The light response characteristics of oxide-based thin film transistors

We fabricated the inverted-staggered etch stopper structure oxide-based TFT and investigated the characteristics of oxide TFT under the 400 nm wavelength light illumination. When 400 nm light was illuminated, the threshold voltage (V _th) decreased and subthreshold slope (SS) increased at forward sweep, while V _th and SS were not altered when larger wavelength lights, such as 650 nm, 550 nm and 450 nm, were illuminated. At reverse sweep, the transfer curve barely changed even under 400 nm light. Our experimental results support that photo-induced hole carriers are captured by donor-like interface trap and it caused the decrease of V _th and increase of SS. We investigated the interface trap density increases proportionally to the photo-induced hole concentration at active layer.