• 한국통신학회논문지
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• 제39A권6호
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• pp.310-321
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• 2014

정사각형 천공이 $2{\times}2$ 배열된 정사각형 패치 안테나에 근접 결합 급전을 이용하여 기판 두께와 천공의 위치 및 크기가 안테나의 대역폭과 방사특성에 미치는 영향에 대하여 연구하였다. 안테나 기판과 급전 기판의 두께가 두꺼워질수록 방사특성의 저하 없이 대역폭이 증가 되었다. 천공 중심의 위치를 패치 길이 방향 가장자리로 이동시키는 경우 방사특성의 큰 저하 없이 대역폭을 증가시킬 수 있었다. 천공 중심의 위치를 패치 폭 방향으로 이동시키는 경우 중심 위치가 대역폭과 방사특성에 미치는 영향이 매우 작았다. 천공의 크기가 작아질수록 대역폭은 증가되고 방사특성은 향상되었다.

• 한국자기학회지
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• 제15권2호
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• pp.125-129
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• 2005

$A1_2O_3$ 기판을 하지층으로 하는 Ba-ferrite 박막을 pulsed laser deposition system으로 제조하여 결정학적 및 자기적 성질을 SEM, $M\ddot{o}ssbauer$ 분광법 및 VSM을 사용하여 연구하였다. Ba-ferrite박막은 $A1_2O_3$ 기판위에 PLD를 이용하여 기판온도 $400^{\circ}C$, 산소압력 0.1 Torr로 증착 하였고 증착 시간을 달리하여 두께 조절하였다. Ba-ferrite 박막은 5분 증착한 시료에서만 판상으로 결정이 형성되었음을 볼 수 있고 그보다 두꺼운 시료의 경우에는 침상모양과 판상모양이 임의의 방향으로 혼재되었음을 확인하였다. $M\ddot{o}ssbauer$ssbauer 분광법으로부터 측정된 Ba-ferrite결정 내 Fe 원자의 스핀 방향은 두께가 얇을수록 판상의 결정이 많이 존재하여 기판에 수직으로 정렬하려는 경향을 보이고 있다. VSM으로 측정한 자기이력곡선은 판상과 침상의 상이한 2가지 형태가 공존하는 것으로 나타났다.

• 한국재료학회지
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• 제19권8호
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• pp.452-456
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• 2009

In high-efficiency Cu(In,Ga)$Se_2$ solar cells, Na is doped into a Cu(In,Ga)$Se_2$ light-absorbing layer from sodalime-glass substrate through Mo back-contact layer, resulting in an increase of device performance. However, this supply of sodium is limited when the process temperature is too low or when a substrate does not supply Na. This limitation can be overcome by supplying Na through external doping. For Na doping, an NaF interlayer was deposited on Mo/glass substrate. A Cu(In,Ga)$Se_2$ absorber layer was deposited on the NaF interlayer by a three-stage co-evaporation process As the thickness of NaF interlayer increased, smaller grain sizes were obtained. The resistivity of the NaF-doped CIGS film was of the order of $10^3{\Omega}{\cdot}cm$ indicating that doping was not very effective. However, highest conversion efficiency of 14.2% was obtained when the NaF thickness was 25 nm, suggesting that Na doping using an NaF interlayer is one of the possible methods for external doping.

• 한국분말재료학회지
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• 제13권1호
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• pp.18-24
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• 2006

The brazing adhesion properties of Ag coated W-Ag electric contact on the Cu substrate have been investigated in therms of microstructure, phase equilibrium and adhesion strength. Precoating of Ag layer ($3{\mu}m$ in thickness) on the $W-40\%Ag$ contact material was done by electro-plating method. Subsequently the brazing treatment was conducted by inserting BCuP-5 filler metal (Ag-Cu-P alloy) layer between Ag coated W-Ag and Cu substrate and annealing at $710^{\circ}C$ in $H_2$ atmosphere. The optimum brazing temperature of $710^{\circ}C$ was semi-empirically calculated on the basis of the Cu atomic diffusion profile in Ag layer of commercial electric contact produced by the same brazing process. As a mechanical test of the electric contact after brazing treatment the adhesion strength between the electric contact and Cu substrate was measured using Instron. The microstructure and phase equilibrium study revealed that the sound interlayer structure was formed by relatively low brazing treatment at $710^{\circ}C$. Thin Ag electro-plated layer precoated on the electric contact ($3{\mu}m$ in thickness) is thought to be enough for high adhesion strength arid sound microstructure in interface layer.

• 한국전기전자재료학회논문지
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• 제22권5호
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• pp.425-430
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• 2009

$ZrO_2$ film was deposited by facing target sputtering (FTS) system on polyethylene naphthalate (PEN) substrate as a gas barrier layer for flexible organic light emitting devices (FOLEDs), In order to control the heat of the FTS system caused by the ion bombardment in the cathode compared with the conventional sputtering system, the process characteristics of the FTS apparatus are investigated under various sputtering conditions such as the distance between two targets ($d_{TT}$), the distance between the target and the substrate ($d_{TS}$), and the deposition time. The $ZrO_2$ film by the FTS system can reduce the damage on the films because the ion bombardment with high-energy particles like gamma-electrons, Moreover, the $ZrO_2$ film with optimized condition ($d_{TT}$=140 mm) as a function of the distance from center to edge showed a very uniform thickness below 5 % for a deposition time of 3 hours, which can improve the interface property between the anode and the plastics substrate for flexible displays, It is concluded that the $ZrO_2$ film prepared by the FTS system can be applied as a gas barrier layer or an interlayer between the anode and the plastic substrate with good properties of an uniform thickness and a low deposition-temperature.

