Switching-peak GaAs/AlGaAs multistack quantum well infrared detector

Abstract

A novel type of intersubband GaAs/AlGaAs infrared detector for the range 6–12 μm is described. It consists of three different stacks of quantum wells, each stack designed for response at a different peak wavelength. The detector can operate in a number of modes: a) standard bound- to-continuum detector; b) wide-band intersubband detector; c) switching-peak tunable detector. All operations are controlled by the applied voltage. The device displays excellent responsivity and detectivity figures of merit. The peak-switching and tunability properties are due to the formation and readjustment of high and low electric field domains within the superlattice. Carriers in the high-field regions contribute to the photoresponse; carriers excited by the incident infrared light in the low-field domains have a large probability of being recaptured by their original quantum well, thus contributing negligibly to the photocurrent. It is shown that infrared photocurrent spectroscopy is an excellent tool to study the structure of electric field domain in doped or otherwise carrier-rich superlattices.