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 using 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(omega) intersect almost at the same wavelength. The theoretical frequency dependences T(omega) with allowance for substantial contribution of the intersubband transition of charge carriers in the valence band were calculated. The 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 was observed for x = 0.040-0.047. The possible influence of tellurium precipitates on the transmittance decrease in Cd1 - xZnxTe in the wave number range of 3000-400 cm(-1) is discussed. (C) 2001 MAIK "Nauka/Interperiodica".