• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.2
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• pp.189-194
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• 2006

Ordered nanostructure materials have received attention due to their unique physical properties and potential applications in electronics, mechanics and optical devices. To actualize most of the proposed applications, it is quite important to obtain highly ordered nanostructure arrays. The well-aligned nanostructure can be achieved by synthesizing nanostructure material in the highly ordered template. To get well-aligned pore array and reduce process time, rapid thermal anneal by an IR lamp was employed in vacuum state at $500^{\circ}C$ for 2 hour. The pore array is comparable to a template annealed in vacuum furnace at $500^{\circ}C$ for 30 hours. The well-fabricated AAO template has the mean pore diameter of 70 nm, the barrier layer thickness of 25 nm, the pore depth of $9{\mu}m$, and the pore density of higher than $1.2{\times}10^{10}cm^{-2}$.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.1
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• pp.97-101
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• 2016

ZnO has nanostructured material because of unique properties suitable for various applications. Amongst all chemical and physics methods of synthesis of ZnO nanostructure, the hydrothermal method is attractive for its simplicity and environment friendly condition. Nanostructure ZnO thin films have been successfully synthesized on fluorine doped tin oxide (FTO) substrate using hydrothermal method. A possible growth mechanism of the various nanostructures ZnO is discussed in schematics. The prepared materials were characterized by standard analytical techniques, i.e., X-ray diffraction (XRD) and Field-emission scanning electron microscopy (SEM). The XRD study showed that the obtained ZnO nanostructure thin films are in crystalline nature with hexagonal wurtzite phase. The SEM image shows substrate surface covered with nanostructure ZnO nanrod. The UV-vis absorption spectrum of the synthesized nanostructure ZnO shows a strong excitonic absorption band at 365 nm which indicate formation nanostructure ZnO thin film. Photoluminescence spectra illustrated two emission peaks, with the first one at 424 nm due to the band edge emission of ZnO and the second broad peak centered around 500 nm possibly due to oxygen vacancies in nanostructure ZnO. The Raman measurements peaks observed at $325cm^{-1}$, $418cm^{-1}$, $518cm^{-1}$ and $584cm^{-1}$ indicated that nanostrusture ZnO thin film is high crystalline quality. We trust that nanostructure ZnO material can be effectively will be used as a highly active and stable phtocatalysis application.

• Ceramist
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• v.21 no.3
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• pp.283-292
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• 2018

Here, we introduce various type of inorganic nanostructure synthesized with functional nanoparticles and silica. From two decades ago, functional inorganic nanoparticles have been synthesized and highlighted, now we moved to next level of wet-chemical synthesis. By integrating functional nanoparticles with silica, we were able to synthesize multi-functional nanostructure, which expand the applications of nanoparticles to catalyst, drug carrier, sensors. In this context, silica has been spotlighted due to its versatility. Silica has highly biocompatible, relatively transparent and stable under harsh conditions. Thus it can be used as good supporter to synthesize complex multi-functional nanostructure when mixed with other functional nanoparticles. A various shape of complex nanostructures have been synthesized including core-shell type, yolk-shell type and janus type etc. In this paper, we have described the purposes of synthesizing silica noncomplex and various case studies for biomedical applications and self-assembly.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.408-408
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• 2014

Graphene has received attention with its high electron mobility and visual transparency as a promising material for optoelectronic and photonic applications. Combination of graphene and conducting nanostructures i.e. plasmonic structures has recently been researched for enhancing light-matter interaction and overcoming diffraction limit of light. Here we show enhanced photodetection of incoherent visible light with graphene-mediated plasmonics. Gold nanoparticles fabricated by focused ion beam was used as an active element of photodetection and graphene was utilized as an interfacing material between nanostructures and electrodes. Hot electrons generated upon plasmon decay within nanoparticles pass over the potential barrier between nanostructure and graphene and give rise to a photocurrent with built-in electric field. We report 76.7% enhancement of photocurrent under resonant irradiation of fiber-coupled halogen lamp compared to the case without light illumination. We showed wavelength-dependent current response arisen from plasmonic nanostructure, providing a good agreement with theoretical calculation.

