Abstract

Carrier confinement in ultrathin semiconductor heterostructures leads to energy quantization. These artificial energy levels can be tailored to match any optical transition in the 3–20-µm-photon wavelength range by adjusting the quantum well width and the barrier composition. Optical transitions between bound and extended levels of these quantum wells give rise to a photocurrent, which is exploited for photon detection in Quantum Well Infrared Photoconductors (QWIPs). In this communication, we summarize the present understanding of the physics of QWIP detection: photoexcited carrier emission and capture probability, contact injection, and noise mechanisms. We also present the current status of the QWIP technology for infrared staring arrays and illustrate the major advantages of this new technology:

• Standard III-V substrates and technology, thermal stability, uniformity, large areas, low development costs, radiation hardness

• Adjustability from 3 to 20 µm

• New functions: multispectrality, spectrophotometry, band switching, optical reading.

© 1994 IEEE