• Title, Summary, Keyword: carbon nanowires

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Routes to Improving Performance of Solution-Processed Organic Thin Film Transistors

  • Li, Flora M.;Hsieh, Gen-Wen;Nathan, Arokia;Beecher, Paul;Wu, Yiliang;Ong, Beng S.;Milne, William I.
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.1051-1054
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    • 2009
  • This paper investigates approaches for improving effective mobility of organic thin film transistors (OTFTs). We consider gate dielectric optimization, whereby we demonstrated >2x increase in mobility by using a silicon-rich silicon nitride ($SiN_x$) gate dielectric for polythiophene-based (PQT) OTFTs. We also engineer the dielectric-semiconductor ($SiN_x$-PQT) interface to attain a 27x increase in mobility (up to 0.22 $cm^2$/V-s) using an optimized combination of oxygen plasma and OTS SAM treatments. Augmentative material systems by combining 1-D nanomaterials (e.g., carbon nanotubes, zinc oxide nanowires) in an organic matrix for nanocomposite OTFTs provided a further boost in device performance.

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Electrosynthesis and Electrochemical Properties of Metal Oxide Nano Wire/ P-type Conductive Polymer Composite Film

  • Siadat, S.O. Ranaei
    • Journal of Electrochemical Science and Technology
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    • v.6 no.3
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    • pp.81-87
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    • 2015
  • This study introduces a facile strategy to prepare metal oxide/conducting polymer nanocomposites that may have promising applications in energy storage devices. Ploy aniline/nano wire manganese dioxide (PANI/NwMnO2) was synthesized by cyclic voltammetry on glassy carbon electrode. Morphology and structure of the composite, pure PANI, MnO2 nanowires were fully characterized using XRD and SEM analysis. Electrochemical studies shows excellent synergistic effect between PANI and MnO2 nanowires which results in its capacitance increase and cycle stability against PANI electrode. Specific capacitances of PANI/NwMnO2 and PANI were 456 and 190 F/g respectively. The electrochemical performance of electrodes studied using cyclic voltammetry, Galvanostatic charge/discharge and impedance spectroscopy.

Recent Trends in Development of Ag Nanowire-based Transparent Electrodes for Flexible·Stretchable Electronics (유연·신축성 전자 소자 개발을 위한 은 나노와이어 기반 투명전극 기술)

  • Kim, Dae-Gon;Kim, Youngmin;Kim, Jong-Woong
    • Journal of the Microelectronics and Packaging Society
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    • v.22 no.1
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    • pp.7-14
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    • 2015
  • Recently, advances in nano-material researches have opened the door for various transparent conductive materials, which include carbon nanotube, graphene, Ag and Cu nanowire, and printable metal grids. Among them, Ag nanowires are particularly interesting to synthesize because bulk Ag exhibits the highest electrical conductivity among all metals. Here we reviewed recently-published research works introducing various devices from organic light emitting diode to tactile sensing devices, all of which are employing AgNW for a conducting material. They proposed methods to enhance the stretchability and reversibility of the transparent electrodes, and apply them to make various flexible and stretchable electronics. It is expected that Ag nanowires are applicable to a wide range of high-performance, low-cost, stretchable electronic devices.

Synthesis of Si Nanowire/Multiwalled Carbon Nanotube Core-Shell Nanocomposites (실리콘 나노선/다중벽 탄소나노튜브 Core-Shell나노복합체의 합성)

  • Kim, Sung-Won;Lee, Hyun-Ju;Kim, Jun-Hee;Son, Chang-Sik;Kim, Dong-Hwan
    • Korean Journal of Materials Research
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    • v.20 no.1
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    • pp.25-30
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    • 2010
  • Si nanowire/multiwalled carbon nanotube nanocomposite arrays were synthesized. Vertically aligned Si nanowire arrays were fabricated by Ag nanodendrite-assisted wet chemical etching of n-type wafers using $HF/AgNO_3$ solution. The composite structure was synthesized by formation of a sheath of carbon multilayers on a Si nanowire template surface through a thermal CVD process under various conditions. The results of Raman spectroscopy, scanning electron microscopy, and high resolution transmission electron microcopy demonstrate that the obtained nanocomposite has a Si nanowire core/carbon nanotube shell structure. The remarkable feature of the proposed method is that the vertically aligned Si nanowire was encapsulated with a multiwalled carbon nanotube without metal catalysts, which is important for nanodevice fabrication. It can be expected that the introduction of Si nanowires into multiwalled carbon nanotubes may significantly alter their electronic and mechanical properties, and may even result in some unexpected material properties. The proposed method possesses great potential for fabricating other semiconductor/CNT nanocomposites.

