Optical Properties of Silver Nanoparticles Integrated Graphene Oxide Thin Films on Glass and Silicon Substrates

We report the synthesis of graphene oxide colloid, and its transformation as a few-layer graphene oxide (GO) thin film on a glass and silicon substrates using a spin coating technique for plasmonic substrates. Annealed graphene oxide (AGO) thin films of variable thicknesses are used as substrates for silver nanoparticles (Ag NPs) formation. In surface morphological study, we observed modified Ag NPs growth by the presence of AGO thin film on glass and silicon substrates when compared to substrates without AGO film. Well-separated and worm-like Ag NPs formation was observed due to the high surface diffusion of Ag provided by the underlying AGO thin film; in contrast, dense and spheroid-like NPs formation was observed on uncoated substrates. Silver NPs prepared on AGO thin films are characterized by transmittance measurements on glass substrates and total reflectance measurements on silicon substrates from 200 to 1200 nm. We observed AGO film thickness dependent quadrupolar resonances of Ag NPs and total reflectance at longer wavelengths (> 800 nm) region, while dipolar resonances are insensitive to the variation of AGO film thickness. The modified absorption/scattering profiles and intensities are explained by surface plasmon dipolar and quadrupolar resonance mode confinement variation at the AGO thin film-nanoparticles interface.