Correlation between the electrical and structural properties of aluminium-doped ZnO thin films obtained by direct current magnetron sputtering

High quality Aluminium-doped Zinc Oxide (AZO) films have been obtained by suitably controlling the magnetron sputtering parameters and the substrate temperature. The X-ray diffraction studies showed that a transition of orientation from (002) plane to (103) plane, versus substrate temperature. The surface morphology characterized by scanning electron microscopy and atomic force microscopy exhibited a dense and compact structure at higher temperature. For 200 nm thick AZO films deposited at temperature 530°C, using a ZnO target with an Al2O3 content of 3 wt%, the lowest electrical resistivity is 6.8×10−4 Ω.cm and transmittance is over 85% in the visible spectral region. The conductivity improvement of AZO films was closely related to the crystallanity characterized by the (103) orientation and the densely packed structure.