Moiré-related in-gap states in a twisted MoS2/graphite heterojunction
Source abstract
Abstract
Abstract This report presents a series of low-temperature (4.5 K) scanning tunneling microscopy and spectroscopy experimental results on monolayer MoS2 deposited on highly oriented pyrolytic graphite using chemical vapor deposition. To reveal the detailed connection between atomic morphology and conductivity in twisted MoS2/graphite heterojunctions, we employ high-sensitivity tunneling spectroscopy measurements by choosing a reduced tip-sample distance. We discern previously unobserved conductance peaks within the band gap range of MoS2, and by comparing the tunneling spectra from MoS2 grains of varying rotation with respect to the substrate, show that these features have small but non-negligible dependence on the moiré superstructure. Furthermore, within a single moiré supercell, atomically resolved tunneling spectroscopy measurements show that the spectra between the moiré high and low areas are also distinct. These in-gap states are shown to have an energy shift attributed to their local lattice strain, matching corresponding behavior of the conduction band edge, and we therefore infer that these features are intrinsic to the density of states, rather than experimental artifacts, and attribute them to the twisted stacking and local strain energy of the MoS2/graphite heterointerface.
Source: crossref · Quality: baseline
Research context
OpenAlex topics: 2D Materials and Applications · Graphene research and applications · Surface and Thin Film Phenomena
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
References (44)
Show source-provided references
1. Bromley, R. A., Murray, R. B. & Yoffe, A. D. The band structure of some transition metal dichalcogenides: III. Group VI A: trigonal prism materials. J. Phys. C Solid State Phys. 5, 759–778 (1972).10.1088/0022-3719/5/7/007 ↗
2. Böker, T. et al. Band structure of MoS2, MoSe2, and α -MoTe2: Angle-resolved photoelectron spectroscopy and ab initio calculations. Phys. Rev. B 64, 235305 (2001).10.1103/PhysRevB.64.235305 ↗
3. Coehoorn, R. et al. Electronic structure of MoSe2, MoS2, and WSe2. I. Band-structure calculations and photoelectron spectroscopy. Phys. Rev. B 35, 6195–6202 (1987).10.1103/PhysRevB.35.6195 ↗
4. Mattheiss, L. F. Band structures of transition-metal-dichalcogenide layer compounds. Phys. Rev. B 8, 3719–3740 (1973).10.1103/PhysRevB.8.3719 ↗
5. Mak, K. F., Lee, C., Hone, J., Shan, J. & Heinz, T. F. Atomically thin MoS2: A new direct-gap semiconductor. Phys. Rev. Lett. 105, 136805 (2010).10.1103/PhysRevLett.105.136805 ↗
6. Geim, A. K. & Grigorieva, I. V. Van der Waals heterostructures. Nature 499, 419–425 (2013).10.1038/nature12385 ↗
7. Rong, Z. Y. & Kuiper, P. Electronic effects in scanning tunneling microscopy: Moiré pattern on a graphite surface. Phys. Rev. B 48, 17427–17431 (1993).10.1103/PhysRevB.48.17427 ↗
8. de Parga, A. L. V. et al. Periodically rippled graphene: Growth and spatially resolved electronic structure. Phys. Rev. Lett. 100, 056807 (2008).10.1103/PhysRevLett.100.056807 ↗
