The University of Southampton
University of Southampton Institutional Repository

Spatially resolved TiOx phases in switched RRAM devices using soft X-ray spectromicroscopy

Spatially resolved TiOx phases in switched RRAM devices using soft X-ray spectromicroscopy
Spatially resolved TiOx phases in switched RRAM devices using soft X-ray spectromicroscopy
Reduction in metal-oxide thin films has been suggested as the key mechanism responsible for forming conductive phases within solid-state memory devices, enabling their resistive switching capacity. The quantitative spatial identification of such conductive regions is a daunting task, particularly for metal-oxides capable of exhibiting multiple phases as in the case of TiOx. Here, we spatially resolve and chemically characterize distinct TiOx phases in localized regions of a TiOx–based memristive device by combining full-field transmission X-ray microscopy with soft X-ray spectroscopic analysis that is performed on lamella samples. We particularly show that electrically pre-switched devices in low-resistive states comprise reduced disordered phases with O/Ti ratios around 1.37 that aggregate in a ~ 100 nm highly localized region electrically conducting the top and bottom electrodes of the devices. We have also identified crystalline rutile and orthorhombic-like TiO2 phases in the region adjacent to the main reduced area, suggesting that the temperature increases locally up to 1000 K, validating the role of Joule heating in resistive switching. Contrary to previous studies, our approach enables to simultaneously investigate morphological and chemical changes in a quantitative manner without incurring difficulties imposed by interpretation of electron diffraction patterns acquired via conventional electron microscopy techniques.
1-10
Carta, D.
120de978-2aaa-4b4d-bf5f-3625c503040d
Hitchcock, A.
437d220b-a94e-4bf3-b5ef-1a5fdc1ec1c5
Guttmann, P.
27f5fae8-b0cd-4527-96de-2dad5b70443c
Regoutz, A.
f10acbf6-a56e-4193-88d5-5167f3ecb385
Khiat, A.
bf549ddd-5356-4a7d-9c12-eb6c0d904050
Serb, A.
30f5ec26-f51d-42b3-85fd-0325a27a792c
Gupta, I.
11f9ea1a-e38a-45d4-930d-96ac78b3d734
Prodromakis, T.
d58c9c10-9d25-4d22-b155-06c8437acfbf
Carta, D.
120de978-2aaa-4b4d-bf5f-3625c503040d
Hitchcock, A.
437d220b-a94e-4bf3-b5ef-1a5fdc1ec1c5
Guttmann, P.
27f5fae8-b0cd-4527-96de-2dad5b70443c
Regoutz, A.
f10acbf6-a56e-4193-88d5-5167f3ecb385
Khiat, A.
bf549ddd-5356-4a7d-9c12-eb6c0d904050
Serb, A.
30f5ec26-f51d-42b3-85fd-0325a27a792c
Gupta, I.
11f9ea1a-e38a-45d4-930d-96ac78b3d734
Prodromakis, T.
d58c9c10-9d25-4d22-b155-06c8437acfbf

Carta, D., Hitchcock, A., Guttmann, P., Regoutz, A., Khiat, A., Serb, A., Gupta, I. and Prodromakis, T. (2016) Spatially resolved TiOx phases in switched RRAM devices using soft X-ray spectromicroscopy. Scientific Reports, 6, 1-10. (doi:10.1038/srep21525).

Record type: Article

Abstract

Reduction in metal-oxide thin films has been suggested as the key mechanism responsible for forming conductive phases within solid-state memory devices, enabling their resistive switching capacity. The quantitative spatial identification of such conductive regions is a daunting task, particularly for metal-oxides capable of exhibiting multiple phases as in the case of TiOx. Here, we spatially resolve and chemically characterize distinct TiOx phases in localized regions of a TiOx–based memristive device by combining full-field transmission X-ray microscopy with soft X-ray spectroscopic analysis that is performed on lamella samples. We particularly show that electrically pre-switched devices in low-resistive states comprise reduced disordered phases with O/Ti ratios around 1.37 that aggregate in a ~ 100 nm highly localized region electrically conducting the top and bottom electrodes of the devices. We have also identified crystalline rutile and orthorhombic-like TiO2 phases in the region adjacent to the main reduced area, suggesting that the temperature increases locally up to 1000 K, validating the role of Joule heating in resistive switching. Contrary to previous studies, our approach enables to simultaneously investigate morphological and chemical changes in a quantitative manner without incurring difficulties imposed by interpretation of electron diffraction patterns acquired via conventional electron microscopy techniques.

Text
Carta_Scientific Reports-1.pdf - Accepted Manuscript
Available under License Creative Commons Attribution.
Download (439kB)
Text
srep21525.pdf - Version of Record
Available under License Creative Commons Attribution.
Download (1MB)

More information

Accepted/In Press date: 26 January 2016
e-pub ahead of print date: 19 February 2016
Published date: 19 February 2016
Organisations: Nanoelectronics and Nanotechnology

Identifiers

Local EPrints ID: 386368
URI: https://eprints.soton.ac.uk/id/eprint/386368
PURE UUID: dbdd70e5-c998-4667-8ce7-168d2f614752
ORCID for T. Prodromakis: ORCID iD orcid.org/0000-0002-6267-6909

Catalogue record

Date deposited: 02 Feb 2016 09:24
Last modified: 03 Dec 2019 01:36

Export record

Altmetrics

Contributors

Author: D. Carta
Author: A. Hitchcock
Author: P. Guttmann
Author: A. Regoutz
Author: A. Khiat
Author: A. Serb
Author: I. Gupta
Author: T. Prodromakis ORCID iD

University divisions

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of https://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×