• Journal of the Korean Vacuum Society
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• v.2 no.3
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• pp.335-338
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• 1993

텅스텐으로 만들어진 field emitter와 탄소로 만들어진 field emitter에서 생기는 step이나 spike 형태의 잡음에 대하여 비교 연구하였다. 그리고 dispenser 형태의 field emiter와 array 형태의 field emitter와 같은 새로운 형태의 field emitter를 설명하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.383-383
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• 2011

Generally, field emitters can be categorized into two types according to the emitter shape, one is a planar field emitter and the other is a point emitter. The planar field emitter is used for displays, flat lamps and signage boards. On the other hands, the point field emitter is expected to play a significant role in x-ray sources and electron beam sources. Such applications of the point field emitters, especially, need large emission current and high emission stability with a small electron beam size. A few reports announced point emitters made by carbon nanotubes (CNTs). However, they still have suffered from poor reproducibility and low emission current. Here, we demonstrated high performance CNT point emitters by attaching CNTs onto graphite rod. Graphite rod exhibited good electrical conductivity and chemical stability. In this method, the shape of the point emitter could be easily controlled by changing the length and diameter of the graphite rod. The CNT point emitter showed emission current over 1 mA at an applied electric field of 1.4 V/${\mu}m$. We consider that the stable emission performance is attributed to the stable contact between CNTs and graphite rod.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.937-939
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• 2007

Carbon nanotubes (CNTs) have used as an electron field emitter of the field emission display (FED) due to their characteristics of high-electron emission, rapid response and low power consumption. However, to commercialize the FED with CNT emitter, some fundamental problems regarding life time and emission efficiency have to be solved. In this study, we investigated the $TiO_2$ coated CNT as a field emitter. $TiO_2$ nanoparticles can coated on CNT surface by chemical solution method. $TiO_2$ nanoparticles had uniform size with the average size of about 2.4 nm to 3.1 nm. Field emission performance of CNT coated with $TiO_2$ nanoparticles was evaluated and discussed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.11
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• pp.1023-1028
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• 2003

The field emission characteristics are studied by simulation for carbon nanotube triode structures with a strip-shaped emitter and a gate hole aligned with it. Two structures, one with double-edge and the other with single edge are analyzed. They show good emission characteristics. Emissions of electrons are concentrated on the edges of emitter and the emitted current increases as the distance between emitter and gate decreases. For single-edged emitter, the emitted electrons form a narow strip-shaped beam which has a good directionality. These triode structures have advantages in that they can be easily fabricated and aligned for assembly.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.7
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• pp.1001-1006
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• 2012

This paper presents a carbon nanotube (CNT) triode-structure field emitter as an ion source in a micro time-of-flight mass spectrometer(TOF-MS). In the ion source by field emission, the electrons emitted from cathodes under an electric field accelerated to the anode and ionize gas molecules by impact before arriving the anode. The generated positive ions are to be accelerated to the ion collector. Whereas most of ions are drawn to the cathodes in diode field emitters, a grid in the triode field emitter prevents the ions from being drawn to the cathodes. The triode field emitter is fabricated by micromachining. The cathode is composed of six CNT cylinders. The total size of the fabricated device is $8.0{\times}7.3{\times}1.9mm^3$. The anode and the grid current of the fabricated CNT field emitter were measured for various anode and grid voltages. When the anode and the grid voltages are 1000 V and 990 V, respectively, the emission current passing through the ionization region is 8.6 ${\mu}A$, which is a sufficient emission current for ionization and mass spectrometry.

• JSTS:Journal of Semiconductor Technology and Science
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• v.2 no.2
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• pp.93-101
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• 2002

We have proposed and fabricated two lateral type field emission diodes, poly-Si emitter by utilizing the local oxidation of silicon (LOCOS) and GaN emitter using metal organic chemical vapor deposition (MOCVD) process. The fabricated poly-Si diode exhibited excellent electrical characteristics such as a very low turn-on voltage of 2 V and a high emission current of $300{\;}\bu\textrm{A}/tip$ at the anode-to-cathode voltage of 25 V. These superior field emission characteristics was speculated as a result of strong surface modification inducing a quasi-negative electron affinity and the increase of emitting sites due to local sharp protrusions by an appropriate activation treatment. In respect, two kinds of procedures were proposed for the fabrication of the lateral type GaN emitter: a selective etching method with electron cyclotron resonance-reactive ion etching (ECR-RIE) or a simple selective growth by utilizing $Si_3N_4$ film as a masking layer. The fabricated device using the ECR-RIE exhibited electrical characteristics such as a turn-on voltage of 35 V for $7\bu\textrm{m}$ gap and an emission current of~580 nA/l0tips at anode-to-cathode voltage of 100 V. These new field emission characteristics of GaN tips are believed to be due to a low electron affinity as well as the shorter inter-electrode distance. Compared to lateral type GaN field emission diode using ECR-RIE, re-grown GaN emitters shows sharper shape tips and shorter inter-electrode distance.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1277-1281
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• 2007

