Transparent Conductive In and Ga Doped ZnO/Cu Bi-Layered Films Deposited by DC and RF Magnetron Sputtering

In- and Ga-doped ZnO (IGZO) films were deposited on 5 nm thick Cu film buffered poly-carbonate substrates with RF magnetron sputtering and the effects of the Cu buffer layer on the optical and electrical properties of the films were investigated. The IGZO single layer films exhibited an electrical resistivity of 1.2x10(-1) Omega cm while the IGZO/Cu bi-layered films exhibited a lower resistivity of 1.6x10(-3) Omega cm. With respect to optical properties, the optical band gap of the IGZO films appeared to decrease as a result of an increasing carrier concentration due to the Cu buffer layer. In addition, the RMS roughness (8.2 nm) of the IGZO films also decreased to 6.8 nm by a Cu buffer layer in AFM observation. Although the optical transmittance in the range of visible wavelengths was deteriorated by the Cu buffer layer, the IGZO films with a 5 nm thick Cu buffer layer exhibited a higher figure of merit of 2.6x10(-4) Omega compared with the IGZO single layer films due to enhanced optoelectrical performance.