Au–Ag–Al Nano‐Alloy Thin Films as an Advanced Material for Photonic Applications: XPS Analysis, Linear and Nonlinear Optical Properties Under CW Regime

The compositional and optical properties of an aluminum‐based transition‐metal alloy system (Au–Ag–Al) as an advanced material for photonic applications are investigated. The system is fabricated by sequentially evaporating thin layers of gold, silver, and aluminum. The thickness of Al is varied to reflect different percentages in the alloyed films. Alloying of the metals is confirmed from the shifts in the electronic binding energy of the pure elements through X‐ray photoelectron spectroscopy. The current–voltage measurements demonstrate good ohmic conductivity in the films and the optical properties are obtained by standard absorption and z‐scan techniques. Plasmonic peaks are observed in the alloyed system related to the participating metals. The thermal nonlinear optical response is conducted in the continuous wave (CW) regime. The films show large values for the thermo‐optical coefficient (∂n/∂T) which results in high values (≈10−3 cm2 W−1) for the third‐order nonlinear coefficient (n2them). A discussion of these values and their impact on the application of thin alloyed metals is presented. Ultrathin films of Au–Ag–Al nano systems are fabricated using thermal evaporation. Their composite structure, linear and thermally induced nonlinear optical properties are investigated. The stability and compositional structure of these systems are verified using I–V and XPS measurements. The high nonlinear absorption coefficients of these systems may have a potential application in plasmonic heating .