Ambipolar field effect in the ternary topological insulator (BixSb1–x)2Te3 by composition tuning


Topological insulators exhibit a bulk energy gap and spin-polarized surface states that lead to unique electronic properties1,2,3,4,5,6,7,8,9, with potential applications in spintronics and quantum information processing. However, transport measurements have typically been dominated by residual bulk charge carriers originating from crystal defects or environmental doping10,11,12, and these mask the contribution of surface carriers to charge transport in these materials. Controlling bulk carriers in current topological insulator materials, such as the binary sesquichalcogenides Bi2Te3, Sb2Te3 and Bi2Se3, has been explored extensively by means of material doping8,9,11 and electrical gating13,14,15,16, but limited progress has been made to achieve nanostructures with low bulk conductivity for electronic device applications. Here we demonstrate that the ternary sesquichalcogenide (BixSb1–x)2Te3 is a tunable topological insulator system. By tuning the ratio of bismuth to antimony, we are able to reduce the bulk carrier density by over two orders of magnitude, while maintaining the topological insulator properties. As a result, we observe a clear ambipolar gating effect in (BixSb1–x)2Te3 nanoplate field-effect transistor devices, similar to that observed in graphene field-effect transistor devices17. The manipulation of carrier type and density in topological insulator nanostructures demonstrated here paves the way for the implementation of topological insulators in nanoelectronics and spintronics.

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Figure 1: (BixSb1–x)2Te3, a tunable topological insulator system with a single Dirac cone of surface states.
Figure 2: Characterization of (BixSb1–x)2Te3 nanoplates.
Figure 3: Ambipolar field effect in ultrathin nanoplates of (BixSb1–x)2Te3.
Figure 4: Temperature-dependent field effect in (BixSb1–x)2Te3 nanoplates.


  1. 1

    Moore, J. E. The birth of topological insulators. Nature 464, 194–198 (2010).

    CAS  Article  Google Scholar 

  2. 2

    Hasan, M. Z. & Kane, C. L. Colloquium: topological insulators. Rev. Mod. Phys. 82, 3045–3067 (2010).

    CAS  Article  Google Scholar 

  3. 3

    Qi, X-L. & Zhang, S-C. Topological insulators and superconductors. Preprint at (2010).

  4. 4

    Bernevig, B. A., Hughes, T. L. & Zhang, S-C. Quantum spin Hall effect and topological phase transition in HgTe quantum wells. Science 314, 1757–1761 (2006).

    CAS  Article  Google Scholar 

  5. 5

    Konig, M. et al. Quantum spin Hall insulator state in HgTe quantum wells. Science 318, 766–770 (2007).

    Article  Google Scholar 

  6. 6

    Zhang, H. et al. Topological insulators in Bi2Se3, Bi2Te3 and Sb2Te3 with a single Dirac cone on the surface. Nature Phys. 5, 438–442 (2009).

    CAS  Article  Google Scholar 

  7. 7

    Xia, Y. et al. Observation of a large-gap topological-insulator class with a single Dirac cone on the surface. Nature Phys. 5, 398–402 (2009).

    CAS  Article  Google Scholar 

  8. 8

    Chen, Y. L. et al. Experimental realization of a three-dimensional topological insulator, Bi2Te3 . Science 325, 178–181 (2009).

    CAS  Article  Google Scholar 

  9. 9

    Hsieh, D. et al. A tunable topological insulator in the spin helical Dirac transport regime. Nature 460, 1101–1105 (2009).

    CAS  Article  Google Scholar 

  10. 10

    Analytis, J. G. et al. Bulk Fermi surface coexistence with Dirac surface state in Bi2Se3: a comparison of photoemission and Shubnikov–de Haas measurements. Phys. Rev. B 81, 205407 (2010).

    Article  Google Scholar 

  11. 11

    Analytis, J. G. et al. Two-dimensional surface state in the quantum limit of a topological insulator. Nature Phys. 6, 960–964 (2010).

    CAS  Article  Google Scholar 

  12. 12

    Kong, D. et al. Rapid surface oxidation as a source of surface degradation factor for Bi2Se3 . ACS Nano 5, 4698–4703 (2011).

    CAS  Article  Google Scholar 

  13. 13

    Chen, J. et al. Gate-voltage control of chemical potential and weak antilocalization in Bi2Se3 . Phys. Rev. Lett. 105, 176602 (2010).

    CAS  Article  Google Scholar 

  14. 14

    Checkelsky, J. G., Hor, Y. S., Cava, R. J. & Ong, N. P. Bulk band gap and surface state conduction observed in voltage-tuned crystals of the topological insulator Bi2Se3 . Phys. Rev. Lett. 106, 196801 (2011).

    CAS  Article  Google Scholar 

  15. 15

    Chen, J. et al. Tunable surface conductivity in Bi2Se3 revealed in diffusive electron transport. Phys. Rev. B 83, 241304 (2011).

