Avalanche Photodiodes and Why Solid State Physicists Rule
By Christopher MooreSolid state physicists are contributing to the battle against terrorism. And unfortunately for pseudoscientist “new paradigm” theory hawkers, quantum physics has another application.
In this article, PhysOrg.com discusses newly developed Avalanche Photodiodes (APDs) and their application in the war on bio-terror.
Once optimized, these sensitive detectors could be combined with the ultraviolet light-emitting diodes (LEDs) already pioneered by the Center for Quantum Devices to create an inexpensive detection system capable of identifying the unique spectral fingerprints of a biological agent attack.
The APD technology may see further use in the deployment of systems for secure battlefield communication. Wavelengths around 280 nanometers are referred to as the solar-blind region; in this region, the UV light is filtered out by the ozone layer providing for a naturally low background signal. Solar-blind APDs are intrinsically able to take advantage of this low background level, while PMTs must use external filters to become solar-blind. This makes secure battlefield communication possible utilizing a combination of compact, inexpensive UV LEDs and UV APDs both developed at the Center for Quantum Devices.
You can learn more about how APDs work here.
Solar blind APDs rely on the wide band-gap AlGaN semiconductor. Unfortunately, current AlGaN growth techniques lead to a large number of crystalline defects. But the Center for Quantum Devices reports AlGaN crystals exhibiting solar blind avalanche gain.
My research group has worked on GaN defect reduction. A recent paper on these efforts can be found here.
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