ITO/metal/ITO multilayer structures based on Ag and Cu metal films for high-performance transparent electrodes

Transparent conductive indium tin oxide (ITO)/metal/ITO multilayer electrodes have been prepared by sputtering at room temperature. Ag and Cu thin films with thickness ranging from 5 to 35 nm have been used as intermediate metal layer, between ITO coatings of about 30 nm thickness. Evolution of the optical and electrical characteristics of the multilayers as a function of each metal film thickness has been analyzed. High-quality transparent electrodes have been obtained, with sheet resistance below 6 Ω/sq for Ag film thickness above 10 nm or Cu film thickness above 16 nm. These multilayers also showed high transmittance in the visible spectral range, above 90% by discounting the glass substrate, with a maximum that is located at lower wavelength for Ag-based electrodes than for the Cu-based ones. After heating at 350 °C in flowing nitrogen, some improvement in the optoelectronical characteristics of the multilayer electrodes has been achieved that is related to the structural improvement of the ITO components.