Ferroelectric (Bi_4-x,La_x)Ti₃O₁₂ (BLT) thin films for metal-ferroelectric-insulator-semiconductor (MFIS) structures

We propose ferroelectric (Bi_3.25,La_0.75)Ti₃O₁₂ (BLT) thin films for metal-ferroelectric-insulator-semiconductor (MFIS) structures. The BLT thin films were prepared on SiO₂/Si (100) and yttria-stabilized zirconia (YSZ) buffered SiO₂/Si (100) substrates using pulsed laser deposition (PLD). The BLT thin films tended to grow with a c-axis preferred orientation with increasing substrate temperature above 540 °C. Transmission electron microscopy (TEM) and Auger electron spectroscopy (AES) revealed that there was no inter-diffusion at the interface of the BLT thin films grown at temperatures as low as 620 °C. The MFIS structure exhibited a capacitance-voltage (C-V) hysteresis (memory window) due to ferroelectric polarization. The asymmetric behaviors of the C-V and the leakage current (I-V) characteristics are discussed in terms of both electron injection from Si and the ferroelectric polarization effect.