• 한국세라믹학회:학술대회논문집
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• 한국세라믹학회 2003년도 추계총회 및 연구발표회 초록집
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• pp.131.2-131
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• 2003

• 대한화학회지
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• 제35권5호
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• pp.480-486
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• 1991

아닐린 및 o-클로로아닐린 용액내에서 브롬화에탄의 용해도를 5, 1.5$^{\circ}$ 및 25$^{\circ}$C에서 브롬화칼륨이 존재할 때와 존재하지 않을 때의 두 경우에 대하여 각각 측정하여 보았다. 브롬화칼륨이 존재하지 않을 때에 o-클로로아닐린에서 브롬화에탄의 용해도가 아닐린에서 보다 크다. 이것은 브롬화에탄과 o-클로로아닐린의 상호작용이 아닐린보다 더 강하다는 것을 나타낸다. 그리고 브롬화칼륨이 존재할 경우에는 용액내에서 브롬화에탄과 브롬화칼륨이 불안정한 착물이 생성된다. 이 착물을 여러 경우로 가정하여 계산하여 본 결과 1:1 착물일 때, 불안정 상수 K값이 비교적 일정한 값을 나타내었다. 그러므로 1:1 착물 $C_2H_5Br[\cdot}GaBr_3$가 형성됨을 알았으며, 이 착물은 용액내에서 다음 평형식에 의해서 이루어진다고 본다. $C_2H_5Br{\cdot}GaBr_3\;{\rightleftharpoons}\;C_2H_5Br+1/2Ga_2Br_6$ 브롬화칼륨과 브롬화에탄의 착물의 불안정도를 이와 대응하는 브롬화메탄과 비교하여 보았다. 또한 이 착물의 해리에 대한 엔탈피, 자유에너지 및 엔트로피 변화도 산출하였다.

• 한국정밀공학회지
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• 제25권9호
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• pp.32-37
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• 2008

Freestanding hydride vapor phase epitaxy grown GaN(Gallium Nitride) substrates subjected to various polishing methods were characterized for their surface and subsurface conditions, Although CMP(Chemical Mechanical Polishing) is one of the best approaches for reducing scratches and subsurface damages, the removal rate of Ga-polar surface in CMP is insignificant($0.1{\sim}0.3{\mu}m$/hr) as compared with that of N-polar surface, Therefore, conventional MP(Mechanical Polishing) is commonly used in the GaN substrate fabrication process, MP of (0001) surface of GaN has been demonstrated using diamond slurries with different abrasive sizes, Diamond abrasives of size ranging from 30nm to 100nm were dispersed in ethylene glycol solutions and mineral oil solutions, respectively. Significant change in the surface roughness ($R_a$ 0.15nm) and scratch-free surface were obtained by diamond slurry of 30nm in mean abrasive size dispersed in mineral oil solutions. However, MP process introduced subsurface damages confirmed by TEM (Transmission Electronic Microscope) and PL(Photo-Luminescence) analysis.

• JSTS:Journal of Semiconductor Technology and Science
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• 제14권2호
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• pp.163-168
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• 2014

Bottom gate thin-film transistors were fabricated using solution processed IGZO channel layers with various gallium composition ratios that were annealed on a hot plate. Increasing the gallium ratio from 0.1 to 0.6 induced a threshold voltage shift in the electrical characteristics, whereas the molar ratio of In:Zn was fixed to 1:1. Among the devices, the IGZO-TFTs with gallium ratios of 0.4 and 0.5 exhibited suitable switching characteristics with low off-current and low SS values. The IGZO-TFTs prepared from IGZO films with a gallium ratio of 0.4 showed a mobility, on/off current ratio, threshold voltage, and subthreshold swing value of $0.1135cm^2/V{\cdot}s$, ${\sim}10^6$, 0.8 V, and 0.69 V/dec, respectively. IGZO-TFTs annealed at $300^{\circ}C$, $350^{\circ}C$, and $400^{\circ}C$ were also fabricated. Annealing at lower temperatures induced a positive shift in the threshold voltage and produced inferior electrical properties.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.248.2-248.2
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• 2014

In this study, the optical properties and structural characteristics of gallium nitride (GaN) thin films prepared by radio frequency (RF) magnetron sputtering were investigated. Auger electron and X-ray photoelectron spectra showed that the deposited films consisted mainly of gallium and nitrogen. The presence of oxygen was also observed. The optical bandgap of the GaN films was measured to be approximately 3.31 eV. The value of the refractive index of the GaN films was found to be 2.36 at a wavelength of 633 nm. X-ray diffraction data revealed that the crystalline phase of the deposited GaN films changed from wurtzite to zinc-blende phase upon decreasing the sputtering gas pressure. Along with the phase change, a strong dependence of the microstructure of the GaN films on the sputtering gas pressure was also observed. The microstructure of the GaN films changed from a voided columnar structure having a rough surface to an extremely condensed structure with a very smooth surface morphology as the sputtering gas pressure was reduced. The relationship between the phase and microstructure changes in the GaN films will be discussed.

