- Physical Review Journals
All JournalsPhysics Magazine

Physical Review B

Reuse & Permissions

It is not necessary to obtain permission to reuse this article or its components as it is available under the terms of the Creative Commons Attribution 4.0 International license. This license permits unrestricted use, distribution, and reproduction in any medium, provided attribution to the author(s) and the published article's title, journal citation, and DOI are maintained. Please note that some figures may have been included with permission from other third parties. It is your responsibility to obtain the proper permission from the rights holder directly for these figures.

Export citation

Export citation

Choose format for download:

Download Citation
  • Open Access

Vibration-assisted tunneling through single Au adatoms on two-dimensional WSe2

Hitesh Kumar1, Yu-Chuan Lin2,*, Joshua A. Robinson2, and Stefan Fölsch1,†

  • *Present address: Department of Materials Science and Engineering, National Yang Ming Chiao Tung University, Hsinchu City 300093, Taiwan.
  • †Contact author: foelsch@pdi-berlin.de
PDF

Phys. Rev. B 112, 085414 – Published 12 August, 2025

DOI: https://doi.org/10.1103/nfd8-xrc4

Abstract

Scanning tunneling microscopy (STM) at 5 K was used to study individual Au atoms adsorbed on the surface of a WSe2 layer grown on epitaxial graphene. In line with theoretical predictions, scanning tunneling spectroscopy measurements reveal that the weakly bound adatom gives rise to an electronic state within the energy band gap of the WSe2 layer. Adatoms in different surface locations show different gap-state energy values that follow a random distribution around the Fermi level of the sample with a standard deviation of ∼50 meV. The location-dependent shift is attributed to spatial variations in disorder potential. Tunneling via the gap state is accompanied by vibrational excitations as apparent from pronounced sideband peaks in the conductance spectra with Poisson-distributed intensities indicating significant electron-phonon coupling with a Huang-Rhys factor of S ≅ 2.8. STM tunneling through single Au adatoms on two-dimensional WSe2 constitutes a model case of resonant double-barrier tunneling accompanied by strong coupling to vibrational degrees of freedom.

View figure in article

Physics Subject Headings (PhySH)

Article Text

Supplemental Material

References (50)

