High-k TixSi1−xO2 thin films prepared by co-sputtering method

We report on high-k TixSi1−xO2 thin films prepared by RF magnetron co-sputtering using TiO2 and SiO2 targets at room temperature. The TixSi1−xO2 thin films exhibited an amorphous structure with nanocrystalline grains of 3–30 nm having no interfacial layers. The XPS analyses indicate that stoichiometric TiO2 phases in the TixSi1−xO2 films increased due to stronger Ti–O bond with increasing TiO2 RF powers. In addition, the electrical properties of the TixSi1−xO2 films became better with increasing TiO2 RF powers, from which the maximum value of the dielectric constant was estimated to be ∼30 for the samples with TiO2 RF powers of 200 and 250 W. The transmittance of the TixSi1−xO2 films was above 95% with optical bandgap energies of 4.1–4.2 eV. These results demonstrate a potential that the TixSi1−xO2 thin films were applied to a high-k gate dielectric in transparent thin film transistors as well as metal-oxide-semiconductor field-effect transistors.