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Yanggu, South Korea

Kim S.,Korea Institute of Science and Technology | Park M.-S.,Korea Institute of Science and Technology | Geum D.-M.,Korea Institute of Science and Technology | Kim H.,Korea Institute of Science and Technology | And 5 more authors.
Current Applied Physics | Year: 2015

In this paper, we present GaAs solar cells on Si substrate by direct epitaxial growth of III-V layers on Si substrate. Fabricated solar cells have shown relatively high energy conversion efficiency of 11.17% without anti reflection coating. By analyzing external quantum efficiency, dark I-V characteristics, and photo luminescence spectra, we have found that possible defect state near the band edge strongly impact on the performance of GaAs solar cell on Si and termination of these defects will further improve the performance of GaAs solar cell directly grown on Si substrates. © 2015 Elsevier B.V. All rights reserved. Source

Park S.-J.,Korea Institute of Machinery and Materials | Lee S.-W.,Korea Institute of Machinery and Materials | Jeong S.,Korea Institute of Machinery and Materials | Lee J.-H.,Korea Institute of Machinery and Materials | And 4 more authors.
Nanoscale Research Letters | Year: 2010

For the improved surface plasmon-coupled photoluminescence emission, a more accessible fabrication method of a controlled nanosilver pattern array was developed by effectively filling the predefined hole array with nanosilver colloid in a UV-curable resin via direct nanoimprinting. When applied to a glass substrate for light emittance with an oxide spacer layer on top of the nanosilver pattern, hybrid emission enhancements were produced from both the localized surface plasmon resonance-coupled emission enhancement and the guided light extraction from the photonic crystal array. When CdSe/ZnS nanocrystal quantum dots were deposited as an active emitter, a total photoluminescence intensity improvement of 84% was observed. This was attributed to contributions from both the silver nanoparticle filling and the nanoimprinted photonic crystal array. © 2010 The Author(s). Source

Jeong N.,Korea Institute of Energy Research | Han S.O.,Korea Institute of Energy Research | Kim H.,Korea Institute of Energy Research | Hwang K.-S.,Korea Institute of Energy Research | And 3 more authors.
RSC Advances | Year: 2014

We report the synthesis of carbon-encapsulating carbonate apatite nanowires through vapor-solid growth by heat-treatment of biomass comprising calcium compounds such as CaC2O4 or CaCO3 at 900 °C using both PH3 and C2H2 as the reactants. The thermal decomposition of CaC2O4 or CaCO3 to CaO with increasing temperature (CaC2O4 → CaCO3 + CO → CaO + CO2) is the key to achieving the growth of such core-shell nanowires. First, vapor-phase reactions between the gaseous calcium species generated from the derived CaO and gaseous molecules derived from thermal reactions of the reactants (PH3 and C2H2) lead to the oriented growth of core-shell nanowires along the [001] plane. Second, the CO2 generated during the decomposition of CaCO3 may be primarily responsible for the incorporation of carbonate ions into the apatite structure. Nanowire growth with knots along the growth direction reveals that our approach is very controllable. Additional demonstrations using kenaf fibers further verify that other types of biomass too are usable. © 2014 the Partner Organisations. Source

Jeong N.,Korea Institute of Energy Research | Hong S.-K.,Korea Institute of Energy Research | Kim C.,Korea Institute of Energy Research | Kim K.,Korea Advanced Nanofab Center
Journal of the American Ceramic Society | Year: 2015

Direct integration of nanostructures into macroscopic substrates is very important for their practical applications. In this work, we report a simple method that can be introduced for the Sn-catalyzed growth of alumina nanowires on ceramic substrates such as porous disk, monolith, and foam. Our study focuses on the role of the Sn catalysts in the formation mechanisms governing nanowire growth. Using the proposed approach, hair- or grass-like tufts of 20 nm diameter nanowires grow on the surface of the ~3 μm diameter Sn particles, in a tip growth mechanism. The nanowires of α-phased polycrystalline structure grow and are packed via a complex process involving batch-by-batch, branching, and amalgamation growth. The detailed observations reveal that the Sn catalyst is key to tailoring the growth patterns of the nanowires. In addition, cathodoluminescence studies highlight the potential optical applications of the alumina nanowires. © 2015 The American Ceramic Society. Source

Cho Y.,Ewha Womans University | Kim E.,Ewha Womans University | Gwon M.,Ewha Womans University | Park H.-H.,Korea Advanced Nanofab Center | And 2 more authors.
Applied Physics Letters | Year: 2015

We compared nanopatterned Si solar cells with and without SiNx layers. The SiNx layer coating significantly improved the internal quantum efficiency of the nanopatterned cells at long wavelengths as well as short wavelengths, whereas the surface passivation helped carrier collection of flat cells mainly at short wavelengths. The surface nanostructured array enhanced the optical absorption and also concentrated incoming light near the surface in broad wavelength range. Resulting high density of the photo-excited carriers near the surface could lead to significant recombination loss and the SiNx layer played a crucial role in the improved carrier collection of the nanostructured solar cells. © 2015 AIP Publishing LLC. Source

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