Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Buckled two-dimensional Xene sheets

Abstract

Silicene, germanene and stanene are part of a monoelemental class of two-dimensional (2D) crystals termed 2D-Xenes (X = Si, Ge, Sn and so on) which, together with their ligand-functionalized derivatives referred to as Xanes, are comprised of group IVA atoms arranged in a honeycomb lattice — similar to graphene but with varying degrees of buckling. Their electronic structure ranges from trivial insulators, to semiconductors with tunable gaps, to semi-metallic, depending on the substrate, chemical functionalization and strain. More than a dozen different topological insulator states are predicted to emerge, including the quantum spin Hall state at room temperature, which, if realized, would enable new classes of nanoelectronic and spintronic devices, such as the topological field-effect transistor. The electronic structure can be tuned, for example, by changing the group IVA element, the degree of spin–orbit coupling, the functionalization chemistry or the substrate, making the 2D-Xene systems promising multifunctional 2D materials for nanotechnology. This Perspective highlights the current state of the art and future opportunities in the manipulation and stability of these materials, their functions and applications, and novel device concepts.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Figure 1: The 2D-Xene odyssey.
Figure 2: Topology as a paradigm shift in nanoelectronics.
Figure 3: The topological bit and emerging physics based on broken symmetry.

References

  1. 1

    Fiori, G. et al. Electronics based on two-dimensional materials. Nat. Nanotech. 9, 768 (2014).

    CAS  Article  Google Scholar 

  2. 2

    Ferrari, A. C. et al. Science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems. Nanoscale 7, 4598 (2015).

    CAS  Google Scholar 

  3. 3

    Akinwande, D. et al. Large-area graphene electrodes: using CVD to facilitate applications in commercial touchscreens, flexible nanoelectronics, and neural interfaces. IEEE Nanotechnol. Magazine 9, 6 (2015).

    Google Scholar 

  4. 4

    Balendhran, S., Walia, S., Nili, H., Sriram, S. & Bhaskaran, M. Elemental analogues of graphene: silicene, germanene, stanene, and phosphorene. Small 11, 640 (2015).

    CAS  Google Scholar 

  5. 5

    Takaeda, K. & Shiraishi, K. Theoretical possibility of stage corrugation in Si and Ge analogs of graphite. Phys. Rev. B 50, 14916 (1994).

    Google Scholar 

  6. 6

    Cahangirov, S., Topsakal, M., Akturk, E., Sahin, H. & Ciraci, S. Two- and one-dimensional honeycomb structures of silicon and germanium. Phys. Rev. Lett. 102, 236804 (2009).

    CAS  Google Scholar 

  7. 7

    Guzman-Verri, G. G. & Voon, L. C. L. Y. Electronic structure of silicon-based nanostructures. Phys. Rev. B 76, 075131 (2007).

    Google Scholar 

  8. 8

    Grazianetti, C., Cinquanta, E. & Molle, A. Two-dimensional silicon: the advent of silicene. 2D Mater. 3, 012001 (2016).

    Google Scholar 

  9. 9

    Liu, C. C., Feng, W. X. & Yao, Y. G. Quantum spin Hall effect in silicene and two-dimensional germanium. Phys. Rev. Lett. 107, 076802 (2011).

    Google Scholar 

  10. 10

    Kane, C. L. & Mele, E. J. Quantum spin Hall effect in graphene. Phys. Rev. Lett. 95, 226801 (2015).

    Google Scholar 

  11. 11

    Houssa, M., Dimoulas, A. & Molle, A. Silicene: a review of recent experimental and theoretical investigations. J. Phys. Cond. Matt. 27, 253002 (2015).

    CAS  Google Scholar 

  12. 12

    Xu, Y. et al. Large-gap quantum spin Hall insulators in tin films. Phys. Rev. Lett. 111, 136804 (2013).

    Google Scholar 

  13. 13

    van den Broek, B. et al. Two-dimensional hexagonal tin: ab initio geometry, stability, electronic structure and functionalization. 2D Mater. 1, 021004 (2014).

    Google Scholar 

  14. 14

    Vogt, P. et al. Silicene: compelling experimental evidence for graphenelike two-dimensional silicon. Phys. Rev. Lett. 108, 155501 (2012).

    Article  Google Scholar 

  15. 15

    Lin, C. L. et al. Structure of silicene grown on Ag(111). Appl. Phys. Express 5, 045802 (2012).

    Google Scholar 

  16. 16

    Feng, B. J. et al. Evidence of silicene in honeycomb structures of silicon on Ag(111). Nano Lett. 12, 3507 (2012).

    CAS  Google Scholar 

  17. 17

    Chiappe, D., Grazianetti, C., Tallarida, G., Fanciulli, M. & Molle, A. Local electronic properties of corrugated silicene phases. Adv. Mater. 24, 5088 (2012).

    CAS  Google Scholar 

  18. 18

    Meng, L. et al. Buckled silicene formation on Ir(111). Nano Lett. 13, 685 (2013).

