Browsing by Author "Tai, Nyan-Hwa"

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Electron Field Emission Properties of Nanomaterials on Rough Silicon Rods
(2010-01-14)
Wu, Hung-Chi
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Tsai, Tsung-Yen
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Chu, Fu-Hsuan
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Tai, Nyan-Hwa
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Lin, Heh-Nan
Highly porous, individually separated, and vertically aligned rough silicon rods (r-SiRs) were formed via a modified electroless metal deposition (EMD) approach. Despite inheriting the length of crowded silicon nanowires (NWs) obtained by the conventionally adopted EMD method, the r-SiRs are distributed sparsely, subsequently forming an excellent field emitter substrate. The electron field emission (EFE) of carbon nanotubes (CNTs) grown on r-SiRs can be turned on at (E(0))(CNTs/r-SiRs) = 2.3 V/mu m, yielding a high EFE current density, (J(c))(CNTs/r-SiR) = 3.7 mA/cm(2) in an applied field of 5.1 V/mu m, Additionally, a cactuslike structure consisting of zinc oxide NWs on r-SiRs can be turned on at 2.9 V/mu m. The absence of a high-temperature or expensive photolithographic process makes r-SiRs a promising alternative as a silicon base field emitter substrate.
Electron field emission properties on ultra-nano-crystalline diamond coated silicon nanowires
(2008-07-01)
Tzeng, Yu-Fen
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Lee, Chi-Young
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Chiu, Hsin-Tien
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Tai, Nyan-Hwa
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Lin, I-Nan
Ultra-nano-crystal line diamond (UNCD) nano-emitters were prepared by coating UNCD films on the tip of silicon nanowire (SiNW) templates by microwave plasma-enhanced chemical vapor deposition process. The electron field emission properties of the UNCD/SiNW nano-emitters varied markedly with the pre-seeding process for the SiNW-templates. The direct ultrasonication process is more efficient in the formation of the diamond nuclei than the carburization/ultrasonication process, yielding UNCD/SiNWs nano-emitters with better electron field emission properties. The electron field emission can be turned on at (E(0))(UNCD/SiNW4)= 3.75 V/mu m, yielding a large electron field emission current density of (Je)(UNCD/SiNW4)= 11.22 mA/cm(2) at an applied field of 9.75 V/mu m. These characteristics are significantly better than those of bare SiNWs or planar UNCD films. (C) 2008 Elsevier B.V. All rights reserved.
Growth of polycrystalline tubular silicon carbide Yajima-type reaction at the vapor-solid interface
(2007-08-07)
Wang, Chia-Hsin
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Lin, Huang-Kai
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Ke, Tsung-Ying
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Palathinkal, Thomas-Joseph
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Tai, Nyan-Hwa
Polycrystalline tubular SiC on Si is prepared by reacting MeSiHCl2 vapor and Ca thin film on Si at 773-923 K followed by heat treatment at 1273 K. The reaction is a solvent-free Yajima-type process taking place at the vapor-solid interface. The products phase-segregate into a cable-like radial heterostructure composed of a core of CaCl2 and a shell of SiCxHy. After removal of the CaCl2 core, the layer of polycrystalline SiC tubes on Si can emit electrons at a low applied field of 2.5 V/mu m with a current of 10 mu A/cm(2).
Investigations on Diamond Nanostructuring of Different Morphologies by the Reactive-Ion Etching Process and Their Potential Applications
(2013-08-14)
Kunuku, Srinivasu
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Sankaran, Kamatchi Jothiramalingam
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Tsai, Cheng-Yen
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Chang, Wen-Hao
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Tai, Nyan-Hwa
We report the systematic studies on the fabrication of aligned, uniform, and highly dense diamond nanostructures from diamond films of various granular structures. Self-assembled Au nanodots are used as a mask in the self-biased reactive-ion etching (RIE) process, using an O-2/CF4 process plasma. The morphology of diamond nanostructures is a close function of the initial phase composition of diamond. Cone-shaped and tip-shaped diamond nanostructures result for microcrystalline diamond (MCD) and nanocrystalline diamond (NCD) films, whereas pillarlike and grasslike diamond nanostructures are obtained for Ar-plasma-based and N-2-plasma-based ultrananocrystalline diamond (UNCD) films, respectively. While the nitrogen-incorporated UNCD (N-UNCD) nanograss shows the most-superior electron-field-emission properties, the NCD nanotips exhibit the best photoluminescence properties, viz, different applications need different morphology of diamond nanostructures to optimize the respective characteristics. The optimum diamond nanostructure can be achieved by proper choice of granular structure of the initial diamond film. The etching mechanism is explained by in situ observation of optical emission spectrum of RIE plasma. The preferential etching of sp(2)-bonded carbon contained in the diamond films is the prime factor, which forms the unique diamond nanostructures from each type of diamond films. However, the excited oxygen atoms (O*) are the main etching species of diamond film.
Low-temperature CVD growth of carbon nanotubes for field emission application
(2007-03-01)
Chen, Kuang-Chung
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Chen, Chia-Fu
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Lee, Jen-Hao
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Wu, Tai-Lin
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Hwang, Chian-Liang
For field emission application, carbon nanotube emitters were synthesized on catalyst-mixed thick-film electrode lower than 500 degrees C by chemical vapor deposition (CVD) method. Mixtures of Ni/tetraethyl silicate (TEOS) and conducting Ag powders were applied to fabricate the electrode by screen-printing processes. These processes are simple, low cost and easy to scale up for large sized panels. The field emission properties performed uniform emission image and high brightness (no less than 500 nits). The turn-on electric field was about 3.85 V/mu m with an emission current destiny of 10 mu A/cm(2), and the achieved current density was 1 mA/cm(2) driven by 5 V/mu m. (c) 2006 Elsevier B.V. All rights reserved.
