We compared the characteristics of single Ga:ZnO (GZO) and GZO/Ag/GZO multilayer electrodes for source/drain (S/D) contacts in amorphous In–Ga–Zn–O (a-IGZO)-based thin film transistors (TFTs). Due to the existence of a Ag metallic layer between the GZO layers, the GZO/Ag/GZO multilayer electrode exhibited low sheet resistance (3.95ohm/sq.) and resistivity (3.32×10 −5 ohm-cm). The saturation mobility (10.2cm 2 V −1 s −1 ) of the a-IGZO TFT with GZO/Ag/GZO S/D electrodes is much higher than that attained for the a-IGZO TFT with single GZO S/D electrodes (0.7cm 2 V −1 s −1 ) due to the lower resistivity of the GZO/Ag/GZO multilayer S/D electrode. Furthermore, it is expected that the high transparency of the GZO/Ag/GZO multilayer will allow for the possible realization of fully transparent a-IGZO TFTs.