ZrVFe 다공체 표면오염층의 UVO₃ 크리닝 공정

김광배(Kwangbae Kim),김호준(Hojun Kim),진새라(Saera Jin),임예솔(Yesol Lim),이현준(Hyunjun Lee),김성훈(Seonghoon Kim),노윤영(Yunyoung Noh),송오성(Ohsung Song) 한국산학기술학회 2022 한국산학기술학회논문지 Vol.23 No.1

코발트실리사이드를 이용한 염료감응형 태양전지 상대전극의 신뢰성 평가

김광배(Kwangbae Kim),박태열(Taeyeul Park),송오성(Ohsung Song) 한국산학기술학회 2017 한국산학기술학회논문지 Vol.18 No.4

염료감응형 태양전지 촉매층으로 CoSi의 신뢰성을 확인하기 위해 전자빔증착기를 이용하여 100 ㎚-Co/300 ㎚-Si/quartz의 적층구조를 형성하고, 700℃-60분의 진공열처리하여 약 350 ㎚-CoSi를 형성하였다. 이때 잔류 Co를 제거하기 위해 80℃-30%의 황산처리를 진행하였다. 또한 비교를 위해 100 ㎚-Pt/glass 상대전극을 준비하였다. CoSi 상대전극이 채용된 DSSC 소자의 신뢰성을 확인하기 위해 80℃ 온도조건에서 0, 168, 336, 504, 672, 840시간동안 유지하였다. 이들을 채용한 DSSC 소자의 광전기적 특성을 분석하기 위해 solar simulator와 potentiostat을 이용하였다. CoSi 상대전극의 촉매활성도, 미세구조, 그리고 조성 분석을 확인하기 위해 CV, FE-SEM, FIB-SEM, EDS를 이용하여 분석하였다. 시간에 따른 에너지변환효율 결과, Pt와 CoSi 상대전극 모두 에너지변환효율이 504시간까지는 유지되다가 672시간 경과 후 처음의 50%로 감소하는 특성을 보였다. 촉매활성도 분석 결과, 시간이 지남에 따라 Pt와 CoSi 상대전극 모두 촉매활성도가 감소하여 각각 64%, 57%의 촉매활성도를 보였다. 미세구조 분석 결과, CoSi층은 전해질에 대한 안정성은 우수하였으나, 하부 쿼츠 기판과 CoSi층의 접촉면에 스트레스가 집중되어 국부적으로 크렉이 형성되며, 궁극적으로 ㎛급의 박리현상을 확인하였다. 따라서 CoSi 상대전극은 실리사이드화 되는 과정에서 잔류응력 때문에 열화가 일어나므로 신뢰성의 확보를 위해서는 이러한 잔류응력의 대책이 필요하였다. Cobalt silicide was used as a counter electrode in order to confirm its reliability in dye-sensitized solar cell (DSSC) devices. 100 ㎚-Co/300 ㎚-Si/quartz was formed by an evaporator and cobalt silicide was formed by vacuum heat treatment at 700℃ for 60 min to form approximately 350 ㎚-CoSi. This process was followed by etching in 80℃-30% H2SO4 to remove the cobalt residue on the cobalt silicide surface. Also, for the comparison against Pt, we prepared a 100 ㎚-Pt/glass counter electrode. Cobalt silicide was used for the counter electrode in order to confirm its reliability in DSSC devices and maintained for 0, 168, 336, 504, 672, and 840 hours at 80℃. The photovoltaic properties of the DSSCs employing cobalt silicide were confirmed by using a simulator and potentiostat. Cyclic-voltammetry, field emission scanning electron microscopy, focused ion beam scanning electron microscopy, and energy dispersive spectrometry analyses were used to confirm the catalytic activity, microstructure, and composition, respectively. The energy conversion efficiency (ECE) as a function of time and ECE of the DSSC with Pt and CoSi counter electrodes were maintained for 504 hours. However, after 672 hours, the ECEs decreased to a half of their initial values. The results of the catalytic activity analysis showed that the catalytic activities of the Pt and CoSi counter electrodes decreased to 64% and 57% of their initial values, respectively(after 840 hours). The microstructure analysis showed that the CoSi layer improved the durability in the electrolyte, but because the stress concentrates on the contact surface between the lower quartz substrate and the CoSi layer, cracks are formed locally and flaking occurs. Thus, deterioration occurs due to the residual stress built up during the silicidation of the CoSi counter electrode, so it is necessary to take measures against these residual stresses, in order to ensure the reliability of the electrode.

