High performance indium gallium zinc oxide thin film transistors fabricated on polyethylene terephthalate substrates

High-performance amorphous ( α − ) InGaZnO-based thin film transistors (TFTs) were fabricated on flexible polyethylene terephthalate substrates coated with indium oxide ( In 2 O 3 ) films. The InGaZnO films were deposited by rf magnetron sputtering with the presence of O 2 at room temperature. The n -type carrier concentration of InGaZnO film was ∼ 2 × 10 17 cm − 3 . The bottom-gate-type TFTs with SiO 2 or SiN x gate dielectric operated in enhancement mode with good electrical characteristics: saturation mobility 11.5 cm 2 V − 1 s − 1 for SiO 2 and 12.1 cm 2 V − 1 s − 1 for SiN x gate dielectrics and drain current on-to-off ratio > 10 5 . TFTs with SiN x gate dielectric exhibited better performance than those with SiO 2 . This is attributed to the relatively high dielectric constant (i.e., high- k material) of SiN x . After more than 500 h aging time at room temperature, the saturation mobility of the TFTs with SiO 2 gate dielectric was comparable to the as-fabricated value and the threshold voltage shift was 150 mV.