Organic/inorganic hybrid buffer in InGaZnO transistors under repetitive bending stress for high electrical and mechanical stability

We investigated the influence of the multi-layered hybrid buffer consisting of Al2O3 / PA (polyacrylic organic layer) / Al2O3 on the electrical and mechanical properties of amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs). The multi-layered organic/inorganic hybrid buffer has multiple beneficial effects to the flexible TFTs under repetitive bending stress. First, compared to the PA or Al2O3 single-layered buffers, the multi-layered hybrid buffer showed improved WVTR value of 1.1 x 10-4 g/m2day. Even after 40,000 bending cycles, the WVTR value of the hybrid buffer increased only by 17 %, while the WVTR value of the Al2O3 layer doubled after cyclical bending stress. We also confirmed that the hybrid buffer has advantages in mechanical durability of the TFT layers due to the change in the position of the neutral plane, and the strain reduction effect by the PA organic layer. When we fabricate a top-gate a-IGZO TFT with the hybrid buffer layer (HB TFT), the device shows Vth = 0.74 V, μFE = 14.4 cm2/V∙s...