Study on the substrate effect in chemical vapor deposition of graphene

Jungtae Nam,Dong-Chul Kim,Dong Yun Lee,Jun Yeon Hwang,Helge Weman,Keun Soo Kim 한국진공학회 2017 한국진공학회 학술발표회초록집 Vol.2017 No.8

Chemical vapor deposition of graphene on platinum: Growth and substrate interaction

Nam, Jungtae,Kim, Dong-Chul,Yun, Hoyeol,Shin, Dong Hoon,Nam, Seungjin,Lee, Won Ki,Hwang, Jun Yeon,Lee, Sang Wook,Weman, Helge,Kim, Keun Soo Elsevier 2017 Carbon Vol.111 No.-

<P>Low-pressure chemical vapor deposition of graphene has been investigated on various Pt substrates such as e-beam deposited films, sputtered films, and polycrystalline foils. High temperature sputtering is found to be crucial in growing single layer graphene on Pt. It gives highly (111)-oriented crystallization with a significant reduction of dewetting in Pt films, in contrast to e-beam deposited Pt films. Graphene grown on high temperature sputtered Pt films is free of micro-sized multilayer graphene islands normally observed in graphene grown on polycrystalline Pt foils. This indicates that using Pt thin films can effectively suppress the multilayer graphene growth by carbon segregations and precipitations from the Pt bulk. Growth of single layer graphene is demonstrated on Pt films with a thickness down to 25 nm. Effects of the Pt substrates on the as-grown graphene have been investigated. An XY plot of the Raman G and 2D bands in graphene shows a correlation with the surface facet orientations of the Pt substrates measured by electron backscatter diffraction. With a general red shift of the G band distributions, a blue shift of the 2D band distributions is observed, which goes as high as similar to 2750 cm(-1) in graphene grown on Pt (111) films. (C) 2016 Elsevier Ltd. All rights reserved.</P>

Efficacy and safety of thread embedding acupuncture combined with conventional acupuncture for chronic low back pain : A study protocol for a randomized, controlled, assessor-blinded, multicenter clinical trial

Leem, Jungtae,Kim, Hyunho,Jo, Hee-Geun,Jeon, Sae-rom,Hong, Yejin,Park, Yeoncheol,Seo, Byungkwan,Cho, Yeeun,Kang, Jung Won,Kim, Eun-Jung,Han, Ga Young,Kim, Jae Soo,Lee, Hyun-Jong,Kim, Tae-Hun,Nam, Dong Williams & Wilkins Co 2018 Medicine Vol.97 No.21

<P><B>Abstract</B></P><P><B>Background:</B></P><P>Back pain is one of the most common diseases, and many patients with recurrent pain seek alternative treatment strategies. Thread embedding acupuncture involves thread insertion at the acupuncture point for continuous physical and chemical stimulation. Although thread embedding is widely used in clinical practice, there is no sound evidence of its efficacy for chronic back pain. We describe the protocol for a randomized controlled trial for investigation of the efficacy and safety of thread embedding acupuncture combined with conventional acupuncture for chronic low back pain.</P><P><B>Methods:</B></P><P>This randomized, controlled, assessor-blinded, 2-armed, parallel, multicenter clinical trial will include 38 outpatients with chronic low back pain recruited from 4 traditional Korean Medicine hospitals. The patients will be randomly allocated to a treatment group (conventional acupuncture + thread embedding acupuncture) and a control group (only conventional acupuncture) in a 1:1 ratio. The treatment group patients will receive thread embedding acupuncture treatment at 10 acupuncture points (multifidus muscle, 4 points; spinal erector muscles, four points; lumbar quadrate muscle, 2 points) once a week for 8 weeks (8 sessions). In addition, all patients will receive conventional acupuncture treatment at 14 acupuncture points (GV3, EX-B5, and bilateral BL23, BL24, BL25, BL26, BL40, and BL60) twice a week for 8 weeks (16 sessions). The primary outcome will be the change in the visual analog scale score from visit 1 to visit 16, analyzed by independent <I>t</I> tests, in both groups. The groups will also be compared with regard to the clinical relevance (minimal clinically important difference), quality of life (3-level version of Euroqol-5D), disability level (Roland and Morris Disability Questionnaire), global assessment (patient global impression of change), and safety. Cost data for cost–benefit and cost-effectiveness analyses will be collected.</P><P><B>Discussion:</B></P><P>Our study results will provide evidence of the efficacy and safety of thread embedding acupuncture combined with conventional acupuncture for the management of chronic low back pain. Even though the assessors will be blinded, the patients will not be blinded to treatment because of the lack of a sham embedding acupuncture group; this is a limitation of our study.</P><P><B>Trial registration:</B></P><P>Clinical Research Information Service: KCT0002666</P>

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.

