Nano Research

, Volume 12, Issue 2, pp 303–308 | Cite as

Effective N-methyl-2-pyrrolidone wet cleaning for fabricating high-performance monolayer MoS2 transistors

  • Po-Chun Chen
  • Chih-Pin Lin
  • Chuan-Jie Hong
  • Chih-Hao Yang
  • Yun-Yan Lin
  • Ming-Yang Li
  • Lain-Jong Li
  • Tung-Yuan Yu
  • Chun-Jung Su
  • Kai-Shin Li
  • Yuan-Liang Zhong
  • Tuo-Hung HouEmail author
  • Yann-Wen LanEmail author
Research Article


Two-dimensional semiconductors, such as MoS2 are known to be highly susceptible to diverse molecular adsorbates on the surface during fabrication, which could adversely affect device performance. To ensure high device yield, uniformity and performance, the semiconductor industry has long employed wet chemical cleaning strategies to remove undesirable surface contaminations, adsorbates, and native oxides from the surface of Si wafers. A similarly effective surface cleaning technique for two-dimensional materials has not yet been fully developed. In this study, we propose a wet chemical cleaning strategy for MoS2 by using N-methyl-2-pyrrolidone. The cleaning process not only preserves the intrinsic properties of monolayer MoS2, but also significantly improves the performance of monolayer MoS2 field-effect-transistors. Superior device on current of 12 μA·μm–1 for a channel length of 400 nm, contact resistance of 15 kΩ·μm, field-effect mobility of 15.5 cm2·V–1·s–1, and the average on–off current ratio of 108 were successfully demonstrated


monolayer MoS2 devices standard wet cleaning field-effect transistors N-methyl-2-pyrrolidone 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.



Thanks for the fruitful discussion with Dr. Yao-Jen Lee, and Yi-Ling Jian. This work was supported by the “National Science Council” under contract No. MOST 105-2112-M-003-016-MY3. This work was also in part supported by the “National Nano Device Laboratories”.

Supplementary material

12274_2018_2215_MOESM1_ESM.pdf (2 mb)
Effective N-methyl-2-pyrrolidone wet cleaning for fabricating high-performance monolayer MoS2 transistors


