Oxygen diffusion analysis in transition metal oxides by Low Energy Ion Scattering

The understanding of oxygen interaction and diffusion in ultrathin oxide films is of great importance for their use in many applications, such as electronic devices and protective layers of extreme ultraviolet optics. In this work, we analyse oxygen diffusion in ultrathin oxide films through isotope exchange depth profiling (IEDP) with low energy ion scattering (LEIS). The high sensitivity of LEIS allows quasi-static measurements, where there is no influence of ion damage. LEIS also has good sensitivity to mass differences, which enables the correlation of isotope exchange kinetics at surfaces and in-depth penetration with high accuracy of atomic concentrations. This method was used to study atomic O exposure of films of ZrO2 and MoO3 of 2 nm to 10 nm, which were reactively deposited via DC magnetron sputtering. The diffusion profiles indicate a higher diffusion constant in the outermost monolayers of the oxide film, which may be caused by presence of oxygen vacancies in the film.