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We demonstrate a quantum ratchet detector, which is a high-resistance photovoltaic mid-infrared detector based on an engineered spatial arrangement of subbands. In photovoltaic quantum-well photodetectors, in which unidirectional photocurrent is generated by asymmetric quantum-well structures, maximization of device resistance by suppressing undesired electron transports is crucial for minimizing noise. A semi-quantitative guideline suggests the significance of spatial separation between wavefunctions for reducing the conductance from the ground state. Here, we employ a step quantum well made of a shallow floor and a deep well. Photoexcited electrons are quickly transferred to a separated location from the ground state through fast resonant tunneling and phonon scattering, and then they are allowed to flow in only one direction. This architecture is made possible by the use of a GaAs/AlGaAs material system, and it achieves a resistance as high as 6.0×104 Ωcm2 with a single-period structure. Combined with optical patch antennas for responsivity enhancement, we demonstrate a maximum background-limited specific detectivity of 6.8×1010 cmHz1/2/W at 6.4 μm, 77 K for normal incidence, and a background-limited-infrared-photodetector temperature of 98 K.

Rights:

• Creative Commons BY Attribution 4.0 International
  VC 2024 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/4.0/). https://doi.org/10.1063/5.0208399

Keyword: Photodetectors, Quantum wells, Optical antennas, Infrared

Date published: 2024-06-03

Publisher: AIP Publishing

Journal:

• Applied Physics Letters (ISSN: 00036951) vol. 124 issue. 23

Funding:

• Japan Society for the Promotion of Science JP22K18990
• Japan Society for the Promotion of Science JP23H01883
• Japan Society for the Promotion of Science JP24K01367

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

MDR DOI:

First published URL: https://doi.org/10.1063/5.0208399

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Updated at: 2024-06-11 12:30:23 +0900

Published on MDR: 2024-06-11 12:30:24 +0900