Ferroelectric properties of Sr2Bi4Ti5O18 thin films

Abstract

Bi-based layered ferroelectric thin films of Sr2Bi4Ti5O18 (SBTi) were prepared by pulsed-laser deposition. The c-axis-oriented SBTi films were grown on SrRuO3 seeded Pt/TiO2/SiO2/Si substrates while polycrystalline SBTi films were grown on Pt/TiO2/SiO2/Si substrates. The measurements of ferroelectricity revealed that the direction of spontaneous polarization was not along the c axis since the polarization of c-axis-oriented films was much less than that of randomly oriented films. There was no significant degradation of switchable charge at least up to 1011 cycles for the randomly oriented films, suggesting that, even with Ti which was widely accepted to contribute to the fatigue of Pb(Zr, Ti)O3, SBTi showed superior fatigue characteristics. The randomly oriented films also showed excellent retention characteristics after 105 s.