• Transactions on Electrical and Electronic Materials
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• 제7권1호
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• pp.16-20
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• 2006

In this paper, we investigated the effects of short-term oxygen plasma treatment of semiconducting silicone layer to improve interfacial performances in joints prepared with a insulating silicone materials. Surface characterizations were assessed using contact angle measurement and x-ray photoelectron spectroscopy (XPS), and then adhesion level and electrical performance were evaluated through T-peel tests and electrical breakdown voltage tests of treated semi-conductive and insulating joints. Plasma exposure mainly increased the polar component of surface energy from $0.21\;dyne/cm^2$ to $47\;dyne/cm^2$ with increasing plasma treatment time and then leveled off. Based on XPS analysis, the surface modification can be mainly ascribed to the creation of chemically active functional groups such as C-O, C=O and COH on semi-conductive silicone surface. This oxidized rubber layer is inorganic silica-like structure of Si bound with three to four oxygen atoms ($SiO_x,\;x=3{\sim}4$). The oxygen plasma treatment produces an increase in joint strength that is maximum for 10 min treatment. However, due to brittle property of this oxidized layer, the highly oxidized layer from too much extended treatment could be act as a weak point, decreasing the adhesion strength. In addition, electrical breakdown level of joints with adequate plasma treatment was increased by about $10\;\%$ with model samples of joints prepared with a semi-conducting/ insulating silicone polymer after applied to interface.

• 한국광학회:학술대회논문집
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• 한국광학회 1991년도 제6회 파동 및 레이저 학술발표회 Prodeedings of 6th Conference on Waves and Lasers
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• pp.80-80
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• 1991

1 GW급 옥소레이저를 직경과 깊이가 각각 0.5 mm에서 1.5 mm 사이에 있는 12 종류의 몰리브덴(Mo, Z=42) 홈 표적에 집속시켜서 발생하는 X-선의 세기를 측정하였다. 이때의 X-선 세기를 평면 표적의 경우와 비교하여 홈 표적에서의 효과를 조사하였다. X-선의 세기는 20 A 이하의 단파장을 통과시키는 필터뒤에 X-선 두어 측정하였으며 홈 표적에서의 X-선 세기는 평면 표적의 약 2 배가 됨을 보았다. 이 결과는 홈 표적에서의 플라즈마 감금효과에 의해 정성적으로ㅅ 성명 되었다.

• 한국재료학회지
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• 제22권4호
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• pp.185-189
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• 2012

We report plasma-assisted molecular beam epitaxy of $In_XGa_{1-X}N$ films on c-plane sapphire substrates. Prior to the growth of $In_XGa_{1-X}N$ films, GaN film was grown on the nitride c-plane sapphire substrate by two-dimensional (2D) growth mode. For the growth of GaN, Ga flux of $3.7{\times}10^{-8}$ torr as a beam equivalent pressure (BEP) and a plasma power of 150 W with a nitrogen flow rate of 0.76 sccm were fixed. The growth of 2D GaN growth was confirmed by $in-situ$ reflection high-energy electron diffraction (RHEED) by observing a streaky RHEED pattern with a strong specular spot. InN films showed lower growth rates even with the same growth conditions (same growth temperature, same plasma condition, and same BEP value of III element) than those of GaN films. It was observed that the growth rate of GaN is 1.7 times higher than that of InN, which is probably caused by the higher vapor pressure of In. For the growth of $In_xGa_{1-x}N$ films with different In compositions, total III-element flux (Ga plus In BEPs) was set to $3.7{\times}10^{-8}$ torr, which was the BEP value for the 2D growth of GaN. The In compositions of the $In_xGa_{1-x}N$ films were determined to be 28, 41, 45, and 53% based on the peak position of (0002) reflection in x-ray ${\theta}-2{\theta}$ measurements. The growth of $In_xGa_{1-x}N$ films did not show a streaky RHEED pattern but showed spotty patterns with weak streaky lines. This means that the net sticking coefficients of In and Ga, considered based on the growth rates of GaN and InN, are not the only factor governing the growth mode; another factor such as migration velocity should be considered. The sample with an In composition of 41% showed the lowest full width at half maximum value of 0.20 degree from the x-ray (0002) omega rocking curve measurements and the lowest root mean square roughness value of 0.71 nm.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.337-337
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• 2012

Dye sensitized solar cell (DSSC) having high efficiency with low cost was first reported by Gr$\ddot{a}$tzel et al. Many DSSC research groups attempt to enhance energy conversion efficiency by modifying the dye, electrolyte, Pt-coated electrode, and $TiO_2$ films. However, there are still some problems against realization of high-sensitivity DSSC such as the recombination of injected electrons in conduction band and the limited adsorption of dye on $TiO_2$ surface. The surface of $TiO_2$ is very important for improving hydrophilic property and dye adsorption on its surface. In this paper, we report a very efficient method to improve the efficiency and stability of DSSC with nano-structured $TiO_2$. Atmospheric plasma system was utilized for nitrogen plasma treatment on nano-structured $TiO_2$ film. We confirmed that the efficiency of DSSC was significantly dependent on plasma power. Relative in the $TiO_2$ surface change and characteristics after plasma was investigated by various analysis methods. The structure of $TiO_2$ films was examined by X-ray diffraction (XRD). The morphology of $TiO_2$ films was observed using a field emission scanning electron microscope (FE-SEM). The surface elemental composition was determined using X-ray photoelectron spectroscopy (XPS). Each of plasma power differently affected conversion efficiency of DSSC with plasma-treated $TiO_2$ compared to untreated DSSC under AM 1.5 G spectral illumination of $100mWcm^{-2}$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 춘계학술대회 논문집
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• pp.285-288
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• 1997

