Properties of high-k Ti1−xSixO2 gate dielectric layers prepared at room temperature

High-k Ti1−xSixO2 gate dielectric layers were prepared at room temperature by RF magnetron sputtering using SiO2 and TiO2 targets to investigate their applicability to transparent thin-film transistors as well as metal–oxide–semiconductor field-effect transistors. Based on XRD and XPS analyses, it was found that, regardless of the deposition time, the Ti1−xSixO2 gate dielectric layers had more stable Si-based phases with stronger Si–O bonds with increasing SiO2 RF power. As SiO2 RF power increased, the capacitance of the dielectric layers decreased due to the higher fraction of the Si-based phases, and the leakage current decreased, dominantly because of the decrease in oxygen vacancies due to the formation of stoichiometric SiO2. The Ti1−xSixO2 gate dielectric layers exhibited high transparency above 80% and moderate bandgap of 4.1–4.2 eV, which can be applied to transparent thin-film transistors.