Optical properties of small period superlattices

Abstract

The existence of minibands of extended states gives to short-period superlattices optical properties quite different from those of multi-quantum wells. The heavy-hole/light-hole splitting is reduced together with the binding energy of excitons and impurities. Vertical transport becomes possible and a recovery of the 3D mobility of the average alloy is observed for very shirt period superlattices. The excitation (PLE) spectra are sensitive to the possible escape of carriers in the direction perpendicular to the layers. New structures, related to the miniband structure, in particular to the existence of saddle-points at the Brillouin zone edge, can also be observed in PLE spectra and analysed in magneto-PLE experiments. Finally, short-period superlattices are attractive systems to study the localization of eigenstates by scattering, disorder or an electric field.