Oxygen‐Vacancy‐Mediated Amorphous Ga 2 O 3 for Neuromorphic Multicolor Image Sensor

Abstract Inspired by the remarkably high efficiency of the human retina, neuromorphic image sensors are attracting more and more attention. As the core component for optoelectronic conversion, optoelectronic synapses are hotly pursued under the stimulus of monochromatic light, limiting the capability of full‐color imaging in one active cell. Herein, by leveraging the outstanding broadband photoresponse and distinct wavelength‐dependent temporal current evolution, a neuromorphic multicolor image sensor is demonstrated based on oxygen‐vacancy‐mediated amorphous Ga 2 O 3 (a‐Ga 2 O 3 ) thin film. Typical synaptic functions, including paired‐pulse facilitation and the learning‐relearning process, have been successfully mimicked under different light illumination. A 10×10 imaging array well identifies multicolor patterns under raster scanning of focused laser beams of 638, 520, and 405 nm, which is enabled by the combination of distinguishable photocurrent levels and memorizing/fading time of the final pictures among different wavelengths. The underlying mechanism of the visible photoresponse is further explored through scanning photocurrent microscopy measurement, suggesting the synergetic role of optical and electric fields on the dynamic behaviors of the photo‐induced carriers assisted by the V O ‐related sub‐bandgap defects. This work provides a strategy to encode the color information in the time domain, offering a potential solution to construct a compact filter‐free machine vision system in the future.