A Nano-tip as a cold field emitter for inducing a field emission current has manufactured in many ways. In the paper, the electrochemical etching method is used. Thus, in order to optimize the final shape as the field emitter, the reliable fabrication system for electrochemical etching was constructed. In addition, the effective parameters such as applied voltage, submerged length, meniscus height, electrolyte concentration and environmental condition(vibration, humidity, cut-off time) have investigated in detail. By controlling the parameters, reliable tungsten tip for field emitter was fabricated. And the fabricated tungsten tip was evaluated optically. Finally, the very sharp apex of the tungsten tip was observed with scanning electron microscope.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.150-150
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• 2010

Carbon nanotubes have drawn attention as one of the most promising emitter materials ever known not only due to their nanometer-scale radius of curvature at tip and extremely high aspect ratios but also due to their strong mechanical strength, excellent thermal conductivity, good chemical stability, etc. Some applications of CNTs as emitters, such as X-ray tubes and microwave amplifiers, require high current emission over a small emitter area. The field emission for high current density often damages CNT emitters by Joule heating, field evaporation, or electrostatic interaction. In order to endure the high current density emission, CNT emitters should be optimally fabricated in terms of material properties and morphological aspects: highly crystalline CNT materials, low gas emission during electron emission in vacuum, optimal emitter distribution density, optimal aspect ratio of emitters, uniform emitter height, strong emitter adhesion onto a substrate, etc. We attempted a novel approach to fabricate CNT emitters to meet some of requirements described above, including highly crystalline CNT materials, low gas emission, and strong emitter adhesion. In this study, CNT emitters were fabricated by filtrating an aqueous suspension of highly crystalline thin multiwalled CNTs (Hanwha Nanotech Inc.) through a metal mesh. The metal mesh served as a support and fixture frame of CNT emitters. When 5 ml of the CNT suspension was engaged in filtration through a 400 mesh, the CNT layers were formed to be as thick as the mesh at the mesh openings. The CNT emitter sample of $1{\times}1\;cm^2$ in size was characteristic of the turn-on electrical field of 2.7 V/${\mu}m$ and the current density of 14.5 mA at 5.8 V/${\mu}m$ without noticeable deterioration of emitters. This study seems to provide a novel fabrication route to simply produce small-size CNT emitters for high current emission with reliability.

• Applied Microscopy
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• v.46 no.3
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• pp.155-159
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• 2016

This paper analyses the relationship between the distribution of a dielectric layer on the apex of a metal field electron emitter and the distribution of electron emission. Emitters were prepared by coating a tungsten emitter with a layer of epoxylite resin. A high-resolution scanning electron microscope was used to monitor the emitter profile and measure the coating thickness. Field electron microscope studies of the emission current distribution from these composite emitters (Tungsten-Clark Electromedical Instruments Epoxylite resin [Tungsten/CEI-resin emitter]) have been carried out. Two forms of image have been observed: bright single-spot images, thought to be associated with a smooth substrate and a uniform dielectric layer; and multi-spot images, though to be associated with irregularity in the substrate or the dielectric layer.

• Journal of Electrical Engineering and Technology
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• v.3 no.1
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• pp.121-124
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• 2008

This paper presents the fabrication and field emission of carbon nanotube field emitters for a micro mass spectrometer. The carbon nanotube is an adequate material as a field emitter since it has good characteristics. We have successfully fabricated a diode field emitter and a triode field emitter. Each field emitter has been constructed using several micromachining processes and a thermal CVD process. In the case of the diode field emitter, to increase the electric field, the carbon nanotubes are selectively grown on the patterned nickel catalyst layer. The electron current of the diode field emitter is 73.2 ${\mu}A$ when the anode voltage is 1100V. That of the triode field emitter is 3.4 pA when the anode voltage is 1000V.