• Polymer(Korea)
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• v.36 no.3
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• pp.393-400
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• 2012

The characteristics of indium tin oxide (ITO) thin film deposited on polyethersulfone (PES) film by low temperature E beam has been studied for the flexible photovoltaic devices. It was found that the substrate temperature in the deposition process affected the crystallization behavior of ITO during the post low temperature annealing process. Higher substrate temperature resulted in the increase of crystallinity of annealed ITO. Consequently, the lowering of sheet resistivity and better transmittance were obtained. Crystallization of ITO during the annealing process was facilitated by using oxygen gas in the deposition process and resulted in the enhancement on sheet resistivity and transmittance of ITO. The surface roughness of PES film prohibited the crystallization of ITO during the annealing process and it caused the increase of sheet resistivity and the decrease of transmittance of ITO.

• Journal of the Korean Ceramic Society
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• v.51 no.1
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• pp.43-50
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• 2014

We fabricated undoped and Sb-doped $SnO_2$ thin films on glass substrates by a pulsed laser deposition (PLD) process. Undoped and 2 - 8 wt% $Sb_2O_3$-doped $SnO_2$ targets with a high density level of ~90% were prepared by the spark plasma sintering (SPS) process. Initially, the effects of the deposition temperature on undoped $SnO_2$ thin films were investigated in the region of $100-600^{\circ}C$. While the undoped $SnO_2$ film exhibited the lowest resistivity of $1.20{\times}10^{-2}{\Omega}{\cdot}cm$ at $200^{\circ}C$ due to the highest carrier concentration generated by the oxygen vacancies, 2 wt% Sb-doped $SnO_2$ film exhibited the lowest resistivity value of $5.43{\times}10^{-3}{\Omega}{\cdot}cm$, the highest average transmittance of 85.8%, and the highest figure of merit of 1202 ${\Omega}^{-1}{\cdot}cm^{-1}$ at $400^{\circ}C$ among all of the doped films. These results imply that 2 wt% $Sb_2O_3$ is an optimum doping content close to the solubility limit of $Sb^{5+}$ substitution for the $Sb^{4+}$ sites of $SnO_2$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.2
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• pp.263-274
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• 1996

Titanium dioxide ($TiO_{2}$) film has been widely used as anti-reflection coating for solar cells but not as masking oxide for metallisation and diffusion of impurities. In this paper we have investigated the properties of $TiO_{2}$ for possible incorporation into solar cell processing sequence. Thus the use of a spray deposition system to form the $TiO_{2}$ film and the characterisation of this film to ascertain its suitability to solar cell processing. The spray-on $TiO_{2}$ film was found to be resistant to all the chemicals used in conjunction with solar cell processing. The high temperature anealing (in oxygen ambient) of the spray-on $TiO_{2}$ film resulted in an increased refractive index, which indicated the growth of an underlying thin film of $SiO_{2}$ film for the passivation of silicon surface which would reduce the recombination activities of the fabricated device. Most importantly, the successful incorporation of the $TiO{2}$ film will lead to the reduction of the many high temperature processing steps of solar cell to only one.

• Progress in Superconductivity
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• v.7 no.1
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• pp.87-91
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• 2005

[ $YBa_{2}Cu_{3}O_{7-x}$ ] thin films were fabricated on $LaAlO_3$(100) substrate by TFA-MOD process. Yttrium-excess (0, 2.5, 5, 10, 15, 20 $at\%$) coating solution was prepared by adding extra amount of yttrium into a stoichiometric(Y:Ba:Cu=1:2:3) TFA precursor solution. Results are presented concerning the influence of excess yttrium additions on the microstructure development and superconducting properties of $YBa_{2}Cu_{3}O_{7-x}$ film. Large sized CuO particles was observed by SEM EDS investigation. The addition of excess yttrium affected little on $T_c$ of $YBa_{2}Cu_{3}O_{7-x}$ film. $J_c$ of YBCO film was enhanced with excess yttrium addition. Jc maximum of $2.21\;MA/cm^2$ (77 K, self field) appeared with the $15\;at\%$ addition of excess yttrium. With further yttrium addition up to $20\;at\%$, Jc decreased down to $0.9\;MA/cm^2$.