9. Stradi, D. et al. Electron localization in epitaxial graphene on Ru(0001) determined by moiré corrugation. Phys. Rev. B 85, 121404 (2012).10.1103/PhysRevB.85.121404 ↗
10. Wallbank, J. R., Mucha-Kruczyński, M. & Fal’ko, V. I. Moiré minibands in graphene heterostructures with almost commensurate 3 × 3 hexagonal crystals. Phys. Rev. B 88, 155415 (2013).10.1103/PhysRevB.88.155415 ↗
11. Bistritzer, R. & MacDonald, A. H. Moiré bands in twisted double-layer graphene. Proc. Natl. Acad. Sci. USA 108, 12233–12237 (2011).10.1073/pnas.1108174108 ↗
12. Landgraf, W., Shallcross, S., Turschmann, K., Weckbecker, D. & Pankratov, O. Electronic structure of twisted graphene flakes. Phys. Rev. B 87, 075433 (2013).10.1103/PhysRevB.87.075433 ↗
13. Yin, L.-J. et al. Tuning structures and electronic spectra of graphene layers with tilt grain boundaries. Phys. Rev. B 89, 205410 (2014).10.1103/PhysRevB.89.205410 ↗
14. Vozmediano, M. A. H., González, J., Guinea, F., Alvarez, J. V. & Valenzuela, B. Properties of electrons near a Van Hove singularity. J. Phys. Chem. Solids 63, 2295–2297 (2002).10.1016/S0022-3697(02)00230-5 ↗
15. Dean, C. R. et al. Hofstadter’s butterfly and the fractal quantum Hall effect in moiré superlattices. Nature 497, 598–602 (2013).10.1038/nature12186 ↗
16. Castro Neto, A. H., Guinea, F., Peres, N. M. R., Novoselov, K. S. & Geim, A. K. The electronic properties of graphene. Rev. Mod. Phys. 81, 109–162 (2009).10.1103/RevModPhys.81.109 ↗
17. Luican, A. et al. Single-layer behavior and its breakdown in twisted graphene layers. Phys. Rev. Lett. 106, 126802 (2011).10.1103/PhysRevLett.106.126802 ↗
18. Lopes Dos Santos, J. M., Peres, N. M. & Castro Neto, A. H. Graphene bilayer with a twist: electronic structure. Phys. Rev. Lett. 99, 256802 (2007).10.1103/PhysRevLett.99.256802 ↗
19. Li, G. et al. Observation of Van Hove singularities in twisted graphene layers. Nat. Phys. 6, 109–113 (2010).10.1038/nphys1463 ↗
20. Zhang, X. & Luo, H. Scanning tunneling spectroscopy studies of angle-dependent van Hove singularities on twisted graphite surface layer. Appl. Phys. Lett. 103, 231602 (2013).10.1063/1.4839419 ↗
21. Flores, M., Cisternas, E., Correa, J. D. & Vargas, P. Moiré patterns on STM images of graphite induced by rotations of surface and subsurface layers. Chem. Phys. 423, 49–54 (2013).10.1016/j.chemphys.2013.06.022 ↗
22. Zhang, C., Johnson, A., Hsu, C.-L., Li, L.-J. & Shih, C.-K. Direct imaging of band profile in single layer MoS2 on graphite: quasiparticle energy gap, metallic edge states, and edge band bending. Nano Lett. 14, 2443–2447 (2014).10.1021/nl501133c ↗
23. Huang, Y. L. et al. Bandgap tunability at single-layer molybdenum disulphide grain boundaries. Nat. Commun. 6, 6298 (2015).10.1038/ncomms7298 ↗
24. Lu, C.-I. et al. Graphite edge controlled registration of monolayer MoS2 crystal orientation. Appl. Phys. Lett. 106, 181904 (2015).10.1063/1.4919923 ↗
25. Liu, X. et al. Rotationally commensurate growth of MoS2 on epitaxial graphene. ACS Nano 10, 1067–1075 (2016).10.1021/acsnano.5b06398 ↗
26. Koós, A. A. et al. STM study of the MoS2 flakes grown on graphite: A model system for atomically clean 2D heterostructure interfaces. Carbon 105, 408–415 (2016).10.1016/j.carbon.2016.04.069 ↗
