Effect of contact material on amorphous InGaZnO thin-film transistor characteristics

Amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs) having several metals, namely Ag, Ti, and Mo, as the source and drain electrodes were characterized. TFTs with Ti and Mo electrodes showed drain current-gate voltage characteristics without fluctuation. However, TFTs with Ag electrodes indicated a low noisy on-state current at a large channel length under a low drain-source voltage condition. The source and drain resistances [Rs/d (O)] of the TFTs with each of the three metals were calculated from the IDS-VGS characteristics. The Rs/d values of the Ag, Ti, and Mo samples reached 4 x 10(4), 2 x 10(4), and 1 x 10(4) Omega, respectively. This implies that a spatial potential barrier exists at the a-IGZO/Ag interface and that the resistance of the potential barrier changes with the application of gate voltage. (c) 2014 The Japan Society of Applied Physics