Impact of crystallinity on coexistence of negative differential resistance (NDR) and write once read many (WORM) resistive switching memory in multiferroic BiFeO<inf>3</inf> (BFO)

The materials exhibiting the negative differential resistance (NDR) and write once read many (WORM), simultaneously are potential candidates for electronic devices such as oscillators and permanent storage devices. Here in, we investigated the impact of crystallinity on coexistence of NDR and WORM resistive switching on Cu(top contact)/BiFeO3 (amorphous/crystalline) (BFO as active material)/FTO (bottom electrode) memory device. The multiferroic BiFeO3 (BFO) active material is synthesized using a low-cost solution process on FTO substrates and thermal evaporation was used for deposing metal copper as the top contacts. The present device Cu/am-BFO/FTO showed the coexistence of WORM with high Ion/Ioff ratio of ~ 103 and NDR with peak (Vp) and valley (Vv) voltages ~ − 0.26 V and − 1.23 V, respectively. The power consumption is significantly low, ~ 66.94 µW in NDR region for am-BFO. The device with active crystalline material, i.e., Cu/c-BFO/FTO exhibits peak (Vp) and valley (Vv) voltages ~ − 1.22 V and − 1.40 V, respectively, and the power consumption is ~ 1.08 mW for devices based on crystalline BFO as an active material. The retention and endurance values are ~ 103 s and 103 cycles. The repeatability of the bipolar resistive switching of c-BFO is measured for 100 cycles, and relative cumulative Weibull distribution plots show the filament’s stability for both set and reset states. Thus, these results demonstrate the interplay between different switching characteristics in BFO, which can be tailored by manipulating the crystallinity of the active material.