Far-infrared spectroscopy of CdTe/ZnTe self-assembled quantum dots

In this paper we present far-infrared (FIR) reflection spectra and results of photoluminescence (PL) measurements of CdTe/ZnTe self-assembled quantum dots (SAQD). The electronic band structure was characterized by a photoluminescence spectrum. The PL spectrum displayed two main emission peaks, both connected with existing of QDs. One presents direct deexcitation to ground state and the other is optical phonon assisted deexcitation. The FIR reflectivity spectra were measured in the spectral range of 70–650 cm−1. Analyses of the spectra were made by fitting parameters in the complex dielectric function that depends on 3D distribution of constituents. CdTe buffer and ZnTe dielectric barrier layer act as a bulk semiconducting crystal and have usual values for phonon frequencies. The confined CdTe modes from SAQD could not be completely resolved in FIR reflectivity spectra because these modes are hidden by the strong peak of CdTe buffer layer, but it was necessary to include a CdTe mode confinement in the fitting procedure in order to obtain good agreement with the experimental data.