Deposition of aluminum-doped zinc oxide films by RF magnetron sputtering and study of their structural, electrical and optical properties

Highly oriented undoped and aluminum-doped ZnO (AZO) films in the (002) direction were prepared by RF magnetron sputtering on glass substrates with specifically designed ZnO targets containing different amounts of Al(OH)(3) powder as doping source. A systematic study of the influence of deposition parameters such as Al(OH)(3) content in the target, the target-substrate distance (D-ts), deposition time and substrate temperature on the structural, electrical and optical properties of the as-grown AZO films was carried out. XRD shows that AZO (002) crystal grew parallel to the substrate. With increasing D-ts the growth rate increased, while the substrate temperature did not affect the growth rate. The as-grown AZO films not only have an average transmittance of > 85% in the visible region, but also have an optical bandgap between 3.2 and 3.64 eV, depending on the sputtering parameters. The resistivity of the film deposited at D-ts=45 mm from a 4 wt.% Al(OH)(3)-doped ZnO target was approximately 9.8 x 10(-2) Omega cm, showing semiconductor properties. (C) 2003 Elsevier Science B.V. All rights reserved.