Influence of gate dielectric and its surface treatment on electrical characteristics of solution-processed ZnO transistors

We report how interface treatments affect electrical performance, including subthreshold characteristics, in solution-processed transparent metal oxide thin-film transistors (TFTs) with SiO₂ and SiN_x gate dielectrics. Ultra-violet (UV) ozone treatment and O₂ plasma treatment are carried out as a surface treatment of the interface between a spin-coated zinc oxide (ZnO) layer and a gate dielectric. With the SiO₂ dielectric, UV ozone treatment dominantly affects subthreshold characteristics, while O₂ plasma treatment produces enhanced mobility and lower threshold voltage shift. With the SiN_x dielectric, every electrical parameter including mobility, threshold voltage shift, and subthreshold characteristics is enhanced by O₂ plasma treatment. Our experimental results demonstrate that interface engineering treatments variously influence the electrical performance in solutionprocessed ZnO TFTs.