• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2008년도 제39회 하계학술대회
• /
• pp.1224-1225
• /
• 2008

The results of the experiment that was conducted on the electron emission property and the long-term stability of the emission current in various carbon nanotubes (CNTs)-based field emitters with a CNT/catalyst/buffer/W-tip configuration are presented herein. CNT-based field emitters were fabricated by varying the (TiN, Al/Ni/TiN) buffer layer and the (Ni, Co) catalyst material. This study aimed to elucidate how the buffer layers and catalyst materials affect the structural properties of CNTs and the long-term stability of CNT emitters. Raman spectroscopy, field emission SEM, and high-resolution TEM were used to analyze the crystalline structure, surface morphologies, and nanostructures of all the grown CNTs. X-ray photoelectron spectroscopy (XPS) was used to monitor the chemical bonds of all the buffer layers and catalysts. Electron emission measurement and a long-term (up to 40h) stability test were carried out using a compactly designed field emission measurement system.

• 한국진공학회지
• /
• 제17권6호
• /
• pp.566-575
• /
• 2008

촉매 화학기상증착법을 이용하여 합성된 이중층 탄소나노튜브를 가지고 전계전자 방출원을 제작하여 이들의 신뢰성 있는 전계전자 방출특성을 조사하였다. 합성된 탄소 필라멘트들은 TEM, TGA, 그리고 Raman 분석을 통하여 결함이 없고 순도가 높은 이중층 탄소나노튜브가 합성이 되었음을 확인하였다. 이들 이중층 탄소나노튜브 전계전자 방출원은 이전극 구조에서 낮은 턴-온 전계와 높은 전류밀도의 전계전자 방출 특성을 보여주었고, 균질한 전계방출 패턴과 좋은 전계방출 안정성을 나타내었다.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 1996년도 재료학회 춘계학술발표회
• /
• pp.85-85
• /
• 1996

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 1994년도 제6회 학술발표회 논문개요집
• /
• pp.19-21
• /
• 1994

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
• /
• pp.171.1-171.1
• /
• 2015

Carbon nanotube emitters is very promising electron emitter for electron beam applications. We introduced the carbon nanotube electron beam (C-beam) exposure technic using triode structure. As a source, the electron beam emit from CNT emitters placed at the cathode by high electric field. Through the gate mesh, with high accelerating energy, the electron can be extracted easily and impact at the anode plate. For thin film modification, after the C-beam exposure on the amorphous silicon thin film, we found phase changes and it showed a high crystallinity from the Raman measurement. We expect that this crystallized film will be a good candidate as a new active layer of TFT.

• 디지털산업정보학회논문지
• /
• 제5권1호
• /
• pp.83-88
• /
• 2009

This paper consider the problem of direction of arrival(DOA) estimation in the presence of multipath propagation. The sensor elements are assumed to be linear and uniformly spaced. Numerous authors have advocated the use of a beamforming preprocessor to facilitate application of high resolution direction finding algorithms The benefits cited include reduced computation, improved performance in environments that include spatially colored noise, and enhanced resolution. Performance benefits typically have been demonstrated via specific example. The purpose of this paper is to provide an analysis of a beamspace version of the MUSIC algorithm applicable to two closely spaced emitters in diverse scenarios. Specifically, the analysis is applicable to uncorrelated far field emitters of any relative power level, confined to a known plane, and observed by an arbitrary array of directional antenna. In this paper, we researched about optimize beam forming to smart antenna system. The covariance matrix obtained using fourth order cumulant function. Simulations illustrate the performance of the techniques.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2011년도 제42회 하계학술대회
• /
• pp.1410-1411
• /
• 2011

Tip-type carbon nanotube(CNT) based electron emitters were fabricated by forming a hafnium(Hf) interlayer between the CNT and the substrate. The CNTs were deposited by using the electrophoretic deposition method and thermally treated. No significant change in the microscopic structure of the CNTs, such as the ratio of length to diameter, was observed after the deposition of Hf interlayer and thermal treatment. As compared with the CNT emitter without the Hf-interlayer and thermal treatment, the CNT emitter with the Hf-interlayer and thermal treatment showed noticeably improved electron-emission properties due to the enhanced adhesion.

• Transactions on Electrical and Electronic Materials
• /
• 제17권5호
• /
• pp.306-309
• /
• 2016

The Cs₃Sb photocathode was formed by non-vacuum process technology. An in-situ vacuum device was fabricated successively with flat cesium antimonide photocathode emitters fabricated in a process chamber. The electrical properties of the device were characterized. Electron emission from the devices was induced by photoemitted electrons, which were accelerated by an anode electric field that was shielded from the photoemitter surface. The electrical characteristics of the devices were investigated by measuring the anode current as a function of device operation times with respect to applied anode voltages. Planar blue LED light with a 450 nm wavelength was used as an excitation source. The results showed that the cesium antimonide photocathode emitter has the potential of long lifetime with stable electron emission characteristics in panel devices. These features demonstrate that the cesium antimony photocathodes produced by non-vacuum processing technology is suitable for flat cathodes in panel device applications.

• Journal of Electrical Engineering and Technology
• /
• 제3권1호
• /
• pp.121-124
• /
• 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.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
• /
• pp.366-368
• /
• 2006

Electronic warfare Support(ES) system measures pulse characteristics for received RF signals that received from all directions. ES system discriminates the pulse trains that have a rule, correlationship, continuance from collected data and analyze the characteristics of the data, and identify the emitters by comparison with emitter identification data(EID). Because pulse density is very high and various signal source exists at modem signal environments, high-speed and accurate signal analysis is needed for realtime countermeasure to emitters. Grouping alleviates the load of signal analysis process and supports reliable analysis. In this paper, we suggest an adaptive clustering scheme regarding signal patterns.