Large Remanent Polarization in Sm-Substituted BiFeO3 Thin Film Formed by Chemical Solution Deposition

Bi1-xSmxFeO3 (x = 0-0.15) (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 degrees C in air and in N-2. It was found that Sm-substitution for Bi in BiFeO3 increased the grain size and the leakage current density. The optimal concentration for improving remanent polarization (P-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-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 mu C/cm(2) and 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. (C) 2010 The Japan Society of Applied Physics