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RISS 인기검색어
- 검색키워드
- 저자 : Lee Imbok (검색결과 5 건)
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Rapid synthesis of graphene by chemical vapor deposition using liquefied petroleum gas as precursor
Lee, Imbok,Bae, Dong Jae,Lee, Won Ki,Yang, Cheol-Min,Cho, Sung Won,Nam, Jungtae,Lee, Dong Yun,Jang, A-Rang,Shin, Hyeon Suk,Hwang, Jun Yeon,Hong, Suklyun,Kim, Keun Soo Elsevier 2019 Carbon Vol.145 No.-
<P><B>Abstract</B></P> <P>In this study, the rapid synthesis of graphene via chemical vapor deposition (CVD) using liquefied petroleum gas (LPG), a common and low-cost carbon source majorly composed of butane and propane, as the precursor is investigated. For the synthesis of high-quality graphene, the growth conditions are optimized by controlling CVD parameters such as growth time, temperature, gas amount, and flow rate. Thus, graphene is successfully obtained from LPG in a short time. This synthesis is 10 times faster than that the conventional synthesis using methane as the carbon source. In the X-ray photoelectron spectra, the rapidly grown graphene samples obtained from LPG show small S2p signals due to the presence of few tens ppm ethanethiol in commercial LPG. In addition, graphene is synthesized using a hydrogen and LPG mixture to investigate the quality of graphene. Both samples are characterized by their peak positions and full width at half maximum values of the G and 2D peaks in the Raman spectra and Dirac points in the electrical measurements. In particular, the Dirac points of the graphene sample obtained with a growth time of 1 min sample appear around −22 V<SUB>G</SUB> and the sample's mobility is about 1600 cm<SUP>2</SUP>/V⋅s.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
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Rapid chemical vapor deposition of graphene using methanol as a precursor
Imbok Lee,Jungtae Nam,Sang Jun Park,Dong Jae Bae,Suklyun Hong,Keun Soo Kim 한국탄소학회 2021 Carbon Letters Vol.31 No.2
In this study, graphene was rapidly grown by chemical vapor deposition using a liquid cell for supplying methanol as a carbon source of graphene. To realize the rapid growth, methanol which is carbon-contained organic solvent was used instead of methane gas, a widely used carbon source for graphene growth. The graphene grown with the growth time as a variable was transferred to a SiO2/ Si substrate with an oxide thickness of 300 nm to confirm whether it was grown with full coverage with an optical microscope. The results confirmed a full coverage in 0.5 min of growth. The Raman spectra also confirmed the G-peak position at 1585.0 cm?1 and an intensity ratio of 2D/G at 2.3 or higher. Concerning electrical transport characteristics, at an induced carrier density of 1 × 1012 cm?2, the hole (μh) and electron (μe) mobilities were 1524 cm2 V?1 s?1 and 1528 cm2 V?1 s?1, respectively. Thus, our study confirmed that high-quality, large-area graphene can be grown within 0.5 min.
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남정태,Lee Imbok,Lee Dong Yun,Kim Minjae,Kim Keun Soo 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.76 No.10
In this study, we optimized the condition for forming a single-crystal (111) Cu substrate by using polycrystalline Cu and an abnormal grain growth method. As a result, a single-crystal (111) Cu surface could be formed through annealing for 2 hours in an H2 (100 sccm) and Ar (200 sccm) gas atmosphere (pressure 70 Torr) at 1050 °C. The crystallinity of the Cu-surface was confirmed by using X-ray diffraction analysis and electron backscatter diffraction (EBSD) pattern imaging and mapping. In addition, chemical vapor deposited graphene was synthesized before and after the crystallinity control of the substrate, and then transferred onto an SiO2 (300 nm)/Si substrate to perform a Raman spectral analysis and to evaluate the electrical properties through graphene field effect transistor device fabrication. In particular, the mobility of graphene grown on polycrystalline Cu is μh = 1228 (μe = 1158) cm2·V-1·s-1 while the carrier mobility of graphene synthesized on a single-crystal Cu surface is μh = 3353 (μe = 3200) cm2·V-1·s-1, showing an improvement of about 273% (276%). Such a single-crystal substrate can be widely used for the synthesis of high-quality 2-dimensional materials and can be reused after the material has been transferred by using a metal etching-free transfer method.
