Metal-ferroelectric-insulator-semiconductor (MFIS) capacitors with (BiFeO3) (BFO) ferroelectric layer and hafnium oxide (HfO2) insulator layer were fabricated. The surface morphology was examined by the atomic force microscopy (AFM) with different incident angles. The size of memory window as a function of argon to oxygen ratio (Ar/O-2) was studied. The maximum memory window is 2.4 V obtained from a sweep voltage of 8 V when the Ar to O-2 gas ratio is 5. The leakage current which is dependent on the peak intensity of BFO phases was characterized. The charge injection effect determined from the surface roughness was suggested. The oxide trapped charges were measured to explain the charge injection effect. (C) 2009 American Vacuum Society. [DOI: 10.1116/1.3021025]