Millimetre-long transport of photogenerated carriers in topological insulators

Yasen Hou, Rui Wang, Rui Xiao, Luke McClintock, Henry Clark Travaglini, John Paulus Francia, Harry Fetsch, Onur Erten, Sergey Y. Savrasov, Baigeng Wang, Antonio Rossi, Inna Vishik, Eli Rotenberg, Dong Yu

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


Excitons are spin integer particles that are predicted to condense into a coherent quantum state at sufficiently low temperature. Here by using photocurrent imaging we report experimental evidence of formation and efficient transport of non-equilibrium excitons in Bi2-xSbxSe3 nanoribbons. The photocurrent distributions are independent of electric field, indicating that photoexcited electrons and holes form excitons. Remarkably, these excitons can transport over hundreds of micrometers along the topological insulator (TI) nanoribbons before recombination at up to 40 K. The macroscopic transport distance, combined with short carrier lifetime obtained from transient photocurrent measurements, indicates an exciton diffusion coefficient at least 36 m2 s−1, which corresponds to a mobility of 6 × 104 m2 V−1 s−1 at 7 K and is four order of magnitude higher than the value reported for free carriers in TIs. The observation of highly dissipationless exciton transport implies the formation of superfluid-like exciton condensate at the surface of TIs.

Original languageEnglish (US)
Article number5723
JournalNature communications
Issue number1
StatePublished - Dec 1 2019

ASJC Scopus subject areas

  • Chemistry(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • General
  • Physics and Astronomy(all)


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