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-xMgxTe 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 Slatertype orbital method, we newly identify the four higher band gaps as E2 + Δ2, E2(Δ), E2(Σ), and E'1 transitions.