Highly transparent ITO thin films on photosensitive glass: sol–gel synthesis, structure, morphology and optical properties

Conductive and highly transparent indium tin oxide (ITO) thin films were prepared on photosensitive glass substrates by the combination of sol–gel and spin-coating techniques. First, the substrates were coated with amorphous Sn-doped indium hydroxide, and these amorphous films were then calcined at 550∘C to produce crystalline and electrically conductive ITO layers. The resulting thin films were characterized by means of scanning electron microscopy, UV-Vis spectroscopy, X-ray photoelectron spectroscopy and spectroscopic ellipsometry. The measurements revealed that the ITO films were composed of spherical crystallites around 20 nm in size with mainly cubic crystal structure. The ITO films acted as antireflection coatings increasing the transparency of the coated substrates compared to that of the bare supports. The developed ITO films with a thickness of ∼170–330 nm were highly transparent in the visible spectrum with sheet resistances of 4.0–13.7 kΩ/sq. By coating photosensitive glass with ITO films, our results open up new perspectives in micro- and nano-technology, for example in fabricating conductive and highly transparent 3D microreactors.