Effect of excess Bi 2O 3 on the ferroelectric and dielectric properties of Bi 3.25La 0.75Ti 3O 12 thin films by RF sputtering method

Abstract

Bi 3.25La 0.75Ti 3O 12 (BLT) thin films derived from different amounts of Bi 2O 3 excess content were fabricated on Pt/TiO 2/SiO 2/Si using RF-magnetron sputtering method. The effect of Bi 2O 3 excess content on the microstructure, ferroelectric and dielectric properties of the BLT films was investigated. The X-ray diffraction analysis reveals a layered perovskite structure phase without pyrochlore phase for all the BLT films. Appropriate amount of excess bismuth improves remnant polarization of the BLT film, while too much excess bismuth leads to a reduction in remnant polarization and an increase in coercive voltage. P– V loops of well-established squareness were observed for the BLT films derived from a moderate amount of Bi 2O 3 excess (7.5 mol%), where a remnant polarization (2Pr) of 25.26 μC/cm 2 and coercive voltage (Vc) of 3.62 V were shown. A similar change in dielectric constant with the increasing of Bi 2O 3 excess content was also observed. Moreover, the BLT thin film derived from 7.5 mol% Bi 2O 3 excess shows the best fatigue resistance characteristics and about 8.1% polarization degradation after 1 × 10 9 read/write switching cycles.