Temperature-Modulated Short-Term and Long-Term Memory in Solution-Processed ZnO Schottky Synapses

This work reports a solution-processed Ag/ZnO nanorod-array/ZnO quantum-dot/indium tin oxide (ITO) Schottky photodiode engineered to mimic synaptic functions for neuromorphic optoelectronics. Barrier-height inhomogeneity (BHI) at the Ag/ZnO interface, along with oxygen adsorption–desorption processes, generates interfacial trap states that regulate charge trapping and release, enabling short-term memory (STM) and long-term memory (LTM) behaviors. Temperature-dependent I-V analysis reveals an increase in effective barrier height from 0.59 to 0.77 eV and a decrease in ideality factor from 3.328 to 2.80 in the temperature range from 303 to 423 K, confirming BHI-dominated transport. Optical pulse measurements demonstrate tunable synaptic plasticity, including enhanced STM at higher temperatures and LTM retention up to 647 s at room temperature. The results establish a temperature-modulated Schottky synapse capable of controllable neuromorphic photoresponses.