• Bulletin of the Korean Chemical Society
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• v.11 no.5
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• pp.460-463
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• 1990

The normal and fluorinated high-Tc superconducting materials, $YBa_2Cu_3O_{7-x}F_y$with $0.25{\leq}x{\leq}0.55\;and\;0.00{\leq}y{\leq}0.30$, were synthesized to investigate the dopping effect of fluorine atom on the superconductivity of Y123 and studied by X-ray diffraction analysis and electron probe microanalysis, resistivity and thermopower measurements, and polarized micro-Raman spectroscopy. The reproducible micro-Raman spectra were recorded and analyzed. The coherent assignments could be suggested for the spectra of normal and fluorinated samples. The fluorine atoms introduced were found to be substituted for oxygen in pyramidal Cu-O units rather than in Cu-O chains. The unit cell parameters were decreased upon the substitution of oxygen by fluorine atom. From the decreasing cell parameters and Tc, the increasing thermopower, and the possible assignments of the vibrational modes, it could be suggested that the dopping of fluorine atom localizes the superconducting electrons in Y123.

• Bulletin of the Korean Chemical Society
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• v.13 no.2
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• pp.131-135
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• 1992

High-Tc superconducting materials, $HoBa_2Cu_3O_{7-x}F_y$ with $0.0{\leq}y{\leq}0.5$, were synthesized by ceramic method and studied by X-ray diffraction, thermogravimetric analysis, differential thermal analysis, scanning electron microscopy and resistivity measurement. From the X-ray diffraction data, it was found that the samples had only single phase of which lattice volumes were decreased in proportional to the amount of fluorine, which indicated that the relatively small fluorine atoms are effectively substituted for the oxygen sites. Also, an anomalous phenomenon appeared that the peak intensities of (001) planes were greatly increased as fluorine contents increased. SEM photographs revealed that the grain sizes were enlarged progressively with fluorine contents. This fact could be explained along with DTA & TGA data that the incorporation of fluorine gave rise to lowering the melting point. Tc decreased as the incorporation of fluorine content increased. This implies that the superconducting electrons are perturbed due to the substitution of electronegative fluorine atom.

• Bulletin of the Korean Chemical Society
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• v.11 no.3
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• pp.191-194
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• 1990

High-Tc superconducting materials, $YBa_2Cu_3O_xF_y$ with $x{\leq}6.89\;and\;0.25{\leq}y{\leq}0.35$, were prepared and Studied by X-ray diffraction, magnetic susceptibility and resistivity measurement. Under given conditions, reproducible resistivities were obtained, which increased with increase in the amount of fluorine. The introduced fluorine atoms were found to be localized in pyramidal Cu-O units rather than in Cu-O chains. It is suggested that the localized fluorine atom increases the electronic lolcalization of the superconducting electrons.

• Journal of the Korean Vacuum Society
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• v.5 no.2
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• pp.169-174
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• 1996

The applications of the high density plasma sources to the etching in semiconductor fabrication process are actively studied because of the more strict requirement from the dry etching process due to shrinking down of the critical dimension. But in the oxide etching with the high density plasma sources, abundant fluorine atoms released from the flurocarbon feed gas make it difficult to get the highly selective $SiO_2/Si$ etching. In this study, to improve the $SiO_2/Si$ etch selectivity through the control of the radical loss channels, we propose the wall heating , one of methods of controlling loss mechanisms. With appearance mass spectroscopy(AMS) and actinometric optical emission spectroscopy(OES), the increase of both radicals impinging on the substrate and existing in bulk plasma, and the decrease of the fluorine atom with wall temperature are observed. As a result, a 40% improvement of the selectivity was achieved for the carbon rich feed gas.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1504-1507
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• 2009

In this paper, the etching behavior of ZnO in $CF_4$ plasma mixed Ar was investigated. Previously, the etch rate in $CF_4$/Ar plasma was reported that it is slower than that in Cl containing plasma. But, plasma included Cl atom can produce the by-product such as $ZnCl_2$. In order to solve this film contamination, no Cl containing etching gas is required. We controlled the etching parameter such as source power, substrate bias power, and $CF_4$/Ar gas ratio to acquire the fast etch rate using a ICP etcher. We accomplished the etching rate of 144.85 nm/min with the substrate bias power of 200W. As the energetic fluorine atoms were bonded with Zinc atoms, the fluoride zinc crystal ($ZnF_2$) was observed by X-ray photoelectron spectroscopy (XPS).

• Korean Journal of Pharmacognosy
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• v.7 no.3
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• pp.159-169
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• 1976

The present review records the known structures of more than 80 organic compounds containing halogens, which may be considered naturally occurring. The format of the review is based on the viewpoint of biochemists. Compounds containing one type of halogen atom have been placed in one of four major division, i.e., structures possessing fluorine, chlorine, bromine or iodine covalently bonded to carbon. Within each major division molecular structures are given along with the species from which the compounds have been isolated, The biological significance, if any, is also mentioned.

