• Transactions on Electrical and Electronic Materials
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• 제11권6호
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• pp.279-284
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• 2010

This study has been carried out to determine the optimal process conditions of $AZO:H_2$ thin films for the maximization of the transmittance of a blue GaN light-emitting diode (LED) with a wavelength of 470 nm. The Al-doped zinc oxide $(AZO):H_2$ thin films were deposited on a sapphire substrate by radio-frequency magnetron sputtering system with varying substrate temperatures, working pressures and annealing temperatures temperature, working pressure and annealing imposed on a AZO (2wt% $Al_2O_3$) ceramic target. The effect of these variables was investigated in order to improve the light extraction efficiency of the LED. As a result, the (002)-oriented peak was found in all the $AZO:H_2$ thin films. The lowest resistivity and the best transmittance at a wavelength of 470 nm was found to be $4.774\;{\times}\;10^{-4}\;{\Omega}cm$ and 92% at a substrate temperature of $500^{\circ}C$, working pressure of 7 mTorr and annealing temperature of $400^{\circ}C$. The transmittance of the $AZO:H_2$ thin film for the Blue GaN LED was improved by approximately 13% relative to that of a ITO thin film (T = 79%).

• Transactions on Electrical and Electronic Materials
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• 제8권3호
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• pp.110-114
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• 2007

Dependence of the thermal stability of nickel silicide on the film stress of inter layer dielectric (ILD) layer has been investigated in this study and silicon nitride $(Si_3N_4)$ layer is used as an ILD layer. Nickel silicide was formed with a one-step rapid thermal process at $500^{\circ}C$ for 30 sec. $2000{\AA}$ thick $Si_3N_4$ layer was deposited using plasma enhanced chemical vapor deposition after the formation of Ni silicide and its stress was split from compressive stress to tensile stress by controlling the power of power sources. Stress level of each stress type was also split for thorough analysis. It is found that the thermal stability of nickel silicide strongly depends on the stress type as well as the stress level induced by the $Si_3N_4$ layer. In the case of high compressive stress, silicide agglomeration and its phase transformation from the low-resistivity nickel mono-silicide to the high-resistivity nickel di-silicide are retarded, and hence the thermal stability is obviously improved a lot. However, in the case of high tensile stress, the thermal stability shows the worst case among the stressed cases.

• 한국수산과학회지
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• 제40권3호
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• pp.160-166
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• 2007

The coarse deposit with a lower mud content adjacent to the shelf of the southern East Sea is probably a "relict" sediment deposited in response to a lower stand of sea level during the Pleistocene. The sediment that developed on the slope and in the deep sea was river-borne primarily and was secondarily reworked or redistributed by the Tsushima Warm Current from the East China Sea. The clay mineralogy of the area suggests various sources of fine-grained sediment from adjacent rivers, the Korea Strait, volcanic material from Ulleung Island, and the Japan coast. Massive sand, bioturbated mud, homogeneous mud, and laminated mud were the dominant facies found in the core sediments from the study area. The massive sand was mainly volcanic ash from an eruption on Ulleung Island (9300 yr BP) and consisted of colorless pumiceous glass and a black scoriaceous type. The sedimentation rates on the slope, based on the Ulleung-Oki ash layer, were about 10cm/ky higher than in the basin. Other than the coarse-grain sediment, the mean size of the fine sediment dominating the bioturbated and homogeneous muds in the basin and the laminated mud on the slope was 6-10 phi. This indicates a difference in the major sedimentary process: hemipelagic sedimentation in the Ulleung Basin and mass flow deposition, such as turbidite, on the slope of the southern East Sea.

• 전자공학회논문지D
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• 제34D권12호
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• pp.89-100
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• 1997

This paper investigated a new type of low voltage threshold switch (LVTS). As distinguished from the many other types of electronic threshold switches, the LvTS is ; voltage controlled, occurs at low voltages ($V_{2}$ $O_{5}$lV devices. The average low threshold voltage < $V_{LVT}$>=218 mV (standard deviation =24mV~kT/q, where T=300K), and was independent of the device area (x100) and amorphous oxide occurred in an ~22.angs. thick interphase of the V/amorphous- $V_{2}$ $O_{5}$ contacts. At $V_{LVT}$ there was a transition from an initially low conductance (OFF) state into a succession of quantized states of higher conductance (ON). The OFF state was spatically homogeneous and dominated by tunneling into the interphase. The ON state conductances were consistent with the quantized conductances of ballistic transport through a one dimensional, quantum point contact. The temeprature dependence of $V_{LVT}$, and fit of the material parameters (dielectric function, barrier energy, conductivity) to the data, showed that transport in the OFF and ON states occurred in an interphase with the characteristics of, respectively, semiconducting and metallic V $O_{2}$. The experimental results suggest that the LVTS is likely to be observed in interphases produced by a critical event associated with an inelastic transfer of energy.rgy.y.rgy.

