• Journal of the Korean institute of surface engineering
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• v.51 no.6
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• pp.365-371
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• 2018

1D core-shell nanostructures have attracted great attention due to their enhanced physical and chemical properties. Specifically, oriented single-crystalline $TiO_2$ nanorods or nanowires on a transparent conductive substrate would be more desirable as the building core backbone. However, a facile approach to produce such structure-based hybrids is highly demanded. In this study, a three-step hydrothermal method was developed to grow NiMn-layered double hydroxide-decorated $TiO_2$/carbon core-shell nanorod arrays on transparent conductive fluorine-doped tin oxide (FTO) substrates. XRD, SEM, TEM, XPS and Raman were used to analyze the obtained samples. The in-situ fabricated hybrid nanostructured materials are expected to be applicable for photoelectrode working in water splitting.

• Journal of The Geomorphological Association of Korea
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• v.25 no.4
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• pp.77-88
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• 2018

Wetlandsis developing on the lava plateau in Eundae-ri, even though there are no majorstreams into this area. As a result of drilling, 1~2m clay layer is founded under the superficial formations of the wetland, which are the main reasons for formation of the wetlands by limiting vertical drainage. The clay layer's Granulometry/XRD show very different characteristics from in situ weathering of basalt, and since 2~3cm of sand layer exist within the profile, the clay layer seems to be supplied and deposited from outside through surface/sheet flows. To keep the wetlands sustainably, the supply of water into the wetlands has to be increased by restoring the surface/sheet flow which is limited or deformed by pavement road.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.199-202
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• 2008

In this study, we investigated the thermal properties of $Zr_{66.4}Nb_{6.4}Cu_{10.5}Ni_{8.7}Al_{8.0}$ by using a differential scanning calorimeter (DSC), and then analyzed the composition of dendrite phase by using X-ray diffraction (XRD). A series of uniaxial compression tests has been performed under the strain rates between $10^{-5}/s$ and $10^{-2}/s$ at room temperature and near SLR. This BMGC has higher high temperature strength than other Zr-based monolithic BMGs because in-situ formed crystalline phases hinder a feasible viscous flow of amorphous matrix. Warm formability is also estimated by laboratory-scale extrusion test within supercooled liquid region. It was found that BMGC has poor formability compared with nother Zr-based bulk metallic glass composite presumably due to large volume fraction of 'brittle' crystalline phases distributed within amorphous matrix.

• Proceedings of the IEEK Conference
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• 2004.06b
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• pp.363-366
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• 2004

PZT thin films were formed by rf-magnetron sputtering on $Pt/Ti/SiO_2/Si$ substrate. Bulk PZT target containing $5\%$ excess PbO was used. They were formed with in-situ process at $650^{\circ}C$ as total thickness of 175 and 250 nm after the depositing of thin PZT films at room temperature, i. e. 2-step Sputtering. It was found that the ferroelectric perovskite phase is formed at $650^{\circ}C$ by XRD and the interface between room temp.-layer and $650^{\circ}C$ -layer is not existent. In the samples undergoing 2-step sputtering the dielectric constant was 600 or more and the leakage current density was $2{\times}10^{-7}A/cm^2$. So, we found that the room temp.-layer on the bottom electrode stabilize the underlaid layers.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.683-683
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• 2013

박막태양전지의 일종인 CIGS 태양전지는 직접천이형 반도체로 광흡수계수가 $1{\times}10^5cm^{-1}$로 매우 높고, 전기광학적 안정성이 우수하여 실리콘 결정질 태양전지를 대체할 고효율 태양전지로 각광받고 있다. CIGS 태양전지는 광흡수층 공정방법에 따라 다양한 결정구조 및 효율 차이가 나타난다. 본 실험에서는 Sputtering방법으로 금속전구체를 증착하고, Sequential process를 이용하여 고온에서 셀렌화 열처리를 수행하였다. Soda-lime glass 기판에 배면전극으로 Mo를 증착하고, 1단계로 CuIn0.7Ga0.3 조성비의 타겟을 이용하여 Sputtering법으로 $1.0{\sim}1.2{\mu}m$두께의 CIG 전구체를 증착하였다. 2단계로 CIG 전구체에 분자빔증착기를 이용하여 Se를 증착하고, 열처리를 통하여 CIGS 화합물 구조의 박막을 형성시켰다.증착된 CIGS 박막은 광전자분광분석기로 원소의 화학적 결합상태를 확인하고, in-situ 엑스선회절분석을 통해 Se층의 증착두께와 열처리 온도 변화에 따른 CIGS 층의 결정구조 및 결정화도 변화를 분석하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.666-666
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• 2013

CIGS solar cell에서 p-type semiconductor역할을 수행하는 Cu(In,Ga)Se로 이루어진 Absorber layer는 4 element multi binary compound로 stoichiometry 측면에서 다양한 형태가 나타나기 때문에 태양전지 효율을 향상시키기 위해 이에 대한 연구가 활발하다. 우리는 E-beam evaporation 방법으로 다양한 조건의 multi layer로 증착된 CIG layer 위에 일정 두께의 Se을 증착하면서 열처리 조건에 따른 Selenization 메커니즘에 대한 연구를 수행하였다. 결과분석을 위해(in-situ High Temperature) XRD, XPS, Micro Raman spectroscopy, FE-SEM, (Nano Indentor, Atomic Force Microscopy) 등을 이용하여 결정구조, 결정화도, Depth profile, Eg (band gap energy) 등을 알아보고 분석결과간의 상관관계를 고찰하였다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.9
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• pp.725-728
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• 2000

