Design and characterization of Ga-doped indium tin oxide films for pixel electrode in liquid crystal display

Indium tin oxide (ITO) thin films doped with various metal atoms were investigated in terms of phase transition behavior and electro-optical properties for the purpose of upgrading ITO and indium zinc oxide (IZO) films, commonly used for pixel electrodes in flat panel displays. We explored Ce, Mg, Zn, and Ga atoms as dopants to ITO by the co-sputtering technique, and Ga-doped ITO films (In:Sn:Ga=87.4:6.7:5.9at.%) showed the phase transition behavior at 210°C within 20min with high visible transmittance of 91% and low resistivity of 0.22mΩcm. The film also showed etching rate similar to amorphous ITO, and no etching residue on glass surfaces. These results were confirmed with the film formed from a single Ga-doped ITO target with slightly different compositions (In:Sn:Ga=87:9:4at.%). Compared to the ITO target, Ga-doped ITO target left 1/4 less nodules on the target surface after sputtering. These results suggest that Ga-doped ITO films could be an excellent alternative to ITO and IZO for pixel electrodes in thin film transistor liquid crystal display (TFT-LCD). ► We report Ga-doped In–Sn–O films for a pixel electrode in liquid crystal display. ► Ga-doped In–Sn–O films show phase transition behavior at 210°C. ► Ga-doped In–Sn–O films show high wet etchability and low resistivity.