• Applied Chemistry for Engineering
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• v.20 no.6
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• pp.617-621
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• 2009

Zinc oxide (ZnO) nanorods were grown on the pre-oxidized silicon substrate with the assistance of Au and the fluorine-doped tin oxide (FTO) based on the catalysts by vapor-liquid-solid (VLS) synthesis. Two types of ZnO powder particle size, 20nm, $20{\mu}m$, were used as a source material, respectively The properties of the nanorods such as morphological characteristics, chemical composition and crystalline properties were examined by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX) and field-emission scanning electron microscope (FE-SEM). The particle size of ZnO source strongly affected the growth of ZnO nanostructures as well as the crystallographic structure. All the ZnO nanostructures are hexagonal and single crystal in nature. It is found that $1030^{\circ}C$ is a suitable optimum growth temperature and 20 nm is a optimum ZnO powder particle size. Nanorods were fabricated on the FTO deposition with large electronegativity and we found that the electric potential of nanorods rises as the ratio of current rises, there is direct relationship with the catalysts, Therefore, it was considered that Sn can be the alternative material of Au in the formation of ZnO nanostructures.

• Macromolecular Research
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• v.15 no.3
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• pp.211-215
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• 2007

Hybrid thin film nanostructures composed of metal nanoparticles (NPs) and self-assembled polymer films with different spatial distributions of NPs were analyzed by optical waveguide spectroscopy (OWS). Specifically, the dielectric constants were calculated using effective medium theory for the incorporation of 1 vol% Au NP into the block copolymer (BCP) films having a cylindrical nanodomain morphology. Three cases were considered: uniform distribution of NPs in the film; selective distribution of NPs only in the cylindrical domains; and segregation of NPs to the center of the cylindrical domains. The optical waveguide spectra derived from the calculated dielectric constants demonstrate the feasibility of experimentally distinguishing the composite nanostructures with different inner morphologies in the hybrid metal NP-BCP nanostructures, by the measurement of the dielectric constants using OWS.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.247-247
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• 2012

Plasmon subwavelength nanostructures enable the structurally modulated color due to the resonance conditions for the specific wavelength range of light with the nanoscale hole arrays on a metal layer. While the unique properties offered from a single layer of metal may open up the potential applications of integrated devices to displays and sensors, fabrication requirements in nanoscale, typically on the order of or smaller than the wavelength of light in a corresponding medium can limit the cost-effective implementation of the plasmonic nanostructures. Simpler nanoscale replication technologies based on the soft lithography or roll-to-roll nanoimprinting can introduce economically feasible manufacturing process for these devices. Such replication requires an optimal design of a master template to produce a stamp that can be applied for a roll-to-roll nanoimprinting. In this paper, a master mold with subwavelength nanostructures is fabricated and optimized using focused ion beam for the applications to nanoimprinting process. Au thin film layer is deposited by sputtering on a glass that serves as a dielectric substrate. Focused ion beam milling (FIB, JEOL JIB-4601F) is used to fabricate surface plasmon subwavelength nanostructures made of periodic hole arrays. The light spectrum of the fabricated nanostructures is characterized by using UV-Vis-NIR spectrophotometer (Agilent, Cary 5000) and the surface morphology is measured by using atomic force microscope (AFM, Park System XE-100) and scanning electron microscope (SEM, JEOL JSM-7100F). Relationship between the parameters of the hole arrays and the corresponding spectral characteristics and their potential applications are also discussed.

• Advances in nano research
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• v.9 no.2
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• pp.113-122
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• 2020

Surface-Enhanced Raman Scattering (SERS) spectroscopy is a multifaceted surface sensitive methodology which exploits spectroscopy-based analysis for various applications. This technique is based on the massive amplification of Raman signals which were feeble previously in order to use them for appropriate identification at qualitative and quantitative in chemical as well as biological systems. This novel powerful technique can be utilized to identify pathogens such as bacteria and viruses. As far as SERS is concerned, one of the most studied problems has been functionalization of SERS active substrate. Metal colloids and nanostructures or microstructures synthesized using noble metals such as Au, Ag and Cu are considered to be SERS active. Silver and gold are extensively used as SERS active substrates due to chemical inertness and stability in air compare to copper. However, use of Cu as a suitable alternative has been taken into account as it is cheap. Herein, we have synthesized air-stable copper microstructures/nanostructures by chemical, electrochemical and microwave-assisted methods. In this paper, we have also discussed the use of as synthesized copper micro/nanostructures as inexpensive yet effective SERS active substrates for the fast identification of micro-organisms like Staphylococcus aureus and Escherichia coli.

• Proceedings of the Korean Vacuum Society Conference
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• 2008.08a
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• pp.237-237
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• 2008

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.415-415
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• 2012

ZnO nanostructures were synthesized by a vapor phase transport process in a single-zone furnace within a horizontal quartz tube with an inner diameter of 38 mm and a length of 485 mm. The ZnO nanostructures were grown on Au-catalyzed Si(100) substrates by using a mixture of zinc oxide and graphite powders. The growth of ZnO nanostructures was conducted at $800^{\circ}C$ for 30 min. High-purity Ar and $O_2$ gases were pushed through the quartz tube during the process at a flow rate of 100 and 10 sccm, respectively. The sequence of ON/OFF cycles of the Ar gas flow was repeated, while the $O_2$ flow is kept constant during the growth time. The Ar gas flow was ON for 1 min/cycle and that was OFF for 2 min/cycle. The structure and optical properties of the ZnO nanostructures were investigated by field-emission scanning electron microscope, X-ray diffraction, temperature-dependent photoluminescence. The preferred orientation of the ZnO nanostructures was along c-axis with hexagonal wurtzite structure.

