ITO films with enhanced electrical properties deposited on unheated ZnO-coated polymer substrates

Indium tin oxide (ITO) films were deposited by radio frequency (rf)-plasma enhanced reactive thermal evaporation (rf-PERTE) at room temperature on intrinsic ZnO/polymer substrates to enhance their electrical and structural properties. The polymer substrate used is polyethylene terephthalate (PET). The thickness of the ZnO films varied in the range 50-150 nm. The average thickness of the ITO films is of about 170 nm. Results show that ITO deposited on bare PET substrates exhibit: an average visible transmittance of about 85% and an electrical resistivity of 5.6 × 10−2 Ω cm. ITO on ZnO/PET substrates show the optical quality practically preserved and the resistivity decreased to a minimum value of 1.9×10−3 Ω cm for ZnO layers 125 nm thick. The electrical properties of ITO on ZnO/PET are largely improved by the increase in carrier mobility.