The hour-glass type nanostructures are fabricated by using the conventional Si processes. When beaming though these structures, we observed that light is collected by the micro scale pyramidal cavity, funneled through the nano-aperture by plasmonic resonance and collimated with enhanced transmission by the surrounding horn-like mirrors (optical horn-effect). Optical transmissions through pyramidal probes with various nano-aperture diameters were measured to be dependent upon the aperture area. For a diameter less than ~ 50 nm or less than area with ~10,000 nm2, the transmitted optical intensities are increasing due to the spp-mediated intra-band emission. For the aperture diameter greater than 100 nm, the strong spp-coupled emission is shown. In addition, for the Au (7×7) slit aperture array platform with the slit aperture for a ~ 10 nm width, the broad emission spectra ranging from 600 nm to 860 nm are observed possibly due to nearfield coupling with localized surface plasmon polariton (LSPP).
Recently there have been significant interests about fabrication of optical nanopore for single molecule analysis and manipulation. However, due to very small amount of the optical intensity through the tiny size of the nano-aperture, optical intensity enhancement via plasmonic effect by using pore array or periodic groove patterns have been tried. In addition, the double slits with nanoscale width is reported to provide the constructive interference of the surface plasmonic wave. In this report, the nanoscale double slits with Au aperture array has been fabricated and optically characterized.
The Au nano-hole surrounded by the periodic nano-patterns would provide the enhanced optical intensity. Hence, the nano-hole surrounded with periodic groove patterns can be utilized as single molecule nanobio optical sensor device. In this report, the nano-hole on the electron beam induced membrane surrounded by periodic groove patterns were fabricated by focused ion beam technique (FIB), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). Initially, the Au films with three different thickness of 40 nm, 60 nm, and 200 nm were deposited on the SiN film by using an electron beam sputter-deposition technique, followed by removal of the supporting SiN film. The nanopore was formed on the electron beam induced membrane under the FESEM electron beam irradiation. Nanopore formation inside the Au aperture was controlled down to a few nanometer, by electron beam irradiations. The optical intensities from the biomolecules on the surfaces including Au coated pyramid with periodic groove patterns were investigated via surface enhanced Raman spectroscopy (SERS). The fabricated nanopore surrounded by periodic patterns can be utilized as a next generation single molecule bio optical sensor.
Recently the single molecules such as protein and deoxyribonucleic acid (DNA) have been successfully characterized by using a portable solidstate nanopore (MinION) with an electrical detection technique. However, there have been several reports about the high error rates of the fabricated nanopore device, possibly due to an electrical double layer formed inside the pore channel. The current DNA sequencing technology utilized is based on the optical detection method. In order to utilize the current optical detection technique, we will present the formation of the Au nano-pore with Au particle under the various electron beam irradiations. In order to provide the diffusion of Au atoms, a 2 keV electron beam irradiation has been performed During electron beam irradiations by using field emission scanning electron microscopy (FESEM), Au and C atoms would diffuse together and form the binary mixture membrane. Initially, the Au atoms diffused in the membrane are smaller than 1 nm, below the detection limit of the transmission electron microscopy (TEM), so that we are unable to observe the Au atoms in the formed membrane. However, after several months later, the Au atoms became larger and larger with expense of the smaller particles: Ostwald ripening. Furthermore, we also observe the Au crystalline lattice structure on the binary Au-C membrane. The formed Au crystalline lattice structures were constantly changing during electron beam imaging process due to Spinodal decomposition; the unstable thermodynamic system of Au-C binary membrane. The fabricated Au nanopore with an Au nanoparticle can be utilized as a single molecule nanobio sensor.
We investigated single wall carbon nanotubes (SWCNTs) synthesized by the HiPCO method and further processed with nitronium hexafluoroantimonate (NO2SbF6 : NHFA) treatment using continuous resonant Raman scattering in the range of 570-900 nm. According to the population ratio calculation results from Raman scattering data, it is obvious that semiconducting SWCNTs with small diameter and metallic SWCNTs were selectively removed by NHFA.
We have demonstrated the directional control of surface plasmon polariton(SPP) waves through propagating in an
asymmetric plasmonic Bragg resonator using femtosecond temporal-phase control via the resonant coupling of SPPs and
the interference of SPPs. The near-field images display significant temporal-phase dependence, switching between left
and right propagation after the Bragg resonator.