an overall resolution of 7 keV. Concerning the He ions the straggling study has covered an energy range between 250 and 3000 keV by using RBS measurements, which in this case had a resolution better than 10 keV. The theoretical calculations were done in the framework of the dielectric formalism using the MELF-GOS model to obtain a proper description of the energy loss function (ELF) of the HfO2 target. It is shown that for both projectiles the experimental data and the theoretical predictions for the energy-loss straggling display a very good agreement.