Comparative insights into structural and optical properties of ZnO/Ag/ZnO and Ag/ZnO/Ag ternary layer thin films

The impact of the Ag layer position in ZnO/Ag/ZnO and Ag/ZnO/Ag ternary thin films (thickness: 50 nm) was studied. ZnO was synthesized using atomic layer deposition, while Ag was deposited via direct current (DC) magnetron sputtering. Structural and optical properties were analyzed using GIXRD, SEM, and elemental mapping. Key parameters, including thickness, mass density, crystallite size, dislocation density, and surface roughness, were evaluated. Optical characterization revealed that shifting the Ag layer from the interlayer ZnO/Ag/ZnO to the top and bottom layer Ag/ZnO/Ag reduces the absorption edge from 3.146 to 3.063 eV and the direct optical band gap from 3.24 to 3.14 eV, increasing the Urbach energy from 0.34 to 0.40 eV. These outcomes reveal that the position of the Ag layer significantly affects both structural and optical properties, suggesting potential applications in solar cells, thin-film transistors, and gas sensors.