Carrier scattering approach to the origins of dark current in mid- and far-infrared (terahertz) quantum-well intersubband photodetectors (QWIPs)

A carrier scattering approach is taken in an analysis of the affect on the dark current of extending the operating wavelength of conventional bound to continuum quantum-well intersubband photodetectors. It is found that both the sequential tunneling and the thermionic emission contributions to the dark current increase as the wavelength of the detector is extended from the mid- to far-infrared. Dark current designs rules are derived.