基于MoS2 FET器件BTI效应对突触传递中神经递质释放的模拟研究

The Signal transmission between neurons in the brain is completed through synaptic transmission, which determined by the release of neurotransmitters. Neurotransmitters not only have short-term and long-term effects on the synapses, but also control different functions of the brain. The research on the process of the neurotransmitters release and its effect on the synaptic transmission, lays a foundation for the development of solid-state electronic devices based on synapses and artificial intelligence machines based on neuromorphic systems, and provides scientific support for understanding the brain functions related to the release of neurotransmitters and treating the diseases caused by the abnormal release of neurotransmitters. .In this project, the release of neurotransmitter in the synaptic transmission was correlated with the bias temperature instability (BTI) reliability issue of MoS2 (Molybdenum disulfide) FET device. Based on the hysteresis characteristic of MoS2 FET, the process of neurotransmitters release under single action potential excitation was simulated and modeled. On this basis, based on the degradation mechanism of BTI effect, the process of neurotransmitters release under multiple action potentials is mimicked, and the model is established to characterize the time-dependent effect of neurotransmitters release, for predicting the influence of neurotransmitters release on the behavior of synapses. Furthermore, based on the recovery mechanism of BTI effect, the inhibitory process of abnormal neurotransmitters release is mimicked, with the corresponding model established for evaluating the inhibitory means. The device-level model of neurotransmitters release characteristics established by this work can realize the regulation of the synaptic transmission process, and provide a theoretical basis for the development of solid-state electronic devices based on neuronal synapses and the development of neuromorphic systems. In addition, the experiments and modeling of the MoS2 FET hysteresis and BTI effect are also beneficial to the development of high-reliability two-dimensional channel FET devices suitable for future 5 nm and below technology nodes.

大脑中神经元之间的信号传输是通过突触传递来完成的，而神经递质的释放是控制突触传递的关键，神经递质不仅对突触产生短期或长期的影响，还控制着大脑不同的功能。对神经递质释放过程及其对突触传递作用的研究，可以为研制基于神经元突触的固态电子器件、开发基于神经形态系统的人工智能机器奠定基础，同时也为科学认识与神经递质释放相关的脑部功能、治疗神经递质异常释放导致的疾病提供助力。.本项目将突触传递中神经递质的释放与MoS2 FET器件BTI可靠性问题进行关联，基于MoS2 FET迟滞特性对单个动作电位激励下的神经递质释放过程进行模拟与建模；基于BTI效应的退化机制对多个动作电位激励下的神经递质释放过程进行模拟，建立模型以表征神经递质释放的经时效应，实现对突触传递受到神经递质释放影响的预测；更进一步基于BTI效应的恢复机制，针对神经递质异常释放的抑制过程进行模拟，建立相应模型以实现对抑制手段的评估。此项工作所建立的可仿生神经递质释放特性的器件级模型，能够实现对神经突触传递过程的调控，从而为研制基于神经元突触的固态电子器件及开发神经形态系统提供理论基础，此外针对MoS2 FET迟滞现象与BTI效应所进行的实验和建模的工作，也有利于研制适应于未来5nm及以下技术节点的高可靠性二维沟道FET器件。

随着集成电路不断朝向微型化发展，器件特征尺寸的缩小带来的量子效应和热损耗问题将达到理论极限，作为场效应晶体管（FET）中的绝缘栅极材料和沟道材料，二硫化钼（MoS2）有望突破摩尔定律限制取代硅材料成为未来晶体管制造的替代材料，然而MoS2基器件理论体系仍不成熟，并且MoS2 FET的沟道与栅介质界面或栅介质层中的电荷和缺陷同样导致了阈值电压漂移等可靠性问题。本项目首先完成了MoS2 FET器件的制备，然后结合实验和仿真分析对MoS2 FET器件迟滞效应的产生机制进行深入剖析，并且基于迟滞效应的机制和实验分析的结果对器件进行了结构优化和性能提升，最后针对BTI应力下的退化和恢复效应进行了实验研究，阐明了MoS2 FET器件BTI可靠性问题的机理并构建了器件参数退化模型。项目工作为高性能MoS2 FET的器件结构优化和性能提升方面提供了理论和实验支撑。