• 한국결정학회지
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• 제12권3호
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• pp.171-176
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• 2001

(100), (111), (211)CdZnTe 기판 및 (100)GaAs 기판위에 HgCdTe 박막을 MOVPE 법으로 성장하였다. 기판의 방위에 따라 성장된 박막의 표면형상, 전기적 특성, 결정성 및 조성의 변화를 분석하였다. (111) CdZnTe 기판 위에서는 3차원적인 facet 형태의 성장이 일어났다. (100) CdZnTe 기판 위에 성장된 HgCdTe 박막의 경우 DCX반치폭은 55arcsec 정도로 125 arcsec의 반치폭을 보인 (100) GaAs에 비하여 우수한 결정성을 나타내었다. 그러나 전기적인 특성은 GaAs 기판의 경우, 이동도가 높은 n-형 전도성을 보였으나 CdZnTe 기판을 사용한 경우에는 10/sup 16/㎤ 이상의 운반자 농도를 갖는 p-형 전도성을 나타내었다.

• 반도체디스플레이기술학회지
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• 제9권1호
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• pp.29-33
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• 2010

Recently, the growth of ZnO thin film on glass substrate has been investigated extensively for transparent thin film transistor. We have studied the phase transition of ZnO thin films from metal to semiconductor by changing RF power in the deposition process by RF magnetron sputtering system. The structural, electric, and optical properties of the ZnO thin films were investigated. The film deposited with 75 watt of RF power showed n-type semiconductor characteristic having suitable resistivity $-3.56\;{\times}\;10^{+1}\;{\Omega}cm$, carrier concentration $-2.8\;{\times}\;10^{17}\;cm^{-3}$, and mobility $-0.613\;cm^2V^{-1}s^{-1}$ while other films by 25, 50, 100 watt of RF power closed to metallic films. From the surface analysis (AFM), the number of crystal grain of ZnO thin film increased as RF power increased. The transmittance of the film was over 88% in the visible region regardless of the change in RF power.

• 보존과학연구
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• 통권30호
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• pp.189-202
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• 2009

Ceramics from Taean shipwreck were studied to investigate the deterioration by soluble salts and desalination pattern according to each ceramic characterization. NaCl crystals were found as a crystal growth on the ceramic microstructure and deteriorated to push off the glaze layer of some Puncheong ware sample. As a result of monitoring the desalination pattern of ceramics for 74days, the earthenware sample with big pores and no glaze removed soluble salts so fast, but Puncheong ware and Whiteware samples removed lots of soluble salts slowly and continuously. Generally, it takes long time to remove soluble salts from porcelains, due to small pores and glaze, but the long-term desalination probably can cause the damage on the surface layer such like glaze. As some soluble salts still remains in the ceramic microstructures after desalination, it is very important to control and keep the relative humidity stable through the proper storage. There are various ceramic deterioration patterns by soluble salts. Therefore, it needs to select the desalination method of ceramics from shipwreck, considering the material characteristics and the production techniques.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 학술대회 논문집
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• pp.88-91
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• 2003

The crystal structure and properties of YBa$_2$Cu$_3$$O_{7-x}$(YBCO) and CeO$_2$ thin films deposited on r-plane (1(equation omitted)02) sapphire substrate by pulsed- laser deposition(PLD) have been investigated. C-axis oriented epitaxial YBCO thin films with critical temperature (Tc) of 88 K were routinely grown on (200) oriented CeO$_2$ buffer layers with thickness in the range between 20 to 80 nm. When the thickness of the (200)oriented CeO$_2$ buffer layer increases over than 80 nm, the superconducting properties of YBCO thin films on that were deteriorated. The decrease in Tc of YBCO thin films was explained by the microcrack formation in CeO$_2$ buffer layer. These results indicate that the thickness of the (200) oriented CeO$_2$ buffer layer is critical to the epitaxial YBCO thin nim growth on r-plane (1(equation omitted)02) sapphire substrate.e.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 춘계학술대회 논문집
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• pp.135-139
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• 2005

Thin films of $BaTiO_3$ system were prepared by radio frequency(rf)/dc magnetron sputtering method. We have investigated crystal structure, surface morphology and PTCR(positive-temperature coefficient of resistance) characteristics of the specimen depending on second heat-treatment temperatures. Second heat treatments of the specimen were performed in the temperature range of 400 to $1350^{\circ}C$. X-ray diffraction patterns of $BaTiO_3$ thin films show that the specimen heat treated below $600^{\circ}C$ is an amorphous phase and the one heat treated above $1100^{\circ}C$ forms a poly-crystallization. In the specimen heat-treated at $1300^{\circ}C$, a lattice constant ratio (c/a) was 1.188. Scanning electron microscope(SEM) image of $BaTiO_3$ thin films of the specimen heat treated in between 900 and $1100^{\circ}C}$ shows a grain growth. At $1100^{\circ}C$, the specimen stops grain-growing and becomes a poly-crystallization.

