Title: Interlayer exciton optoelectronics in a 2D heterostructure p–n junction

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 MoSe ₂–WSe ₂ 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. Lastly, these results lay the foundation for exploiting the interlayermore » exciton in future 2D heterostructure optoelectronic devices.« less

Authors:

Ross, Jason S. ^[1]; Rivera, Pasqual ^[1]; Schaibley, John ^[1]; Lee-Wong, Eric ^[1]; Yu, Hongyi ^[2]; Taniguchi, Takashi ^[3]; Watanabe, Kenji ^[3]; Yan, Jiaqiang ^[4]; Mandrus, David ^[4]; Cobden, David ^[1]; Yao, Wang ^[2]; Xu, Xiaodong ^[1]

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+ Show Author Affiliations

1. Univ. of Washington, Seattle, WA (United States)
2. Univ. of Hong Kong, Hong Kong (China)
3. National Institute for Materials Science, Ibaraki (Japan)
4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Publication Date:

2016-12-22

Research Org.:

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1350948

Grant/Contract Number:  

AC05-00OR22725

Resource Type:

Journal Article: Accepted Manuscript

Journal Name:

Nano Letters

Additional Journal Information:

Journal Volume: 17; Journal Issue: 2; Journal ID: ISSN 1530-6984

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; interlayer exciton; optoelectronics; p−n junction; transition metal dichalcogenides; van der Waals heterostructure