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Soft-X-ray microspectroscopy study of TiO2-based resistive switching devices

Soft-X-ray microspectroscopy study of TiO2-based resistive switching devices
Soft-X-ray microspectroscopy study of TiO2-based resistive switching devices
Titanium dioxide (TiO2) has been widely used as resistive switching oxide in random-access memory devices; the resistive switching mechanism is usually attributed to the formation and migration of defects along the TiO2 thin film which result in chemical changes of the oxide, in particular in the formation of highly reduced oxide phases. However, a fully understanding of the atomic-scale resistive switching mechanism and identification of material changes within the oxide has not been achieved.
In this work, we present for the first time a Ti L-edge (450-485 eV) and O K-edge (525-555 eV) Near-Edge X-Ray Absorption Fine Structure Transmission X-Ray Microscopy (NEXAFS-TXM) study on photon transparent cross sections of Pt/TiO2(50nm)/Pt -based devices in different switching states: pristine, high resistive state (HRS) and low resistive state (LRS).
This technique has the capability of performing simultaneously imaging (which allows investigation of morphological changes in the film) and spectroscopy, which allows chemical analysis at nanometric scale of localized regions. Moreover, it has the advantage of being non-destructive, element specific and spatially-resolved. Differences in intensity, width, shape and position of the NEXAFS peaks give detailed information on symmetry around Ti and O, oxidation state and titanium oxide phases formed across the film as a consequence of the switching.
X-ray imaging gives direct evidence of the formation a localized filamentary region in the sample switched into the LRS state. Chemical analysis of the filamentary region and of the surrounding areas at the nanoscale performed by studying simultaneously Ti L-edge and O K-edge NEXAFS spectra shows highly localized reduced TiOx species forming the conductive filament, along with crystallization of amorphous TiO2 in the surrounding region
Carta, Daniela
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Hitchcock, Adam P.
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Guttmann, Peter
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Regoutz, Anna
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Khiat, Ali
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Serb, Alexantrou
30f5ec26-f51d-42b3-85fd-0325a27a792c
Gupta, Isha
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Prodromakis, Themistoklis
7af7ccd9-1fb5-4da5-9f0b-165ae6c8fbe0
Carta, Daniela
9b506203-38a2-4b05-a5a4-61d9e218df47
Hitchcock, Adam P.
a869984b-9f48-426d-9cc0-23a469871679
Guttmann, Peter
ba7d6f2e-60ea-41d9-9aae-24eba5b25059
Regoutz, Anna
5f9fa784-fea8-42f9-949f-4fe7a908f8ce
Khiat, Ali
bf549ddd-5356-4a7d-9c12-eb6c0d904050
Serb, Alexantrou
30f5ec26-f51d-42b3-85fd-0325a27a792c
Gupta, Isha
11f9ea1a-e38a-45d4-930d-96ac78b3d734
Prodromakis, Themistoklis
7af7ccd9-1fb5-4da5-9f0b-165ae6c8fbe0

Carta, Daniela, Hitchcock, Adam P., Guttmann, Peter, Regoutz, Anna, Khiat, Ali, Serb, Alexantrou, Gupta, Isha and Prodromakis, Themistoklis (2015) Soft-X-ray microspectroscopy study of TiO2-based resistive switching devices. Advances in ReRAM: Materials & Interfaces, Greece. 01 Jan - 16 Oct 2015.

Record type: Conference or Workshop Item (Other)

Abstract

Titanium dioxide (TiO2) has been widely used as resistive switching oxide in random-access memory devices; the resistive switching mechanism is usually attributed to the formation and migration of defects along the TiO2 thin film which result in chemical changes of the oxide, in particular in the formation of highly reduced oxide phases. However, a fully understanding of the atomic-scale resistive switching mechanism and identification of material changes within the oxide has not been achieved.
In this work, we present for the first time a Ti L-edge (450-485 eV) and O K-edge (525-555 eV) Near-Edge X-Ray Absorption Fine Structure Transmission X-Ray Microscopy (NEXAFS-TXM) study on photon transparent cross sections of Pt/TiO2(50nm)/Pt -based devices in different switching states: pristine, high resistive state (HRS) and low resistive state (LRS).
This technique has the capability of performing simultaneously imaging (which allows investigation of morphological changes in the film) and spectroscopy, which allows chemical analysis at nanometric scale of localized regions. Moreover, it has the advantage of being non-destructive, element specific and spatially-resolved. Differences in intensity, width, shape and position of the NEXAFS peaks give detailed information on symmetry around Ti and O, oxidation state and titanium oxide phases formed across the film as a consequence of the switching.
X-ray imaging gives direct evidence of the formation a localized filamentary region in the sample switched into the LRS state. Chemical analysis of the filamentary region and of the surrounding areas at the nanoscale performed by studying simultaneously Ti L-edge and O K-edge NEXAFS spectra shows highly localized reduced TiOx species forming the conductive filament, along with crystallization of amorphous TiO2 in the surrounding region

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More information

Accepted/In Press date: 15 October 2015
Venue - Dates: Advances in ReRAM: Materials & Interfaces, Greece, 2015-01-01 - 2015-10-16
Organisations: Nanoelectronics and Nanotechnology

Identifiers

Local EPrints ID: 383974
URI: http://eprints.soton.ac.uk/id/eprint/383974
PURE UUID: ab944f9b-1418-4e4d-b0ac-3a572006dadf

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Date deposited: 19 Nov 2015 11:42
Last modified: 17 Jul 2017 20:08

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Contributors

Author: Daniela Carta
Author: Adam P. Hitchcock
Author: Peter Guttmann
Author: Anna Regoutz
Author: Ali Khiat
Author: Alexantrou Serb
Author: Isha Gupta
Author: Themistoklis Prodromakis

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