Effect of Mechanical Strain on Electrical Performance of Flexible P-Type SnO Thin-Film Transistors

This article investigates the effect of mechanical bending strain on the electrical performance and gate-bias stability of flexible p-type tin monoxide (SnO) thin-film transistors (TFTs). The on-polyimide SnO TFTs have an inverted-staggered structure with a back channel passivated by SiN _x and HfO ₂ layers. The as-fabricated linear field-effect mobility, threshold voltage, subthreshold swing, and ON/OFF current ratio are 0.41 cm $^{{2}}\text{V}^{-{1}}\text{s}^{-{1}}$ , 0.74 V, 1.9 V/dec, and $1.1\times 10^{{4}}$ , respectively. The field-effect mobility decreases as the applied tensile strain increases, while it stays almost unaltered when a compressive strain is applied. A prominent increase of the positive-gate-bias-stress-induced threshold voltage shift is observed when the TFT is outwardly bent. The result shows that the mechanical tensile strain has a more significant impact on the electrical performance of p-type SnO TFTs.