The BLT thin film and MgO buffer layer were fabricated using a metalorganic decomposition method and the DC sputtering technique. The MgO thin film was deposited as a buffer layer on SiO2/Si and Bi3.25La0.75Ti3O12 (BLT) thin films were used as a ferroelectric layer. The electrical of the metal ferroelectric insulator semiconductor (MFIS) structure were investigated by varying the Mao layer thickness. Transmission electron microscopy (TEM) shows no interdiffusion and reaction that suppressed by using the MgO film as a buffer layer. The width of the memory window in the C-V curves for the MFIS structure decreased with increasing thickness of the MgO layer. Leakage current density decreased by about three orders of magnitude after using MgO buffer layer. The results show that the BLT and MgO-based MFIS structure is suitable for non-volatile memory FETs with large memory window. (C) 2004 Elsevier B.V. All rights reserved.