  1. [1]
    Uchida, K.; Watanabe, H.; Kinoshita, A.; Koga, J.; Numata, T.; Takagi, S. Experimental study on carrier transport mechanism in ultrathin-body SOI n- and p-MOSFETs with SOI thickness less than 5 nm. In Proceedings of the IEEE International Electron Devices Meeting, San Francisco, CA, USA, 2002, pp 47–50.CrossRefGoogle Scholar
  2. [2]
    Uchida, K.; Koga, J.; Takagi, S. Experimental study on carrier transport mechanisms in double- and single-gate ultrathin-body MOSFETs—Coulomb scattering, volume inversion, and δTSOI-, induced scattering. In Proceedings of the IEEE International Electron Devices Meeting, Washington, DC, USA, USA, 2003, pp 33.5.1–33.5.4.Google Scholar
  3. [3]
    Schmidt, M.; Lemme, M. C.; Gottlob, H. D. B.; Driussi, F.; Selmi, L.; Kurz, H. Mobility extraction in SOI MOSFETs with sub 1 nm body thickness. Solid-State Electron. 2009, 53, 1246–1251.CrossRefGoogle Scholar
  4. [4]
    Uchida, K.; Takagi, S. Carrier scattering induced by thickness fluctuation of silicon-on-insulator film in ultrathin-body metal–oxide–semiconductor field-effect transistors. Appl. Phys. Lett. 2003, 82, 2916–2918.CrossRefGoogle Scholar
  5. [5]
    Low, T.; Li, M. F.; Fan, W. J.; Ng, S. T.; Yeo, Y. C.; Zhu, C.; Chin, A.; Chan, L.; Kwong, D. L. Impact of surface roughness on silicon and germanium ultra-thin-body MOSFETs. In Proceedings of the IEEE International Electron Devices Meeting, San Francisco, CA, USA, 2004, pp 151–154.Google Scholar
  6. [6]
    Radisavljevic, B.; Whitwick, M. B.; Kis, A. Integrated circuits and logic operations based on single-layer MoS2. ACS Nano 2011, 5, 9934–9938.CrossRefGoogle Scholar
  7. [7]
    Wang, H.; Yu, L. L.; Lee, Y.-H.; Shi, Y. M.; Hsu, A.; Chin, M. L.; Li, L.-J.; Dubey, M.; Kong, J.; Palacios, T. Integrated circuits based on bilayer MoS2 transistors. Nano Lett. 2012, 12, 4674–4680.CrossRefGoogle Scholar
  8. [8]
    Lee, H. S.; Min, S. W.; Chang, Y. G.; Park, M. K.; Nam, T.; Kim, H.; Kim, J. H.; Ryu, S.; Im, S. MoS2 nanosheet phototransistors with thicknessmodulated optical energy gap. Nano Lett. 2012, 12, 3695–3700.CrossRefGoogle Scholar
  9. [9]
    Splendiani, A.; Sun, L.; Zhang, Y. B.; Li, T. S.; Kim, J.; Chim, C. Y.; Galli, G.; Wang, F. Emerging photoluminescence in monolayer MoS2. Nano Lett. 2010, 10, 1271–1275.CrossRefGoogle Scholar
  10. [10]
    Mak, K. F.; Lee, C.; Hone, J.; Shan, J.; Heinz, T. F. Atomically thin MoS2: A new direct-gap semiconductor. Phys. Rev. Lett. 2010, 105, 136805.CrossRefGoogle Scholar
  11. [11]
    He, K. L.; Poole, C.; Mak, K. F.; Shan, J. Experimental demonstration of continuous electronic structure tuning via strain in atomically thin MoS2. Nano Lett. 2013, 13, 2931–2936.CrossRefGoogle Scholar
  12. [12]
    Conley, H. J.; Wang, B.; Ziegler, J. I.; Haglund, R. F., Jr.; Pantelides, S. T.; Bolotin, K. I. Bandgap engineering of strained monolayer and bilayer MoS2. Nano Lett. 2013, 13, 3626–3630.CrossRefGoogle Scholar
  13. [13]
    Castellanos-Gomez, A.; Roldán, R.; Cappelluti, E.; Buscema, M.; Guinea, F.; van der Zant, H. S. J.; Steele, G. A. Local strain engineering in atomically thin MoS2. Nano Lett. 2013, 13, 5361–5366.CrossRefGoogle Scholar
  14. [14]
    Das, S.; Chen, H.-Y.; Penumatcha, A. V.; Appenzeller, J. High performance multilayer MoS2 transistors with scandium contacts. Nano Lett. 2013, 13, 100–105.CrossRefGoogle Scholar
  15. [15]
    Liu, H.; Neal, A. T.; Ye, P. D. Channel length scaling of MoS2 MOSFETs. ACS Nano 2012, 6, 8563–8569.CrossRefGoogle Scholar
  16. [16]
    Liu, H.; Si, M. W.; Najmaei, S.; Neal, A. T.; Du, Y. C.; Ajayan, P. M.; Lou, J.; Ye, P. D. Statistical study of deep submicron dual-gated field-effect transistors on monolayer chemical vapor deposition molybdenum disulfide films. Nano Lett. 2013, 13, 2640–2646.CrossRefGoogle Scholar
  17. [17]
    Li, S.-L.; Wakabayashi, K.; Xu, Y.; Nakaharai, S.; Komatsu, K.; Li, W.-W.; Lin, Y.-F.; Aparecido-Ferreira, A.; Tsukagoshi, K. Thickness-dependent interfacial Coulomb scattering in atomically thin field-effect transistors. Nano Lett. 2013, 13, 3546–3552.CrossRefGoogle Scholar
  18. [18]
    Yang, L. M.; Majumdar, K.; Liu, H.; Du, Y. C.; Wu, H.; Hatzistergos, M.; Hung, P. Y.; Tieckelmann, R.; Tsai, W.; Hobbs, C. et al. Chloride molecular doping technique on 2D materials: WS2 and MoS2. Nano Lett. 2014, 14, 6275–6280.CrossRefGoogle Scholar
  19. [19]
    Kiriya, D.; Tosun, M.; Zhao, P. D.; Kang, J. S.; Javey, A. Air-stable surface charge transfer doping of MoS2 by benzyl viologen. J. Am. Chem. Soc. 2014, 136, 7853–7856.CrossRefGoogle Scholar
  20. [20]
    Kappera, R.; Voiry, D.; Yalcin, S. E.; Branch, B.; Gupta, G.; Mohite, A. D.; Chhowalla, M. Phase-engineered low-resistance contacts for ultrathin MoS2 transistors. Nat. Mater. 2014, 13, 1128–1134.CrossRefGoogle Scholar
  21. [21]
    Jena, D.; Banerjee, K.; Xing, G. H. 2D crystal semiconductors: Intimate contacts. Nat. Mater. 2014, 13, 1076–1078.CrossRefGoogle Scholar
  22. [22]
    Duerloo, K. A. N.; Li, Y.; Reed, E. J. Structural phase transitions in twodimensional Mo- and W-dichalcogenide monolayers. Nat. Commun. 2014, 5, 4214.CrossRefGoogle Scholar
  23. [23]
    Du, Y. C.; Yang, L. M.; Zhang, J. Y.; Liu, H.; Majumdar, K.; Kirsch, P. D.; Ye, P. D. MoS2 field-effect transistors with graphene/metal heterocontacts. IEEE Electron Device Lett. 2014, 35, 599–601.CrossRefGoogle Scholar
