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  • Decoupling of Photocurrent and Dark Current for Extraordinary Detectivity in Uncooled Middle-Wavelength Infrared Nanohybrid Photodetectors

This content will become publicly available on March 11, 2026

Title: Decoupling of Photocurrent and Dark Current for Extraordinary Detectivity in Uncooled Middle-Wavelength Infrared Nanohybrid Photodetectors
Nanohybrids of graphene and colloidal semiconductor quantum dots (QDs/Gr) provide a promising quantum sensing scheme for photodetection. Despite exciting progress made in QDs/Gr photodetectors in broadband from ultraviolet to short-wave infrared, the device performance is limited in middle-wave infrared (MWIR) detection. A fundamental question arises as to whether the thermal noiseinduced dark current and hence poor signal-to-noise ratio in conventional uncooled MWIR photodetectors persist in QDs/ Gr nanohybrids. Herein, we investigated noise, responsivity (R*), and specific detectivity (D*) in HgTe QDs/Gr nanohybrids, revealing that the noise and R* are decoupled in nanohybrids and each can be optimized independently toward its theoretical limit. Specifically, the noise in the QDs/Gr nanohybrids is dominated by that of graphene with a negligible effect from the dark current in HgTe QDs and can be optimized to its intrinsic limit by removing charge doping of adsorbed polar molecules on graphene. Furthermore, the R* is proportional to the photoconductive gain enabled by the strong quantum confinement in QDs and Gr. Achieving high gain in the MWIR spectrum, however, is challenging and requires elimination of charge traps primarily from the surface states of the narrow-bandgap semiconductor HgTe QDs. Using grain-rotation-induced grain-coalescence growth of single-layer and core/shell HgTe QDs, we show the that HgTe QDs surface states caused by Te deficiency can be dramatically suppressed, resulting in high gain up to 4.0 × 107 in the MWIR spectrum. The optimized noise and R* have led to high uncooled MWIR D* up to 2.4 × 1011 Jones, making nanohybrids promising to surpass the fundamental dark-current limit in conventional photodetectors.  more » « less
Award ID(s):
2314401 2413044 2412221
PAR ID:
10599057
Author(s) / Creator(s):
; ; ; ; ; ; ; ;
Publisher / Repository:
ACS
Date Published:
Journal Name:
ACS Nano
Volume:
19
Issue:
9
ISSN:
1936-0851
Page Range / eLocation ID:
8520 to 8538
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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