AZO (2% Al doped ZnO) thin films, with thicknesses of 30 nm (AZO30), 50 nm (AZO50) and 400 nm (AZO400), deposited onto glass substrate by RF magnetron sputtering were subjected to annealing at a temperature of 700K for a period of 90min in air. As-deposited AZO30 and AZO50 samples were almost amorphous, with very small grains. After annealing, a crystallization process from amorphous to crystalline phase occurred. X-ray diffraction and scanning electron microscopy analyses showed a polycrystalline structure and a preferred orientation of the crystallites for the obtained thin films. Atomic force microscopy measurements indicated roughness values of 0.7 nm for AZO30, 1.4 nm for AZO50 and 18 nm for AZO400 annealed samples. Optical transmittance investigations of the layers in the 0.2-1.2 pin wavelength range showed a high transmission in the visible and near infrared range, as well as values between 3.36 and 3.45 eV for the optical bandgap. The present simple processing route is useful for device applications of transparent conductive oxides. (C) 2015 Elsevier B.V. All rights reserved.