Improvement of ferroelectric property by Lanthanum (La)-doping of BiFeO3 (BFO) and strain effect of high quality superlattice films deposited at temperature. >= 700 degrees C was shown in this study. The in-pane (200) radial scans showed that films at deposition temperature above 700 degrees C behaved high strained similar to-1.4% and showed epitaxity properties. The La-doped BFO superlattice structure also behaved higher polarization value similar to 197 mu C/cm(2) and lower leakage current density comparing with BFO superlattice structure shown in our previous study. The ferroelectric properties of superlattice structures are enhanced by lattice strain and strongly correlated with the defect state of films. (C) 2012 Elsevier B.V. All rights reserved.