Abstract
Effects of alkaline solution concentration and deposition temperature on the film thickness, crystal structure, and ferroelectric properties were investigated for epitaxial PbTiO3 films grown on (100)cSrRuO3//(100)SrTiO3 substrates by hydrothermal method. The (001)-oriented PbTiO3 films were grown at 150 °C with KOH solution concentrations from 1 to 10 mol/L. Potassium incorporation was not detected for the films deposited at 10 mol/L. c-axis lattice parameters continuously decreased with the increase in the KOH solution concentration. A 250-nm-thick film grown at 8 mol/L showed lattice parameters expected from bulk PbTiO3 and showed good ferroelectric properties; a remanent polarization and an average coercive field (average of plus and minus coercive field, Ec) of about 74 µC/cm2 and about 173 kV/cm, respectively. Film thickness was successfully increased by raising the deposition temperature to 200 °C at 8 mol/L. Lattice parameters were almost unchanged by changing the deposition temperature. The relationship between Ec and the film thickness (t) agreed with the semiempirical scaling law (Ec ∼ t−2/3). These data suggest that the increase in the deposition temperature is one of the effective ways to deposit thick PbTiO3 films.
