• 한국진공학회지
• /
• 제15권5호
• /
• pp.541-546
• /
• 2006

본 연구에서는 박막형 $ZnGa_2O_4:Mn$ 산화물 형광체의 음극선루미느센스 특성과 구조적 성질에 대하여 field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), photoluminescence (PL), 그리고 cathodoluminescence (CL) 방법을 이용하여 조사하였다. $ZnGa_2O_4:Mn$ 형광체 타겟으로부터 $Mn^{2+}$ 이온의 $^4T_1{\rightarrow}^6A_1$ 전이에 의한 506nm 파장에서의 PL emission 스펙트럼이 관찰되었다. 색좌표는 x = 0.09, y = 0.67 이었다. $ZnGa_2O_4:Mn$ 박막의 여기 스펙트럼은 $Mn^{2+}$ 이온 흡수에 의한 294 nm의 피크 파장을 나타내었다. 낮은 압력에서 증착한 $ZnGa_2O_4:Mn$ 형광체 박막은 고밀도의 치밀한 단면구조를 보였고, 높은 세기의 음극선루미느센스가 505 nm 피크 파장에서 나타났다. 표면 거칠기가 음극선루미느센스의 세기에 미치는 영향은 관찰되지 않았다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2010년도 하계학술대회 논문집
• /
• pp.150-150
• /
• 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.

• 한국토양비료학회지
• /
• 제46권6호
• /
• pp.463-468
• /
• 2013

The level of nitrous oxide ($N_2O$), a long-lived greenhouse gas, in atmosphere has increased mainly due to anthropogenic source, especially application of nitrogen fertilizers. Quantifying $N_2O$ emission from agricultural field is essential to develop national inventories of greenhouse gases (GHGs) emission. The objective of the study was to develop emission factor to estimate direct $N_2O$ emission from agricultural field in Gangwon-do, Korea by measuring $N_2O$ emissions from potato (Solanum tuberosum), red pepper (Capsicum annum L.), and Chinese cabbage (Brassica campestris L.) cultivation lands from 2009 to 2012. Accumulated $N_2O$ emission was $1.48{\pm}0.25kg$ $N_2O-N\;ha^{-1}$ for red pepper, $1.27{\pm}0.27kg$ $N_2O-N\;ha^{-1}$ for potato, $1.49{\pm}0.06kg$ $N_2O-N\;ha^{-1}$ for Chinese cabbage cultivated in spring, and $1.14{\pm}0.22kg$ $N_2O-N\;ha^{-1}$ for fall Chinese cabbage. Emission factor of $N_2O$ calculated from accumulated $N_2O$ emission, nitrogen fertilization rate, and background $N_2O$ emission was $0.0051{\pm}0.0016kg$ $N_2O-N\;ha^{-1}$ N for cropland in Gangwon province. More extensive study is deserved to be conducted to develop $N_2O$ emission factor for upland crops in Korea through examining the emission factors from various regions and crops because $N_2O$ emission is influenced by many factors including climate characteristics, soil properties, and agricultural practices.

• KIEE International Transactions on Electrophysics and Applications
• /
• 제11C권4호
• /
• pp.138-141
• /
• 2001

The fluorescence emission spectrum of Cr$^{3+}$ doped BeAl$_{6}$ O$_{10}$ crystals at 300 K contains a broad band, three R-like lines and another emission lines. It has been identified by a lifetime resolution spectroscopic technique that there are three kinds of single-Cr$^{3+}$ centers, Cr(I), Cr(II), Cr(III), in this crystal. Cr(I) and Cr(II) are high-crystal field centers responsible for the three main "R-lines", and Cr(III) is a low-crystal field center responsible for the main broad band emission. The structures of these luminescent centers are reported.ted.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 하계학술대회 논문집 D
• /
• pp.1511-1513
• /
• 1999

In order to investigate the properties of diamond-like carbon(DLC) thin films depending on the deposition parameters, DLC thin films were systematically fabricated by pulsed laser deposition (PLD), DLC thin films have been shown advantageous field emission properties due to a negative electron affinity (NEA) and a low work function. At the atomic level. DLC is referred to the group of carbon materials with strong chemical bonding composition of $sp^2$ and $sp^3$ arrangements of atoms incorporated with an amorphous structure. The experiment was performed at substrate temperature in the range of room temperature to $600^{\circ}C$. The laser energy densiy was used to be in the range of $6J/cm^2$ to $20J/cm^2$, SEM, Raman, PL, XPS and field emission characteristics were used to investigate the DLC thin films.

• 한국세라믹학회지
• /
• 제41권12호
• /
• pp.880-883
• /
• 2004

Carbon nanofibers could be selectively formed at the groove area of the MgO substrate using microwave plasma-enhanced chemical vapor deposition system. Iridium metal was used as a catalyst layer for the formation of the carbon nanofibers. The growth direction of the carbon nanofibers was vertical to the substrate surface. The selectively grown iridium-catalyzed carbon nanofibers show around $1.8V/{\mu}m$ turn-on voltage and $1.0\;mA/cm^2$ field emission current density at $2.65\;V/{\mu}m$ in the field emission measurement.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 추계학술대회 논문집 전기물성,응용부문
• /
• pp.293-296
• /
• 2003

We report on the fabrication and field emission of carbon nanotube field emitters for mass spectrometer. Due to its high aspect ratio and mechanical strength, we use vertically aligned multi-wall carbon nanotubes prepared by thermal chemical vapour deposition as cathodes, Electrons emitted from a CNT are to ionize some sample molecules. We have successfully attained patterned carbon nanotubes grown on two-dimensional 0.7 mm by 0.7 mm Ni square blocks on Si. The emission characteristics show that the field emission initiates at 200 V.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권2호
• /
• pp.1545-1546
• /
• 2007

Zinc gallate-based RGB phosphors and vertically aligned carbon nanotube emitters are prepared for flat field-emission lamp. The blend phosphors of blue $ZnGa_2O_4$, green $ZnGa_2O_4:Mn^{2+}$ and red $ZnGa_2O_4:Cr^{3+}$ are coated on the front glass, and the carbon nanotubes are chemically bonded on the rear ITO glass as a cathode.

• 한국전기전자재료학회논문지
• /
• 제14권10호
• /
• pp.850-854
• /
• 2001

In this study, carbon nanotubes was vertically grown pm Ni/Cr-deposited glass substrates by Inductively Coupled Plasma Chemical Vapor Deposition. Using Radio-Frequence(RF) plasma below temperature of 600$^{\circ}C$. The grown CNTs shows field emission properties and high quality materials. Turn-on fields and current density showed 5V/${\mu}$m and 1.06${\times}$10$\^$-6/ A/$\textrm{cm}^2$, respectively.

• Carbon letters
• /
• 제12권4호
• /
• pp.218-222
• /
• 2011

Well-aligned multi-walled carbon nanotubes (MWCNTs) were successfully synthesized by catalytic chemical vapor deposition using a hydrogen sulfide ($H_2S$) additive onto Al/Fe thin film deposited on Si wafers. Transmission electron microscopy images indicated that the as-grown carbon products were thin MWCNTs with small outer diameters of less than 10 nm. $H_2S$ plays a key role in synthesizing thin MWCNTs with a large inside hollow core. The well-aligned thin MWCNTs showed a low turn-on voltage of about 1.1 V/${\mu}m$ at a current density of 0.1 ${\mu}A/cm^2$ and a high emission current of about 1.0 mA/$cm^2$ at a bias field of 2.3 V/${\mu}m$. We suggest a possible growth mechanism for the well-aligned thin MWCNTs with a large inside hollow core.