Synthesis and optical properties of Ag/Au-TiO2 plasmonic composite thin films

In this work, composite thin films based on titanium dioxide and noble metal nanoparticles (Ag, Au and bimetallic Ag/Au alloys) (Me-TiO2) were synthesized using the RF magnetron sputtering technique. The obtained thin films were characterized by TEM, SEM, XRD analysis, and Raman spectroscopy. It was observed that annealing in an argon atmosphere led to the crystallization of the initially amorphous as-deposited TiO2 matrix. The analysis of transmission spectra revealed that the composite thin films exhibited two light absorption regions: the first is local minima in the visible range associated with localized surface plasmon resonance (LSPR) phenomena; the second is light absorption due to the energy band gap. The study demonstrates the possibility of tuning these parameters in the composite films by changing the composition of the metal NPs. The LSPR minima for Ag-TiO2 and Au-TiO2 films were located at about 485 nm and 606 nm, respectively. In the composite thin films with bimetallic similar to Ag-0.54/Au-0.46 alloy nanoparticles, the position of the absorption peak was found to be at 555 nm. The energy band gap of these films also varies almost linearly, decreasing with an increase in the Au content, so that the largest value among the annealed Me-TiO2 composites was observed for the Ag-TiO2. (c) 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

In this work, composite thin films consisting of titanium dioxide and noble metal nanoparticles (silver, gold, and bimetallic silver/gold alloys) were synthesized using RF magnetron sputtering. The resulting thin films were characterized using various techniques, including TEM, SEM, XRD analysis, and Raman spectroscopy. The study showed that annealing in an argon atmosphere induced crystallization in the initially amorphous TiO2 matrix. The composite films exhibited two light absorption regions, one associated with localized surface plasmon resonance (LSPR) phenomena and the other due to the energy band gap. The composition of the metal nanoparticles could be adjusted to tune these parameters in the composite films.