• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.306-307
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• 2015

유기태양전지의 대표적 Hole Transporting Layer(HTL)로는 전도성 고분자인 PEDOT:PSS이다. PEDOT:PSS는 약산성의 물질로 전극을 부식시켜 디바이스의 효율을 감소시키기 때문에 PEDOT:PSS를 대체하기 위한 Buffer층에 대한 연구가 활발히 진행되어지고 있다. PEDOT:PSS를 대체할 수 있는 Nickel Oxide(NiO) Buffer 층은 wide band-gab으로 Hole Transporting Layer와 Electron Blocking Layer 역할을 동시에 하여 디바이스의 효율을 향상시킬 수 있으며, 디바이스의 수명을 향상시킬 수 있다는 장점이 있다. NiO는 용액공정과 Sputter 증착 방법으로 형성할 수 있는데, 용액공정은 고온공정이 요구되어지고 Sputter 증착방법은 산화되기 쉬운 전극위에서는 전극의 손상을 발생한다. 본 연구에서는 이러한 단점을 해결하기 위해서 Ni을 Magnetron Sputter로 증착한 후 Ion Beam 처리를 통해 산화시켜 NiO 층을 형성하는 방법을 연구하였다. 본 연구에서 제안한 NiO형성 방법으로 유기태양전지를 제작하여 PEDOT:PSS를 Buffer층으로 사용한 태양전지와 Voc가 0.72 V로 유사하게 나와 NiO가 Buffer층으로 잘 형성된 것을 확인하였다.

• Progress in Superconductivity
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• v.7 no.2
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• pp.130-134
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• 2006

Buffer layers such as $CeO_2\;and\;Yb_2O_3$ films for YBCO coated conductors were deposited on (100) $SrTiO_3$ single crystals and (100) textured Ni substrates by a metal organic chemical vapor deposition (MOCVD) system of the hot-wall type. The substrates were moved with the velocity of 40 cm/hr. Source flow rate, $Ar/O_2$ flow rate and deposition temperature were main processing variables. The degree of film epitaxy and surface morphology were investigated using XRD and SEM, respectively. On a STO substrate, the $CeO_2$ film was well grown epitaxially above the deposition temperature of $450^{\circ}C$. However, on a Ni substrate, the XRD showed NiO (111) and (200) peaks due to Ni oxidation as well as (111) and (200) film growth. For the films deposited with $O_2$ gas as oxygen source, it was found that the NiO film was formed at the interface between the buffer layer and the Ni substrate. The NiO layer interrupts the epitaxial growth of the buffer layer. It seems that the epitaxial growth of the buffer layer on Ni metal substrates using $O_2$ gas is difficult. We are considering a new method avoiding Ni oxidation with $H_2O$ vapor instead of $O_2$ gas.

• Progress in Superconductivity
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• v.3 no.1
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• pp.125-129
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• 2001

NiO buffer layers were deposited on texture Ni tapes fur YBCO coated conductors by MOCVD(metal organic chemical vapor deposition) method, using a single solution source. Variables were deposition temperature and flow rate of $0_2$carrier gas. At higher temperatures, The NiO(111) texture was well developed, but the NiO(200) texture was developed at low temperatures. The best result was obtained at the deposition temperature of$ 470^{\circ}C$ and the gas flow rate of 200 sccm. FWHM value of $\omega$-scan fur NiO(200) of the film and $\Phi$-scan for NiO(111) of the film was $4.2^{\circ}$ and $7^{\circ}$, respectively.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.10a
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• pp.139-141
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• 2003

Multiple CeO$_2$/YSZ/Y$_2$O$_3$buffer layers, and subsequent YBCO films were deposited on the biaxially textured pure Ni and Ni ＋ 3at％W substrates using pulsed laser deposition. The deposition conditions of buffer layers on Ni and NiW were studied and compared. Good biaxial textures of buffer layers have been obtained on both substrates. The Jc's of YBCO films on these metal substrates were greater than 1$\times$10$^{6}$ A/$\textrm{cm}^2$ at 77K, 0T.

