<title>Recent progress in quantum well infrared detectors</title>

Abstract

Dramatic progress in the study of intersubband transitions in quantum wells in recent years has led to the fabrication of high sensitivity infrared detectors and focal plane arrays. The use of different material systems, using both III-V compounds and silicon-based has allowed a wide wavelength coverage from 3 to 20 /µn. Novel device architectures have also been incorporated to overcome the polarization selection rule and to allow the fabrication of multicolor detectors. For example, random gratings on the detector and strained quantum well structures have been incorporated for normal incident detection. For multicolor detection and the tuning of detection wavelength, asymmetric quantum well structures have been utilized. In this paper, we will first review intersubband transitions in symmetric and asymmetric quantum well structures and then discuss recent progress of normal incident quantum well infrared detectors. Finally, the trends towards the realization of multicolor detectors and large area infrared imagers will be discussed.