• 한국전기전자재료학회논문지
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• 제15권8호
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• pp.713-719
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• 2002

In this study, the vertically well-aligned CNTs were synthesized by DC bias-assisted inductively coupled plasma hot-filament chemical vapor deposition (ICPHFCVD) using radio-frequence plasma of high density and that CNTs were vertically grown on Ni(300 )/Cr(200 )-deposited glass substrates at 58$0^{\circ}C$. This system(ICPHFCVD) added to tungsten filament in order to get thermal decompound and DC bias in order to vertically grow to general Inductively Coupled Plasma CVD. The grown CNTs by ICPHFCVD were developed to higher graphitization and fewer field emission properties than those by general ICPCVD. In this system, DC bias was effect of vortical alignment to growing CNTs. The measured turn-on fields of field emission property by general ICPCVD and DC bias-assisted ICPHFCVD were 5 V/${\mu}{\textrm}{m}$ and 3 V/${\mu}{\textrm}{m}$, respectively.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.159-159
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• 2016

Vertically-aligned carbon nanotubes (VCNT) have attracted much attention due to their unique structural, mechanical and electronic properties, and possess many advantages for a wide range of multifunctional applications such as field emission displays, heat dissipation and potential energy conversion devices. Surface modification of the VCNT plays a fundamental role to meet specific demands for the applications and control their surface property. Recent studies have been focused on the improvement of the electron emission property and the structural modification of CNTs to enable the mass fabrication, since the VCNT considered as an ideal candidate for various field emission applications such as lamps and flat panel display devices, X-ray tubes, vacuum gauges, and microwave amplifiers. Here, we investigate the effect of surface morphology of the VCNT by water vapor exposure and coating materials on field emission property. VCNT with various height were prepared by thermal chemical vapor deposition: short-length around $200{\mu}m$, medium-length around $500{\mu}m$, and long-length around 1 mm. The surface morphology is modified by water vapor exposure by adjusting exposure time and temperature with ranges from 2 to 10 min and from 60 to 120oC, respectively. Thin films of SiO2 and W are coated on the structure-modified VCNT to confirm the effect of coated materials on field emission properties. As a result, the surface morphology of VCNT dramatically changes with increasing temperature and exposure time. Especially, the shorter VCNT change their surface morphology most rapidly. The difference of field emission property depending on the coating materials is discussed from the point of work function and field concentration factor based on Fowler-Nordheim tunneling.

• 한국진공학회지
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• 제9권2호
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• pp.110-115
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• 2000

열-필라멘트 CVD 장치를 이용하여 다이아몬드 박막의 증착 조건을 최적화시켰다. $B_4C $ 고체 펠렛을 사용하여 보론두핑된 다이아몬드 박막을 제조하여 그 질적 특성을 알아보고, 전류전압 특성과 전계 방출 측정을 통해 박막의 전계방출소자(field emission display (FED)로의 특성을 조사하였다. 보론 도핑의 양이 증가함에 따라 다이아몬드 결정의 평균 입자 크기가 조금씩 감소하지만 다이아몬드의 질은 소량 도핑인 경우에 크게 바뀌지 않았다. Al/Diamond/p-Si 소자의 전류전압 특성을 조사한 결과 도핑된 다이아몬드 박막의 전류는 도핑되지 않은 박막의 전류에 비해 $10^4$~$10^5$배 정도 증가하였다. 전계방출 특성을 조사한 결과 보론-도핑이 증가함에 따라 점차 낮은 전기장에서 전자를 방출하며, 또한 높은 방출 전류를 나타냈다. 전자가 방출되기 시작하는 onset-field는 펠렛의 수가 2개일 때 15.5 V/$\mu\textrm{m}$, 3개일 때 13.6 V/$\mu\textrm{m}$, 4개일 때는 11.1 V/$\mu\textrm{m}$. 체계적으로 감소하였다. 도핑의 강도가 세어짐에 따라 Fowler-Nordheim 그래프의 기울기는 감소하는 경향을 보였으며, 이로서 보론 도핑으로 인해 유효 장벽 에너지가 감소되어 전자 방출 특성이 향상됨을 알 수 있었다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 추계학술발표대회
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• pp.18.1-18.1
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• 2011

