Fabrication and investigation of ferroelectric memristors with various synaptic plasticities

In the post-Moore era, neuromorphic computing has been mainly focused on breaking the von Neumann bottlenecks. Memristors have been proposed as a key part of neuromorphic computing architectures, and can be used to emulate the synaptic plasticities of the human brain. Ferroelectric memristors represent a breakthrough for memristive devices on account of their reliable nonvolatile storage, low write/read latency and tunable conductive states. However, among the reported ferroelectric memristors, the mechanisms of resistive switching are still under debate. In addition, there needs to be more research on emulation of the brain synapses using ferroelectric memristors. Herein, Cu/PbZr_0.52Ti_0.48O₃ (PZT)/Pt ferroelectric memristors have been fabricated. The devices are able to realize the transformation from threshold switching behavior to resistive switching behavior. The synaptic plasticities, including excitatory post-synaptic current, paired-pulse facilitation, paired-pulse depression and spike time-dependent plasticity, have been mimicked by the PZT devices. Furthermore, the mechanisms of PZT devices have been investigated by first-principles calculations based on the interface barrier and conductive filament models. This work may contribute to the application of ferroelectric memristors in neuromorphic computing systems.     

基于二维材料MXene的仿神经突触忆阻器的制备和长/短时程突触可塑性的实现

兼具长时程可塑性与短时程可塑性的电子突触被认为是类脑计算系统的重要基础.将一种新型二维材料MXene应用到忆阻器中,制备了基于Cu/MXene/SiO_2/W的仿神经突触忆阻器.结果表明, Cu/MXene/SiO_2/W忆阻器成功实现了稳定的双极性模拟阻态切换,同时成功模拟了生物突触短时程可塑性的双脉冲易化功能和长时程可塑性的长期增强/抑制行为,其中双脉冲易化的易化指数与脉冲间隔时间相关. Cu/MXene/SiO_2/W忆阻器的突触仿生特性,归功于MXene辅助的Cu离子电导丝形成与破灭的类突触响应机理.由于Cu/MXene/SiO_2/W忆阻器兼具长时程可塑性与短时程可塑性,其在突触仿生电子学和类脑智能领域将会具有巨大的应用前景.     

基于石墨烯-钙钛矿量子点场效应晶体管的光电探测器

以等离子增强化学气相沉积法制备的石墨烯作为导电沟道材料,将其与无机CsPbI_3钙钛矿量子点结合,设计并制备了石墨烯-钙钛矿量子点场效应晶体管光电探测器.研究和分析了石墨烯作为场效应晶体管的电学特性及其与钙钛矿量子点结合作为光电探测器的光电特性.结果表明,石墨烯在场效应晶体管中表现出良好的电学性质,其与钙钛矿量子点的结合对波长为400 nm的光辐射具有明显的光响应,在光强为12μW时器件光生电流最大为64μA,响应率达6.4 A·W~(-1),对应的光电导增益和探测率分别为3.7×10~4,6×10~7Jones(1 Jones=1 cm·Hz~(1/2)·W~(-1)).     

W/SiO2基太阳光谱选择性吸收薄膜的制备和表征

采用磁控溅射镀膜仪制备了基于过渡金属W和介质SiO_2的6层薄膜样品,膜系结构为Cu (100.0nm)/SiO_2(63.5nm)/W(11.0nm)/SiO_2(60.0nm)/W(5.4nm)/SiO_2(75.5nm)。在250～2500nm的波长范围内,该样品的太阳光吸收率为95.3%,且在400℃低真空(6Pa)条件下退火72h之后,样品的反射光谱特性变化较小,证明了该样品具有极高的热稳定性。使用红外热成像仪对样品的红外辐射特性进行了在位实时表征,结果表明样品具有低辐射特性。这些优良的特性有利于该样品在太阳能光热转换中的应用。