A comparison among the results of various dispersion relations for the ellipsometric data of Mn:ZnO thin films using PSO algorithm

Using particle swarm optimization (PSO) algorithm, the Cauchy, Forouhi-Bloomer (FB) and Sellmeier parametrization models were compared for the Mn doped ZnO (Mn:ZnO) thin films. The variation of both refractive and extinction coefficients with Mn concentration was also discussed. Our calculations demonstrate that despite the Sellmeier model exhibits the best fit with the lowest root-mean-square error (RMSE) in the transparent region, the FB model is well-suited in the both transparent and absorbing areas. Different energy gaps, roughnesses and thicknesses were obtained by the mentioned models. A comparison with the results of Tauck-Loretz model along with an exciton-based dielectric function were also done for our results.