Ferroelectric field effect transistor (FFET) is a promising candidate for non-volatile randomaccess memory because of its high speed, single device structure, low power consumption, andnondestructive read-out operation. Currently, however, such ideal devices are commercially notavailable due to poor interface properties between ferroelectric film and Si substrate, such asleakage current and interdiffusion etc. So we choose YSZ and HfO2 insulating thin films asbuffer layer due to they possess relatively high dielectric constant, high thermal stability, lowleakage current, and good interface property with Si substrates. Two structural diodes ofPt/BNT/YSZ/Si and Pt/SBT/HfO2/Si were fabricated, and the microstructures, interfaceproperties, C-V, I-V, and retention properties were investigated in detail. Experimental resultsshow that the fabricated diodes exhibit excellent long-term retention properties, which is due tothe good interface and the low leakage density, demonstrating that the YSZ and HfO2 bufferlayers are playing a critical modulation role between the ferroelectric thin film and Si substrate.