Impacts of substrate heating schemes on characteristics of amorphous indium-gallium-zinc-oxide (a-IGZO) TFTs fabricated on flexible substrates

The impacts of substrate heating scheme on the characteristics of amorphous indium-gallium-zinc-oxide (a-IGZO) TFTs fabricated on flexible PEN substrate are investigated. For the a-IGZO TFTs fabrication, the substrate is heated during the a-IGZO deposition, pre-annealing in N₂ is also conducted before passivation layer deposition, and post-annealing is done at last. The results show that the pre-annealing and post-annealing improve the hysteresis characteristics, but degrade the field-effect mobility μ_FE and subthreshold swing SS. In contrast, both the hysteresis voltage V_h and the electrical performance are enhanced when the a-IGZO is sputtered with substrate temperature of 150°C. The major performance parameters μ_FE, SS, and V_h are 7.34 cm²/Vs, 0.438 V/dec, and 2.3 V, respectively.