Gold-mediated exfoliation of MoS2 has recently attracted considerable interest. The strong interaction between MoS2 and Au facilitates preferential production of centimeter-sized monolayer MoS2 with near-unity yield and provides a heterostructure system noteworthy from a fundamental standpoint. However, little is known about the detailed nature of the MoS2-Au interaction and its evolution with the MoS2 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 MoS2. Tip-enhanced Raman spectroscopy reveals heterogeneity of the MoS2-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 MoS2-Au interaction and guide strain and charge doping engineering of MoS2.

Centre for Advanced 2D Materials National University of Singapore 117546 Singapore

Chongqing 2D Materials Institute Liangjiang New Area Chongqing 400714 China

Department of Chemistry and Chemical Biology Cornell University Ithaca New York 14853 United States

Department of Physics and Astronomy University of Manchester Oxford Road Manchester M13 9PL United Kingdom

HORIBA Scientific Novato California 94949 United States

Institute of Physics Czech Academy of Sciences Na Slovance 1999 2 182 21 Prague 8 Czech Republic

J Heyrovský Institute of Physical Chemistry Czech Academy of Sciences Dolejškova 2155 3 182 23 Prague Czech Republic

School of Mathematics and Physics Queen's University Belfast University Road Belfast BT7 1NN United Kingdom

Zobrazit více v PubMed

Magda G. Z.; Pető J.; Dobrik G.; Hwang C.; Biró L. P.; Tapasztó L. Exfoliation of Large-Area Transition Metal Chalcogenide Single Layers. Sci. Rep. 2015, 5, 14714.10.1038/srep14714. PubMed DOI PMC

Desai S. B.; Madhvapathy S. R.; Amani M.; Kiriya D.; Hettick M.; Tosun M.; Zhou Y.; Dubey M.; Ager J. W.; Chrzan D.; et al. Gold-Mediated Exfoliation of Ultralarge Optoelectronically-Perfect Monolayers. Adv. Mater. 2016, 28, 4053–4058. 10.1002/adma.201506171. PubMed DOI

Velický M.; Donnelly G. E.; Hendren W. R.; McFarland S.; Scullion D.; DeBenedetti W. J. I.; Correa G. C.; Han Y.; Wain A. J.; Hines M. A.; et al. Mechanism of Gold-Assisted Exfoliation of Centimeter-Sized Transition-Metal Dichalcogenide Monolayers. ACS Nano 2018, 12, 10463–10472. 10.1021/acsnano.8b06101. PubMed DOI

Guo S.; Yang D.; Li B.; Dong Q.; Li Z.; Zaghloul M. E.. 2019 IEEE 62nd International Midwest Symposium on Circuits and Systems, 4–7 Aug. 2019; pp 884–887.

Gramling H. M.; Towle C. M.; Desai S. B.; Sun H.; Lewis E. C.; Nguyen V. D.; Ager J. W.; Chrzan D.; Yeatman E. M.; Javey A.; et al. Spatially Precise Transfer of Patterned Monolayer WS2 and MoS2 with Features Larger than 104 μm2 Directly from Multilayer Sources. ACS Appl. Electron. Mater. 2019, 1, 407–416. 10.1021/acsaelm.8b00128. DOI

Nguyen V.; Gramling H.; Towle C.; Li W.; Lien D.-H.; Kim H.; Chrzan D. C.; Javey A.; Xu K.; Ager J.; et al. Deterministic Assembly of Arrays of Lithographically Defined WS2 and MoS2 Monolayer Features Directly From Multilayer Sources Into Van Der Waals Heterostructures. J. Micro Nano-Manuf. 2019, 7, 041006.10.1115/1.4045259. DOI

Liu F.; Wu W.; Bai Y.; Chae S. H.; Li Q.; Wang J.; Hone J.; Zhu X.-Y. Disassembling 2D van der Waals crystals into macroscopic monolayers and reassembling into artificial lattices. Science 2020, 367, 903–906. 10.1126/science.aba1416. PubMed DOI

Sun H.; Sirott E. W.; Mastandrea J.; Gramling H. M.; Zhou Y.; Poschmann M.; Taylor H. K.; Ager J. W.; Chrzan D. C. Theory of thin-film-mediated exfoliation of van der Waals bonded layered materials. Phys. Rev. Mater. 2018, 2, 094004.10.1103/PhysRevMaterials.2.094004. DOI

