Voltage Amplitude-Controlled Synaptic Plasticity from Complementary Resistive Switching in Alloying HfOx with AlOx-Based RRAM

Hojeong Ryu,Junhyeok Choi,Sungjun Kim

doi:10.3390/met10111410

Abstract

In this work, the synaptic plasticity from complementary resistive switching in a HfAlOx-based resistive memory device was emulated by a direct current (DC) voltage sweep, current sweep, and pulse transient. The alloyed HfAlOx dielectric was confirmed by X-ray photoelectron spectroscopy analysis. The negative differential resistance observed before the forming and set processes can be used for interface resistive switching with a low current level. Complementary resistive switching is obtained after the forming process at a negative bias. This unique resistive switching is also suitable for synaptic device applications in which the reset process occurs after an additional set process. The current sweep mode provides more clear information on the complementary resistive switching. Multiple current states are achieved by controlling the amplitude of the set and reset voltages under DC sweep mode. The potentiation and depression characteristics are mimicked by varying the pulse voltage amplitude for synaptic device application in a neuromorphic system. Finally, we demonstrate spike-timing-dependent plasticity by tuning the timing differences between pre-spikes and post-spikes.

Highlights

The von Neumann bottleneck makes the memory access time delayed because of the separation of the computing part and memory part in modern complementary metal-oxide-semiconductor (CMOS) computing systems
The results indicate that the multi-level cells (MLC) can be implemented by just the voltage amplitude in the positive bias of Complementary resistive switching (CRS)
Voltage-controlled spike-timing-dependent plasticity (STDP) was demonstrated in a Pt/HfAlOx /TiN memristor device

Summary

Introduction

The von Neumann bottleneck makes the memory access time delayed because of the separation of the computing part and memory part in modern complementary metal-oxide-semiconductor (CMOS) computing systems. In the era of big data, more energy efficient and faster computing systems are needed to overcome the limitations of von Neumann architecture. In-memory computing processing is the promising technology, which, unlike conventional computing, loads and uses all the data into memory [1]. Oxide-based resistive random-access memory (RRAM) is very promising due to its stable and reliable resistive-switching properties such as good variability, long program/erase cycle endurance, long data retention, and complementary metal-oxide-semiconductor (CMOS) compatibility [13]. HfOx is one of the most popular resistive-switching materials due Metals 2020, 10, 1410; doi:10.3390/met10111410 www.mdpi.com/journal/metals

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Results

Conclusion