• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.9
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• pp.408-412
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• 2002

Ga$_2$O$_3$ nanobelts were synthesized from mechanically ground GaN powders with a thermal annealing in a nitrogen atmosphere. The nanobelts are with the range of about 10~200nm width and 10~50nm thickness. The nanobelt, growing along the direction perpendicular to the (010) plane and enclosed by (101) and (101) facets, shows no defect and no dislocation.

• Journal of Sensor Science and Technology
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• v.15 no.6
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• pp.406-410
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• 2006

The films of indium oxide $In_{2}O_{3}$) were deposited onto $SiO_{2}$ coated Si wafers by a thermal evaporation method. Substrate temperature was varied from $25^{\circ}C$ to $300^{\circ}C$. Deposition rate increased to $250^{\circ}C$ and then decreased rapidly. The crystallographic properties and surface morphologies of the films were investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. The films deposited at $250^{\circ}C$ were found to have a nanobelt structure. Resistor-type gas-sensors were fabricated with $In_{2}O_{3}$ films using Pt as electrodes. The resistance variation of $In_{2}O_{3}$ films with the concentration of NO gas was measured. The $In_{2}O_{3}$ films deposited at $250^{\circ}C$ showed the highest sensitivity to the NO gas.

• Proceedings of the Materials Research Society of Korea Conference
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• 2008.05a
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• pp.27.2-27.2
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• 2008

• Bulletin of the Korean Chemical Society
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• v.27 no.3
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• pp.377-380
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• 2006

The semiconductor PbS nanobelts (width 50-120 nm and length over 3 $\mu$m) were self-assembled in a simple reverse micelle solvent system containig the surfactant of polyoxyethylene (9) dodecy ether $(C_{12}E_9)$. The nanobelts synthesized were found to possess cube galena poly-crystal structure with high purity when analyzed by ED and X-ray diffraction. Significant “blue shift” from bulk material was observed on the PbS nanobelts using photoluminescence and UV-Vis spectroscopy. A mechanism involving the possible formation of nanobelts based on surfactant template was also proposed.

• Transactions on Electrical and Electronic Materials
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• v.4 no.5
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• pp.1-5
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• 2003

ZnO nanobelts, nanorods, and nanowires were synthesized at three different substrate temperatures from the thermal evaporation of ball-milled ZnO powders at 1380$^{\circ}C$. Transmission electron microscopy (TEM) revealed that the ZnO nanobelts are single crystalline with the growth direction perpendicular to the (010) lattice planes, and that the ZnO nanorods and nanowires are single crystalline with the growth directions perpendicular to the (001) and (110) lattice planes, respectively. In cathodoluminescence (CL), the peak energy of near bandedge (NBE) emission was determined for nanobelts, nanorods, and nanowires.

• Korean Journal of Materials Research
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• v.20 no.12
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• pp.686-690
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• 2010

$TiO_2$ nanowires were self-catalytically synthesized on bare Si(100) substrates using metallorganic chemical vapor deposition. The nanowire formation was critically affected by growth temperature. The $TiO_2$ nanowires were grown at a high density on Si(100) at $510^{\circ}C$, which is near the complete decomposition temperature ($527^{\circ}C$) of the Ti precursor $(Ti(O-iPr)_2(dpm)_2)$. At $470^{\circ}C$, only very thin (< $0.1{\mu}m$) $TiO_2$ film was formed because the Ti precursor was not completely decomposed. When growth temperature was increased to $550^{\circ}C$ and $670^{\circ}C$, the nanowire formation was also significantly suppressed. A vaporsolid (V-S) growth mechanism excluding a liquid phase appeared to control the nanowire formation. The $TiO_2$ nanowire growth seemed to be activated by carbon, which was supplied by decomposition of the Ti precursor. The $TiO_2$ nanowire density was increased with increased growth pressure in the range of 1.2 to 10 torr. In addition, the nanowire formation was enhanced by using Au and Pt catalysts, which seem to act as catalysts for oxidation. The nanowires consisted of well-aligned ~20-30 nm size rutile and anatase nanocrystallines. This MOCVD synthesis technique is unique and efficient to self-catalytically grow $TiO_2$ nanowires, which hold significant promise for various photocatalysis and solar cell applications.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.141-141
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• 2018

Copper is one of the most abundant metals on earth. Its oxide (CuO) is an intrinsically p-type metal-oxide semiconductor with a bandgap ($E_g$) of 1.2-2.0 eV 1. Copper oxide nanomaterials are considered as promising materials for a wide range of applications e.g., lithium ion batteries, dye-sensitized solar cells, photocatalytic hydrogen production, photodetectors, and biogas sensors 2-7. Recently, high-density and uniform CuO nanostructures have been grown on Cu foils in alkaline solutions 3. In 2011, T. Soejima et al. proposed a facile process for the oxidation synthesis of CuO nanobelt arrays using $NH_3-H_2O_2$ aqueous solution 8. In 2017, G. Kaur et al. synthesized CuO nanostructures by treating Cu foils in $NH_4OH$ at room temperature for different treatment times 9. The surface treatment of Cu in alkaline aqueous solutions is a potential method for the mass fabrication of CuO nanostructures with high uniformity and density. It is interesting to compare the gas sensing properties among CuO nanomaterials synthesized by this approach and by others. Nevertheless, none of above studies investigated the gas sensing properties of as-synthesized CuO nanomaterials. In this study, CuO nanowalls versus nanoparticles were synthesized via the oxidation process of Cu foil in NH4OH solution at $50-70^{\circ}C$. The gas sensing properties of the as-prepared CuO nanoplates were examined with $C_2H_5OH$, $CH_3COCH_3$, and $NH_3$ at $200-360^{\circ}C$.

• Journal of the Korean Vacuum Society
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• v.18 no.5
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• pp.346-351
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• 2009

Due to the decrease of line width and increase of the integration level of the device, it is expected that 'Bottom-up' method will replace currently used 'Top-down' method. Researches about 'Bottom-up' device production such as Nanowires and Nanobelts are widely held on. To utilize these technologies in devices, properties of matter should be exactly measured. Nano-indenters are used to measure the properties of nano-scale structures. Additionally, Nano-indenters provide AFM(Atomic Force Microscopy) function to get the image of the surface and get physical properties for exact position of nano-structure using this image. However, nano-indenter tips have relatively much bigger size than ordinary AFM probes, there occurs considerable error in surface image by Nano-Indenter. Accordingly, this research used 50nm Berkovich tip and 1um $90^{\circ}$ Conical tip, which are commonly used in Nano-Indenter. To find out the surface characteristics for each kind of tip, we indented the surface of thin layer by each tip and compared surface image and indentation depth. Then, we got image of 100nm-size structure by surface scanning using Nano-Indenter and compared it with surface image gained by current AFM technology. We calculated the errors between two images and compared it with theoretical error.