Blue B. T.; Jernigan G. G.; Le D.; Fonseca J. J.; Lough S. D.; Thompson J. E.; Smalley D. D.; Rahman T. S.; Robinson J. T.; Ishigami M. Metallicity of 2H-MoS2 induced by Au hybridization. 2D Mater. 2020, 7, 025021.10.1088/2053-1583/ab6d34. DOI

Donnelly G. E.; Velický M.; Hendren W. R.; Bowman R. M.; Huang F. Achieving extremely high optical contrast of atomically-thin MoS2. Nanotechnology 2020, 31, 145706.10.1088/1361-6528/ab6237. PubMed DOI

Michail A.; Delikoukos N.; Parthenios J.; Galiotis C.; Papagelis K. Optical detection of strain and doping inhomogeneities in single layer MoS2. Appl. Phys. Lett. 2016, 108, 173102.10.1063/1.4948357. DOI

Lloyd D.; Liu X.; Christopher J. W.; Cantley L.; Wadehra A.; Kim B. L.; Goldberg B. B.; Swan A. K.; Bunch J. S. Band Gap Engineering with Ultralarge Biaxial Strains in Suspended Monolayer MoS2. Nano Lett. 2016, 16, 5836–5841. 10.1021/acs.nanolett.6b02615. PubMed DOI

Pető J.; Dobrik G.; Kukucska G.; Vancsó P.; Koós A. A.; Koltai J.; Nemes-Incze P.; Hwang C.; Tapasztó L. Moderate strain induced indirect bandgap and conduction electrons in MoS2 single layers. npj 2D Mater. Appl. 2019, 3, 39.10.1038/s41699-019-0123-5. DOI

Chakraborty B.; Bera A.; Muthu D. V. S.; Bhowmick S.; Waghmare U. V.; Sood A. K. Symmetry-dependent phonon renormalization in monolayer MoS2 transistor. Phys. Rev. B: Condens. Matter Mater. Phys. 2012, 85, 161403.10.1103/PhysRevB.85.161403. DOI

Melnikova-Kominkova Z.; Jurkova K.; Vales V.; Drogowska-Horná K.; Frank O.; Kalbac M. Strong and efficient doping of monolayer MoS2 by a graphene electrode. Phys. Chem. Chem. Phys. 2019, 21, 25700–25706. 10.1039/C9CP04993B. PubMed DOI

Gong C.; Huang C.; Miller J.; Cheng L.; Hao Y.; Cobden D.; Kim J.; Ruoff R. S.; Wallace R. M.; Cho K.; et al. Metal Contacts on Physical Vapor Deposited Monolayer MoS2. ACS Nano 2013, 7, 11350–11357. 10.1021/nn4052138. PubMed DOI

Sørensen S. G.; Füchtbauer H. G.; Tuxen A. K.; Walton A. S.; Lauritsen J. V. Structure and Electronic Properties of In Situ Synthesized Single-Layer MoS2 on a Gold Surface. ACS Nano 2014, 8, 6788–6796. 10.1021/nn502812n. PubMed DOI

Sohier T.; Ponomarev E.; Gibertini M.; Berger H.; Marzari N.; Ubrig N.; Morpurgo A. F. Enhanced Electron-Phonon Interaction in Multivalley Materials. Phys. Rev. X 2019, 9, 031019.10.1103/PhysRevX.9.031019. DOI

Scheuschner N.; Ochedowski O.; Kaulitz A.-M.; Gillen R.; Schleberger M.; Maultzsch J. Photoluminescence of freestanding single- and few-layer MoS2. Phys. Rev. B: Condens. Matter Mater. Phys. 2014, 89, 125406.10.1103/PhysRevB.89.125406. DOI

Rodriguez A.; Verhagen T.; Kalbac M.; Vejpravova J.; Frank O. Imaging Nanoscale Inhomogeneities and Edge Delamination in As-Grown MoS2 Using Tip-Enhanced Photoluminescence. Phys. Status Solidi RRL 2019, 13, 1900381.10.1002/pssr.201900381. DOI

Konečný M.; Bartošík M.; Mach J.; Švarc V.; Nezval D.; Piastek J.; Procházka P.; Cahlík A.; Šikola T. Kelvin Probe Force Microscopy and Calculation of Charge Transport in a Graphene/Silicon Dioxide System at Different Relative Humidity. ACS Appl. Mater. Interfaces 2018, 10, 11987–11994. 10.1021/acsami.7b18041. PubMed DOI

Pimenta M. A.; del Corro E.; Carvalho B. R.; Fantini C.; Malard L. M. Comparative Study of Raman Spectroscopy in Graphene and MoS2-type Transition Metal Dichalcogenides. Acc. Chem. Res. 2015, 48, 41–47. 10.1021/ar500280m. PubMed DOI

