Al-doped zinc oxide (AZO) thin films were deposited onto flexible polyethylene terephthalate substrates, using the radio frequency (RF) magnetron sputtering process, with an AZO ceramic target (The Al(2)O(3) content was about 2 wt.%). The effects of the argon sputtering pressure (in the range from 0.66 to 2.0 Pa), thickness of the Al buffer layer (thickness of 2, 5, and 10 nm) and annealing in a vacuum (6.6 x 10(-4) Pa), for 30 min at 120 degrees C, on the morphology and optoelectronic performances of AZO films were investigated. The resistivity was 9.22 x 10(-3) Omega cm, carrier concentration was 4.64 x 10(21) cm(-3), Hall mobility was 2.68 cm(2)/V s and visible range transmittance was about 80%, at an argon sputtering pressure of 2.0 Pa and an RF power of 100 W. Using an Al buffer decreases the resistivity and optical transmittance of the AZO films. The crystalline and microstructure characteristics of the AZO films are improved by annealing. (C) 2011 Elsevier BM. All rights reserved.