Browsing by Author "Hong, WK"

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Chimney-shaped and plateau-shaped gate electrode field emission arrays
(1998)
Tarntair, FG
;
Wang, CC
;
Hong, WK
;
Huang, HK
;
Cheng, HC
A triode structure of chimney-shaped field emitter arrays is proposed in this article. This triode structure includes the chimney-shaped emitter, thermal oxidation dioxide, and the plateau-shaped singlecrystalline silicon gate electrode. For the application of the matrix-addressable and large area flat panel display, the uniform structure of the emitters and the yield become critical manufacturing issues when attempting to control nano-meter size features. The uniformity and yield of the chimney-shaped emitters are very well controlled. The nano-sized gate-to-emitter separations can be created by the changing thickness of the insulator. The uniformity of the insulator and emitter material can be controlled within 3% which can be obtained by most large area thin film deposition tools, not by photolithography.
Chimney-shaped and plateau-shaped gate electrode field emission arrays
(1998)
Tarntair, FG
;
Wang, CC
;
Hong, WK
;
Huang, HK
;
Cheng, HC
A triode structure of chimney-shaped field emitter arrays is proposed in this article. This triode structure includes the chimney-shaped emitter, thermal oxidation dioxide, and the plateau-shaped singlecrystalline silicon gate electrode. For the application of the matrix-addressable and large area flat panel display, the uniform structure of the emitters and the yield become critical manufacturing issues when attempting to control nano-meter size features. The uniformity and yield of the chimney-shaped emitters are very well controlled. The nano-sized gate-to-emitter separations can be created by the changing thickness of the insulator. The uniformity of the insulator and emitter material can be controlled within 3% which can be obtained by most large area thin film deposition tools, not by photolithography.
Chimney-shaped and plateau-shaped gate electrode field emission arrays
(1998-01-01)
Tarntair, FG
;
Wang, CC
;
Hong, WK
;
Huang, HK
;
Cheng, HC
A triode structure of chimney-shaped field emitter arrays is proposed in this article. This triode structure includes the chimney-shaped emitter, thermal oxidation dioxide, and the plateau-shaped singlecrystalline silicon gate electrode. For the application of the matrix-addressable and large area flat panel display, the uniform structure of the emitters and the yield become critical manufacturing issues when attempting to control nano-meter size features. The uniformity and yield of the chimney-shaped emitters are very well controlled. The nano-sized gate-to-emitter separations can be created by the changing thickness of the insulator. The uniformity of the insulator and emitter material can be controlled within 3% which can be obtained by most large area thin film deposition tools, not by photolithography.
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 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.
Fabrication and characterization of various carbon-clad silicon microtips with ultra-small tip radii
(2000-02-01)
Tarntair, FG
;
Hong, WK
;
Ku, TK
;
She, NJ
;
Chen, CF
Various types of ultra sharp Si microtips and multitips with carbon-clading films were fabricated by microwave plasma chemical vapor deposition (MPCVD). The radii of these Si tips prepared by bias assisted carburization (BAC) can he reduced below 300 Angstrom under a low deposition temperature (<550 degrees C). Field emission characterization was performed in a high vacuum environment. With an applied anode voltage of 1100 V, emission currents of 169 mu A, 198 mu A, and 385 mu A can be achieved from an array of 50 x 50 BAG-clad Si monotips, Si multitips via high bias, and Si multitips via the Ar presputtering technique, respectively. Both the auger electron spectroscopy (AES) and X-ray photo-electron spectroscopy (XPS) studies of the C l s peak suggest that the BAC-cladding is more likely to be a carbon-rich SiC layer or a SiC layer mixed with a small amount of diamond nuclei. This BAC-carbon can be used as an effective nucleation layer for further diamond nuclei. Due to the low field emission, low temperature, and large area growth capability, the sharp BAC-clad Si multitip field emitter arrays are attractive Tor flat panel display applications.
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.
Field emission from quasi-aligned SiCN nanorods
(2000-05-01)
Tarntair, FG
;
Wen, CY
;
Chen, LC
;
Wu, JJ
;
Chen, KH
We report on the preparation and field emission properties of quasi-aligned silicon carbon nitride (SiCN) nanorods. The SiCN nanorods are formed by using a two-stage growth method wherein the first stage involves formation of a buffer layer containing high density of nanocrystals by electron cyclotron resonance plasma enhanced chemical vapor deposition and the second stage involves using microwave plasma enhanced chemical vapor deposition for high growth rate along a preferred orientation. It should be noted that growth of the SiCN nanorods is self-mediated without the addition of any metal catalyst. Scanning electron microscopy shows that the SiCN nanorods are six-side-rod-shaped single crystals of about 1-1.5 mu m in length and about 20-50 nm in diameter. Energy dispersive x-ray spectrometry shows that the nanorod contains about 26 at. % of Si, 50 at. % of C, and 24 at. % of N. Characteristic current-voltage measurements indicate a low turn-on field of 10 V/mu m. Field emission current density in excess of 4.5 mA/cm(2) has been observed at 36.7 V/mu m. Moreover, SiCN nanorods exhibited rather stable emission current under constant applied voltage. (C) 2000 American Institute of Physics. [S0003-6951(00)01117-7].
Field-emission properties of aligned carbon nanotubes
(2000-09-15)
Hong, WK
;
Shih, HC
;
Tsai, SH
;
Shu, CT
;
Tarntair, FG
Dense, well-separated, and aligned carbon nanotubes have been prepared via bias-enhanced microwave plasma chemical vapor deposition. The turn-on fields defined at the emission current density of 10 mu A/cm(2) are about 3.35 V/mu m, 2.54 V/mu m, and 3.54V/mu m, for the immersion times in PdCl2 of 1 min, 20 min, and 40 min,respectively. The corresponding emission current densities are about 0.97 mA/cm(2), 4.5 mA/cm(2), and 0.44 mA/cm(2) at the electric field of 5 V/mu m. The higher emission current obtained from the aligned carbon nanotubes for the immersion time of 20 min is ascribed to the denser and sharper nanotubes formed in this condition.
High current density field emission from arrays of carbon nanotubes and diamond-clad Si tips
(2000-05-01)
Tarntair, FG
;
Chen, LC
;
Wei, SL
;
Hong, WK
;
Chen, KH
Arrays of carbon nanotubes (CNT) and diamond-clad Si tips were grown by microwave plasma-enhanced chemical vapor deposition. The former ones were grown directly on prepatterned cobalt-coated silicon substrate, while the latter ones were grown on Si-tip arrays. Each array contains 50 x 50 emitting cells and each individual cell is 3 mu m square. A maximum effective emission current density of about 17 A/cm(2) (at a macroscopic field of 17.5 V/mu m) has been demonstrated, while a macroscopic emission current density of 10 mA/cm(2) with operating fields around 10 V/mu m can be routinely achieved from an an ay of CNT emitters. In contrast, operating fields above 20 V/mu m were needed to draw a comparable emission current density from all of the diamond-clad Si tips arrays. Emission stability test performed at 40 mA/cm(2) for CNT arrays also showed little sign of degradation. Due to the high efficiency of electron emission, simple sample process, and large area growth capability, field emitter arrays based on CNT are attractive for flat panel display applications. (C) 2000 American Vacuum Society. [S0734-211X(00)08003-3].
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.