Dual-band infrared imaging using stacked colloidal quantum dot photodiodes

Infrared multispectral imaging is attracting great interest with the increasing demand for sensitive, low-cost and scalable devices that can distinguish coincident spectral information. However, the widespread use of such detectors is still limited by the high cost of epitaxial semiconductors. In contrast, the solution processability and wide spectral tunability of colloidal quantum dots (CQDs) have inspired various inexpensive, high-performance optoelectronic devices. Here, we demonstrate a twoterminal CQD dual-band detector, which provides a bias-switchable spectral response in two distinct bands. A vertical stack of two rectifying junctions in a back-to-back diode configuration is created by engineering a strong and spatially stable doping process. By controlling the bias polarity and magnitude, the detector can be rapidly switched between short-wave infrared and mid-wave infrared at modulation frequencies up to 100 kHz with D* above 1010 jones at cryogenic temperature. The detector performance is illustrated by dual-band infrared imaging and remote temperature monitoring.

了解详情

Direct Optical Lithography Enabled Multispectral Colloidal Quantum-Dot Imagers from Ultraviolet to Short-Wave Infrared

Complementary metal oxide semiconductor (CMOS) silicon sensors play a central role in optoelectronics with widespread applications from small cell phone cameras to large-format imagers for remote sensing. Despite numerous advantages, their sensing ranges are limited within the visible (0.4−0.7 μm) and near-infrared (0.8−1.1 μm) range , defined by their energy gaps (1.1 eV). However, below or above that spectral range, ultraviolet (UV) and short-wave infrared (SWIR) have been demonstrated in numerous applications such as fingerprint identification, night vision, and composition analysis. In this work, we demonstrate the implementation of multispectral broadband CMOS-compatible imagers with UV-enhanced visible pixels and SWIR pixels by layer-by-layer direct optical lithography of colloidal quantum dots (CQDs). High-resolution single-color images and merged multispectral images were obtained by using one imager. The photoresponse nonuniformity (PRNU) is below 5% with a 0% dead pixel rate and room-temperature responsivities of 0.25 A/W at 300 nm, 0.4 A/W at 750 nm, and 0.25 A/W at 2.0 μm.

了解详情

Megapixel large-format colloidal quantum-dot infrared imagers with resonant-cavity enhanced photoresponse

Infrared imaging is extensively explored due to its unique properties of high atmospheric transmission and temperature-dependent emission. Unfortunately, the current epitaxial infrared materials suffer from a complicated fabrication process and low production yield, which hinders the further development of infrared imaging for civilian applications. As an alternative to epitaxial semiconductors, the wide spectral tunability and optical versatility of colloidal quantum dots (CQDs) have provided a promising route for infrared detection. Here, we demonstrate an infrared imager that integrates HgTe CQDs with complementary metal-oxide-semiconductor (CMOS) readout integrated circuits. Moreover, the underlying metal contacts and passivation layer of the CMOS chip play a role as an in-pixel resonant-cavity , which enhances the absorption of the CQDs film. The CQDs imager exhibits a detectivity of 2.8 × 1010 Jones, an external quantum efficiency of 14%, and an operable pixel factor of over 99.99% for a cut-off wavelength of around 2 μm at room-temperature. With a large-format (1280×1024 pixels2) and a small pixel pitch of 15 μm, the resolution of the imager can reach 40 line pairs per millimeter (lp/mm). The performance of the CQDs imager is demonstrated by infrared imaging. © 2023 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

了解详情