A Study on the Carbon Nanotube Cartridges Using Electric Field (전기장을 이용한 탄소나노튜브 카트리지 연구)

  • Choi J.S.;Kwak Y.K.;Kim S.H.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.1164-1167
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    • 2005
  • This paper is about the carbon nanotube(CNT) samples called as CNT cartridges. The CNT cartridges are useful to make it better to fabricate the nano-sized devices like nanoprobes and nanotweezers through physical attachment. To make these cartridges, we need to align CNTs and to purify them from raw material. There is a variety of methods to align 1-dimensional nanostructures like nanotubes and nanowires. In this review, we mainly focused on the methods using electric field. And we will introduce various researches in relation to the CNT cartridges and the fabrication methods using the CNT cartridges and nanomanipulation techniques.

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Synthesis of Uniformly Doped Ge Nanowires with Carbon Sheath

  • Kim, Tae-Heon;;Choe, Sun-Hyeong;Seo, Yeong-Min;Lee, Jong-Cheol;Hwang, Dong-Hun;Kim, Dae-Won;Choe, Yun-Jeong;Hwang, Seong-U;Hwang, Dong-Mok
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.289-289
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    • 2013
  • While there are plenty of studies on synthesizing semiconducting germanium nanowires (Ge NWs) by vapor-liquid-solid (VLS) process, it is difficult to inject dopants into them with uniform dopants distribution due to vapor-solid (VS) deposition. In particular, as precursors and dopants such as germane ($GeH_4$), phosphine ($PH_3$) or diborane ($B_2H_6$) incorporate through sidewall of nanowire, it is hard to obtain the structural and electrical uniformity of Ge NWs. Moreover, the drastic tapered structure of Ge NWs is observed when it is synthesized at high temperature over $400^{\circ}C$ because of excessive VS deposition. In 2006, Emanuel Tutuc et al. demonstrated Ge NW pn junction using p-type shell as depleted layer. However, it could not be prevented from undesirable VS deposition and it still kept the tapered structures of Ge NWs as a result. Herein, we adopt $C_2H_2$ gas in order to passivate Ge NWs with carbon sheath, which makes the entire Ge NWs uniform at even higher temperature over $450^{\circ}C$. We can also synthesize non-tapered and uniformly doped Ge NWs, restricting incorporation of excess germanium on the surface. The Ge NWs with carbon sheath are grown via VLS process on a $Si/SiO_2$ substrate coated 2 nm Au film. Thin Au film is thermally evaporated on a $Si/SiO_2$ substrate. The NW is grown flowing $GeH_4$, HCl, $C_2H_2$ and PH3 for n-type, $B_2H_6$ for p-type at a total pressure of 15 Torr and temperatures of $480{\sim}500^{\circ}C$. Scanning electron microscopy (SEM) reveals clear surface of the Ge NWs synthesized at $500^{\circ}C$. Raman spectroscopy peaked at about ~300 $cm^{-1}$ indicates it is comprised of single crystalline germanium in the core of Ge NWs and it is proved to be covered by thin amorphous carbon by two peaks of 1330 $cm^{-1}$ (D-band) and 1590 $cm^{-1}$ (G-band). Furthermore, the electrical performances of Ge NWs doped with boron and phosphorus are measured by field effect transistor (FET) and they shows typical curves of p-type and n-type FET. It is expected to have general potentials for development of logic devices and solar cells using p-type and n-type Ge NWs with carbon sheath.

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Recent Trends in Human Motion Detection Technology and Flexible/stretchable Physical Sensors: A Review

  • Park, Inkyu
    • Journal of Sensor Science and Technology
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    • v.26 no.6
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    • pp.391-396
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    • 2017
  • Human body motion detection is important in several industry sectors, such as entertainment, healthcare, rehabilitation, and so on. In this paper, we first discuss commercial human motion detection technologies (optical markers, MEMS acceleration sensors, infrared imaging, etc.) and then explain recent advances in the development of flexible and stretchable strain sensors for human motion detection. In particular, flexible and stretchable strain sensors that are fabricated using carbon nanotubes, silver nanowires, graphene, and other materials are reviewed.

