Study of structural and electrical properties of zinc oxide and Al-doped zinc oxide thin films deposited by DC sputtering

Transparent conducting aluminum-doped and undoped ZnO thin films have been deposited by direct current (DC) sputtering technique from ZnO target onto glass substrate at room temperature and 400 °C. X-ray diffraction analysis shows that all films have a preferential growth along the c-axis of the hexagonal structure. The average grain size increases with the increasing deposition temperature and the doping of thin films. Analysis with AFM shows an improvement of the surface with the doping of thin films and deposition temperature. The root main square (RMS) surface roughness increases with deposition temperature. Al-doped ZnO (AZO) thin films have a lower electrical resistivity than that of ZnO thin films. 1/f noise measurement shows that ZnO thin film is more homogeneous than that of AZO.