Browsing by Author "Chen, KJ"

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Controlling steps during early stages of the aligned growth of carbon nanotubes using microwave plasma enhanced chemical vapor deposition
(2002-10-01)
Chen, LC
;
Wen, CY
;
Liang, CH
;
Hong, WK
;
Chen, KJ
Vertically aligned carbon nanotubes (CNTs) with controllable length and diameter fabricated by microwave plasma enhanced chemical vapor deposition (MPECVD) are of continuing interest for various applications. This paper describes the role of process gas composition as well as the pre-coating catalytic layer characteristics. It is observed that nucleation of CNTs was significantly enhanced by adding nitrogen in the MPECVD process, which also promoted formation of bamboo-like structures. The very first key step toward growth of aligned CNTs was the formation of high-density fine carbon onion encapsulated metal (COEM) particles under a hydrogen plasma. Direct microscopic investigation of their structural evolution during the very early stages revealed that elongation, necking, and splitting of the COEM particles occurred accompanying the growth of CNTs, such that one of the split portions rode on the top of the growing tube while the remaining one resided on the root. Our results suggest that CNTs grow via the "tip-growth" as well as "root-growth" mechanisms.
Fabrication and characterization of carbon nanotube triodes
(2001-05-01)
Hong, WK
;
Chen, KH
;
Chen, LC
;
Tarntair, FG
;
Chen, KJ
To achieve high emission current density, carbon nanotube triodes have been proposed using recessed oxide as the insulator between the gate and the carbon nanotubes to replace the conventional spacer. An anode current of 10 muA was achieved with a gate voltage of 98 V for a nanotube sample prepared with a growth time of 12 min. Carbon nanotubes synthesized with various growth times were analyzed using a scanning electron microscope and Raman spectroscopy. By increasing the growth time, longer carbon nanotubes were obtained. Effects of the length of the carbon nanotubes on the field emission of the triodes are discussed, Enhanced luminance was obtained as the anode voltage increased from 600V to 1000V. Such carbon nanotube triodes are promising for utilization in future field-emission displays.
Fabrication and characterization of lateral field emission device based on carbon nanotubes
(2003)
Tsai, CC
;
Juan, CP
;
Chen, KJ
;
Chen, KH
;
Chen, LC
Fabrication and characterization of low turn-on voltage carbon nanotube field emission triodes
(2001-08-01)
Cheng, HC
;
Chen, KJ
;
Hong, WK
;
Tantair, FG
;
Lin, CP
Based on selective growth, carbon nanotubes (CNTs) for low turn-on voltage field emission triodes have been grown via microwave plasma-enhanced chemical vapor deposition. The triode devices fabricated with standard integrated circuit process contain 4 x 4 emitting cells with extraction gates and each individual cell is 4 mum in diameter. With the phosphor-coated indium tin oxide glass as the anode away from the CNTs triodes with similar to1 mm above, the triode devices achieved low turn-on gate voltage of 30 V and high emission current density of 0.7 A/cm(2) at 50 V. The results exhibit CNTs for potential application in field emission display. (C) 2001 The Electrochemical Society.
Field electron emission from C-based emitters and devices
(2001)
Chen, LC
;
Hong, WK
;
Tarntair, FG
;
Chen, KJ
;
Lin, JB
We present the fabrication, characterization and field emission properties of various C-based emitters and devices, which include (1) the diode-type emitters consisting of arrays of carbon-coated Si microtips and carbon nanotubes (CNTs), (2) CNT triodes. and (3) thin-film-transistor (TFT)-controlled CNT field emission devices (FEDs). All the CNTs were deposited by microwave plasma-enhanced chemical vapor deposition. For the first type, each array contains 50 x 50 emitting cells and each individual cell is 3 microns square. Compared to the Si microtips with bias-assisted carburization or diamond cladding, enhancement in field emission by several orders of magnitude of the CNTs arrays was observed. While the diode-type CNT emitters easily achieve the goal of drawing high electron emission current at low macroscopic field, their long-term stability is not satisfactory for practical applications. For the triode-type CNT-FEDs, vertically aligned CNTs with controlled length were directly grown on the Fe-coated Si substrate pre-patterned by photolithography and etching using oxide as the gate insulator, and the emission current from the CNTs was controlled via the gate voltage. For the TFT-controlled CNT-FEDs, CNTs were selectively grown on the drain region of the TFT and the emission current from the CNTs was controlled via the TFT drain current. It should be mentioned that the fabrication procedures are straightforward and can be integrated with current technologies in the well-established semiconductor industry. Both the triode-type CNTs as well as the TFT-controlled CNT-FEDs have demonstrated improved controllability and stability while maintaining high emission current density.
