Modeling the optical constants of AlxGa1-xN alloys

We have modeled the dielectric function of wurtzite AlxGa1-xN alloys for normal polarization in the energy range up to 10 eV and for all compositions 0 < x < 1. The employed model takes into account one-electron contributions to the dielectric function at E0, E1A, E1B, and E1C critical points, as well as excitonic contributions at those critical points. The model is very flexible, due to the use of adjustable broadening function instead of the conventional Lorentzian one. Model parameters are determined by acceptance-probability-controlled simulated annealing. We obtain excellent agreement with the experimental data for all available compositions.link_to_subscribed_fulltex