Effect of channel widths on negative shift of threshold voltage, including stress-induced hump phenomenon in InGaZnO thin-film transistors under high-gate and drain bias stress

We investigated the degradation of indium-gallium-zinc-oxide (IGZO) thin-film transistors (TFTs) for various channel widths under high-gate and drain bias stress. The threshold voltage of IGZO TFT with wide-channel width (W > 100 mu m) was significantly shifted. This included stress-induced hump-effect in a negative direction after the stress, whereas IGZO TFT with narrow-channel width (W < 100 mu m) shifted in a positive direction. This phenomenon may be attributed to the hole trapping into the back-interface region. In order to enhance the reliability of IGZO TFTs, we developed and verified that the multiple-channel device showed better bias-temperature stability (Delta V-TH: -0.1 V), whereas the single-channel device exhibited a -0.4V Delta V-TH shift. (C) 2012 American Institute of Physics. [doi:10.1063/1.3679109]