• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.215-215
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• 2012

급속한 산업의 발달은 심각한 환경오염 및 에너지 문제를 가져왔다. 이를 해결하기 위한 방안으로 수소에너지에 대한 관심이 증가하고 있으며, 수소에너지를 생산하는 방법 중 하나로 태양에너지를 원천으로 하는 광촉매(photocatalyst)에 대한 연구가 점차적으로 증가하고 있는 추세이다. 현재 광촉매로 가장 많이 사용되는 $TiO_2$의 경우, 뛰어난 광활성과 저렴한 가격, 광 안정성, 화학적 안정성을 가짐에도 불구하고, 3.2 eV라는 넓은 band gap을 가지기 때문에 385 nm 이상의 긴 파장을 갖는 가시광선은 흡수할 수 없다. 또한, 광촉매 반응과정 중 recombination으로 인한 효율의 손실이 크기 때문에 이러한 문제들을 해결하기 위해 많은 연구가 진행되어 왔다. 본 연구에서는 ICP-assisted DC magnetron sputtering 방법을 이용하여 높은 결정성을 갖는 $TiO_2$ 박막을 제조하였다. 제작된 $TiO_2$ 박막은 높은 광촉매 특성을 나타냈으며, 또한 $TiO_2$의 anatase phase와 rutile phase의 bilayer structure를 통하여 recombination을 감소시킴으로써 높은 효율을 갖는 광촉매를 제작하였다. 박막의 chemical state와 crystallinity를 확인하기 위하여 X-ray photoelectron spectroscopy와 X-ray diffractometer를 이용하여 분석을 수행하였으며, 물 분해 장치(water splitting device)를 제작하여 수소와 산소 생성시 흐르는 전류를 측정하여 광촉매 특성을 평가하였다.

• Journal of Sensor Science and Technology
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• v.15 no.1
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• pp.65-70
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• 2006

Characteristics of thin-film NTC thermal sensors fabricated by micromachining technology were studied as a function of the thickness of membrane. The overall-structure of thermal sensor has a form of Au/Ti/NTC/$SiO_{X}$/(100)Si. NTC film of $Mn_{1.5}CoNi_{0.5}O_{4}$ with 0.5 mm in thickness was deposited on $SiO_{X}$ layer (1.2 mm) by PLD (pulsed laser deposition) and annealed at 873-1073 K in air for 1 hour. Au(200 nm)/Ti(100 nm) electrode was coated on NTC film by dc sputtering. By the results of microstructure, X-ray and NTC analysis, post-annealed NTC films at 973 K for 1 hour showed the best characteristics as NTC thermal sensing film. In order to reduce the thermal mass and thermal time constant of sensor, the sensing element was built-up on a thin membrane with the thickness of 20-65 mm. Sensors with thin sensing membrane showed the good detecting characteristics.

• Journal of Surface Science and Engineering
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• v.42 no.2
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• pp.73-78
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• 2009

Quinary Ti-Al-Si-C-N films were successfully synthesized on SUS 304 substrates and Si wafers by a hybrid coating system combining an arc ion plating technique and a DC reactive magnetron sputtering technique. In this work, the effect of Si content on the microstructure and mechanical properties of Ti-Al-C-N films were systematically investigated. It was revealed that the microstructure of Ti-Al-Si-C-N coatings changed from a columnar to a nano-composite by the Si addition. Due to the nanocomposite microstructure of Ti-Al-Si-C-N coatings, the microhardness of The Ti-Al-Si-C-N coatings significantly increased up to 56 GPa. In addition the average friction coefficients of Ti-Al-Si-C-N coatings were remarkably decreased with Si addition. Therefore, Ti-Al-Si-C-N coatings can be applicable as next-generation hard-coating materials due to their improved hybrid mechanical properties.

