Ferroelectric properties of an epitaxial lead zirconate titanate thin film deposited by a hydrothermal method below the Curie temperature

Abstract

Deposition of a hydrothermal method has a number of advantages; low deposition temperature, high-purity, deposition on a three-dimensional structure, and a large thickness. The present paper investigates the improvement of an epitaxial lead zirconate titanate (PZT) thin film deposited via hydrothermal synthesis. The critical parameter contributing to the film morphology was revealed to be the holding position of the reaction solution during deposition. In addition to this improvement, the SrRuO3 bottom electrode was confirmed to be able to withstand high alkali concentrations during the hydrothermal reaction. A hydrothermal synthesis time of 24 h yielded a PZT film with a thickness of 500 nm on SrRuO3/SrTiO3 (100) at 150 °C. The remanent polarization 2Pr and coercive electric field were 38.4 μC/cm2 and 21.8 kV/cm, respectively.

A Hydrothermally Deposited Epitaxial PbTiO3 Thin Film on SrRuO3 Bottom Electrode for the Ferroelectric Ultra-High Density Storage Medium

“…This is thought to be related to the lattice mismatching to the substrate, because in the PZT film the a-lattice constant was larger than the substrate, whereas that of lead titanate was smaller than the substrate. FIGURE 4 Hysteresis curves for PZT thin films deposited on SrRuO 3 /SrTiO 3 (100) [14].…”

“…The hydrothermal reaction conditions for epitaxial lead titanate thin film were modified from those for PZT deposition, as listed in Table I. An asreceived SrTiO 3 substrate was used as the substrate for the PZT deposition in the previous study [14]. This substrate had no atomic step surface.…”

“…Atomic force microscope observation revealed an atomic step of 0.4 nm at the SrTiO 3 substrate surface. A 50 nm thick epitaxial SrRuO 3 film was RF magnetron sputtered on this substrate as a bottom electrode [14,23]. Before applying SrRuO 3 /SrTiO 3 , we used Nb doped SrTiO 3 substrate to provide conductivity as a bottom electrode for PZT deposition, although measured DE hysteresis curve had been strongly distorted.…”

“…The remanent polarization for lead titanate was predicted to be 81 µC/cm 2 [9] and thus far, very little experimental data has been provided for this fundamental value, with the exception of that reported by Tabata [10]. The hydrothermal method [11][12][13][14][15][16][17][18], in contrast to the other methods, enables the deposition of a perovskite thin film in aqueous solution at very low temperatures, typically 100-200…”

“…Morita et al recently modified Chien's process [12] and measured the DE hysteresis properties of a hydrothermally deposited PZT film using a SrRuO 3 bottom electrode [14] on (100) SrTiO 3 single crystal. It was the first measurement results about the DE hysteresis curve of the hydrothermally deposited epitaxial ferroelectric thin films.…”