Study on polarization characteristics of BiFeO₃ thin films prepared by sol-gel spin-coating technology

¹ School of Microelectronics and Solid-State Electronics, University of Electronic Science and Technology of China, Chengdu, 610054 Sichuan, P.R. China
² Institute of Microelectronics, Tsinghua National Laboratory for Information Science and Technology, Tsinghua University, 100084 Beijing, P.R. China
³ Department of Electrical Engineering and Computer Science, University of Central Florida, Orlando, 32816 Florida, USA

^a e-mail: ze.jia@ieee.org

Received: 26 March 2015
Revised: 26 May 2015
Accepted: 18 June 2015
Published online: 23 July 2015

Abstract

The ferroelectric polarization properties of bismuth ferrite (BFO) thin films deposited on Pt(111)/TiO₂/SiO₂/Si(100) substrates by sol-gel spin-coating technology affected by the processes and dopants have been studied and analyzed tentatively. The results indicate BFO thin film should be introduced to a rapid thermal annealing (RTA) process at N₂ atmosphere. The enhanced ferroelectric polarization properties were observed in Mn and La doped BFO thin films, because ion substitution may improve the inherent volatility of Bi atoms, valence fluctuation of Fe ions and magnetic spin structures, reducing the formation of oxygen vacancies. The increased remnant polarization observed in the BFO thin film with a lead zirconate titanate (PZT) seeding layer has also been analyzed as the probable results of small changes of lattice parameters caused by constraint stress, reduced defects and decreased leakage current density, which are contributed by the PZT seeding layer possibly. Moreover, the remnant polarization approximately 79 μC/cm² is observed in (Bi_0.95La_0.05)FeO₃ (BLFO) thin film with a PZT seeding layer, which is twice and treble the values of BFO thin films with and without a PZT seeding layer, indicating PZT seeding layer is much more effective for BLFO thin film which has a substitution at A site.