Abstract
The interplay of Dirac physics and induced superconductivity at the interface of a 3D topological insulator (TI) with an s-wave superconductor (S) provides a new platform for topologically protected quantum computation based on elusive Majorana modes. To employ such S–TI hybrid devices in future topological quantum computation architectures, a process is required that allows for device fabrication under ultrahigh vacuum conditions. Here, we report on the selective area growth of (Bi,Sb)2Te3 TI thin films and stencil lithography of superconductive Nb for a full in situ fabrication of S–TI hybrid devices via molecular-beam epitaxy. A dielectric capping layer was deposited as a final step to protect the delicate surfaces of the S–TI hybrids at ambient conditions. Transport experiments in as-prepared Josephson junctions show highly transparent S–TI interfaces and a missing first Shapiro step, which indicates the presence of Majorana bound states. To move from single junctions towards complex circuitry for future topological quantum computation architectures, we monolithically integrated two aligned hardmasks to the substrate prior to growth. The presented process provides new possibilities to deliberately combine delicate quantum materials in situ at the nanoscale.
This is a preview of subscription content, access via your institution
Access options
Access Nature and 54 other Nature Portfolio journals
Get Nature+, our best-value online-access subscription
$29.99 / 30 days
cancel any time
Subscribe to this journal
Receive 12 print issues and online access
$259.00 per year
only $21.58 per issue
Buy this article
- Purchase on Springer Link
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
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
König, M. et al. Quantum spin Hall insulator state in HgTe quantum wells. Science 318, 766–770 (2007).
Fu, L., Kane, C. L. & Mele, E. J. Topological insulators in three dimensions. Phys. Rev. Lett. 98, 106803 (2007).
Hsieh, D. et al. Observation of unconventional quantum spin textures in topological insulators. Science 323, 919–922 (2009).
Zhang, H. et al. Topological insulators in Bi2Se3, Bi2Te3 and Sb2Te3 with a single Dirac cone on the surface. Nat. Phys. 5, 438–442 (2009).
Fu, L. & Kane, C. L. Superconducting proximity effect and Majorana fermions at the surface of a topological insulator. Phys. Rev. Lett. 100, 096407 (2008).
Cook, A. & Franz, M. Majorana fermions in a topological-insulator nanowire proximity-coupled to an s-wave superconductor. Phys. Rev. B. 84, 201105 (2011).
Cook, A., Vazifeh, M. M. & Franz, M. Stability of Majorana fermions in proximity-coupled topological insulator nanowires. Phys. Rev. B 86, 155431 (2012).
Manousakis, J., Altland, A., Bagrets, D., Egger, R. & Ando, Y. Majorana qubits in a topological insulator nanoribbon architecture. Phys. Rev. B 95, 165424 (2017).
Kitaev, A. Y. Unpaired Majorana fermions in quantum wires. Phys. Usp. 44, 131–136 (2001).
Alicea, J. Majorana fermions in a tunable semiconductor device. Phys. Rev. B 81, 125318 (2010).
Kitaev, A. Y. Fault-tolerant quantum computation by anyons. Ann. Phys. 303, 2–30 (2003).
Aasen, D. et al. Milestones toward Majorana-based quantum computing. Phys. Rev. X 6, 031016 (2016).
Litinski, D., Kesselring, M. S., Eisert, J. & von Oppen, F. Combining topological hardware and topological software: color-code quantum computing with topological superconductor. Netw. Phys. Rev. X 7, 031048 (2017).
Alicea, J., Oreg, Y., Refael, G., Von Oppen, F. & Fisher, M. P. Non-Abelian statistics and topological quantum information processing in 1D wire networks. Nat. Phys. 7, 412–417 (2011).
Hyart, T. et al. Flux-controlled quantum computation with Majorana fermions. Phys. Rev. B 88, 035121 (2013).
van Heck, B., Akhmerov, A. R., Hassler, F., Burrello, M. & Beenakker, C. W. J. Coulomb-assisted braiding of Majorana fermions in a Josephson junction array. New J. Phys. 14, 035019 (2012).
