Electrical properties of sol-gel derived BLT films on Si(100) substrates using LaAlO₃ buffer layers

LaAlO₃ and Bi_3.35La_0.75Ti₃O₁₂ (BLT) were chosen as the respective buffer layer and ferroelectric film in forming MFIS (metal-ferroelectric-insulator-semiconductor) diodes on Si(100) substrates. LaAlO₃ films were prepared by an MBD (molecular beam deposition) method, and they were subjected to ex situ N₂ annealing in a rapid thermal annealing (RTA) furnace at 800 °C for 1 min. On the optimized LaAlO₃/Si structure, Bi_3.35La_0.75Ti₃O₁₂ films with 150-nm-thickness were deposited by a sol-gel technique and they were crystallized in O₂ atmosphere at temperatures ranging from 650 °C to 750 °C. The memory window width in C-V (capacitance-voltage) curve of the 750 °C-crystallized BLT/LaAlO₃/Si diode was about 2.7 V for a voltage sweep of 10 V. It was also found that the retention time of this diode was longer than 3 hours.