Investigation of conductive and transparent ITO/Ni/ITO multilayer films deposited by a magnetron sputter process

Transparent conducting ITO/Ni/ITO films were deposited by RF magnetron sputtering of Sn-doped In₂O₃ and DC magnetron sputtering of Ni on unheated polycarbonate substrates. Ni interlayers with thicknesses of 5, 10, and 20 nm were used as intermediate metallic layers.Changes in the work function and optical, electrical and structural properties of the films were examined with respect to Ni layer thickness. The work function was measured to be about 4.5 eV and was found to be independent of Ni layer thickness. However, the structural, optical, and electrical properties of the films were influenced by the Ni thickness. As-deposited ITO single layer films showed In₂O₃ diffraction peaks for the (2 2 2) and (4 0 0) planes, while after insertion of the Ni layer between ITO films, these diffraction peaks disappeared. The electrical resistivity decreased with the Ni intermediated film and the optical transmittance also decreased due to increased optical absorption. The figure of merit reached a maximum of 2.0 × 10⁻³ Ω⁻¹ for a 5 nm-thick inserted Ni film, which is greater than the value for as-deposited ITO films.