A low resistivity copper (Cu) film was used as a source/drain contact layer to fabricate high performance amorphous In-Zn-Sn-O (a-IZTO) thin-film transistors (TFTs). The calcium (Ca)-doped Cu films greatly simplified the conventional Cu/diffusion barrier stack structure and process, which allowed the production of promising aIZTO TFTs with a saturation mobility of 22.8 cm(2)/Vs and an ION/OFF ratio of 108. Furthermore, the a-IZTO TFTs with the Ca -doped Cu contact exhibited better gate bias thermal stress-induced stabilities than those with the pure Cu contact. This was attributed to the effective formation of a self-diffusion CuO. barrier at the Cu/IZTO interfaces. (C) 2017 Elsevier B.V. All rights reserved.