    CAS  Google Scholar 

  19. 19

    Fleurence, A. et al. Experimental evidence for epitaxial silicene on diboride thin films. Phys. Rev. Lett. 108, 245501 (2012).

    Google Scholar 

  20. 20

    Scalise, E. et al. Vibrational properties of epitaxial silicene layers on (111)Ag. Appl. Surf. Sci. 291, 113 (2014).

    CAS  Google Scholar 

  21. 21

    Tsoutsou, D., Xenogiannopoulou, E., Golias, E., Tsipas, P. & Dimoulas, A. Evidence for hybrid surface metallic band in (4 × 4) silicene on Ag(111). Appl. Phys. Lett. 103, 231604 (2013).

    Google Scholar 

  22. 22

    Davila, M. E., Xian, L., Cahangirov, S., Rubio, A. & Le Lay, G. Germanene: a novel two-dimensional germanium allotrope akin to graphene and silicene. New J. Phys. 16, 095002 (2014).

    Google Scholar 

  23. 23

    Li, L. F. et al. Buckled germanene formation on Pt(111). Adv. Mater. 26, 4820 (2014).

    CAS  Google Scholar 

  24. 24

    Derivaz, M. et al. Continuous germanene layer on Al(111). Nano Lett. 15, 2510 (2015).

    CAS  Google Scholar 

  25. 25

    Bampoulis, P. et al. Germanene termination of Ge2Pt crystals on Ge(110). J. Phys. Cond. Matt. 26, 442001 (2014).

    CAS  Google Scholar 

  26. 26

    D'Acapito, F. et al. Evidence for germanene growth on epitaxial hexagonal (h)-AlN on Ag(111). J. Phys. Cond. Matt. 28, 045002 (2016).

    CAS  Google Scholar 

  27. 27

    Zhu, F. F. et al. Epitaxial growth of two-dimensional stanene. Nat. Mater. 14, 1020 (2015).

    CAS  Google Scholar 

  28. 28

    Mannix, A. J. et al. Synthesis of borophenes: anisotropic, two-dimensional boron polymorphs. Science 350, 1513 (2015).

    CAS  Google Scholar 

  29. 29

    Feng, B. et al. Experimental realization of two-dimensional boron sheets. Nat. Chem. 8, 563–568 (2016).

    CAS  Google Scholar 

  30. 30

    Zhang, J. L. et al. Epitaxial growth of single layer blue phosphorus: a new phase of two-dimensional phosphorus. Nano Lett. 16, 4903–4908 (2016).

    CAS  Google Scholar 

  31. 31

    Bianco, E. et al. Stability and exfoliation of germanane: a germanium graphane analogue. ACS Nano 7, 4414 (2013).

    CAS  Google Scholar 

  32. 32

    Jiang, S., Arguilla, M. Q., Cultrara, N. D. & Goldberger, J. E. Covalently-controlled properties by design in group IV graphane analogues. Acc. Chem. Res. 48, 144 (2015).

    CAS  Google Scholar 

  33. 33

    Wohler, F. Ueber verbindungen des siliciums mit sauerstoff und wasserstoff. Liebigs Ann. Chem. 127, 257 (1863).

    Google Scholar 

  34. 34

    Jiang, S. et al. Improving the stability and optical properties of germanane via one-step covalent methyl-termination. Nat. Commun. 5, 3389 (2014).

    Google Scholar 

  35. 35

    Nakano, H. et al. Preparation of alkyl-modified silicon nanosheets by hydrosilylation of layered polysilane (Si6H6). J. Am. Chem. Soc. 134, 5452 (2012).

    CAS  Google Scholar 

  36. 36

    Liang, X. H., Zhang, Q. H., Lay, M. D. & Stickney, J. L. Growth of Ge nanofilms using electrochemical atomic layer deposition, with a “bait and switch” surface-limited reaction. J. Am. Chem. Soc. 133, 8199 (2011).

    CAS  Google Scholar 

  37. 37

    Qiu, J. et al. From silicene to half-silicane by hydrogenation. ACS Nano 9, 11192 (2015).

    CAS  Google Scholar 

  38. 38

    Yu, H. et al. Scanning tunneling microscopy of ethylated Si(111) surfaces prepared by a chlorination/alkylation process. J. Phys. Chem. B 110, 23898 (2006).

    CAS  Google Scholar 

  39. 39

    van de Walle, C. G. & Northrup, J. E. First-principles investigation of visible light emission from silicon-based materials. Phys. Rev. Lett. 70, 1116 (1993).

    CAS  Google Scholar 

  40. 40

    Xu, Y., Tang, P. Z. & Zhang, S. C. Large-gap quantum spin Hall states in decorated stanene grown on a substrate. Phys. Rev. B 92, 081112 (2015).

    Google Scholar 

  41. 41

    Chiappe, D. et al. Two-dimensional Si nanosheets with local hexagonal structure on a MoS2 surface. Adv. Mater. 26, 2096 (2014).

    CAS  Google Scholar 

  42. 42

    Zhang, L. et al. Structural and electronic properties of germanene on MoS2 . Phys. Rev. Lett. 116, 256804 (2016).

