High-energy ion beam analysis of ferroelectric thin films

Abstract

The composition and crystalline quality of ferroelectric thin films formed on Pt covered MgO(100) substrates have been investigated with combined use of 16O(α, α) 16O 3.045 MeV resonant backscattering and channelling techniques. Oxygen depth profiling has been estimated by the resonant backscattering, and crystalline quality was estimated by the channelling method. The ferroelectric thin films of PbTiO y (PTO) and La-modified PTO (Pb x La 1 − x TiO y ; PLT) ( y ≈ 3) of 750 Å thick were formed on Pt covered MgO substrates by multi-target ion beam sputtering method with introducing oxygen gas. Pt thin films beneath the film due to the under-electrode were also fabricated by the same method. For both PTO and PLT films, depth profiling of Pb and Ti elements showed relatively constant concentrations for whole film thicknesses, whereas the oxygen concentrations varied drastically. The extent of variation of oxygen concentration was larger for the PTO film than for the PLT film. This led to better crystalline quality of PLT, compared with PTO. The effect of oxygen depth profiling and crystalline quality on the electric properties is also discussed.