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

High-k Ti_1−xSi_xO₂ 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 Ti_1−xSi_xO₂ 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 Ti_1−xSi_xO₂ 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.