For a superlattice whose unit cell contained quasi-localized electron states, the electron spectrum structure was studied and the dipole matrix element of intersubband transitions was calculated. The dispersion relation and the band structure of such a superlattice were determined. The wave functions and the electron spectrum were found to possess peculiar hybrid properties near the energy corresponding to the quasi-localized state in an isolated quantum well. The absorption coefficient of the heterostructure in this region was substantially increased.
Department of Low-Temperature Physics, Faculty of Physics, Moscow State University, Leninskie Gory, Moscow, 119992, Russia