CHARACTERIZATION OF TEXTURE AND MICROSTRUCTURE OF ORIENTED PBTIO3 THIN-FILMS GROWN BY METALORGANIC CHEMICAL-VAPOR-DEPOSITION ON SI(100)

Oriented PbTiO3 (PT) thin films, approximately 2000 angstrom thick, ha ve been successfully grown on Si(100) using a low-pressure, cold-wall metalorganic chemical vapor deposition technique at temperatures as lo w as 450-degrees-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 s ource flow ratio and growth temperature is described. With proper grow th conditions, stocichiometric 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 Cur ie 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-degrees-C. It is hypot hesized 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 micro scopy showed visible grain boundaries for all crystalline samples, as well as the non-columnar cross-section morphology, which indicates hig hly dense and uniform structures. Using the transmission electron micr oscopy technique, these grains were found to consist of many fine crys talline particles (10-50 nm). Selected area electron diffraction patte rns from these crystalline particles have been indexed in terms of the tetragonal PbTiO3 phase.