Bending Stress Induced Performance Change in Plastic Oxide Thin-Film Transistor and Recovery by Annealing at 300 °C

We report the effect of repeated tensile bending on the performance of amorphous indium-galliumzinc oxide (a-IGZO) thin-film transistors (TFTs) on 15-mu m polyimide substrate. Bending direction is vertical or parallel to the current path in a-IGZO TFT. With increasing bending time, the transfer curve shifts to the negative gate voltage direction. It is noted that the shift is smaller for longer channel length TFT. We performed technology computer aided design simulation for the TFT transfer curves and found that donorlike and acceptorlike states increase, respectively, by 2.5x1017 and 0.4x1017 cm(-3) after 10k bending. The recovery of the transfer curve is studied by thermal annealing of the stressed TFT as a variation of annealing temperature and it is found that the performance can be completely recovered by thermal annealing at 300 degrees C for 1 h.