• 대한핵의학회지
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• 제35권4호
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• pp.280-285
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• 2001

We present a case of a 31 year-old male patient with tuberculous pericarditis with mediastinal mass that showed increased uptake on Gallium-67 image. Gallium-67 scan was performed to evaluate the activity of the superior mediastinal mass, which was detected on chest CT. A rim of intense activity around the heart was observed, but increased uptake was not seen in the mediastinum. However, on maximal contrast-enhanced SPECT images, a small focus of faint uptake was observed in the superior mediastinum. This finding implied that there was an active tuberculosis in the pericardium and inflammation in the superior mediastinal mass. This case demonstrated that Gallium-67 scinitigraphy was helpful for the diagnosis of tuberculous pericarditis.

• 한국진공학회지
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• 제13권4호
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• pp.182-188
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• 2004

이전의 연구에서의 소스 형태는 전기화학적 방법으로 에칭된 텅스텐 선에 코일형태의 히터를 부착한 것으로 액체금속을 직접 가열하는 방법이었다. 이전의 모델에서는 액체금속을 가열하는 과정에서 코일형태의 히터에 대한 과다한 전력소모가 발생함으로써 본 연구에서는 코일형태의 히터를 대체할 수 있는 새로운 방법을 제시하고 그의 특성을 연구하였다. Pre-etching된 250$\mu\textrm{m}$의 텅스텐 선을 7mm 단위로 절단, 이를 갈륨저장소로 만든 형태이다. 가열방식은 직접방식으로 갈륨을 저장소에 적재(loading)하는 과정과 빔의 안정도가 이전의 방법보다 더욱 향상되었음을 본 연구의 결과를 통해 볼 수 있다.

• 대한화학회지
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• 제38권3호
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• pp.208-213
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• 1994

니트로벤젠용액내에서의 i-브롬화브텔의 용해도를 19, 25, 40$^{\circ}C$에서 브롬화갈륨이 있을 때와 없을때에 각각 측정하여 보았다. 브롬화갈륨이 존재할 때에는 용액내에서 i-브롬화부틸과 브롬화갈륨의 1:1착물,$ i-C_4H9Br{\cdot}GaBr_3$가 형성된다. 이 착물형성의 instability constant K는 다음 식으로 계산된다. $i-C_4H9_Br{\cdot}GaBr_3{\rightleftharpoons}C_4H_9Br + 1/2Ga_2Br_6.$ 따라서 브로화갈륨과 각 브롬화알킬간의 착물형성의 안정도를 비교검토한 결과 이들 브롬화알킬의 carbonium ion의 안정도와 직접적인 관계가 있다고 본다.

• 대한화학회지
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• 제6권1호
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• pp.77-83
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• 1962

The solubilities of hydrogen bromide and methyl bromide in nitrobenzene and in 1,2,4-trichlorobenzene have been measured in the presence and absence of gallium bromide. When gallium bromide does not exist in the system, the solubilities of HBr and MeBr in nitrobenzene are greater than in 1,2,4-trichlorobenzene, indicating the greater basicity of nitrobenzene than 1,2,4-trichlorobenzene. When there exists gallium bromide in the system, the addition compounds, GaBr3·HBr and GaBr3·CH3Br, have been found to exist in solution. The addition compound of GaBr3·HBr is stable in nitrobenzene but unstable in 1,2,4-trichlorobenzene. On the other hand the addition compound of $GaBr_3{\cdot}CH_3Br$ is unstable in both solvents. All of these unstable addition compounds dissociate into components to large extents according to one of the following equilibria or both: $$GaBr_3{\cdot}RBr{\leftrightarrows}GaBr_3+RBr\;GaBr_3{\cdot}RBr{\leftrightarrows}1}2\;Ga_2Br_6+RBr$.$ where R denotes either hydrogen atom or methyl group.

• Bulletin of the Korean Chemical Society
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• 제28권1호
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• pp.17-28
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• 2007

Indium and gallium have emerged as useful metals in organic synthesis as a result of its intriguing chemical properties of reactivity, selectivity, and low toxicity. Although indium belongs to a main metal in group 13, its first ionization potential energy is very low and stable in H2O and O2. Therefore, indium-mediated organic reactions are of our current interest. On the basis of these properties of indium, many efficient indium-mediated organic reactions have been recently developed, such as the addition reactions of allylindium to carbonyl and iminium groups, the indium-mediated synthesis of 2-(2-hydroxyethyl)homoallenylsilanes, the indiummediated allylation of keto esters with allyl halides, sonochemical Reformatsky reaction using indium, the indium-mediated selective introduction of allenyl and propargyl groups at C-4 position of 2-azetidinones, the indium-mediated Michael addition and Hosomi-Sakurai reactions, the indium-mediated β-allylation, β- propargylation and β-allenylation onto α,β-unsaturated ketones, the highly efficient 1,4-addition of 1,3-diesters to conjugated enones by indium and TMSCl, and the intramolecular carboindation reactions. Also, we found gallium-mediated organic reactions such as addition reactions of propargylgallium to carbonyl group and regioselective allylgallation of terminal alkynes.