Semi-Empirical model for optical properties of $\text{Si}_{1-x}\text{Ge}_{x}$ alloys accounting for strain and temperature

A semi-empirical model for the optical properties of SiGe alloys is proposed, based on physical considerations and the summation of Tauc-Lorentz and parametric oscillators. The key parameters of the oscillators are intuited from the optical transition and the symmetry points in the band structure. The model is fitted on extensive experimental data, for different temperatures, germanium concentrati...