불활성 가스의 O₂와 CO 불순물 제거를 위한 Ni 촉매의 물성 평가

김광배(Kwangbae Kim),진새라(Saera Jin),김은석(Eunseok Kim),임예솔(Yesol Lim),이현준(Hyunjun Lee),김성훈(Seonghoon Kim),노윤영(Yunyoung Noh),송오성(Ohsung Song) 한국산학기술학회 2020 한국산학기술학회논문지 Vol.21 No.4

반도체 산업용 9N 이상의 초고순도 N₂, Ar 등 불활성 가스 제조를 위해 가스 정제공정에 사용되고 있는 Ni 촉매의 물성 평가 및 촉매적 특성을 확인하였다. 조성이 다른 원기둥 형태의 C1, 츄러스 형태의 C2의 두 가지 Ni 촉매에 대해 비교 평가를 진행하였다. Ni 촉매의 형상과 미세구조를 분석하기 위해 광학현미경과 FE-SEM을 이용하였으며, 조성 확인 및 물성을 분석하기 위해 EDS, XRD, 그리고 micro-Raman 분석을 이용하였다. 또한 Ni 촉매의 비표면적 및 촉매적 특성을 확인하기 위해 BET, Pulse Titration 분석을 진행하였다. 조성 분석결과, C1의 경우, 상대적으로 graphite가 불순물로 다량 포함되어 있는 것을 확인하였으며, C2는 C1에 비해 Ni의 함량이 높은 것을 확인하였다. 비표면적 분석 결과, C2의 비표면적이 C1보다 약 1.69배 정도 큰 것을 확인할 수 있었다. 촉매적 특성분석 결과, 상온에서 O₂와 CO 불순물 제거 정도가 C2가 우수함을 확인하였다. 따라서 반도체 산업용 초고순도 불활성 기체 제조를 위한 Ni 촉매로는 불순물이 적고, 비표면적이 크며, 상온에서 O₂와 CO 제거 성능이 우수한 C2가 적합함을 확인하였다. This study examined the catalytic property of Ni-catalyst used in the gas purifying process to manufacture inert gases of N2 and Ar with high-purity over 9N for semiconductor industrial applications. Two types of Ni-catalysts with a cylindrical shape (C1) and churros shape structure (C2) were compared for the assessment. Optical microscopy and FESEM were used to analyze the shape and microstructure of the Ni-catalyst. EDS, XRD, and micro-Raman characterization were performed to examine the composition and properties. BET and Pulse Titration analyses were conducted to check the surface area and catalytic property of the Ni-catalyst. From the composition analysis results, C1 contained a relatively large amount of graphite as an impurity, and C2 contained higher Ni contents than C1. From specific surface area analysis, the specific surface area of C2 was approximately 1.69 times larger than that of C1. From catalytic property analysis, outstanding performance in O₂ and CO impurity removal was observed at room temperature. Therefore, C2, having low-impurity and large specific surface area, is a suitable catalyst for the high-purity inert gas process in the semiconductor industry because of its outstanding performance in O₂ and CO impurity removal at room temperature.

불활성 가스의 O₂와 CO 불순물 제거를 위한 Ni 촉매의 물성 평가

김광배,진새라,김은석,임예솔,이현준,김성훈,노윤영,송오성,Kim, Kwangbae,Jin, Saera,Kim, Eunseok,Lim, Yesol,Lee, Hyunjun,Kim, Seonghoon,Noh, Yunyoung,Song, Ohsung 한국산학기술학회 2020 한국산학기술학회논문지 Vol.21 No.4

반도체 산업용 9N 이상의 초고순도 N₂, Ar 등 불활성 가스 제조를 위해 가스 정제공정에 사용되고 있는 Ni 촉매의 물성 평가 및 촉매적 특성을 확인하였다. 조성이 다른 원기둥 형태의 C1, 츄러스 형태의 C2의 두 가지 Ni 촉매에 대해 비교 평가를 진행하였다. Ni 촉매의 형상과 미세구조를 분석하기 위해 광학현미경과 FE-SEM을 이용하였으며, 조성 확인 및 물성을 분석하기 위해 EDS, XRD, 그리고 micro-Raman 분석을 이용하였다. 또한 Ni 촉매의 비표면적 및 촉매적 특성을 확인하기 위해 BET, Pulse Titration 분석을 진행하였다. 조성 분석결과, C1의 경우, 상대적으로 graphite가 불순물로 다량 포함되어 있는 것을 확인하였으며, C2는 C1에 비해 Ni의 함량이 높은 것을 확인하였다. 비표면적 분석 결과, C2의 비표면적이 C1보다 약 1.69배 정도 큰 것을 확인할 수 있었다. 촉매적 특성분석 결과, 상온에서 O₂와 CO 불순물 제거 정도가 C2가 우수함을 확인하였다. 따라서 반도체 산업용 초고순도 불활성 기체 제조를 위한 Ni 촉매로는 불순물이 적고, 비표면적이 크며, 상온에서 O₂와 CO 제거 성능이 우수한 C2가 적합함을 확인하였다. This study examined the catalytic property of Ni-catalyst used in the gas purifying process to manufacture inert gases of N2 and Ar with high-purity over 9N for semiconductor industrial applications. Two types of Ni-catalysts with a cylindrical shape (C1) and churros shape structure (C2) were compared for the assessment. Optical microscopy and FESEM were used to analyze the shape and microstructure of the Ni-catalyst. EDS, XRD, and micro-Raman characterization were performed to examine the composition and properties. BET and Pulse Titration analyses were conducted to check the surface area and catalytic property of the Ni-catalyst. From the composition analysis results, C1 contained a relatively large amount of graphite as an impurity, and C2 contained higher Ni contents than C1. From specific surface area analysis, the specific surface area of C2 was approximately 1.69 times larger than that of C1. From catalytic property analysis, outstanding performance in O₂ and CO impurity removal was observed at room temperature. Therefore, C2, having low-impurity and large specific surface area, is a suitable catalyst for the high-purity inert gas process in the semiconductor industry because of its outstanding performance in O₂ and CO impurity removal at room temperature.

