2 research outputs found
Bimetallic nanostructures on porous silicon with controllable surface plasmon resonance
The most intensive surface plasmon resonance (SPR) band is typical for the metallic particles
of 10–150nm diameters. The SPR band of such nanoparticles is usually narrow and allows using just one
laser (i.e. limited range of excitation wavelength) to achieve the maximal enhancement of electromagnetic
field near metallic nanostructures caused by surface plasmon oscillations. It hinders usability of plasmonic
nanostructures in some application including surface enhanced Raman scattering (SERS) spectroscopy. To
overcome this hurdle enlarged metallic nanostructures are fabricated resulting in a broadening of the SPR
band due to additional oscillation modes. However, the SPR bands of the enlarged particles are characterized
by less intensity and weak enhancement at different wavelengths. In this paper, we proposed an
alternative way for the SPR band broadening by use of bimetallic nanostructures on a sculptured template.
Plasmonic substrates were fabricated by sequential copper electroplating and silver electroless deposition
on porous silicon. Presented data implies that variation in morphology and ratio of the silver/copper nanostructures
allow to control position of their SPR band from blue to near-infrared (IR) range. It is shown
that SERS-spectroscopy with the fabricated nanostructures provide equal detection limits of rhodamine
6G under red and near-IR excitation wavelengths
Fabrication and simulation of silver nanostructures on different types of porous silicon for surface enhanced Raman spectroscopy
In this paper, we propose a systematic approach to controllably fabricate silver nanoparticles, dendrites and nanovoids on
porous template based on silicon and two-step wet process. Geometry of metallic structures was managed by variation of
dopant type of silicon, regimes of template formation and deposition of silver. General models of each structure were
developed and studied for distribution and strength of electric field arising in them under 473, 633 and 785 nm laser
excitation. Simulation results revealed reasons of variable activity of the fabricated structures in surface enhanced Raman
spectroscopy, which allowed to define optimal conditions of analysis of target molecules