Physical characterization of amorphous In-Ga-Zn-O thin-film transistors with direct-contact asymmetric graphene electrode

High performance a-IGZO thin-film transistors (TFTs) are fabricated using an asymmetric graphene drain electrode structure. A-IGZO TFTs (channel length = 3 μm) were successfully demonstrated with a saturation field-effect mobility of 6.6 cm²/Vs without additional processes between the graphene and a-IGZO layer. The graphene/a-IGZO junction exhibits Schottky characteristics and the contact property is affected not only by the Schottky barrier but also by the parasitic resistance from the depletion region under the graphene electrode. Therefore, to utilize the graphene layer as S/D electrodes for a-IGZO TFTs, an asymmetric electrode is essential, which can be easily applied to the conventional pixel electrode structure.