In-situ Study of Understanding the Resistive Switching Mechanisms of Nitride-based Memristor Devices

TL;DR

This study investigates the resistive switching mechanisms of nitride-based memristors using in situ TEM and STEM-EELS, revealing defect migration and barrier modulation as key processes, which advances understanding and design of low-energy memory devices.

Contribution

It provides the first in situ microscopic evidence that defect migration modulates resistive states without filament formation in nitride memristors.

Findings

Defects such as oxygen vacancies migrate along grain boundaries under electric field.

Resistive switching occurs via Schottky barrier modulation, not filament formation.

The device demonstrates bipolar switching with reliable repeatability.

Abstract

Interface-type resistive switching (RS) devices with lower operation current and more reliable switching repeatability exhibits great potential in the applications for data storage devices and ultra-low-energy computing. However, the working mechanism of such interface-type RS devices are much less studied compared to that of the filament-type devices, which hinders the design and application of the novel interface-type devices. In this work, we fabricate a metal/TiOx/TiN/Si (001) thin film memristor by using a one-step pulsed laser deposition. In situ transmission electron microscopy (TEM) imaging and current-voltage (I-V) characteristic demonstrate that the device is switched between high resistive state (HRS) and low resistive state (LRS) in a bipolar fashion with sweeping the applied positive and negative voltages. In situ scanning transmission electron microscopy (STEM) experiments with electron energy loss spectroscopy (EELS) reveal that the charged defects (such as oxygen vacancies) can migrate along the intrinsic grain boundaries of TiOx insulating phase under electric field without forming obvious conductive filaments, resulting in the modulation of Schottky barriers at the metal/semiconductor interfaces. The fundamental insights gained from this study presents a novel perspective on RS processes and opens up new technological opportunities for fabricating ultra-low-energy nitride-based memristive devices.