Inexpensive QWIP array sees broad IR wavelength range

A quantum-well infrared photodetector (QWIP) array developed by NASA and the Army Research Lab was the world’s largest (one million pixel) IR array when the project was announced in March 2003. At that time it could only detect a narrow range of IR wavelengths between 8.4 and 9.0 µm. A new version of that QWIP array is the same size but can now sense IR over a broader and more “colorful” range, between 8 and 12 µm. The advance was based on varying the composition and thickness of the detector material layers in the device’s quantum wells to detect light with different energy levels.

NASA’s QWIP detector is a gallium arsenide (GaAs) semiconductor chip with more than 100 (10 to 700 atoms thick) wells. The QWIP arrays are also relatively inexpensive because they can be fabricated using standard semiconductor technology. “The broad response of this array, particularly in the far-IR, is crucial for IR spectroscopy,” said Murzy Jhabvala, principal investigator for the project at NASA’s Goddard Space Flight Center (Greenbelt, MD). Contact Murzy Jhabvala at murzy.d.jhabvala@nasa.gov.