[01] Alioune Aidara Diouf, Faculty of Sciences and Techniques, Cheikh Anta Diop University of Dakar (UCAD), Dakar, Senegal. [02] Bassirou Lo, Faculty of Sciences and Techniques, Cheikh Anta Diop University of Dakar (UCAD), Dakar, Senegal. [03] Aboubaker Chedikh Béye, Faculty of Sciences and Techniques, Cheikh Anta Diop University of Dakar (UCAD), Dakar, Senegal.

The perpendicular polarization of the experimental reflectivity spectra at low temperature of the a-plane oriented ZnO grown on r-plane (011-2) sapphire substrates by plasma-assisted molecular beam epitaxy, shows two types of excitons A and B. The authors used a program based on the theory of the spatial resonance dispersion Hopfield model to fit the free excitons. But the main problem from the investigators were the use of the same Hopfiled model to fit the C free exciton obtained via a parallel polarization. That is why our goal in the present work, is to present our first results about the excitons A & B by using another method taking account the combination of two functions, Lorentzian and Gaussian. We’ve used as a computational method, the stepping by interval method. After calculations, we’ve fitted perfectly the excitons A and B using almost the same physical parameters than the theory of the spatial resonance dispersion Hopfield model. The numerical results show the positions of the A & B excitons energies exactly like the experimental results as displayed in the paper. In comparison, the numerical and experimental results are in good agreement. Otherwise, the same method has been used for beginning new calculations about the C-free exciton obtained from a parallel polarization, the results will be presented in our upcoming paper.

Exciton A and B, Voigt Function, Reflectivity Spectrum, A-plane Oriented ZnO

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