By Josh Perry, Editor [email protected]
Scientists from the University of Chicago (Ill.) made a breakthrough using quantum dots that could make the manufacture of infrared cameras easier, faster, and more cost-effective and could make those cameras more readily available for applications such as smartphones and autonomous vehicles.
Photos taken by researchers testing a new method to make an infrared camera that could be much less expensive to manufacture. (Xin Tang/University of Chicago)
Rather than building the camera through layers of semiconductors, according to a report from the university, the researchers tuned quantum dots so one would pick up short-wave infrared wavelengths and one would pick up mid-wave infrared and laid both onto a silicon wafer.
The scientists insist that this is a quick and easy process (5-10 minutes) to create a functional device.
“There are many potential uses for inexpensive infrared cameras,” the article noted, “including autonomous vehicles, which rely on sensors to scan the road and surroundings. Infrared can detect heat signatures from living beings and see through fog or haze, so car engineers would love to include them, but the cost is prohibitive.”
The research was recently published in Nature Photonics. The abstract stated:
“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 two-terminal 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.”
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