염료감응형 태양전지용 코발트실리사이드들의 촉매 물성

김광배,노윤영,송오성,Kim, Kwangbae,Noh, Yunyoung,Song, Ohsung 한국재료학회 2016 한국재료학회지 Vol.26 No.8

The cobalt silicides were investigated for employment as a catalytic layer for a DSSC. Using an E-gun evaporation process, we prepared a sample of 100 nm-thick cobalt on a p-type Si (100) wafer. To form cobalt silicides, the samples were annealed at temperatures of $300^{\circ}C$, $500^{\circ}C$, and $700^{\circ}C$ for 30 minutes in a vacuum. Four-point probe, XRD, FE-SEM, and CV analyses were used to determine the sheet resistance, phase, microstructure, and catalytic activity of the cobalt silicides. To confirm the corrosion stability, we also checked the microstructure change of the cobalt silicides after dipping into iodide electrolyte. Through the sheet resistance and XRD results, we determined that $Co_2Si$, CoSi, and $CoSi_2$ were formed successfully by annealing at $300^{\circ}C$, $500^{\circ}C$, and $700^{\circ}C$, respectively. The microstructure analysis results showed that all the cobalt silicides were formed uniformly, and CoSi and $CoSi_2$ layers were very stable even after dipping in the iodide electrolyte. The CV result showed that CoSi and $CoSi_2$ exhibit catalytic activities 67 % and 54 % that of Pt. Our results for $Co_2Si$, CoSi, and $CoSi_2$ revealed that CoSi and $CoSi_2$ could be employed as catalyst for a DSSC.

PECVD를 이용한 DLC 두께 제어에 따른 간섭색 구현

박새봄,김광배,김호준,김치환,최현우,송오성,Park, Saebom,Kim, Kwangbae,Kim, Hojun,Kim, Chihwan,Choi, Hyun Woo,Song, Ohsung 한국재료학회 2021 한국재료학회지 Vol.31 No.7

Various surface colors are predicted and implemented using the interference color generated by controlling the thickness of nano-level diamond like carbon (DLC) thin film. Samples having thicknesses of up to 385 nm and various interference colors are prepared using a single crystal silicon (100) substrate with changing processing times at low temperature by plasma-enhanced chemical vapor deposition. The thickness, surface roughness, color, phases, and anti-scratch performance under each condition are analyzed using a scanning electron microscope, colorimeter, micro-Raman device, and scratch tester. Coating with the same uniformity as the surface roughness of the substrate is possible over the entire experimental thickness range, and more than five different colors are implemented at this time. The color matched with the color predicted by the model, assuming only the reflection mode of the thin film. All the DLC thin films show constant D/G peak fraction without significant change, and have anti-scratch values of about 19 N. The results indicate the possibility that nano-level DLC thin films with various interference colors can be applied to exterior materials of actual mobile devices.

코발트실리사이드 상대전극을 채용한 염료감응형 태양전지의 물성 연구

노윤영 ( Yunyoung Noh ),김광배 ( Kwangbae Kim ),송오성 ( Ohsung Song ) 대한금속재료학회(구 대한금속학회) 2017 대한금속·재료학회지 Vol.55 No.1

