In-situ post deposition annealing of lead-free ferroelectric thin films in oxygen rich atmosphere

Nano-sized ferroelectric Ba(Zr_0.15Ti_0.85)O₃ (BZT) thin films were deposited on Pt/Ti/SiO₂/Si<111> substrates using pulsed LASER deposition technique. X-ray diffraction results highlighted the formation of single phase perovskite structure and Atomic Force Microscopy analyses revealed the uniform distribution of the nanometer sized grains. Enhanced properties were observed by in situ annealing of deposited BZT thin films in oxygen rich environment. The observed values of saturation polarization, remanent polarization are several orders higher than those reported in literature. The possible mechanisms for enhanced properties were discussed. Annealing in oxygen rich atmosphere decreased oxygen vacancies which in turn helped in realizing high dielectric constant and better tunability. A low leakage current density was observed in 125 nm thick BZT films. The underlying transport mechanism of leakage current was found to be of Poole–Frenkel type, an interface related phenomenon. Tunability as high as 62 % was observed corresponding to in situ annealed thin films.