High Performance of a-IZTO TFT by Purification of the Semiconductor Oxide Precursor

The effect of purification of oxide semiconductor precursor on the performance of amorphous indium-zinc-tin oxide (a-IZTO) thin-film transistors (TFT) using a high-k zirconium oxide (ZrOx) gate insulator is reported. By purification of IZTO precursor, the saturation mobility (mu(sat)) of the IZTO TFT increases from 2.84 to 9.50 cm(2) V-1 s(-1), threshold voltage (V-TH) decreases from 0.63 to 0.51 V, subthreshold swing (SS) decreases from 169 to 87 mV dec(-1), hysteresis voltage (V-H) reduces from 0.05 to 0 V, and an ON/OFF current ratio (I-ON/I-OFF) increases from approximate to 10(7) to approximate to 10(8). These improvements are due to the reduction in the impurities and oxygen vacancies at the bulk of IZTO and a-IZTO/ZrOx interface as well. The significant reduction of broad absorbance peak centered at 553 nm can be found by purification, which is direct evidence of the reduction of the impurity concentration in the metal oxide precursor solution.