Some applications of carbon nanotubes (CNTs) as field emitters, such as x-ray tubes and microwave amplifiers, require high current emission from a small emitter area. To emit the high current density, CNT emitters should be optimally fabricated in terms of material properties and morphological aspects including high crystallinity, aspect ratio, distribution density, height uniformity, adhesion on a substrate, low outgassing rate during electron emission in vacuum, etc. In particular, adhesion of emitters on the substrate is one of the most important parameters to be secured for high current field emission from CNTs. So, we attempted a novel approach to improve the adhesion of CNT emitters by incorporating metal oxide layers between CNT emitters. In our previous study, CNT emitters were fabricated on a metal mesh by filtrating the aqueous suspensions containing both highly crystalline thin multiwalled CNTs and thick entangled multiwalled CNTs. However, the adhesion of CNT film was not enough to produce a high emission current for an extended period of time even after adopting the metal mesh as a fixing substrate of the CNT film. While a high current was emitted, some part of the film was shown to delaminate. In order to strengthen the CNT networks, cobalt-nickel oxides were incorporated into the film. After coating the oxide layer, the CNT tips seemed to be more strongly adhered on the CNT bush. Without the oxide layer, the field emission voltage-current curve moved fast to a high voltage side as increasing the number of voltage sweeps. With the cobalt-nickel oxide incorporated, however, the curve does not move after the second voltage sweep. Such improvement of emission properties seemed to be attributed to stronger adhesion of the CNT film which was imparted by the cobalt-nickel oxide layer between CNT networks. Observed after field emission for an extended period of time, the CNT film with the oxide layer showed less damage on the surface caused by high current emission.

• 한국재료학회지
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• 제17권3호
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• pp.173-178
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• 2007

Carbon nanotube cathodes(CNT cathodes) with a trench structure similar to gated structure of triode-type cathode were fabricated by a screen printing method using multi-walled carbon nanotubes. The effects of surface treatments on CNT cathodes were investigated for high efficiency field emission displays(FEDs). A liquid method easily removed the organic residue and protruded the CNTs. Field emission properties were measured by using a diode-type mode. The liquid method produced a turn-on field of $1.4V/{\mu}m$. The emission current density was measured about $3.1mA/cm^{2}$ at the electric field of $3V/{\mu}m$. The liquid method showed a high potential applicable to the surface treatment for triode-type FEDs.

• Bulletin of the Korean Chemical Society
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• 제34권6호
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• pp.1779-1782
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• 2013

N-type ZnO nanorods were grown on p-type porous silicon using a chemical bath deposition (CBD) method (p-n diode). The structure and geometry of the device were examined by field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) while the optoelectronic properties were investigated by UV/Vis absorption spectrometry as well as photoluminescence and electroluminescence measurements. The field emission (FE) properties of the device were also measured and its turn-on field and current at 6 $V/{\mu}m$ were determined. In principle, the growth of ZnO nanorods on porous siicon for optoelectronic applications is possible.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.696-699
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• 2004

Of the emissive display technologies, field emission displays using pasted carbon nanotubes offer several advantages over other competing cathode materials such as low driving voltage, possible large-area and low-cost processes. In this study, formulation of carbon nanotube paste and its electron field emission properties are characterized. Also the effects of additive powders and surface morphology on electron emission are reported.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.692-695
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• 2004

Fabrication of photosensitive carbon nanotubes paste and its post-treatment has been developed for high resolution with good electron emission uniformity. We report novel post-treatment techniques including rubber-rolling and multiple field emission cycling from which we could improve the field emission properties of printed carbon nanotubes. These techniques would be easily applicable to large area field emission display using paste of carbon nanotubes

• 한국진공학회지
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• 제17권6호
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• pp.566-575
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• 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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.51-51
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• 2008

Carbon nanotubes (CNTs) have long been reported as an ideal material due to their excellent electrical conductivity and chemical and mechanical stability as well as their high aspect ratios for field emission devices. CNT emitters made by screen printing the organic binder-based CNT paste may act as a source to release gases inside a vacuum panel. These residual gases may cause a catastrophic damage by electrical arcing or ion bombardment to the vacuum microelectronic devices and may change their physical or electrical properties by adsorbing on the CNT emitter surface. In this study, we analyzed the composition of residual gases inside the vacuum-sealed panel by residual gas analyzer (RGA), investigating the effects of individual gases of different kinds at several pressures on the field emission characteristics of CNT emitters. The residual gases included $H_2$, CO, $CO_2$, $N_2$, $CH_4$, $H_2O$, $C_2H_6$, and Ar. Effect of residual gases on the field emission was studied by observing the variation of the pulse voltages with the duty ratio of3.3% to keep the constant emission current of $28{\mu}A$. Each gas species was introduced to a vacuum chamber up to three different pressures ($5\times10^{-7}$, $5\times10^{-6}$, and $5\times10^{-5}$ torr) each for 1 h while electron emission was continued. The three different pressure regions were separated by keeping a high vacuum of $\sim10^{-8}$ torr for a 1 h. The emission was terminated 6 h after the third gas exposure was completed. Field emission characteristics under residual gases will be discussed in terms of their adsorption and desorption on the surface of CNTs and the resultant change of work function.