High mobility is a crucial requirement for a large variety of electronic device applications. The state of the art for high-quality graphene devices is based on heterostructures made with graphene encapsulated in nm-thick flakes of hexagonal boron nitride (hBN). Unfortunately, scaling up multilayer hBN while precisely controlling the number of layers remains an outstanding challenge, resulting in a rough material unable to enhance the mobility of graphene. This leads to the pursuit of alternative, scalable materials, which can be used as substrates and encapsulants for graphene. Tungsten disulfide (WS2) is a transition metal dichalcogenide, which was grown in large (∼mm-size) multi-layers by chemical vapor deposition. However, the resistance vs gate voltage characteristics when gating graphene through WS2 exhibit largely hysteretic shifts of the charge neutrality point on the order of 3 × 1011 cm−2, hindering the use of WS2 as a reliable encapsulant. The hysteresis originates due to the charge traps from sulfur vacancies present in WS2. In this work, we report the use of WS2 as a substrate and overcome the hysteresis issues by chemically treating WS2 with a super-acid, which passivates these vacancies and strips the surface from contaminants. The hysteresis is significantly reduced by about two orders of magnitude, down to values as low as 2 × 109 cm−2, while the room-temperature mobility of WS2-encapsulated graphene is as high as ∼62 × 103 cm2 V−1 s−1 at a carrier density of n ∼ 1 cm−2. Our results promote WS2 as a valid alternative to hBN as an encapsulant for high-performance graphene devices.
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7 August 2023
Research Article|
August 08 2023
Hysteresis-free high mobility graphene encapsulated in tungsten disulfide
Special Collection:
Critical Issues on the 2D-material-based field-effect transistors
Karuppasamy Pandian Soundarapandian
;
Karuppasamy Pandian Soundarapandian
(Conceptualization, Data curation, Investigation, Methodology, Visualization, Writing – original draft, Writing – review & editing)
1
ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology
, 08860 Castelldefels, Barcelona, Spain
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Domenico De Fazio
;
Domenico De Fazio
a)
(Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Resources, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing)
1
ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology
, 08860 Castelldefels, Barcelona, Spain
2
Department of Molecular Sciences and Nanosystems, Ca-Foscari University of Venice
, 30172 Venezia, Veneto, Italy
a)Authors to whom correspondence should be addressed: domenico.defazio@unive.it and frank.koppens@icfo.eu
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Francisco Bernal-Texca
;
Francisco Bernal-Texca
(Data curation, Formal analysis, Investigation, Methodology, Software, Validation)
1
ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology
, 08860 Castelldefels, Barcelona, Spain
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Rebecca Hoffmann
;
Rebecca Hoffmann
(Data curation, Investigation, Methodology, Software, Validation)
1
ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology
, 08860 Castelldefels, Barcelona, Spain
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Matteo Ceccanti
;
Matteo Ceccanti
(Data curation, Formal analysis, Investigation, Methodology, Visualization)
1
ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology
, 08860 Castelldefels, Barcelona, Spain
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Sergio L. De Bonis
;
Sergio L. De Bonis
(Data curation, Formal analysis, Investigation, Validation, Visualization)
1
ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology
, 08860 Castelldefels, Barcelona, Spain
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Sefaattin Tongay
;
Sefaattin Tongay
(Funding acquisition, Resources, Writing – original draft, Writing – review & editing)
3
School for Engineering of Matter, Transport and Energy, Arizona State University
, Tempe, Arizona 85287, USA
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Frank H. L. Koppens
Frank H. L. Koppens
a)
(Formal analysis, Funding acquisition, Project administration, Resources, Supervision, Writing – original draft, Writing – review & editing)
1
ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology
, 08860 Castelldefels, Barcelona, Spain
4
ICREA – Institució Catalana de Recerça i Estudis Avancats
, 08010 Barcelona, Spain
a)Authors to whom correspondence should be addressed: domenico.defazio@unive.it and frank.koppens@icfo.eu
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a)Authors to whom correspondence should be addressed: domenico.defazio@unive.it and frank.koppens@icfo.eu
Appl. Phys. Lett. 123, 063103 (2023)
Article history
Received:
March 20 2023
Accepted:
July 20 2023
Citation
Karuppasamy Pandian Soundarapandian, Domenico De Fazio, Francisco Bernal-Texca, Rebecca Hoffmann, Matteo Ceccanti, Sergio L. De Bonis, Sefaattin Tongay, Frank H. L. Koppens; Hysteresis-free high mobility graphene encapsulated in tungsten disulfide. Appl. Phys. Lett. 7 August 2023; 123 (6): 063103. https://doi.org/10.1063/5.0151273
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