Improved field-emission properties of carbon nanotube field-emission arrays by controlled density growth,of carbon nanotubes
(2005-01-01)
Juan, CP
;
Chen, KJ
;
Tsai, CC
;
Lin, KC
;
Hong, WK
The density distribution of CNTs is one of the. crucial parameters determing the field-emission property of CNTs. To effectively control the density of CNTs, an inactive thin-film layer was deposited on a catalyst. The results showed that improved field emission property could be obtained with a thin SiO layer on the catalyst layer as the precursor. For 3.5 nm Fe and 3.5 nm SiO on 3.5 nm Fe as a catalyst, the turn-on field could be decreased from 3.7 V/mum. to 2.2 V/mum and the field-emission current density increased from 2.6 x 10(-8) A/cm(2) to 2.4 x 10(-4) A/cm(2) when the applied field was 4 V/mum.
Improvement of field emission characteristics of carbon nanotubes by excimer laser treatment
(2002-10-01)
Chen, KJ
;
Hong, WK
;
Lin, CP
;
Chen, KH
;
Chen, LC
The density of carbon nanotubes (CNTs) deposited by microwave plasma chemical vapor deposition (MPCVD) is extremely high, which results in screening effect in the electric field. To achieve excellent field emission characteristics. an excimer laser treatment (ELT) was introduced to reduce the density of CNTs, Scanning electron microscopy (SEM) micrographs showed reduced densities of the CNTs, and the measurement of electrical characteristics results repealed the improved field emission properties under suitable ELT conditions. The turn-on field decreased from 3 V/mum to 2.1 V/mum. and the emission Current density increased from 5.73 mA/cm(2) to 87.13 mA/cm(2) at the applied field of 5 V/mum.
Integration of thin film transistor controlled carbon nanotubes for field emission devices
(2001-04-01)
Cheng, HC
;
Hong, WK
;
Tarntair, FG
;
Chen, KJ
;
Lin, JB
A new field emission device composed of carbon nanotubes and a thin film transistor (TFT) has been successfully demonstrated to significantly improve emission stability. Carbon nanotubes are directly integrated in the drain region of the TFT and the emission current from the carbon nanotubes is controlled via the TFT drain current. The fluctuation of the emission current of the TFT-controlled carbon nanotubes can be suppressed to less than 2%, below the fluctuation of uncontrolled carbon nanotubes. The novel field emission device exhibits low-voltage controllability, good emission stability, and structural simplicity, making it promising for application to future field-emission display. (C) 2001 The Electrochemical Society.
Low turn-on voltage field emission triodes with selective growth of carbon nanotubes
(2001-11-01)
Chen, KJ
;
Hong, WK
;
Lin, CP
;
Chen, KH
;
Chen, LC
A low turn-on voltage, field emission triode array has been fabricated using the selective deposition of carbon nanotubes (CNTs) in a microwave plasma chemical vapor deposition (MPCVD) system. The field emission triodes exhibited a low turn-on voltage of 13 V and a large emission current of 23 muA with the gate voltage at 60 V. Short-term stress reveals a 10% current fluctuation within 1800 sec. The excellent electric properties suggest that the array shows potential for application in field emission displays and vacuum microelectronics.
Role of extrinsic atoms on the morphology and field emission properties of carbon nanotubes
(2003-06-16)
Chan, LH
;
Hong, KH
;
Xiao, DQ
;
Hsieh, WJ
;
Lai, SH
Extrinsic atoms were doped into multiwalled carbon nanotubes (MWCNTs) using microwave plasma-enhanced chemical vapor deposition. Doped nitrogen atoms alter the original parallel graphenes into highly curved ones including some fullerene-like structures. Doped nitrogen atoms could replace carbon atoms in MWCNTs and therefore increase the electronic density that enhances the electron field emission properties. On the other hand, the incorporation of boron into the carbon network apparently increases the concentration of electron holes that become electron traps and eventually impedes the electron field emission properties. Fowler-Nordheim plots show two different slopes in the curve, indicating that the mechanism of field emission is changed from low to high bias voltages. beta values could be increased by an amount of 42% under low bias voltages and 60% under high bias voltages in the N-doped MWCNTs, but decreased by an amount of 8% under low bias region and 68% under high bias voltage in the B-doped MWCNTs. (C) 2003 American Institute of Physics.
Wafer rework strategies at the photolithography stage
(2001-06-01)
Sha, DY
;
Hsieh, LF
;
Chen, KJ
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
Defective wafers are often seen during the semiconductor manufacturing process. Technically, there is no known remedy for a defective wafer. However, at the photolithography phase of semiconductor manufacturing, the defective wafers can be reworked to reduce the manufacturing cost significantly. In this paper, when comparing the three rework strategies that were proposed by Zargar, we pinpoint the disadvantages of each and offer two other strategies. We assess the advantages and disadvantages of the five rework strategies of each reworked batch according to total cycle time, the quantity of work-in-process, each machine's utilization rate, the utilization rate of photolithography, and the average length of queues for photolithography. Through simulations and statistics, the fifth strategy is shown to be superior to the first four and most suitable for wafer manufacturing. Significance: At the photolithography stage, the processing relation between lot and lot should be considered. Thus, how to schedule reworking in order to reduce the effect on waiting lots is a crucial issue for wafer manufacturing management.