Browsing by Author "Juan, Chuan-Ping"

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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
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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
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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
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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.
Coaxial-Structured Solar Cells with Silicon Nanostructures
(2012)
Li, Hung-Hsien
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Chen, Kuan-Heng
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Chiou, Si-Ming
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Liu, Han-Wen
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Juan, Chuan-Ping
Coaxial-structured solar cells with different lengths silicon nanowires (SiNWs) fabricated by e-beam lithography and transformer coupled plasma reactive ion etching (TCP-RIE) were demonstrated in this paper. With the intrinsic amorphous silicon thickness of 15 nm and n-layer thickness of 25 nm, the short-current density and the conversion efficiency of the flat film solar cell were 17.58 mA/cm(2) and 3.16 %, respectively. Furthermore, the short-current density increased from 20.75 to 27.90 mA/cm(2) and the conversion efficiency increased from 3.59 to 4.69 % when the silicon nanowires length was increased from 0.5 to 1 mu m. The proposed coaxial-structured solar cells with SiNWs exhibited nearly 48.42 % efficiency enhancement over the plat film solar cell.
Dependence of ferroelectric characteristics on the deposition temperature of (Pb,Sr)TiO3 films
(2007-10-01)
Wang, Jyh-Liang
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Lai, Yi-Sheng
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Shye, Der-Chi
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Chou, Chen-Chia
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Chiou, Bi-Shiou
The pulsed laser deposition (PLD) of (Pb,Sr)TiO3 (PSrT) films on Pt/SiO2/Si at low substrate temperatures (T-s, ranging from 300 to 450 degrees C, has been investigated. The PLD PSrT films prepared at low Ts exhibit ferroelectric proper-ties, good crystallinity, and no significant interdiffusion between the PSrT film and the Pt bottom electrode. The conduction mechanism is identified as Schottky emission at low electric fields and as Poole-Frenkel emission at high electric fields. PSrT films grown at appropriate T, yield fewer interface states and fewer trapping states, leading to a smaller leakage current. The enhanced (100) preferred orientation of PSrT films deposited at T-s= 350-400 degrees C exhibits optimum ferroelectricity. In addition, the dielectric constant and ferroelectricity are associated with the preferred orientation. This shows that the electrical characteristics strongly rely on the preferred orientation and trapping states, which could be controlled by varying the substrate temperature (T, <= 450 degrees C during PLD.
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.
Field Emission Properties of Carbon Nanotube Arrays on the Thickness-Controlled Flexible Substrate by the Pattern Transfer Process
(2012-07-01)
Chang, Chia-Tsung
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Juan, Chuan-Ping
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Lin, Yi-Chan
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Li, Yu-Ren
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Tsai, Wan-Lin
A technigal with the polydimethylsiloxane (PDMS) solution infiltrated into the SiOx-coated CNTAs has been utilized to directly transfer the CNTAs away from the silicon substrate. The oxide coating layer was utilized to protect the morpholgy of as-grown patterned vertical aligmed carbon nanotube (CNTs) arrays. The high density plasma reactive ions etching (HDP-RIE) system was used to make the CNTs emerge from the surface of the flexible substrate and modify the crystallines of CNTs. After the protecting oxide was HDP-RIE-processed for 8 min, the emission current properties were enhanced to be 1.03 V/mu m and 1.43 V/mu m, respectively, for the turn-on field and the threshold field, as compared with 1.25 V/mu m and 1.59 V/mu m for the as-grown CNTs, accordingly. The Field Emission (FE) enhancement after dry etching could be attributed to the open-ended structures and better crystalline.
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.
