A theoretical-experimental straggling study of H ions into HfO2 films

Paper submitted to the 9th International Conference on Applications of Nuclear Techniques, Crete, Greece, 8–14 June 2008.We present an experimental study of the energy-loss straggling of protons into HfO2 films, as well as a comparison with the theoretical predictions of the MELF-GOS model. The experiments were performed using a H beam provided by a 3 MV Tandetron accelerator in an energy range between 40 and 2000 keV. The targets were HfO2 films with thicknesses of 40, 60, 80, 100 and 150 nm. We have used nuclear reaction analysis (NRA) and Rutherford backscattering (RBS) techniques with a Si barrier detector, having a resolution of 7 keV. By comparing the front and back edge of the RBS spectra we extract the corresponding energy loss straggling values for each one of the energies we have studied. The calculations were done in the framework of the dielectric formalism, paying especial attention to a proper description of the Energy Loss Function (ELF) of the HfO2 targets, which accounts for the electronic excitations produced in the material by the passage of a charged projectile. The experimental data and the theoretical results of the energy-loss straggling of swift H beams in HfO2 films show a very good agreement.Work financially supported by the Spanish Ministerio de Educación y Ciencia (Projects Nos. FIS2006-13309-C02-01 and FIS2006-13309-C02-02). CDD thanks the Spanish Ministerio de Educación y Ciencia and Generalitat Valenciana for support under the Ramón y Cajal Program