In-plane spectrum in superlattices

Abstract We show that the existing theory does not give correct in-plane spectrum of superlattices at small in-plane momentum. Magneto-absorption experiments demonstrate that the energy range of the parabolic region of the spectrum near the electron subband bottom is by the order of magnitude lower than the value predicted by the traditional approach. We developed a modified theory according to which the energy range of the parabolic region and carrier in-plane effective masses are determined by the effective bandgap of the superlattice rather than by the bulk bandgaps of the superlattice layers. The results of the new theory are consistent with the experiment.