Two-dimensional confinement of excitons at the interface in nonpolar MgZnO/ZnO heterostructures

Zakria, M; Rogers, DJ; Scola, J; Zhu, L; Lockrey, M; Bove, P; Sandana, EV; Teherani, FH; Phillips, MR; Ton-That, C

Two-dimensional confinement of excitons at the interface in nonpolar MgZnO/ZnO heterostructures

Zakria, M Rogers, DJ Scola, J Zhu, L Lockrey, M

Bove, P Sandana, EV Teherani, FH Phillips, MR Ton-That, C

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Publisher:: AMER PHYSICAL SOC
Publication Type:: Journal Article
Citation:: Physical Review Materials, 2022, 6, (3)
Issue Date:: 2022-03-01

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Field	Value	Language
dc.contributor.author	Zakria, M
dc.contributor.author	Rogers, DJ
dc.contributor.author	Scola, J
dc.contributor.author	Zhu, L
dc.contributor.author	Lockrey, M https://orcid.org/0000-0002-0050-2858
dc.contributor.author	Bove, P
dc.contributor.author	Sandana, EV
dc.contributor.author	Teherani, FH
dc.contributor.author	Phillips, MR
dc.contributor.author	Ton-That, C https://orcid.org/0000-0003-3276-1739
dc.date.accessioned	2023-02-01T02:31:06Z
dc.date.available	2023-02-01T02:31:06Z
dc.date.issued	2022-03-01
dc.identifier.citation	Physical Review Materials, 2022, 6, (3)
dc.identifier.issn	2475-9953
dc.identifier.issn	2475-9953
dc.identifier.uri	http://hdl.handle.net/10453/165748
dc.description.abstract	We report on the polarity-dependent excitonic emission at the interface in MgZnO/ZnO heterostructures grown on both polar and nonpolar ZnO single-crystal substrates. Structural and morphological analyses confirm that the heterostructures grow homoepitaxially on nonpolar m-plane and a-plane crystal substrates. The nonpolar heterostructures are investigated by depth-resolved cathodoluminescence spectroscopy revealing an excitonic interface emission centered at 3.12 eV, identified as the H-band signature of indirect excitons. These results reveal the formation of robust indirect excitons confined at the MgZnO/ZnO interface due to the presence of an epitaxially strained interfacial layer near the interface in the MgZnO, which is confirmed by high-order X-ray diffraction. It is also found that the H-band emission originates from the self-absorption of the ZnO free exciton emission in the proximity of the interface. Temperature-dependent studies of the H band yields a thermal activation energy of 47 meV for the indirect exciton in the nonpolar heterojunctions. This activation energy is the largest among all free and bound excitons in ZnO and is much higher than the values found in AlGaN/GaN and MgZnO/ZnO/sapphire hetrostructures. Our findings indicate that the optical properties of nonpolar heterostructures are strongly influenced by the piezoelectric effect.
dc.language	English
dc.publisher	AMER PHYSICAL SOC
dc.relation	http://purl.org/au-research/grants/arc/DP210101146
dc.relation.ispartof	Physical Review Materials
dc.relation.isbasedon	10.1103/PhysRevMaterials.6.035202
dc.rights	info:eu-repo/semantics/closedAccess
dc.title	Two-dimensional confinement of excitons at the interface in nonpolar MgZnO/ZnO heterostructures
dc.type	Journal Article
utslib.citation.volume	6
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	closed_access	*
dc.date.updated	2023-02-01T02:31:04Z
pubs.issue	3
pubs.publication-status	Published
pubs.volume	6
utslib.citation.issue	3

Abstract:

We report on the polarity-dependent excitonic emission at the interface in MgZnO/ZnO heterostructures grown on both polar and nonpolar ZnO single-crystal substrates. Structural and morphological analyses confirm that the heterostructures grow homoepitaxially on nonpolar m-plane and a-plane crystal substrates. The nonpolar heterostructures are investigated by depth-resolved cathodoluminescence spectroscopy revealing an excitonic interface emission centered at 3.12 eV, identified as the H-band signature of indirect excitons. These results reveal the formation of robust indirect excitons confined at the MgZnO/ZnO interface due to the presence of an epitaxially strained interfacial layer near the interface in the MgZnO, which is confirmed by high-order X-ray diffraction. It is also found that the H-band emission originates from the self-absorption of the ZnO free exciton emission in the proximity of the interface. Temperature-dependent studies of the H band yields a thermal activation energy of 47 meV for the indirect exciton in the nonpolar heterojunctions. This activation energy is the largest among all free and bound excitons in ZnO and is much higher than the values found in AlGaN/GaN and MgZnO/ZnO/sapphire hetrostructures. Our findings indicate that the optical properties of nonpolar heterostructures are strongly influenced by the piezoelectric effect.

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http://hdl.handle.net/10453/165748