Colloidal quantum dots for thermal infrared sensing and imaging

Hafiz, Shihab Bin; Scimeca, Michael R.; Sahu, Ayaskanta; Ko, Dong Kyun

doi:10.1186/s40580-019-0178-1

Cited by 91 publications

(76 citation statements)

References 79 publications

(150 reference statements)

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“…In the quest for an alternative technology, a large effort has been dedicated to IR nanocrystals (NCs) 1 . Progresses on both material growth 2 – 6 and device design 7 transformed HgTe NCs into a versatile platform for IR optoelectronics 8 . Key developments include on-chip integration 9 , coupling to resonators to achieve strongly-absorbing devices 10 – 14 and hybridization to read out circuits to design focal plane arrays operating in the short-wave 15 , 16 and mid-wave IR 17 , 18 .…”

Section: Introductionmentioning

confidence: 99%

Infrared photoconduction at the diffusion length limit in HgTe nanocrystal arrays

et al. 2021

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Narrow band gap nanocrystals offer an interesting platform for alternative design of low-cost infrared sensors. It has been demonstrated that transport in HgTe nanocrystal arrays occurs between strongly-coupled islands of nanocrystals in which charges are partly delocalized. This, combined with the scaling of the noise with the active volume of the film, make case for device size reduction. Here, with two steps of optical lithography we design a nanotrench which effective channel length corresponds to 5–10 nanocrystals, matching the carrier diffusion length. We demonstrate responsivity as high as 1 kA W−1, which is 105 times higher than for conventional µm-scale channel length. In this work the associated specific detectivity exceeds 1012 Jones for 2.5 µm peak detection under 1 V at 200 K and 1 kHz, while the time response is as short as 20 µs, making this performance the highest reported for HgTe NC-based extended short-wave infrared detection.

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Section: Introductionmentioning

confidence: 99%

Infrared photoconduction at the diffusion length limit in HgTe nanocrystal arrays

et al. 2021

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“…In such application the confinement-induced renormalization of the band gap corresponds to a few tens of percent. Over the past decade, infrared optoelectronics 2 have also generated interest with applications such as solar cells 3,4 and low-cost infrared (IR) sensors 5,6,7,8,9 including focal plane arrays. 10,11,12 For these IR applications, narrow band gap materials such as lead and mercury chalcogenides are used, and the relative change of the band gap resulting from confinement can be even more important.…”

Section: Introductionmentioning

confidence: 99%

The Strong Confinement Regime in HgTe Two-Dimensional Nanoplatelets

Moghaddam

Gréboval

et al. 2020

J. Phys. Chem. C

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The confinement in colloidal HgTe nanocrystals enables this material to be promising for colloidal optoelectronics over a wide range of energies, from the THz spectral range up to the visible region. Herein, by using a combination of high energy absorption HgTe nanoplatelets and low energy absorption HgTe nanocrystals, we probe optical transmission of HgTe nanoparticles over the 0.26-1.8 eV range, from 0 K to 300 K temperatures and under simultaneous pressure, up to 4 GPa. While the pressure dependence of nanoplatelets follows the one observed for bulk and nanocrystals, the temperature dependence dramatically differs for nanoplatelets. The modeling of the electronic energy dispersion using up to 14-band k.p formalism suggests that the second conduction band and higher bands of HgTe play a vital role to describe and explain the HgTe nanoparticle spectroscopies.

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“…The electrical and optical properties of QDs can be tuned by controlling the size of strong quantum confinement effect [ 10 ]. Among the many applications of QDs, short-wave IR (SWIR) photodetectors are widely used in bio-imaging, security, face recognition, food safety inspection, and optical communications [ 11 – 15 ]. The technological advancement of SWIR photodetectors is not only attractive for these diverse applications, but also for the commercialization of technologies that are safe for human eyes.…”

Section: Introductionmentioning

confidence: 99%

Air-stable and ultrasensitive solution-cast SWIR photodetectors utilizing modified core/shell colloidal quantum dots

et al. 2020

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InGaAs-based photodetectors have been generally used for detection in the shortwave infrared (SWIR) region. However, the epitaxial process used to grow these materials is expensive; therefore, InGaAs-based photodetectors are limited to space exploration and military applications. Many researchers have expended considerable efforts to address the problem of SWIR photodetector development using lead sulfide (PbS) quantum dots (QDs). Along with their cost-efficient solution processability and flexible substrate compatibility, PbS QDs are highly interesting for the quantum-size-effect tunability of their bandgaps, spectral sensitivities, and wide absorption ranges. However, the performance of PbS QD-based SWIR photodetectors is limited owing to inefficient carrier transfer and low photo and thermal stabilities. In this study, a simple method is proposed to overcome these problems by incorporating CdS in PbS QD shells to provide efficient carrier transfer and enhance the long-term stability of SWIR photodetectors against oxidation. The SWIR photodetectors fabricated using thick-shell PbS/CdS QDs exhibited a high on/off (light/dark) ratio of 11.25 and a high detectivity of 4.0 × 10 12 Jones, which represents a greater than 10 times improvement in these properties relative to those of PbS QDs. Moreover, the lifetimes of thick-shell PbS/CdS QD-based SWIR photodetectors were significantly improved owing to the self-passivation of QD surfaces.

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Colloidal quantum dots for thermal infrared sensing and imaging

Cited by 91 publications

References 79 publications

Infrared photoconduction at the diffusion length limit in HgTe nanocrystal arrays

Infrared photoconduction at the diffusion length limit in HgTe nanocrystal arrays

The Strong Confinement Regime in HgTe Two-Dimensional Nanoplatelets

Air-stable and ultrasensitive solution-cast SWIR photodetectors utilizing modified core/shell colloidal quantum dots

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