Effects of niobium doping on microstructures and ferroelectric properties of bismuth titanate ferroelectric thin films

Bi4Ti3O12 thin films doped with 3 mol.% niobium were prepared on Pt/Ti/SiO2/Si substrates by sol-gel method. The niobium-doped Bi4Ti3O12 (Nb-BiTiO) films annealed at 700 deg. C for 30 min in oxygen showed randomly oriented layered perovskite structures and was composed of plate-like and rod-like grains with no crack. The remanent polarization (2Pr) and coercive field (2Ec) of the Nb-BiTiO film annealed at 700 deg. C were 28 μC/cm2 and 110 kV/cm, respectively. In addition, the film showed good switching endurance under bipolar pulse at least up to 4.5x1010 cycles. Substitution of Nb in BiTiO thin films was effective for reducing the oxygen vacancies and generating good ferroelectric properties