The dynamic dielectric function in HgSe and HgTe

Absorption measurements in the infrared region from 5 to 30 μm for HgTe at 295 K and for HgSe at 10, 80, and 295 K are performed. On the basis of the observed interference phenomena the dependence of the refractive index on the wavelength is obtained. These results are analysed in terms of the dynamic dielectric function. The contribution of the GAMMAsub(8)sup(V) → GAMMAsub(8)sup(C) transitions is calculated in terms of Kane's band structure model. From the comparison of theoretical results and experimental data the value of the high-freuqency dielectric constant as a function of temperature, treated as a fitting parameter, is determined. The temperature dependence determined for HgSe is somewaht different from that found for HgTe and differs from the value proposed earlier for HgSe. (author)