A Low-Cost Photodetector For The Long-Wave IR

A research team has created a low-cost colloidal quantum dot photodetector that can sense long-wave infrared (IR) light and may eventually replace more expensive commercially available options. According to the researchers, the new technology closes a gap in the photodetection spectrum and may be helpful for environmental monitoring, food inspection, and gas analysis.

With silicon photodetectors easily available for the visible/near-IR range and InGaAs photodetectors for the short-wave IR region, photodetector technology has been rather fragmented until now. Although there are devices for the mid-and long-wave IR, such as CdHgTe or more exotic detectors, they are frequently expensive, difficult to produce, and not CMOS compatible.

Researchers considered using colloidal quantum dots to produce a mid- and long-wave IR photodetector as a less expensive option. (QDs). They chose to concentrate on lead chalcogenide (PbS) colloidal QDs in particular because previous research with the substance in solution had discovered steady-state intraband absorption in the conduction band.

PbS quantum dots have proven they have the performance and affordability to contend with InGaAs in the short-wave infrared. Additionally, they work with CMOS devices. To ultimately have a single material platform for everything affordable and CMOS-compatible, researchers wanted to extend the spectral reach of this material platform towards the mid- and long-wave infrared.

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