Ferroelectric thin film capacitors with high dielectric constant are important for the application of memory devices. In this work, We have systematically investigated the variation of grain sizes depending on the process condition of two-step process. Both in-situ annealing and ex-annealing have been compared depending on the annealing time. C-V measurement, ferroelectric properties, leakage current, XRD and SEM were performed to investigate the electircal properties and microstructural properties of Pb(La, Ti)O$_3$ films.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.5
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• pp.808-815
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• 2008

The composites were fabricated 61[vol.%] ${\beta}$-SiC and 39[vol.%] $TiB_2$ powders with the liquid forming additives of 8, 12, 16[wt%] $Al_2O_3+Y_2O_3$ as a sintering aid by pressureless annealing at 1650[$^{\circ}C$] for 4 hours. The present study investigated the influence of the content of $Al_2O_3+Y_2O_3$ sintering additives on the microstructure, mechanical and electrical properties of the pressureless annealed SiC-$TiB_2$ electroconductive ceramic composites. Reactions between SiC and transition metal $TiB_2$ were not observed in the microstructure and the phase analysis of the pressureless annealed SiC-$TiB_2$ electroconductive ceramic composites. Phase analysis of SiC-$TiB_2$ composites by XRD revealed mostly of ${\alpha}$-SiC(6H), ${\beta}$-SiC(3C), $TiB_2$, and In Situ YAG($Al_2Y_3O_{12}$). The relative density of SiC-$TiB_2$ composites was lowered due to gaseous products of the result of reaction between SiC and $Al_2O_3+Y_2O_3$. There is another reason which pressureless annealed temperature 1650[$^{\circ}C$] is lower $300{\sim}450[^{\circ}C]$ than applied pressure sintering temperature $1950{\sim}2100[^{\circ}C]$. The relative density, the flexural strength, the Young's modulus and the Vicker's hardness showed the highest value of 82.29[%], 189.5[Mpa], 54.60[Gpa] and 2.84[Gpa] for SiC-$TiB_2$ composites added with 16[wt%] $Al_2O_3+Y_2O_3$ additives at room temperature. Abnormal grain growth takes place during phase transformation from ${\beta}$-SiC into ${\alpha}$-SiC was correlated with In Situ YAG phase by reaction between $Al_2O_3$ and $Y_2O_3$ additive during sintering. The electrical resistivity showed the lowest value of 0.0117[${\Omega}{\cdot}cm$] for 16[wt%] $Al_2O_3+Y_2O_3$ additives at 25[$^{\circ}C$]. The electrical resistivity was all negative temperature coefficient resistance (NTCR) in the temperature ranges from $25^{\circ}C$ to 700[$^{\circ}C$]. The resistance temperature coefficient of composite showed the lowest value of $-2.3{\times}10^{-3}[^{\circ}C]^{-1}$ for 16[wt%] additives in the temperature ranges from 25[$^{\circ}C$] to 100[$^{\circ}C$].

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.05a
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• pp.26-30
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• 1995

We describe the preparation and characterization of epitaxial thin films made with high temperature superconductor, $YBa_2Cu_3O_{7-\delta}$. The influence of processing parameters for YBCO thin films on MgO substrates in-situ grown by the pulsed laser deposition, including parameters of a laser beam energy, oxygen pressure, substrate temperature, target-substrate dis-tance is discussed. The characteristics of YBCO thin films were analyzed by using XRD, R-T measurement, AFM, crosssectional TEM, and RBS. For examples of microwave device applications, The fabrication and characterization of the microstrip lowpass filter and bandpass filter are also presented.

• Journal of the Korean Vacuum Society
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• v.4 no.3
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• pp.319-326
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• 1995

초고진공에서 Si(100)-2X1 기판 위에 Pt를 약 100$\AA$의 두께로 증착한 후 in-situ로 열처리하는 고상에피택셜 성장법으로 PtSi 박막을 형성시켰다. XRD와 XPS 분석 결과 $200^{\circ}C$로 열처리한 시료에서는 Pt3Si, Pt2Si와 PtSi의 상이 섞여 있었으나 50$0^{\circ}C$로 열처리한 시료에서는 PtSi의 단일상만 확인되었으며, 형성된 PtSi 박막은 주상구조와 판상구조의 이중구조를 나타내었다. 기판 온도를 $500^{\circ}C$로 유지하면서 Pt를 증착한 후 $750^{\circ}C$에서 열처리한 경우에는 판상구조를 갖는 양질의 PtSi 박막이 에피택셜 성장되었다. HRTEM분석 결과 에피텍셜 성장된 PtSi와 기판 Si(100)의 계면은 PtSi[110]//Si[110], ptSi(110)//Si(100)의 정합성을 가졌다. 판상구조를 갖는 PtSi상의 에피택셜 방향은 기판과 열처리 온도에는 의존하나 열처리 시간에는 무관한 것으로 나타났다.