<title>Model dielectric functional of amorphous materials including Urbach tail</title>

Abstract

A generalization of the Tauc-Lorentz model dielectric function of amorphous semiconductors and dielectrics is presented in which the exponential Urbach tail is included. The generalized parameterization of the optical functions includes only six fitting parameters. The real part of the dielectric function is calculated using analytical Kramers-Kronig dispersion relations. The model is applied to hydrogenated amorphous silicon.