Long-wavelength interface modes in semiconductor layer structures

We address and explain the occurrence of bulk and interface modes in zinc-blende group-III-group-V semiconductor layer structures observed by spectroscopic ellipsometry at infrared wavelengths. Fano- and Brewster-type transverse-magnetic (p-polarized) interface modes as well as transverse-electric (s-polarized) surface-guided interface modes are assigned by solutions of the surface polariton dispersion relations for polar semiconductor layer structures. We show that the Berreman-effect [D. W. Berreman, Phys. Rev. 130, 2193 (1963)] is associated with the occurrence of a Fano-interface polariton. Experimental verification is demonstrated for a GaAs homostructure, which consists of differently Te-doped n-type substrates covered by undoped epilayers.