• 한국초전도학회:학술대회논문집
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• v.10
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• pp.56-60
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• 2000

Cube texture를 갖는 Ni기판위에 MOCVD(Metal Chemical Vapor Deposition)를 이용하여 NiO, CeO$_2$, YBCO 박막을 제조하였다. NiO(200)와 CeO$_2$(200) buffer layer는 450${\sim}$470$^{\circ}$C에서 10분간 MOCVD방법으로 (100)<001>Ni 기판위에 직접 증착하였다. 제조된 NiO, CeO$_2$ buffer layer는 조직이 치밀하며 표면의 상태가 매우 좋으며 Ni기판 위에 epitaxial하게 성장하였다. NiO는 Ni기판과 NiO<100>//Ni<100>의 방위관계를 가지고 성장하였으며, CeO$_2$는 증착조건에 따라 CeO$_2$ <100>//Ni<100> 및 CeO$_2$ <110>//Ni<100> 의 방위관계를 가지고 성장하였다. 증착된 NiO막과 CeO$_2$막에서 균열은 발생하지 않았다. MOCVD법으로 표면에 biaxial texture를 갖는 ceramic buffer를 증착시킨 NiO/Ni및 CeO$_2$/Ni 기판위에 YBCO박막을 MOCVD법으로 제조하였다. YBCO막은 기판온도 800$^{\circ}$C,증착압력 10torr, 산소분압을 0.7torr로 하여 10분간 행하였다. 공급원료의 조성에 따라 YBCO의 막의 texture와 형성되는 상이 변화되었다. NiO/Ni및 CeO$_2$/Ni 기판 위에 증착된 YBCO막은 c축 배향성을 가지고 성장하였으며, -scan 및 ${\varphi}$ -scan으로 측정한 (500)면의 in-plane과 (110)면의 out-of-plane의 FWHM(Full Width Half Maximum)값은 각각 10$^{\circ}$ 미만으로 우수하였다.

• Progress in Superconductivity
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• v.3 no.1
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• pp.95-98
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• 2001

Recently, NiO films have been studied as a buffer layer to fabricate the superconductor with preferred orientation and as a diffusion barrier to prevent the reaction between superconductor and textured nickel substrate . We fabricated NiO films on textured Ni substrate by thermal oxidation with various variables of temperature, oxidation time, atmosphere, and cooling rate. We investigated the alignment of NiO films by XRD and pole figure and the microstructures by SEM. (200) <001> alignment of NiO film was observed at the oxidation condition of $1200^{\circ}C$ far 10min and slow cooling in O2 atmosphere. During the process in Ar atmosphere, we could also observe the thermal faceting which affects the alignment of NiO alms on Ni substrate.

• Proceedings of the Korean Magnestics Society Conference
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• 1995.10a
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• pp.100-101
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• 1995

• Progress in Superconductivity and Cryogenics
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• v.6 no.2
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• pp.7-10
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• 2004

A study regarding the epitaxial growth of single $Y_2O_3$ buffer layer on biaxially textured Ni and NiW substrates using pulsed laser deposition is presented. Different deposition conditions were employed and compared in order to obtain good epitaxial $Y_2O_3$ film, furthermore importantly, to obtain good YBCO superconducting films. Following YBCO film deposited by PLD on the top of $Y_2O_3$ films have a good structure and superconducting properties. The J$_{c}$ of YBCO films on $Y_2O_3$ /Ni and $Y_2O_3$ /NiW were $1.0{\times}10^6 A/cm^2 and 1.1\times}10^6 A/cm^2$<.TEX> at 77K and self-field respectively, which indicated that $Y_2O_3$ is a suitable candidate as a single buffer layer for the fabrication of YBCO coated conductor.r.

• 한국초전도학회:학술대회논문집
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• v.11
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• pp.27-27
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• 2001

• Progress in Superconductivity and Cryogenics
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• v.8 no.4
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• pp.8-11
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• 2006

High temperature superconducting coated conductor has various buffer structures on Ni-W alloy. We comparatively studied the growth conditions of a multi buffer layer $(CeO_2/YSZ/CeO_2)$ and a single buffer layer$(CeO_2)$ on textured Ni-W alloy tapes. XRD data showed that the qualities of in-plane and out-of-plane textures of the two type buffer structures were good. Also, we investigated the properties of SmBCO superconducting layer that was deposited on the two type buffer structure. The SmBCO superconducting properties on the single and multi buffer structure showed different critical current values and surface morphologies. FWHM of In-plane and out-of-plane textures were $7.4^{\circ},\;5.0^{\circ}$ in the top CeO2 layer of the multi-buffer layers of $CeO_2/YSZ/CeO_2$, and $7.3^{\circ},\;5.1^{\circ}$ in the $CeO_2$ single buffer layer. $1{\mu}m-thick$ SmBCO superconducting layers were deposited on two type buffer layer. $I_c$ of SmBCO deposited on single and multi buffer were 90 A/cm, 150 A/cm and corresponding $J_c$ were $0.9MA/cm^2,\;1.5MA/cm^2$ at 77K in self-field, respectively.