Dependence of IR optical properties of bulk-doped silicon on carrier concentration

The infrared optical constants (index of refraction and extinction coefficient) and reflectance of bulk-doped n-silicon are calculated for electron concentrations up to 1021 cm-3. These calculations are based on generalized Drude-Lorentz form of dynamic dielectric function and current relaxation approach. A nonmonotonic behavior of IR absorption versus electron concentration is found. A connection between the theoretical results and available experimental data is discussed.