Polarization-Dominated Internal Timing Mechanism in a Ferroelectric Second-Order Memristor
Polarization-Dominated Internal Timing Mechanism in a Ferroelectric Second-Order Memristor
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DOI：
10.1103/physrevapplied.19.014054
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发表时间：
2023-01-19
影响因子：
4.6
通讯作者：
Liu, Jun -Ming
中科院分区：
文献类型：
--
作者：
Li, Wenjie;Fan, Zhen;Liu, Jun -Ming
二阶忆阻器因其表现出类钙动力学的能力而被认为是理想的突触模拟器。最近，铁电二阶忆阻器被开发出来，但由于难以直接测量这些器件中的极化，它们的时间电导演化是否与极化动力学相关仍然不清楚。这个问题在这里解决，通过使用铁电二极管（FD），显示二阶忆阻行为和良好的形状极化电压回线。研究表明，FD中的电阻状态变化是由极化控制的肖特基发射引起的极化切换触发的。此外，还观察到电导衰减和极化弛豫的同时发生，并定量地证明了它们之间的相关性，表明电导衰减是由极化弛豫引起的肖特基势垒高度的增加引起的.使用极化弛豫作为内部定时机制，我们的基于FD的二阶忆阻器忠实地模拟各种突触功能，其中短期可塑性是不可或缺的，包括兴奋性突触后电流，成对脉冲促进，从短期可塑性到长期可塑性的过渡，学习经验和联想学习。我们的研究不仅揭示了基于FD的二阶忆阻器中偏振主导的内部定时机制，而且还表明这种设备是生物现实神经形态系统的一个有前途的构建模块。
Second-order memristors are considered as ideal synaptic emulators for their capability of exhibiting Ca2+-like dynamics. Recently, ferroelectric second-order memristors were developed, but whether their temporal conductance evolution is related to polarization dynamics remains unclear owing to the difficulty in directly measuring polarization in these devices. This issue is addressed here by using a ferroelectric diode (FD) that shows both second-order memristive behavior and well-shaped polarization-voltage hys-teresis loops. It is demonstrated that the resistance-state change in the FD is triggered by polarization switching, arising from polarization-controlled Schottky emission. Moreover, concurrent conductance decay and polarization relaxation are observed, and their correlation is quantitatively evidenced, sug-gesting that conductance decay is caused by the polarization-relaxation-induced increase in the Schottky barrier height. Using polarization relaxation as an internal timing mechanism, our FD-based second-order memristor faithfully emulates various synaptic functions, where short-term plasticity is indispensable, including excitatory postsynaptic current, paired-pulse facilitation, the transition from short-term plas-ticity to long-term plasticity, learning experience, and associative learning. Our study not only reveals a polarization-dominated internal timing mechanism in the FD-based second-order memristor, but also demonstrates that such a device is a promising building block for biorealistic neuromorphic systems.