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Tackling Disorder in γ-Ga2 O3

Ratcliff, Laura E; Oshima, Takayoshi; Nippert, Felix; Janzen, Benjamin M; Kluth, Elias; Goldhahn, Rüdiger; Feneberg, Martin; ... Regoutz, Anna; + view all (2022) Tackling Disorder in γ-Ga2 O3. Advanced Materials , Article e2204217. 10.1002/adma.202204217. (In press). Green open access

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Ga2 O3 and its polymorphs are attracting increasing attention. The rich structural space of polymorphic oxide systems such as Ga2 O3 offers potential for electronic structure engineering, which is of particular interest for a range of applications, such as power electronics. γ-Ga2 O3 presents a particular challenge across synthesis, characterisation, and theory due to its inherent disorder and resulting complex structure - electronic structure relationship. Here, density functional theory is used in combination with a machine learning approach to screen nearly one million potential structures, thereby developing a robust atomistic model of the γ-phase. Theoretical results are compared with surface and bulk sensitive soft and hard X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, spectroscopic ellipsometry, and photoluminescence excitation spectroscopy experiments representative of the occupied and unoccupied states of γ-Ga2 O3 . The first onset of strong absorption at room temperature is found at 5.1 eV from spectroscopic ellipsometry, which agrees well with the excitation maximum at 5.17 eV obtained by PLE spectroscopy, where the latter shifts to 5.33 eV at 5 K. This work presents a leap forward in the treatment of complex, disordered oxides and is a crucial step towards exploring how their electronic structure can be understood in terms of local coordination and overall structure. This article is protected by copyright. All rights reserved.

Type: Article
Title: Tackling Disorder in γ-Ga2 O3
Location: Germany
Open access status: An open access version is available from UCL Discovery
DOI: 10.1002/adma.202204217
Publisher version: https://doi.org/10.1002/adma.202204217
Language: English
Additional information: Copyright © 2022 The Authors. This is an open access article under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Keywords: X-ray photoelectron spectroscopy, density functional theory, disorder, gallium oxide, machine learning, photoluminescence excitation spectroscopy, ultra wide band gap
UCL classification: UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry
UCL > Provost and Vice Provost Offices > UCL BEAMS
URI: https://discovery.ucl.ac.uk/id/eprint/10153522
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