Surface-enhanced Raman scattering on gold quasi-3D nanostructure and 2D nanohole arrays

Abstract

A new method was developed to fabricate unique gold quasi-3D plasmonic nanostructures on poly(dimethylsiloxane) PDMS and 2D nanohole arrays on silicon as surface-enhanced Raman scattering (SERS) substrates using electron beam lithography (EBL) with negative tone resist Ma-N 2403 and soft lithography. The size and shape of nanopillars fabricated by EBL were well controlled via different beam conditions. An enhancement factor (EF) as high as 6.4 x 10(5) was obtained for 4-mercaptopyridine molecules adsorbed on the gold quasi-3D nanostructure array on PDMS with 400 nm diameter, 100 nm spacing and 300 nm depth, while no enhancement was observed for the gold 2D nanohole array on silicon with the same diameter and spacing. The experimental results were confirmed by finite-difference time-domain (FDTD) calculations. Furthermore, the calculated total electric fields showed that the strong SERS exhibited by the gold quasi-3D nanostructure arrays on PDMS is due to the strong localized electric fields at the gold-air interface of the bottom gold nanodisc. The strong and reproducible SERS spectroscopy for molecules adsorbed on precisely controlled gold quasi-3D nanostructure arrays on PDMS makes it possible for the integration of SERS-active nanopatterns into microfluidic devices as chemical and biological sensors with molecular specificity.

Plasmonic Enhancement by a Continuous Gold Underlayer: Application to SERS Sensing

“…However, surface roughness is hard to control and it is most desirable for SERS applications to have reproducible and robust signals. Therefore, nanoscience and nanotechnology have been extensively used in recent years for SERS applications [11][12][13], especially nanofabrication [14] using techniques such as Electron Beam Lithography [11,12,[15][16][17], Focused Ion Beam [11,18], Nanoimprint Lithography (soft [11,[19][20][21] and hard [15]), Nanosphere Lithography [11,20,22]. With these nanostructured samples, SERS now cover fields like biosensing [4], electrochemical and environmental analysis [14] and new multitechniques [13] such as Femtosecond Stimulated Raman spectroscopy (FSRS) [23] or Tip-enhanced Raman spectroscopy (TERS) [24].…”

Fundamentals and applications of SERS-based bioanalytical sensing

“…Nanoholes, nanovoids, Nanodomes, nanoclusters, and nanoarrays are 3D nanostructures, which have been successfully fabricated. Nanoholes can be prepared using electron beam lithography (EBL) [67,71], focused ion beam [68], or soft lithography [66,69,121]. Nanovoid arrays are prepared using porous anodic alumina [122] or the combination of nanosphere lithography and electrochemical deposition technique [65,72,123].…”

“…Nanovoid arrays are prepared using porous anodic alumina [122] or the combination of nanosphere lithography and electrochemical deposition technique [65,72,123]. Plasmonic properties were tuned by changing the diameter and periodicity of the nanoholes to obtain maximum SERS enhancement [67,68,71]. Changing the diameter and height in nanovoids tunes their plasmonic properties [65,72].…”

“…Changing the diameter and height in nanovoids tunes their plasmonic properties [65,72]. Nanoholes and nanovoids show around 10 4 -10 6 SERS enhancement [66][67][68][69]71]. Au and Ag nanodomes were fabricated using nanoreplica molding [124,125].…”

“…Plasmonic properties can be tuned by changing physical properties such as size [48][49][50][51][52], shape and type [53][54][55][56][57][58][59][60][61], composition [62][63][64], and dimensionality (2D and 3D) [65][66][67][68][69][70][71][72][73] of the plasmonic nanostructures. When the physical characteristics of nanostructures are tuned, the resonance frequency (or wavelength) of the SPs is changed.…”