Dielectric function of GaN: model calculations

In this work we have modeled the optical functions of hexagonal GaN (corresponding to E perpendicular to c) in the range from 1 eV to 10 eV using a modified critical points model. The difference between the model employed and the standard critical points model is that the exponent m is an adjustable parameter, and does not have fixed value depending on the type of critical point. Excellent agreement with the experimental data has been achieved over the entire investigated spectral range. Obtained relative rms errors equal 0.6% for the real part, and 2.0% for the imaginary part of the index of refraction.