Size effects of epitaxial and polycrystalline Pb(Zr, Ti)O3 thin films grown by metalorganic chemical vapor deposition

In order to distinguish the dependence of electrical properties on thickness from that on grain size, the crystalline and electrical properties of epitaxial and polycrystalline Pb(Zr, Ti)O-3 (PZT) thin films grown on SrRuO3 (SRO)/SrTiO3(100) and SRO/SiO2/Si by metalorganic chemical vapor deposition (MOCVD) were investigated. The tetragonality of our epitaxial PZT films slightly increased with decreasing thickness. Relative dielectric constant(epsilon r()) of PZT films decreased with decreasing thickness. The thickness dependence of epsilon(r) was stronger for polycrystalline PZT thin films than for epitaxial films. The remanent polarization of both epitaxial and polycrystalline films was not dependent on thickness. The coercive field of both epitaxial and polycrystalline films increased markedly as the thickness decreased. In our experiment, the minimum thickness of epitaxial PZT films which showed D-E hysteresis was 40 nm.