High Performance InGaZnO_4-based Thin Film Transistors Fabricated at Low Temperature

摘要

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 (HfO_2 and SiN_x). The resistivities of the a-IGZO films were controlled from 10~(-1) to 10~3 Ω-cm by varying the deposition power, 75W to 300W. TFTs with HfO_2 displayed saturation mobility of～7.2 cm~2V~(-1)s~(-1), threshold voltage of 0.44V, drain current on-to-off ratio of～10~5, and subthreshold gate-voltage swing of～0.25 V.decade~(-1). After 500 hours aging time at room temperature, the threshold voltage for HfO_2-IGZO TFTs shifted in the positive direction, while SiN_x-IGZO TFTs showed almost constant threshold voltage. The IGZO TFTs based on HfO_2 and SiN_x gate dielectrics sputtered near room temperature were found to be good candidates for applications on organic flexible substrates.