This study examines the chemical and microstructural evolution of In-Ga-Zn-O (IGZO) sol-gel films during post-annealing. Thorough material characterization discloses that the film annealed at 300 degrees C is in an intermixed state of metallorganics and IGZO compound, and that the film annealed at 400 degrees C or higher is a fully transformed IGZO layer with many pores produced by the evaporation of residual organics. Device characterization of transistors fabricated from the films reveals that the electrical characteristics also change sharply over the same temperature range (300-400 degrees C): the 300 degrees C sample exhibits a smooth transfer curve with a very low current while the samples annealed at 350 degrees C or higher display a clear transistor behavior, reflecting the sensitive dependence of the device performance on the chemical state of IGZO sol-gel films. (C) 2013 Elsevier B.V. All rights reserved.