Browsing by Author "Chen, Te-Ming"

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Amorphous carbon coated silicon nanotips fabricated by MPCVD using anodic aluminum oxide as the template
(2007)
Chen, Te-Ming
;
Pan, Fu-Ming
;
Hung, Jui-Yi
;
Chang, L.
;
Wu, Shich-Chuan
We have used nanoporous anodic aluminum oxide (AAO) as a template to fabricate amorphous carbon (alpha-C) coated silicon nanotips by microwave plasma chemical vapor deposition (MPCVD). During the preparation of the well-ordered AAO pore channel array, an underlying TiN layer was anodically oxidized as well in the late stage of the AAO anodization, forming titanium oxide nanomasks for Si nanotip fabrication. The titanium oxide nanomasks were then used to transfer the arrangement pattern of the AAO pore channel array to the Si substrate by plasma etch in the MPCVD system and, therefore, a well-ordered Si nanotip array was produced. An alpha-C layer similar to 5 nm thick was in situ deposited on the Si nanotips during the MPCVD process. The alpha-C layer was rich in nanocrystalline graphitic carbons according to Raman and Auger electron spectroscopies. The nanocrystalline graphitic carbons in the coating and the sharp tip shape made the Si nanotip a good field emitter and a field enhancement factor of similar to 659 was obtained. (c) 2007 The Electrochemical Society.
Carbon-Coated Porous Aluminum Oxides Used as Spacer Overlayers to Reduce Secondary Electron Emission for Field Emission Display Applications
(2013-07-01)
Yu, Tung-Yuan
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Pan, Fu-Ming
;
Chen, Cheng-Li
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Chen, Te-Ming
;
Chen, Tsung-Han
Porous surface structures can mitigate the charging effect of vacuum spacers of field-emission flat panel display due to the abundance of secondary electrons (SEs) emitted from the spacers during field emission display (FED) operation. In this study, we fabricated porous anodic aluminum oxide (AAO) overlayers on glass substrates to examine the effect of carbon deposition on the reduction of SE emissions. This paper reports that uniform AAO overlayers can be simultaneously prepared on both sides of a glass plate 2 x 10 cm(2) in size. The SE emission of the AAO overlayer was examined by using an Auger electron microscope. When a small amount of carbon is evaporation-deposited on the as-prepared AAO overlayer, the SE emission efficiency is significantly decreased and the reduction in the SE emission is ascribed to the low SE yield of the carbon deposit and the suppression of SE escape from the narrowed pore channels. However, a heavy deposition of carbon results in a smaller surface roughness of the AAO overlayer, thereby increasing SE emission. The carbon-coated AAO overlayer demonstrates favorable electrical and mechanical properties, making it suitable for use in FED vacuum spacers. (C) 2013 The Japan Society of Applied Physics
Dark current suppression of amorphous selenium based photosensors by the ZnO hole blocking layer
(2014-05-01)
Yu, Tung-Yuan
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Pan, Fu-Ming
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Chang, Cheng-Yi
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Hu, Tien
;
Chen, Jenn-Fang
To study the influence of defects in the hole blocking layer (HBL) on the dark current of amorphous selenium (a-Se) based photosensors, we prepared ZnO thin films by reactive sputter deposition (RSD) for the use as the HBL of the photosensors. The ZnO HBL layers prepared with different oxygen flow rates were characterized by X-ray photoelectron spectroscopy, Raman scattering analysis and photoluminescence, indicating that the density of oxygen vacancies in the ZnO thin films is significantly affected by the oxygen flow rate. The deep level transient spectroscopy measurement reveals two hole trap levels present in the RSD deposited ZnO thin films; one is at 0.94 eV and the other at 0.24 eV above the valence band edge. The electrical performance of the a-Se photosensor is largely influenced by the amount of oxygen vacancies in the ZnO thin film. The a-Se photosensor with the ZnO HBL of the most oxygen vacancies has the lowest dark current and demonstrates the highest breakdown field. (C) 2014 Elsevier B.V. All rights reserved.
Electrocatalytic activity of Pt nanoparticles electrodeposited on amorphous carbon-coated silicon nanocones
(2010-02-01)
Tiwari, Jitendra N.
