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.

  • Letter
  • Published:

Hard gap in epitaxial semiconductor–superconductor nanowires

Nature Nanotechnology volume 10, pages 232–236 (2015)Cite this article

Subjects

Abstract

Many present and future applications of superconductivity would benefit from electrostatic control of carrier density and tunnelling rates, the hallmark of semiconductor devices. One particularly exciting application is the realization of topological superconductivity1 as a basis for quantum information processing2,3. Proposals in this direction based on the proximity effect in semiconductor nanowires are appealing because the key ingredients are currently in hand4,5. However, previous instances of proximitized semiconductors show significant tunnelling conductance below the superconducting gap, suggesting a continuum of subgap states—a situation that nullifies topological protection6,7. Here, we report a hard superconducting gap induced by the proximity effect in a semiconductor, using epitaxial InAs–Al semiconductor–superconductor nanowires. The hard gap, together with favourable material properties and gate-tunability, makes this new hybrid system attractive for a number of applications, as well as fundamental studies of mesoscopic superconductivity.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Epitaxial full-shell device and hard induced gap.
Figure 2: Gate dependence of conductance of full-shell device.
Figure 3: Comparing quantum point contact and quantum dot devices.
Figure 4: Magnetic field and temperature dependence of induced gaps.
Figure 5: Epitaxial half-shell device and gate-tunability of InAs core.

Similar content being viewed by others

References

  1. Kitaev, A. Y. Unpaired Majorana fermions in quantum wires. Phys. Usp. 44, 131–136 (2001).

    Article  Google Scholar 

  2. Nayak, C., Simon, S. H., Stern, A., Freedman, M. & Das Sarma, S. Non Abelian anyons and topological quantum computation. Rev. Mod. Phys. 80, 1083–1159 (2008).

    Article  CAS  Google Scholar 

  3. Alicea, J., Oreg, Y., Refael, G., von Oppen, F. & Fisher, M. P. A. Non-Abelian statistics and topological quantum information processing in 1D wire networks. Nature Phys. 7, 412–417 (2011).

    Article  CAS  Google Scholar 

  4. Lutchyn, R. M., Sau, J. D. & Das Sarma, S. Majorana fermions and a topological phase transition in semiconductor–superconductor heterostructures. Phys. Rev. Lett. 105, 077001 (2010).

    Article  Google Scholar 

  5. Oreg, Y., Refael, G. & von Oppen, F. Helical liquids and Majorana bound states in quantum wires. Phys. Rev. Lett. 105, 177002 (2010).

    Article  Google Scholar 

  6. Cheng, M., Lutchyn, R. M. & Das Sarma, S. Topological protection of Majorana qubits. Phys. Rev. B 85, 165124 (2012).

    Article  Google Scholar 

  7. Rainis, D. & Loss, D. Majorana qubit decoherence by quasiparticle poisoning. Phys. Rev. B 85, 174533 (2012).

    Article  Google Scholar 

  8. Mourik, V. et al. Signatures of Majorana fermions in hybrid superconductor–semiconductor nanowire devices. Science 336, 1003–1007 (2012).

    Article  CAS  Google Scholar 

  9. Das, A. et al. Zero-bias peaks and splitting in an Al–InAs nanowire topological superconductor as a signature of Majorana fermions. Nature Phys. 8, 887–895 (2012).

    Article  CAS  Google Scholar 

  10. Deng, M. T. et al. Anomalous zero-bias conductance peak in a Nb–InSb nanowire–Nb hybrid device. Nano Lett. 12, 6414–6419 (2012).

    Article  CAS  Google Scholar 

  11. Churchill, H. O. H. et al. Superconductor–nanowire devices from tunneling to the multichannel regime: Zero-bias oscillations and magnetoconductance crossover. Phys. Rev. B 87, 241401 (2013).

    Article  Google Scholar 

  12. Takei, S., Fregoso, B. M., Hui, H-Y., Lobos, A. M. & Das Sarma, S. Soft superconducting gap in semiconductor Majorana nanowires. Phys. Rev. Lett. 110, 186803 (2013).

    Article  Google Scholar 

  13. Krogstrup, P. et al. Junctions in axial III–V heterostructure nanowires obtained via an interchange of group III elements. Nano Lett. 9, 3689–3693 (2009).

    Article  CAS  Google Scholar 

  14. Krogstrup, P. et al. Epitaxy of semiconductor–superconductor nanowires. Nature Mater.http://dx.doi.org/10.1038/nmat4176 (2015).

  15. Chang, W., Manucharyan, V. E., Jespersen, T. S., Nygård, J. & Marcus, C. M. Tunneling spectroscopy of quasiparticle bound states in a spinful Josephson junction. Phys. Rev. Lett. 110, 217005 (2013).

    Article  CAS  Google Scholar 

  16. Finck, A. D. K., Van Harlingen, D. J., Mohseni, P. K., Jung, K. & Li, X. Anomalous modulation of a zero-bias peak in a hybrid nanowire–superconductor device. Phys. Rev. Lett. 110, 126406 (2013).

    Article  CAS  Google Scholar 

  17. Beenakker, C. W. J. Quantum transport in semiconductor–superconductor microjunctions. Phys. Rev. B 46, 12841–12844 (1992).

