Interlayer Exciton Optoelectronics in a 2D Heterostructure p-n Junction

Jason S. Ross, Pasqual Rivera, John Schaibley, Eric Lee-Wong, Hongyi Yu, Takashi Taniguchi, Kenji Watanabe, Jiaqiang Yan, David Mandrus, David Cobden, Wang Yao, Xiaodong Xu

Research output: Contribution to journalArticlepeer-review

189 Scopus citations

Abstract

Semiconductor heterostructures are backbones for solid-state-based optoelectronic devices. Recent advances in assembly techniques for van der Waals heterostructures have enabled the band engineering of semiconductor heterojunctions for atomically thin optoelectronic devices. In two-dimensional heterostructures with type II band alignment, interlayer excitons, where Coulomb bound electrons and holes are confined to opposite layers, have shown promising properties for novel excitonic devices, including a large binding energy, micron-scale in-plane drift-diffusion, and a long population and valley polarization lifetime. Here, we demonstrate interlayer exciton optoelectronics based on electrostatically defined lateral p-n junctions in a MoSe2-WSe2 heterobilayer. Applying a forward bias enables the first observation of electroluminescence from interlayer excitons. At zero bias, the p-n junction functions as a highly sensitive photodetector, where the wavelength-dependent photocurrent measurement allows the direct observation of resonant optical excitation of the interlayer exciton. The resulting photocurrent amplitude from the interlayer exciton is about 200 times smaller than the resonant excitation of intralayer exciton. This implies that the interlayer exciton oscillator strength is 2 orders of magnitude smaller than that of the intralayer exciton due to the spatial separation of electron and hole to the opposite layers. These results lay the foundation for exploiting the interlayer exciton in future 2D heterostructure optoelectronic devices.

Original languageEnglish (US)
Pages (from-to)638-643
Number of pages6
JournalNano Letters
Volume17
Issue number2
DOIs
StatePublished - Feb 8 2017
Externally publishedYes

Keywords

  • interlayer exciton
  • optoelectronics
  • p−n junction
  • transition metal dichalcogenides
  • van der Waals heterostructure

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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