Electrical and ferroelectric properties of rare-earth-doped Na0.5Bi4.0RE0.5Ti4O15 (RE = Eu, Gd and Dy) thin films

Abstract

A study of the structural, electrical and ferroelectric properties of layered Aurivillius-type Na0.5Bi4.5Ti4O15 (NaBTi) and Na0.5Bi4.0RE0.5Ti4O15 (RE = Eu, Gd and Dy) thin films is reported. These films were fabricated on Pt-coated Si(100) substrates by using a chemical solution deposition method followed by a heat treatment. The rare-earth elements used as dopants, such as Eu, Gd and Dy, were found to be effective in improving the leakage current densities and the ferroelectric properties of the layered Na0.5Bi4.5Ti4O15 thin films without affecting their original Aurivillius structures. Based on the measured ferroelectric polarization-electric field (P−E) hysteresis loops, we found that the Gd-doped NaBTi thin film, among all the films, exhibited the highest ferroelectric remnant polarization of 2Pr = 37.4 μC/cm2 and a low coercive electric field of 2Ec = 187 kV/cm at an applied electric field of 475 kV/cm. Furthermore, the lowest value of the leakage current density of 6.12×107 A/cm2 at an applied electric field of 100 kV/cm was measured for the Gd-doped NaBTi thin film.