• 한국자기학회지
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• 제8권1호
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• pp.27-33
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• 1998

스파터링법으로 Si(001) 기판 위에 증착된 Fe(1000 $\AA$)/Al2O3(t$\AA$)/Co(1000$\AA$) 자기 삼층 접합들의 터널링 자기저항 성질을 연구하였다. 두께 t=50~200$\AA$의 Al2O3층을 반응성 rf 스파터링법으로 바닥 자성층위에 직접 증착하였다. 비교응 위해, Pt/Al2O3/Pt 터널링 접합을 제조하여 상온에서 전류.전압(I.V)특성을 측정한 결과, 확인한 비선형 nonmhic 거동을 나타내었다. 이로부터 반응성 스파터링된 Al2O3가 상온에서도 phnhole이 없는 휼룔한 절연 터널링 장벽을 형성함을 확인할 수 있었다. Fe/Al2O3/Co 자기 터널링 접합즐은 Pt/Al2O3/Pt 접합들에 비해 상당한 접합저항의 열화를 보였으며, 상온에서 대략 0.1%의 터널링 자기저항비를 나타내었다. Fe를 꼭대기 전극으로 하는 전극으로 하는 접합들에 비해, Co을 꼭대기 전극으로 하는 대부분의 자기 터널링 접합들이 보다 안정된 I.V 및 터널링 자기저항 특성을 보였다. 이러한 실험결과들을 자기 터널링 접합들의 계면구조와 관련지어,Pt/Al2O3/Ptwjq합과 비교하여 논의하였다.

• 센서학회지
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• 제13권2호
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• pp.96-100
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• 2004

Optical fiber sensors have been used to detect small amounts of chemical species. In this work, a new thin polymer-clad fiber sensor is developed. Polyaniline is chemically synthesized and thin clad layers of the polymer are easily deposited on optical fiber by dip-coating technique. The optical property of polyaniline as a sensing material is analyzed by UV-Vis-NIR. The light source is stabilized He-Ne laser at 635 nm wavelength with 1 mW power. The light power transmitted through the optical fiber is measured with a spectrophotometer. By selecting a fixed incident angle, variation of transmitted light intensity through the optical fiber can be detected as gas molecules absorbed in the polyaniline clad layer. Among the various gases, the fabricated optical fiber sensor shows good sensitivity to $NH_{3}$ gas. The optical fiber sensors was shown more improved properties than polymer based sensors which measure conductivity changes.

• Progress in Superconductivity
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• 제6권2호
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• pp.133-137
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• 2005

We fabricated the Au/Ni template for YBCO coated conductors and evaluated texture formation and the microstructural evolution. The cube textured Ni substrate was fabricated by rolling and recrystallization annealing, and subsequently Au layer formed on the substrate by electroless-plating method. The texture was evaluated by pole-figure with x-ray goniometer with orientation distribution function (ODF) analysis. The surface roughness and grain boundary morphology of template were characterized by atomic force microscopy (AFM) We observed that Au layer deposited epitaxially on Ni substrate and formed a strong cube texture when plating time was optimized. The full-width at half-maximum (FWHM) was $8.4^{\circ}$ for out-of-plane and $9.98^{\circ}$ for in-plane texture for plating time of 30 min. Microstructural observation showed that the Au layer was homogeneous and dense without formation of crack/microcrack. In addition, we observed that root-mean-square (RMS) and depth of grain boundary were 14.6 nm and 160 $\AA$ for the Au layer, respectively, while those were 27.0 nm and 800 $\AA$ for the Ni substrate, indicating that the electoless-plated Au layer had relatively smooth surface and effectively mollified grain groove.

• 한국세라믹학회지
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• 제42권2호
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• pp.94-98
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• 2005

[ $RuO_2$ ]는 DRAM과 FRAM소자에서 고유전 capacitors의 저전극물질로서 폭넓게 연구되고 있다. 본 연구에서는 XRD, SEM, AFM 분석 등을 통하여 금속유기 화학 증착법(MOCVD)으로 $RuO_2$ 증착시 핵생성에 영향을 미치는 수소, 산소, 아르곤 ECR플라즈마 전처리 효과를 조사하였으며, 아르곤 ECR플라즈마 전처리의 경우 가장 높은 핵생성 밀도를 나타내었다. ECR 플라즈마 전처리를 통한 $RuO_2$의 핵생성 향상 메카니즘은 아르곤이나 수소 ECR 플라즈마는 TiN막 표면의 질소나 산소원자를 제거하고 따라서 TiN막 표면은 Ti-rich TiN으로 바뀌게 되는 것이다.

• 한국세라믹학회지
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• 제48권6호
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• pp.621-624
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• 2011

In order to deposit a homogeneous and uniform ${\beta}$-SiC films by chemical vapor deposition, we constructed the phase-diagram of ${\beta}$-SiC over graphite and silicon via computational thermodynamic calculation considering pressure(P), temperature(T) and gas composition(C) as variables in $C_3H_8-SiCl_4-H_2$ system. During the calculation, the ratio of Cl/Si and C/Si is maintained to be 4 and 1, respectively, and H/Si ratio is varied from 2.67 to 15,000. The P-T-C diagram showed very steep phase boundary between SiC+C and SiC region perpendicular to H/Si axis and also showed SiC+Si region with very large H/Si value of ~6700. The diagram can be applied not only to the prediction of the deposited phase composition but to compositional variation due to the temperature distribution in the reactor. The P-T-C diagram could provide the better understanding of chemical vapor deposition of silicon carbide.

• 한국세라믹학회지
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• 제45권7호
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• pp.411-417
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• 2008

Aerosol Deposition Method (ADM) is a novel technique to grow ceramic thick films with high density and nano-crystal structure at room temperature. $^{1,2)}$ For these unique advantages of ADM, it would be applied to the fabrication process of 3-D integration ceramic modules effectively. However, it is critical to control the properties of starting powders, because a film formation through ADM is achieved by impaction and consolidation of starting powders on the substrates. We fabricated alumina thick films by ADM for the application to integral substrates for RF modules. When the as-received alumina powders were used as a starting material without any treatments, it was observed that the dielectric properties of as-deposited alumina films, such as relative permittivity and loss tangent, showed high dependency on the frequency. In this study, some techniques of powder pre-treatments to improve the dielectric properties of alumina thick films will be shown and the effects of starting powders on the properties of AD films will be discussed.