Strong and efficient doping of monolayer MoS<sub>2</sub> by a graphene electrode

Melníková-Komínková, Zuzana; Jurkova, Katerina; Valeš, Václav; Drogowska-Horná, Karolina; Frank, Otakar; Kalbáč, Martin

doi:10.1039/c9cp04993b

Cited by 22 publications

(39 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For purposes of the substrate comparison, we disregard the possible effects of charge doping, which causes E′ mode shifts smaller than 1 cm –1 for the charge carrier density up to nearly 10 14 cm –2 . [ 15 ] The strain median, which was chosen to capture the mean values of the diverse E′ mode shapes in Figure 3a, increases from 0.7% on Pd, to 1.3% on Pt, 1.4% on Ag, and 1.5% on Au. The E′ mode on Au is nearly symmetric and fittable with a single Voigt line shape but broader than on SiO 2 (cf.…”

Section: Figurementioning

confidence: 99%

The Intricate Love Affairs between MoS₂ and Metallic Substrates

Velický

Donnelly

Hendren

et al. 2020

Adv Materials Inter

Self Cite

View full text Add to dashboard Cite

Mechanical exfoliation of 2D materials yields high-quality crystals popular with researchers in fundamental scientific disciplines but its scalability is severely limited. This method generates 2D monolayers tens or hundreds of microns in lateral sizes on most substrates, often after an elaborate surface treatment. [1] Gold-mediated exfoliation of chalcogenides, chlorides, thiophosphates, black phosphorus, and black arsenic, with a robust control of the near-unity monolayer yield at a millimeter-/centimeterscale, has recently emerged as a viable solution to the scalability issues, [2] and has been adopted in various branches of applied research and engineering. [3] In the case of transition metal dichalcogenides (TMDCs), the root of the preferential mono layer exfoliation has been attributed to the strong interactions between gold and chalcogenides, which have been explored in different facets of science for decades. [4] However, it has recently been shown that the interaction between TMDCs and Au is non-covalent and van der Waals (vdW) in its nature, inferred from the sizeable S-Au equilibrium distance (3.5 Å) and binding energies in the Au-MoS 2 heterostructure. [2c,5] The vdW interaction therefore facilitates the transfer of the TMDC monolayers onto non-metallic substrates, which restore their semiconducting characteristics exploitable in optoelectronics, photovoltaics, and related themes. [2b] The polymer-free nature of this transfer, which leaves surfaces free from residual contamination, is of significant advantage also. [6] Despite these research efforts, it is currently unknown whether this method can also be applied to other metals, predicted to exhibit even stronger binding with MoS 2 than Au. [7] Here, we study the ability of different metallic substrates to exfoliate large-area monolayer MoS 2. We find that gold is by far the best substrate, outperforming all other metals by at least two orders of magnitude in terms of the lateral size of the MoS 2 , thanks to the unique ability of Au to resist oxidation and the sizeable interfacial strain in the Au-MoS 2 heterostructure. A moderate exfoliation yield is achieved for other precious metals, including Pt, Pd, and Ag, while hardly any exfoliated material is found on base metals, including Cu, Ni, Co, Cr, and Ti, which suffer from significant oxidation of their surface upon exposure to air. A correlation between the maximum lateral Mechanical exfoliation yields high-quality 2D materials but is challenging to scale up due to the small lateral size and low yield of the exfoliated crystals. Gold-mediated exfoliation of macroscale monolayer MoS 2 and related crystals addresses this problem. However, it remains unclear whether this method can be extended to other metals. Herein, mechanical exfoliation of MoS 2 on a range of metallic substrates is studied. It is found that Au outperforms all the other metals in their ability to exfoliate macroscale monolayer MoS 2. This is rationalized by gold's ability to resist oxidation, which is compromised on other metals a...

show abstract

Section: Figurementioning

confidence: 99%

The Intricate Love Affairs between MoS₂ and Metallic Substrates

Velický

Donnelly

Hendren

et al. 2020

Adv Materials Inter

Self Cite

View full text Add to dashboard Cite

show abstract

“…The observed strain and doping are among the highest observed to date. 9 , 12 , 14 , 15 , 18 , 23 − 25 Several previous studies of the MoS 2 /Au heterostructure report the Raman spectra. Upshifts of both the E′/E 2g 1 and A 1 ′/A 1g modes with the MoS 2 thickness were observed using a low-resolution spectrometer, 3 , 10 consistent with Figure 1 c if heavily averaged spectra are considered.…”

mentioning

confidence: 99%

“…The n-doping of 1L MoS 2 in contact with Au, proven by XPS, UPS, and KPFM, corroborates that it is the increased electron concentration which is responsible for the A 1 ′(L) downshift, in line with electrochemically gated MoS 2 experiments. 14 , 15 , 18 Nevertheless, one could envisage alternative explanations. The strong binding in MoS 2 –Au heterostructures with a clean interface could cause softening of the Mo–S bonds, 26 instead of the stiffening seen for the contaminated MoS 2 –Au interface.…”

mentioning

confidence: 99%

Strain and Charge Doping Fingerprints of the Strong Interaction between Monolayer MoS₂ and Gold

