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Fast and Sensitive Colloidal Quantum Dot Mid-Wave Infrared Photodetectors
Matthew M Ackerman1, Xin Tang1, Philippe Guyot-Sionnest1
1James Franck Institute , The University of Chicago , 929 E. 57th Street , Chicago , Illinois 60637 , United States.
ACS Nano
|July 6, 2018
Summary
Colloidal quantum dot photodetectors offer a cost-effective solution for mid-wave infrared imaging. Enhancements in device architecture and chemical treatment significantly boosted sensitivity and efficiency for these infrared detectors.
Area of Science:
- Materials Science
- Nanotechnology
- Optoelectronics
Background:
- Colloidal quantum dots (CQDs) offer tunable band gaps for mid-wave infrared (MWIR) detection, presenting a cost-effective alternative to traditional photodetectors like HgCdTe (MCT) and InSb.
- Previous photoconductive HgTe CQD devices showed promise but were limited in speed and sensitivity.
- A recent proof-of-concept HgTe photovoltaic (PV) detector achieved background-limited performance at cryogenic temperatures.
Purpose of the Study:
- To improve the sensitivity and external quantum efficiency of HgTe CQD photodetectors for MWIR applications.
- To explore the potential of modified PV device architectures and chemical treatments for enhanced photodetector performance.
- To achieve performance comparable to commercial photodetectors using solution-processed CQDs.
Main Methods:
- Fabrication of modified HgTe CQD photovoltaic (PV) device architectures.
- Implementation of a solid-state cation exchange method for chemical interface modification.
- Integration of a thin-film interference structure with an optical spacer.
Main Results:
- Achieved up to a 2-order of magnitude improvement in HgTe CQD photodetector sensitivity.
- Demonstrated an order of magnitude increase in external quantum efficiency at room temperature due to cation exchange.
- Reported a sensitivity of 10^9 Jones at 230 K with a 4-5 μm cutoff wavelength, comparable to commercial devices.
- Attained near-unity internal quantum efficiency at reduced operating temperatures using the interference structure.
Conclusions:
- Modified PV device architectures and chemical treatments significantly enhance HgTe CQD photodetector performance.
- Solution-processed HgTe CQD photodetectors show potential for cost-effective MWIR detection.
- These advancements pave the way for broader applications in research, military defense, and beyond.
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