Basal plane oxygen exchange of epitaxial MoS2 without edge oxidation

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Basal plane oxygen exchange of epitaxial MoS2 without edge oxidation. / Gronborg, Signe S.; Thorarinsdottir, Kristbjörg; Kyhl, Line; Rodriguez-Fernández, Jonathan; Sanders, Charlotte E.; Bianchi, Marco; Hofmann, Philip; Miwa, Jill A.; Ulstrup, Soren; Lauritsen, Jeppe V.

In: 2D materials, Vol. 6, No. 4, 045013, 10.2019.

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Gronborg SS, Thorarinsdottir K, Kyhl L, Rodriguez-Fernández J, Sanders CE, Bianchi M et al. Basal plane oxygen exchange of epitaxial MoS2 without edge oxidation. 2D materials. 2019 Oct;6(4). 045013. https://doi.org/10.1088/2053-1583/ab2d00

Author

Gronborg, Signe S. ; Thorarinsdottir, Kristbjörg ; Kyhl, Line ; Rodriguez-Fernández, Jonathan ; Sanders, Charlotte E. ; Bianchi, Marco ; Hofmann, Philip ; Miwa, Jill A. ; Ulstrup, Soren ; Lauritsen, Jeppe V. / Basal plane oxygen exchange of epitaxial MoS2 without edge oxidation. In: 2D materials. 2019 ; Vol. 6, No. 4.

Bibtex

@article{30d157796b964f5ca6a406af35b30673,
title = "Basal plane oxygen exchange of epitaxial MoS2 without edge oxidation",
abstract = "The intentional formation of defects in transition-metal dichalcogenides, such as MoS2, is an attractive way to modify the electronic and chemical properties of this class of 2D materials. However, the mechanisms and methods available for selective doping or modification of the basal plane must be improved. Here we investigate the process of O defect formation in epitaxial single-layer MoS2 on Au(1 1 1) using scanning tunneling microscopy (STM) and ambient pressure x-ray photoelectron spectroscopy (AP-XPS) during oxidation with O2 and H2O gas from low vacuum to the mbar range. Both oxidants result in exchange of S in the upper part of the basal plane with O, in line with air exposure experiments. Temperature-dependent measurements show that this is an activated process with an experimentally estimated reaction barrier of ∼0.79 ± 0.20 eV. We surprisingly find that the morphology of the MoS2 flakes and their edges remain intact in O2, even for relatively high degrees of basal plane O exchange, in contrast to the oxidation behavior of exfoliated single-layer MoS2. From analysis of atom-resolved STM images of the MoS2 edges, we can attribute this unusual stability to a passivating effect of excess edge sulfur species adsorbed under the sulfiding conditions of the MoS2 synthesis in H2S gas. We thus demonstrate that control over pre-sulfidation of the edges, temperature and pressure during oxidation can be used in a fast process to form strongly O doped single-layer MoS2 with no degradation of the initial shape and edge structure of the epitaxial MoS2 sheet.",
keywords = "ambient pressure x-ray photoelectron spectroscopy, defect engineering in 2D materials, monolayer MoS, MoS edges, O defects, scanning tunneling microscopy",
author = "Gronborg, {Signe S.} and Kristbj{\"o}rg Thorarinsdottir and Line Kyhl and Jonathan Rodriguez-Fern{\'a}ndez and Sanders, {Charlotte E.} and Marco Bianchi and Philip Hofmann and Miwa, {Jill A.} and Soren Ulstrup and Lauritsen, {Jeppe V.}",
year = "2019",
month = oct,
doi = "10.1088/2053-1583/ab2d00",
language = "English",
volume = "6",
journal = "2D materials",
issn = "2053-1583",
publisher = "IOP Publishing",
number = "4",

}

RIS

TY - JOUR

T1 - Basal plane oxygen exchange of epitaxial MoS2 without edge oxidation

AU - Gronborg, Signe S.

AU - Thorarinsdottir, Kristbjörg

AU - Kyhl, Line

AU - Rodriguez-Fernández, Jonathan

AU - Sanders, Charlotte E.

AU - Bianchi, Marco

AU - Hofmann, Philip

AU - Miwa, Jill A.

AU - Ulstrup, Soren

AU - Lauritsen, Jeppe V.

PY - 2019/10

Y1 - 2019/10

N2 - The intentional formation of defects in transition-metal dichalcogenides, such as MoS2, is an attractive way to modify the electronic and chemical properties of this class of 2D materials. However, the mechanisms and methods available for selective doping or modification of the basal plane must be improved. Here we investigate the process of O defect formation in epitaxial single-layer MoS2 on Au(1 1 1) using scanning tunneling microscopy (STM) and ambient pressure x-ray photoelectron spectroscopy (AP-XPS) during oxidation with O2 and H2O gas from low vacuum to the mbar range. Both oxidants result in exchange of S in the upper part of the basal plane with O, in line with air exposure experiments. Temperature-dependent measurements show that this is an activated process with an experimentally estimated reaction barrier of ∼0.79 ± 0.20 eV. We surprisingly find that the morphology of the MoS2 flakes and their edges remain intact in O2, even for relatively high degrees of basal plane O exchange, in contrast to the oxidation behavior of exfoliated single-layer MoS2. From analysis of atom-resolved STM images of the MoS2 edges, we can attribute this unusual stability to a passivating effect of excess edge sulfur species adsorbed under the sulfiding conditions of the MoS2 synthesis in H2S gas. We thus demonstrate that control over pre-sulfidation of the edges, temperature and pressure during oxidation can be used in a fast process to form strongly O doped single-layer MoS2 with no degradation of the initial shape and edge structure of the epitaxial MoS2 sheet.

AB - The intentional formation of defects in transition-metal dichalcogenides, such as MoS2, is an attractive way to modify the electronic and chemical properties of this class of 2D materials. However, the mechanisms and methods available for selective doping or modification of the basal plane must be improved. Here we investigate the process of O defect formation in epitaxial single-layer MoS2 on Au(1 1 1) using scanning tunneling microscopy (STM) and ambient pressure x-ray photoelectron spectroscopy (AP-XPS) during oxidation with O2 and H2O gas from low vacuum to the mbar range. Both oxidants result in exchange of S in the upper part of the basal plane with O, in line with air exposure experiments. Temperature-dependent measurements show that this is an activated process with an experimentally estimated reaction barrier of ∼0.79 ± 0.20 eV. We surprisingly find that the morphology of the MoS2 flakes and their edges remain intact in O2, even for relatively high degrees of basal plane O exchange, in contrast to the oxidation behavior of exfoliated single-layer MoS2. From analysis of atom-resolved STM images of the MoS2 edges, we can attribute this unusual stability to a passivating effect of excess edge sulfur species adsorbed under the sulfiding conditions of the MoS2 synthesis in H2S gas. We thus demonstrate that control over pre-sulfidation of the edges, temperature and pressure during oxidation can be used in a fast process to form strongly O doped single-layer MoS2 with no degradation of the initial shape and edge structure of the epitaxial MoS2 sheet.

KW - ambient pressure x-ray photoelectron spectroscopy

KW - defect engineering in 2D materials

KW - monolayer MoS

KW - MoS edges

KW - O defects

KW - scanning tunneling microscopy

UR - http://www.scopus.com/inward/record.url?scp=85071138618&partnerID=8YFLogxK

U2 - 10.1088/2053-1583/ab2d00

DO - 10.1088/2053-1583/ab2d00

M3 - Journal article

AN - SCOPUS:85071138618

VL - 6

JO - 2D materials

JF - 2D materials

SN - 2053-1583

IS - 4

M1 - 045013

ER -