Effect of Bandgap Widening on Negative-Bias Illumination Stress Stability of Oxide Thin-Film Transistors

Oxide semiconductors have been considered as promising channel materials for thin-film transistors (TFTs). However, device reliability against negative-bias illumination stress (NBIS) remains a critical issue that hampers further applications. In this article, the effect of the bandgap widening on the NBIS stability of the oxide TFTs is investigated by simply incorporating the wide bandgap Ga2O3 into In2O3. It is found that there is a tradeoff between the mobility and the NBIS stability. When the Ga2O3 concentration increases from 10 wt% to 45 wt%, the mobility decreases from 22.9 to 5.5 cm(2).V-1.s(-1), while the V-ON shift (Delta V-ON) under 3600 s NBIS improves from -17.8 to -1.6 V. The great improvement of the NBIS stability with increasing Ga2O3 concentration is ascribed to the bandgap widening. After incorporating a certain amount of Ga2O3 into In2O3, the energy difference between the conduction band minimum (CBM) and the V-O state is larger than the maximum photon energy of the white LED, resulting in lesser sensitivity to the incident white light.