Improving the electrical properties and stability of amorphous indium gallium zinc oxide thin-film transistors through ozone treatment

Abstract

The effect of ozone (O3) treatment on amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs) was investigated. The study utilized O3 exposure durations ranging from 60 to 600 s, with a concentration maintained at 100 g/m3. The results indicated that a-IGZO TFTs subjected to O3 treatment for 600 s exhibited enhanced electrical characteristics in comparison to their untreated counterparts. Specifically, there was an increase in saturation mobility (µsat) from 4.54 to 4.85 cm2/Vs, a decrease in subthreshold swing (S.S) from 0.41 to 0.33 V/decade, and an improvement in the on/off current ratio (Ion/off) from 1.23 × 10⁶ to 2.54 × 10⁷. Furthermore, the O3-treated a-IGZO TFTs demonstrated greater stability in threshold voltage (Vth) shifts when subjected to humidity and negative bias illumination stability (NBIS) conditions. Notably, the Vth shift for the a-IGZO TFT treated with O3 for 600 s remained relatively stable (ΔVth < – 0.3 V) under NBIS conditions over 3 h. These findings suggest that the 600-s O3 treatment highly effective in reducing oxygen vacancy (VO) defects within the a-IGZO channel.