Ming Hsieh Department of Electrical Engineering, University of Southern California , 3737 W Way, Los Angeles, California 90089, United States.
Department of Electrical and Computer Engineering, University of Florida , Gainesville, Florida 32611, United States.
ACS Nano. 2017 Jul 25;11(7):7156-7163. doi: 10.1021/acsnano.7b03033. Epub 2017 Jun 28.
Excitatory and inhibitory postsynaptic potentials are the two fundamental categories of synaptic responses underlying the diverse functionalities of the mammalian nervous system. Recent advances in neuroscience have revealed the co-release of both glutamate and GABA neurotransmitters from a single axon terminal in neurons at the ventral tegmental area that can result in the reconfiguration of the postsynaptic potentials between excitatory and inhibitory effects. The ability to mimic such features of the biological synapses in semiconductor devices, which is lacking in the conventional field effect transistor-type and memristor-type artificial synaptic devices, can enhance the functionalities and versatility of neuromorphic electronic systems in performing tasks such as image recognition, learning, and cognition. Here, we demonstrate an artificial synaptic device concept, an ambipolar junction synaptic devices, which utilizes the tunable electronic properties of the heterojunction between two layered semiconductor materials black phosphorus and tin selenide to mimic the different states of the synaptic connection and, hence, realize the dynamic reconfigurability between excitatory and inhibitory postsynaptic effects. The resulting device relies only on the electrical biases at either the presynaptic or the postsynaptic terminal to facilitate such dynamic reconfigurability. It is distinctively different from the conventional heterosynaptic device in terms of both its operational characteristics and biological equivalence. Key properties of the synapses such as potentiation and depression and spike-timing-dependent plasticity are mimicked in the device for both the excitatory and inhibitory response modes. The device offers reconfiguration properties with the potential to enable useful functionalities in hardware-based artificial neural network.
兴奋性和抑制性突触后电位是哺乳动物神经系统多种功能的基础突触反应的两个基本类别。神经科学的最新进展揭示了腹侧被盖区神经元轴突末梢可以同时释放谷氨酸和 GABA 神经递质，从而导致兴奋性和抑制性突触后电位的重新配置。在半导体器件中模拟这种生物突触的特性的能力，在传统的场效应晶体管型和忆阻器型人工突触器件中是缺乏的，这可以增强神经形态电子系统在执行图像识别、学习和认知等任务的功能和多功能性。在这里，我们展示了一种人工突触器件的概念，即双极结型突触器件，它利用了两层半导体材料黑磷和硒化锡之间异质结的可调电子特性来模拟突触连接的不同状态，从而实现了兴奋性和抑制性突触后效应之间的动态可重构性。所得到的器件仅依赖于突触前或突触后终端的电偏置来实现这种动态可重构性。它在操作特性和生物等效性方面与传统的异突触器件明显不同。该器件模拟了突触的关键特性，如增强和抑制以及尖峰时间依赖性可塑性，用于兴奋性和抑制性响应模式。该器件具有重新配置的特性，有可能在基于硬件的人工神经网络中实现有用的功能。
