Ta2O5/Al2O3 stacked thin film was fabricated as the gate dielectric for low-voltage-driven amorphous indium-gallium-zinc-oxide (IGZO) thin film transistors (TFTs). The Ta2O5/Al2O3 stacked thin film exhibits a combination of the advantages of Al2O3 and Ta2O5. The IGZO TFT with Ta2O5/Al2O3 stack exhibits good performance with large saturation mobility of 26.66 cm(2) V-1 s(-1), high on/off current ratio of 8 x 10(7), and an ultra-small subthreshold swing (SS) of 78 mV/decade. Such small SS value is even comparable with that of submicrometer single-crystalline Si MOSFET. (C) 2013 Elsevier B.V. All rights reserved.