A Study the Calculation of the Optical Gap Energy and Urbach Energy in the Semiconductor Doping

Abstract

We investigated the optical properties of pure and Aluminum doped zinc oxide thin films as the n-type semiconductor. In this paper we have focused our attention on the creation of a new approach to calculate the optical gap and Urbach energies, these correlations based on experimental data were published previously in the literatures. The thin films were deposited at different precursor molarities by ultrasonic spray and spray pyrolysis techniques. The calculation by these proposal models of the band gap and the Urbach energies of undoped and doped ZnO thin films were studied. The relation between the experimental data and theoretical calculation with precursor molarities suggests that the band gap and/or the Urbach energies are predominantly estimated by the band gap and/or the Urbach energies and the concentrations of ZnO solution and Al doping. The measurements by these proposals models are in qualitative agreements with the experimental data that have been reliable in this work, at this point the correlation coefficients value was estimated of 0.99, and thus we have found that the relative errors of all calculation are smaller than 4 % for optical band gap and 20 % for Urbach energy. The best estimated results were obtained for Al doped ZnO thin films; with minimum relative errors values were limited to 3.6 and 8.3 % for the band gap and the Urbach energies, respectively. This is the approach adopted to improve the band gap energy for less disorder of ZnO thin films after doping. Stoichiometric Al doped ZnO films are highly transparency and good optical band gap.