Effects of Bi2O3, TiO2, and Bi4Ti3O12 Seeding Layers on the Structural and Electrical Properties of Bi3.25La0.75Ti3O12 Thin Films Grown by a Sol–Gel Method

Abstract

Ferroelectric Bi3.25La0.75Ti3O12 (BLT) thin films with Bi2O3, TiO2, and Bi4 Ti3O12 (BTO) seeding layers were prepared on Pt/TiO2/SiO2/Si (100) substrate by a sol–gel technique. The effects of the different seeding layers on the structural and electrical properties of the BLT films were investigated. X-ray diffraction indicated that the predominant orientation of the BLT thin film on the BTO seeding layer was (117). Growth of films with the Pt/BLT/Bi2O3/Pt structure was oriented differently from that of films with the Pt/BLT/TiO2/Pt and Pt/BLT/Pt structures. In addition, in comparison with the BLT film deposited directly on Pt, the TiO2 layer substantially enhanced the leakage current resistance of the BLT film. The ferroelectric nature of the BLT thin film was substantially improved by use of a BTO seeding layer. In an applied field of 750 kV/cm, the remnant polarization (2P r) of the Pt/BLT/BTO/Pt capacitor was 61.5 μC/cm2. After 1010 switching cycles, 2P r of the BLT, BLT/Bi2O3, BLT/TiO2, and BLT/BTO films was degraded by approximately 13, 11, 1, and 2%, respectively, indicating that all the capacitors with the different seeding layers had good polarization fatigue characteristics.