Ferroelectric and optical properties of Bi3.25Nd0.75Ti3O12 thin films prepared by a chemical solution method

The ferroelectric and optical properties of Bi3.25Nd0.75Ti3O12 thin films deposited on (111)Pt/Ti/SiO2/Si substrates using a chemical solution method were investigated. Bi3.25Nd0.75Ti3O12 thin films were polycrystalline and had (117) random orientation with large rod-like grains. They showed good ferroelectricity with a remnant polarization of 13.8 muC cm-2 and a coercive field of 120 kV cm-1. The dielectric constant and the dissipation factor were about 200 and 0.040, respectively, at a frequency of 10 kHz. No polarization fatigue was observed for the Pt/Bi3.25Nd0.75Ti3O12/Pt capacitor after 109 switching cycles. The optical constants (refractive index and extinction coefficient) in the wavelength range of 200-1700 nm were obtained by spectroscopic ellipsometry measurements. The optical band gap was estimated to be about 3.61 eV. The dispersion of the refractive index in the interband transition region followed the single electronic oscillator model.