Frequency Dependent Degradation and Failure of Flexible a-InGaZnO Thin-Film Transistors Under Dynamic Stretch Stress

Operation of flexible electronic devices is often limited by their degradation and failure under dynamic mechanical stress, where the loading frequency ( ${f}$ ) is found to be a critical factor in this study. The effect of ${f}$ on device degradation and failure of flexible amorphous indium–gallium–zinc–oxide (a-IGZO) thin-film transistors (TFTs) under dynamic stretch stress is investigated in a ${f}$ range of 0.7 to 2.7 Hz. The TFTs exhibit strong ${f}$ -dependent degradation and failure behaviors, featuring larger degradation in off-state current due to mechanical-stress-induced nanocracks originated from the GI/channel interface, as well as more frequent metal wire crack at higher ${f}\text{s}$ . Such a strong ${f}$ -dependency on flexible TFTs in micro-/nano- scales distinguishes it from all previous observations of the opposite or nil ${f}$ -dependency of the fatigue life of conventional bulk or thick-film materials under mechanical stress.