Microstructure development in lead zirconate titanate ferroelectric thin films during annealing

Lead zirconate titanate (PZT) thin films with a Zr/Ti ratio of 52/48 were prepared by a sol-gel method on platinized Si, (0001) sapphire, and (100) MgO substrates. The evolution in crystallinity was studied in real time during annealing with an in-situ X-ray diffraction system using a Ruud-Barrett Position sensitive Scintillation Detector (R-B PSSD). Annealing rates of 50/spl deg/C min/sup -1/ and 100/spl deg/C min/sup -1/ were utilized to study the growth of an intermediate fluorite or pyrochlore phase and the perovskite phase. This provided evidence on the structure evolution during heat treatment. It is also proposed in this study that spectroscopic ellipsometry (SE) be used to examine the microstructure evolution of PZT thin films during annealing. Changes in optical properties, i.e., the refractive index, as a function of temperature can be determined. Because the refractive index depends on the crystal phase, SE can serve as an indirect means of following the crystallization. The volume fraction of the crystalline phases, the film thickness, and the presence of the surface roughness can also be obtained from SE measurement.