Crested two-dimensional transistors

Abstract

Two-dimensional transition metal dichalcogenide (TMD) materials, albeit promising candidates for applications in electronics and optoelectronics1,2,3, are still limited by their low electrical mobility under ambient conditions. Efforts to improve device performance through a variety of routes, such as modification of contact metals4 and gate dielectrics5,6,7,8,9 or encapsulation in hexagonal boron nitride10, have yielded limited success at room temperature. Here, we report a large increase in the performance of TMD field-effect transistors operating under ambient conditions, achieved by engineering the substrate’s surface morphology. For MoS2 transistors fabricated on crested substrates, we observed an almost two orders of magnitude increase in carrier mobility compared to standard devices, as well as very high saturation currents. The mechanical strain in TMDs has been predicted to boost carrier mobility11, and has been shown to influence the local bandgap12,13 and quantum emission properties14 of TMDs. With comprehensive investigation of different dielectric environments and morphologies, we demonstrate that the substrate’s increased corrugation, with its resulting strain field, is the dominant factor driving performance enhancement. This strategy is universally valid for other semiconducting TMD materials, either p-doped or n-doped, opening them up for applications in heterogeneous integrated electronics.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Fig. 1: High-performance MoS2 FET on c-SiNx.
Fig. 2: Substrate morphology dependence of MoS2 FETs.
Fig. 3: Pre-patterning method for improvement of FET performance on a SiO2 substrate.
Fig. 4: FET performance of other TMDs on both c-SiNx and standard SiO2 substrates.

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.

References

  1. 1.

    Chhowalla, M. et al. The chemistry of two-dimensional layered transition metal dichalcogenide nanosheets. Nat. Chem. 5, 263–275 (2013).

  2. 2.

    Wang, Q. H., Kalantar-Zadeh, K., Kis, A., Coleman, J. N. & Strano, M. S. Electronics and optoelectronics of two-dimensional transition metal dichalcogenides. Nat. Nanotechnol. 7, 699–712 (2012).

  3. 3.

    Butler, S. Z. et al. Progress, challenges, and opportunities in two-dimensional materials beyond graphene. ACS Nano 7, 2898–2926 (2013).

  4. 4.

    Das, S., Chen, H.-Y., Penumatcha, A. V. & Appenzeller, J. High performance multilayer MoS2 transistors with scandium contacts. Nano Lett. 13, 100–105 (2013).

  5. 5.

    Lee, G.-H. et al. Flexible and transparent MoS2 field-effect transistors on hexagonal boron nitride–graphene heterostructures. ACS Nano 7, 7931–7936 (2013).

  6. 6.

    Chan, M. Y. et al. Suppression of thermally activated carrier transport in atomically thin MoS2 on crystalline hexagonal boron nitride substrates. Nanoscale 5, 9572–9576 (2013).

  7. 7.

    Kim, S. et al. High-mobility and low-power thin-film transistors based on multilayer MoS2 crystals. Nat. Commun. 3, 1011 (2012).

  8. 8.

    Bao, W., Cai, X., Kim, D., Sridhara, K. & Fuhrer, M. S. High mobility ambipolar MoS2 field-effect transistors: substrate and dielectric effects. Appl. Phys. Lett. 102, 042104 (2013).

  9. 9.

    Chang, H.-Y. et al. High-performance, highly bendable MoS2 transistors with high-k dielectrics for flexible low-power systems. ACS Nano 7, 5446–5452 (2013).

  10. 10.

    Cui, X. et al. Multi-terminal transport measurements of MoS2 using a van der Waals heterostructure device platform. Nat. Nanotechnol. 10, 534–540 (2015).

  11. 11.

    Ge, Y., Wan, W., Feng, W., Di, X. & Yao, Y. Effect of doping and strain modulations on electron transport in monolayer MoS2. Phys. Rev. B 90, 035414 (2014).

  12. 12.

    Shin, B. G. et al. Indirect bandgap puddles in monolayer MoS2 by substrate‐induced local strain. Adv. Mater. 28, 9378–9384 (2016).

  13. 13.

    Krustok, J. et al. Optical study of local strain related disordering in CVD-grown MoSe2 monolayers. Appl. Phys. Lett. 109, 253106 (2016).

  14. 14.

    Palacios-Berraquero, C. et al. Large-scale quantum-emitter arrays in atomically thin semiconductors. Nat. Commun. 8, 15093 (2017).

  15. 15.

    Liu, H., Neal, A. T. & Ye, P. D. Channel length scaling of MoS2 MOSFETs. ACS Nano 6, 8563–8569 (2012).

