Optical properties of Cd1-xZnxTe (0 < x < 0.1) single crystals in the infrared spectral region

Frequency dependences of the transmittance T(omega) of Cd1 - xZnxTe (0 < x < 0.1) single crystals grown by a modified Bridgman method were studied usi ng long-wavelength optical spectroscopy in the temperature range of 5-300 K . A sharp increase in absorption for energies smaller than the band gap was observed for unannealed samples of p-type conductivity. Moreover, with the temperature variation of the sample from 5 to 300 K, the dependences T(ome ga) intersect almost at the same wavelength. The theoretical frequency depe ndences T(omega) with allowance for substantial contribution of the intersu bband transition of charge carriers in the valence band were calculated. Th e Fermi level position was evaluated for the samples at T = 77.3 and 295 K. A nonmonotonic dependence of the Fermi level position on the composition w as observed for x = 0.040-0.047. The possible influence of tellurium precip itates on the transmittance decrease in Cd1 - xZnxTe in the wave number ran ge of 3000-400 cm(-1) is discussed. (C) 2001 MAIK "Nauka/Interperiodica".