Effects of Electron Irradiation on the Properties of ZnO/Au/ZnO Films Deposited on Poly-Imide Substrates

Transparent and conductive ZnO 50 nm/Au 8 nm/ZnO 50 nm tri-layer films were deposited on poly-imide films by radio frequency (RF) and direct current (DC) magnetron sputtering at room temperature, and then the effect of electron irradiation on the crystallization, electrical resistivity and optical properties of the films was considered with X-ray diffraction, UV-visible spectrometer, Atomic force microscope and Hall measurement system. All the films were deposited at a fixed sputtering power, Ar gas flow rate, and distance between target and substrate, while the post-deposition electron irradiation energy was varied from 300 to 900 eV. The electron irradiated films exhibited a flatter surface than the as deposited films that were not electron irradiated, and the XRD patterns also revealed that the electron irradiated films had larger grain sizes than that of as deposited films. The films electron irradiated at 900 eV also showed a higher visible transmittance of 79.8% and a lower sheet resistance of 56.0 Ω/□. Post-deposition films electron irradiated at 900 eV showed a higher figure of merit of 1.86×10^-3 Ω^-1 than that of the as deposited film of 1.29×10^-3 Ω^-1. The optical band gap was also enhanced by electron irradiation. The films electron irradiated at 900 eV showed a higher optical band gap of 4.07 eV.