Epitaxial Growth and Ferroelectric Properties of PbTiO3 Nanoislands and Thin Films Grown on Single-Crystalline Pt Films

概要

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Single-crystalline Pt (SC-Pt) films 15–60 nm thick with an atomically flat surface were coherently grown on SrTiO3(100) substrates by rf magnetron sputtering using Ir buffer layers. In the epitaxial growth of PbTiO3 films on SC-Pt films by metalorganic chemical vapor deposition, square nanoislands with heights of 3–30 nm and widths of 30–200 nm were grown by self-assembly at the initial growth stage, and subsequently, a continuous film was formed, indicating the Volmer–Weber growth mode. The minimum thickness required to form a continuous PbTiO3 film on SC-Pt films was 50 nm, which is much smaller than the 100 nm thickness on partially relaxed Pt films. Piezoresponse force microscopy revealed that piezoelectric constants of PbTiO3 nanoislands with heights below 10 nm were distinctly dependent on the height rather than the aspect ratio, suggesting intrinsic size effects of the piezoelectric constant. Continuous PbTiO3 films with thicknesses down to 50 nm exhibited saturated hysteresis loops with remanent polarizations of 57–64 μC/cm2 and coercive fields of 166–275 kV/cm.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2008-09-25