Thickness dependent properties of Al-doped ZnO film prepared by using the pulsed DC magnetron sputtering with cylindrical target

Various thicknesses of Al-doped ZnO (AZO) films were deposited on glass substrate using pulsed dc magnetron sputtering with a cylindrical target designed for large-area high-speed deposition. The structural, electrical, and optical properties of the films of various thicknesses were characterized. All deposited AZO films have (0002) preferred orientation with the c-axis perpendicular to the substrate. Crystal quality and surface morphology of the films changed according to the film thickness. The samples with higher surface roughness exhibited lower Hall mobility. Analysis of the measured data of the optical band gap and the carrier concentration revealed that there were no changes for all the film thicknesses. The optical transmittances were more than 85% regardless of film thickness within the visible wavelength region. The lowest resistivity, 4.13 × 10^-4 Ω ·cm^-1, was found in 750 nm films with an electron mobility (μ) of 10.6 cm²V^-1s^-1 and a carrier concentration (n) of 1.42 × 10²¹ cm^-3.