Metal-ferroelectric-insulator-semiconductor (MFIS) capacitors and field effect transistors (FETs) with Al/BiFeO3/Y2O3/Si structure were fabricated. The capacitance-voltage (C-V) characteristics exhibit clockwise hysteresis loop due to the ferroelectric polarization of BiFeO3. The maximum C-V memory window was 0.88 V at a sweep voltage range of 5 V. Low leakage current density of 7 X 10(-9) A/cm(2) was measured at an applied voltage of 5 V using MFIS capacitors. The I-DS-V-DS and I-DS-V-GS characteristics of MFISFETs were measured. The subthreshold slope was 170 mV/dec and the maximum electron mobility was 155 cm(2)/V s. (C) 2009 American Vacuum Society. [DOI: 10.1116/1.3058727]