Browsing by Author "Lai, Rui-Ling"

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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-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
;
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.
Field emission improvement through structure of intermixture of long and short carbon nanotubes
(2007-02-01)
Juan, Chuan-Ping
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Lin, Kao-Chao
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Lai, Rui-Ling
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Chang, Kuo-Jui
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Cheng, Huang-Chung
A novel density control With a Structure of an intermixture of long and short carbon nanotubes (CNTs) is first obtained by precisely controlling pretreatment time and hydrogen content. This unique Structure of CNTs is probably due to the uniform distribution of large and small iron nanoparticles under optimum Pretreatment condition. Scanning electron microscopy is performed to confirm the morphology of catalytic nanoparticles after pretreatment. The obtained results show that a low turn-on field (similar to 2.2 V/mu m) and an ultra high field emission Current density (0.4 A/cm(2) at 6.46 V/mu m) can be achieved through this novel structure of CNTs.
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
;
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.
Improvement of luminescent uniformity via synthesizing the carbon nanotubes on a Fe-TiCo-deposited catalytic layer
(2007-02-01)
Cheng, Huang-Chung
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Lai, Rui-Ling
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Chang, Yao-Ren
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Lin, Kao-Chao
;
Juan, Chuan-Ping
Uniformity has been considered to be one of the most important criteria for carbon nanotubes (CNTs) to be utilized as the emitters in field-emission displays (FEDs) or backlight units (BLUs). Using co-deposited Fe and Ti film as a catalyst, a uniform distribution of catalytic nanoparticles was obtained after hydrogen pretreatment as compared with nanoparticles obtained only using a pure Fe film. It might be attributed to the suppression of coalescence of the Fe nanoparticles in the codeposited Fe-Ti film during the CNTs growth. In addition, the length variation of the CNTs synthesized by thermal-chemical vapor deposition (thermal-CVD) was also remarkably Suppressed. This resulted in a significant improvement of the luminescent uniformity, and homogeneous light emission was obtained front the CNTs at 700 V.
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.
Properties of carbon nanotubes via a thin Ti capping layer on the pretreated catalyst
(2007)
Lai, Rui-Ling
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Shiu, Jiun-Kai
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Chang, Yao-Ren
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Lin, Kao-Chao
;
Chang, Pei-Chi
Screening effect and reliability are two of the most important issues in carbon nanotube-based field-emission devices. A thin Ti capping layer has been deposited on the hydrogen-pretreated catalytic iron nanoparticles to control the density of subsequently grown carbon nanotubes. In this way, the screening effect can be remarkably reduced due to the density of carbon nanotubes down to 10(7) from 10(9) cm(-2) as compared to the control specimens. Thus, the turn-on field can be improved to be 2.1 from 3.8 V/mu m at the emission current density of 10 mu A/cm(2). Furthermore, the electrical breakdown field can be increased to more than 7 V/mu m and the lifetime of carbon nanotubes at high electric field (10 V/mu m) can be greatly prolonged from a few seconds to more than 1 h. This can be attributed to better adhesion and lower contact resistance between the carbon nanotubes and the substrate. (c) 2007 The Electrochemical Society. All rights reserved.
The reliability improvements of carbon nanotubes emitters by utilizing an Fe-Ti codeposited catalyst
(2007-08-01)
Lai, Rui-Ling
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Shiu, Jiun-Kai
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Chang, Yao-Ren
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Lin, Kao-Chao
;
Chang, Pei-Chi
In this report, carbon nanotubes (CNTs) partially immersed into the codeposited metal layer have been synthesized by utilizin- an Fe-Ti codeposited catalyst in a thermal -chemical vapor deposition system. This structure could enlarge the contact area between CNTs and substrates to provide better adhesion properties than that in the case of CNTs synthesized from a pure Fe film. Therefore, an abrupt decrease in emission current due to mechanical destruction at a high electric field and a gradual degradation in emission current due to Joule heating were remarkably suppressed. A stable emission current of about 30mA/cm(2) at 7.7 V/mu m for 2,500 s was obtained without obvious degradation.