Enhancing Speed and Stability of Polarization Reversal in Predominantly a/b-Axes-Oriented Bi4Ti3O12 Thin Films Deposited on Pt/Ti/SiO2/Si

Bi4Ti3O12-based thin films of a/b-axes orientation grown on standard-type Pt/Ti/SiO2/Si substrates are desirable for designing reliable ferroelectric devices. Herein, a/b-axes-oriented and randomly oriented Bi4Ti3O12 thin films are deposited on Pt/Ti/SiO2/Si through a sol-gel process. As expected, the a/b-axes-oriented films show a higher remnant polarization than that of randomly oriented films. The characteristic time tau of domain reversal in 74% a/b-axes-oriented Bi4Ti3O12 films is 1.1 ms, notably shorter than that (tau > 2.5 ms) for randomly oriented films. The dynamic hysteresis scaling relations of the randomly oriented 56% and 74% a/b-axes-oriented Bi4Ti3O12 films take the forms of ⟨A⟩ proportional to f(-0.106)E(0)(1.667), ⟨A⟩ proportional to f(-0.035)E(0)(0.952), and ⟨A⟩ proportional to f(-0.026)E(0)(0.600), respectively. The difference indicates that domain reversal in Bi4Ti3O12 films of predominant a/b-axes orientation exhibits higher stability compared with randomly oriented Bi4Ti3O12 films under varying electric fields E(E-0, f). The enhancing speed and stability of polarization reversal in predominantly a/b-axes-oriented Bi4Ti3O12 films can be understood in terms of their layered-perovskite structure, large columnar grains, oxygen vacancies mobility, domain states, and polarization switching mechanism.