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Growth of free-standing SnO nanostructures on single layer graphene
Kim, Mee-Ree,Lee, Imbok,Kim, Keun Soo,Kim, Ki-Chul Elsevier 2019 Materials letters Vol.236 No.-
<P><B>Abstract</B></P> <P>The physical properties of nano-sized metal oxide semiconductors are influenced by the nanostructures as well as the crystallinity, thus the growth of crystalline tin oxide (SnO) with controlled morphologies would be important to its applications. To date, the various morphologies of SnO have been successfully synthesized such as nanodisks, nanobelts, nanoplatelets, nanoslabs, nanoflowers, and nanobranches. Here, the vertical free-standing SnO nanostructures were densely grown on single layer graphene (SLG) by vapor transport method. Compared with the tilted SnO nanostructures on SiO<SUB>2</SUB>/Si substrate, surface area ratio of the free-standing SnO nanostructures exhibit over of 4.4 times. According to analysis results such as Raman spectroscopy, FE-SEM, XRD, and FE-TEM, uniform and high quality free-standing SnO nanostructures were grown on large area SLG. We observed that the synthetic shapes of SnO nanostructures are different depending on the presence or absence of graphene film on substrate.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Free-standing nanostructures of SnO were densely grown on single layer graphene. </LI> <LI> Uniform & large area free-standing nanostructures of SnO were grown on SLG. </LI> <LI> Tilted nanostructures of SnO were grown on Si substrate, grown in same batch. </LI> <LI> Free-standing SnO/graphene would be applied promising anode material of Li-ion battery. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
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화학기상증착법을 이용한 그래핀의 물성 조절: 그래핀과 질소-도핑된 그래핀
박상준,이임복,배동재,남정태,박병준,한영희,김근수,Park, Sang Jun,Lee, Imbok,Bae, Dong Jae,Nam, Jungtae,Park, Byung Jun,Han, Young Hee,Kim, Keun Soo 한국전력공사 2015 KEPCO Journal on electric power and energy Vol.1 No.1
본 연구에서는 그래핀의 인위적인 합성방법인 화학기상증착법을 활용하여 합성 파라미터들을 변화시켜줌으로써 그래핀의 물성을 조절하는 연구를 수행하였다. 먼저, 메탄가스를 탄소원으로 순수 그래핀을 합성하였고, 액상의 피리딘을 원료로 사용하여 질소가 도핑된 그래핀을 합성하였다. 각각의 그래핀의 물성은 라만 분광법, X선 광전자 분광법(XPS)을 통한 기초 광물성 측정과 게이트 전압에 따른 그래핀 채널의 전류-전압 응답특성을 통한 전기적 수송현상 측정에 의해 평가되었다. 메탄가스로 합성된 그래핀의 라만 분광 스펙트럼에서는 G-peak과 2D-peak가 선명히 보였고, XPS에서 C1s-peak가 선명하였고, 아울러 전하중성점은 게이트 전압 약 +4 V 정도에서 나타났다. 피리딘을 원료로 합성된 그래핀의 라만 분광 스펙트럼에서는 D-peak, G-peak 그리고 다소 약해진 2D-peak 등이 보였고, XPS에서는 C1s-peak은 물론 N1s-peak도 나타났으며, 전하중성점은 게이트 전압 약 -96 V 정도에서 나타났다. 결과적으로 우리는 화학기상증착법을 활용하여 그래핀의 물성을 성공적으로 조절하였다. In this research, pristine graphene was synthesized using methane ($CH_4$) gas, and N-doped graphene was synthesized using pyridine ($C_5H_5N$) liquid source by chemical vapor deposition (CVD) method. Basic optical properties of both pristine and N-doped graphene were investigated by Raman spectroscopy and XPS (X-ray photoemission spectroscopy), and electrical transport characteristics were estimated by current-voltage response of graphene channel as a function of gate voltages. Results for CVD grown pristine graphene from methane gas show that G-peak, 2D-peak and C1s-peak in Raman spectra and XPS. Charge neutral point (CNP; Dirac-point) appeared at about +4 V gate bias in electrical characterization. In the case of pyridine based CVD grown N-doped graphene, D-peak, G-peak, weak 2D-peak were observed in Raman spectra and C1s-peak and slight N1s-peak in XPS. CNP appeared at -96 V gate bias in electrical characterization. These result show successful control of the property of graphene artificially synthesized by CVD method.
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