Effect of charge trapping/detrapping on threshold voltage shift of IGZO TFTs under AC bias stress

摘要

We have investigated the dependency of alternating current (AC) stress duty ratio on the stability of indium-gallium-zinc-oxide (IGZO) thin-film transistors (TFTs). As the duty ratio increases from 0.25 to 0.75, threshold voltage (V TH) shift under the AC gate bias stress was increased from 4.10 V to 5.01 V, without degradation of subthreshold slope and mobility. The dominant mechanism of V _(TH) shift was considered the charge trapping and V _(TH) shift along with time was well fitted to a stretched-exponential model. The V _(TH) shift was suppressed with a reduction of trap density by employing N _2O plasma treatment on the gate insulator.