Structural and opto-electrical properties of Al doped ZnO sputtered thin films

Transparent and conductive aluminum-doped zinc oxide (AZO) thin films with high preferential c-axis orientation have been deposited on glass substrates by radio frequency magnetron sputtering method of ZnO and DC magnetron sputtering of Al. Structural, surface morphology, optical and electrical properties of ZnO thin films were studied by X-ray diffraction, scanning electron microscope, ultraviolet-visible spectrophotometer, surface plasmon spectroscopy and Hall effect measurements. The results show that AZO films are polycrystalline and exhibit the hexagonal wurzite crystal structure with a preferred orientation along (002) direction. When DC sputtering power supplied to Al target increases, the crystallinity decreases while the electrical resistivity increases. The average measured transmittance exceeded 75 % in the visible range for all AZO thin films. The band gap values increase with decreasing the Al concentrations.