Densification effects on solution-processed indium-gallium-zinc-oxide films and their thin-film transistors

Abstract

We report the effects of high-pressure annealing (HPA) on solution-processed InGaZnO (IGZO) thin-film transistors (TFTs). HPA increased the density of IGZO films. In particular, annealing in O2 at 1.0 MPa and 350 °C resulted in a high-density and low-porosity IGZO film, as characterized using X-ray reflectivity (XRR) and ellipsometry measurements. This was attributed to the oxidative and compressive effects on the oxygen-deficient solution-processed IGZO film. TFTs annealed in O2 at 1.0 MPa and 350 °C exhibited an increase in the field-effect mobility by a factor of approximately five compared with TFTs annealed in air at 0.1 MPa and 350 °C. Furthermore, improvements in reliability under negative and positive bias stresses were also observed following HPA.