Effect of amorphous TiO2 buffer layer on the phase formation of CaBi4Ti4O15 ferroelectric thin films

Amorphous buffer layers of TiO2 were introduced between CaBi4Ti4O15 thin films and Pt bottom electrodes through chemical solution deposition techniques. Several tens of nanometers thick alkoxy-derived TiO2 layers were found to be critical for acceleration of the phase transition in the thin films. Unlike thin film crystallized directly onto a highly (111) oriented Pt bottom electrode, the thin film on an amorphous TiO2 layer was almost single phase perovskite and showed random orientation. The crystallinity of the CaBi4Ti4O15 thin film was much higher than that crystallized directly onto the Pt bottom electrode. The dielectric and ferroelectric properties of the CaBi4Ti4O15/TiO2 stacked thin films on Pt coated Si substrates are evaluated, leading to the potential of the amorphous buffer layer for the integrated devices being clarified.