Nanophotonics (Aug 2022)

Waveguide-integrated mid-IR photodetector and all-optical modulator based on interlayer excitons absorption in a WS2/HfS2 heterostructure

  • Edelstein Shahar,
  • Indukuri S. R. K. Chaitanya,
  • Mazurski Noa,
  • Levy Uriel

DOI
https://doi.org/10.1515/nanoph-2022-0203
Journal volume & issue
Vol. 11, no. 19
pp. 4337 – 4345

Abstract

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Novel 2D van der Waals semiconductors facilitate the formation of heterostructures and thus support bandgap engineering for atomically thin modern photonic applications. When these heterostructures form a type II band structure, interlayer excitons (ILEs) are formed as a result of the ultrafast charge transfer between the layers. Here, we present for the first time a waveguide-coupled, mid-IR photodetector and modulator based on the ILE absorption. The device consists of a heterostructure of a single layer of tungsten disulfide (WS2) and a few layers of hafnium disulfide (HfS2) integrated to a silicon waveguide on a sapphire substrate. We measure broadband mid-IR photodetection (3.8–5.5 µm) with responsivity in the order of tens of µA/W and with no significant effect on the waveguide’s transmission. Additionally, we demonstrate waveguide-integrated, mid-IR, all-optical modulation by controlling the ILE population with the interband transition of the individual layers of the heterostructure.

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