High-performance transparent Li-doped indium-tin-zinc-oxide thin film transistor fabricated by radio frequency magnetron sputtering method

In this work, a Li-doped indium-tin-zinc-oxide (ITZO:Li) thin film transistor was investigated. The ITZO:Li active channel layer was deposited on an SiO2/Si substrate by radio frequency magnetron sputtering at room temperature. The micro structure of the active channel layer is amorphous, as confirmed by X-ray diffraction patterns. The transmittance of the films is above 80% for the visible region (400-700 nm), which indicates excellent optical transparency. The band gap energy of films annealed at 325 °C is about 3.71 eV from the absorption spectrum. It was demonstrated that TFTs fabricated using Li-doped ITZO have fewer oxygen vacancies and enhanced mobility compared to that of undoped ITZO TFTs. The obtained TFTs operate in enhancement mode with a threshold voltage of 0.4 V, a saturation mobility of 39.1 cm2 V−1 s−1, and an on/off current ratio of 8.0 × 106.