Browsing by Author "Chen, Hsia-Wei"

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A quasi-planar thin film field emission diode
(2007-11-01)
Lin, Kao-Chao
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Juan, Chuan-Ping
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Lai, Rui-Ling
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Chen, Hsia-Wei
;
Syu, Yu-Ying
A novel quasi-planar thin-film field emitter is fabricated by thin-film deposition and wet etching processes. The spacing between the emitters and collectors could be well controlled on the basis of the thicknesses of Cr thin films, which create submicron gaps. A forming process increases emitter surface roughness and results in a higher field enhancement factor, which shows better field emission characteristics. The turn-on voltage (at which the current level is 100 nA) of the device with a Cr thin film thickness of 300 nm is as low as 12 V, and the current fluctuation in I hour test at a driving voltage of 20 V represents a variation from -86 to +114%.
Carbon nanotubes synthesized at low temperature and a novel self-focusing gated field emission device
(2008)
Hsu, Yu-Ying
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Lin, Kao-Chao
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Chen, Hsia-Wei
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Juan, Chuan-Ping
;
Cheng, Huang-Chung
A method for synthesis of CNTs at low temperature using thermal CVD is proposed. A multi-layered catalyst, Co/Ti/Al, has been successfully utilized to synthesize carbon nanotubes at 500 square by thermal CVD via modifying the flow rate of reaction gases. The flow rates of ethylene, hydrogen, and nitrogen are determined to he 125, 10, and 1000 sccm to improve the growth and field emission characteristics of CNTs at low temperature. Moreover, a novel self-focusing gated device was proposed to resolve the problem of electron beam divergence.
Carbon-nanotube-based field emission devices with a self-focusing gate structure
(2008)
Lin, Kao-Chao
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Chen, Hsia-Wei
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Juan, Chuan-Ping
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Lai, Rui-Ling
;
Hsu, Yu-Ying
Field-emission devices with a novel self-focusing gate structure using carbon nanotubes as emitters have been fabricated. Without additional focusing electrodes, the self-focusing gate structure employed a pair of gate electrodes parallel with the vicinity of emitters, which resulted in an asymmetric emission area as compared with the conventional gate structure. Therefore, electrons emitted from the emitters gave rise to an overlapping region on the anode plate so that a reduction of spot size had been achieved. According to the simulation results and luminescent images, this self-focusing gate structure had good control of the trajectory of electrons and therefore showed a smaller luminescent spot size than the conventional one. This gate structure, which utilizes a simple fabrication process, has the advantages of low-cost manufacturing and large-area scalability, and therefore is promising for application in field emission displays. (c) 2008 The Electrochemical Society.
Growth and field emission characteristics of carbon nanotubes using Co/Cr/Al multilayer catalyst
(2007-07-01)
Cheng, Huang-Chung
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Lin, Kao-Chao
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Tai, Han-Chung
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Juan, Chuan-Ping
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Lai, Rui-Ling
A multilayer catalyst, Co/Cr/Al, was employed to synthesize carbon nanotubes (CNTs) at atmospheric pressure by thermal chemical vapor deposition (thermal CVD). The relative growth rates, calculated on the basis of the average lengths of nanotubes grown at different temperatures, were utilized to estimate an activation energy of 0.84eV for the multilayer catalyst. Such a low activation energy implies that the nucleation and growth of nanombes could be effectively enhanced via the multilayer catalyst due to the well-distributed small catalytic nanoparticles by Al supporting layer and higher activity by Cr co-catalyst layer. It was also found that nanotubes grown using this configuration at 500 degrees C exhibited excellent field emission characteristics, and showed a highly uniform emission image in a phosphor-coated anode plate.
Pillar-shaped carbon nanotubes by Ti-Fe codeposition
(2007)
Chang, Pei-Chi
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Lai, Rui-Ling
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Lee, Chien-Ying
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Lin, Kao-Chao
;
Chen, Hsia-Wei
In this report, the pillar-shaped carbon nanotubes (CNTs) have been achieved by utilizing an Fe-Ti codeposited layer as catalyst in thermal chemical vapor deposition system (T-CVD). By adjusting the ratio of distance between neighboring pillars (R) to the pillar height (H) as 2.5, the field emission characteristics can be effectively improved by reducing the screening effect. The turn-on field was remarkably decreased to 0.95 V/um with a very high current of 4.98mA for a device with area of 0.02cm(2). The coefficient of variation (CV) of the emission current was as low as 20.59% at 800V for 3600sec.
Study on carbon nanotubes synthesized at low temperatures using multilayerd catalytic films
(2007)
Chen, Hsia-Wei
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Lin, Kao-Chao
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Leou, Yaw-Shing
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Hsu, Yu-Ying
;
Chung, Pei-Chi
CNTs was synthesized using multilayered catalytic films as catalysts at temperatures lower than softening point of soda-lime glass by thermal CVD. It is found that herd good field emission properties and morphologies. The field emission current density of CNTs could reach 29 mA/cm(2) at the electric field of 6 V/um.