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This letter deals with short-term plasticity (STP) effects in the conduction characteristics of single crystalline ZnO nanowires, including potentiation, depression and relaxation phenomena. The electrical behavior of the structures is modeled following Chua's approach for memristive systems, i.e. one equation for the electron transport and one equation for the memory state of the device. Linear conduction is assumed in the first case together with a voltage-controlled rate balance equation for the normalized conductance. The devices are subject to electrical stimuli such as ramped and pulsed voltages of both polarities with varying amplitude and frequency. In each case, the proposed model is able to account for the STP effects exhibited by ZnO highlighting its neuromorphic capabilities for bio-inspired circuits. An equivalent circuit representation and the SPICE implementation of the compact model is also provided.

This letter deals with the compact modeling of the I-V characteristics of single crystalline ZnO nanowires (NW) attached to two metal electrodes (Pt and Ag). Starting from the standard model of electron transport in these structures based on the series combination of two back-to-back Schottky diodes, three different approaches which account for the role played by the NW series resistance are presented. The first approach considers a fixed potential drop across the NW, the second one involves the solution to the problem of a diode with linear and nonlinear series resistances using the Lambert W function, and the third one consists in a behavioral model with continuous first derivative suitable for circuit simulation environments. In the three cases, the proposed solutions are consistent with the observed electrical constraints both at low (linear I-V relationship) and high (current saturation) voltages.