Characteristics of the SrBi2Nb2O9 Thin Films Deposited by RF Magnetron Sputtering with Controlling of Bi Contents

Abstract

The <TEX>$SrBi_2$</TEX><TEX>$Nb_2$</TEX><TEX>$O_{9}$</TEX> (SBN) thin films were deposited with <TEX>$SrNb_2$</TEX><TEX>$O_{6}$</TEX> / (SNO) and <TEX>$Bi_2$</TEX><TEX>$O_3$</TEX> targets by co-sputtering method. For the growth of SBN thin films, we adopted the various power ratios of two targets; the power ratios of the SNO target to <TEX>$Bi_2$</TEX><TEX>$O_3$</TEX> target were 100 W : 20 W, 100 W : 25 W, and 100 W : 30 W during sputtering the SBN films. We found that the electrical properties of SBN films were greatly dependent on Bi content in films. The <TEX>$Bi_2$</TEX>Pt and <TEX>$Bi_2$</TEX><TEX>$O_3$</TEX> phase as second phases occurred at the films with excess Bi content greater than 2.4, resulting in poor ferroelectric properties. The best growth condition of the SBN films was obtained at the power ratio of 100 W : 25 W for the two targets. At this condition, the crystallinity and electrical properties of the films were improved at even low annealing temperature as <TEX>$700^{\circ}C$</TEX> for 1h in oxygen ambient and the Sr, Bi and Nb component in the SBN films were about 0.9, 2.4, and 1.8 respectively. From the P-E and I-V curves for the specimen, the remnant polarization value (<TEX>$2P_{r}$</TEX>) of the SBN films was obtained about 6 <TEX>$\mu$</TEX>C/c <TEX>$m^2$</TEX> at 250 kV/cm and the leakage current density of this thin film was <TEX>$2.45<TEX>$\times$</TEX>10^{-7}$</TEX> <TEX>$A/cm^2$</TEX> at an applied voltage of 3 V.V.