Low-temperature CVD growth of carbon nanotubes for field emission application
(2007-03-01)
Chen, Kuang-Chung
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Chen, Chia-Fu
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Lee, Jen-Hao
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Wu, Tai-Lin
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Hwang, Chian-Liang
For field emission application, carbon nanotube emitters were synthesized on catalyst-mixed thick-film electrode lower than 500 degrees C by chemical vapor deposition (CVD) method. Mixtures of Ni/tetraethyl silicate (TEOS) and conducting Ag powders were applied to fabricate the electrode by screen-printing processes. These processes are simple, low cost and easy to scale up for large sized panels. The field emission properties performed uniform emission image and high brightness (no less than 500 nits). The turn-on electric field was about 3.85 V/mu m with an emission current destiny of 10 mu A/cm(2), and the achieved current density was 1 mA/cm(2) driven by 5 V/mu m. (c) 2006 Elsevier B.V. All rights reserved.
Manganese ion implanted ultrananocrystalline diamond films: Optical and electrical characterization
(2019-04-01)
Kunuku, Srinivasu
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Chen, Chien-Hsu
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Hsieh, Ping-Yen
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Lin, Bo-Rong
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Tai, Nyan-Hwa
We report the optical and electrical properties of high-dose (10(15)-10(17) ions/cm(2)) Mn-ion implanted ultrananocrystalline diamond (Mn-UNCD) films. Mn-ion implantation and post-annealing of UNCD films lead to the formation of Mn-related color centers, characterized in Mn-UNCD films by their zero phonon line emissions at 621.2 nm and phonon sidebands at 611.2 nm and 630.3 nm. Raman spectra of Mn-UNCD films indicated amorphization via high-dose Mn-ion implantation and that the annealing process results in graphitization of the films. The Mn-UNCD film implanted with the Mn-ion dose of 1017 ions/cm(2) exhibits a conductivity of 122.25 (Omega cm)(-1), as well as enhanced field electron emission (FEE) properties such as a turn-on field of 10.67 V/mu m and a FEE current density of 0.85 mA/cm(2).
Stacked Silicon Nanowires with Improved Field Enhancement Factor
(2010-02-01)
Tzeng, Yu-Fen
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Wu, Hung-Chi
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Sheng, Pei-Sun
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Tai, Nyan-Hwa
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Chiu, Hsin Tien
This work describes newly structured stacked silicon nanowires (s-SiNWs), consisting of nanosized silicon wires on top of silicon microrods (SiMRs) and exhibiting pronouncedly superior electron held emission (EFE) characteristics to the conventional SiNWs, by using a two-step electroless metal deposition process. Experimental results indicate that for these s-SiNWs, the electrostatic "screen effect" is markedly suppressed and the held enhancement factor (beta-value) is significantly increased ((beta)(s-SiNWs) = 2533). Additionally, the turn-on held (Eo) for triggering the EFE process is reduced to a level comparable with that of carbon nanotubes, viz. (E(0))(s-SiNWs) = 2.0 V/mu m. This simple and robust modified electroless metal deposition approach does not require either a high temperature or an expensive photolithographic process and possesses great potential for applications.
Structural and Electrical Properties of Conducting Diamond Nanowires
(2013-02-27)
Sankaran, Kamatchi Jothiramalingam
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Lin, Yen-Fu
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Jian, Wen-Bin
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Chen, Huang-Chin
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Panda, Kalpataru
Conducting diamond nanowires (DNWs) films have been synthesized by N-2-based microwave plasma enhanced chemical vapor deposition. The incorporation of nitrogen into DNWs films is examined by C Is X-ray photoemission spectroscopy and morphology of DNWs is discerned using field-emission scanning electron microscopy and transmission electron microscopy (TEM). The electron diffraction pattern, the visible-Raman spectroscopy, and the near-edge X-ray absorption fine structure spectroscopy display the coexistence of sp(3) diamond and sp(2) graphitic phases in DNWs films. In addition, the microstructure investigation, carried out by high-resolution TEM with Fourier transformed pattern, indicates diamond grains and graphitic grain boundaries on surface of DNWs. The same result is confirmed by scanning tunneling microscopy and scanning tunneling spectroscopy (STS). Furthermore, the STS spectra of current-voltage curves discover a high tunneling current at the position near the graphitic grain boundaries. These highly conducting regimes of grain boundaries form effective electron paths and its transport mechanism is explained by the three-dimensional (3D) Mott's variable range hopping in a wide temperature from 300 to 20 K. Interestingly, this specific feature of high conducting grain boundaries of DNWs demonstrates a high efficiency in field emission and pave a way to the next generation of high-definition flat panel displays or plasma devices.
Ti5Si3 nanowire and its field emission property
(2008-04-08)
Lin, Huang-Kai
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Tzeng, Yu-Fen
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Wang, Chia-Hsin
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Tai, Nyan-Hwa
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Lin, I-Nan