CaBi 2 Ta 2 O 9 ferroelectric thin films prepared by pulsed laser deposition

Abstract

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 °C. The presence of (115) and (0010¯) orientations confirm the phase formation at the lower temperature (500 °C). Microstructure evolution of CBT films with oxygen pressure of 100–200 mTorr at a substrate temperature of 650 °C shows that the films deposited at lower pressure have a relatively smaller grain size and less surface roughness. The films grown at 650 °C exhibited a maximum polarization of (2Pm) 17 μC/cm2, remanent polarization of (2Pr) 8 μC/cm2 and coercive field of (Ec) 128 kV/cm, with fatigue endurance up to 1010 switching cycles. The higher dielectric constant (∼115 at 100 kHz) with a relatively lower dissipation factor (0.02) at higher growth temperature (700 °C) was explained by the increased grain size. The higher leakage current density (∼10−7 A/cm2) at higher deposition temperature is attributed to the interfacial diffusion of the film and the substrate.