• Journal of the Korean Society for Heat Treatment
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• v.12 no.3
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• pp.199-205
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• 1999

The quaternary Ti-Al-V-N films have been grown on glass substrates by reactive dc and rf magnetron sputter deposition from a Ti-6Al-4V target in mixed Ar-$N_2$ discharges. The Ti-Al-V-N films were investigated by means of X-ray diffraction(XRD), electron probe microanalysis(EPMA) and scratch tester. Both XRD and EPMA results indicated that the Ti-Al-V-N films were of single B1 NaCl phase having columnar structure with the (111) preferred orientation. Scratch tester results showed that the adhesion strength of Ti-Al-V-N films which treated with substrate heating and vacuum annealing was superior to that of as-deposited film. The good adhesion strength was also achieved in the double-layer structure of Ti-Al-V-N/Ti-Al-V/Glass.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.304-304
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• 2014

Quaternary Ti-Al-Si-N films were deposited on WC-Co substrates by a hybrid deposition system of arc ion plating (AIP) method for Ti-Al source and DC magnetron sputtering technique for Si incorporation. The synthesized Ti-Al-Si-N films were revealed to be composites of solid-solution (Ti,Al)N crystallites and amorphous $Si_3N_4$ by instrumental analyses. The Si addition in Ti-Al-N films affected the refinement and uniform distribution of crystallites by percolation phenomenon of amorphous silicon nitride, similarly to Si effect in TiN film. As the Si content increased up to about 9 at.%, the hardness of Ti-Al-N film steeply increased from 30 GPa to about 50 GPa. The highest microhardness value (~50 GPa) was obtained from the Ti-Al-Si-N film having the Si content of 9 at.%, the microstructure of which was characterized by a nanocomposite of $nc-(Ti,Al)N/a-Si_3N_4$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.2
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• pp.75-79
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• 2015

Ti was deposited on the Al substrate using DC magnetron sputtering with changing the $N_2$ gas for the possible application of a solar absorbing layer. $N_2$ gas ranged from 50 to 75 sccm was systematically applied in the 5 sccm interval and the variation of the absorption rate was investigated. Microstructural examination and elemental analysis indicate that Ti was reacted with $N_2$ gas and formed $TiNO_x$ compound. As compared with the film without any exposure of $N_2$ gas, absorption rate improved by more than 20%. Typically the average absorption of $TiNO_x$ fim with 65% of $N_2$ gas was about 99% in the visible range, and the average absorption was more than 90% in the infrared absorption region respectively.

• Journal of Magnetics
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• v.18 no.4
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• pp.412-416
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• 2013

FePt:Ag (100 nm) nanocomposite thin films were prepared on naturally-oxidized Si substrates by dc magnetron sputtering at room temperature. X-ray diffraction (XRD) and transmission electron microscopy (TEM) are used to investigate the effects of annealing pressures on the ordering processes and microstructures of these films. The average sizes for the $L1_0$ ordered domains and the FePt grains are reduced to d = 9 nm and D = 13 nm from d = 19 nm and D = 34 nm, respectively, when the annealing pressure is enhanced to 0.6 GPa from room pressure at 873 K. Furthermore, the size distribution is improved into a narrow range. With increasing pressure, the coercivity of $L1_0$-FePt:Ag thin films decreases from 15.1 to 7.6 kOe. In the present study, the effects of high pressure on the $L1_0$ ordering processes and microstructures of FePt:Ag nanocomposite films were discussed.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.111.2-111.2
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• 2012

