Bandgap narrowing and hole self-trapping reduction in Ga<inf>2</inf>O<inf>3</inf> by Bi<inf>2</inf>O<inf>3</inf> alloying

Matar, F; Shi, YL; Ling, FCC; Salih, A; Irvine, CP; De Silva, S; Phillips, MR; Ton-That, C

Bandgap narrowing and hole self-trapping reduction in Ga<inf>2</inf>O<inf>3</inf> by Bi<inf>2</inf>O<inf>3</inf> alloying

Matar, F Shi, YL Ling, FCC Salih, A Irvine, CP De Silva, S Phillips, MR Ton-That, C

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Publisher:: ELSEVIER SCIENCE SA
Publication Type:: Journal Article
Citation:: Journal of Alloys and Compounds, 2023, 960
Issue Date:: 2023-10-15

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Field	Value	Language
dc.contributor.author	Matar, F
dc.contributor.author	Shi, YL
dc.contributor.author	Ling, FCC
dc.contributor.author	Salih, A
dc.contributor.author	Irvine, CP
dc.contributor.author	De Silva, S
dc.contributor.author	Phillips, MR
dc.contributor.author	Ton-That, C https://orcid.org/0000-0003-3276-1739
dc.date.accessioned	2024-02-13T01:07:27Z
dc.date.available	2024-02-13T01:07:27Z
dc.date.issued	2023-10-15
dc.identifier.citation	Journal of Alloys and Compounds, 2023, 960
dc.identifier.issn	0925-8388
dc.identifier.issn	1873-4669
dc.identifier.uri	http://hdl.handle.net/10453/175630
dc.description.abstract	Ga2O3 is an emerging material with attractive electrical properties for improving the performance of high-voltage power electronics, and it is widely accepted that engineering its band edge energies will expand its applications, especially for bipolar devices. In this work, monoclinic phase (BixGa1−x)2O3 ternary alloys are fabricated on c-plane sapphire via magnetron co-sputtering of Ga2O3 and Bi2O3. The bandgap of Ga2O3 is found to decrease from 4.97 to 4.78 eV by alloying with a Bi x-fraction of 0.04, consistent with the theoretical prediction that alloying with Bi2O3 causes the up-shift of the valence band. Concurrent temperature-resolved cathodoluminescence (CL) measurements of the Ga2O3 and (Bi0.04Ga0.96)2O3 are employed to investigate their intrinsic ultraviolet (UV) luminescence and defect-related visible bands with increasing temperature from 80 K. The CL results reveal a more rapid thermal quenching of the self-trapped hole (STH) emission with an activation energy of only 32 meV, suggesting that alloying with Bi2O3 lowers the self-trapping energy for holes. Temperature-dependent electrical measurements reveal the conductivity of the (Bi0.04Ga0.96)2O3 film is one order of magnitude lower than that of the undoped Ga2O3 counterpart; however, both possess an electrical activation energy of ∼ 26 meV, likely associated with an impurity-related shallow donor. The low electrical conductivity of (Bi0.04Ga0.96)2O3 can be attributed to the compensation of shallow donors by acceptors activated by the Bi2O3-induced upward shift of the valence band edge. The frequency-dependent conduction and ionic polarization mechanisms up to 107 Hz are found to be identical for Ga2O3 and (Bi0.04Ga0.96)2O3, indicating that the conduction in this ternary alloy does not involve the activation of Bi acceptors.
dc.language	English
dc.publisher	ELSEVIER SCIENCE SA
dc.relation	http://purl.org/au-research/grants/arc/DP210101146
dc.relation.ispartof	Journal of Alloys and Compounds
dc.relation.isbasedon	10.1016/j.jallcom.2023.170983
dc.rights	info:eu-repo/semantics/embargoedAccess
dc.subject	0204 Condensed Matter Physics, 0912 Materials Engineering, 0914 Resources Engineering and Extractive Metallurgy
dc.subject.classification	Materials
dc.subject.classification	4016 Materials engineering
dc.subject.classification	5104 Condensed matter physics
dc.title	Bandgap narrowing and hole self-trapping reduction in Ga<inf>2</inf>O<inf>3</inf> by Bi<inf>2</inf>O<inf>3</inf> alloying
dc.type	Journal Article
utslib.citation.volume	960
utslib.for	0204 Condensed Matter Physics
utslib.for	0912 Materials Engineering
utslib.for	0914 Resources Engineering and Extractive Metallurgy
pubs.organisational-group	University of Technology Sydney
pubs.organisational-group	University of Technology Sydney/Faculty of Science
pubs.organisational-group	University of Technology Sydney/Faculty of Science/School of Mathematical and Physical Sciences
utslib.copyright.status	embargoed	*
utslib.copyright.embargo	2025-10-01T00:00:00+1000Z
dc.date.updated	2024-02-13T01:07:26Z
pubs.publication-status	Published
pubs.volume	960

Abstract:

Ga2O3 is an emerging material with attractive electrical properties for improving the performance of high-voltage power electronics, and it is widely accepted that engineering its band edge energies will expand its applications, especially for bipolar devices. In this work, monoclinic phase (BixGa1−x)2O3 ternary alloys are fabricated on c-plane sapphire via magnetron co-sputtering of Ga2O3 and Bi2O3. The bandgap of Ga2O3 is found to decrease from 4.97 to 4.78 eV by alloying with a Bi x-fraction of 0.04, consistent with the theoretical prediction that alloying with Bi2O3 causes the up-shift of the valence band. Concurrent temperature-resolved cathodoluminescence (CL) measurements of the Ga2O3 and (Bi0.04Ga0.96)2O3 are employed to investigate their intrinsic ultraviolet (UV) luminescence and defect-related visible bands with increasing temperature from 80 K. The CL results reveal a more rapid thermal quenching of the self-trapped hole (STH) emission with an activation energy of only 32 meV, suggesting that alloying with Bi2O3 lowers the self-trapping energy for holes. Temperature-dependent electrical measurements reveal the conductivity of the (Bi0.04Ga0.96)2O3 film is one order of magnitude lower than that of the undoped Ga2O3 counterpart; however, both possess an electrical activation energy of ∼ 26 meV, likely associated with an impurity-related shallow donor. The low electrical conductivity of (Bi0.04Ga0.96)2O3 can be attributed to the compensation of shallow donors by acceptors activated by the Bi2O3-induced upward shift of the valence band edge. The frequency-dependent conduction and ionic polarization mechanisms up to 107 Hz are found to be identical for Ga2O3 and (Bi0.04Ga0.96)2O3, indicating that the conduction in this ternary alloy does not involve the activation of Bi acceptors.

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