Effect of oxygen partial pressure contents on the properties of al-doped ZnO thin films prepared by radio frequency sputtering

Al-doped Zinc Oxide (AZO) films were deposited on glass substrates by radio frequency (R.F.) magnetron sputtering technique. The properties of the films were controlled by adjusting the oxygen flow contents as a mixture of Ar and O₂ gases. The structural, electrical and optical properties of the films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), a UV-visible spectrometer, as well as Hall effect measurements. Results revealed that a film deposited with an oxygen partial pressure content of 0% had a hexagonal structure, a strongly preferred orientation with the c-axis perpendicular to the substrate and the lowest resistivity of about 6.9 × 10^-4 Ω cm. The optical transmittance spectra showed more than 80% transmittance in the visible region, and the band gap was found to be direct. Strong violet emission located at 2.96 eV was observed in the AZO films deposited with an oxygen partial pressure content of 0%.