The Effects of Surface Oxidation and Interparticle Coupling on Surface Plasmon Resonance Properties of Aluminum Nanoparticles as a UV Plasmonic Material

Aluminum as a new plasmonic material is of great significance and can be used in array-based chemical and biological sensors instead of silver and gold with lower cost and more amenable manufacturing. It is vital to prevent oxidation and material degradation, in order to improve the performance and sensitivity of aluminum based surface plasmon resonance (SPR) devices. Aluminum nanoparticles passivate by forming the surrounding oxide layer. In this research, SPR properties of aluminum nanoparticles in different dielectric environments were investigated. Using boundary element method and MNPBEM simulation package the sensitivity of aluminum plasmon resonance to the presence of surrounding oxide layer, two nanoparticle coupling and different dielectric mediums were studied. Results show that in core-shell nanoparticles SPR peak position shifts from 170 nm to 206 nm by increasing shell thickness from 1 to 5 nm. In coupled Al nanoparticles by decreasing the gap distance between the particles from 20 to 0 nm the SPR longitudinal peak wavelength redshifted from 137 nm to 167 nm. Finally we study the effect of different embedding medium refractive indexes. Increasing dielectric matrix refractive index from 1 to 2 leads to redshift in SPR peak wavelength from 154 nm to 202 nm. Furthermore, enhancement of SPR peak position by refractive index is linear. In conclusion, the results show that aluminum can be used as a suitable substitution of conventional plasmonic materials especially for UV-plasmonic applications.