The Effect of the Doping Levels on Urbach Energy of the Zinc Oxide Thin Films

Abstract

Within the proposed model, the calculated Urbach energy of the undoped and Bi-, Sn-and Fe-doped ZnO thin films is studied as a function of doping levels. The Bi-, Sn-and Fe-doped ZnO films were deposited by spray depositions at various conditions such as ZnO-based solution molarity and doping levels. The measurements by means of this proposed model are found to be in a qualitative agreement with the experimental data with high correlation coefficients of 0.92-0.98. The Urbach-energy calculations for doped films are improved to maximum enhancement corresponding to minimum error, which is found for the Sn-and Fe-doped ZnO films to be 5.5 and 5.1%, respectively.