A method for optimizing the electrical conductivity of Al:ZnO TCO films

In this paper, we propose a new strategy for optimizing the conductivity of AZO (ZnO:Al) thin films as transparent conductive oxide (TCOs) based on adapting the atomic percentage of the dopant to the precursor sol concentration. A comparison between the electrical current of pure ZnO and AZO thin films indicated that, the increase in molar concentration of ZnO solution and percentage of Aluminum, respectively up to 1 M and 2 at.%, increased the charge carrier concentration continuously. But a little more increase in both of them actually decreased the conduction. Optical behavior of thin films showed blue shifts in the optical band gap that could be explained by the Burstein-Moss effect and Brus equation. The lattice stress and crystal size of thin films showed that Al+3 ions were properly localized in the ZnO structure prepared with 1 M concentration at 2 at.% Al.