Line shape of electroreflectance spectra in semiconductor superlattices
Linienform von Elektroreflektions-Spektren in Halbleiter-Übergittern
Electroreflectance (ER) spectra of GaAs-AlAs superlattices in a perpendicular electric field exhibit complicated line shapes that cannot be explained by the presence of heavy-hole and light-hole excitonic transitions alone. Calculations of the absorption and ER spectra have been performed to investigate the influence of interference effects and transitions between continuum states on the corresponding line shape. Interference 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 continuum states can contribute to the ER spectra. In this case, experimental ER spectra can only be simulated if contributions from band-to-band transitions and interference effects are taken into account. Therefore, a total of four rather than just the two excitonic transitions (heavy and light hole) are used.