• 한국재료학회:학술대회논문집
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• 한국재료학회 2012년도 춘계학술발표대회
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• pp.86.2-86.2
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• 2012

산화금속은 높은 결정성, quantum size effect, 높은 투과도, 대기중의 안정도 등과 같은 탁월한 성질들로 인하여 오늘날 실리콘의 대체물로서 많은 연구가 보고되고 있다. 이러한 금속산화물의 크기와 모양을 조절하며 대량 생산하기 위한 합성방법으로 가수분해, 금속양이온 응축법과 같은 다양한 수용액상 방법이 연구되고 있다. 하지만 2차원 단일 층에 나노물질을 정렬하고 전기적 접합을 형성하는 것이 매우 어렵다는 점 때문에 나노물질을 기판 위에 자유롭게 성장시키는 방법에 대해서는 아직 많이 보고 되어있지 않다. 본 연구에서 저온의 수용액에서 1차원의 나노막대가 2차원의 스피넬 구조 위에 heteroepotaxial 접합을 이루며 성장시키는 방법을 이용하였다. P-n접합 형성을 위하여 (0001)방향으로 배향된 n-type ZnO 나노막대를 (111)방향의 p-type Co3O4 나노플레이트 위에 성장시킨 구조를 제작하였으며 이를 바탕으로 다이오드소자를 제작하여 ideal factor, turn-on voltage, rectifying ratio등의 전기적 특성을 평가하였다.

• 한국재료학회지
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• 제16권7호
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• pp.408-411
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• 2006

An effective wet-chemical approach is demonstrated for growing large-area, selectively-patterned, and low-temperature-synthesized ZnO nanorods (ZNRs). The growth of ZNRs was enhanced on a Co layer. The selectivity and density were readily controlled by the control of the temperature when the substrate transfers into aqueous solution. The cross-sectional transmission electron microscopy image shows that single crystalline ZNRs grown along [0001] have good adhesion at interface between ZNRs/substrate. The turn-on field was 4 $V/{\mu}m$ at the emission current density of 1 ${\mu}A/cm^2$. The stable emission was obtained at 0.11 $mA/cm^2$ under 7.2 $V/{\mu}m$ over 10 hr. These results suggest that selectively-patterned ZNRs have the potential for use as field emitters in large-area field emission displays.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.459-459
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• 2013

Si (111) 기판 위에 plasma assisted molecular beam epitaxy 법으로 Si과 Mg doping된 GaN 나노막대를 각 각 성장하고 나노막대의 모양과 광학적 특성을 조사하였다. Si이 doping된 GaN 나노막대는 biaxial m-plane 방향의 변화로 별 모양을 갖는 것을 관찰하였고 Mg doping된 GaN 나노막대의 지름은 줄어드는 것을 scanning electron microscopy로 확인하였다. 본 연구에서는 이러한 변화의 원인을 stress 때문으로 보고 x-ray diffraction과 raman scattering 측정을 통하여 구조적 변화를 조사하였다. 또한, stress에 의한 GaN 나노막대의광학적 특성 변화를 photoluminescence을 통하여 조사하였다. Doping한 GaN 나노막대의 특성조사를 통해 GaN 나노막대 성장 시 발생되는 stress의 영향을 이해하는데 중요한 정보를 제공할 것이다.

• Bulletin of the Korean Chemical Society
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• 제24권1호
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• pp.32-36
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• 2003

Co nanoparticles were prepared by the reverse micelle technique (NaBH₄reduction of cobalt chloride in a reversed micelle solution of didodecyldimethylammoniumbromide (DDAB)/toluene). The size and the shape of Co nanoparticles could be easily controlled by changing the water contents and micelle concentrations, and the solubility of Co nanoparticles was systematically tuned by choosing appropriate surface capping organic ligand molecules. Furthermore, a novel nanofabrication process was clearly demonstrated, which generated oxide over-coated Co nanorods from Co nanoparticles in organic solution by slow oxidation with an external magnetic field.

