ZnSnO/Ag/indium tin oxide multilayer films as a flexible and transparent electrode for photonic devices

• ZnSnO (ZTO)/Ag/ITO multilayer films investigated with various Ag layer thickness.
• ZTO/Ag/ITO films have significantly lower sheet resistance than an ITO single layer.
• ZTO/Ag/ITO films have much higher transmittance in the visible spectrum than ITO.
• ZTO/Ag/ITO films show dramatically improved mechanical flexibility compared to ITO.

To replace thick ITO single layer electrodes, ZnSnO (ZTO)/Ag/indium tin oxide (ITO) multilayer films were investigated as a function of Ag layer thickness. The ZTO/Ag/ITO films showed maximum transmittance in the range of 79.4–89.2%, depending on the Ag layer thickness. The relationship between transmittance and Ag thickness was simulated using the scattering matrix method to understand the high transmittance. As the Ag thickness increases from 6 to 14 nm, the carrier concentration increases from 4.12 × 1021 to 1.11 × 1022 cm−3 and the mobility increases from 8.14 to 17.4 cm2/V s. The ZTO (20 nm)/Ag (10 nm)/ITO (30 nm) multilayer films had a sheet resistance of 9 Ω/sq. The ZTO/Ag/ITO multilayer had Haacke’s figure of merit of 28.3 × 10–3 Ω–1. The ZTO/Ag/ITO films deposited on PET substrates showed dramatically improved mechanical flexibility when subjected to bending test compared to 60 nm-thick ITO single layer electrodes.

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