Preparation of Gallium Nitride Powders and Nanowires from a Gallium(III) Nitrate Salt in Flowing Ammonia

  • Jung, Woo-Sik
    • Bulletin of the Korean Chemical Society
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    • v.25 no.1
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    • pp.51-54
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    • 2004
  • Gallium nitride (GaN) powders were prepared by calcining a gallium(III) nitrate salt in flowing ammonia in the temperature ranging from 500 to 1050 $^{\circ}C$. The process of conversion of the salt to GaN was monitored by X-ray diffraction and $^{71}Ga$ MAS (magic-angle spinning) NMR spectroscopy. The salt decomposed to ${\gamma}-Ga_2O_3$ and then converted to GaN without ${\gamma}-{\beta}Ga_2O_3$ phase transition. It is most likely that the conversion of ${\gamma}-Ga_2O_3$ to GaN does not proceed through $Ga_2O$ but stepwise via amorphous gallium oxynitride ($GaO_xN_y$) as intermediates. The GaN nanowires and microcrystals were obtained by calcining the pellet containing a mixture of ${\gamma}-Ga_2O_3$ and carbon in flowing ammonia at 900 $^{\circ}C$ for 15 h. The growth of the nanowire might be explained by the vapor-solid (VS) mechanism in a confined reactor. Room-temperature photoluminescence spectra of as-synthesized GaN powders obtained showed the emission peak at 363 nm.

Highly Stretchable and Sensitive Strain Sensors Fabricated by Coating Nylon Textile with Single Walled Carbon Nanotubes

  • Park, Da-Seul;kim, Yoonyoung;Jeong, Soo-Hwan
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.363.2-363.2
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    • 2016
  • Stretchable strain sensors are becoming essential in diverse future applications, such as human motion detection, soft robotics, and various biomedical devices. One of the well-known approaches for fabricating stretchable strain sensors is to embed conductive nanomaterials such as metal nanowires/nanoparticles, graphene, conducting polymer and carbon nanotubes (CNTs) within an elastomeric substrate. Among various conducting nanomaterials, CNTs have been considered as important and promising candidate materials for stretchable strain sensors owing to their high electrical conductivity and excellent mechanical properties. In the past decades, CNT-based strain sensors with high stretchability or sensitivity have been developed. However, CNT-based strain sensors which show both high stretchability and sensitivity have not been reported. Herein, highly stretchable and sensitive strain sensors were fabricated by integrating single-walled carbon nanotubes (SWNTs) and nylon textiles via vacuum-assisted spray-layer-by-layer process. Our strain sensors had high sensitivity with 100 % tensile strain (gauge factor ~ 100). Cyclic tests confirmed that our strain sensors showed very robust and reliable characteristic. Moreover, our SWNTs-based strain sensors were easily and successfully integrated on human finger and knee to detect bending and walking motion. Our approach presented here might be route to preparing highly stretchable and sensitive strain sensors with providing new opportunity to realize practical wearable devices.

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Determination of Hydrogen Peroxide on Modified Glassy Carbon Electrode by Polytetrakis(2-aminophenyl)porphyrin Nanowire

  • Jeong, Hae-Sang;Kim, Song-Mi;Seol, Hee-Jin;You, Jung-Min;Jeong, Eun-Seon;Kim, Seul-Ki;Seol, Kyung-Sik;Jeon, Seung-Won
    • Bulletin of the Korean Chemical Society
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    • v.30 no.12
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    • pp.2979-2983
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    • 2009
  • Nanowires of polytetrakis(o-aminophenyl)porphyrin (PTAPPNW) were fabricated by electrochemical polymerization with the cyclic voltammetric method in anodic aluminum oxide (AAO) membranes. The glassy carbon electrode (GCE) modified by PTAPPNW, single-walled carbon nanotubes (SWNT) and Nafion as a binder was investigated with voltammetric methods in a phosphate buffer saline (PBS) solution at pH 7.4. The PTAPPNW + SWNT + Nafion/GCE exhibited strongly enhanced voltammetric and amperometric sensitivity towards hydrogen peroxide ($H_2O_2$), which shortened the response time and enhanced the sensitivity for $H_2O_2$ determination at an applied potential of 0.0 V by amperometric method. The PTAPPNW + SWNT + Nafion/GCE can be used to monitor $H_2O_2$ at very low concentrations in biological pH as an efficient electrochemical $H_2O_2$ sensor.