Parametric modeling of the dielectric function and identification of the critical point of a CdMgTe alloy in the vacuum ultraviolet spectral range

We report the parameters necessary to construct the dielectric functions of Cd1−x Mg x Te ternary alloys at room temperature for arbitrary compositions from x = 0 to x = 0.5. The experimental spectra were measured by using vacuum ultraviolet spectroscopic ellipsometry in the spectral range from 0.7 to 9.0 eV. By performing a band structure calculation with the linear augmented Slater-type orbital method, we newly identify the four higher band gaps as E 2 + Δ2, E 2(Δ), E 2(Σ), and E′1 transitions.