• Title, Summary, Keyword: Metal oxide chemical vapor deposition

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Effect of few-walled carbon nanotube crystallinity on electron field emission property

  • Jeong, Hae-Deuk;Lee, Jong-Hyeok;Lee, Byung-Gap;Jeong, Hee-Jin;Lee, Geon-Woong;Bang, Dae-Suk;Cho, Dong-Hwan;Park, Young-Bin;Jhee, Kwang-Hwan
    • Carbon letters
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    • v.12 no.4
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    • pp.207-217
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    • 2011
  • We discuss the influence of few-walled carbon nanotubes (FWCNTs) treated with nitric acid and/or sulfuric acid on field emission characteristics. FWCNTs/tetraethyl orthosilicate (TEOS) thin film field emitters were fabricated by a spray method using FWCNTs/TEOS sol one-component solution onto indium tin oxide (ITO) glass. After thermal curing, they were found tightly adhered to the ITO glass, and after an activation process by a taping method, numerous FWCNTs were aligned preferentially in the vertical direction. Pristine FWCNT/TEOS-based field emitters revealed higher current density, lower turn-on field, and a higher field enhancement factor than the oxidized FWCNTs-based field emitters. However, the unstable dispersion of pristine FWCNT in TEOS/N,N-dimethylformamide solution was not applicable to the field emitter fabrication using a spray method. Although the field emitter of nitric acid-treated FWCNT showed slightly lower field emission characteristics, this could be improved by the introduction of metal nanoparticles or resistive layer coating. Thus, we can conclude that our spray method using nitric acid-treated FWCNT could be useful for fabricating a field emitter and offers several advantages compared to previously reported techniques such as chemical vapor deposition and screen printing.

Reflow of copper film for the interconnection of the next generation semiconductor devices (차세대 반도체 소자의 배선을 위한 구리박막의 reflow)

  • 김동원;김갑중;권인호;이승윤;라사균;박종욱
    • Journal of the Korean Vacuum Society
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    • v.6 no.3
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    • pp.206-212
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    • 1997
  • The reflow characteristics of copper, which is expected to be used as interconnection materials in the next generation semiconductor devices, were investigated. Copper films were deposited on hole and trench patterns by metal organic chemical vapor deposition and annealed in nitrogen and oxygen ambient with the annealing temperatures ranging from $350^{\circ}C$ to $550^{\circ}C$. Copper films were not reflowed into the patterns upon the annealing in nitrogen ambient, but reflowed at the annealing temperature higher than $450^{\circ}C$ in oxygen ambient. It is considered that the reflow takes place as the heat generated by the oxidation of copper liquefies the copper film partly and the liquid copper fills the patterns for minimizing the surface energy and the potential energy. Upon the annealing in oxygen ambient, the copper oxide whose thickness was less than 300$\AA$ formed at the surface of an agglomerate and the resistivity of copper film increased drastically at an annealing temperature of $550^{\circ}C$ due to the copper agglomeration.

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Formation of SiOF Thin Films by FTES/$O_2$-PECVD Method (FTES/$O_2$-PECVD 방법에 의한 SiOF 박막형성)

  • Kim, Duk-Soo;Lee, Ji-Hyeok;Lee, Kwang-Man;Gang, Dong-Sik;Choe, Chi-Kyu
    • Korean Journal of Materials Research
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    • v.9 no.8
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    • pp.825-830
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    • 1999
  • Characteristics of SiOF films deposited by a FTES/$O_2$-plasma enhanced chemical vapor deposition method have been investigated using Fourier transform infrared spectroscopy, X-ray photoelectro spectroscopy, and ellipsometry. Electrical properties such as dielectric constant, dielectric breakdown and leakage current density are investigated using C-V and I-V measurements with MIS(Au/SiOF/p-Si) capacitor structure. Stepcoverage of the films have been also characterized using scanning electron microscopy and ellipsometry. A high quality SiOF film was formed on that the flow rates of FTES and $O_2$were 300sccm, respectively. The dielectric constant of the deposited SiOF film was about 3.1. This value is lower than that of the oxide films obtained using other method. The dielectric breakdown field and leakage current are more than 10MV/cm and about $8[\times}10^{9}A/\textrm{cm}^2$, respectively. The deposited SiOF film with thickness as $2500{\AA}$ on the $0.3{\mu}{\textrm}{m}$ metal pattern shows a high step-coverage without a void.

