A model based comparison of BiFeO3 device applicability in neuromorphic hardware

Two terminal devices with switchable resistance have been of interest to electrical engineers for a long time, but only in the last few years has this attracted widespread attention. Recently a BiFeOe (BFO) capacitor-like metal-insulator-metal (MIM) structure was proposed as a synthetic synapse in neuromorphic systems, implementing voltage waveform driven spike timing dependent plasticity (STDP). Using a new device model that faithfully reproduces measurements of BFO-MIM structures we analyze how the switching characteristic affects the STDP learning window. Our simulations indicate that the gradual increase in the resistance change of BFO MIM structures result in a robust STDP with a biologically realistic learning window, whereas a distinct threshold followed by a steep hysteresis curve produce a narrow learning window and inflict strict operating conditions. Therefore we conclude that the steepness of the current voltage hysteresis curve is a fundamental characteristic to consider when designing synthetic synapses for neuromorphic hardware.