• Korean Chemical Engineering Research
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• 제53권3호
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• pp.350-356
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• 2015

The effects of the zinc oxide (ZnO) preparing process on the performance of inverted organic photovoltaic cells (OPVs) were explored. The morphology and size of ZnO nanoparticles were controlled, leading to more efficient charge collection from device and higher electron mobility compared with nanospheres. Nanosized ZnO particles were synthesized by using zinc acetate dihydrate and potassium hydroxide in methanol. Also, water was added into the reaction medium to control the morphology of ZnO nanocrystals from spherical particles to rods, and $NH_4OH$ was used to prevent the gelation of dispersion. Solution-processed ZnO thin films were deposited onto the ITO/glass substrate by using spin coating process and then ZnO films were used as an electron transport layer in inverted organic photovoltaic cells. The analyses were carried out by using TEM, FE-SEM, AFM, DLS, UV-Vis spectroscopy, current density-voltage characteristics and solar simulator.

• 한국초전도ㆍ저온공학회논문지
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• 제13권4호
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• pp.1-4
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• 2011

From the viewpoint of high field application, the mechanical and critical current properties of recently developed $REBa_2Cu_3O_y$ (RE123, RE: rare-earth) coated conductors are summarized. In addition, effective flux pinning mechanisms in RE123 are also introduced. As one of the examples for high field application, the upgrading of the 18 T cryogen-free superconducting magnet is shown. The large anisotropy of $J_c$ is a problem at low temperature and high magnetic field. The nanorod is considered as the useful methods to improve the anisotropy of $J_c$, although its efficiency becomes small at low temperature.

• 한국결정성장학회지
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• 제16권1호
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• pp.12-19
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• 2006

Metalorganic chemical vapor deposition (MOCYD) techniques have been applied to fabricate semiconducting ZnO thin films and nanostructures, which are promising for novel optoelectronic device applications using their unique multifunctional properties. The growth and characterization of ZnO thin films on Si and $SiO_2$ substrates by MOCYD as fundamental study to realize ZnO nanostructures was carried out. The precise control of initial nucleation processes was found to be a key issue for realizing high quality epitaxial layers on the substrates. In addition, fabrication and characterization of ZnO nanodots with low-dimensional characteristics have been investigated to establish nanostructure blocks for ZnO-based nanoscale device application. Systematic realization of self- and artificially-controlled ZnO nanodots on $SiO_2/Si$ substrates was proposed and successfully demonstrated utilizing MOCYD in addition with a focused ion beam technique.

• Bulletin of the Korean Chemical Society
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• 제33권12호
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• pp.3977-3980
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• 2012

Nanostructured thermoelectric bismuth telluride ($Bi_2Te_3$) powders with various morphologies, such as nanoplates, nanorods, and nanotubes, were prepared by a hydrothermal method based on the reaction between $BiCl_3$, Te, and sodium ethylenediaminetetraacetate ($Na_2$-EDTA) at 150, 180, and $210^{\circ}C$. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and selected area electron diffraction (SAED). The effect of reaction temperature on the morphology of the $Bi_2Te_3$ particles was investigated, and the possible mechanism of morphology control was proposed.

• Applied Science and Convergence Technology
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• 제23권5호
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• pp.289-295
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• 2014

${\alpha}-V_2O_5$ nanorods were grown by means of electron beam irradiation and thermal oxidation methods and the visible emission properties of the nanorods grown by both methods were investigated. The growth and crystallinity of the nanorods were greatly enhanced by the insertion of a buffer layer. The emission spectra of the nanorods grown by thermal oxidation and electron beam irradiation showed a peak centered at 710~720 nm, which is believed to be due to oxygen vacancies introduced during the growth process. Also, the emission peak centered at 530 nm observed in the $V_2O_5$ nanorods grown by electron beam irradiation was considered to be due to the band edge transition as a result of the enhanced crystallinity.

• Transactions on Electrical and Electronic Materials
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• 제4권5호
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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.