• Title/Summary/Keyword: CVD growth

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A scientific understanding of Mammary gland and physiology of lactation in Ayurveda.

  • Verma, Vandana;Agrawal, Sonam;Gehlot, Sangeeta
    • CELLMED
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    • v.10 no.1
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    • pp.4.1-4.4
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    • 2020
  • Ayurveda scholars have well described about the physio-anatomical aspect of mammary gland (Stana), physiology of lactation, importance of breast milk (Stanya) in growth and development of baby, various factors affecting the lactation and causing changes in property of milk, Galactogouge (Stanyajanana), and drugs for purification of mother milk (Stanya Shodhana). The recent studies provide evidence for above descriptions of Ayurveda. Breast milk (Stanya) is the nearly complete sole source of nourishment for infants. It has been considered as subsidiary tissue (Upadhatu) of blood plasma (Rasa Dhatu) as it is formed out of Rasa Dhatu (Plasma) and its quality and quantity gets affected by quality of nutrient fraction of food formed after complete digestion (Aahar Rasa). It provides health (Aarogya), strength and immunity (Bala) to the feeding child and gives innumerable beneficial effects like protection against not only acute infections like URTI, diarrhoea but also on chronic illnesses like CVD, metabolic disorders too. The Ayurveda description related to Mammary gland and physiology of lactation still need a better understanding for its implementation on promotion of health. Thus an attempt has been made to compile and analyze the view of Ayurveda scholars on Breast (Stana), Breast milk (Stanya) and physiological aspect of lactation as well as to draw a possible scientific understanding for the relevance.

Electrical Properties of Local Bottom-Gated MoS2 Thin-Film Transistor

  • Kwon, Junyeon;Lee, Youngbok;Song, Wongeun;Kim, Sunkook
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.375-375
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    • 2014
  • Layered semiconductor materials can be a promising candidate for large-area thin film transistors (TFTs) due to their relatively high mobility, low-power switching, mechanically flexibility, optically transparency, and amenability to a low-cost, large-area growth technique like thermal chemical vapor deposition (CVD). Unlike 2D graphene, series of transition metal dichalcogenides (TMDCs), $MX_2$ (M=Ta, Mo, W, X=S, Se, Te), have a finite bandgap (1~2 eV), which makes them highly attractive for electronics switching devices. Recently, 2D $MoS_2$ materials can be expected as next generation high-mobility thin-film transistors for OLED and LCD backplane. In this paper, we investigate in detail the electrical characteristics of 2D layered $MoS_2$ local bottom-gated transistor with the same device structure of the conventional thin film transistor, and expect the feasibility of display application.

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Growth of vertically aligned carbon nanotubes on a large area silicon substrates by chemical vapor deposition (CVD 에 의한 대면적 실리콘기판위에서 수직방향으로 정렬된 탄소나노튜브의 성장)

  • Lee, Cheol-Jin;Park, Jeong-Hoon;Son, Kwon-Hee;Kim, Dae-Woon;Lee, Tae-Jae;Lyu, Seung-Chul
    • Proceedings of the KIEE Conference
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    • 1999.11d
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    • pp.860-862
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    • 1999
  • we have grown vertically aligned carbon nanotubes on a large area of Co-Ni codeposited Si substrates by thermal chemical vapor deposition using $C_{2}H_{2}$ gas. The carbon nanotubes grown by the thermal chemical vapor deposition are multi-wall structure, and the wall solace of nanotubes is covered with defective carbons or carbonaceous particles. The carbon nanotubes range from 50 to 120nm in diameter and about $130{\mu}m$ in length at $950^{\circ}C$. The turn-on voltage was about $0.8V/{\mu}m$ with a current density of $0.1{\mu}A/cm^2$ and emission current reveals the Fowler-Nordheim mode.

