Mercury Telluride Quantum Dot Based Phototransistor Enabling High-Sensitivity Room-Temperature Photodetection at 2000 nm

Abstract

Near-to-mid-infrared photodetection technologies could be widely deployed to advance the infrastructures of surveillance, environmental monitoring, and manufacturing, if the detection devices are low-cost, in compact format, and with high performance. For such application requirements, colloidal quantum dot (QD) based photodetectors stand out as particularly promising due to the solution processability and ease of integration with silicon technologies; unfortunately, the detectivity of the QD photodetectors toward longer wavelengths has so far been low. Here we overcome this performance bottleneck through synergistic efforts between synthetic chemistry and device engineering. First, we developed a fully automated aprotic solvent, gas-injection synthesis method that allows scalable fabrication of large sized HgTe QDs with high quality, exhibiting a record high photoluminescence quantum yield of 17% at the photoluminescence peak close to 2.1 μm. Second, through gating a phototransistor structure we demonstrate room-temperature device response to reach >2 × 10 cm Hz W (at 2 kHz modulation frequency) specific detectivity beyond the 2 μm wavelength range, which is comparable to commercial epitaxial-grown photodetectors. To demonstrate the practical application of the QD phototransistor, we incorporated the device in a carbon monoxide gas sensing system and demonstrated reliable measurement of gas concentration. This work represents an important step forward in commercializing QD-based infrared detection technologies.

HgTe Nanocrystal Inks for Extended Short‐Wave Infrared Detection

“…On the other hand, efforts dedicated to the integration of HgTe nanocrystals into photodiodes are much fewer than those reported for PbS. As a result, most devices based on HgTe nanocrystals with long wavelength absorption are based on planar geometries …”

“…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

“…In the recent years, HgTe has been widely used to explore devices with absorption above 2 μm . Pushing the nanocrystal absorption toward longer wavelength requires to update the device architecture.…”

“…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 .…”

Narrow‐Band QD‐Enhanced PIN Metal‐Oxide Heterostructure Phototransistor with the Assistance of Printing Processes

“…In particular, due to the negative bandgap (−0.3 eV) of the topological insular HgTe and direct bandgap of CdTe (1.7 eV), the PIN heterostructure composed of these materials has tremendous potential for use in any infrared (IR) waveband. In this letter, we describe ternary compound semiconductor QDs (CdHgTe, mercury telluride, mercury cadmium tellurium (MCT) QDs) adopted as the optoelectric conversion core that can provide high light‐absorption and sensitivity in IR‐detecting applications . These characteristics motivate us to investigate the performance of the phototransistor with the assistance of an inkjet and dispensing printing process that can simplify the formation and alignment of the heterostructures.…”