Ferroelectric BiFeO3 thin films with Nd-Cr (or Sm-Cr) co-substitution (denoted by BNdFCr and BSmFCr, respectively) were deposited on the Pt(2 0 0)/TiO2/SiO2/Si(1 0 0) substrates by a chemical solution deposition method. X-ray diffraction patterns revealed the formation of BNdFCr and BSmFCr thin films without any secondary phases. The co-substituted BNdFCr (or BSmFCr) thin films, which were annealed at 550 degrees C for 30 min in N-2 atmosphere, exhibited enhanced electrical properties compared to BFO thin films with the remanent polarization (2P(r)) and coercive electric field (2E(c)) of 196, 188 mu C/cm(2) and 600, 570 kV/cm with the electric field of 800 kV/cm, respectively. The leakage current densities of BNdFCr and BSmFCr thin films measured at room temperature were approximately three orders of magnitude lower than that of BFO thin film, and the leakage current at room temperature of the thin films exhibited three distinctive conduction behaviors. Furthermore, the values of pulse polarizations [i.e., +(P*-P-boolean AND) or -(P*-P-boolean AND)] of BNdFCr and BSrnFCr thin films were reasonably unchanged up to 1.4 x 10(10) switching cycles. (c) 2007 Elsevier B.V. All rights reserved.