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Intracellular Electrical Stimulation on PC-12 Cells through Vertical Nanowire Electrode

  • Kim, Hyungsuk;Kim, Ilsoo;Lee, Jaehyung;Lee, Hye-young;Lee, Eungjang;Jeong, Du-Won;Kim, Ju-Jin;Choi, Heon-Jin
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.407-407
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    • 2014
  • Nanotechnology, especially vertically grown silicon nanowires, has gotten great attentions in biology due to characteristics of one dimensional nanostructure; controllable synthetic structure such as lengths, diameters, densities. Silicon nanowires are promising materials as nanoelectrodes due to their highly complementary metal-oxide-semiconductor (CMOS) - and bio-compatibility. Silicon nanowires are so intoxicated that are effective for bio molecular delivery and electrical stimulation. Vertical nanowires with integrated Au tips were fabricated for electrical intracellular interfacing with PC-12 cells. We have made synthesized two types of nanowire devices; one is multi-nanowires electrode for bio molecular sensing and electrical stimulation, and the other is single-nanowires electrode respectively. Here, we demonstrate that differentiation of Nerve Growth Factor (NGF) treated PC-12 cells can be promoted depending on different magnitudes of electrical stimulation and density of Si NWs. It was fabricated by both bottom-up and top-down approaches using low pressure chemical vapor deposition (LPCVD) with high vacuuming environment to electrically stimulate PC-12 cells. The effects of electrical stimulation with NGF on the morphological differentiation are observed by Scanning Electron Microscopy (SEM), and it induces neural outgrowth. Moreover, the cell cytosol can be dyed selectively depending on the degree of differentiation along with fluorescence microscopy measurement. Vertically grown silicon nanowires have further expected advantages in case of single nanowire fabrication, and will be able to expand its characteristics to diverse applications.

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SnO2 Nanowire Networks on a Spherical Sn Surface: Synthesis and NO2 sensing properties (구형 Sn 표면의 SnO2 나노와이어 네트워크: 합성과 NO2 감지 특성)

  • Pham, Tien Hung;Jo, Hyunil;Vu, Xuan Hien;Lee, Sang-Wook;Lee, Joon-Hyung;Kim, Jeong-Joo;Heo, Young-Woo
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • pp.142.2-142.2
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    • 2018
  • One-dimensional metal oxide nanostructures have attracted considerable research activities owing to their strong application potential as components for nanosize electronic or optoelectronic devices utilizing superior optical and electrical properties. In which, semiconducting $SnO_2$ material with wide-bandgap Eg = 3.6 eV at room temperature, is one of the attractive candidates for optoelectronic devices operating at room temperature [1, 2], gas sensor [3, 4], and transparent conducting electrodes [5]. The synthesis and gas sensing properties of semiconducting $SnO_2$ nanomaterials have become one of important research issues since the first synthesis of SnO2 nanowires. In this study, $SnO_2$ nanowire networks were synthesized on a basis of a two-step process. In step 1, Sn spheres (30-800 nm in diameter) embedded in $SiO_2$ on a Si substrate was synthesized by a chemical vapor deposition method at $700^{\circ}C$. In step 2, using the source of these Sn spheres, $SnO_2$ nanowire (20-40 nm in diameter; $1-10{\mu}m$ in length) networks on a spherical Sn surface were synthesized by a thermal oxidation method at $800^{\circ}C$. The Au layers were pre-deposited on the surface of Sn spherical and subsequently oxidized Sn surface of Sn spherical formed SnO2 nanowires networks. Field emission scanning electron microscopy and high-resolution transmission electron microscopy images indicated that $SnO_2$ nanowires are single crystalline. In addition, the $SnO_2$ nanowire is also a tetragonal rutile, with the preferred growth directions along [100] and a lattice spacing of 0.237 nm. Subsequently, the $NO_2$ sensing properties of the $SnO_2$ network nanowires sensor at an operating temperature of $50-250^{\circ}C$ were examined, and showed a reversible response to $NO_2$ at various $NO_2$ concentrations. Finally, details of the growth mechanism and formation of Sn spheres and $SnO_2$ nanowire networks are also discussed.

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Characteristics of 32 × 32 Photonic Quantum Ring Laser Array for Convergence Display Technology (디스플레이 융합 기술 개발을 위한 32 × 32 광양자테 레이저 어레이의 특성)

  • Lee, Jongpil;Kim, Moojin
    • Journal of the Korea Convergence Society
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    • v.8 no.5
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    • pp.161-167
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    • 2017
  • We have fabricated and characterized $32{\times}32$ photonic quantum ring (PQR) laser arrays uniformly operable with $0.98{\mu}A$ per ring at room temperature. The typical threshold current, threshold current density, and threshold voltage are 20 mA, $0.068A/cm^2$, and 1.38 V. The top surface emitting PQR array contains GaAs multiquantum well active regions and exhibits uniform characteristics for a chip of $1.65{\times}1.65mm^2$. The peak power wavelength is $858.8{\pm}0.35nm$, the relative intensity is $0.3{\pm}0.2$, and the linewidth is $0.2{\pm}0.07nm$. We also report the wavelength division multiplexing system experiment using angle-dependent blue shift characteristics of this laser array. This photonic quantum ring laser has angle-dependent multiple-wavelength radial emission characteristics over about 10 nm tuning range generated from array devices. The array exhibits a free space detection as far as 6 m with a function of the distance.