WSe2 homojunctions and quantum dots created by patterned hydrogenation of epitaxial graphene substrates

Yi Pan, Stefan Fölsch, Yu Chuan Lin, Bhakti Jariwala, Joshua A. Robinson, Yifan Nie, Kyeongjae Cho, Randall M. Feenstra

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Scanning tunneling microscopy (STM) at 5 K is used to study WSe2 layers grown on epitaxial graphene which is formed on Si-terminated SiC(0 0 0 1). Specifically, a partial hydrogenation process is applied to intercalate hydrogen at the SiC-graphene interface, yielding areas of quasi-free-standing bilayer graphene coexisting with bare monolayer graphene. We find that an abrupt and structurally perfect homojunction (band-edge offset ∼0.25 eV) is formed when WSe2 overgrows a lateral junction between adjacent monolayer and quasi-free-standing bilayer areas in the graphene. The band structure modulation in the WSe2 overlayer arises from the varying work function (electrostatic potential) of the graphene beneath. Scanning tunneling spectroscopy measurements reveal that this effect can be also utilized to create WSe2 quantum dots that confine either valence or conduction band states, in agreement with first-principles band structure calculations.

Original languageEnglish (US)
Article number021001
Journal2D Materials
Volume6
Issue number2
DOIs
StatePublished - Jan 17 2019

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homojunctions
Graphite
Graphene
Semiconductor quantum dots
Hydrogenation
hydrogenation
graphene
quantum dots
Substrates
Band structure
Monolayers
Scanning tunneling microscopy
Valence bands
Conduction bands
scanning tunneling microscopy
Hydrogen
Electrostatics
conduction bands
Modulation
Spectroscopy

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

Cite this

Pan, Yi ; Fölsch, Stefan ; Lin, Yu Chuan ; Jariwala, Bhakti ; Robinson, Joshua A. ; Nie, Yifan ; Cho, Kyeongjae ; Feenstra, Randall M. / WSe2 homojunctions and quantum dots created by patterned hydrogenation of epitaxial graphene substrates. In: 2D Materials. 2019 ; Vol. 6, No. 2.
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WSe2 homojunctions and quantum dots created by patterned hydrogenation of epitaxial graphene substrates. / Pan, Yi; Fölsch, Stefan; Lin, Yu Chuan; Jariwala, Bhakti; Robinson, Joshua A.; Nie, Yifan; Cho, Kyeongjae; Feenstra, Randall M.

In: 2D Materials, Vol. 6, No. 2, 021001, 17.01.2019.

Research output: Contribution to journalArticle

TY - JOUR

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AU - Pan, Yi

AU - Fölsch, Stefan

AU - Lin, Yu Chuan

AU - Jariwala, Bhakti

AU - Robinson, Joshua A.

AU - Nie, Yifan

AU - Cho, Kyeongjae

AU - Feenstra, Randall M.

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N2 - Scanning tunneling microscopy (STM) at 5 K is used to study WSe2 layers grown on epitaxial graphene which is formed on Si-terminated SiC(0 0 0 1). Specifically, a partial hydrogenation process is applied to intercalate hydrogen at the SiC-graphene interface, yielding areas of quasi-free-standing bilayer graphene coexisting with bare monolayer graphene. We find that an abrupt and structurally perfect homojunction (band-edge offset ∼0.25 eV) is formed when WSe2 overgrows a lateral junction between adjacent monolayer and quasi-free-standing bilayer areas in the graphene. The band structure modulation in the WSe2 overlayer arises from the varying work function (electrostatic potential) of the graphene beneath. Scanning tunneling spectroscopy measurements reveal that this effect can be also utilized to create WSe2 quantum dots that confine either valence or conduction band states, in agreement with first-principles band structure calculations.

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