Investigations of Graphene Grown on Copper Substrates

Sangmo Cho,Yura Kang,Jungtae Nam,Keun Soo Kim,Suklyun Hong 한국진공학회 2014 한국진공학회 학술발표회초록집 Vol.2014 No.2

Visualization of CVD-grown graphene on Cu film using area-selective ALD for quality management

Hong, Kyung Pyo,Lee, Kyu Hyun,Nam, Jungtae,Kim, Kyoung Soo,Kim, Sung Hee,Kim, Boram,Kim, Kisoo,Park, Jin Sung,Lee, Jun Young,Jeong, Taehwan,Song, Young Jae,Hwang, Jun Yeon,Choi, Jae Boong,Cho, Seungmi Elsevier 2019 APPLIED SURFACE SCIENCE - Vol.496 No.-

<P><B>Abstract</B></P> <P>The present study investigates the atomic layer deposition (ALD) of an Al<SUB>2</SUB>O<SUB>3</SUB> film on graphene atop copper with water vapor (H<SUB>2</SUB>O), oxygen plasma (O<SUB>2</SUB> plasma) and ozone (O<SUB>3</SUB>) serving as oxidants. With water vapor as an oxidant, surface-sensitive deposition results in significant differences in growth on single layer graphene (SLG) and multilayer graphene (MLG). Al<SUB>2</SUB>O<SUB>3</SUB> completely covers areas of SLG, while virtually no Al<SUB>2</SUB>O<SUB>3</SUB> is deposited on areas of MLG. The MLG areas are removed by O<SUB>2</SUB> plasma, and exposed copper areas are oxidized. Information about MLG, including the location, size, and density, can be determined by employing optical microscopy. Scanning electron microscopy (SEM), Raman spectroscopy, transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) are used to confirm the validity of the surface-selective deposition of Al<SUB>2</SUB>O<SUB>3</SUB> on graphene grown on copper. We developed a process to distinguish SLG and MLG on copper. The characterization results were fed back to the synthesis conditions, and we confirmed that high-quality SLG can be grown on copper almost devoid of MLG. This characterization technique is suitable for large-area graphene (up to meter scale graphene), and can be utilized as feedback for growth and process conditions to ensure high-quality graphene.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Visualization technique is proposed through the difference of area- selective atomic layer deposition characteristics according to the oxidants. </LI> <LI> With H<SUB>2</SUB>O as an oxidant, Al<SUB>2</SUB>O<SUB>3</SUB> completely covers areas of single layer graphene, while virtually no Al<SUB>2</SUB>O<SUB>3</SUB> is deposited on areas of multilayer graphene. </LI> <LI> Multilayer graphene sites were visualized optically by oxidizing underlying copper foil. </LI> <LI> The process involved four steps (Chemical vapor deposition synthesis, area- selective atomic layer deposition, plasma treatment, thermal oxidation). </LI> <LI> This characterization technique is suitable for large-area graphene and can be utilized as feedback for conditions to ensure high-quality graphene. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Boehmite enhances hair follicle growth via stimulation of dermal papilla cells by upregulating β-catenin signaling

( Sun Hye Shin ),( Jae Wan Park ),( Esther Lee ),( Byung Chul Lee ),( Jungtae Na ),( Kwang Ho Yoo ),( Beom Joon Kim ),( Myeung Nam Kim ) 대한피부과학회 2020 대한피부과학회 학술발표대회집 Vol.72 No.1

Background: Recent developments in material technology have revealed boehmite as a new therapeutic modality for use in wound healing and scar reduction, indicating its beneficial effects. However, the biological bases of the beneficial effects of boehmite remain unknown, and the use of boehmite to promote hair growth has not yet been studied. Objectives: This study was aimed to investigate the effect of boehmite on hair growth and the underlying mechanism. Methods: Minoxidil 3%, boehmite 1%, 3%, 5% and control vehicle cream were topically applied to the shaved dorsal skin of C3H/HeJ mice 5 days per week for 7 weeks. For in vitro model, we observed dose-dependent proliferation of human dermal papilla cell (hDPC). Reverse transcriptionquantitative polymerase chain reaction (qPCR) and western blot was carried out for expression analysis of hair growth related genes. Results: The length and size of hair follicle significantly increased in boehmite-treated mice. Boehmite increased hDPC viability, alkaline phosphatase (ALP) activity, AKT/GSK3/β-catenin pathway activity, anagen-related gene expression and VEGF secretion. In addition, it accelerated hair regrowth in a catagen-anagen transition model via upregulation of β-catenin signaling and follicular cell proliferation. Conclusion: Our results indicate that bohemite accelerates hair growth, partly via its effects on critical events in the active phase of the hair follicle cycle.

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>

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.