Modulation of the gold particle-plasmon resonance by the metal-semiconductor transition of vanadium dioxide

We report experimental observations of relative blue-shifts in the particle-plasmon resonance of gold nanoparticles (Au NPs) covered with a vanadium dioxide (VO2) film as the VO2 material undergoes a semiconductor-to-metal transition at approximately 67 degrees C. Although the extinction spectra of the Au NPs exhibit significant red-shifts in the presence of the surrounding VO2 film as compared to the same particles in air, the key result of this work is the dynamically controlled blue-shift of the Au-NP dipole resonance upon thermal switching of the VO2 overlayer from the semiconducting to the metallic state. We also report on the size and polarization dependence of the extinction spectra for both states, and present Mie theory calculations that confirm in a semi-quantitative way the observed trends in the VO2-induced modulation of the Au-NP plasmon resonance, and their origin in the VO2 dielectric function.