정보 기술 시대에 맞춰 광전소자의 연구가 활발해지면서 투명전극으로 사용될 수 있는 Transparent Conductive Oxide (TCO) 재료에 대한 관심이 높아지고 있다. 하지만 TCO의 대표적인 물질인 Indium Tin Oxide (ITO)의 경우 In의 가격 상승으로 인해 최근에는 낮은 전도도와 높은 투과도를 가질 수 있는 대체 물질에 대한 연구가 활발히 진행되고 있다. 그 중에서 3.2 eV 의 높은 밴드갭을 갖는 ZnO 는 가시광선 영역에서 높은 투과율을 나타낼 뿐만 아니라 Al, Ga을 도핑함으로써 낮은 전도도를 가질 수 있다. 이러한 TCO 재료는 surface texturing을 통하여 optical region 에서 반사를 억제 시킴으로서 빛을 모으는 역할을 하여 태양전지의 효율을 향상 시킬 수 있기 때문에 PV (Photovoltaics) Cell의 anti-reflective coating에 적용 할 수 있다. 본 연구에서는 pulsed DC magnetron sputtering을 이용하여 Ga-doped ZnO (GZO) 박막을 증착하였고, HCl 0.5 wt %로 wet etching을 통하여 surface texturing을 진행하였다. 결정성은 X-ray diffractometer (XRD)로 분석하였으며, 표면 형상은 Scanning Electron Microscope (SEM)을 통해 확인하였다. Van der Pauw 방법을 통해 resistivity, carrier concentration, hall mobility 등의 전기적 특성을 분석하였고 UV-Vis spectrophotometer 를 통해 투과도 및 반사도를 측정하였다.

• Journal of Magnetics
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• v.8 no.1
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• pp.32-35
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• 2003

Magnetic funnel Junctions (MTJs) were fabricated on thermally oxidized Si (100) wafers using DC magnetron sputtering. The film Structures were Ta(50 ${\AA}$)/CU(100 ${\AA}$)$Ni_{80}Fe_{20}(20 $ ${\AA}$)/Cu(50 ${\AA}$)/$Mn_{75}Ir_{25}(100 $ ${\AA}$)/$Co_{70}Fe_{30}(25$ ${\AA}$)/Al-O(15 ${\AA}$)/$Co_{70}Fe_{30}(25 $ ${\AA}$)/$Ni_{80}Fe_{20}(t)/Ta(50 $ ${\AA}$), with t=0 ${\AA}$, 100 and 1000 ${\AA}$, respectively. X-ray diffraction has shown improvement of (111) texture of IrMn$_3$ and Cu by annealing. The exchange-biased energy is almost inversely proportional to temperature. The difference between the coercivity H$_c$ and the exchange biased field H$_E$ for t = 0 $_3$ sample is smaller than that for t = 1000 ${\AA}$. For the pinned layer, the decreasing rate of the coercivity with the temperature is higher compared to that of the exchange field, but variation of H$_c$ is similar to that of the exchange field for free layer.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.328-328
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• 2013

본 연구에서는 선형 대향 타겟 스퍼터 시스템을 이용하여 Hetero sputtering 방법으로 증착한 AlGaZnO (AGZO) 박막의 두께에 따른 특성을 연구하였다. DC Power 250 W, Working pressure 0.3 mTorr, Ar 20 sccm의 고정된 성막 조건하에서, AGZO 박막의 두께가 25 nm에서 1 um로 증가함에 따른 전기적, 광학적, 구조적, 표면 특성을 Hall measurement, UV/visible spectrometry, Ellipsometry, XRD, FESEM 분석을 통해 분석하고 이를 설명할 수 있는 메커니즘을 제시하였다. 선형 대향 타겟 스퍼터의 장점으로 인해 상온에서도 우수한 특성을 갖는 AGZO 박막을 성장 시킬 수 있었으며 AGZO 박막의 전기적, 광학적특성은 다른 산화물 투명 전극 박막과 마찬가지로 두께에 매우 큰 영향을 받는 것을 알 수 있었다. 이러한 두께에 따른 특성 변화는 상온에서도 Columnar 구조를 가지는 AGZO의 구조적 특성과 밀접한 연관이 있으며 특히 결정립 크기가 AGZO의 광학적, 전기적 특성에 큰 영향을 미침을 XRD 분석을 통해 확인하였다. 또한 AGZO 두께에 따른 결정성의 차이가 박막의 n값에도 영향을 미침을 엘립소미터 분석을 통해 확인할 수 있었다. Scherrer formula을 활용하여 계산한 결과 AGZO 박막의 두께 증가에 따라 결정성 향상 및 결정립의 크기가 증가함을 알 수 있었으며, 이는 FESEM 분석을 통해서도 확인할 수 있었다.