The electronic energy loss of 100 keV heavy ions in medium energy ion scattering analysis of a Ta₂O₅ ultrathin film

To optimize the depth resolution of Medium Energy Ion Scattering Spectroscopy (MEIS), a 10 nm Ta₂O₅ thin film on a Si(100) substrate was analyzed by MEIS using H⁺ and heavy ions such as Li⁺, N⁺ and Ne⁺ ions. The use of heavy ions such as Li⁺ and N⁺ increased the electronic stopping powers 2-3 times but it also increased the electronic straggling compared to H⁺ ions. For Ne⁺ ions, the ion neutralization problem was so severe that the scattering ion intensity from the subsurface layer was attenuated very rapidly and a strong doubly ionized Ne⁺⁺ peak was observed. For 100 keV N⁺ and Ne⁺ ions, multiple scattering peaks were observed.