Modification of surface morphology of sputtered AZO films with the variation of the oxygen

Al doped Zinc Oxide (AZO) thin films were deposited on glass substrates using DC magnetron sputtering method at different oxygen argon gas ratio. Effects of oxygen gas concentration ratio on structural, electrical and optical properties of the deposited AZO thin films were investigated by X-ray diffraction (XRD), atomic force microscope (AFM), Hall effect, ellipsometry and UV-visible spectrophotometer measurements. Results established that the films have strong c-axis orientation perpendicular to the substrate surface and exhibit better crystallinity as oxygen argon ratio increases. The lowest resistivity of 4.83 × 10−4 Ω-cm was obtained without using oxygen in the gas mixture. The average optical transmission increased from 73% to 80% in the wavelength range of 350-1100 nm and ultraviolet absorption edge shifts toward longer wavelength with the increase of oxygen argon ratio. Higher value of refractive index and a strong orange-red deep level emission was spotted in AZO thin films deposited with higher O2/Ar ratio.