Low temperature heteroepitaxial growth of a new phase lead zirconate titanate film on Si substrate with an epitaxial (ZrO2)(1-x)(Y2O3)(x) buffer layer

We investigated the crystalline and electrical properties of heteroepitaxia l lead zirconate titanate (PZT) films grown on Si covered with epitaxial (1 00) (ZrO2)(t-x)(Y2O3)(x) (YSZ) buffer layers. The PZT films were prepared b y reactive sputtering. When the substrate temperature: was between 400 and 485 degrees 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 gamma = 81.3 degrees. The m-PZT film had a larger oxygen composition ratio O/(Zr + Ti) of 3.2 to 3.8 than the perov skite phase. Although the resistivity of the as-grown m-PZT film was much l ower than that of the normal perovskite phase, it was increased by two to f ive orders of magnitude by a step-annealing process of 300 degrees C for 12 0 min, 325 degrees C for 120 min and 350 degrees 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.