Thermal Imaging with Plasmon Resonance Enhanced HgTe Colloidal Quantum Dot Photovoltaic Devices

Abstract

Thermal imaging in the midwave infrared plays an important role for numerous applications. The key functionality is imaging devices in the atmospheric window between 3 and 5 μm, where disturbance from fog, dust, and other atmospheric influence could be avoided. Here, we demonstrate sensitive thermal imaging with HgTe colloidal quantum dot (CQD) photovoltaic detectors by integrating the HgTe CQDs with plasmonic structures. The responsivity at 5 μm is enhanced 2- to 3-fold over a wide range of operating temperatures from 295 to 85 K. A detectivity of 4 × 10 Jones is achieved at cryogenic temperature. The noise equivalent temperature difference is 14 mK at an acquisition rate of 1 kHz for a 200 μm pixel. Thermal images are captured with a single-pixel scanning imaging system.

Towards Infrared Electronic Eyes: Flexible Colloidal Quantum Dot Photovoltaic Detectors Enhanced by Resonant Cavity

“…The solution was precipitated with excess acetone and stored in chlorobenzene or tetrachloroethylene. 400 nm HgTe CQDs film was then drop‐casted as the sensing material . Thicker film gave stronger absorption, but longer transport length which led to lower collection efficiency.…”

“…The photocurrent was first amplified with a transimpedance amplifier and then amplified by a voltage amplifier. The noise was measured using a spectrum analyzer as reported in prior work …”

HgTe Nanocrystal Inks for Extended Short‐Wave Infrared Detection

“…Recently, mid‐wave infrared photodiodes, with high photoresponse (up to 0.8 A W −1 ), have been proposed by Guyot–Sionnest's group. Part of this success is based on the use of plasmon resonance to enhance the absorption of thin nanocrystal films with thicknesses below the absorption depth . Yet, their 5 µm cut‐off wavelength means that these devices still need to be cooled down to cryogenic temperatures to achieve a reasonable signal/noise ratio.…”

Designing Photovoltaic Devices Using HgTe Nanocrystals for Short and Mid‐Wave Infrared Detection

“…Future developments will either have to identify strategies to reduce the effective absorption depth, for example, by introducing plasmonic resonator. Early results in this direction have been obtained. However, in this direction, it will be critical to keep the loss in a metal low.…”

“…Significant improvements were also obtained regarding the integration of the material into devices. Recent device developments include the demonstration of HgTe‐based field‐effect transistor and phototransistor, introduction of resonators to enhance the device light absorption, achieve pixel‐level spectral filtering or to achieve polarization‐sensitive detector . Devices with multicolor detection have been demonstrated either in the visible and in the IR, or in different IR fields such as SWIR/MWIR and MWIR/LWIR .…”