Atomic configuration and far-infrared optical spectra of lattice vibrations of Zn-Te and Cd-Te modes in Cd1-xZnxTe (x=0-0.2)

Lattice reflection spectra of Cd1-xZnxTe (x = 0-0.2) alloys have been analyzed using the Kramers-Kroning method, and the function of the crystal dielectric permeability has been restored from the reflection spectra using dispersion analysis with subsequent expansion into Lorenz contours of lattice oscillators. The oscillator frequencies correspond to four CdTe oscillation modes and four ZnTe modes in accordance with the model for the CdZnTe structure consisting of five Cd(4 - n)Zn(n)Te (n = 0-4) basis tetrahedral cells of Cd and Zn cations around one common Te anion. Analysis of the lattice oscillator strengths for compositions x = 0.06-0.2 revealed no deviation from the random Cd and Zn distribution over the cation sublattice. At x approximate to 0.05, the experimental distributions deviate drastically from the theoretically predicted oscillator strengths. For this reason, we treated the data for 0.04 < x < 0.05 under the assumption that the electronic density of the CdTe bonds is shifted toward Te. This phenomenon may initiate the formation of Te-Te centers with a localized hole and violates the cubic symmetry in the vicinity of Te atoms.