Fabrication and characterization of Au dimer antennas on glass pillars with enhanced plasmonic response

Nanophotonics

article

Pedram Sadeghi¹  Kaiyu Wu²  Tomas Rindzevicius²  Anja Boisen²  Silvan Schmid¹ 

[1] Institute of Sensor and Actuator Systems;Institute for Micro- and Nanotechnology

关键词: gap plasmons;    enhanced plasmon resonance;    plasmonic sensing;    surface-enhanced Raman spectroscopy;    nonlinear response;   

DOI  :  10.1515/nanoph-2017-0011

学科分类：社会科学、人文和艺术（综合）

来源: De Gruyter

【 摘 要 】

We report on the fabrication and dark-field spectroscopy characterization of Au dimer nanoantennas placed on top of SiO 2 nanopillars. The reported process enables the fabrication of nanopillar dimers with gaps down to 15 nm and heights up to 1 μm. A clear dependence of the plasmonic resonance position on the dimer gap is observed for smaller pillar heights, showing the high uniformity and reproducibility of the process. It is shown how increasing the height of nanopillars significantly affects the recorded elastic scattering spectra from Au nanoantennas. The results are compared to finite-difference time-domain (FDTD) and finite-element method (FEM) simulations. Additionally, measured spectra are accompanied by dark-field microscopy images of the dimers, showing the pronounced change in color. Placing nanoantennas on nanopillars with a height comparable to the in-plane dimer dimensions results in an enhancement of the scattering response, which can be understood through reduced interaction of the near-fields with the substrate. When increasing the pillar height further, scattering by the pillars themselves manifests itself as a strong tail at lower wavelengths. Additionally, strong directional scattering is expected as a result of the interface between the nanoantennas and nanopillars, which is taken into account in simulations. For pillars of height close to the plasmonic resonance wavelength, the scattering spectra become more complex due to additional scattering peaks as a result of larger geometrical nonuniformities.

【 授权许可】

CC BY