Interface roughness transport in terahertz quantum cascade detectors

Abstract

Infrared detectors based on a quantum cascade have been proposed to suppress the dark current which is a limiting factor in quantum well infrared photodetectors. Those detectors have been mainly designed for the midinfrared wavelength. Operating in the terahertz range involves a complete change of regime of transport since the photon energy is lower than the optical phonon energy. Thanks to a two dimensional model of transport, we have identified interface roughness as the key interaction in such a structure. Interface parameters, evaluated by scanning transmission electron microscopy, are used to study their influence on the resistance of the device.