  1. S. Manzeli, D. Ovchinnikov, D. Pasquier, O. V. Yazyev, and A. Kis, 2D transition metal dichalcogenides, Nat. Rev. Mater. 2, 17033 (2017).
  2. M. Koperski, K. Nogajewski, A. Arora, P. Kossacki, and M. Potemski, Single photon emitters in exfoliated WSe2 structures, Nat. Nanotechnol. 10, 503 (2015).
  3. Y. Liu, N. O. Weiss, X. Duan, H.-C. Cheng, Y. Huang, and X. Duan, Van der Waals heterostructures and devices, Nat. Rev. Mater. 1, 16042 (2016).
  4. K. A. Cochrane, J.-H. Lee, C. Kastl, J. B. Haber, T. Zhang, A. Kozhakhmetov, J. A. Robinson, M. Terrones, J. Repp, J. B. Neaton, A. Weber-Bargioni, and B. Schuler, Spin-dependent vibronic response of a carbon radical ion in two-dimensional WS2, Nat. Commun. 12, 7287 (2021).
  5. S. Trishin, C. Lotze, N. Bogdanoff, F. von Oppen, and K. J. Franke, Moiré tuning of spin excitations: Individual Fe atoms on MoS2/Au(111), Phys. Rev. Lett. 127, 236801 (2021).
  6. S. Trishin, C. Lotze, F. Lohss, G. Franceschi, L. I. Glazman, F. von Oppen, and K. J. Franke, Tuning a two-impurity Kondo system by a Moiré superstructure, Phys. Rev. Lett. 130, 176201 (2023).
  7. J. A. Robinson and B. Schuler, Engineering and probing atomic quantum defects in 2D semiconductors: A perspective, Appl. Phys. Lett. 119, 140501 (2021); and references therein.
  8. Y.-C. Lin, D. O. Dumcenco, H.-P. Komsa, Y. Niimi, A. V. Krasheninnikov, Y.-S. Huang, and K. Suenaga, Properties of individual dopant atoms in single-layer MoS2: Atomic structure, migration, and enhanced reactivity, Adv. Mater. 26, 2857 (2014).
  9. X. D. Li, Y. M. Fang, S. Q. Wu, and Z. Z. Zhu, Adsorption of alkali, alkaline-earth, simple and 3d transition metal, and nonmetal atoms on monolayer MoS2, AIP Advances 5, 057143 (2015).
  10. P. Wu, N. Yin, P. Li, W. Cheng, and M. Huang, The adsorption and diffusion behavior of noble metal adatoms (Pd, Pt, Cu, Ag and Au) on a monolayer: A first-principles study, Phys. Chem. Chem. Phys. 19, 20713 (2017).
  11. R. Costa-Amaral, A. Forhat, N. A. M. S. Caturello, and J. L. F. Da Silva, Unveiling the adsorption properties of 3d, 4d, and 5d metal adatoms on the MoS2 monolayer: A DFT-D3 investigation, Surf. Sci. 701, 121700 (2020).
  12. D. Lizzit, P. Khakbaz, F. Driussi, M. Pala, and D. Esseni, Ohmic behavior in metal contacts to n/p-type transition-metal dichalcogenides: Schottky versus tunneling barrier trade-off, ACS Appl. Nano Mater. 6, 5737 (2023); and references therein.
  13. Y. Pan, S. Fölsch, Y.-C. Lin, B. Jariwala, J. A. Robinson, Y. Nie, K. Cho, and R. M. Feenstra, WSe2 homojunctions and quantum dots created by patterned hydrogenation of epitaxial graphene substrates, 2D Mater. 2, 021001 (2019).
  14. C. Zhang, Y. Chen, A. Johnson, M.-Y. Li, L.-J. Li, P. C. Mende, R. M. Feenstra, and C.-K. Shih, Probing critical point energies of transition metal dichalcogenides: Surprising indirect gap of single layer WSe2, Nano Lett. 15, 6494 (2015).
  15. R. Addou, C. M. Smyth, J.-Y. Noh, Y.-C. Lin, Y. Pan, S. M. Eichfeld, S. Fölsch, J. A. Robinson, K. Cho, R. M. Feenstra, and R. M. Wallace, One dimensional metallic edges in atomically thin WSe2 induced by air exposure, 2D Mater. 5, 025017 (2018).
  16. P. Mårtensson and R. M. Feenstra, Geometric and electronic structure of antimony on the GaAs(110) surface studied by scanning tunneling microscopy, Phys. Pev. B 39, 7744 (1989).
  17. R. M. Feenstra, G. R. Frazier, Y. Pan, S. Fölsch, Y.-C. Lin, B. Jariwala, K. Zhang, and J. A. Robinson, Acquisition and analysis of scanning tunneling spectroscopy data – WSe2 monolayer, J. Vac. Sci. Technol. A 39, 011001 (2021).
  18. See Supplemental Material at http://link.aps.org/supplemental/10.1103/nfd8-xrc4 for additional information on tip-induced dimer formation and auxiliary sideband spectra.
  19. G. Binnig, N. Garcia, and H. Rohrer, Conductivity sensitivity of inelastic scanning tunneling microscopy, Phys. Rev. B 32, 1336 (1985).
  20. B. C. Stipe, M. A. Rezaei, and W. Ho, Single-molecule vibrational spectroscopy and microscopy, Science 280, 1732 (1998).
  21. G. V. Nazin, S. W. Wu, and W. Ho, Tunneling rates in electron transport through double-barrier molecular junctions in a scanning tunneling microscope, Proc. Natl. Acad. Sci. USA 102, 8832 (2005).
  22. N. Krane, C. Lotze, G. Reecht, L. Zhang, A. L. Briseno, and K. J. Franke, High-resolution vibronic spectra of molecules on molybdenum disulfide allow for rotamer identification, ACS Nano 12, 11698 (2018).
  23. J. Repp, G. Meyer, S. Paavilainen, F. E. Olsson, and Mats Persson, Scanning tunneling spectroscopy of Cl vacancies in NaCl films: Strong electron-phonon coupling in double-barrier tunneling Junctions, Phys. Rev. Lett. 95, 225503 (2005).
  24. M. Berthe, A. Urbieta, L. Perdigão, B. Grandidier, D. Deresmes, C. Delerue, D. Stiévenard, R. Rurali, N. Lorente, L. Magaud, and P. Ordejón, Electron transport via local polarons at interface atoms, Phys. Rev. Lett. 97, 206801 (2006).
  25. Z. Qiu, K. Vaklinova, P. Huang, M. Grzeszczyk, K. Watanabe, T. Taniguchi, K. S. Novoselov, J. Lu, and M. Koperski, Atomic and electronic structure of defects in hBN: Enhancing single-defect functionalities, ACS Nano 18, 24035 (2024).