    Article  Google Scholar 

  16. 16

    Steinberg, H., Gardner, D. R., Lee, Y. S. & Jarillo-Herrero, P. Surface state transport and ambipolar electric field effect in Bi2Se3 nanodevices. Nano Lett. 10, 5032–5036 (2010).

    CAS  Article  Google Scholar 

  17. 17

    Novoselov, K. S. et al. Electric field effect in atomically thin carbon films. Science 306, 666–669 (2004).

    CAS  Article  Google Scholar 

  18. 18

    Hsieh, D. et al. Observation of time-reversal-protected single-Dirac-cone topological-insulator states in Bi2Te3 and Sb2Te3 . Phys. Rev. Lett. 103, 146401 (2009).

    CAS  Article  Google Scholar 

  19. 19

    Alpichshev, Z. et al. STM imaging of electronic waves on the surface of Bi2Te3: topologically protected surface states and hexagonal warping effects. Phys. Rev. Lett. 104, 016401 (2010).

    Article  Google Scholar 

  20. 20

    Zhang, Y. et al. Crossover of the three-dimensional topological insulator Bi2Se3 to the two-dimensional limit. Nature Phys. 6, 584–588 (2010).

    Article  Google Scholar 

  21. 21

    Peng, H. et al. Aharonov–Bohm interference in topological insulator nanoribbons. Nature Mater. 9, 225–229 (2010).

    CAS  Article  Google Scholar 

  22. 22

    Qu, D-X., Hor, Y. S., Xiong, J., Cava, R. J. & Ong, N. P. Quantum oscillations and Hall anomaly of surface states in the topological insulator Bi2Te3 . Science 329, 821–824 (2010).

    CAS  Article  Google Scholar 

  23. 23

    Xiu, F. et al. Manipulating surface states in topological insulator nanoribbons. Nature Nanotech. 6, 216–221 (2011).

    CAS  Article  Google Scholar 

  24. 24

    Fu, L. Hexagonal warping effects in the surface states of the topological insulator Bi2Te3 . Phys. Rev. Lett. 103, 266801 (2009).

    Article  Google Scholar 

  25. 25

    Xu, S-Y. et al. Topological phase transition and texture inversion in a tunable topological insulator. Science 332, 560–564 (2011).

    CAS  Article  Google Scholar 

  26. 26

    Kong, D. et al. Few-layer nanoplates of Bi2Se3 and Bi2Te3 with highly tunable chemical potential. Nano Lett. 10, 2245–2250 (2010).

    CAS  Article  Google Scholar 

  27. 27

    Kim, D. et al. Minimum conductivity and charge inhomogeneity in Bi2Se3 in the topological regime. Preprint at (2011).

  28. 28

    Liu, C-X. et al. Oscillatory crossover from two-dimensional to three-dimensional topological insulators. Phys. Rev. B 81, 041307 (2010).

    Article  Google Scholar 

  29. 29

    Li, Y. Y. et al. Intrinsic topological insulator Bi2Te3 thin films on Si and their thickness limit. Adv. Mater. 22, 4002–4007 (2010).

    CAS  Article  Google Scholar 

  30. 30

    Cho, S., Butch, N. P., Paglione, J. & Fuhrer, M. S. Insulating behavior in ultrathin bismuth selenide field effect transistors. Nano Lett. 11, 1925–1927 (2011).

    CAS  Article  Google Scholar 

  31. 31

    Zhang, J. et al. Dirac band engineering in (Bi1–xSbx)2Te3 ternary topological insulators. Preprint at (2011).

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Y.C. acknowledges support from the Keck Foundation, a DARPA MESO project (no. N66001-11-1-4105) and a King Abdullah University of Science and Technology (KAUST) Investigator Award (no. KUS-l1-001-12). Y.L.C. acknowledges support from a DARPA MESO project (no. N66001-11-1-4105). Z.K.L., Z.X.S., Y.L.C., J.G.A. and I.R.F. acknowledge support from Department of Energy, Office of Basic Energy Science (contract DE-AC02-76SF00515). K.L. acknowledges support from the KAUST Postdoctoral Fellowship (no. KUS-F1-033-02).

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D.K., Y.L.C. and Y.C. conceived the experiments. Y.L.C. and Z.K.L. carried out ARPES measurements. J.G.A. synthesized and characterized bulk single crystals. Q.F.Z. performed electronic structure calculations. D.K. and J.J.C. carried out synthesis, structural characterization and device fabrication for nanoplates. D.K., K.L., J.J.C., S.S.H. and K.J.K. carried out transport measurements and analyses. All authors contributed to the scientific planning and discussions.

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Correspondence to Yi Cui.

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Kong, D., Chen, Y., Cha, J. et al. Ambipolar field effect in the ternary topological insulator (BixSb1–x)2Te3 by composition tuning. Nature Nanotech 6, 705–709 (2011).

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