Study On Preparation And Properties Of Solution-processed IGZO Thin Film

The semiconductor industry has become the world’s major industry along with the rapid development of the display technology since the 21 st century. Amorphous oxide materials has been the most promising channel material for the next-generation flat-panel display applications due to its excellent optical and electronic performance.The amorphous Indium-Gallium-Zinc oxide(a-IGZO) semiconductor has the potential to replace traditional silicon-based materials, because it has a series of virtues such as low process temperature and smooth surface,which can meet the demand of large areas of liquid crystal display technology.So it has great significance to study emerging a-IGZO semiconductor.In this paper, effects of deep-ultraviolet(DUV) assisted high pressure at different treatment conditions on microstructure and optical properties of the a-IGZO films fabricated by solution process were characterized with the help of atomic force microscope and spectroscopic ellipsometry. The main contents include:(1) The impacts of DUV assisted high pressure at different annealing temperature on microstructure and optical properties of the a-IGZO films were investigated.The results indicated that when the annealing temperature was increased from 210℃ to 300℃, the optical band gap of the film was increased from 2.97 e V to 3.32 e V, but the thickness of surface roughness was decreased from 22.81 nm to 5.02 nm with the DUV-assistd high pressure treatment. Compared to other post-treatment conditions, such as without UV irradiation at 300℃ under the same pressure or annealing at 350°C, the refractive index of the DUV treated film at 300 ℃ was increased and the surface roughness was decreased obviously.(2) The effects of DUV assisted high pressure at different treatment time on the properties of the a-IGZO thin films were investigated.The results showed that when the annealing time was prolonged from 30 min to 60 min, the thickness of surface roughness was decreased from 5.63 nm to 1.52 nm, but the optical band gap was increased from 3.02 e V to3.26 e V. As the treatment time prolonged,the quality of the film was degenerated.(3) By comparing three-layer structure model with four-layer structure model,the impacts of In concentration on the properties of the a-IGZO thin films were studied.The refractive index of the film analyzed by three-layer structure model was obviously on the low side.Thus the effect of thickness of the surface roughness of should not be neglected.(4) The impacts of In concentration on the properties of the a-IGZO thin films were analyzed by four-layer structure model. Results indicated that when In/(In+Ga+Zn) molar ratio extended from 25% to 62.5%,there was no difference between the thickness of surfaceroughness,the refractive index at 600 nm was decreased from 1.98 to 1.75,and the optical band gap was also reduced from 3.31 e V to 3.23 e VSo. excess In concentration incorporation into IGZO can cause the deterioration of the thin film performances.