THE STUDY ON FERROELECTRIC THIN FILM MATERIALS FOR NON-VOLATILE MEMORY

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Ferroelectric domain structures of tetragonal PZT ceramics were evaluated by the poling field (E) dependence of planar coupling factor (kp) and relative XRD intensity of (002) peak, I_<002>. We proposed typical domain configurations composed of 15 patterns. Furthermore, we picked out the two patterns to make a domain configuration model with 90ﾟ and 180ﾟ domains. It was thought that the change in the domain structure by poling could be explained to calculate the change in the area with the individula axis. Therefore, the total amount of the domains oriented to c axis was estimated by the relation between I_<002>, kp, normalized polarization and E.From our domain configuration model, it was confirmed that there were two peaks of 90ﾟ domain rotation and one peak of 180ﾟ domain rotation. After the 90ﾟ domain switching, the domains in c direction were changed mainly by 180ﾟ rotation. As a result, the 90ﾟ domain switching decreased and 180ﾟ domain switching increased. We believe our study on domain structures of bulk ceramics may be useful for understanding the degradation characteristics in PZT thin films.