Thickness and microstructure effects in the optical and electrical properties of silver thin films

Abstract

The optical and electrical response of metal thin films approaching thicknesses in the range of the electron mean free path is highly affected by electronic scattering with the interfaces and defects. Here, we present a theoretical and experimental study on how thickness and microstructure affect the properties of Ag thin films. We are able to successfully model the electrical resistivity and IR optical response using a thickness dependent electronic scattering time. Remarkably, the product of electronic scattering time and resistivity remains constant regardless of the thickness (τx ρ = C), with a value of 59 ± 2 μΩ cm ⋅ fs for Ag films in the investigated range from 3 to 74 nm. Our findings enable us to develop a theoretically framework that allows calculating the optical response of metal thin films in the IR by using their measured thickness and resistivity. An excellent agreement is found between experimental measurements and predicted values. This study also shows the theoretical lower limit for emissivity in Ag thin films according to their microstructure and thickness. Application of the model presented here will allow rapid characterization of the IR optical response of metal thin films, with important application in a broad spectrum of fundamental and industrial applications, including optical coatings, low-emissivity windows and semiconductor industry.

Silver-Based Low-Emissivity Coating Technology for Energy- Saving Window Applications

“…In addition, Ref. [12] found a way to estimate the optical properties of silver (refractive index) at near IR by resistivity measurements [12].…”

“…The thin film silver thickness effects on its electrical properties were studied in many literatures, and Ref. [12] gave a good comparison of the theoretical and experimental results. Figure 16 shows experimental resistivity values (ρ) decreased as Ag films with thicknesses ranging from 3 to 74 nm and the theoretical model predictions [12].…”

Fabrication of a novel low-cost triple layer system (TaZO/Ag/TaZO) with an enhanced quality factor for transparent electrode applications

“…[5][6] Even though ITO/Ag/ITO films have been examined broadly, the rising cost of indium has forced the substitution of ITO by other metal oxides. [5][6] Even though ITO/Ag/ITO films have been examined broadly, the rising cost of indium has forced the substitution of ITO by other metal oxides.…”

Characterization of Cr/Ag Bi-Layer thin Metal Contacts Sputter Deposited on N-Type Si Semiconductor

“…Then, for the Au metal material, it has high malleability, ductility, resistance to corrosion and also one of the good electrical conductor material and has been widely used in metal contact technology [3]. As for Ag, it will produce neutral color in the range of visible light spectrum and also make it as an ideal candidates for the low thermal emissivity that is reported by Ding et al [4]. But after all, by comparing the electrical conductivity as well as their electrical resistivity, Ag offers as a good candidate to be used in metal contact technology due to its lowest electrical resistivity and highest electrical conductivity which are 1.59 × 10 -8 Ω-m and 6.30 ×10 7 (Ω-m) -1 respectively among other materials.…”