Simultaneous Improvement in the Corrosion Resistance and Visible Transparency of ZnO/Cu/ZnO Transparent Heaters with Reactively Sputtered Al2O3 Layers

Abstract

In this study, we report a methodology that simultaneously improved the corrosion resistance and visible transparency of ZnO/Cu/ZnO transparent heaters with the addition of reactively sputtered Al2O3 layers. To assess corrosion resistance, ZnO and Al2O3 layers with thicknesses in the range of 0-20 nm were deposited onto 20 nm-thick Cu layer, and the corrosion behavior of the underlying Cu layers was investigated by evaluating the sheet resistance change in an 85 °C/85% humidity test. While the 20 nm-thick ZnO layer was not an effective moisture barrier, showing a sheet resistance increase of more than 50% after 10,000 m, the sheet resistance of the Cu layer below the 5 nm-thick Al2O3 layer did not show an observable increase for equal duration. Optical transmittance was also investigated by constructing glass/ZnO/Cu/ZnO/Al2O3 structures with varying thicknesses for the top ZnO and Al2O3 layers, in the range of 10-30 and 10-60 nm, respectively The thicknesses of the bottom ZnO and Cu layers were fixed at 30 nm and 10 nm. The results revealed that the average visible light transmittance of the ZnO/Cu/ZnO/Al2O3 structure increased by 2.5% over the optimized ZnO/Cu/ZnO structure.