SPICE model for the current-voltage characteristic of resistive switching devices including the snapback effect

Under certain conditions, the current-voltage (I-V) characteristic of transition metal oxide (TMO)-based resistive switching (RS) devices exhibits the so-called snapback effect. This effect is not always observable and is a feature associated with the abrupt reduction of the voltage drop across the device caused by the formation of a filamentary pathway spanning the insulating layer. Since the device electrical behavior must always comply with the load line constraint, the current increases following a trajectory dictated by the circuit series resistance. When the voltage drop across the device reaches the minimum value required to induce the ion movement, the filament starts to expand laterally with the consequent current increase. Remarkably, this phase develops at a fixed voltage drop between the device terminals. In this work, a simplified SPICE model for the intrinsic I-V curve of RS devices based on the memdiode concept (diode + memory) which includes the snapback effect is proposed. A thorough analysis of the role played by the model parameters related to that aspect is presented. Simulations are compared with experimental data obtained from Ta2O5-based RS devices.