• Applied Microscopy
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• 제50권
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• pp.7.1-7.10
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• 2020

Tantalum nitride (TaN_x) thin films were grown utilizing an inductively coupled plasma (ICP) assisted direct current (DC) sputtering, and 20-100% improved microhardness values were obtained. The detailed microstructural changes of the TaN_x films were characterized utilizing transmission electron microscopy (TEM), as a function of nitrogen gas fraction and ICP power. As nitrogen gas fraction increases from 0.05 to 0.15, the TaN_x phase evolves from body-centered-cubic (b.c.c.) TaN_0.1, to face-centered-cubic (f.c.c.) δ-TaN, to hexagonal-close-packing (h.c.p.) ε-TaN phase. By increasing ICP power from 100 W to 400 W, the f.c.c. δ- TaN phase becomes the main phase in all nitrogen fractions investigated. The higher ICP power enhances the mobility of Ta and N ions, which stabilizes the δ-TaN phase like a high-temperature regime and removes the micro-voids between the columnar grains in the TaN_x film. The dense δ-TaN structure with reduced columnar grains and micro-voids increases the strength of the TaN_x film.

• 한국재료학회지
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• 제10권1호
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• pp.21-28
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• 2000

내열금속인 W, Ti와 이들의 질화물인 $W_2$N, TiN 박막을 이용하여 탄화규소 ohmic 접촉을 연구하였다. 열처리 온도에 따른 고온 안정성과 전기적 특성 및 상호 확산 억제 특성을 고찰함으로써 이들 질화물의 고온에서 안정한 ohmic 접촉으로 이용가능성을 조사하였다. 새로운 유기화합물 원료인 bis-trimethylsilylmethane을 이용하여 화학기상 증착법으로 증착한 단결정 $\beta$-SiC 박막과 W이 가장 낮은 접촉 비저항, 2.17$\times$10(sup)-5Ω$\textrm{cm}^2$를 보였으며, Ti 계열은 상대적으로 높은 접촉 비저항 값을 나타내었다. 이들 전극 위에 산화 방지막으로 Pt 박막을 증착함으로써 전극의 산화를 막을 수 있었으며, 질화물 전극은 고온에서 금속접촉에 비해 안정한 전기적 특성을 나타내었고, 상호 확산 방지 특성 면에도 우수한 특성을 지니고 있음을 알 수 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 Techno-Fair 및 추계학술대회 논문집 전기물성,응용부문
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• pp.117-118
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• 2008

The $V_{1.85}W_{0.15}O_5$ thin films deposited on Pt/Ti/$SiO_2$/Si substrates by RF sputtering method exhibited fairly good TCR and dielectric properties. It was found that film crystallinity, dielectric properties, and TCR properties were strongly dependent upon the annealing temperature. The dielectric constants of the $V_{1.85}W_{0.15}O_5$ thin films annealed at $400^{\circ}C$ were 38.11, with a dielectric loss of 1%, respectively. Also, the TCR values of the $V_{1.85}W_{0.15}O_5$ thin films annealed at $400^{\circ}C$ were about -3.45%/K.

• 한국정밀공학회지
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• 제20권1호
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• pp.144-150
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• 2003

When WC and group IV elements are added to Ti(C,N)-Ni substrate, microstructures of the cermet is changed. The microstructure gives direct effect on the property of the material. In this study, the amount of WC and group W elements of Ti(C,N) cermet tool was investigated. The composition of WC was changed from 5 to 20wt% to determine the effect of WC on the cutting performance of cermet tool. The more WC was added, the longer the tool life of the cermet tool was. The cermet with 20wt% WC showed the best fracture toughness. The effect of group W elements; ZrC, ZrN and HfC was also investigated by adding each of them to manufacture the cermet tool with fixed l4wt% WC composition. The cermet with 1wt% ZrC and 14wt% WC showed the best cutting performance among the investigated cermet tools.

• 한국자기학회지
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• 제15권2호
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• pp.130-132
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• 2005

Tungsten carbon nitride (W-C-N) thin films were produced by reactive radio frequency (RF) magnetron sputter-ing of tungsten in $Ar-N_2$ gas mixture. The effects of the variation of nitrogen partial pressure on the composition, and structural properties of these films as well as the influence of post-deposition annealing have been studied. When $La_{0.67}Sr_{0.33}MnO_3$ was coated on the W-C-N/Si substrate, coercivity ($H_c$) and magnetization at room temperature shows 58.73 Oe, and 29.4 emu/cc, respectively. In order to improve the diffusion barrier characteristics, we have studied the impurity behaviors to control the ratios of nitrogen and carbon concentrations.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1999년도 추계학술발표강연 및 논문개요집
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• pp.76-76
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• 1999

Low resistance ohmic contacts to the Si-doped InGaN(~$\times$10$^{19}$ ㎤) were obtained using the W metallization schemes. Specific contact resistance decreased with increasing annealing temperature. The lowest resistance is obtained after a nitrogen ambient annealing at 95$0^{\circ}C$ for 90s, which results in a specific contact resistance of 2.75$\times$10$^{-8}$ Ω$\textrm{cm}^2$. Interfacial reactions and surface are analyzed using x-ray diffraction, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The X-ray diffraction results show that the reactions between the W film and the InGaN produce a $\beta$-W$_2$N phase at the interface. TEM results also show that the $\beta$-W$_2$N has a rough interface, which increase contact area. It shows that the morphology of the contacts is stable up to a temperature as high as 95$0^{\circ}C$. Possible mechanisms are proposed to describe the annealing temperature dependence of the specific contact resistance.

