Optical properties of Wurtzite-type semiconducting crystals near the isotropic point

Summary Using Stahl's coherent wave approach we calculated the linear interband susceptibility near the band gap. The starting point was the ?MGM? formula with a smeared-out dipole densityM(r) and the Green's functionG for the effective-mass Hamiltonian with a screened Coulomb potential. The susceptibility so obtained was used for calculating transmission spectra of CdS platelets for energies near the so-called isotropic point lying far below the nearest excitonic resonance. By fitting experimental spectra we determined components of the residual dielectric tensor for polarization of the incident beam perpendicular and parallel to thec-axis, the mixed-mode dipole moment corresponding toB-exciton, and decay radii characterizing transition dipole densities. The established set of parameters determines the dielectric tensor for a quite wide energetic range.