Northwestern University team develops room temperature infrared imaging technique
InAs and GaSb combination would allow cheaper, more compact systems
A team of researchers at Northwestern University's Center for Quantum Devices (CQD) has used InAs and GaSb to develop mid-wavelength infrared (MWIR) detectors that can work at room temperature.
The researchers believe the development offers an alternative to current commercial technologies for MWIR detection, such as InSb and mercury-cadmium-telluride (MCT), that can only operate at cryogenic temperatures in order to reduce thermal and electrical noise.
"A higher operating temperature eliminates the need for liquid nitrogen," said Manijeh Razeghi, Walter P. Murphy Professor of Electrical Engineering and Computer Science and director of the CQD at Northwestern's McCormick School of Engineering and Applied Science. "That makes detectors more compact, less expensive, and more portable."
Razeghi and her group developed InAs/GaSb type II superlattice that demonstrated high-resolution MWIR images while operating at high temperatures. The new technique was particularly successful at obtaining infrared images of the human body, which has potential for vascular imaging and disease detection.
MWIR radiation has a wide range of applications from aerial surveillance to cancer detection. As the uses for high-sensitivity, high-resolution imaging continue to expand, MWIR sources are becoming more attractive. Depending on its use, infrared radiation is divided into several wavelength segments. MWIR have a radiation range between 3-5 microns; cameras able to see in this wavelength are capable of passive infrared imaging.
'Demonstration of type-II superlattice MWIR minority carrier unipolar imager for high operation temperature application' by Guanxi Chen et al appears in Optics Letters, Vol. 40, Issue 1 http://dx.doi.org/10.1364/OL.40.000045
