Low Temperature Heteroepitaxial Growth of a New Phase Lead Zirconate Titanate Film on Si Substrate with an Epitaxial (ZrO₂)_1-x(Y₂O₃)_xBuffer Layer

Abstract

We investigated the crystalline and electrical properties of heteroepitaxial lead zirconate titanate (PZT) films grown on Si covered with epitaxial (100) (ZrO 2 ) 1−x (Y 2 O 3 ) x (YSZ) buffer layers. The PZT films were prepared by reactive sputtering. When the substrate temperature was between 400 and 485 • C, we obtained a heteroepitaxial (110) oriented monoclinic PZT (m-PZT) film which was metastable. The lattice parameters were as follows: a = b = 0.379 nm, c = 0.521 nm and γ = 81.3 • . The m-PZT film had a larger oxygen composition ratio O/(Zr + Ti) of 3.2 to 3.8 than the perovskite phase. Although the resistivity of the as-grown m-PZT film was much lower than that of the normal perovskite phase, it was increased by two to five orders of magnitude by a step-annealing process of 300 • C for 120 min, 325 • C for 120 min and 350 • C for 180 min in sequence. From the C-V characteristics of the step-annealed m-PZT/YSZ/Si structure, the relative dielectric constant was estimated to be about 45.