Quantum cascade detectors

A photovoltaic intersubband detector based on electron transfer on a cascade of quantum levels is presented which we called a Quantum Cascade Detector (QCD). The highest photoresponse of intersubband transition based photovoltaic detectors is demonstrated: 44 mA/W at zero applied bias. Further improvements permit to suppress the leakage current and to increase the resistivity R0A. Useless cross-transitions have been eliminated finally leading to a high resistance narrow band photodetector with a Johnson noise limited detectivity at 50 K comparable to QWIPs. Because they work with no dark current, QCDs are very promising for small pixel and large focal plane array applications.