Influence of substrate temperature on the optical properties of ZnO thin films

The ZnO thin films were deposited at different substrate temperatures by ultrasonic spray and spray pyrolysis techniques. In this paper we present a new approach to control the optical gap energy of ZnO thin films by varying the substrate temperature. The model proposed to calculate the band gap energy with the Urbach energy was investigated. The relation between the experimental data and theoretical calculation suggests that the band gap energies are predominantly estimated by the Urbach energies, film transparency and substrate temperatures. The measurements by these proposals model are in qualitative agreements with the experimental data, which the correlation coefficients values were varied in the range 0.96 – 0.99999, indicating high quality representation of data based on Eq. (2), so that the relative errors of all calculations are smaller than 4%.