Li H.; Contryman A. W.; Qian X.; Ardakani S. M.; Gong Y.; Wang X.; Weisse J. M.; Lee C. H.; Zhao J.; Ajayan P. M.; et al. Optoelectronic crystal of artificial atoms in strain-textured molybdenum disulphide. Nat. Commun. 2015, 6, 7381.10.1038/ncomms8381. PubMed DOI PMC

Rice C.; Young R. J.; Zan R.; Bangert U.; Wolverson D.; Georgiou T.; Jalil R.; Novoselov K. S. Raman-scattering measurements and first-principles calculations of strain-induced phonon shifts in monolayer MoS2. Phys. Rev. B: Condens. Matter Mater. Phys. 2013, 87, 081307.10.1103/PhysRevB.87.081307. DOI

Trainer D. J.; Zhang Y.; Bobba F.; Xi X.; Hla S.-W.; Iavarone M. The Effects of Atomic-Scale Strain Relaxation on the Electronic Properties of Monolayer MoS2. ACS Nano 2019, 13, 8284–8291. 10.1021/acsnano.9b03652. PubMed DOI

Yasuda S.; Takahashi R.; Osaka R.; Kumagai R.; Miyata Y.; Okada S.; Hayamizu Y.; Murakoshi K. Out-of-Plane Strain Induced in a Moiré Superstructure of Monolayer MoS2 and MoSe2 on Au(111). Small 2017, 13, 1700748.10.1002/smll.201700748. PubMed DOI

Bruix A.; Füchtbauer H. G.; Tuxen A. K.; Walton A. S.; Andersen M.; Porsgaard S.; Besenbacher F.; Hammer B.; Lauritsen J. V. In Situ Detection of Active Edge Sites in Single-Layer MoS2 Catalysts. ACS Nano 2015, 9, 9322–9330. 10.1021/acsnano.5b03199. PubMed DOI

Mattila S.; Leiro J. A.; Heinonen M.; Laiho T. Core level spectroscopy of MoS2. Surf. Sci. 2006, 600, 5168–5175. 10.1016/j.susc.2006.08.038. DOI

Yu Y.; Nam G.-H.; He Q.; Wu X.-J.; Zhang K.; Yang Z.; Chen J.; Ma Q.; Zhao M.; Liu Z.; et al. High phase-purity 1T′-MoS2- and 1T′-MoSe2-layered crystals. Nat. Chem. 2018, 10, 638–643. 10.1038/s41557-018-0035-6. PubMed DOI

Yin X.; Wang Q.; Cao L.; Tang C. S.; Luo X.; Zheng Y.; Wong L. M.; Wang S. J.; Quek S. Y.; Zhang W.; et al. Tunable inverted gap in monolayer quasi-metallic MoS2 induced by strong charge-lattice coupling. Nat. Commun. 2017, 8, 486.10.1038/s41467-017-00640-2. PubMed DOI PMC

Peña-Álvarez M.; del Corro E.; Morales-García Á.; Kavan L.; Kalbac M.; Frank O. Single Layer Molybdenum Disulfide under Direct Out-of-Plane Compression: Low-Stress Band-Gap Engineering. Nano Lett. 2015, 15, 3139–3146. 10.1021/acs.nanolett.5b00229. PubMed DOI

Lee C.; Yan H.; Brus L. E.; Heinz T. F.; Hone J.; Ryu S. Anomalous Lattice Vibrations of Single- and Few-Layer MoS2. ACS Nano 2010, 4, 2695–2700. 10.1021/nn1003937. PubMed DOI

Zhang X.; Qiao X.-F.; Shi W.; Wu J.-B.; Jiang D.-S.; Tan P.-H. Phonon and Raman scattering of two-dimensional transition metal dichalcogenides from monolayer, multilayer to bulk material. Chem. Soc. Rev. 2015, 44, 2757–2785. 10.1039/C4CS00282B. PubMed DOI

Scheuschner N.; Gillen R.; Staiger M.; Maultzsch J. Interlayer resonant Raman modes in few-layer MoS2. Phys. Rev. B: Condens. Matter Mater. Phys. 2015, 91, 235409.10.1103/PhysRevB.91.235409. DOI

Hybridization Directionality Governs the Interaction Strength between MoS2 and Metals

Strain-Induced Decoupling Drives Gold-Assisted Exfoliation of Large-Area Monolayer 2D Crystals