High Performance InGaZnO4-based Thin Film Transistors Fabricated at Low Temperature

Thin Film Transistors (TFTs) based on amorphous indium gallium zinc oxide (α-IGZO) were fabricated by RF magnetron sputtering on glass substrates. The TFT device structure was a bottom-gate type, consisting of InZnO as electrodes (gate, source and drain) and two different gate dielectrics (HfO2 and SiNx). The resistivities of the α-IGZO films were controlled from 10-1 to 103 Ω-cm by varying the deposition power, 75W to 300W. TFTs with HfO2 displayed saturation mobility of ~ 7.2 cm2.V-1.s-1, threshold voltage of 0.44V, drain current on-to-off ratio of ~ 105, and subthreshold gate-voltage swing of ~ 0.25 V.decade-1. After 500 hours aging time at room temperature, the threshold voltage for HfO2-IGZO TFTs shifted in the positive direction, while SiNx-IGZO TFTs showed almost constant threshold voltage. The IGZO TFTs based on HfO2 and SiNx gate dielectrics sputtered near room temperature were found to be good candidates for applications on organic flexible substrates