Role of Cu-doping concentration in the synthesis, microstructure and properties of Ag thin films via magnetron co-sputtering method

Abstract

The outstanding optical property and shielding effectiveness of the ultra-thin Ag films make them ideal for use as windows in various applications, such as TV-guided missiles, laser-guided missiles, and shielded cabin. The magnetron co-sputtering method was utilized for depositing ultra-thin Ag films (10 nm) on SiO2 substrates, and their properties were improved by introducing Cu dopants. The influence of Cu concentrations on the structure, optical and shielding performance was analyzed extensively. The study revealed that the addition of a few Cu could inhibit the growth of Ag particles in 3D-island mode, thereby facilitating their nucleation and continuous growth in the plane. The 10 nm Cu-doped Ag thin films by preparing with a Cu doping concentration of 2 mol%, displayed a uniform, continuous and smooth surface morphology whose root-mean-square (RMS) roughness is only 0.88 nm. Furthermore, the films demonstrated excellent optical property with a maximum transmittance of about 79.7% in the visible region. The highest shielding effectiveness (SE) at an optimal concentration of 2 mol% can reach peak value of 36.8 dB. These exceptional properties make Cu-doped Ag films highly valuable and applicable for electromagnetic shielding in transparent windows.