Determination of CdAs2 band structure parameters by the optical transparency and photoconductivity methods

Optical absorption and photoconductivity spectra of CdAs2 anisotropic single crystals of perfect structure were first studied in the temperature range from 78 to 293 K. Both fundamental absorption edges (for E parallel to C (1) and E perpendicular to C (2)) were shown to be determined by indirect transitions involving excitonic states and a ≅ 130 meV - energy photon. The values of the exciton band gap were determined at 293 K: 0.98 eV for (1); 0.985 eV for (2) (indirect transition); and 1.3 eV for (1) (direct transition). The value of the exciton band energy is shown to be about 10 meV. 9 refs., 3 figs