MICROSTRUCTURE, COMPOSITION, AND OPTICAL-PROPERTIES OF PBTIO3 THIN-FILMS PREPARED BY THE SOL-GEL METHOD

Crack-free and transparent PbTiO3 thin films with a perovskite structu re were deposited on NaCl (100), Si(lll), and fused quartz substrates by the sol-gel method. The crystal structure, morphology, domain struc ture, composition, and optical properties of the films were characteri zed by means of x-ray diffraction, transmission electron microscopy, s canning electron microscopy, x-ray photoelectron spectroscopy (XPS), a nd optical transmission spectrum. The films on Si and fused quartz sub strates exhibit slight a axis preferred orientation, while the films o n NaCl substrates show slight c axis preferred orientation. From XPS a nalysis, no residual carbon or other impurity element was detected on the films after 3 keV Ar+ cleaning. The chemical composition of the fi lms was found to be stoichiometric. A great amount of absorbed oxygen exists on the surfaces of the films. In the fine-grained (approximate to 150 nm) films, no 90 degrees domains are present in most of the gra ins, while some grains show lamellar 90 degrees domains. A large numbe r of pores exist in the films and their sizes are in the range of 5-30 nm. The packing density of the film fired at 600 degrees C was estima ted to be about 89.3% from its optical transmission spectrum. The film has a surface roughness Delta d approximate to 37.5 nm. The refractiv e index of the film is approximately 2.43 at 630 nm, and the absorptio n edge is at 321 nm. (C) 1997 American Vacuum Society.