• Title/Summary/Keyword: Vapor synthesis

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Synthesis and Characterization of Cu(In,Ga)Se2 Nanostructures by Top-down and Bottom-up Approach

  • Lee, Ji-Yeong;Seong, Won-Kyung;Moon, Myoung-Woon;Lee, Kwang-Ryeol;Yang, Cheol-Woong
    • Proceedings of the Korean Vacuum Society Conference
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    • 2012.08a
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    • pp.440-440
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    • 2012

  • Nanomaterials have emerged as new building blocks to construct light energy harvesting assemblies. Size dependent properties provide the basis for developing new and effective systems with semiconductor nanoparticles, quantized charging effects in metal nanoparticle or their combinations in 2 and 3 dimensions for expanding the possibility of developing new strategies for photovoltaic system. As top-down approach, we developed a simple and effective method for the large scale formation of self-assembled Cu(In,Ga)$Se_2$ (CIGS) nanostructures by ion beam irradiation. The compositional changes and morphological evolution were observed as a function of the irradiation time. As the ion irradiation time increased, the nano-dots were transformed into a nano-ridge structure due to the difference in the sputtering yields and diffusion rates of each element and the competition between sputtering and diffusion processes during irradiation. As bottom-up approach, we developed the growth of CIGS nanowires using thermal-chemical vapor deposition (CVD) method. Vapor-phase synthesis is probably the most extensively explored approach to the formation of 1D nanostructures such as whiskers, nanorods, and nanowires. However, unlike binary or ternary chalcogenides, the synthesis of quaternary CIGS nanostructures is challenging because of the difficulty in controlling the stoichiometry and phase structure. We introduced a method for synthesis of the single crystalline CIGS nanowires in the form of chalcopyrite using thermal-CVD without catalyst. It was confirmed that the CIGS nanowires are epitaxially grown on a sapphire substrate, having a length ranged from 3 to 100 micrometers and a diameter from 30 to 500 nm.

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Synthesis of carbon nanosheets using RF thermal plasma (유도 열플라즈마를 이용한 카본나노시트 합성)

  • Lee, Seung-Yong;Ko, Sang-Min;Koo, Sang-Man;Hwang, Kwang-Taek;Han, Kyu-Sung;Kim, Jin-Ho
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.24 no.5
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    • pp.207-212
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    • 2014

  • An ultrathin sheet-like carbon nanostructure provides an important model of a two-dimensional graphite structure with strong anisotropy in physical properties. As an easy and cheap route for mass production, RF thermal plasma synthesis of freestanding carbon nanosheet from $CH_4$ (Methane) and $C_3H_8$ (Propane) is presented. Using vapor synthesis process with RF inductively thermal plasma, carbon nanosheets were obtained without catalysts and substrates. The synthesized carbon nanosheets were characterized using transmission electron microscopy (TEM), Raman spectroscopy, X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) analysis. The carbon nanosheets synthesized using methane and propane generally showed 5~6 and 15~16 layers with a wrinkled morphology and size of approximately 100 nm.

  • https://doi.org/10.6111/JKCGCT.2014.24.5.207 인용 PDF KSCI

Synthesis and Microstructural Changes of Nanostructured Tungsten Carbide Powder by Chemical Vapor Condensation Process (화학기상응축법에 의한 나노구조 텅스텐카바이드 분말의 제조와 미세구조 변화)

  • ;;;;O.V.Tolochko
    • Journal of Powder Materials
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    • v.9 no.3
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    • pp.174-181
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    • 2002

  • Nanosized tungsten carbide powders were synthesized by the chemical vapor condensation(CVC) process using the pyrolysis of tungsten hexacarbonyl($W(CO)_6$). The effect of CVC parameters on the formation and the microstructural change of as-prepared powders were studied by XRD, BET and TEM. The loosely agglomerated nanosized tungsten-carbide($WC_{1-x}$) particles having the smooth rounded tetragonal shape could be obtained below $1000^{\circ}C$ in argon and air atmosphere respectively. The grain size of powders was decreased from 53 nm to 28 nm with increasing reaction temperature. The increase of particle size with reaction temperature represented that the condensation of precursor vapor dominated the powder formation in CVC reactor. The powder prepared at $1000^{\circ}C$ was consisted of the pure W and cubic tungsten-carbide ($WC_{1-x}$), and their surfaces had irregular shape because the pure W was formed on the $WC_{1-x}$ powders. The $WC_{1-x}$ and W powders having the average particles size of about 5 nm were produced in vacuum.

  • https://doi.org/10.4150/KPMI.2002.9.3.174 인용 PDF KSCI