    CAS  Google Scholar 

  43. 43

    Molle, A. et al. Hindering the oxidation of silicene with non-reactive encapsulation. Adv. Funct. Mater. 23, 4340 (2013).

    CAS  Google Scholar 

  44. 44

    Tao, L. et al. Silicene field-effect transistors operating at room temperature. Nat. Nanotech. 10, 227 (2015).

    CAS  Google Scholar 

  45. 45

    Ezawa, M. Valley-polarized metals and quantum anomalous Hall effect in silicene. Phys. Rev. Lett. 109, 055502 (2012).

    Google Scholar 

  46. 46

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

    CAS  Google Scholar 

  47. 47

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

    Google Scholar 

  48. 48

    Si, C. et al. Functionalized germanene as a prototype of large-gap two-dimensional topological insulators. Phys. Rev. B 89, 115429 (2014).

    Google Scholar 

  49. 49

    Tang, P. Z. et al. Stable two-dimensional dumbbell stanene: a quantum spin Hall insulator. Phys. Rev. B 90, 121408(R) (2014).

    Google Scholar 

  50. 50

    Ezawa, M. J. Monolayer topological insulators: silicene, germanene, and stanene. Phys. Soc. Jpn 84, 121003 (2015).

    Google Scholar 

  51. 51

    Ezawa, M. Spin valleytronics in silicene: quantum spin Hall-quantum anomalous Hall insulators and single-valley semimetals. Phys. Rev. B 87, 155415 (2013).

    Google Scholar 

  52. 52

    Wang, J., Xu, Y. & Zhang, S. C. Two-dimensional time-reversal-invariant topological superconductivity in a doped quantum spin-Hall insulator. Phys. Rev. B 90, 054503 (2014).

    Google Scholar 

  53. 53

    Ezawa, M. Quantized conductance and field-effect topological quantum transistor in silicene nanoribbons. Appl. Phys. Lett. 102, 172103 (2013).

    Google Scholar 

  54. 54

    Vandenberghe, W. G. & Fischetti, M. V. Calculation of room temperature conductivity and mobility in tin-based topological insulator nanoribbons. J. Appl. Phys. 116, 173707 (2014).

    Google Scholar 

  55. 55

    Xu, Y., Gan, Z. X. & Zhang, S. C. Enhanced thermoelectric performance and anomalous Seebeck effects in topological insulators. Phys. Rev. Lett. 112, 226801 (2014).

    Google Scholar 

  56. 56

    Rachel, S. & Ezawa, M. Giant magnetoresistance and perfect spin filter in silicene, germanene, and stanene. Phys. Rev. B 89, 195303 (2014).

    Google Scholar 

  57. 57

    Wu, S. C., Shan, G. C. & Yan, B. H. Prediction of near-room-temperature quantum anomalous Hall effect on honeycomb materials. Phys. Rev. Lett. 113, 256401 (2014).

    Google Scholar 

  58. 58

    Wintterlin, J. & Bocquet, M. L. Graphene on metal surfaces. Surf. Sci. 603, 1841 (2009).

    CAS  Google Scholar 

  59. 59

    Scalise, E. et al. Vibrational properties of silicene and germanene. Nano Res. 6, 19 (2013).

    CAS  Google Scholar 

Download references

Acknowledgements

We thank C. Grazianetti, E. Cinquanta, L. Tao, M. Fanciulli, V.V. Afanas'ev, A. Stesmans, W. Vandenberghe, M. Fischetti, A. Dimoulas, D. Tsoutsou, C. Pirri and M. Ezawa for fruitful discussions. We also thank J. Wozniak of UT-Austin TACC Center for the renderings of Fig. 3. A.M. is partially supported by the National Research Council of Italy (CNR) under the joint lab project 'SFET' (2014 call). J.G. acknowledges partial support from the Center for Emergent Materials: an NSF MRSEC under award number DMR-1420451, partial support from NSF EFRI-1433467, and the Camille and Henry Dreyfus Foundation. M.H acknowledges financial support from the KU Leuven Research Funds, project GOA/13/011. A.M. and M.H. also acknowledge partial financial support from the EU-FP7 FET-Open grant no. 270749 ('2D-Nanolattices' project). Y.X. acknowledges support from Tsinghua University Initiative Scientific Research Program and the National Thousand-Young-Talents Program. S.C.Z. is supported by the Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, under contract DE-AC02-76SF00515 and by FAME, one of six centres of STARnet, a Semiconductor Research Corporation programme sponsored by MARCO and DARPA. D.A acknowledges support from the Army Research Office (ARO), the Presidential Early Career Award for Engineers and Scientists (PECASE), and the Gordon and Betty Moore Foundation.

Author information

Affiliations

Authors

Corresponding authors

Correspondence to Alessandro Molle or Deji Akinwande.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Molle, A., Goldberger, J., Houssa, M. et al. Buckled two-dimensional Xene sheets. Nature Mater 16, 163–169 (2017). https://doi.org/10.1038/nmat4802

Download citation

Further reading

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing