Buffer layer dependence of B3.15Nd0.85Ti3O12 (BNdT) based MFIS capacitor for FeFET application

Ferroelectric B_3.15Nd_0.85Ti₃O₁₂ (BNdT) thin films were deposited on SrTiO₃/Si, HfO₂/Si and Si substrates respectively by sol-gel process. The electrical properties were studied for Metal-Ferroelectric-Semiconductor (MFS) and Metal-Ferroelectric-Insulator-Semiconductor (MFIS) capacitors. The MFIS structure exhibited well clockwise capacitance-voltage hysteresis loops due to the ferroelectric polarization of BNdT thin film achieved. The maximum memory windows were 3.2 V and 4.7 V, respectively for BNdT deposited on SrTiO₃ and on HfO₂ buffer layers. In comparison, the memory window of the thin film on Si substrate was 2.8 V. The leakage current of the structure with a buffer layer was much lower than that without a buffer layer. The leakage current of the thin film deposited on SrTiO₃/Si was of the order of 10^-9-10^-8 A/cm². The electrical properties of the MFIS structures were improved. The results show that the BNdT based MFIS capacitor is a promising candidate for ferroelectric field effect transistor (FeFET).