• 한국진공학회지
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• 제19권1호
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• pp.52-57
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• 2010

$BiFeO_3(BFO)/Pb(Zr_{0.52}Ti_{0.48})O_3$(PZT) bilayer와 multilayer의 다층구조를 만들어 전기적 특성을 측정하여 같은 두께의 BFO 단층박막과 비교해 보았다. BFO와 PZT 용액을 이용하였으며 chemical solution deposition 방법으로 Pt/Ti/$SiO_2$/Si(100) 기판위에 각 박막을 증착하였다. X-ray diffraction 분석을 통해 모든 박막이 다배향(multi-orientation) 페로브스카이트 (perovskite) 구조를 가졌음을 확인하였다. BFO/PZT Bilayer와 multilayer 박막들은 BFO 단층박막의 비해 누설전류 값이 500 kV/cm에서 약 4, 5차수 정도 감소했으며, 이로 인해 BFO/PZT 다층박막의 강유전체 특성이 크게 향상되었다. BFO/PZT multilayer 다층구조 박막의 경우 안정된 이력곡선(hysteresis loop)을 나타냈으며, 잔류 분극(remanent polarization)의 값은 $44.3{\mu}C/cm^2$이었으며, 항전계($2E_c$) 값은 681.4 kV/cm였다.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 1999년도 Proceedings of Pre-symposium of the 10th ISWPC
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• pp.204-208
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• 1999

Friction was measured on filter paper sheets impregnated with model compounds representing wood extractives using an apparatus based on the horizontal plane principle. The best lubrication of paper surfaces was achieved when they were completely separated by a densely packed film of saturated long-chain amphophilic molecules, such as fatty acids. The fatty acids adsorbed with their polar ends on the paper surface, causing their hydrocarbon chaine to be orientated perpendicularly to the paper surface. The saturated C18-acid, stearic acid, was an efficient lubricator for paper surfaces. The introduction of a double bond in stearic acid eliminated its lubricating ability. The spatial length of the lubricating fatty acid thereby decreases from 24${\AA}$ to 11${\AA}$. However the transisomer of oleic acid, elidic acid, had the ability to lower friction due to an increased spatial length of the fatty acid. Both the spatial length of the hydrocarbon chain and the number of lubricating chains may be of importance for the paper-to-paper friction caused by wood extractives. A hydrophilic head-graup in the wood extractive and an ordered molecular layer of lubricating molecules seems also to be prerequisites for efficient lubrication. A chemical weak boundary layer between the paper sheets was suggested to cause the low friction when long chain saturated fatty acids were deposited on paper.

• 한국재료학회지
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• 제4권2호
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• pp.136-142
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• 1994

초청장 Si(111)기탄상에 초고진공 챔버에서 Ti을 증착하여 $TiSi_{2}$를 에피층으로 성장시켰다. 재구성된 (reconstructed) Di(111)표면에 상온에서 50$\AA$ 두께의 Ti을 증착한 후 $100^{\circ}C$간격으로 $800^{\circ}C$까지 열처리 하였다. $TiSi_{2}$박막의 구조는 전자회절 패턴 분석을 통하여 준안정상인 C49상임을 확인하였다. SEM 사진은 세가지 형태의 island를 보이고 있다. 각 island 는 단결정이며 그 구조는 서로 다른 결정학적 방향을 갖는 에피구조이다. 이러한 TiSi$_{2}$ island[112]C49 TiSi$_{2}$/[110]Si, (021) C49 $TiSi_{2}$/(111)Si의 방향관계를 가지고 있다.

• 소성∙가공
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• 제28권1호
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• pp.43-48
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• 2019

Aluminum nitride (AlN) is used by the semiconductor industry, and is a compound that is required when manufacturing high thermal conductivity. The AlN films with c-axis orientation and thermal conductivity characteristic were deposited by using the Pulsed Laser Deposition (PLD). The AlN thin films were characterized by changing the deposition conditions. In particular, we have researched the AlN thin film deposited under optimal conditions for growth atmosphere. The epitaxial AlN films were grown on sapphire ($c-Al_2O_3$) single crystals by PLD with AlN target. The AlN films were deposited at a fixed temperature of $650^{\circ}C$, while conditions of nitrogen ($N_2$) pressure were varied between 0.1 mTorr and 10 mTorr. The quality of the AlN films was found to depend strongly on the $N_2$ partial pressure that was exerted during deposition. The X-ray diffraction studies revealed that the integrated intensity of the AlN (002) peak increases as a function the corresponding Full width at half maximum (FWHM) values decreases with lowering of the nitrogen partial pressure. We found that highly c-axis orientated AlN films can be deposited at a substrate temperature of $650^{\circ}C$ and a base pressure of $2{\times}10^{-7}Torr$ in the $N_2$ partial pressure of 0.1 mTorr. Also, it is noted that as the $N_2$ partial pressure decreased, the thermal conductivity increased.