A novel face-to-face annealing process was used to investigate the enhanced electrical characteristics in Bi3.25La0.75Ti3O12 (BLT)/Al2O3/Si capacitors annealed at high temperatures. The low leakage current of BLT/Al2O3/Si capacitors can be obtained after high temperature annealing and the mechanism has been clarified and attributed to the formation of Si-rich aluminum oxide. The surface composition of aluminum oxide after annealing was further analyzed by X-ray photoelectron spectrometer (XPS) and XPS spectra revealed that the aluminum oxide would react with both Si substrate and BLT thin films to form Si-rich aluminum oxide. Because the aluminum oxide has weaker bonding than that of silicon oxide, Si composition can quench the electrical defects in aluminum oxide so as to reduce the leakage current of BLT/Al2O3/Si capacitors. (C) 2003 The Electrochemical Society.