Enhanced Spontaneous Polarization of Dysprosium-substituted Lead Zirconate Titanate Thin Films by a Chemical Solution Deposition Method

摘要

Influences of the B-site substitution using Dy~(3+) ion on the crystal structure and ferroelectric properties of lead zirconate titanate (PZT) films were investigated. Dy~(3+)-substiruted PZT films with nominal chemical compositions of Pb_(1.00)Dy_x(Zr_(0.40)Ti_(0.60))_(1-(3x/4))O_3 (x = 0 ～ 0.06) were fabricated by a chemical solution deposition (CSD). Polycrystalline PZT films with preferential orientation of (111)PZT were obtained on (111)Pt/TiO_2/SiO_2/(100)Si substrates, while epitaxially-grown (111)PZT films were fabricated on (111)SrRuO_3∥(111)Pt∥(100)YSZ∥(100)Si substrate. Ratio of PZT lattice parameters (c/a), which corresponds to its crystal anisotropy, was enhanced by the Dy~(3+)-substitution with x = 0.02. Spontaneous polarization (P_s) of Dy~(3+)-substituted PZT film (x = 0.02) along polar [001] axis of PZT lattice was estimated from saturation polarization (P_(sat)) value of the epitaxially-grown (111)PZT film on (111)SrRuO_3∥(111)Pt∥(100)YSZ∥(100)Si to be 84 μC/cm~2 that was significantly larger than that of non-substituted PZT (= 71 μC/cm~2). We concluded that the enhancement of P_s value could be achieved by the Dy~(3+)-substitution that promoted the crystal anisotropy of PZT lattice.