Quantum well infrared photodetectors for low background applications

Quantum well infrared photodetectors (QWIPs) afford greater flexibility than the usual extrinsically doped semiconductor IR detectors. The wavelength of the peak response and cutoff can be continuously tailored over any wavelength range between 6-20 mum. The spectral band width of these detectors can be tuned from narrow (Delta lambda/lambda similar to 10%) to wide (Delta lambda/lambda similar to 40%) allowing various applications. Also, QWIP device parameters can be optimized to achieve extremely high performances at high back ground at lower operating temperatures (similar to 30 K). However, for low-background irradiance levels at low operating temperatures, high resistivity of the active region could leads to nonlinear responsivity behavior. A new structure with a photosensitive superlattice and a thick blocking barrier has been tested, and is expected to avoid anomalous behavior under low backgrounds at low temperatures. (C) 2001 Elsevier Science B.V. All rights reserved.