• 한국진공학회지
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• 제14권4호
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• pp.201-206
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• 2005

본 연구에서는 HVPE (Hydride Vapor Phase Epitaxy) 방법으로 Si 위에 GaN/AIN/Al/Si 구조를 제작하고, AlN 버퍼층의 두께에 따른 광학적 특성을 조사함으로써 효과적인 eaN 성장을 위한HVPE에서의 공정 방법을 개선하고자 하였다. 이를 위해 Al을 증착한 Si 기판과 그렇지 않은 경우를 PL측정을 통해 그 효과를 관찰하였고, $5{\AA}$ 두께의 Al 대해 AlN 버퍼층의 두께를 변화시켜가면서 GaN를 성장시켜 그 특성을 조사하였다. Al을 증착한 경우가 증착하지 않은 경우에 비해 광학적 특성이 우수한 것으로 나타났으며, AlN의 두께 변화에 대해서는 양질의 GaN를 얻기 위한 최적의 두께는 약 $260{\AA}$ 인 것으로 나타났다. 이 경우 SEM을 이용한 표면사진에서 GaN의 초기성장이 hexagonal형태로 성장되고 있음을 관찰할 수 있었다. 또한 XRD의 회절 패턴은 GaN가 {0001} 방향으로 우선 배향성을 가지고 성장되고 있음을 보여주고 있었다.

• 대한금속재료학회지
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• 제49권4호
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• pp.321-328
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• 2011

The 30 nm-thick Ni layers was deposited on a flexible polyimide substrate with an e-beam evaporation. Subsequently, we deposited a Si layer using a catalytic CVD (Cat-CVD) in a hydride amorphous silicon (${\alpha}$-Si:H) process of $T_{s}=180^{\circ}C$ with varying thicknesses of 55, 75, 145, and 220 nm. The sheet resistance, phase, degree of the crystallization, microstructure, composition, and surface roughness were measured by a four-point probe, HRXRD, micro-Raman spectroscopy, FE-SEM, TEM, AES, and SPM. We confirmed that our newly proposed Cat-CVD process simultaneously formed both NiSi and crystallized Si without additional annealing. The NiSi showed low sheet resistance of < $13{\Omega}$□, while carbon (C) diffused from the substrate led the resistance fluctuation with silicon deposition thickness. HRXRD and micro-Raman analysis also supported the existence of NiSi and crystallized (>66%) Si layers. TEM analysis showed uniform NiSi and silicon layers, and the thickness of the NiSi increased as Si deposition time increased. Based on the AES depth profiling, we confirmed that the carbon from the polyimide substrate diffused into the NiSi and Si layers during the Cat-CVD, which caused a pile-up of C at the interface. This carbon diffusion might lessen NiSi formation and increase the resistance of the NiSi.

• 한국전기전자재료학회논문지
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• 제15권6호
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• pp.539-542
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• 2002

The effect of the superconducting film thickness on the surface resistance has been investigated. Superconducting YBCO thin films have been grown on MgO substrates by pulsed laser deposition. The dependence of the orientation of YBCO film on thickness has been investigated by X-ray diffraction technique. X-ray diffraction indicated that the film orientation was changed by increasing the film thickness and by changing the substrate temperature. The microwave properties of the films with mixed orientations of a-axis and c-axis will be reported for the applications of microwave devices.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.142-142
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• 2003

The effects of film thickness on the dipolar relaxation of ferroelectric PbTiO$_3$ films were investigated in the microwave-frequency range. The dielectric constants ($\varepsilon$) and the dielectric losses (tan $\delta$) were successfully measured up to 30 ㎓ using interdigital capacitors. The PbTiO$_3$ thin films were deposited on the quartz substrate at room temperature and postannealed in oxygen atmosphere. As the film thickness increased, its grain size and tetragonality were enhanced. And the dipolar relaxation behavior began to appear in the thin films with approximately 20 nm thickness, since ferroelectric domains could not be formed hi small grains. The observed relaxation frequency (above 10 ㎓) was higher than the previous values reported in bulk ceramics. It can be correlated with the extremely small domain size of the thinfilms as shown by TEM. And, the Rayleigh constant [1] from domain wall motions was alsoinvestigated by LCR meter at 100 KHz.

• 대한전자공학회논문지
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• 제27권12호
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• pp.1852-1858
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• 1990

The sheet resistance and thickness of Ti-Silicides treated RTA at 600, 700, 800\ulcorner was measured with amount of BF2 implanted in Si substrate. And the profile of BF2 was studied by SIMS. The formation of TiSi2 starts at 700\ulcorner. The Ti-Silicides almost consist of TiSi2 and have a low resistivity about 16列 cm at 800\ulcorner. The sheet resistances of Ti-silicides increase and thicknesses of it decrease with increasing dose of BF2. Considering the results of SIMS and the thickness of native oxide, the decrease of thickness of Silicides chiefly results from the increase of native oxide thickness with increasing dopants.