We report on the application of generalized ellipsometry at far-infrared wavelengths (150-600 cm(-1)) for measurement of the anisotropic dielectric response of doped polar semiconductors in layered structures within an external magnetic field. Measurement of normalized Mueller matrix elements allows for independent determination of the free-charge-carrier parameters density, mobility and effective mass for semiconductor alloy materials in layered structures upon application of the Drude model, thereby dispensing with the need for electrical measurements. Examples reviewed here include n-type/i-type GaAs, n-type GaAs/n-type Al0.19Ga0.33In0.48P/i-type GaAs, and n-type B0.03In0.06Ga0.91As/i-type GaAs layer structures, measured at room-temperature and magnetic fields up to +/-3 T. (C) 2003 Elsevier B.V. All rights reserved.