Improvement and optimization of AZO/Ag/Ni/AZO multilayer transparent conductive films

Transparent conductive oxide (TCO) thin films are widely used in displays, photovoltaic devices, and transparent antennas. Indium tin oxide (ITO), with a resistivity below 10−5 Ω cm and a transmittance above 90%, remains the preferred material. However, the scarcity of indium and limited mechanical flexibility of ITO necessitate alternative TCOs. In this study, AZO/Ag/Ni/AZO multilayers were fabricated by introducing a Ni interlayer to mitigate the degradation caused by Ag diffusion and oxidation. The effects of Ni deposition parameters on the electrical, optical, and structural properties were systematically examined. Conventional AZO/Ag/AZO structures exhibited resistivity and transmittance of 12.15 × 10−5 Ω cm and 90.1%, respectively, whereas a 2 nm Ni layer deposited at 0.08 nm/s yielded resistivity and transmittance of 3.03 × 10−5 Ω cm and 74.7%, respectively, thereby demonstrating superior performance. Auger electron spectroscopy confirmed that the Ni interlayer effectively suppressed the diffusion and oxidation of Ag. X-ray diffraction and atomic force microscopy further revealed that Ni deposition strongly influenced the crystallinity and morphology of ZnO. Notably, slow deposition promoted the defects and nanoscale voids in the Ni layer, reducing the density and increasing the oxygen permeability. These results indicate that optimizing the Ni thickness and deposition rate is essential for enhancing barrier performance against Ag oxidation and diffusion. Moreover, further reduction in resistivity is required to utilize these multilayers in advanced applications, such as transparent antennas.