STRUCTURAL DEFECTS IN SR0.7BI2.3TA2O9 THIN-FILM FOR FERROELECTRIC MEMORY

Using transmission electron microscopy (TEM), we studied structural de fects in a Sr0.7Bi2.3Ta2O9 (SBT) thin film to be used for ferroelectri c memory devices. We examined the effects of the substrate, crystal co ntinuity, and dislocations in crystals as major causes of defects. For this study, we used an SBT thin film grown From an alkoxide solution. Since crystal growth was hardly influenced by the substrate, the subs trate had little influence on the occurrence of defects resulted in mi sfit of lattice constant. Regions of partially low crystal continuity were observed in the SBT thin film. In these regions, the orientation was still uniform, but the continuity of the crystal grain was low bec ause of the defects. In addition, variation in contrast was observed i n the crystals, however, no obvious variation in chemical composition was found in this region of varying contrast. Therefore, the contrast variation is considered to be attributed to the dislocation. Such a di slocation was found to be occurred in the direction of the (20 (1) und er bar (0) under bar) plane in many instances. The defects in the SBT film were also confirmed by the TEM observation.