Abstract
A new method is described for the calculation of the refractive index of semiconductors at energies below the lowest band gap, in which a model form of the imaginary part of the dielectric function is assigned and the refractive index is obtained, without introducing any empirical parameter. It provides good insight into the physics of the problem and a quantitative account of refractive index dispersion as well. Double-beam reflectance measurements were made for the refractive index of four InP and GaAs samples. Results are presented for Si, Ge, AlAs, GaP, GaAs, and InP and show very good agreement with this model.