Prediction of optical properties of amorphous tetrahedrally bonded materials

A new approach is described for the prediction of the optical properties of amorphous tetrahedrally bonded materials over the entire experimental energy range, in which a model of the imaginary part of the dielectric constant is assigned and the real part is obtained by the Kramers–Kronig transform. Tight-binding theory provides direct interpretation of the model parameters. The model provides good insight into the physics of the problem and a quantitative account of experimental data as well. Results are presented for Si, Ge, Si3N4, and GaAs.