Role of electronic excitations in the energy loss of H2+ projectiles in high-κ materials

Abstract

In the present work we report on the energy loss ratio Rn of fast H2+ clusters in thin films (30–50 Å) of LaScO3 and HfO2. The medium energy ion scattering technique was employed covering a broad energy range (40–200 keV/amu). The energy loss ratio data showed no clear evidence of collective excitations in these materials. The experimental results were interpreted in terms of three different theoretical approaches: the dielectric formalism with the Brandt-Reinheimer theory for semiconductor materials; the detailed simulation of the molecular fragments dynamics through the target; and finally the unitary convolution approximation adapted for hydrogen molecules. Only the simulation agrees with the experimental results for both oxides. The unitary convolution approximation works quite well for HfO2 but overestimates slightly the LaScO3 data. The overall results indicate that the energy loss ratio depends critically on the description of the electronic properties of such oxides.