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Swept away. QWIPs are fast and can have ideal (~100%) absorption tool

: Liu, H.C.; Dudek, R.; Oogarah, T.; Grant, P.D.; Wasilewski, R.; Schneider, H.; Steinkogler, S.; Walther, M.; Koidl, P.


IEEE circuits and devices magazine 19 (2003), Nr.6, S.9-16
ISSN: 8755-3996
Fraunhofer IAF ()
QWIP; infrared; Infrarot; InGaAs/GaAs

The ultra high-speed capability of quantum-well infrared photodetectors (QWIPs) is well known, thanks to their intrinsic short carrier lifetime (about 5 ps). This obviously makes QWIPs well suited for high-speed and high-frequency applications. In the past, for thermal infrared imaging where devices are optimized to have the highest possible detectivity, the absorption quantum efficiency has been low (<10%). For high-speed applications where lasers are usually used, the most important parameter is the absorption efficiency. We show that high absorption (about 100%) can be easily achieved by simply changing some of the device parameters. We also review the experimental demonstrations of the high-speed capability. At present, QWIPs hold the unique position of having high-speed/-frequency capability and high absorption for the thermal infrared region. There are no competitive alternatives.