Bi4-xLaxTi3.0O12 (BLT, x=0.67-0.70) ferroelectric thin films were prepared on a single crystalline aluminum oxide film onto Si substrate (c-Al2O3/Si), and amorphous phase aluminum oxide film onto Si substrates (a-Al2O3/Si) by the sol-gel method. In order for crystallization, the as-coated films were annealed at the temperature of 650 and 700 degreesC for 30 min. The crystalline quality, surface morphologies and electrical properties were affected by the substrate types as well as the annealing temperature. The BLT films annealed at above 650 degreesC exhibited typical bismuth layered perovskite structures with (001) preferred orientation. From X-ray diffraction analyses, the BLT films coated on c-Al2O3/Si substrate were higher in reflection peaks and smaller in full width at half maximum (FWHM) values compared with the ones coated on a-Al2O3/Si substrate. The R-rms value of the film annealed at 700 degreesC on c-Al2O3/Si substrates was three times smaller than that of the film coated on a-Al2O3/Si substrate, showing a rather smooth surface when it was coated on c-Al2O3/Si substrate. The memory window voltage of the BLT film coated on c-Al2O3/Si substrate was 2.5 V, which is about twice compared with the one coated on a-Al2O3/Si substrate. The leakage current of BLT film annealed at 650 degreesC was approximately 1 x 10(-7) A/cm(2) at the applied voltage of 3 V for both samples. (C) 2003 Elsevier B.V. All rights reserved.