Low frequency phonon spectra of mixed crystal CdxHg1−xTe

Far infrared absorption spectra for the mixed crystal Cd_xHg_1?xTe with x=0.18 to 0.45 in the wavenumber region of 10 to 400cm^?1 and temperature region of 4.5 to 300K are reported. A low frequency absorption band has been found between 20 and 50 cm^?1 for all the samples which have been measured in addition to the two-phonon bands in both sides of the reststrahlen absorption bands of the material. By comparison with the phonon densities of states estimated from the phonon frequencies of CdTe, we have attributed this band to TA band modes induced by the disorder and “impurity” effects.