Forming-free resistive switching in ferroelectric Bi0.97Y0.03Fe0.95Sc0.05O3 film for RRAM application

Electromechanical and resistive switching properties were investigated in ferroelectric rhombohedral Bi0.97Y0.03Fe0.95Sc0.05O3 (BYFSO) film, grown on fluorine-doped tin oxide coated glass substrate. Piezoforce microscopy images of the BYFSO film after the electrical writing indicates the ferroelectric domains were switched completely towards the upward and downward direction at 8 V DC bias voltage, which is analogous to the ferroelectric hysteresis curve. The resistive switching effect was investigated on the Ag/BYFSO/FTO RRAM device configuration through conventional I - V characteristics. The charge transport process in Ag/BYFSO/FTO resistive device is transformed from Ohmic to space charge limited current conduction mechanism. The endurance characteristics ensure a stable bipolar resistive switching effect with a large memory window of OFF/ON ratio about similar to 100 for 50 repeatable testing cycles. From the impedance spectroscopy analysis, it is observed that the bulk resistance plays a significant role during the SET-RESET process, by large degradation of resistance from megaohm (high resistance state) to kiloohm (low resistance state). The oxygen vacancy induced conductive filaments are responsible for achieving the various resistive states in the device.