Equalizing Excitation-Inhibition via the Ambipolar Photoresponse of Al2O3/graphene Hybrid Neuromorphic Devices

Intrigued by the artificial intelligence and brain-like neural networks, the photoelectronic neuromorphic devices that can simulate synaptic functions have been attracting wide attention. However, equalizing excitation-inhibition has been seldom artificially realized despite its fundamental feature in a biological system. In this work, an artificial synapse is proposed based on a sandwiched Ag/Al 2 O 3 /graphene/ITO photodetector. The device exhibits a special ambipolar photoresponse at the millivoltage as a result of the interfacial trapping effects. Under the coupled light and electrical stimulus, the synaptic excitatory, inhibitory signals and their recovery are emulated on a single device via the positive and negative photoresponse, respectively. Further, the biologically dynamic balance of excitation and inhibition is reproduced on a simple analogous system integrating multiple photoelectronic synaptic cells. These remarkable results provide a potential foundation for building hardware units with neuromorphic architecture to mimic the complex human brain functionalities.