One transistor-two resistive RAM device for realizing bidirectional and analog neuromorphic synapse devices

Abstract

In this paper, we propose a one transistor-two resistive RAM (RRAM) (1T2R) device to overcome the non-ideal switching behavior of artificial synapse devices, such as the unidirectional and abrupt change in the conductance. Our findings reveal that the 1T2R device can exhibit bidirectional conductance changes using unidirectional switching RRAMs. Thus, we introduce a unidirectional but analog switching Cu-based RRAM device (Cu/Cu2-X S/WO3-X/W) having an internal voltage suppressor (Cu2-XS) to realize a bidirectional and analog 1T2R synapse device. The synaptic behaviors of the 1T2R device are calculated using the subthreshold region of an NMOSFET. In addition, we improve the on/off conductance ratio and conductance change linearity owing to the nonlinear current transition characteristics of the subthreshold region. Finally, we demonstrate that an ideal synaptic behavior can be achieved through the 1T2R device even when non-ideal switching RRAM elements are used.

Oxide Memristors for Brain-inspired Computing

“…Hwang 等 [120] 制备了 Cu/Cu2-xS/WO3-x/W 结构忆 阻器，其中 WO3-x 为忆阻层，Cu2-xS 为类似于二极 管的分压器。使用两个该忆阻器和一个晶体管组成 的突触器件可双向可逆调控电导 [121] 。在 HfO2 和 Cu2S 之间插入 Ta 层可有效控制 Cu 离子扩散， 得到 性能稳定的 Cu/HfO2/Ta/Cu2S/W 忆阻器 [122] 。将该忆 阻器用作神经形态突触，可有效提升神经网络的分 类精度。 Yan 等 [123] 利用有序排列的 PbS 量子点控制 [124] 、 ZnO/Ag [125] 、 ZrO2/WS2 [126] 、 LiCoO2/a-Si [127] 等。…”

Resistive Switching in HfO2–x/La0.67Sr0.33MnO3 Heterostructures: An Intriguing Case of Low H-Field Susceptibility of an E-Field Controlled Active Interface

“…This device is also termed a memristor. Although numerous materials have been explored for this beguiling RS application over the years; however, research on the novel materials, device architectures, and interface-engineered functional metal oxide systems is still being very actively pursued for realizing enhanced performance and robust modulation. , Among various random access memory (RAM) alternatives, ReRAM stands out for its simple structure, wide material range, versatility of fabrication, − high endurance and retention, and high-speed operation . Even though the last decade has witnessed exploration of a variety of dielectric materials for ReRAM applications, presently the research on multioxide-interface heterostructures , is on the rise due to the astonishing changes in RS properties encountered at the corresponding interfaces .…”

One Transistor–Two Memristor Based on Amorphous Indium–Gallium–Zinc-Oxide for Neuromorphic Synaptic Devices

“…In this regard, several approaches using a combination of one transistor and two memristors (1T2M) have been proposed. 29 However, they require one select transistor or switch for each cell, which means that one synaptic device is a 2T2M rather than a 1T2M. The resistance switching phenomena of memristors have been observed in various oxide-based materials, such as HfOx, 30−32 TiOx, 33−35 AlOx, 36,37 TaOx, 38,39 and ZnO.…”

“…Therefore, the realization of linearity and symmetry at the device level would be a better solution. In this regard, several approaches using a combination of one transistor and two memristors (1T2M) have been proposed . However, they require one select transistor or switch for each cell, which means that one synaptic device is a 2T2M rather than a 1T2M.…”