Far infrared investigation of phonons and plasmons in p-doped GaAs–Al0.33Ga0.67As (311) superlattices

Far infrared measurements give detailed information on the phonon and plasmon contributions to the dielectric response of p-doped GaAs-Al0.33Ga0.67As superlattices grown on (311) GaAs substrates. The measured spectra are in good agreement with theoretical spectra which take account of the optical response of confined optical phonon modes in the dielectric function of the short period part of the structures and the directional dependence of the plasma response in the wells of the MQW part of the samples. The effect of surface roughness was included in modeling. We also report some evidence of intersubband transitions of holes by far infrared transmission measurements at the Brewster angle.