• Journal of the Korean Electrochemical Society
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• v.16 no.2
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• pp.81-84
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• 2013

We demonstrate rutile $TiO_2$ branched nanostructure ($TiO_2$-BN) electrodes synthesized by seeding method for enhanced lithium intercalation properties. The morphology and crystalline nature of the $TiO_2$-BN were clearly observed by field-emission transmission electron microscopy and fast Fourier transform pattern. The $TiO_2$-BN electrodes showed excellent capacity and high rate performance. The improved lithium-ion intercalation properties of the $TiO_2$- BN may be attributed to relatively large specific surface area and short transport distance of the branched nanostructure.

• Transactions on Electrical and Electronic Materials
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• v.7 no.2
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• pp.58-61
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• 2006

Carefully designed ZnO nanowire-film hybrid nanostructure, composed of a bottom ZnO film, ZnO nanowire arrays, and a top ZnO film, was consecutively fabricated by adjusting the supersaturation conditions using a metal-organic chemical vapor deposition (MOCVD) to utilize the vertically aligned ZnO nanowires as the oxygen sensors. The decrease of current flow through ZnO nanowire arrays increasing oxygen pressure showed the high potential for the application of the ZnO hybrid nanostructure to the oxygen sensors. In addition, it was confirmed that the oxygen sensing characteristics of this hybrid nanostructure were attributed to the defects near the surface of the nanowires.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.116-117
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• 2006

I-D ZnO nanostructures were fabricated by thermal evaporation method on Si(100), GaN and $Al_2O_3$ substrates without a catalyst at the reaction temperature of $700^{\circ}C$. Only pure Zn powder was used as a source material and Ar was used as a carrier gas. The shape and growth direction of synthesized ZnO nanostructures is determined by the crystal structure and the lattice mismatch between ZnO and substrates. The ZnO nanostructure on Si substrate were inclined regardless of their substrate orientation. The origin of ZnO/Si interface is highly lattice-mismatched and the surface of the Si substrate inevitably has the $SiO_2$ layer. The ZnO nanostructure on the $Al_2O_3$ substrate was synthesized into the rod shape and grown into particular direction. For the GaN substrate, however, ZnO nanostructure with the honeycomb-like shape was vertically grown, owing to the similar lattice parameter with GaN substrate.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.33 no.4
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• pp.239-243
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• 2007

When Perfluorinated Compounds (PFCs) are applied in cosmetic products, they have many merits because of unique feeling and characters. However, it is very difficult to use them as cosmetic ingredients because they are insoluble material in oil and water and have high specific gravity. To develop a special system to stabilize PFCs in cosmetic products, we compared three systems, of gel network system, spherulite lamellar system, and nanostructure system. We found that nanostructure system was the optical system for stabilizing PFCs.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.2
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• pp.156-161
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• 2011

The present study introduces a novel wet etching technique for nanostructure fabrications which usually requires low surface roughness. Using the current method, acquired profiles were smooth even in the nanoscale, which cannot be easily achieved with conventional wet or dry etching methods. As one of the most popular single crystal silicon etchant, potassium hydroxide (KOH) solution was used as a base solvent and two additives, antimony trioxide (Sb2O3) and ethyl alcohol were employed in. Four experimental parameters, concentrations of KOH, Sb2O3, and ethyl alcohol and temperature were optimized at 60 wt.%, 0.003 wt.%, 10 v/v%, and $23^{\circ}C$, respectively. Effects of additives in KOH solution were investigated on the profiles in both (110) and (111) planes of single crystal silicon wafer. The preliminary results show that additives play a critical role to decrease etch rate significantly down to ~2 nm/min resulting in smooth side wall profiles on (111) plane and enhanced surface roughness.

• Textile Coloration and Finishing
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• v.26 no.4
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• pp.347-352
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• 2014

Film thickness dependent nanostructure evolution by a post annealing was investigated in poly (3-hexylthiophene):phenyl-C61-butyric acid methyl ester(P3HT:PCBM) films for organic solar cells which were fabricated by dichlorobenzene(DCB) solvent. In case of a 70nm thin film, the thermal annealing process affected to slight increment of the P3HT crystals in the surface region. On the other hand, large number of small sized P3HT crystals near the surface region was formed in the 200nm thick film. The solar cell devices showed the 3% power conversion efficiency(PCE) in 1:0.65 and 1:1 ratio(by weight) of P3HT and PCBM in 70nm and 200nm thickness conditions, respectively. Despite to the similar PCE, the short circuit current Jsc was different in 70nm and 200nm devices, which was related to the different nanostructure of P3HT:PCBM after thermal annealing.