• Journal of the Korean Ceramic Society
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• v.48 no.6
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• pp.487-492
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• 2011

The effect of the application of lanthanum strontrium manganite and yttria-stabilized zirconia (LSM-YSZ) nano-composite fabricated by pulsed laser deposition (PLD) as a cathode of solid oxide fuel cell (SOFC) is studied. A gradient-structure thin-film cathode composed of 1 micron-thick LSM-YSZ deposited at an ambient pressure ($P_{amb}$) of 200 mTorr; 2 micron-thick LSM-YSZ deposited at a $P_{amb}$ of 300 mTorr; and 2 micron-thick lanthanum strontium cobaltite (LSC) current collecting layer was fabricated on an anode-supported SOFC with an ~8 micron-thick YSZ electrolyte. In comparison with a 1 micron-thick nano-structure single-phase LSM cathode fabricated by PLD, it was obviously effective to increase triple phase boundaries (TPB) over the whole thickness of the cathode layer by employing the composite and increasing the physical thickness of the cathode. Both polarization and ohmic resistances of the cell were significantly reduced and the power output of the cell was improved by a factor of 1.6.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.397.1-397.1
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• 2014

최근 방사선 진단 영역에 이용되고 있는 증감지는 입사된 방사선의 감도를 증가시키기 위해 형광체를 사용하고 있으며, 외부의 에너지를 흡수하여 빛으로 방출하는 역할을 한다. 이는 방사선 검출기, 디스플레이, 의료기기 등 다양한 분야에 활용되고 있다. 필름에 X선을 노출 할 경우 형광체의 사용 유무에 따라 방사선 흡수 효율에 영향을 미치며, 이는 발광 효율 및 감도에 주요한 인자로 작용한다. 현재 상용화되어 있는 형광체는 낮은 발광 효율로 인한 한계를 가지므로, 발광 효율 향상을 위하여 제작 구조에 대한 연구가 진행되고 있다. 이 중 반사막을 활용하는 연구가 활발히 진행되고 있다. 일반적으로 형광체의 제조를 위하여 보편적으로 이용하고 있는 스크린프린팅 방법에서 건조 공정을 수행 시 균일도가 감소하는 현상이 발생한다. 이러한 현상은 반사막의 증착을 불균일하게 만드는 원인으로 작용하고 빛의 산란을 초래하는 현상을 초래한다. 이에 본 연구에서는 증착 시 투명도 저하에 따라 반사율이 증가되는 반사막 성질을 가지며, 방수성 및 절연성과 같은 보호층 특성을 지닌 유기성 투명 박막 페를린에 대하여 연구하고자 한다. 본 연구에서는 화학적 증기 증착법(Chemical Vapor Deposition, CVD)을 이용하여 투명 필름의 상단에 페를린을 코팅한 시편과 코팅하지 않은 시편으로 구분하여 제작하였고, 상단에 스크핀프린팅 방법을 활용하여 형광체를 도포 하였다. 시편 제작 후 실험은 시편을 필름 상단에 위치시키고, 일반진단에너지 대역(Model-SF 80)의 X선을 조사하였다. 이 후 현상기(model-pro14)를 통해 현상된 필름에 나타난 광학적 농도(Optical Density, O.D)를 농도계(Fluke Biomedical Nuclear Associates Densitometer)로 측정하였는데, 불확실성을 줄이기 위하여 총 5회를 측정하여 그 중 2번째로 높은 값을 도출하였다. 측정 결과, 페를린을 코팅한 형광체에서는 1.71의 O.D 값이 측정되었고, 페를린을 코팅하지 않은 형광체에서는 1.43의 O.D 값이 측정되었다. 이를 이용하여 투명도를 산출한 결과 상대적으로 약 1.76% 차이가 나타났다. 이러한 결과는 페를린 활용 시 환자의 피폭 선량 저감화 및 해상력 개선을 도모할 수 있을 것으로 사료된다.

• Progress in Superconductivity
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• v.8 no.1
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• pp.75-80
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• 2006

[ $Yb_2O_3$ ] films were successfully deposited on a cube-textured Ni and(100) $SrTiO_3$(STO) single crystal substrates by metal organic chemical vapor deposition(MOCVD) method using $H_2O$ vapor as an oxidant. $H_2O$ vapor was used in order to avoid the oxidation of Ni substrate. The working pressure and Ar flow rate were 10 Ton and 600 sccm, respectively. $Yb_2O_3$ films on STO were formed at high temperatures above $900^{\circ}C$. While XRD peaks from $Yb_2O_3$ were hardly detected at $900^{\circ}C$, the $Yb_2O_3$(400) texture was developed fur the films grown at deposition temperatures above $950^{\circ}C$. The AEM surface roughness of $Yb_2O_3$ film, grown on STO, was in the range of $6{\sim}10nm$ for the film deposited at $950^{\circ}C$ with a $H_2O$ vapor partial pressure of 5.5 Ton and deposition times of 3 and 5 mins. For cube-textured Ni substrate, both $Yb_2O_3$(222) and $Yb_2O_3$ (400) textures were developed textures at deposition temperatures above $850^{\circ}C$.

