MODEL DIELECTRIC FUNCTION OF HEXAGONAL CDSE

We present a calculation of the complex dielectric function, ε(ω)=ε1(ω)+iε2(ω), at energies below and above the fundamental absorption edge of the hexagonal, wurtzite-type semiconductor CdSe. This model includes the E0, E 1, and Eidg (indirect) gaps as the main dispersion mechanisms. The model is made to properly account for the excitonic effects at these critical points. Results are in satisfactory agreement with recent ellipsometric measurements over the entire range of photon energies (E=0-5.0 eV). Detailed discussions are presented on the results, with emphasis on the information about the electronic energy-band structures and their group-symmetrical selection rules of this material.