Preparation of ZnO:Al (ZAO) transparent conductive thin films by using the sol-gel method with orthogonal testing
ZHOU MingGe ZHAN KeTao (School of Science, Beijing University of Chemical Technology, Beijing 100029, China)
ZnO∶Al (ZAO) transparent conductive thin films have been prepared by a sol-gel method. The films were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (SEM), UV-Vis spectrophotometry and a four-point probe instrument. The effects of factors such as sol concentration, Al dopant concentration (mole fraction) and annealing temperature on the resistivity of the ZAO film were studied. The results showed that with increasing sol concentration and Al dopant concentration, the resistivity at first decreased and then increased, whereas it decreased monotonically with increasing temperature. The optimal preparation conditions obtained by orthogonal testing are as follows: (1) sol concentration 0.8 mol/L; (2) Al dopant concentration 1.0%; (3) annealing temperature 550 ℃. Under the optimal conditions, the resulting ZAO film had a polycrystalline hexagonal wurtzite structure with a resistivity of 1.275×10-3 Ω·cm and average optical transmittance of 84%.