Josephson, B. D. Possible new effects in superconductive tunnelling. Phys. Lett. 1, 251–253 (1962).
Golubov, A. A., Kupriyanov, M. Y. & Il’ichev, E. The current-phase relation in Josephson junctions. Rev. Mod. Phys. 76, 411–469 (2004).
Domínguez, F. et al. Josephson junction dynamics in the presence of 2π and 4π-periodic supercurrents. Phys. Rev. B 95, 195430 (2017).
Fu, L. Electron teleportation via Majorana bound states in a mesoscopic superconductor. Phys. Rev. Lett. 104, 056402 (2010).
Le Calvez, K. et al. Joule overheating poisons the fractional ac Josephson effect in topological Josephson junctions. Comm. Phys. 2, 4 (2019).
Bocquillon, E. et al. Gapless Andreev bound states in the quantum spin Hall insulator HgTe. Nat. Nanotechnol. 12, 137–143 (2017).
Wiedenmann, J. et al. 4π-periodic Josephson supercurrent in HgTe-based topological Josephson junctions. Nat. Com. 7, 10303 (2016).
Li, C. et al. 4π-periodic Andreev bound states in a Dirac semimetal. Nat. Mater. 17, 875–880 (2018).
Dominguez, F., Hassler, F. & Platero, G. Dynamical detection of Majorana fermions in current-biased nanowires. Phys. Rev. B 86, 140503 (2012).
Ngabonziza, P. et al. In situ spectroscopy of intrinsic Bi2Te3 topological insulator thin films and impact of extrinsic defects. Phys. Rev. B 92, 035405 (2015).
Thomas, C. R. et al. Surface oxidation of Bi2(Te,Se)3 topological insulators depends on cleavage accuracy. Chem. Mater. 28, 35–39 (2016).
Benia, H. M., Lin, C., Kern, K. & Ast, C. R. Reactive chemical doping of the Bi2Se3 topological insulator. Phys. Rev. Lett. 107, 177602 (2011).
Lang, M. R. et al. Revelation of topological surface states in Bi2Se3 thin films by in situ Al passivation. ACS Nano 6, 295–302 (2012).
Ngabonziza, P. et al. Gate-tunable transport properties of in situ capped Bi2Te3 topological insulator thin films. Adv. Electron Mater. 2, 1600157 (2016).
Schüffelgen, P. et al. Signatures of induced superconductivity in AlOx-capped topological heterostructures. Solid State Electron. 155, 111–116 (2019).
Kampmeier, J. et al. Selective area growth of Bi2Te3 and Sb2Te3 topological insulator thin films. J. Cryst. Growth 443, 38–42 (2016).
Christian, W. et al. Phase-coherent transport in selectively grown topological insulator nanodots. Nanotechnology 30, 055201 (2019).
Bohg, A. & Gaind, A. K. Influence of film stress and thermal oxidation on the generation of dislocations in silicon. Appl. Phys. Lett. 33, 895–897 (1978).
Moors, K. et al. Magnetotransport signatures of three-dimensional topological insulator nanostructures. Phys. Rev. B 97, 245429 (2018).
Ghatak, S. et al. Anomalous Fraunhofer patterns in gated Josephson junctions based on the bulk-insulating topological insulator BiSbTeSe2. Nano Lett. 18, 5124–5131 (2018).
van Woerkom, D. J., Geresdi, A. & Kouwenhoven, L. P. One minute parity lifetime of a NbTiN Cooper-pair transistor. Nat. Phys. 11, 547–550 (2015).
Schüffelgen, P. et al. Stencil lithography of superconducting contacts on MBE-grown topological insulator thin films. J. Cryst. Growth 477, 183–187 (2017).
