Study on the variations of microstructures and domain structures of Bi _3.35La_0.85Ti₃O₁₂ ferroelectric thin films formed by two-step rapid thermal annealing (RTA) process utilizing piezoresponse force microscope (PFM)

Recently, La-substituted Bi₄Ti₃O₁₂ (BLT) has been widely studied as a candidate material for FeRAM due to its superior properties like high fatigue endurance with relatively lower crystallization temperature. In this study, we attempted to examine ferroelectric properties of various BLT thin films that were made using two-step rapid thermal annealing (RTA) process. The microstructure of BLT thin film is appeared as a critical factor to maximize ferroelectric properties. We found that the 2nd annealing temperature in two-step RTA process played an important role in determining the crystalline orientation of BLT thin films. Grain orientations of the BLT thin films were interpreted based on x-ray diffraction (XRD) in conjunction with piezoresponse images that were obtained utilizing piezoresponse force microscope (PFM). In addition, the results were correlated with the hysteresis loops.