With the amazing potential to survey areas in absolute darkness, night-vision cameras have revolutionized the security industry. But the materials and technology embodied in present cameras tend to degrade under temperature stress, resulting in night-vision devices to frequently break.
Northwestern University’s Maijeh Razeghi and her group have introduced a novel method to enhancing the technologies in night-vision cameras, potentially making these all too frequent breakdowns a thing of the past. Razegi’s group introduced a breakthrough design of strained-layer indium arsenide atimonide type-II superlattices, a core component of making high-performance, long-wavelegnth infrared photodetectors for distinct applications, including night-vision cameras.
“With a special superlattice based electron constraint, the newly designed photodetector limits the obstructing dark current density, while raising the background limited infrared photodetection temperature,” says Razeghi, Walter P. Murphy Lecturer of Electrical Engineering and Computer Science in Northwestern’s McCormick School of Engineering. “This allows the infrared cameras to perform imaging at higher operating temperatures and reduced the requirement for cryogenic cooling power inside the camera.”
Supported by the Air Force Research Laboratory, Defence Advanced Research Projects Agency, and US Army. Razeghi’s novel photodetector can identify the light signals from wavelengths up to 10 microns, which is the same wavelength released emitted by the human body. Present state of the art photodetectors are made with mercury cadmium telluride, for which researchers have long been looking for alternatives as it degrades under thermal stress. Mercury also possesses well-known health and environmental dnagers.
Razeghi’s team in Northwestern’s Centre for Quantum Devices is the foremost replace mercury with indium arsenide antimonide type-II superlattices. Not just is the novel replacement safer than mercury, it is also more durable. Mercury-cadmium-telluride possesses heat-sensitive ionic bounds that degrade under extreme high temperatures.
Conclusion – Efforts to use indium arsenide antimonide type-II superlattices in the past resulted in photodetectors with shorter life spans and inferior optical performance. But Razeghi and her group overcame this long-lasting scientific challenge by introducing a ‘saw-tooth superlattic design’, which acted as an electron constraint to safeguard the substance and prevent degradation.
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