Desplanque, L., Bucamp, A., Troadec, D., Patriarche, G. & Wallart, X. In-plane InSb nanowires grown by selective area molecular-beam epitaxy on semi-insulating substrate. Nanotechnology 29, 305705 (2018).
Aseev, P. et al. Selectivity map for molecular-beam epitaxy of advanced III–V quantum nanowire networks. Nano Lett. 19, 218–227 (2019).
Krizek, F. et al. Field effect enhancement in buffered quantum nanowire networks. Phys. Rev. Mat. 2, 093401 (2018).
Kampmeier, J. et al. Suppressing twin domains in molecular beam epitaxy grown Bi2Te3 topological insulator thin films. Cryst. Growth Des. 15, 390–394 (2016).
Kellner, J. et al. Tuning the Dirac point to the Fermi level in the ternary topological insulator (Bi1–xSbx)2Te3. Appl. Phys. Lett. 107, 251603 (2015).
Kovács, A., Schierholz, R. & Tillmann, K. FEI Titan G2 80-200 CREWLEY. J. Large-Scale Res. Facil. 2, A43 (2016).
Acknowledgements
A. Braginski and F. Hassler are acknowledged for enlightening discussions. M. Geitner and K.-H. Deussen are acknowledged for the deposition of Si3N4 and SiO2 layers. The authors thank G. Nagda and C. Beale for proofreading the manuscript. This work is supported by the German Science Foundation (DFG) under the priority program SPP1666 “Topological Insulators”, as well as by the Helmholtz Association via the “Virtual Institute for Topological Insulators” and the IVF project “Scalable Solid State Quantum Computing”.
Author information
Authors and Affiliations
Contributions
P.S., D.R., T.W.S., M.S. and E.B. fabricated the substrates in the clean room. S.T. performed electron-beam lithography. P.S., M.S., A.R.J., S.S., M.W. and G.M. grew the TI thin films via MBE. B.B. grew the superconducting Nb. U.P. capped the sample with stoichiometric Al2O3. P.S., D.R., C.L. and T.W.S. performed the electrical transport measurements on Josephson devices. D.R. and J.K. investigated the magnetotransport on Hall bars. T.G. removed the stencil mask via mechanical polishing. L.K., D.M. and M.L. prepared the focused ion-beam lamellae and performed high-resolution scanning transmission electron microscopy measurements. A.B. and A.A.G. carried out the Eilenberger and Usadel fitting. P.S., D.R. and A.B. wrote the paper with contributions from all the co-authors. P.S. initiated the project, which was supervised by N.T., A.A.G., A.B., T.S. and D.G.
Corresponding author
Ethics declarations
Competing interests
The authors declare no competing interests.
Additional information
Peer review information: Nature Nanotechnology thanks Torsten Karzig and other, anonymous, reviewer(s) for their contribution to the peer review of this work.
Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Supplementary information
Supplementary Information
Supplementary Figs. 1–8 and Supplementary Table 1.
Rights and permissions
About this article
Cite this article
Schüffelgen, P., Rosenbach, D., Li, C. et al. Selective area growth and stencil lithography for in situ fabricated quantum devices. Nat. Nanotechnol. 14, 825–831 (2019). https://doi.org/10.1038/s41565-019-0506-y
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1038/s41565-019-0506-y
This article is cited by
-
Interference, diffraction, and diode effects in superconducting array based on bismuth antimony telluride topological insulator
Communications Physics (2023)
-
Nonreciprocal charge transport in topological superconductor candidate Bi2Te3/PdTe2 heterostructure
npj Quantum Materials (2022)
-
Proximity-induced superconductivity in (Bi1−xSbx)2Te3 topological-insulator nanowires
Communications Materials (2022)
-
Microwave spectroscopy of Andreev states in InAs nanowire-based hybrid junctions using a flip-chip layout
Communications Physics (2022)
-
Fusion of Majorana bound states with mini-gate control in two-dimensional systems
Nature Communications (2022)