Improved Electrical Properties of Indium Gallium Zinc Oxide Thin-Film Transistors by AZO/Ag/AZO Multilayer Electrode

We fabricated an a-IGZO thin film transistor (TFT) with AZO/Ag/AZO transparent multilayer source/drain contacts by rf magnetron sputtering. a-IGZO TFT with AZO/Ag/AZO multilayer S/D electrodes (W/L = 400/50 µm) showed a subs-threshold swing of 3.78 V/dec, a minimum off-current of 10-12 A, a threshold voltage of 0.41 V, a field effect mobility of 10.86 cm2/Vs, and an on/off ratio of 9ƒ 109. From the ultraviolet photoemission spectroscopy, it was revealed that the enhanced electrical performance resulted from the lowering of the Schottky barrier between a-IGZO and Ag due to the insertion of an AZO layer and thus the AZO/Ag/AZO multilayer would be very appropriate for a promising S/D contact material for the fabrication of high performance TFTs.