Large Remanent Polarization in Sm-Substituted BiFeO3Thin Film Formed by Chemical Solution Deposition

Bi1-xSmxFeO3($x=0{\mbox{--}}0.15$) (BSFO) thin films were formed on Pt/Ti/SiO2/Si(100) substrates by chemical solution deposition. The spin-coated, dried, and prefired thin films were finally crystallized at 500 \mbox{\circC} in air and in N2. It was found that Sm-substitution for Bi in BiFeO3increased the grain size and the leakage current density. The optimal concentration for improving remanent polarization ($P_{\text{r}}$) was characterized to be 5 at. %. In 10 and 15 at. % BSFO films, incorporation of Sm atoms was found to be excess, leading to degradation of ferroelectric properties. The $P_{\text{r}}$ and coercive electric field values in 5 at. % BSFO film measured at electric field of 1.5 MV/cm and frequency of 25 kHz were 82 \mbox{$\mu$}C/cm2and 0.35 MV/cm, respectively. In addition, the minimal coercive electric voltage of 7.5 V was achieved in a 126-nm-thick 7.5 at. % Sm-substituted BFO film.