Compositional analysis and optical properties of Ag-doped ITO films

ITO and Ag-ITO composite films were deposited on glass substrates by DC magnetron sputtering. Scanning electron microscope images indicated that Ag existed in the form of nanoparticles. X-ray photoelectron spectroscopic analysis illustrated that both Ag doping and heat treatment had obvious influence on the composition and element chemical state of the films. Ag doping dramatically decreased the transmittance of the film. But after being annealed, Ag-ITO films exhibited the high average transmittance of 80–90% in visible wavelength range. By using the spectroscopic ellipsometry optimization, the optical constants were extracted from the transmittance spectra. The results suggested the potential use of Ag-ITO films for antireflection coating system.

► ITO properly doped silver showed much higher refractive index than that of pure ITO, the significance of which is that antireflection coating could be made by ITO films in series.
► Composition and chemical states of elements varied after Ag doping and annealing, which can be explained by experimental evidences.
► ITO film doped with Vol. 0.3% Ag shows the high transmittance and the lowest resistivity after annealing at 400 °C.