Characterization of MOCVD PbTiO3thin films

Abstract

The metal-organic chemical vapor deposition (MOCVD) technique has excellent potential for the deposition of device-quality ferroelectric thin films. The MOCVD method has been applied to the preparation of perovskite PbTiO₃ thin films on fused silica and Pt-coated alumina substrates. An MOCVD system has been designed and built to deposit PbTiO₃ films starting from organic precursors (tetraethyl lead and titanium isopropoxide). A wide range of conditions were investigated, and the conditions suitable for the deposition of perovskite PbTiO₃ were identified. The stoichiometry of the PbTiO₃ films as determined by electron microprobe analysis was variable over a wide range, and two types of microstructures, either faceted or nodular were produced. When prepared under appropriate deposition conditions, the MOCVD PbTiO₃ films exhibited nominally phase-pure perovskite XRD patterns. However, the lattice parameters calculated by x-ray diffraction (a = 3.91 and c = 4.09 angstroms) indicated a slightly lesser degree of tetragonality in MOCVD PbTiO₃ than would be expected for bulk material. The MOCVD PbTiO₃ films also exhibited preferred crystallographic orientation, and this orientation was dependent on the deposition conditions.