The fundamental absorption edge of CuGa_(3)Te_(5) ordered defect semiconducting compound

The analysis of the temperature variation of the optical absorption spectra of the ordered defect compound CuGa_(3)Te_(5), a semiconducting material which crystallizes in a chalcopyrite-related structure with space group P‾42c, is made. It has been established that this compound has a direct-allowed band gap between parabolic bands which varies from 1.187 to 1.090 eV in the temperature range from 10 to 300 K. The mean temperature of the phonon involved in the direct band-to-band transition is θ ≈ 125 K. This is comparable with 3/4 θD ≈ 156 K, θD being the Debye temperature of the compound.