Crystallized Indium-Tin Oxide (ITO) Thin Films Grown at Low Temperature onto Flexible Polymer Substrates

Abstract

Facial off-axis sputtering was used to crystallize in situ-grown ITO films onto a polyethylene terephthalate (PET) substrate at 120°C. The process caused no mechanical damage to the substrate. The 100-nm-thick crystalline ITO films showed a resistivity of about 4.2 × 10−4 Ω-cm and a transmittance of about 83% at a wavelength of 550 nm. The crystallized ITO films showed an improved mechanical durability compared with the amorphous ITO films. The integration of a 30-nm-thick amorphous SiO2 layer onto ITO/PET maintains the resistivity of the ITO films and exhibits an improvement in the transmittance of about 86% compared with the crystalline ITO films. The amorphous SiO2 layer did not adversely affect the mechanical durability of either the crystalline ITO or the amorphous ITO films grown onto the PET. The crystalline ITO films on flexible polymer substrates are indispensable for the mechanical durability of flexible touch screens.