Optically Modulated Threshold Switching in Core–Shell Quantum Dot Based Memristive Device

Abstract

The threshold switching (TS) phenomenon in memristors has drawn great attention for its versatile applications in selectors, artificial neurons, true random number generators, and electronic integrations. The transition between nonvolatile resistive switching and volatile TS modes can be realized by doping, varying annealing and voltage sweeping conditions, or imposing different compliance current. Here, a strategy is reported to achieve such transition by the noninvasive UV light stimulus based on InP/ZnS quantum dot (QD) memristor. The core-shell InP/ZnS QDs with quasi-type II band alignment ensures photoexcited electrons localized in InP core, photoexcited hole state distributed in the outer shell, and subsequent lifetime controlling of conductive filament under light irradiation. Systematic mechanism investigations indicate that UV photogenerated holes are accumulated on the surface of the QD film, which is consistent with rapid transfer of photogenerated holes in the coreshell InP/ZnS structure. Based on the light-modulated effect, a reconfigurable 9 × 9 visual data storage array with a key pattern and a simple leaky integrateand-fire circuit are constructed. These results suggest the potential of direct optical modulation of memory mode through energy band engineering, leading to future optoelectronic and electronic device for the implementation of neuromorphic visual system and artificial neural networks.

Emerging Materials for Neuromorphic Devices and Systems

“… (I) Integration-and-fire behavior emulated by InP/ZnS-based memristor. Reproduced with permission ( Wang et al., 2020 ). Copyright 2020, John Wiley & Sons, Inc. …”

“…In addition, memristors have also been used to realize the integrate-and-fire model of neuron by optical modulation. An artificial neuron was fabricated using core-shell quantum dots (QDs) composed of InP core and ZnS shell ( Wang et al., 2020 ). A device that had Ag/(InP/ZnS) QDs/ITO structure showed non-volatile resistive switching behavior under a dark condition, but showed threshold switching behavior under UV illumination ( Figure 10 G).…”

Advanced atomic force microscopy-based techniques for nanoscale characterization of switching devices for emerging neuromorphic applications

“…The following describes a recent study on changes in switching types by analyzing peripheral charges of CFs inside films. Wang et al ( 2020 ) reported an analysis using KPFM on instant changes between threshold switching and resistive switching during UV irradiation of films with InP/ZnS quantum dot-based memristive devices. There is a quantum dot-based switching layer between Ag and ITO electrodes (Fig.…”

Recent Advances of Volatile Memristors: Devices, Mechanisms, and Applications

“…InP/ZnS quantum dots (QDs)-based memristor; the memristive mode of the device can be transited from nonvolatile resistive switching to volatile TS under UV illumination. [61] In this work, the designed visual neuron based on LIF model was implemented on InP/ZnS QD-based memristor (Figure 6b). During the experiment, the memristor showed TS behavior UV illumination.…”