Velický

Rodríguez

Bouša

et al. 2020

J. Phys. Chem. Lett.

Self Cite

147

View full text Add to dashboard Cite

Gold-mediated exfoliation of MoS 2 has recently attracted considerable interest. The strong interaction between MoS 2 and Au facilitates preferential production of centimeter-sized monolayer MoS 2 with near-unity yield and provides a heterostructure system noteworthy from a fundamental standpoint. However, little is known about the detailed nature of the MoS 2 –Au interaction and its evolution with the MoS 2 thickness. Here, we identify the specific vibrational and binding energy fingerprints of this interaction using Raman and X-ray photoelectron spectroscopy, which indicate substantial strain and charge doping in monolayer MoS 2 . Tip-enhanced Raman spectroscopy reveals heterogeneity of the MoS 2 –Au interaction at the nanoscale, reflecting the spatial nonconformity between the two materials. Micro-Raman spectroscopy shows that this interaction is strongly affected by the roughness and cleanliness of the underlying Au. Our results elucidate the nature of the MoS 2 –Au interaction and guide strain and charge doping engineering of MoS 2 .

show abstract

“…[4] Similar doping techniques have been applied to control the charge state in atomically thin materials; in particular, to tune the zero-phonon line in hexagonal boron nitride (hBN), [5] to electrically drive singlephoton emission in tungsten diselenide (WSe 2 ) and tungsten graphene electrodes and ionic liquids at room temperature. [24,25] The ionic liquid-gated field-effect transistors based on TMD monolayers have also enabled the quantitative study of their electronic properties. [26,27] Electrical control of quantum emission is especially interesting for applications that require coupling of excitonic materials with photonic and plasmonic integrated devices.…”

Section: Introductionmentioning

confidence: 99%

“…[ 23 ] Finally, the electrochemical doping approach provides great reversibility and high doping densities of n ≈ 10 14 cm −2 at low voltages of 1–2 V, as it has been demonstrated in experiments on WSe 2 and molybdenum disulfide (MoS 2 ) monolayers using graphene electrodes and ionic liquids at room temperature. [ 24,25 ] The ionic liquid‐gated field‐effect transistors based on TMD monolayers have also enabled the quantitative study of their electronic properties. [ 26,27 ]…”

Section: Introductionmentioning

confidence: 99%

Room‐Temperature Low‐Voltage Control of Excitonic Emission in Transition Metal Dichalcogenide Monolayers

Морозов

Wolff

Mortensen

2021

Advanced Optical Materials

View full text Add to dashboard Cite

Charge doping of materials with 2D and 3D quantum confinement is a flexible tool to tailor their excitonic emission. Here, using electron doping experiments on transition metal dichalcogenide (TMD) monolayers, reversible tuning of charged exciton emission within a redshift of up to 75 meV is demonstrated by applying very modest voltages (corresponding roughly to the band gap of TMDs), while also controlling the radiative lifetime and intensity. It is found that the neutral exciton ionization dynamics at increasing electron doping follows the Fermi–Dirac distribution, which allows to determine the size of the band gap as well as to extract experimental values for effective masses of electrons and holes at room temperature. The tunable excitonic emission, preserving coherence at room temperature, holds great promise for quantum technologies requiring deterministic coupling with integrated photonic and plasmonic devices.

show abstract

Strong and efficient doping of monolayer MoS₂ by a graphene electrode

Abstract: Monolayer MoS2 is efficiently doped in a complete electrochemical setup using graphene simultaneously as the electrode and protective spacer.

Cited by 22 publications

References 45 publications

The Intricate Love Affairs between MoS₂ and Metallic Substrates

The Intricate Love Affairs between MoS₂ and Metallic Substrates

Strain and Charge Doping Fingerprints of the Strong Interaction between Monolayer MoS₂ and Gold

Room‐Temperature Low‐Voltage Control of Excitonic Emission in Transition Metal Dichalcogenide Monolayers

Contact Info

Product

Resources

About

Strong and efficient doping of monolayer MoS2 by a graphene electrode

Abstract: Monolayer MoS2 is efficiently doped in a complete electrochemical setup using graphene simultaneously as the electrode and protective spacer.

Cited by 22 publications

References 45 publications

The Intricate Love Affairs between MoS2 and Metallic Substrates

The Intricate Love Affairs between MoS2 and Metallic Substrates

Strain and Charge Doping Fingerprints of the Strong Interaction between Monolayer MoS2 and Gold

Room‐Temperature Low‐Voltage Control of Excitonic Emission in Transition Metal Dichalcogenide Monolayers

Contact Info

Product

Resources

About

Strong and efficient doping of monolayer MoS₂ by a graphene electrode

The Intricate Love Affairs between MoS₂ and Metallic Substrates

The Intricate Love Affairs between MoS₂ and Metallic Substrates

Strain and Charge Doping Fingerprints of the Strong Interaction between Monolayer MoS₂ and Gold