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Uncooled High Detectivity Mid-Infrared Photoconductor Using HgTe Quantum Dots and Nanoantennas
Augustin Caillas1, Philippe Guyot-Sionnest1
1James Franck Institute, The University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, United States.
ACS Nano
|March 11, 2024
Summary
This study demonstrates a metal/insulator/metal (MIM) structure that significantly boosts mid-infrared light absorption and performance in HgTe colloidal quantum dot (CQD) films. This nanoantenna approach enhances photodetector responsivity and detectivity for advanced infrared applications.
Area of Science:
- Materials Science
- Nanotechnology
- Optoelectronics
Background:
- Colloidal quantum dots (CQDs) offer tunable optoelectronic properties for infrared applications.
- Enhancing light absorption in thin CQD films is crucial for improving photodetector performance.
- Metal/insulator/metal (MIM) structures with nanoantennas can concentrate electromagnetic fields.
Purpose of the Study:
- To investigate the enhancement of mid-infrared absorption and photodetector performance in HgTe CQD films using MIM nanoantenna structures.
- To correlate optical absorption enhancements with photodetector responsivity and detectivity.
- To validate simulation results with experimental measurements.
Main Methods:
- Fabrication of a gold nanoantenna array on a sapphire substrate using electron beam lithography.
- Deposition of an 80 nm HgTe CQD film onto the nanoantenna structure.
- Optical characterization including absorption and photoluminescence spectroscopy.
- Electrical characterization of photodetector performance, including responsivity, gain, and detectivity.
- Electromagnetic simulations to understand field enhancement mechanisms.
Main Results:
- The MIM structure achieved a 23-fold enhancement in spatially averaged peak spectral absorption (60%) for the CQD film.
- Field intensity enhancement reached up to 1000-fold at the nanoantenna tips.
- A responsivity of 0.6 A/W and a photoconductive gain of 0.3 were achieved at 1 V bias.
- Spatially averaged peak detectivity was improved 15-fold, reaching 9 × 109 Jones.
- Photoluminescence was enhanced 16-fold, indicating potential Purcell enhancement.
Conclusions:
- Lithographically designed nanoantenna structures significantly improve the performance of mid-infrared CQD photoconductors.
- The MIM structure provides a viable platform for enhancing light-matter interactions in CQD films.
- Further performance gains are achievable by optimizing the overlap between optical enhancement and electrical collection areas.
