Layer-dependent Schottky contact at van der Waals interfaces: V-doped WSe2 on graphene

Samuel Stolz; Azimkhan Kozhakhmetov; Chengye Dong; Oliver Gröning; Joshua A. Robinson; Bruno Schuler

doi:10.1038/s41699-022-00342-4

Layer-dependent Schottky contact at van der Waals interfaces: V-doped WSe₂ on graphene

Samuel Stolz, Azimkhan Kozhakhmetov, Chengye Dong, Oliver Gröning, Joshua A. Robinson, Bruno Schuler

Research output: Contribution to journal › Article › peer-review

15 Scopus citations

Abstract

Contacting two-dimensional (2D) semiconductors with van der Waals semimetals significantly reduces the contact resistance and Fermi level pinning due to defect-free interfaces. However, depending on the band alignment, a Schottky barrier remains. Here we study the evolution of the valence and conduction band edges in pristine and heavily vanadium (0.44%), i.e., p-type, doped epitaxial WSe₂ on quasi-freestanding graphene (QFEG) on silicon carbide as a function of thickness. We find that with increasing number of layers the Fermi level of the doped WSe₂ gets pinned at the highest dopant level for three or more monolayers. This implies a charge depletion region of about 1.6 nm. Consequently, V dopants in the first and second WSe₂ layer on QFEG/SiC are ionized (negatively charged) whereas they are charge neutral beyond the second layer.

Original language	English (US)
Article number	66
Journal	npj 2D Materials and Applications
Volume	6
Issue number	1
DOIs	https://doi.org/10.1038/s41699-022-00342-4
State	Published - Dec 2022

All Science Journal Classification (ASJC) codes

General Chemistry
General Materials Science
Condensed Matter Physics
Mechanics of Materials
Mechanical Engineering

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title = "Layer-dependent Schottky contact at van der Waals interfaces: V-doped WSe2 on graphene",

abstract = "Contacting two-dimensional (2D) semiconductors with van der Waals semimetals significantly reduces the contact resistance and Fermi level pinning due to defect-free interfaces. However, depending on the band alignment, a Schottky barrier remains. Here we study the evolution of the valence and conduction band edges in pristine and heavily vanadium (0.44%), i.e., p-type, doped epitaxial WSe2 on quasi-freestanding graphene (QFEG) on silicon carbide as a function of thickness. We find that with increasing number of layers the Fermi level of the doped WSe2 gets pinned at the highest dopant level for three or more monolayers. This implies a charge depletion region of about 1.6 nm. Consequently, V dopants in the first and second WSe2 layer on QFEG/SiC are ionized (negatively charged) whereas they are charge neutral beyond the second layer.",

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T2 - V-doped WSe2 on graphene

AU - Stolz, Samuel

AU - Kozhakhmetov, Azimkhan

AU - Dong, Chengye

AU - Gröning, Oliver

AU - Robinson, Joshua A.

AU - Schuler, Bruno

PY - 2022/12

Y1 - 2022/12

N2 - Contacting two-dimensional (2D) semiconductors with van der Waals semimetals significantly reduces the contact resistance and Fermi level pinning due to defect-free interfaces. However, depending on the band alignment, a Schottky barrier remains. Here we study the evolution of the valence and conduction band edges in pristine and heavily vanadium (0.44%), i.e., p-type, doped epitaxial WSe2 on quasi-freestanding graphene (QFEG) on silicon carbide as a function of thickness. We find that with increasing number of layers the Fermi level of the doped WSe2 gets pinned at the highest dopant level for three or more monolayers. This implies a charge depletion region of about 1.6 nm. Consequently, V dopants in the first and second WSe2 layer on QFEG/SiC are ionized (negatively charged) whereas they are charge neutral beyond the second layer.

AB - Contacting two-dimensional (2D) semiconductors with van der Waals semimetals significantly reduces the contact resistance and Fermi level pinning due to defect-free interfaces. However, depending on the band alignment, a Schottky barrier remains. Here we study the evolution of the valence and conduction band edges in pristine and heavily vanadium (0.44%), i.e., p-type, doped epitaxial WSe2 on quasi-freestanding graphene (QFEG) on silicon carbide as a function of thickness. We find that with increasing number of layers the Fermi level of the doped WSe2 gets pinned at the highest dopant level for three or more monolayers. This implies a charge depletion region of about 1.6 nm. Consequently, V dopants in the first and second WSe2 layer on QFEG/SiC are ionized (negatively charged) whereas they are charge neutral beyond the second layer.

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Layer-dependent Schottky contact at van der Waals interfaces: V-doped WSe₂ on graphene

Abstract

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