DETERMINATION OF THE FAR-INFRARED OPTICAL-CONSTANTS OF ETA-DOPED BULKCDXHG1-XTE (CMT) BY DISPERSIVE FOURIER-TRANSFORM SPECTROSCOPY

Far infrared phase and amplitude reflectivity measurements have been m ade on two bulk CdxHg1-xTe mixed crystals with composition x=0.29 and x=0.22 by dispersive Fourier transform spectroscopy (DFTS). The result s have been used to calculate the real and imaginary parts of the diel ectric function (epsilon',epsilon '') from the Fresnel relations. A pl asma contribution is observed in the spectra in addition to the phonon respone. For both samples a broad but weak reflection band around 95- 105 cm(-1) is observed as well as the expected two-oscillator response from the HgTe-like and CdTe-like optical phonons. This feature is att ributed to absorption due to phonon combination bands, but it is too b road to enable assignments to be made. There is no evidence of additio nal features in the CdTe region due to clustering.