  16. 16.

    Kappera, R. et al. Phase-engineered low-resistance contacts for ultrathin MoS2 transistors. Nat. Mater. 13, 1128–1134 (2014).

  17. 17.

    Novoselov, K. S. et al. Two-dimensional atomic crystals. Proc. Natl Acad. Sci. USA 102, 10451–10453 (2005).

  18. 18.

    Ghatak, S., Pal, A. N. & Ghosh, A. Nature of electronic states in atomically thin MoS2 field-effect transistors. ACS Nano 5, 7707–7712 (2011).

  19. 19.

    Gomez, L., Aberg, I. & Hoyt, J. L. Electron transport in strained-silicon directly on insulator ultrathin-body n-MOSFETs with body thickness ranging from 2 to 25 nm. IEEE Electron. Dev. Lett. 28, 285–287 (2007).

  20. 20.

    Kaasbjerg, K., Thygesen, K. S. & Jacobsen, K. W. Phonon-limited mobility in n-type single-layer MoS2 from first principles. Phys. Rev. B 85, 115317 (2012).

  21. 21.

    Yoon, Y., Ganapathi, K. & Salahuddin, S. How good can monolayer MoS2 transistors be? Nano Lett. 11, 3768–3773 (2011).

  22. 22.

    Ma, N. & Jena, D. Charge scattering and mobility in atomically thin semiconductors. Phys. Rev. X 4, 011043 (2014).

  23. 23.

    Qi, J., Li, X., Qian, X. & Feng, J. Bandgap engineering of rippled MoS2 monolayer under external electric field. Appl. Phys. Lett. 102, 173112 (2013).

  24. 24.

    Conley, H. J. et al. Bandgap engineering of strained monolayer and bilayer MoS2. Nano Lett. 13, 3626–3630 (2013).

  25. 25.

    Guzman, D. M. & Strachan, A. Role of strain on electronic and mechanical response of semiconducting transition-metal dichalcogenide monolayers: an ab-initio study. J. Appl. Phys. 115, 243701 (2014).

  26. 26.

    Dong, L. et al. Theoretical study on strain induced variations in electronic properties of 2H-MoS2 bilayer sheets. Appl. Phys. Lett. 104, 053107 (2014).

  27. 27.

    Mohammad Tabatabaei, S., Noei, M., Khaliji, K., Pourfath, M. & Fathipour, M. A first-principles study on the effect of biaxial strain on the ultimate performance of monolayer MoS2-based double gate field effect transistor. J. Appl. Phys. 113, 163708 (2013).

  28. 28.

    Harada, N., Sato, S. & Yokoyama, N. Computational study on electrical properties of transition metal dichalcogenide field-effect transistors with strained channel. J. Appl. Phys. 115, 034505 (2014).

  29. 29.

    Wang, Y., Cong, C., Qiu, C. & Yu, T. Raman spectroscopy study of lattice vibration and crystallographic orientation of monolayer MoS2 under uniaxial strain. Small 9, 2857–2861 (2013).

  30. 30.

    Zhang, K. et al. Self-induced uniaxial strain in MoS2 monolayers with local van der Waals-stacked interlayer interactions. ACS Nano 9, 2704–2710 (2015).

  31. 31.

    Jung, Y. S. & Ross, C. A. Orientation-controlled self-assembled nanolithography using a polystyrene−polydimethylsiloxane block copolymer. Nano Lett. 7, 2046–2050 (2007).

  32. 32.

    Bedell, S. W., Khakifirooz, A. & Sadana, D. K. Strain scaling for CMOS. MRS Bull. 39, 131–137 (2014).

Download references

Acknowledgements

S.G. acknowledges support from the National Research Foundation, Prime Minister’s Office, Singapore, under the NRF Fellowship Program (award no. NRF-NRFF2012-09) and Competitive Research Program (award no. NRF-CRP13-2014-03). L.T. acknowledges use of facilities in the laboratories of L. K. Ping and C. Wei at the National University of Singapore.

Author information

T.L., S.L. and S.G. designed the project. T.L., S.L. and K.-H.T. prepared substrates and two-probe devices. T.L., S.L. and H.S. performed the two-probe measurements and analysed the results. T.L. and L.C. fabricated Hall bar devices, performed Hall measurements and analysed the results. T.L. and D.X. fabricated devices, performed four-probe measurements and analysed the results. T.L., S.L. and S.G. wrote the manuscript, with input from other authors. All authors contributed to discussions.

Correspondence to Slaven Garaj.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Further reading