Fabrication of MFIS diodes using BLT (Bi,La)4Ti3O12 and LaAlO3 buffer layers

We fabricated MFIS (metal-ferroelectric-insulator-semiconductor) diodes with Bi_3.35La_0.75Ti₃O₁₂ (BLT) films and lanthanum aluminate (LaAlO₃) buffer layers formed on Si(100) substrates. LaAlO₃ films were prepared by an MBE (molecular beam epitaxy) method. After the film deposition, they were subjected to ex site N₂ annealing in a rapid thermal annealing (RTA) furnace at 800°C for 1 min. BLT films (150 nm) were deposited on these LaAlO₃/Si structures using a sol-gel technique. The memory window of this BLT film annealed in O₂ ambient at 750°C for 10 min was about 2.7 V. It was found that the leakage current density was on the order of 10^-6 A/cm² at an electric field of 500 kV/cm. It was also found from the retention measurement that the capacitance values biased at a voltage in the hysteresis loop did not change for more than 3 hours.