Stage-by-stage formation of superficial nanostructures in ITO films reduced by H 2 -GD at low temperature (100 °C) for applications on plastic substrates.

The formation of superficial nanostructures (SNs) in reduced indium tin oxide (ITO) thin films by H2-Glow discharge (GD) at a low reduction temperature (Tr=100 °C) was investigated. Sputtered ITO films deposited at low (Td=100 °C) and high (Td=300 °C) temperatures were reduced using this low-temperature process. Scanning electron and atomic force microscopy were applied to study the evolution of the nanostructural features and three stages were identified: emerging/densification, coalescence, and depletion stages. The structural characteristics of the SNs were characterized by grazing incidence and conventional θ/2θ X-ray diffractions showing that at Tr=100 °C, the reduction process was limited to the surface region in which the ion bombardment had influence. The mean diameter of the SNs in ITO deposited on the glass substrate was controlled from ~10–90 nm and the SNs densities, d, were obtained from ~109–1011 SNs/cm2. Finally, the superficial nanostructures were successfully formed in ITO films deposited on flexible polyethylene naphthalate (PEN) substrates. It was demonstrated that, on these substrates, is possible to obtain a uniform distribution in the size and density of the SNs, with =9.5–20.7 nm and d=2.66×1011–4.20×1010 SNs/cm2.