An ionic polymer route to a stable unpinning of the Fermi level of highly doped graphene

Pradeepkumar, A; Yang, Y; Castañeda, E; Angel, FA; Iacopi, F

An ionic polymer route to a stable unpinning of the Fermi level of highly doped graphene

Pradeepkumar, A Yang, Y

Castañeda, E Angel, FA Iacopi, F

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Publisher:: AIP Publishing
Publication Type:: Journal Article
Citation:: Journal of Applied Physics, 2025, 137, (22)
Issue Date:: 2025-06-14

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Field	Value	Language
dc.contributor.author	Pradeepkumar, A
dc.contributor.author	Yang, Y https://orcid.org/0000-0001-7439-2156
dc.contributor.author	Castañeda, E
dc.contributor.author	Angel, FA
dc.contributor.author	Iacopi, F https://orcid.org/0000-0002-3196-0990
dc.date.accessioned	2025-08-30T14:33:56Z
dc.date.available	2025-08-30T14:33:56Z
dc.date.issued	2025-06-14
dc.identifier.citation	Journal of Applied Physics, 2025, 137, (22)
dc.identifier.issn	0021-8979
dc.identifier.issn	1089-7550
dc.identifier.uri	http://hdl.handle.net/10453/189529
dc.description.abstract	Epitaxial graphene on cubic silicon carbide on silicon could enable unique optical metasurface devices seamlessly integrated with CMOS technologies. However, one of the most promising methods to obtain large-scale epitaxial graphene on this challenging system typically leads to a highly p-type-doped graphene with a Fermi level pinned at ∼0.55 eV below the Dirac point. Hence, the use of conventional gate dielectric materials such as SiO<inf>2</inf> and Si<inf>3</inf>N<inf>4</inf> precludes the tuning of the graphene carrier concentration. We demonstrate that this limitation can be overcome with the use of polyethyleneimine (PEI) as a gate dielectric material for graphene field-effect transistors. We achieve significant tuning of the graphene's Fermi level, enabling ambipolar operation exceeding a 3 eV window. In addition, we demonstrate that excellent stability of the PEI-based devices can be achieved, thanks to the addition of a thin protective oxide film. These findings highlight the potential of ionic polymers for advancing reconfigurable graphene-based devices for photonic applications.
dc.language	English
dc.publisher	AIP Publishing
dc.relation	http://purl.org/au-research/grants/arc/CE200100010
dc.relation.ispartof	Journal of Applied Physics
dc.relation.isbasedon	10.1063/5.0271357
dc.rights	info:eu-repo/semantics/openAccess
dc.subject	01 Mathematical Sciences, 02 Physical Sciences, 09 Engineering
dc.subject.classification	Applied Physics
dc.subject.classification	40 Engineering
dc.subject.classification	49 Mathematical sciences
dc.subject.classification	51 Physical sciences
dc.title	An ionic polymer route to a stable unpinning of the Fermi level of highly doped graphene
dc.type	Journal Article
utslib.citation.volume	137
utslib.for	01 Mathematical Sciences
utslib.for	02 Physical Sciences
utslib.for	09 Engineering
pubs.organisational-group	University of Technology Sydney
pubs.organisational-group	University of Technology Sydney/Faculty of Engineering and Information Technology
pubs.organisational-group	University of Technology Sydney/Faculty of Engineering and Information Technology/School of Electrical and Data Engineering
pubs.organisational-group	University of Technology Sydney/UTS Groups
pubs.organisational-group	University of Technology Sydney/UTS Groups/Centre for Clean Energy Technology (CCET)
pubs.organisational-group	University of Technology Sydney/UTS Groups/Centre for Clean Energy Technology (CCET)/Centre for Clean Energy Technology (CCET) Associate Members
utslib.copyright.status	open_access	*
dc.rights.license	This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0). To view a copy of this license, visit https://creativecommons.org/licenses/by/4.0/
dc.date.updated	2025-08-30T14:33:54Z
pubs.issue	22
pubs.publication-status	Published
pubs.volume	137
utslib.citation.issue	22

Abstract:

Epitaxial graphene on cubic silicon carbide on silicon could enable unique optical metasurface devices seamlessly integrated with CMOS technologies. However, one of the most promising methods to obtain large-scale epitaxial graphene on this challenging system typically leads to a highly p-type-doped graphene with a Fermi level pinned at ∼0.55 eV below the Dirac point. Hence, the use of conventional gate dielectric materials such as SiO2 and Si3N4 precludes the tuning of the graphene carrier concentration. We demonstrate that this limitation can be overcome with the use of polyethyleneimine (PEI) as a gate dielectric material for graphene field-effect transistors. We achieve significant tuning of the graphene's Fermi level, enabling ambipolar operation exceeding a 3 eV window. In addition, we demonstrate that excellent stability of the PEI-based devices can be achieved, thanks to the addition of a thin protective oxide film. These findings highlight the potential of ionic polymers for advancing reconfigurable graphene-based devices for photonic applications.

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http://hdl.handle.net/10453/189529