Electrical and dielectric properties of low-temperature crystallized Sr0.8Bi2.6Ta2O9+x thin films on Ir/SiO2/Si substrates

Ferroelectric thin films of bismuth layer structured compounds, Sr0.8Bi2.6Ta2O9+x (SBT) were deposited onto Ir/SiO2/Si substrates using metal organic decomposition (MOD) method. The crystallization of the SBT thin films annealed at various temperatures was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The polarization (P) versus electric field (E) characteristics exhibited a systematic variation from linear to non-linear polarization (hysteresis) with an increase in the annealing temperature of the SBT films. The leakage current density and dielectric constant of the SBT films were also strongly dependent on the annealing temperature, which in turn determined the grain size, mean surface roughness and inter diffusion through interfacial layers. The lowest leakage current density of 10-9 A cm-2 at 100 kV cm-1 was obtained for SBT thin film annealed at 450 deg. C. The SBT thin films annealed at 650 and 700 deg. C remained fatigue-free up to 1011 switching cycles