IN-SITU ANNEALING STUDIES OF SOL-GEL FERROELECTRIC THIN-FILMS BY SPECTROSCOPIC ELLIPSOMETRY

Spectroscopic ellipsometry was utilized to follow in situ the annealin g of sol-gel Pb(Zr,Ti)O-3 films on sapphire and platinum-coated silico n substrates. Low-temperature processes, such as pyrolysis of organics and film densification, could be identified readily, Crystallization of the perovskite phase was initiated between 500 degrees and 600 degr ees C for the film on sapphire, This was coincident with the roughenin g of the film surface, Identification of higher-temperature processes in the film on platinum-coated silicon was complicated by temperature- dependent changes in the substrate, In situ annealing studies on the s ubstrate alone confirmed that, for the lengthy annealing profiles util ized in these experiments, substantial and irreversible changes in the effective substrate dielectric function occurred at temperatures >550 degrees C, In addition, the role of extended, high-temperature anneal ing on the optical frequency dielectric properties of the films was in vestigated.