Characterization of texture and microstructure of oriented PbTiO3 thin films grown by metalorganic chemical vapor deposition on Si(100)

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Abstract
Oriented PbTiO3 (PT) thin films, approximately 2000 Å thick, have been successfully grown on Si(100) using a low‐pressure, cold‐wall metalorganic chemical vapor deposition technique at temperatures as low as 450 °C. Titanium isopropoxide, Ti(C3H7O)4, tetraethyl lead, Pb(C2H5)4, and pure oxygen were used as precursor materials in this work. The dependence of film texture and microstructure on the Pb/Ti source flow ratio and growth temperature is described. With proper growth conditions, stoichiometric PbTiO3 films can be produced. Two types of polycrystalline PbTiO3 films, including multi‐oriented and single‐oriented textures, were obtained. At growth temperatures above the Curie point (cubic‐to‐tetragonal transition temperature), multi‐oriented textures were found. On the other hand, oriented films were fabricated at growth temperatures in the range of 450–475 °C. It is hypothesized that the preferred orientation is due to the combined effects of thermal stress and anisotropic growth rates along different crystal directions. Microstructure examinations using scanning electron microscopy showed visible grain boundaries for all crystalline samples, as well as the non‐columnar cross‐section morphology, which indicates highly dense and uniform structures. Using the transmission electron microscopy technique, these grains were found to consist of many fine crystalline particles (10–50 nm). Selected area electron diffraction patterns from these crystalline particles have been indexed in terms of the tetragonal PbTiO3 phase.