Influence of H2 Atmosphere Annealing on Plasmonic Properties of Cu-Containing Silica Films Sputtered on Amorphous Silica
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Copper-doped silica films have been deposited on amorphous silica (fused quartz) by magnetron co-sputtering. The resulting films were characterized for copper loading/thickness by Rutherford backscattering spectrometry, and the optical properties were evaluated by absorption and photoluminescence spectroscopies. The films were subjected to thermal treatment under a 5% H2−95% Ar-reducing atmosphere and further evaluated for surface plasmon resonance (SPR) characteristics. In addition, the occurrence of Cu nanoparticles (NPs) was evaluated by transmission electron microscopy. It is indicated that the films have effective permeability for H2, and consequently, the reduction of ionic copper takes place supporting the nucleation and growth of Cu NPs. Interestingly, along with the increase in absorption intensity of Cu NPs, the processing leads consistently to significant blue shifts in the SPR peaks. Absorption spectra were then simulated by Mie theory calculations for dielectric-embedded Cu NPs in an effort to understand the influence of particle size and medium refractive index on the SPR.
KeywordsThin films Optical materials Surface plasmon resonance
The authors thank Marushka Sendova-Vassileva for film deposition, Jean C. Pivin for RBS analyses, Miguel A. García for the program code modeling Mie resonances, Prof. Michael Lufaso from University of North Florida (UNF) for the reducing atmosphere processing, and the Major Analytical Instrumentation Center at University of Florida for TEM. J.A. Jiménez is also grateful for the participation and experimental support (e.g., collection of absorption spectra) of student Joseph Hockenbury at UNF.
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Conflict of Interest
The authors declare that they have no conflicts of interest.
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