Effects of Annealing Temperature on Properties of Al-Doped ZnO Thin Films prepared by Sol-Gel Dip-Coating

Aluminum doped zinc oxide (AZO) thin films have been prepared on the glass substrates (Coming 1737) by sol-gel dip-coating method employing zinc acetate and aluminum chloride hexahydrate for the transparent conducting oxide (TCO) applications. 1 at% Al was doped to the ZnO thin films. The effects of post-heating temperature on the crystallization, optical and electrical properties of the AZO films have been investigated. Experimental results showed that post-heating temperature affected the microstructure, electrical resistance, and optical transmittance of the AZO films. From the X-ray diffraction analysis, all films have hexagonal wurtzite crystal structure. Optical transmittance spectra of the AZO films exhibited transmittance higher than about 80% within the visible wavelength region and the optical direct band gap (E-g) of these films was increased with increasing post-heating temperature. A minimum resistivity of 2.5x10(3) Omega cm was observed at 650 degrees C.