Thickness dependence of the properties of transparent conducting ZnO:Zr films deposited on flexible substrates by RF magnetron sputtering

Transparent conducting zirconium-doped zinc oxide (ZnO:Zr) thin films with high transparency, low resistivity and good adhesion were successfully prepared on water-cooled flexible substrates (polyethylene glycol terephthalate, PET) by RF magnetron sputtering. The structural, electrical and optical properties of the films were studied for different thicknesses in detail. X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed that all the deposited films are polycrystalline with a hexagonal structure and a preferred orientation perpendicular to the substrate. The lowest resistivity achieved is 1.55 x 10(-3) Omega center dot cm for a thickness of 189 nm with a Hall mobility of 17.6 cm(2)/(V"s) and a carrier concentration of 2.15 x 10(20) cm(-3). All the films present a high transmittance of above 90% in the wavelength range of the visible spectrum.