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Semiconductor heterojunctions are ubiquitous components of modern electronics. Their properties are determined crucially by the band alignment at the interface, which may exhibit straddling gap (type-I), staggered gap (type-II) or broken gap (type-III). While it is desirable to manually switch the band alignment type - each of which has their distinctive characteristics and applications - within a single active material, such an extraordinary device has never been realized. Here we demonstrate the electrically controllable transition between type-I and type-II alignment and characterize its optical and photocurrent signatures in MoSe2/WS2 heterobilayers. Intrinsic MoSe2/WS2 heterobilayers exhibit type-I band alignment with dominant intralayer exciton luminescence from the MoSe2 layer. Under a strong vertical electric field, however, the heterobilayer transitions to type-II band alignment and switches on strong interlayer exciton luminescence. Moreover, as the interlayer exciton state is turned on, the trapping of free carriers suppresses the interlayer photocurrent, resulting in highly nonlinear photocurrent-voltage characteristics. The precise electrical control of band alignment, interlayer excitons, and free carrier trapping established here heralds a new class of versatile optical and (opto)electronic devices composed of van der Waals heterostructures.

Rights:

• Creative Commons BY Attribution 4.0 International
  

Keyword: Semiconductor heterojunctions, band alignment, MoSe2/WS2

Date published: 2024-05-14

Publisher: Springer Science and Business Media LLC

Journal:

• Nature Communications (ISSN: 20411723) vol. 15 issue. 1 4075

Funding:

Manuscript type: Publisher's version (Version of record)

MDR DOI:

First published URL: https://doi.org/10.1038/s41467-024-48321-1

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Updated at: 2025-02-23 22:48:36 +0900

Published on MDR: 2025-02-23 22:48:36 +0900