Optimization of ZnO/Ag/ZnO Transparent Conductive Electrodes Fabricated by Magnetron Sputtering

The critical role of the thicknesses of the top and bottom oxide layers, as well as Ag layer, in ZnO/ Ag/ZnO transparent conductive electrodes were investigated. The Ag forms a nearly continuous layer at the thickness of 8 nm, at which the Ag sheet resistance of 8.0 Omega/Sq. is lower than the typical criteria of 10 Omega/Sq. By making independent changes in the thickness of the top and bottom ZnO layers, which serve as antireflection layers, it was found that the top ZnO layer thickness has a dominant impact, with the bottom ZnO layer thickness contributing a less but still significant amount. The optimized thicknesses for the top and bottom ZnO layers were found to be 40 and 20-30 nm, respectively, resulting in a peak transmittance of 97.1% and average visible light transmittance of 90.8%. According to the Haccke figure of merit (phi(H )= T-ava(10)/R-s), the value for the optimized ZnO/Ag/ZnO electrode was 0.048, which is highly competitive for transparent conductive electrodes for future optoelectronic devices.