Field-dependent absorption in superlattices: Comparison of theory and experiment

Absorption and differential electroabsorption spectra of a GaInAs/InP superlattice in the regime of Wannier-Stark localization are compared with spectra derived from the Semiconductors Bloch Equations. The absorption is strongly underestimated for higher energies by the effective mass approximation but good agreement is achieved by using an energy dependent in-plane effective mass. No fitting parameters are used except for a phenomenological broadening. The lineshape of the field-modulated spectra is dominated by the strong field dependence of Wannier-Stark transitions and depends on the amplitude of the modulating field which should be kept small for best results. (C) 1998 American Institute of Physics. [S0003-6951(98)01044-4].