ABSTRACT
Considerable progress has been made in the development of multiple quantum well heterostructures for long-wavelength infrared detection. In these quantum well infrared photodetectors, intersubband transitions are used to photo-excite a carrier-an electron or a hole-from a filled ground state to a higher subband state near the top of the quantum well. The exact nature of the optical transition involved in the p-type photoresponse has proven difficult to model. For instance, most reports describe the photoresponse as due to a transition from the first heavy hole state to an extended subband state in the continuum. Since the selection rules for bound-to-bound and bound-to-continuum transitions depend on band content of the final and initial states, it is of interest to present envelope function plots. In order to obtain a better understanding of the behavior of the valence subband wave functions over the entire Brillouin zone, it is best to provide their band-by-band decomposition as explained in the section on normalization.
