Optical Properties of Al@Al2O3 Nanorod as a UV and Visible Wavelengths Plasmonic Nanostructure

摘要

Aluminum as a new plasmonic material shows deep ultraviolet plasmon resonances which are broadly tunable. The use of aluminum plasmonic nanostructures offers new approaches, such as access high energy regions of the spectrum, low-cost and sustainable material. Therefore, aluminum is capable of being alternative plasmonic material compared to conventional gold and silver nanostructures. In this research, surface plasmon resonance properties of Al@Al2O3 core@shell nanorods in different dielectric environments were investigated. Using boundary element method and MNPBEM simulation package the sensitivity of aluminum plasmon resonance to the presence of Al2O3 layer, different aspect ratios and different dielectric mediums were studied. Results show that in Al nanorods with diameter of 3 nm increasing length from 3 to 7 nm plasmon longitudinal peak wavelength monotonously increase from 138 nm to 213 nm. In Al@Al2O3 nanorods with the same size and presence of 0.5 nm Al2O3 oxide layer the peak wavelengths dramatically shift to higher values from 307 nm to 514 nm in the middle of visible region. Plasmon resonance sensitivity to medium refractive index was also investigated. Both aluminum and Al@Al2O3 nanorods exhibit red shift of longitudinal plasmon resonance wavelength by increasing refractive index from 1 to 2. Furthermore, red shift of plasmon peak wavelength by refractive index is linear in both cases. Finally results show that plasmonic response of Al@Al2O3 nanorods depend sensitively on presence of oxide layer, size and dielectric medium. As a new plasmonic material, Al@Al2O3 nanorods are capable for tremendous application due to wide ranges of plasmon resonances from deep UV to the middle of visible region.