Laser-amplified nonvolatile charge trapping effect in semiconductor quantum dot structures*

Non-volatile regulation by optical means has long been a challenge due to the usual volatility of photoelectric effect of light excitation. This limitation hinders the evolution of optoelectronic technologies, particularly in optical memory. Traditionally, photodetectors record only transient optical signals, relying on ancillary electronic devices for data retention and manipulation. Such multi-device integration delivers poor efficiency and high-power consumption. Thus, achieving direct nonvolatile storage and processing of light information is highly desirable, spurring tremendous research. Here, we report the discovery of a light-induced nonvolatile trapping effect that allows for highly effective and lasting storage of optical signals, in a simple two-terminal molybdenum disulfide quantum dot memory structure. Moreover, the charge trapping capability can be enhanced almost threefold after laser irradiation, in contrast to pure electrical means. We feature a new barrier modulation model driven by the synergistic action of electric pulse and laser signal. More interestingly, by designing an optoelectronic memory array, we successfully demonstrate that this effect can be applied simultaneously for image sensing and preprocessing, as well as in neuromorphic reinforcement learning. Undoubtedly, this work suggests a novel approach for designing multifunctional photoelectronic devices in AI applications.