Formation of Silicate-Added (Bi,La)₄Ti₃O₁₂ Films on LaAlO₃/Si(100) Structures

Abstract

We fabricated MFIS (metal-ferroelectric-insulator-semiconductor) diodes with ((Bi,La)₄Ti₃O₁₂: BLT) films and lanthanum silicate (La₂SiO₅: LSO)-added BLT films formed on LaAlO₃/Si(100) structures. LaAlO₃ films were prepared by an MBD (molecular beam deposition) 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 and LSO-added BLT films were deposited on these LaAlO₃/Si structures using a sol-gel technique. The memory windows of BLT and LSO-added BLT films were 3.0 V and 2.1 V, respectively. It was found from the current density-voltage (I-V) characteristics that the insulation property of the LSO-added BLT film was superior to that of the BLT film. We conclude from these results that LaAlO₃ is an excellent candidate of a buffer layer for forming ferroelectric-gate FETs and that the LSO-added BLT film is suitable for low voltage operation of the FETs.

Keywords:

• BLT
• lanthanum silicate
• LaAlO₃
• memory window
• MFIS structure
• FeRAM