• Progress in Superconductivity
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• v.8 no.1
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• pp.87-92
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• 2006

The effects of Ba and Ce addition has been investigated in YBCO prepared by trifluoroacetate(TFA) metalorganic depostition(MOD) method. Precursor solutions with cation ratios of Y:Ba:Cu:Ce=1:2+x:3:x(x=0, 0.05, 0.1 and 1.5) have been prepared by adding an excess amount of cerium and barium. Coated film was calcined at lower temperature under a moisture-containing oxygen atmosphere. Superconducting YBCO films have been obtained by performing conversion heat treatment at temperature of $780{\sim}810^{\circ}C$ under a moisture-containing Ar(1,000 ppm oxygen) atmosphere. It has been shown that the critical current($I_c$) of YBCO film was degraded by doping of Ba and Ce atoms. But $I_c$ was increased as the amount of doped Ba and Ce content increased from 5% to 15 %. It was observed that there was little increase of a flux pinning force with Ba and Ce addition in YBCO film prepared by TFA-MOD process.

• Progress in Superconductivity
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• v.7 no.2
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• pp.140-144
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• 2006

We fabricated the YBCO films on single crystal $LaAlO_3$ substrates via a metal organic deposition (MOD) process. In the process, $Y_2Ba_1Cu_1O_x$ and $Ba_3Cu_5O_8$ powders were dissolved in trifluoroacetic acid (TFA) followed by calcining and firing heat treatments. To evaluate the effects of the firing temperature on YBCO phase formation and critical properties, the films were fired at $750^{\circ}C,\;775^{\circ}C\;and\;800^{\circ}C$ after calcining at $430^{\cric}C$. Microstructure observation indicated that a crack-free surface formed and a strong biaxial texture was developed. The FWHM of out-of-plane texture was measured to be in the range of $4.3^{\cric}-7.0^{\circ}$ for all the films. When the YBCO film was fired at $775^{\cric}C$, it had the highest critical properties: 88.5 K of critical temperature and 16 A/cm-width of critical current ($1MA/cm^2$ as critical current density). On the other hand, those properties were degraded as firing at $750^{\circ}C\;and\;800^{\circ}C$. It is considered that the improved critical values are partly owing to dense and homogeneous microstructure, strong texture, and high oxygen content.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.52.2-52.2
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• 2011

본 연구의 목적은 CIGS 태양전지의 두 가지 TCO층 중 AZO를 제외한 intrinsic ZnO의 전자빔 처리 영향에 대한 특성 분석을 하고자 함이다. 또한 추후 CIGS 태양전지를 제조하여 적용 시 전자빔 처리 전후의 특성이 어떻게 변하는지를 알아보기 위한 사전 실험이다. Intrinsic ZnO는 RF magnetron sputter 를 이용하여 약 100nm의 두께로 증착 하였다. 이때 공정 압력을 변수로 RF power는 80W로 설정 하였으며 Ar 분압은 10mtorr, 5mtorr, 1mtorr로 각각 달리 하며 증착 하였다. 이후 전자빔 처리를 위해 각각의 시편에 Argon flow 7sccm 상태에서 DC power 3kW, RF power 300W의 세기로 전자빔 처리를 실시 하였다. 전자빔 처리에 따른 전기적, 구조적 특성을 분석하기위해 Hall measurement와 SEM, XRD, UV-vis spectroscopy을 사용하였다. 먼저 Hall measurement 측정을 통한 전기적 분석 결과 비저항이 무한대에서 약 $40m{\Omega}{\cdot}cm$로 감소된 결과를 도출 할 수 있었으며, $2{\sim}3.4{\times}10^{18}/cm^3$ 이상의 carrier density 가 측정 되었다. UV-vis spectroscopy를 이용한 투과도 측정결과 모든 시편에서 Band gap이 감소하는 결과를 보였다. SEM, XRD를 이용한 분석결과 결정성 및 grain의 크기가 증가하는 결과를 얻을 수 있었다.