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Field emission properties of carbon nanotubes grown on micro-tip substrates using an electrophoretic deposition method (미세 팁 기판 위에 전기영동법으로 성장시킨 탄소 나노튜브의 전계방출 특성)

  • Chang, Han-Beet;Noh, Young-Rok;Kim, Jong-Pil;Park, Jin-Seok
    • Journal of the Semiconductor & Display Technology
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    • v.9 no.4
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    • pp.7-12
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    • 2010
  • Field-emission characteristics of carbon nanotubes(CNTs), which were grown on conical-type tungsten micro-tips by using an electrophoretic deposition(EPD) method, were examined. The EPD method proved to be convenient to manipulate and arrange CNTs from well dispersed suspensions onto such tip-type substrates. The growth rate of CNTs was proportional to the applied d.c. bias voltage and the process time. It was observed from the Raman study that the EPDproduced CNTs showed better crystal qualities with the Raman intensity ratio( $I_D$/$I_G$) of 0.41-0.42 than the CVD-produced CNTs and their crystal qualities could be further improved by thermal annealing. The electron emitters based on the EPDCNTs showed excellent field emission properties, such as the threshold voltage for electron emission of about 620 V and the maximum emission current of about 345 ${\mu}A$. In addition, the EPD-CNTs exhibited the stable long-term(up to 40 h) emission capability and the emission stability was enhanced by thermal annealing.

Effects of SiO$_2$ Buffer Layer on Properties of ZnO thin films and Characteristics of SAW Devices with a Multilayered Configuration of IDT/ZnO/SiO$_2$/Si (SiO$_2$ 완충층이 ZnO 박막의 물성 및 IDT/ZnO/SiO$_2$/Si 다층막 구조 표면탄성파 소자의 특성에 미치는 영향)

  • Lee, Jin-Bok;Lee, Myeong-Ho;Park, Jin-Seok
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.51 no.9
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    • pp.417-422
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    • 2002
  • ZnO thin films were deposited on various substrates, such as Si-(111), SiO$_2$(5000 $\AA$ by thermal CVD)/Si-(100), and SiO$_2$(2000 $\AA$ by RF sputtering)/Si-(100). The (002)-orientation, surface morphology and roughness, and electrical resistivity of deposited films were measured and compared in terms of substrate. Surface acoustic wave(SAW) filters with a multilayered configuration of IDT/ZnO/SiO$_2$/Si were also fabricated and the IDT was obtained using a lift-off method. From the frequency-response characteristics of fabricated devices, the insertion loss and side-lobe rejection were estimated. The experimental results showed that the (002)-oriented growth nature of ZnO films, which played a crucial role of determining the characteristic of SAW device, was strong1y dependent upon the SiO$_2$buffer.

The influence of post-treatment using hydrogen ion bombardment on microstructures and field-emission properties of carbon nanotubes (수소 이온 충돌을 이용한 후처리가 탄소 나노튜브의 구조적 물성 및 전계방출 특성에 미치는 영향)

  • Yun, Sung-Jun;Park, Chang-Kyun;Park, Jin-Seok
    • Proceedings of the KIEE Conference
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    • 2006.07c
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    • pp.1444-1445
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    • 2006
  • Carbon nanotubes (CNTs) are grown on TiN-Coated silicon substrates at $700^{\circ}C$ using an ICP-CVD method. Ni catalysts for CNT growth are formed using an RF magnetron sputtering system. Post-treatment using hydrogen ions has been performed in the ICP reactor by varying the treatment period. The characterization using various techniques, such as FESEM, HRTEM, and Raman spectroscopy, show that the physical dimension as well as the crystal quality of CNTs are changed by the post-treatment process. It is also seen that the hydrogen ion-bombardment may change the surface structure of CNTs, which may lead to produce better electron emission properties. The physical reason for all the measured data obtained are discussed to establish the relationship between the structural property and the electron emission characteristic of CNTs.

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Growth of Carbon Nanotubes at Low temperature by HF-PECVD (Hot-filament 화학기상증착법을 이용한 탄소나노튜브의 저온 성장)

  • Chang, Yoon-Jung;Choi, Eun-Chang;Park, Yong-Seob;Choi, Won-Seok;Hong, Byung-You
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2007.11a
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    • pp.151-152
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    • 2007
  • 탄소나노튜브(CNTs)는 우수한 물리적, 화학적, 기계적 특성으로 다양한 분야에서 연구가 진행 되고있다. 특히, field emission displays (FEDs)로의 응용을 위해서는 기본적으로 sodalime glass 위에 직접 CNTs를 성장시켜야 하며, 소자 응용을 위해 기판인 sodalime glass를 왜곡시키는 온도보다 낮은 온도에서 CNT의 수직 성장이 이루어져야 한다. 본 연구에서는 Hot-filament plasma enhanced chemical vapor deposition (HF-PECVD)를 이용하여 합성온도를 400, 450, 500, $550^{\circ}C$로 변화시켰으며 촉매 층인 Ni의 두께를 5~40 nm까지 조절하여 탄소나노튜브를 합성하였다. 저온에서 합성된 탄소나노튜브는 FE-SEM을 이용하여 성장 형태 및 표면 특성을 확인하였으며, 미세구조는 HR-TEM을 이용하여 확인하였다.