• Korean Journal of Materials Research
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• v.20 no.5
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• pp.262-266
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• 2010

ZnO nanostructures were grown on an Au seed layer by a hydrothermal method. The Au seed layer was deposited by ion sputter on a Si (100) substrate, and then the ZnO nanostructures were grown with different precursor concentrations ranging from 0.01 M to 0.3M at $150^{\circ}C$ and different growth temperatures ranging from $100^{\circ}C$ to $250^{\circ}C$ with 0.3 M of precursor concentration. FE-SEM (field-emission scanning electron microscopy), XRD (X-ray diffraction), and PL (photoluminescence) were carried out to investigate the structural and optical properties of the ZnO nanostructures. The different morphologies are shown with different growth conditions by FE-SEM images. The density of the ZnO nanostructures changed significantly as the growth conditions changed. The density increased as the precursor concentration increased. The ZnO nanostructures are barely grown at $100^{\circ}C$ and the ZnO nanostructure grown at $150^{\circ}C$ has the highest density. The XRD pattern shows the ZnO (100), ZnO (002), ZnO (101) peaks, which indicated the ZnO structure has a wurtzite structure. The higher intensity and lower FWHM (full width at half maximum) of the ZnO peaks were observed at a growth temperature of $150^{\circ}C$, which indicated higher crystal quality. A near band edge emission (NBE) and a deep level emission (DLE) were observed at the PL spectra and the intensity of the DLE increased as the density of the ZnO nanostructures increased.

• Mass Spectrometry Letters
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• v.15 no.1
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• pp.26-39
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• 2024

Gold nanostructures (Au NSs) are useful and interesting matrices for mass spectrometric analysis of various biomolecules based on organic matrix-free laser desorption/ionization time-of-flight mass spectrometry (LDI-TOF-MS). Au NSs provide high efficiency and versatility in LDI-TOF-MS analysis based on their well-established synthesis and surface functionalization, large surface area, high laser absorption capacity, and photothermal conversion efficiency. Therefore, Au NSs based LDI-TOF-MS can be a facile, functional, and efficient analytical method for important small biomolecules owing to its simple preparation, rapid analysis, salt-tolerance, signal reproducibility, and quantitative analysis. This review chronologically summarizes the important advance of Au NSs-based LDI-TOF-MS platforms in terms of in-depth mechanism, signal enhancement, quantitative analysis, and disease diagnosis.

• Bulletin of the Korean Chemical Society
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• v.33 no.9
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• pp.2830-2844
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• 2012

This review covers recent developments in our group regarding the synthesis, characterization and applications of single-crystalline one-dimensional nanostructures based on a wide range of material systems including noble metals, metal silicides and metal germanides. For the single-crystalline one-dimensional nanostructures growth, we have employed chemical vapor transport approach without using any catalysts, capping reagents, and templates because of its simplicity and wide applicability. Au, Pd, and Pt nanowires are epitaxially grown on various substrates, in which the nanowires grow from seed crystals by the correlations of the geometry and orientation of seed crystals with those of as-grown nanowires. We also present the synthesis of numerous metal silicide and germanide 1D nanostructures. By simply varying reaction conditions, furthermore, nanowires of metastable phase, such as $Fe_5Si_3$ and $Co_3Si$, and composition tuned cobalt silicides (CoSi, $Co_2Si$, $Co_3Si$) and iron germanides ($Fe_{1.3}Ge$ and $Fe_3Ge$) nanowires are synthesized. Such developments can be utilized as advanced platforms or building blocks for a wide range of applications such as plasmonics, sensings, nanoelectronics, and spintronics.

• Analytical Science and Technology
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• v.37 no.4
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• pp.201-210
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• 2024

Surface-enhanced Raman scattering (SERS) has emerged as a powerful technique for detecting and analyzing chemical and biological molecules at ultra-low concentrations. The effectiveness of SERS largely depends on structures with sub-10 nm gaps, prompting the proposal of various nanostructures as efficient SERS-active platforms. Among these, single-crystalline gold nanowires (AuNWs) are particularly promising due to their large dielectric constants, well-defined geometries, atomically smooth surfaces, and surface plasmon resonance across the visible spectrum, which produce strong SERS enhancements. This review comprehensively explores the synthesis, functionalization, and application of Au NWs in SERS. We discuss various methods for synthesizing AuNWs, including the vapor transport method, which influences their morphological and optical properties. We also review practical applications in chemical and biosensing, showcasing the adaptability of Au NWs-based SERS platforms in detecting a range of analytes, from environmental pollutants to biological markers. The review concludes with a discussion on future perspectives that aim to enhance sensor performance and broaden application domains, highlighting the potential of these sensors to revolutionize diagnostics and environmental monitoring. This review underscores the transformative impact of AuNW-based SERS sensors in analytical chemistry, environmental science, and biomedical diagnostics, paving the way for next-generation sensing technologies.