A Recoverable Synapse Device Using a Three-Dimensional Silicon Transistor

To prepare for the upcoming big-data era, numerous attempts are underway to develop a neuromorphic system which is capable of imitating a biologic neural network. Despite the significant improvements to software-based artificial neural networks (ANNs) recently, they remain inefficient in terms of energy use. Alternatively, many researchers have been attracted to hardware-based ANNs by fundamentally mimicking neural circuits and synapses. In this study, a two-terminal silicon-channel synapse (SINAPSE) with a poly-Si/SiO₂/Si₃N₄ gate stack over a silicon channel is introduced, and demonstrated the smallest size of a synapse device reported thus far, along with reliable, low-power performance. A distinctive feature of SINAPSE is that it emulates synaptic recovery, a retrieval process for neurotransmitters which would be otherwise depleted. By applying an electrical recovery pulse to SINAPSE, synaptic recovery was for the first time successfully imitated. Experimental results demonstrate the potential of the curable SINAPSE as a fundamental unit in neuromorphic circuitry.