• 한국세라믹학회지
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• 제53권6호
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• pp.670-675
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• 2016

Calcium phosphate crystallites were prepared by wet chemical method for use in artificial bone. In order to obtain ${\beta}$-tricalcium phosphate (TCP), nano-crystalline calcium phosphate (CaP) was precipitated at $37^{\circ}C$ and at $pH5.0{\pm}0.1$ under stirring using highly active $Ca(OH)_2$ in DI water and an aqueous solution of $H_3PO_4$. The precipitated nano-crystalline CaP solution was kept at $90^{\circ}C$ for the growth of CaP crystallites. Through the growing process of CaP crystallites, we were able to obtain various sizes of rectangular CaP crystallites according to the crystal growing times. Dry nano-crystalline CaP powders at $37^{\circ}C$ were mixed with dry macro-crystalline CaP crystallites and the shaped mixture sample was fired at $1150^{\circ}C$ to make a ${\beta}-TCP$ block. Several tens of nm powders were uniformly coated on the surface, which was comprised of powders of several tens of ${\mu}m$, using a vibrator. The mixing ratio between the nanometer powders and the micrometer powders greatly affected the mechanical strength of the mixture block; the most appropriate ratio of these two materials was 50 wt% to 50 wt%. The sintered block showed improved mechanical strength, which was caused by the solid state interaction between the nano-crystalline ${\beta}-TCP$ and the macro-crystalline ${\beta}-TCP$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.395-396
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• 2008

Copper-Phthalocyanine (Cu-Pc) thin films of 100nm thickness have been deposited on silicon substrates as the different heating temperatures by thermal evaporation deposition technique. X-ray patterns showed with different temperature conditions at the $2\theta$ range of 5-$55^{\circ}$. The surface roughness of Cu-Pc thin films was investigated by using an atomic force microscope (AFM). A scanning electron microscope (SEM) has been used to characterize the micro-structures and morphologies depended on the substrate temperatures.

• 한국전기전자재료학회논문지
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• 제11권7호
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• pp.527-534
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• 1998

Thin film deposition of InN, which is a less-studied III-nitride compound semiconductor because of the difficulty if crystal growth, was performed by rf reactive sputtering method using In target and $N_2$reactive gas. The structrual, electrical, and optical properties of the produced films were measured and disussed according to the sputtering parameters such as deposition pressure, rf power, and substrate temperature. From the result of deposition pressure, rf power, and substrate temperature, we could obtain optimal conditions of 5m Torr, 60W, $60^{\circ}C$ for preparing InN thin film with high crystallinity, low carrier concentration, and high Hall mobility. The carrier concentration, Hall mobility, and optical bandgap of the fabricated InN thin films at optimal condition were $6.242\times10^{18}cm^{-3}, 212.526cm^2/V\cdot$ｓ, and 1.912eV, respectively.

• 한국자기학회지
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• 제9권5호
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• pp.256-262
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• 1999

DC/RF magnetron sputtering system을 이용하여 CoCr 박막 및 CoCrMo 박막의 Si 하지층의 도입에 따른 자기적 특성 및 미세구조의 변화에 대해 살펴보았다. 박막의 자기적 특성을 VSM을 통하여 측정한 결과, 고온에서 증착된 CoCrMo/Si 박막의 경우가 CoCr/Si 박막과는 달리 Si 하지층의 두께가 증가할수록 수직보자력값이 증가하는 것을 알 수 있었으며 AFM과 SEM을 이용한 surface morphology의 변화를 통하여 결정립 미세화와 균일화가 수직보자력을 증진시킴을 알 수 있었다. 또한, 박막의 결정배향성 및 미세구조를 XRD와 SEM을 통하여 관찰한 결과, CoCrMo/Si 박막의 (0002)우선 배향성이 CoCr/Si 박막의 (0002) 우선 배향성보다 상당히 크게 증진된 것을 볼 수 있었으며, SEM의 단면 측정을 통하여 CoCrMo/Si 박막과 CoCr/Si 박막의 기판 표면에서 성장하는 columnar 구조의 발달을 잘 관찰할 수 있었다.

• 한국재료학회지
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• 제12권5호
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• pp.387-390
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• 2002

A new approach of using double buffer layers of AlN and GaN for growth of GaN films on Si has been undertaken via molecular beam epitaxy using ammonia. The first buffers layer of AlN was grown using $N_2$plasma and the second of GaN was grown using ammonia. The surface roughness of the grown films was investigated by atomic force microscope and was compared with the normally grown films on sapphire. Double crystal x-ray rocking curve and low temperature photoluminescence techniques were employed for structural and optical properties examination. Donor bound exciton peak at 3.481 eV with full width half maximum of 41 meV was observed at 13K.