Post-treatments of Al-doped ZnO films fabricated by sol-gel method were studied in condition of annealing in air, vacuum and protective ambient, as well as the follow-up Ai(+) sputtering cleaning. The effect of annealing pressure on resistivity of AZO films was investigated from 10(5) to 10(-4) Pa, where the resistivity decreased four orders of magnitude as the pressure decreased and approached to its minimum at 10 Pa. It was observed that the main decreasing of resistivity occurred in a very narrow range of middle vacuum (between 100 and 10 Pa) and high vacuum was dispensable. The XRD and XPS characterizations demonstrated that the radical increasing of oxygen vacancy, Zn interstitial and substitution of Al3+ for Zn2+ under middle vacuum were responsible for the significant enhancement of conductivity. The follow-up Ar+ sputtering cleaning can further decrease the resistivity through removing the chemisorbed oxygen on film surface and grain boundaries, meanwhile fulfil the surface texture process, and thus improve both electrical and optical performances for applications. (C) 2016 Elsevier B.V. All rights reserved.