Mechanical Reliability of Flexible a-InGaZnO TFTs under Dynamic Stretch Stress

Mechanical reliability of flexible amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) is investigated by monitoring the electrical characteristic of TFTs before and after the dynamic stretch stress up to 300k cycles. With increasing the stretch cycles degradation features in a decrease in the on-state current, an increase in the off-state current, but almost no change in the subthreshold region or the threshold voltage. An approximately linear dependence between the on-state current degradation and the stretch force is observed, from which the critical fracture strain of a-IGZO thin film is determined to be 0.42%. It is proposed that a very few number of nanoscaled mechanical-stress-induced cracks, which originate from the interface between the channel and the gate insulator, and develop into both layers, but introduce only insignificant amount of interface defects, can fully explain the observed degradation.