  26. J. W. Gadzuk, Inelastic resonance scattering, tunneling, and desorption, Phys. Rev. B 44, 13466 (1991); and references therein.
  27. A. A. Lucas and M. Šunić, Fast-electron spectroscopy of collective excitations in solids, Prog. Surf. Sci. 2, 75 (1972).
  28. A. Baratoff and B. N. J. Perrson, Theory of the local tunneling spectrum of a vibrating adsorbate, J. Vac. Sci. Technol. A6, 331 (1987).
  29. K. Flensberg, Tunneling broadening of vibrational sidebands in molecular transistors, Phys. Rev. B 68, 205323 (2003).
  30. S. Braig and K. Flensberg, Vibrational sidebands and dissipative tunneling in molecular transistors, Phys. Rev. B 68, 205324 (2003).
  31. A. L. Efros, Metal-non-metal transition in heterostructures with thick spacer layers, Solid State Commun. 70, 253 (1989).
  32. C. Metzner, M. Hofmann, and G. H. Döhler, Intersubband transitions of a quasi-two-dimensional electron gas in the strong disorder regime, Phys. Rev. B 58, 7188 (1998).
  33. S. Perraud, K. Kanisawa, Z.-Z. Wang, and T. Fujisawa, Imaging the percolation of localized states in a multisubband two-dimensional electronic system subject to a disorder potential, Phys. Rev. B 76, 195333 (2007).
  34. Y.-C. Lin, B. Jariwala, B. M. Bersch, K. Xu, Y. Nie, B. Wang, S. M. Eichfeld, X. Zhang, T. H. Choudhury, Y. Pan, R. Addou, C. M. Smyth, J. Li, K. Zhang, M. A. Haque, S. Fölsch, R. M. Feenstra, R. M. Wallace, K. Cho, S. K. Fullerton-Shirey et al., Realizing large-scale, electronic-grade two-dimensional semiconductors, ACS Nano 12, 965 (2018).
  35. H. Yu, A. Kutana, and B. I. Yakobson, Carrier delocalization in two-dimensional coplanar p-n junctions of graphene and metal dichalcogenides, Nano Lett. 16, 5032 (2016).
  36. X. Wu, X. Li, Z. Song, C. Berger, and Walt A. de Heer, Weak antilocalization in epitaxial graphene: Evidence for chiral electrons, Phys. Rev. Lett. 98, 136801 (2007).
  37. D. B. Farmer, V. Perebeinos, Y.-M. Lin, C. Dimitrakopoulos, and P. Avouris, Charge trapping and scattering in epitaxial graphene, Phys. Rev. B 84, 205417 (2011).
  38. J. A. Stroscio and D. M. Eigler, Atomic and molecular manipulation with the scanning tunneling microscope, Science 254, 1319 (1991).
  39. M. Paulsson, F. Zahid, and S. Datta, in Nanoscience, Engineering, and Technology Handbook, edited by W. Goddard, D. Brenner, S. Lyshevski, and G. Iafrate (CRC Press, Boca Raton, 2003).
  40. I. Fernández-Torrente, D. Kreikemeyer-Lorenzo, A. Stróżecka, K. J. Franke, and J. I. Pascual, Gating the charge state of single molecules by local electric fields, Phys. Rev. Lett. 108, 036801 (2012).
  41. Y. V. Morozov and M. Kuno, Optical constants and dynamic conductivities of single layer MoS2 MoSe2, and WSe2, Appl. Phys. Lett. 107, 083103 (2015); and references therein.
  42. K. Teichmann, M. Wenderoth, S. Loth, R. G. Ulbrich, J. K. Garleff, A. P. Wijnheijmer, and P. M. Koenraad, Controlled charge switching on a single donor with a scanning tunneling microscope, Phys. Rev. Lett. 101, 076103 (2008).
  43. N. A. Pradhan, N. Liu, C. Silien, and W. Ho, Atomic scale conductance induced by single impurity charging, Phys. Rev. Lett. 94, 076801 (2005).
  44. R. Leturcq, C. Stampfer, K. Inderbitzin, L. Durrer, C. Hierold, E. Mariani, M. G. Schultz, F. von Oppen, and K. Ensslin, Franck–Condon blockade in suspended carbon nanotube quantum dots, Nat. Phys. 5, 327 (2009).
  45. S. Data, Quantum Transport: Atom to Transistor (Cambridge University Press, Cambridge, 2005).
  46. J. Kröger, L. Limot, H. Jensen, R. Berndt, S. Crampin, and E. Pehlke, Surface state electron dynamics of clean and adsorbate-covered metal surfaces studied with the scanning tunneling microscope, Prog. Surf. Sci. 80, 26 (2005).
  47. The thermal broadening is 3.53kT while the instrumental broadening amounts to 1.73Vp with Vp the amplitude of the sinusoidal modulation. The total broadening is then approximated by a Gaussian having a full width at half maximum of wG=(3.53kT/e)2+(1.73Vp)2∫ yielding wG=4.6mV under the experimental conditions T=5 K and Vp=2.5mV.
  48. The peaks corresponding to levels n>5 were pinned to equidistant positions and their width was set to the value obtained from the fit for n=5; the only free parameter left for n>5 was the peak area.
  49. K. Ko, M. Jang, J. Kwon, and J. Suh, Native point defects in 2D transition metal dichalcogenides: A perspective bridging intrinsic physical properties and device applications, J. Appl. Phys. 135, 100901 (2024); and references therein.
  50. J. Marek, J. Kozarik, M. Minarik, A. Chvála, M. Matus, M. Donoval, L. Stuchlikova, and M. Weis, Charge trap states of SiC power TrenchMOS transistor under repetitive unclamped inductive switching stress, Materials 15, 8230 (2022); and references therein.

Outline

Information

Phys. Rev. B 112, 085414– Published 12 August, 2025
  • Received 17 April 2025
  • Revised 26 June 2025
  • Accepted 25 July 2025
Crossmark - Check for updates button
Creative Commons Logo

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

Published by the American Physical Society

Sign In to Your Journals Account

Filter

Filter

Article Lookup

Enter a citation