  24. [24]
    Liu, Y.; Guo, J.; Wu, Y. C.; Zhu, E. B.; Weiss, N. O.; He, Q. Y.; Wu, H.; Cheng, H.-C.; Xu, Y.; Shakir, I. et al. Pushing the performance limit of sub-100 nm molybdenum disulfide transistors. Nano Lett. 2016, 16, 6337–6342.CrossRefGoogle Scholar
  25. [25]
    English, C. D.; Shine, G.; Dorgan, V. E.; Saraswat, K. C.; Pop, E. Improved contacts to MoS2 transistors by ultra-high vacuum metal deposition. Nano Lett. 2016, 16, 3824–3830.CrossRefGoogle Scholar
  26. [26]
    Ma, N.; Jena, D. Charge scattering and mobility in atomically thin semiconductors. Phys. Rev. X 2014, 4, 011043.Google Scholar
  27. [27]
    Li, H.; Wu, J.; Huang, X.; Yin, Z. Y.; Liu, J. Q.; Zhang, H. A universal, rapid method for clean transfer of nanostructures onto various substrates. ACS Nano 2014, 8, 6563–6570.CrossRefGoogle Scholar
  28. [28]
    Late, D. J.; Liu, B.; Matte, H. S. S. R.; Dravid, V. P.; Rao, C. N. R. Hysteresis in single-layer MoS2 field effect transistors. ACS Nano 2012, 6, 5635–5641.CrossRefGoogle Scholar
  29. [29]
    Park, W.; Park, J.; Jang, J.; Lee, H.; Jeong, H.; Cho, K.; Hong, S.; Lee, T. Oxygen environmental and passivation effects on molybdenum disulfide field effect transistors. Nanotechnology 2013, 24, 095202.CrossRefGoogle Scholar
  30. [30]
    Qiu, H.; Pan, L. J.; Yao, Z. N.; Li, J. J.; Shi, Y.; Wang, X. R. Electrical characterization of back-gated bi-layer MoS2 field-effect transistors and the effect of ambient on their performances. Appl. Phys. Lett. 2012, 100, 123104.CrossRefGoogle Scholar
  31. [31]
    Li, L.; Engel, M.; Farmer, D. B.; Han, S. J.; Wong, H. S. P. High-performance p-type black phosphorus transistor with scandium contact. ACS Nano 2016, 10, 4672–4677.CrossRefGoogle Scholar
  32. [32]
    Yang, L. M.; Qiu, G.; Si, M. W.; Charnas, A. R.; Milligan, C. A.; Zemlyanov, D. Y.; Zhou, H.; Du, Y. C.; Lin, Y. M.; Tsai, W. et al. Few-layer black phosporous PMOSFETs with BN/Al2O3 bilayer gate dielectric: Achieving Ion = 850 µA/µm, gm = 340 µS/µm, and Rc = 0.58 kO·µm. In Proceedings of the 2016 IEEE International Electron Devices Meeting, San Francisco, CA, USA, 2016, pp 5.5.1–5.5.4.CrossRefGoogle Scholar
  33. [33]
    Chang, C. Y.; Sze, S. M. ULSI Technology; McGraw-Hill College: New York, 1996.Google Scholar
  34. [34]
    Jawaid, A.; Nepal, D.; Park, K.; Jespersen, M.; Qualley, A.; Mirau, P.; Drummy, L. F.; Vaia, R. A. Mechanism for liquid phase exfoliation of MoS2. Chem. Mater. 2016, 28, 337–348.CrossRefGoogle Scholar
  35. [35]
    Hernandez, Y.; Nicolosi, V.; Lotya, M.; Blighe, F. M.; Sun, Z. Y.; De, S.; McGovern, I. T.; Holland, B.; Byrne, M.; Gun’Ko, Y. K. et al. High-yield production of graphene by liquid-phase exfoliation of graphite. Nat. Nanotechnol. 2008, 3, 563–568.CrossRefGoogle Scholar
  36. [36]
    Gupta, A.; Arunachalam, V.; Vasudevan, S. Liquid-phase exfoliation of MoS2 nanosheets: The critical role of trace water. J. Phys. Chem. Lett. 2016, 7, 4884–4890.CrossRefGoogle Scholar
  37. [37]
    Thodkar, K.; Thompson, D.; Lüönd, F.; Moser, L.; Overney, F.; Marot, L.; Schönenberger, C.; Jeanneret, B.; Calame, M. Restoring the electrical properties of CVD graphene via physisorption of molecular adsorbates. ACS Appl. Mater. Interfaces 2017, 9, 25014–25022.CrossRefGoogle Scholar
  38. [38]
    Schroder, D. K. Semiconductor Material and Device Characterization, 3rd ed.; John Wiley & Sons: Hoboken, 2006.Google Scholar
  39. [39]
    Yoon, M. H.; Kim, C.; Facchetti, A.; Marks, T. J. Gate dielectric chemical structure-organic field-effect transistor performance correlations for electron, hole, and ambipolar organic semiconductors. J. Am. Chem. Soc. 2006, 128, 12851–12869.CrossRefGoogle Scholar
  40. [40]
    Park, J.-S.; Jeong, J. K.; Chung, H.-J.; Mo, Y.-G.; Kim, H. D. Electronic transport properties of amorphous indium-gallium-zinc oxide semiconductor upon exposure to water. Appl. Phys. Lett. 2008, 92, 072104.CrossRefGoogle Scholar
  41. [41]
    Hu, C. M. Modern Semiconductor Devices for Integrated Circuits; Pearson Prentice Hall: Upper Saddle River, NJ, USA, 2010.Google Scholar
  42. [42]
    Smithe, K. K. H.; English, C. D.; Suryavanshi, S. V; Pop, E. Intrinsic electrical transport and performance projections of synthetic monolayer MoS2 devices. 2D Mater. 2017, 4, 011009.CrossRefGoogle Scholar
  43. [43]
    Cui, X.; Lee, G.-H.; Kim, Y. D.; Arefe, G.; Huang, P. Y.; Lee, C.-H.; Chenet, D. A.; Zhang, X.; Wang, L.; Ye, F. et al. Multi-terminal transport measurements of MoS2 using a van der Waals heterostructure device platform. Nat Nanotechnol. 2015, 10, 534–540.CrossRefGoogle Scholar
  44. [44]
    Cui, X.; Shih, E. M.; Jauregui, L. A.; Chae, S. H.; Kim, Y. D.; Li, B. C.; Sea, D.; Pistunova, K.; Yin, J.; Park, J. H. et al. Low-temperature Ohmic contact to monolayer MoS2 by van der Waals bonded Co/h-BN electrodes. Nano Lett. 2017, 17, 4781–4786.CrossRefGoogle Scholar
  45. [45]
    Liu, W.; Sarkar, D.; Kang, J. H.; Cao, W.; Banerjee, K. Impact of contact on the operation and performance of back-gated monolayer MoS2 fieldeffect- transistors. ACS Nano 2015, 9, 7904–7912.CrossRefGoogle Scholar
  46. [46]
    Allain, A.; Kang, J. H.; Banerjee, K.; Kis, A. Electrical contacts to two-dimensional semiconductors. Nat. Mater. 2015, 14, 1195–1205.CrossRefGoogle Scholar

