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

摘要

High-performance amorphous (α-) InGaZnO-based thin film transistors (TFTs) were fabricated on flexible polyethylene terephthalate substrates coated with indium oxide (In_2O_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.