• KSTLE International Journal
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• v.6 no.1
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• pp.13-16
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• 2005

Friction characteristics at nano-scale of self-assembled monolayers (SAMs) having different chain lengths and end groups were experimentally studied.51 order to understand the effect of the chain length and end group on the nano-scalefriction: (1) two different SAMs of shorter chain lengths with different end groups such as methyl and phenyl groups, and (2)four different kinds of SAMs having long chain lengths (C10) with end groups of fluorine and hydrogen were coated on siliconwafer (100) by dipping method and Chemical Vapour Deposition (CVD) technique. Their nano-scale friction was measuredusing an Atomic Force Microscopy (AFM) in the range of 0-40 nN normal loads. Measurements were conducted at the scanning speed of 2 $mu$m/s for the scan size of 1$mu$m x 1 $mu$m using a contact mode type $Si_3N_4$ tip (NPS 20) that had a nominal spring constant0.58 N/m. All experiments were conducted at anlbient temperature (24 $pm$1$circ$C) and relative humidity (45 $pm$ 5%). Results showedthat the friction force increased with applied normal load for all samples, and that the silicon wafer exhibited highest frictionwhen compared to SAMs. While friction was affected by the inherent adhesion in silicon wafer, it was influenced by the chainlength and end group in the SAMs. It was observed that the nano-friction decreased with the chain length in SAMs. In the caseof monolayers with shorter length, the one with the phenyl group exhibited higher friction owing to the presence of benBenerings that are stiffer in nature. In the case of SAMs with longer chain length, those with fluorine showed friction values relativelyhigher than those of hydrogen. The increase in friction due to the presence of fluorine group has been discussed with respect tothe siBe of the fluorine atom.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.168-171
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• 2017

In this study, we observed degradation mechanism of FKM O-ring by X-ray photoelectron spectroscopy(XPS) at atmosphere condition. FKM O-ring had 3.53mm of cross-sectional diameter and 91.67mm of inner diameter. After thermal degradation, oxygen atom concentration of FKM O-ring was increased to 20.39%, and fluorine atom concentration was decreased to 8.29%. We observed that degradation reaction occurred by oxidation reaction. By C1s and F1s peak analysis, we confirmed that oxidation reaction usually occurred at C-F bonding of FKM main chain. Also, carboxyl group(C-OH, C=O, O=C-O) produced by oxidation reaction from O1s peak analysis.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.244.2-244.2
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• 2013

Contact Pattern을 Plasma Etching을 통해 Pattering 공정을 진행함에 있어서 Plasma 내에 존재하는 High Energy Ion 들의 Bombardment 에 의해, Contact Bottom 의 Silicon Lattice Atom 들은 Physical 한 Damage를 받아 Electron 의 흐름을 방해하게 되어, Resistance를 증가시키게 된다. 또한 Etchant 로 사용되는 Fluorine 과 Chlorine Atom 들은, Contact Bottom 에 Contamination 으로 작용하게 되어, 후속 Contact 공정을 진행하면서 증착되는 Ti 나 Co Layer 와 Si 이 반응하는 것을 방해하여 Ohmic Contact을 형성하기 위한 Silicide Layer를 형성하지 못하도록 만든다. High Aspect Ratio Contact (HARC) Etching 을 진행하면서 Contact Profile을 Vertical 하게 형성하기 위하여 Bias Power를 증가하여 사용하게 되는데, 이로부터 Contact Bottom에서 발생하는 Etchant 로 인한 Damage 는 더욱 더 증가하게 된다. 이 Damage Layer를 추가적인 Secondary Damage 없이 제거하기 위하여 본 연구에서는 원자층 식각방법(Atomic Layer Etching Technique)을 사용하였다. 실험에 사용된 원자층 식각방법을 이용하여, Damage 가 발생한 Si Layer를 Secondary Damage 없이 효과적으로 Control 하여 제거할 수 있음을 확인하였으며, 30 nm Deep Contact Bottom 에서 Damage 가 제거될 수 있음을 확인하였다. XPS 와 Depth SIMS Data를 이용하여 상기 실험 결과를 확인하였으며, SEM Profile 분석을 통하여, Damage 제거 결과 및 Profile 변화 여부를 확인하였으며, 4 Point Prove 결과를 통하여 결과적으로 Resistance 가 개선되는 결과를 얻을 수 있었다.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3621-3628
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• 2013

Novel 5'-deoxythreosyl purine phosphonic acid analogues containing a 2'-electropositive moiety such as fluorine atom, were designed and synthesized from commercially available 1,3-dihydroxy acetone. Condensation successfully proceeded from a glycosyl donor 6 under Vorbr$\ddot{u}$ggen conditions and cross-metathesis gave the desired phosphonate analogues 7a, 7b, 17a and 17b. The synthesized nucleoside phosphonic acid analogues 13, 16, 23, 26, 28 were subjected to antiviral screening against HIV-1. The bis(SATE) adenine analogue 28 exhibited significant in vitro activities against HIV-1.