Copyright information

© Tsinghua University Press and Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  • Po-Chun Chen
    • 1
  • Chih-Pin Lin
    • 2
  • Chuan-Jie Hong
    • 3
  • Chih-Hao Yang
    • 3
  • Yun-Yan Lin
    • 1
  • Ming-Yang Li
    • 4
  • Lain-Jong Li
    • 5
  • Tung-Yuan Yu
    • 6
  • Chun-Jung Su
    • 6
  • Kai-Shin Li
    • 6
  • Yuan-Liang Zhong
    • 3
  • Tuo-Hung Hou
    • 2
    Email author
  • Yann-Wen Lan
    • 1
    Email author
  1. 1.Department of Physics“National Taiwan Normal University”TaipeiTaiwan
  2. 2.Department of Electronics Engineering and Institute of Electronics“National Chiao Tung University”HsinchuTaiwan
  3. 3.Department of Physics and Center for NanotechnologyChung Yuan Christian UniversityChungliTaiwan
  4. 4.Research Center for Applied Sciences“Academia Sinica”TaipeiTaiwan
  5. 5.Physical Sci. and Eng.King Abdullah University of Sci. and TechnologyThuwalKingdom of Saudi Arabia
  6. 6.“National Nano Device Laboratories”“National Applied Research Laboratories”HsinchuTaiwan

Personalised recommendations