Researchers from Northwestern University's McCormick School of Engineering and Applied Science have developed the world's highest quantum efficiency ultraviolet (UV) photodetector, an advance in technology that could aid in the detection of missiles and chemical and biological threats.
The development of UV photodetectors has been driven by numerous applications in the defense, commercial, and scientific arenas. Until recently, photomultiplier tubes or silicon photodectors with UV band-pass filters were the only viable options for imaging in this important spectral range. Thanks to technological and scientific advances in the III-Nitride material system, high aluminum composition AlxGa1-xN-based semiconductor structures have become a promising alternative.
Manijeh Razeghi, Walter P. Murphy Professor of Electrical Engineering and Computer Science at McCormick, and her group have brought this AlxGa1-xN-based dream device closer to reality by developing a compact photodetector with the world's highest quantum efficiency.
"Heat sources such as flames, jet engines, or missile plumes emit light throughout the UV portion of the spectrum corresponding to their black-body temperature," said Razeghi, director of Northwestern's Center for Quantum Devices. "These manmade UV sources can easily be detected at wavelengths less than 290 nanometers due to the non-existence of a terrestrial background signature. The military, in particular, is interested in developing ground- and air-based solar-blind sensors to detect the UV signature of an active missile plume and provide early warning and potentially allow for missile tracking and ultimately interception."
The military could also use the UV detectors and sources to detect biological threats.
"Biological agents could have devastating effects on public health, as the anthrax scare of 2001 made us all too aware," said Erdem Cicek, a graduate student in Razeghi's lab. "There is a sig
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