CaBi2Ta2O9 ferroelectric thin films prepared by pulsed laser deposition

Thin films of CaBi2Ta2O9 (CBT) were deposited on Pt/TiO2/SiO2/Si substrates using the pulsed laser deposition technique at temperatures ranging from 500 to 700 degreesC. The presence of (115) and (0010) orientations confirm the phase formation at the lower temperature (500 degreesC). Microstructure evolution of CBT films with oxygen pressure of 100-200 mTorr at a substrate temperature of 650 degreesC shows that the films deposited at lower pressure have a relatively smaller grain size and less surface roughness. The films grown at 650 degreesC exhibited a maximum polarization of (2P(m)) 17 muC/cm(2), remanent polarization of (2P(r)) 8 muC/cm(2) and coercive field of (E-c) 128 kV/cm, with fatigue endurance up to 10(10) switching cycles. The higher dielectric constant (similar to 115 at 100 kHz) with a relatively lower dissipation factor (0.02) at higher growth temperature (700 degreesC) was explained by the increased grain size. The higher leakage current density (similar to 10(-7) A/cm(2)) at higher deposition temperature is attributed to the interfacial diffusion of the film and the substrate. (C) 2001 American Institute of Physics.