AZO/Ag/AZO transparent conductive films: correlation between the structural, electrical, and optical properties and development of an optical model

Multilayer transparent electrodes consisting of a tri-layer structure of Al-doped zinc oxide and silver (AZO/Ag/AZO) prepared by inline DC magnetron sputtering at room temperature were investigated. The AZO working gas pressure during deposition was identified as a crucial parameter to influence both the transmittance and sheet resistance of the transparent electrode. By a reduction of the pressure to an optimal value of 0.15 Pa, highest Figure-of-Merit values reported so far for suchlike prepared AZO/Ag/AZO systems could be achieved. In the course of layer characterization, a clear correlation between the coating microstructure and measured electrical and optical properties could be established. Furthermore, we present a model that describes the transmittance spectra of real-structure AZO/Ag/AZO tri-layer systems in a quantitative manner while explicitly considering the specific optical response of the AZO-silver interfaces. Using a generalized Maxwell-Garnett approach with a Gaussian distribution of the Depolarization factors, the interface roughness was described as an effective interfacial layer leading to an improved agreement between measured and simulated spectra. (C) 2016 Optical Society of America