LINE-SHAPE OF ELECTROREFLECTANCE SPECTRA IN SEMICONDUCTOR SUPERLATTICES

Electroreflectance (ER) spectra of GaAs-AlAs superlattices in a perpen dicular electric field exhibit complicated line shapes that cannot be explained by the presence of heavy-hole and light-hole excitonic trans itions alone. Calculations of the absorption and ER spectra have been performed to investigate the influence of interference effects and tra nsitions between continuum states on the corresponding line shape. Int erference effects can lead to additional structures in the ER spectra that can be misinterpreted as additional transitions. A comparison of the experimental and calculated spectra shows that the presence of con tinuum states can contribute to the ER spectra. In this case, experime ntal ER spectra can only be simulated if contributions from band-to-ba nd transitions and interference effects are taken into account. Theref ore, a total of four rather than just the two excitonic transitions (h eavy and light hole) are used.