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Effect of Hydrogen Plasma Pre-treatment on Growth of Carbon Nanotubes by a Microwave PECVD Method (마이크로웨이브 플라즈마 화학기상증착장비를 사용하여 합성한 탄소나노튜브의 니켈 촉매층 수소 플라즈마 전처리조건에 따른 성장특성)

  • Choi, Won-Seok;Choi, Sung-Hun;Hong, Byung-You;Kim, Jung-Tae;Lim, Dong-Gun;Yang, Kea-Joon;Park, Young;Kim, Do-Young;Lee, Jae-Hyeoung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.07a
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    • pp.189-190
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    • 2005
  • 본 논문에서는 탄소나노튜브를 성장시키기 전 과정인 전처리시 촉매 층에 인가되는 마이크로웨이브 파워에 따른 탄소나노튜브의 성장 및 특성 변화를 관찰하였다. 촉매층으로 사용되는 Ni층과 adhesion층으로 사용되는 Ti층은 마그네트론 스퍼터링 방식으로 증착하였고, 탄소나노튜브 성장에는 마이크로웨이브 플라즈마 화학기상 증착기를 사용하였다 탄소나노튜브의 성장특성은 평면과 단면 SEM image를 통하여 관찰하였으며, Raman spectrometer 분석을 통하여 성장된 탄소나노튜브의 구조적 특성을 알아보았다.

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Study on the superhydrophilicity of $TiO_2$ films on glasses by thermal CVD

  • Choi, Jin-Woo;Cho, Sang-Jin;Nam, Sang-Hun;Kim, Young-Dok;Boo, Jin-Hyo
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.02a
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    • pp.100-100
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    • 2010
  • Hydrophilic $TiO_2$ films were deposited on slide glasses using titanium tetraisopropoxide (TTIP) as a precursor by metal-organic chemical vapor deposition (MOCVD). The temperature of substrate was $400^{\circ}C$ and the temperatures of precursor were kept at $75^{\circ}C$ (sample A) and $60^{\circ}C$ (sample B) during the $TiO_2$ film growth. The deposited $TiO_2$ films were characterized by contact angle measurement and uv/vis spectroscopy. The result show that sample B has very low contact angle of almost zero due to superhydrophilic $TiO_2$ surface and transmittance is $76.85%{\pm}1.47%$ at the range of 400 - 700 nm. So, this condition is very optimal for hydrophilic $TiO_2$ film deposition. However, when the temperature of precursor is lower is lower than $50^{\circ}C$ or higher than $75^{\circ}C$, $TiO_2$ could not be deposited on the substrate and cloudy $TiO_2$ film was formed due to low precursor temperature and the increase of surface roughness, respectively.

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Geometrical and Electronic Structure of Epitaxial Graphene on SiC(0001) : A Scanning Tunneling Microscopy Study

  • Ha, Jeong-Hoon;Yang, Hee-Jun;Baek, Hong-Woo;Chae, Jung-Seok;Hwang, Beom-Yong;Kuk, Y.
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.02a
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    • pp.368-368
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    • 2010
  • Monolayers of graphite can be grown by fine controlled surface graphitization on the surfaces of various metallic and semiconducting materials. Epitaxial graphene grown on polished silicon carbide crystal surfaces has drawn much attention due to well known vacuum annealing procedures from surface analysis methods, especially scanning tunneling microscopy(STM) and scanning tunneling spectroscopy(STS). In this study, we have grown single layer and few layer graphene on silicon terminated 6H-SiC(0001) crystals. The growth of graphene layers were observed by low energy electron diffraction(LEED) patterns. Scanning tunneling microscopy and spectroscopy measurements were performed to illustrate the electronic structure which may display some clue on the influence of the underlying structure. Spatially resolved STS results acquired at the edges of epitaxial graphene show in detail the electron density of states, which is compared to theoretical calculations. STM measurements were also done on graphene films grown by chemical vapor deposition(CVD) and transferred onto a SiC(0001) crystal. These observations may provide a hint for the understanding of carrier scattering at the edges.

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