ENHANCEMENT OF ELECTRICAL CHARACTERISTICS AND STABILITY OF AMORPHOUS In-Ga-Zn-O THIN FILM TRANSISTOR BY O3 TREATMENT

Abstract

The effects of O3 treatment on amorphous indium gallium zinc oxide (a-IGZO) thin film transistors were examined. O3 exposure times from 60 to 600 s were used, with an O3 concentration of 100 g/m3. Compared to untreated a-IGZO TFT, a-IGZO TFTs treated with O3 for 600 s exhibited favorable electrical characteristics such as saturation mobility (µsat) (from 4.54 to 4.85 cm2/Vs), subthreshold swing (S. S) (from 0.41 to 0.33 V/decade) and Ion/off (from 1.23 x 106 to 2.54 x 107). We also found that the O3-treated a-IGZO TFTs show an enhanced instability in threshold voltage (Vth) shift under humidity and negative bias illumination stability (NBIS) conditions. In particular, the Vth shift value of a-IGZO TFT treated with O3 for 600 s shows almost no change (ΔVth < -0.3 V) under NBIS condition for 3 h. Based on these results, we have determined that a-IGZO TFT treated with O3 for 600 s is highly effective in reducing oxygen vacancy [Vo] defects in the a-IGZO channel.