Study of pulsed laser ablated CaBi₂Ta₂O₉ thin films

Abstract

Polycrystalline CaBi₂Ta₂O₉ thin films were grown on Pt/TiO₂/SiO₂/Si (100) substrates using a pulsed laser deposition technique. The influence of substrate temperature and oxygen pressure on crystallization and orientation of the films was studied. In-situ films deposited under a combination of higher substrate temperature and lower oxygen pressure exhibited a preferred c-axis orientation. Micro-Raman spectroscopy was used for complete understanding of phase evolution of CBT films. Thin films deposited at higher substrate temperatures showed larger grain size and higher surface roughness, observed by atomic force microscopy. The values of maximum polarization (2P_m~13.4 µ C/cm²), remanent polarization (2P_r~4.6 µ C/cm²) and the coercive field E_c was about 112 kV/cm obtained for the film deposited at 650° C and annealed at 750° C. The room temperature, dielectric data revealed a dependence on the grain size.