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 layer 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°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 × 10-3 Ω&middotcm under doping concentration 1% (mole fraction), annealing temperature 500°C and deposition layers 10.