Generally the high dielectric films, such as PZT(Pb(Z $r^{1-x}$ $Ti_{x}$ ) $O_3$) and BST(B $a_{l-x}$S $r_{x}$ Ti $O_3$) have been formed on the Pt thin films. However it is generally known that the dry etching of Pt is difficult because of its chemical stability. So, the dry etching of Pt remains at the preliminary work. Therefore, in this study, Pt etching mechanism was investigated with Ar/C $l_2$gas plasma by using XPS(X-ray photoelectron spectroscopy) and QMS(Quadrupole mass spectrometry). Ion current density was measured with Ar/C $l_2$gas plasma by using single Langmuir probe. XPS results shoved that the atomic % of Cl element on the etched Pt sample increased with increasing Ar/(Ar+C $l_2$). And QMS results showed that the increase of Ar partial pressure in the plasma resulted in the improvement of C $l_2$dissociation and Cl redical formation and simultaniously the increase of ion bombardment effects.s.s.

• 한국표면공학회지
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• 제36권1호
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• pp.79-84
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• 2003

$WC-Ti_{1}$ -xA $l_{x}$ N multilayered coatings are performed by their periodically repeated structures of lamellae of WC-Ti/$WC-Ti_{1}$ -xA $l_{x}$ Nmaterials. The $WC-Ti_{1}$ -xA $l_{x}$ N coatings with variable Al content were deposited onto AISI D2 steel by cathodic arc deposition (CAD) method. The electrochemical behavior of multilayered $WC-Ti_{1}$ -xA $l_{x}$ N coatings with different phases (WC- Ti$0.6/Al_{0.4}$ N, $WC-Ti_{0.53}$$Al_{0.47}$N, $WC-Ti_{0.5}$ $Al_{0.5}$ N and $WC-Ti_{ 0.43}$$Al_{0.57}$ N) was investigated in deaerated 3.5% NaCl solution at room temperature. The corrosion behaviors for the multilayered coatings were investigated by electrochemical techniques (potentiodynamic polarization) and surface analyses (X-ray diffraction (XRD), scanning electron microscopy (SEM), and glow discharge optical emission spectroscopy (GDOES)). In the petentiodynamic polarization test, the corrosion current density of $WC-Ti_{0.5}$$Al_{0.5}$N was lower than others.

• Bulletin of the Korean Chemical Society
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• 제31권2호
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• pp.397-400
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• 2010

Zirconium oxide thin films deposited on the p-type Si(100) substrates by radio-frequency (RF) reactive magnetron sputtering with different plasma gas ratios have been studied by using spectroscopic ellipsometry (SE), atomic force microscopy (AFM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The deposition of the films was monitored by the oxygen gas ratio which has been increased from 0 to 80%. We found that the thickness and roughness of the zirconium oxide thin films are relatively constant. The XRD revealed that the deposited thin films have polycrystalline phases, Zr(101) and monoclinic $ZrO_2$ ($\bar{1}31$). The XPS result showed that the oxidation states of zirconium suboxides were changed to zirconia form with increasing $O_2$ gas ratio.

• Journal of Korean Vacuum Science & Technology
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• 제2권1호
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• pp.49-54
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• 1998

The effect of deposition paratmeters on the solid-phase crystallization of amorphous silicon films deposited by plasma-enhanced chemical vapor deposition has been investigated by x-ray diffraction. The amorphous silicon films were prepared on Si(100) wafers using SiH4 gas with and without H2 dilution at the substrate temperatures between 12$^{\circ}C$ and 38$0^{\circ}C$. The R. F. powers and the deposition pressures were also varied. After crystallizing at $600^{\circ}C$ for 24h, the films exhibited (111), (220), and (311) x-ray diffraction peaks. The (111) peak intensity increased as the substrate temperature decreased, and the H dilution suppressed the crystallization. Increasing R.F. powers within the limits of etching level and increasing deposition pressures also have enhanced the peak intensity. The peak intensity was closely related to the deposition rate, which may be an indirect indicator of structural disorder in amorphous silicon films. Our results are consistent with the fact that an increase of the structural disorder I amorphous silicon films enhances the grain size in the crystallized films.

• 천문학회지
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• 제36권2호
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• pp.61-66
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• 2003

We have examined the relationship between the speeds of coronal mass ejections (CMEs) and the GOES X-ray peak fluxes of associated flares. Noting that previous studies were possibly affected by projection effects and random association effects, we have considered two sets of carefully selected CME-flare events: four homologous events and four well-observed limb events. In the respective samples, good correlations are found between the CME speeds and the GOES X-ray peak fluxes of the associated flares. A similarly good correlation is found for all eight events of both samples when the CME speeds of the homologous events are corrected for projection effect. Our results suggest that a close relationship possibly exists between CME kinematics and flaring processes.

• 한국진공학회지
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• 제9권1호
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• pp.16-23
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• 2000

The epitaxial growth of $CeO_2$ films has been investigated on three different substrates-Si(111), $SrTiO_3$(001), and MgO(001)-over wide range of growth parameters using oxygen-plasma-assisted molecular beam epitaxy. Pure-phase, single-crystalline epitaxial films of $CeO_2$ (001) have been grown only on $SrTiO_3$(001). We discuss the growth conditions in conjunction with the choice of substrates required to synthe-size this oxide, as well as the associated characterization by menas of x-ray diffraction, reflection high-energy electron diffraction, low-energy electron diffraction, and x-ray photoelectron spectroscopy and diffraction. Successful growth of single crystalline $CeO_2$ depends critically on the choice of substrate and is rather insensitive to the growth conditions studied in this investigation. $CeO_2$(001) films on $SrTiO_3$exhibit the sturcture of bulk $CeO_2$ without surface reconstructions. Ti outdiffusion is observed on the films grown temperatures above $650^{\circ}C$.