• 천문학회지
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• 제38권2호
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• pp.257-260
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• 2005

We have mapped the W 3 giant molecular cloud in the $C^o\;^3P_1-^3 P_o$ ([CI]) line with the Mount Fuji Submillimeter-wave Telescope. The [CI] emission is extended over the molecular cloud, having peaks at three star forming clouds; W 3(Main), W 3(OH), and AFGL 333. The [CI] emission is found to be strong in the AFGL 333 cloud. We have also observed the $C^{18}O,\;CCS,\;N_2H^+$, and $H^{13}CO^+$ lines by using the Nobeyama Radio Observatory 45 m telescope. In the AFGL 333 cloud, we find two massive cores, which are highly gravitationally bound and have no sign of active star formation. The high [$C^o$]/[CO] and [CCS]/[$N_2H^+$] abundance ratios suggest that the AFGL 333 cloud is younger than the W 3(Main) and W 3(OH) clouds.

• 한국전자파학회논문지
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• 제27권1호
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• pp.76-79
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• 2016

본 논문에서는 ETRI에서 개발된 50 W GaN-on-SiC HEMT 소자를 이용하여 X-band에서 동작하는 50 W 펄스 전력증폭기의 개발 결과를 정리하였다. 제작된 50 W GaN HEMT 소자는 $0.25{\mu}m$의 게이트 길이를 갖고, 총 게이트 폭은 12 mm인 소자이다. 펄스 전력증폭기는 9.2~9.5 GHz 주파수 대역에서 50 W의 출력전력과 6 dB의 전력이득 특성을 나타내었다. 전력소자의 전력밀도는 4.16 W/mm이다. 제작된 GaN-on-SiC HEMT 소자와 전력증폭기는 X-대역 레이더 시스템 등 다양한 응용분야에 적용이 가능할 것으로 판단된다.

• 대한화학회지
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• 제31권3호
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• pp.207-214
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• 1987

염화벤질의 가용매분해반응에 대한 속도를 $1{\sim}1600bar$ 압력범위까지 변화시켜 가면서 온도 30 및 $40^{\circ}C$에서 측정하였다. In k대 압력의 실험결과는 압력에 따라 이차함수형으로 변화하였으며, 이로부터 활성화부피(${\Delta}V^{\neq}$)와 활성화 압축율(${\Delta}{\beta}^{\neq}$)의 값을 얻었다. In k를 용매파라미터($Q_w$) 및 ln $C_w$의 함수로 도시한 결과 이들 사이의 관계는 본 연구의 반응이 $S_N$1메카니즘으로 진행됨을 나타내었다. 이 전에 연구된 결과들과 비교한 결과 ${\mid}{{\Delta}V_0}^{\neq}{\mid}$와 n 값의 증가 순은 각각 p-Cl>p-H>p-$CH_3\;와\;p-$CH_3>p-H>p-Cl$이었다. 이로부터 $p-CH_3$ 치환체는 $S_N1(1)$ 성격이 강하며, 반면 p-Cl는 ${S_N}1(2)$ 성격이 나타남을 알았다.

• 대한수학회보
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• 제31권1호
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• pp.105-113
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• 1994

In the course of study of dendroids, Czuba [3] introduced a notion of $R^{i}$ -continua which is a generalization of R-arc [1]. He showed a new class of non-contractible dendroids, namely of dendroids which contain an $R^{i}$ -continuum. Subsecequently Charatonik [2] attempted to extend the notion into hyperspace C(X) of metric continuum X. In so doing, there were some oversights in extending some of the results relating $R^{i}$ -continua of dendroids for metric continua. In fact, Proposition 1 in [2] is false (see example C below) and his proof of Theorem 6 in [2] is not correct (Take Example 4 in [4] with K = [e,e'] as an $R^{1}$-continuum of X and work it out. Then one seens that K not .mem. K as he claimed otherwise.). The aims of this paper are to introduce a notion of w-regular convergence which is weaker than 0-regular convergence and to prove that the w-regular convergence of a sequence {Xn}$^{\infty}$$_{n=1}$ to $X_{0}$ of subcontinua of a metric continuum X is a necessary and sufficient for the sequence {C( $X_{n}$)}$^{\infty}$$_{n=1}$ to converge to C( $X_{0}$ ), and also to prove that if a metric continuum X contains an $R^{i}$ -continuum with w-regular convergence, then the hyperspace C(X) of X contains $R^{i}$ -continuum.inuum.uum.