    Article  CAS  Google Scholar 

  18. Blonder, G. E., Tinkham, M. & Klapwijk, T. M. Transition from metallic to tunneling regimes in superconducting microconstrictions: Excess current, charge imbalance, and supercurrent conversion. Phys. Rev. B 25, 4515–4532 (1982).

    Article  CAS  Google Scholar 

  19. Chuang, S. et al. Ballistic InAs nanowire transistors. Nano Lett. 13, 555–558 (2013).

    Article  CAS  Google Scholar 

  20. Ford, A. C., Kumar, S. B., Kapadia, R., Guo, J. & Javey, A. Observation of degenerate one-dimensional sub-bands in cylindrical InAs nanowires. Nano Lett. 12, 1340–1343 (2012).

    Article  CAS  Google Scholar 

  21. Yu, L. Bound state in superconductors with paramagnetic impurities. Acta Phys. Sin. 21, 75–91 (1965).

    CAS  Google Scholar 

  22. Shiba, H. Classical spins in superconductors. Prog. Theor. Phys. 40, 435–451 (1968).

    Article  Google Scholar 

  23. Rusinov, A. I. Theory of gapless superconductivity in alloys containing paramagnetic impurities. Sov. Phys. JETP 29, 1101–1106 (1969).

    Google Scholar 

  24. Koerting, V., Andersen, B. M., Flensberg, K. & Paaske, J. Nonequilibrium transport via spin-induced subgap states in superconductor/quantum dot/normal metal cotunnel junctions. Phys Rev. B 82, 2451081–2451084 (2010).

    Article  Google Scholar 

  25. Deacon, R. S. et al. Tunneling spectroscopy of Andreev energy levels in a quantum dot coupled to a superconductor. Phys. Rev. Lett. 104, 076805 (2010).

    Article  CAS  Google Scholar 

  26. Lee, E. J. H. et al. Spin-resolved Andreev levels and parity crossings in hybrid superconductor–semiconductor nanostructures. Nature Nanotech. 9, 79–84 (2014).

    Article  CAS  Google Scholar 

  27. Dirks, T. et al. Transport through Andreev bound states in a graphene quantum dot. Nature Phys. 7, 386–390 (2011).

    Article  CAS  Google Scholar 

  28. Pillet, J-D. et al. Andreev bound states in supercurrent-carrying carbon nanotubes revealed. Nature Phys. 6, 965–969 (2010).

    Article  CAS  Google Scholar 

  29. Meng, T., Florens, S. & Simon, P. Self-consistent description of Andreev bound states in Josephson quantum dot devices. Phys. Rev. B 79, 224521 (2009).

    Article  Google Scholar 

  30. Deacon, R. S. et al. Kondo-enhanced andreev transport in single self-assembled InAs quantum dots contacted with normal and superconducting leads. Phys. Rev. B 81, 121308 (2010).

    Article  Google Scholar 

  31. Vecino, E., Martín-Rodero, A. & Yeyati, A. L. Josephson current through a correlated quantum level: Andreev states and π junction behavior. Phys. Rev. B 68, 035105 (2003).

    Article  Google Scholar 

  32. Tinkham, M. Introduction to Superconductivity 2nd edn (Dover, 2004).

    Google Scholar 

  33. Wunnicke, O. Gate capacitance of back-gated nanowire field-effect transistors. Appl. Phys. Lett. 89, 083102 (2006).

    Article  Google Scholar 

  34. Doh, Y-J. et al. Tunable supercurrent through semiconductor nanowires. Science 309, 272–275 (2005).

    Article  CAS  Google Scholar 

  35. Jespersen, T. S., Polianski, M. L., Sørensen, C. B., Flensberg, K. & Nygård, J. Mesoscopic conductance fluctuations in InAs nanowire-based SNS junctions. New J. Phys. 11, 113025 (2009).

    Article  Google Scholar 

Download references

Acknowledgements

The authors thank E. Johnson for assistance with electron microscopy and K. Flensberg for discussions. This research was supported by Microsoft Project Q, the Danish National Research Foundation, the Carlsberg Foundation, the Villum Foundation, the Lundbeck Foundation and the European Commission.

Author information

Authors and Affiliations

  1. Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, Copenhagen, 2100, Denmark

    W. Chang, S. M. Albrecht, T. S. Jespersen, F. Kuemmeth, P. Krogstrup, J. Nygård & C. M. Marcus

  2. Department of Physics, Harvard University, Cambridge, 02138, Massachusetts, USA

    W. Chang

Authors
  1. W. Chang
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. S. M. Albrecht
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. T. S. Jespersen
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. F. Kuemmeth
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. P. Krogstrup
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. J. Nygård
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. C. M. Marcus
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

P.K., T.S.J. and J.N. developed the nanowire materials. W.C. and S.A. fabricated the devices and carried out the measurements with input from F.K., T.S.J. and C.M. All authors contributed to analysing and interpreting the data and to writing the manuscript.

Corresponding author

Correspondence to C. M. Marcus.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary information

Supplementary Information (PDF 3331 kb)

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Chang, W., Albrecht, S., Jespersen, T. et al. Hard gap in epitaxial semiconductor–superconductor nanowires. Nature Nanotech 10, 232–236 (2015). https://doi.org/10.1038/nnano.2014.306

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nnano.2014.306

This article is cited by

Search

Advanced 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