Microstructure, optical and electrical properties of ZnO:Al film prepared by sol-gel method

Aluminium. doped zinc oxide (AZO) polycrystalline thin films were prepared on optical glass substrates by sol-gel dip-coating process. The effects of aluminium concentration, deposited layear number and annealing temperature on the microstructure, optical and electrical properties of the films were investigated by X-ray diffraction (XRD), spectrophotometric analysis (UV-Vis), scanning electron microscopy (SEM) and electrical resistance measurement. The results showed that with increasing the annealing temperature from 300 to 500 degrees C, the film grew more preferentially along the (001) plane of the film, the grain size increased, the transmittance also became higher and the electrical resistivity decreased. X-ray diffraction analysis revealed the film consists of single-phase ZnO with hexagonal wurtzite structure. Average optical transmittance of the film is more than 90% in the visible light region and electrical resistivity is as low as 3.2 x 10(-3) Omega-cm under doping concentration 1% (mole fraction), annealing temperature 500 degrees C and deposition layers 10.