Fabrication and ferroelectric studies of (Bi, Gd)4Ti3O12 thin films grown on Pt/Ti/SiO2/Si and p-type Si substrates

Lead-free bismuth-layered perovskite ferroelectric Bi3.4Gd0.6Ti3O12 (BGT) thin films have been successfully deposited on Pt(1 1 1)/Ti/SiO2/Si and p-type Si(1 0 0) substrates by a sol-gel spin-coating process followed by annealing. The formation of BGT thin film was found to be sensitive to the annealing temperatures. The remanent polarization (2Pr) and coercive field (2Ec) of the metal-ferroelectrics-metal capacitor using a BGT film deposited on Pt(1 1 1)/Ti/SiO2/Si by annealing at 700 °C were 49.6 μC/cm2 and 249 kV/cm, respectively, with 260 kV/cm of applied field. The BGT film exhibits a good fatigue resistance up to 1.45×1010 switching cycles at a frequency of 1 MHz.The metal-ferroelectrics-semiconductor type capacitor using a BGT film grown on a bare p-type Si(1 0 0) substrate exhibits a good capacitance-voltage (C-V) characteristics. By changing AC frequencies from 1 kHz to 10 MHz, the C-V characteristics, including total capacitance and memory window (∼1 V), were not affected. The temperature dependency of C-V and I-V characteristics for the MFS type capacitor were interpreted in terms of a new anomalous thin layer between the BGT thin film and the p-type Si(1 0 0) substrate.