Effects of post-deposition heat treatment on the microstructure and properties of Al-doped ZnO thin films prepared by aqueous phase deposition

► Transparent conducting Al-doped ZnO films were prepared by aqueous phase deposition. ► By a two-step heat treatment, the resistivities of the films declined considerably. ► Reducing atmosphere is beneficial for the grain sizes and carrier concentrations. ► The electrical resistivity was declined steadily with heat treatment temperature. ► Scattering within grains is dominant due to the small mean free path of the carriers.