27. Diaz, H. C. et al. Direct observation of interlayer hybridization and Dirac relativistic carriers in graphene/MoS2 van der Waals heterostructures. Nano Lett. 15, 1135–1140 (2015).10.1021/nl504167y ↗
28. Pierucci, D. et al. Band alignment and minigaps in monolayer MoS2-graphene van der Waals heterostructures. Nano Lett. 16, 4054–4061 (2016).10.1021/acs.nanolett.6b00609 ↗
29. Wang, Z., Chen, Q. & Wang, J. Electronic structure of twisted bilayers of graphene/MoS2 and MoS2/MoS2. J. Phys. Chem. C 119, 4752 (2015).10.1021/jp507751p ↗
30. Li, X. D. et al. Structural and electronic properties of superlattice composed of graphene and monolayer MoS2. J. Phys. Chem. C 117, 15347–15353 (2013).10.1021/jp404080z ↗
31. Feenstra, R. M. & Stroscio, J. A. Tunneling spectroscopy of the GaAs(110) surface. J. Vac. Sci. Technol. B 5, 923929 (1987).10.1116/1.583691 ↗
32. Merino, P., Švec, M., Pinardi, A. L., Otero, G. & Martin-Gago, J. A. Strain-driven moiré superstructures of epitaxial graphene on transition metal surfaces. ACS Nano 5, 5627–5634 (2011).10.1021/nn201200j ↗
33. Chiu, M.-H. et al. Determination of band alignment in the single-layer MoS2/WSe2 heterojunction. Nat. Commun. 6, 7666 (2015).10.1038/ncomms8666 ↗
34. Karunadasa, H. I. et al. A Molecular MoS2 edge site mimic for catalytic hydrogen generation. Science 335, 698–702 (2012).10.1126/science.1215868 ↗
35. Lauritsen, J. V. et al. Size-dependent structure of MoS2 nanocrystals. Nat. Nanotechnol. 2, 53–58 (2007).10.1038/nnano.2006.171 ↗
36. Yang, H.-H. et al. Digitized charge transfer magnitude determined by metal-organic coordination number. ACS Nano 7, 2814–2819 (2013).10.1021/nn4003715 ↗
37. Joucken, F. et al. Localized state and charge transfer in nitrogen-doped graphene. Phys. Rev. B 85, 161408 (R) (2012).10.1103/PhysRevB.85.161408 ↗
38. Dombrowski, R., Steinebach, C., Wittneven, C., Morgenstern, M. & Wiesendanger, R. Tip-induced band bending by scanning tunneling spectroscopy of the states of the tip-induced quantum dot on InAs(110). Phys. Rev. B 59, 8043–8048 (1999).10.1103/PhysRevB.59.8043 ↗
39. Ugeda, M. M. et al. Giant bandgap renormalization and excitonic effect in a monolayer transition metal dichalcogenide semiconductor. Nat. Mater. 13, 1091–1095 (2014).10.1038/nmat4061 ↗
40. Kobayashi, K. Moiré pattern in scanning tunneling microscopy: Mechanism in observation of subsurface nanostructures. Phys. Rev. B 53, 11091–11099 (1996).10.1103/PhysRevB.53.11091 ↗
41. Ayers, J. E., Kujofsa, T., Rago, P. & Raphael, J. Heteroepitaxy of Semiconductors: Theory, Growth, and Characterization (CRC press, Boca Raton, FL, 2007).10.1201/9781420006643 ↗
42. Shen, J., Johnston, S., Shang, S. & Anderson, T. J. Calculated strain energy of hexagonal epitaxial thin films. J. Cryst. Growth 240, 6–13 (2002).10.1016/S0022-0248(01)02209-6 ↗
43. Lee, Y.-H. et al. Synthesis of large-area MoS2 atomic layers with chemical vapor deposition. Adv. Mater. 24, 2320–2325 (2012).10.1002/adma.201104798 ↗
44. Horcas, I. et al. WSXM: A software for scanning probe microscopy and a tool for nanotechnology. Rev. Sci. Instrum. 78, 013705 (2007).10.1063/1.2432410 ↗