Influences of Zn and Mn ions co-dopants on the optical and ferroelectric properties of BaTiO ₃ thin films

Zn-Mn co-doped BaTiO ₃ films were fabricated on Si (100) and LNO/Si (100) substrates by a sol-gel procedure. In order to study the effects of different doping levels on the microstructure and ferroelectric phase of BaTiO ₃ thin films, -BTO films doped with Zn and Mn, respectively, were also investigated. Both the characterization of X-ray diffraction (XRD) and atomic force microscope (AFM) indicate uniform and dense films with average grain size under 30 nm. By comparisons of the optical constant refractive index and extinction coefficient of BaTiO ₃ films in the wavelength from 400 nm to 700 nm, it was obtained that there is a change in the optical band gap due to the different amount of Zn and Mn added. Furthermore, a better defined P-E loop with a remnant polarization of 11.26 μC/cm ² shows that Zn and Mn dopanting play an essential role in ferroelectric improvement.