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Pan, Fu-Ming
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Chen, Te-Ming
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Tiwari, Rajanish N.
;
Lin, Kun-Lin
This study pulse-electrodeposits Pt nanoparticles on amorphous carbon-coated silicon nanocones (ACNCs) and explores them as the electrocatalyst for methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR) for direct methanol fuel cell applications. The work prepares silicon nanocones on the Si wafer using porous anodic aluminum oxide as the template and then deposits the amorphous carbon layer on the nanocones by microwave plasma chemical vapor deposition. According to Raman scattering and X-ray photoelectron spectroscopies (XPS), the surface of the ACNC support is composed of a nanocrystalline graphitic structure. and rich in oxygen-containing adspecies. The Pt nanoparticles pulse-electrodeposited on the highly ordered ACNC support disperses well with a large electrocatalytic surface area. The Pt/ACNC electrode exhibits excellent electrocatalytic activity and stability toward both MOR and ORR. This study suggests the abundant oxygen-containing surface species and the nanometer size of the Pt catalyst as the two major factors enhancing electrocatalytic performance of Pt/ACNC electrode. The XPS Study suggests the occurrence of charge transfer from pi-sites of the graphitic Structure to the Pt nanoparticle, thereby improving the electrochemical stability of the electrode. (C) 2009 Elsevier B.V. All rights reserved.
Fabrication and field-emission characteristics of TiN nanorods with a concave top surface
(2008)
Chen, Te-Ming
;
Hung, Jui-Yi
;
Pan, Fu-Ming
;
Chang, L.
;
Sheu, J. -T.
Well-ordered titanium nitride nanorods were fabricated by reactive ion etch using titanium oxide nanodots as the mask, which were prepared using the anodic aluminum oxide templation method. The TiN nanorods exhibited a concave top surface with a protruding edge. Due to the protruding top edge and a high aspect ratio, the TiN nanorods showed a low turn-on voltage of 1.6 V/mu m. The ellipsoidal cylinder model was used to evaluate the field-enhancement effect of the protruding edge, and an underestimation by similar to 26% was found as compared with the enhancement factor derived from the Fowler-Nordheim plot. (C) 2008 The Electrochemical Society.
Ordered silicon nanocones as a highly efficient platinum catalyst support for direct methanol fuel cells
(2008-08-01)
Tiwari, Jitendra N.
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Chen, Te-Ming
;
Pan, Fu-Ming
;
Lin, Kun-Lin
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材料科學與工程學系
Platinum nanoparticles were electrodeposited on ordered silicon nanocones (SNCs) and used as the catalyst for methanol electro-oxidation in direct methanol fuel cells (DMFCs). Because of uniform dispersion of Pt nanoparticles and the high surface area, the Pt-SNC electrode exhibited superior electrocatalytic properties toward the methanol electro-oxidation, with the onset potential of 0.08 V (vs. SCE). According to chronoamperometric analysis and CO stripping cyclic voltammetric (CV) study, the Pt/SNC electrode had a stable electro-oxidation activity with a very good CO tolerance. The Si surface oxide surrounding the Pt nanoparticles on the SNCs was suggested to play a key role in improving the CO tolerance via the bifunctional mechanism. (c) 2008 Elsevier B.V. All rights reserved.
Pulse Electrodeposition of Iridium Oxide on Silicon Nanotips for Field Emission study
(2009-05-01)
Chen, Te-Ming
;
Hung, Jui-Yi
;
Pan, Fu-Ming
;
Chang, L.
;
Wu, Shich-Chuan
To improve electron field emission properties of anodic aluminum oxide (AAO) templated Si nanotips, IrO(2) nanoparticles were deposited on the nanotips using bipolar pulse electrodeposition method. The IrO(2) nanoparticles had a uniform size distribution with an average value of similar to 4 nm, and well dispersed on the ordered Si nanotips. Due to the small radius and a lower work function, the IrO(2)/Si nanotip exhibited field emission properties better than the bare Si nanotip with a field enhancement factor of similar to 128. The SEM and TEM were utilized to investigate the structure and morphology. The physical and chemical properties were evaluated XRD and X-ray photoelectron spectroscopy (XPS).