SOL-GEL PROCESSING OF PZT THIN-FILMS - A REVIEW OF THE STATE-OF-THE-ART AND PROCESS OPTIMIZATION STRATEGIES

Sol-gel processing has been widely employed for the fabrication of lead zirconate titanate (PZT) thin films. To successfully optimize thin film material properties for different applications, we must develop a fundamental understanding of the processing-property relationships inherent in the sol-gel fabrication process. In the as-prepared state, sol-gel thin films are amorphous, have large organic contents, and can possess significant porosity. The preparation of thin films with acceptable properties requires that we effectively control densification and crystallization of the as-deposited film. We have determined that this ''structural evolution'' into the dense, crystalline ceramic phase may be affected by many aspects of the preparation process. In this paper we review the effects that tailored solution precursor characteristics and heat-treatment ramp rate can have on structural evolution. Specific examples are presented for process variation effects on the densification of thin films in the model system, ZrO2, and for the effects of controlled nucleation behavior on the optical scattering losses of PZT 40/60 thin films. Optimization strategies for sol-gel synthesis are also considered.