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The energy spectrum of the superlattice structure is analysed in detail, assuming that the spatial distributions of the potential energy and the effective mass are rectangular. It is shown that both wells and barriers may appear in the first and second materials, depending on the transverse component value of the wave vector. Two ZEG (zero energy gap) conditions are also derived; the second one being a direct consequence of the spatial dependence of the effective mass. The numerical analysis of results is performed on Bl,Gal-,As-GaAs superhttice structure. This numerical results confirm theoretical results exposed in the first part of the paper.Le spectre bnergbtiquc dc lo structure du super-rbeau a 6th nnalysh en dbtail, supposant que les distributions spatiales de l'bnergie potentielle et de la masse effective sont rectangulaires. On B d6montrc que tous les deux, les puits et les borrieres de potentiel peavent apparaEtre dans tous les deux matbrisux, dbpendant de la valeur des composantes transversnles du vecteur d'onde. O n a dbriv6 aussi deux conditions"ZEG"; la seconde btant lo conskquence directe dc la dbpendmce spatiale cle In. niasse effective. L'analysc numbrique des rksultats o k t b faite sup la structure du supcr-rC.seuu Bl,Gn~-,As-GaAs.Les rksultats numbriques confirment les rksultats thkoriques prksentbs dans Is premiere partie de cet article.

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The spectral characteristics of intraband absorption on bound-free transitions in semiconductor quantum wells are analyzed. Numerical results indicate that both comparatively narrowband (∼30 meV) and broadband (≳200 meV) absorption may occur, which may be important in infrared detector design.

Starting from the continuous energy spectrum of a quantum well subjected to a perpendicular electric field, electro-absorption is analysed within the effective-mass approximation. The electric field considered is assumed to be strong enough that the exciton effects may be neglected. The influence of the difference between the well and bulk effective masses on the electron and hole wavefunctions, as well as on absorption, is thoroughly discussed. The absolute values of the well absorption are determined for a couple of examples.