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
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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 Height Dependence of Field-Emission Properties in an Array of Carbon Nanotube Pillars
(2013-08-01)
Chang, Chia-Tsung
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Juan, Chuan-Ping
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Cheng, Huang-Chung
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Carbon nanotube pillars with optimal field-emission properties, including a high field enhancement factor beta of 5384 and a low turn-on field E-to of 0.84 V/mu m, have been achieved when the ratio of interpillar spacing to pillar height is 2. However, when this ratio exceeds 2, the field enhancement factor increases with increasing pillar height since the field can be enhanced by increasing the aspect ratio. When the ratio is smaller than 2, the field enhancement factor decreases with increasing pillar height owing to the increased field-screening effect. A simulation has been performed to verify the experimental results. (C) 2013 The Japan Society of Applied Physics
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
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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.
Polarization degradation and breakdown of pulse-laser-deposited (Pb,Sr)TiO3 films at low temperatures
(2007-01-01)
Wang, Jyh-Liang
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Shye, Der-Chi
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Lai, Yi-Sheng
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Tseng, Huai-Yuan
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Juan, Chuan-Ping
(Pb,Sr)TiO3 (PST) films were deposited on Pt/SiO2/Si by pulsed laser deposition at low substrate temperatures (T-s) ranging from 300 to 450 degrees C. The loss in remnant polarization (P-r) and coercive field (E-c) is found to be less than 17% after 10(10) switching cycles when T-s is higher than 350 degrees C. It is also suggested that the leakage current is reduced when T-s increases up to a temperature of 400 degrees C. However, PST films deposited at 450 degrees C may produce serious Pb-O volatilization, resulting in the deterioration of the crystallinity and high leakage currents. As a result, the 400 degrees C-deposited PST film reveals the lowest leakage current, nearly fatigued-free J-E characteristics after 10(10) switching cycles, and the best breakdown property, attributed to the enhanced crystallinity and low concentration of defects.
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
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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.
Study on fatigue and breakdown properties of Pt/(Pb,Sr)TiO3/Pt capacitors
(2006-11-22)
Wang, Jyh-Liang
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Lai, Yi-Sheng
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Chiou, Bi-Shiou
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Tseng, Huai-Yuan
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Tsai, Chun-Chien
Pulsed- laser deposited ( Pb, Sr) TiO3 ( PSrT) films on Pt/ SiO2/ Si substrate at various ambient oxygen pressures ( P-O2) are investigated in this work. Films deposited at P-O2 below 100 mTorr exhibit the ( 100) preferred orientation and a tetragonal structure with larger tetragonality. In addition, films deposited at 80 mTorr exhibit the most apparent ferroelectric properties in contrast to those deposited at 200 mTorr. Moreover, films deposited at higher P-O2 also exhibit longer lifetimes and higher breakdown fields due to their smaller leakage current density, in terms of the reduction of defects, compensation of oxygen vacancies (OVs), an improved interface and small cluster sizes. An energy band model reveals that fatigue properties of PSrT films are dominated by interfacial states at low P-O2 and by deep trapping states at high P-O2, which could be ascribed to OVs located at the interfaces and inside films, respectively.
Zinc oxide thin-film transistors fabricated via low-temperature hydrothermal method
(2013-09-01)
Wang, Jyh-Liang
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Yang, Po-Yu
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Juang, Miin-Horng
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Hsieh, Tsang-Yen
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Hwang, Chuan-Chou
Transparent high-performance ZnO TFTs have been fabricated via low-temperature hydrothermal method. The dip of H3PO4 solution prior to the hydrothermal process can form the under-cut AZO seed layer and benefit for the control of ZnO growth. While the use of under-cut AZO seed layer with proper design of channel length, the lateral ZnO growth can be artificially controlled in the desired location to make a continuous active-layer and nearly single one vertical grain boundary cross to the current flow in the channel region. ZnO TFTs indicate the behavior of n-channel enhancement-mode devices. The optimum design of channel length (i.e. L=10 mu m) can provide enough space for the lateral growth of large ZnO grains with less channel defects and bring about the advanced device characteristics (i.e. the positive threshold voltage of 3.0 V, mobility of 9.03 cm(2)/V.s, on/off current ratio >10(6), gate leakage of <1 nA with less fluctuation, and extremely high drain current >500 mu A). (C) 2012 Elsevier B.V. All rights reserved.