Zirconium Doping of Tantalum Oxide for Increased Vacancy Mobility in Resistive Switching Bilayer Structures

Date of Award

12-1-2023

Degree Name

M.S. in Electrical Engineering

Department

Department of Electrical and Computer Engineering

Advisor/Chair

Advisor: Guru Subramanyam

Abstract

Memristors are among the leading devices for non-volatile memory applications due to its in-memory computing capability, power efficiency and high endurance, as well as the speed at which memory states can be written. Tantalum oxide is currently one of the most promising materials in memristor design. Tantalum oxide based memristor devices operate via oxygen vacancy migration in the TaOx layer forming a filament which then allows current flow once formed. Due to the migration of the vacancies through the material to form this chain, there is permanent structural damage to the device over the course of operation which eventually results in reduced performance of the devices and less change between the SET/RESET states. In this paper, we analyze the impact of zirconium doping concentrations on oxygen vacancy migration by studying the electric field required to induce switching in the devices and device endurance. We test the power efficiency and ON/OFF resistance ratios of numerous TiN/TaOx/Ta/TiN devices made with zirconium oxide doping layers. The results are then analyzed to understand the effects of the TaOx/ZrO2 bilayer structure and the impact on the total power efficiency and endurance of the devices. The devices did show increased conductivity but switching performance and endurance were reduced. TEM imaging was performed to determine the cause, but no definitive cause could be identified.

Keywords

Memristor, ReRAM, Thin films, resistive switching, memory, neuromorphic, computing

Rights Statement

Copyright © 2023, author.

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