Preparation and properties of Bi₂SiO₅/Si structures

Bismuth silicate (Bi₂SiO₅) films, expected as the intermediate buffer layer between the bismuth layer-structured ferroelectrics (BLSF) and silicon substrate were prepared on (100)-oriented silicon wafers by rf magnetron sputtering. The c-axis-oriented Bi₂SiO₅ films with smooth surface morphology were obtained at the substrate temperature of 400°C. The leakage current density is on the order of 10^-10 A·cm^-2, under the applied electric field of less than 350 kV·cm^-1. From capacitance-voltage characteristics measurement results, it is worth noting that hysteresis is hardly observed. The interface trap density at the midgap is estimated to be approximately 6 × 10¹² cm^-2·eV^-1. The numerical evaluation results indicate that the metal-ferroelectric-insulator-semiconductor (MFIS) capacitor can be reversed at a low applied voltage. This suggests that Bi₄Ti₃O₁₂/Bi₂SiO₅/Si structures are suitable for application for ferroelectric memory devices.