Interband Critical Point Parameters Determined by Ellipsometry in CdxHg1−xSe

The dielectric function of CdxHg1−xSe crystals, with x = 0 to 0.30, is measured by ellipsometry at room temperature between 1.8 and 5.5 eV. The E1 and E1 + Δ1 gaps and the Δ1 spin—orbit splitting show a upwards quadratic dependence on composition. The broadening of the observed structures increases with x due to alloying effects and disorder or to the difference in chemical activity of the surfaces. The results are discussed in comparison with those obtained for ZnxHg1−xSe and CdxHg1−xTe.