Bipolar and Complementary Resistive Switching Characteristics and Neuromorphic System Simulation in a Pt/ZnO/TiN Synaptic Device.

Sobia Ali Khan,Hyungjin Kim,Sungjun Kim,Chandreswar Mahata,Geun Ho Lee,Muhammad Ismail

doi:10.3390/nano11020315

Sobia Ali Khan, Hyungjin Kim + Show 4 more

Open Access

https://doi.org/10.3390/nano11020315

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Abstract

In this work, a ZnO-based resistive switching memory device is characterized by using simplified electrical conduction models. The conventional bipolar resistive switching and complementary resistive switching modes are accomplished by tuning the bias voltage condition. The material and chemical information of the device stack including the interfacial layer of TiON is well confirmed by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) analysis. The device exhibits uniform gradual bipolar resistive switching (BRS) with good endurance and self-compliance characteristics. Moreover, complementary resistive switching (CRS) is achieved by applying the compliance current at negative bias and increasing the voltage at positive bias. The synaptic behaviors such as long-term potentiation and long-term depression are emulated by applying consecutive pulse input to the device. The CRS mode has a higher array size in the cross-point array structure than the BRS mode due to more nonlinear I–V characteristics in the CRS mode. However, we reveal that the BRS mode shows a better pattern recognition rate than the CRS mode due to more uniform conductance update.

Highlights

Published: 27 January 2021Resistive random-access memory (RRAM) is one of the strongest candidates for the next-generation nonvolatile memory technology due to low power consumption [1], fast switching speed [2], good complementary metal–oxide–semiconductor (CMOS) compatibility [3,4,5], and high scalability [6]
RRAM has been developed to focus on its applications such as high-density memory, embedded memory, and neuromorphic system
Pt top electrode was deposited on the ZnO film by direct current (DC) magnetron sputtering at room temperature (RT) to form a Pt/ZnO/TiN RRAM device

Summary

Introduction

Resistive random-access memory (RRAM) is one of the strongest candidates for the next-generation nonvolatile memory technology due to low power consumption [1], fast switching speed [2], good complementary metal–oxide–semiconductor (CMOS) compatibility [3,4,5], and high scalability [6]. RRAM has been developed to focus on its applications such as high-density memory, embedded memory, and neuromorphic system. For storage class memory and embedded memory applications, the fast switching speed of RRAM is attractive. Among a lot of resistor materials, the metal oxides such as HfO2 , TaOx , TiO2 , ZrO, and ZnO attract huge interest due to good resistive switching performance such as endurance, retention, high switching speed, and relatively good variability [10]. The unipolar resistive switching (URS) and homogeneous BRS were controllable by the compliance current in a Pt/ZnO/Pt device [12]

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