Dispersion of refractive index in degenerate mercury cadmium telluride

The work presents an approximate expression for refractive index of mercury cadmium telluride (Hg_1-xCd_xTe) applicable to both intrinsic and degenerate material. The relation is applicable for cadmium mole fractions x=0.165-1 at 300 K and 0.165-0.54 at 77 K and electron concentrations up to 10¹⁷cm^-3. The results are compared to available experimental data and to the results of calculation using Kramers-Kronig relation. A unified expression for interband absorption coefficient based on the Kane three-band model was used in the calculation, whilst the Urbach band-tailing and the electron-electron interaction were also taken into account