Cobalt silicide was used as a counter electrode to replace the Pt catalytic layer of a dye-sensitized solar cell (DSSC) device. 100 nm Si/ 100 nm Co on quartz were formed by sputtering, and cobalt-silicides were formed by vacuum heat treatment at 500 ℃ and 700 ℃ for 30 min, respectively. Field emission scanning electron microscopy (FE-SEM) was used to analyze the surface microstructure. X-ray diffraction (XRD) and Auger electron spectroscopy (AES) depth profiling analysis were used to confirm the phases. Also, cyclic-voltammetry (CV) analysis was employed to confirm the catalytic activity, and photovoltaic properties were confirmed using a simulator and potentiostat. The microstructure analysis indicated that the 500 ℃ and 700 ℃ silicidation led to a uniform planar layer, and island-like agglomerates, respectively. In the XRD and AES results, those phases were structures of quartz/CoSi/Co and quartz/dot-(CoSi₂/Co). CV analysis showed that Si/Co and CoSi/Co exhibited catalytic activity, while dot-(CoSi₂/Co) did not show catalytic activity due to the isolated dot structure. The energy conversion efficiencies of DSSCs with CoSi/Co and dot-(CoSi₂/Co) were 3.75% and 0%, respectively, while that of Pt employed DSSC was 5.13%. Our result implies that using the nano-thick CoSi as a reduction catalytic layer may be an effective replacement for Pt. (Received March 4, 2016; Acceted July 22, 2016)

작동전극부에 나노다이아몬드를 첨가한 염료감응형 태양전지의 물성 연구

노윤영 ( Yunyoung Noh ),김광배 ( Kwangbae Kim ),최민경 ( Minkyoung Choi ),송오성 ( Ohsung Song ) 대한금속재료학회(구 대한금속학회) 2016 대한금속·재료학회지 Vol.54 No.1

We prepared a TiO2 blocking layer containing 0~0.5 wt% nano diamonds (NDs) to increase the effective surface area of working electrodes in a dye sensitized solar cell (DSSC). The result was a DSSC with a 0.45 cm2 active area of a glass/FTO/blocking layer (TiO2 with NDs)/TiO2/dye/electrolyte/100 nm Pt/glass structure. The microstructure of the blocking layer was examined by optical microscope, FESEM, and AFM. UV-VIS-NIR was used to determine the optical absorbance of the working electrodes containing NDs. The photovoltaic properties for the ND added DSSC, such as short circuit current density, open circuit voltage, fill factor, energy conversion efficiency, and impedance, were checked using a solar simulator and potentiostat. Microstructure characterization showed that the NDs were evenly dispersed in the blocking layer. The absorbance in the visible light regime increased as the ND content increased. The photovoltaic properties indicated that energy conversion efficiency increased from 3.53% to 4.96% with 0 wt% and 0.4 wt% ND addition. This was due to the decreased interface resistance of the working electrode and the increased surface area and shunt resistance of the blocking layer resulting from the addition of the NDs. The DSSC with 0.5 wt% NDs was less efficient due to a reduction of the effective electron transport area caused by excess NDs. Our results suggest that we can improve the efficiency of a DSSC by proper addition of NDs into the blocking layer.

폴딩 기법을 이용한 스털링실버 링 제조 공정

김익규(Ik gyu Kim),김광배(Kwangbae Kim),김은석(Eun-Seok Kim),송오성(Ohsung Song) 한국산학기술학회 2019 한국산학기술학회논문지 Vol.20 No.9

스털링실버 판재를 콜드-다이 포징(cold-die forging)과 어닐링을 반복하는 폴딩공정을 이용하여 반지모양으로 가공하는 신공정을 제안하였다. 도넛모양으로 재단된 판재에 선폭 0.43 μm인 격자를 각인하였다. 그 후 경사가 45°, 60°, 75°인 다이(die)를 이용한 포징과 어닐링을 반복하여 폴딩하였다. 비교를 위해 어닐링을 생략한 시편 또한 준비하였다. 각인된 격자의 길이 변화를 측정하여, 공정과정에 따른 스트레인을 확인하였다. 버니어캘리퍼스, 비커스 경도 측정기(Vickers hardness tester)와 광학현미경, UV-VIS 컬러미터(colormeter)를 이용하여 크기, 경도, 미세구조, 표면색을 확인하였다. 어닐링을 생략하는 경우 크랙이 발생하였으나, 어닐링을 부가하는 경우 성공적으로 변형이 가능했다. 시편의 거시적인 스트레인을 분석한 결과, 최종공정 후 외경의 길이와 두께는 각각 감소하였지만, 내경의 길이와 폭은 각각 증가하였다. 시편의 미시적인 스트레인은 수평 방향에서 최대 +0.128 만큼 증가하였다. 비커스 경도의 경우, 열처리 시에는 감소하지만 폴딩공정 후에는 증가하는 경향을 나타내었다. 미세구조 관찰 결과 어닐링 직후 결정립의 크기가 증가하고 폴딩공정 직후는 감소하였다. Lab지수를 기준으로 색차는 모든 공정에서 10 이하로 확인되었다. 결국 도넛형태의 은 판재를 폴딩공정을 이용하여 성공적인 반지모양의 주얼리 제조가 가능하였다. A novel folding process is proposed using a repeated cold-die forging and annealing to form a sterling silver ring. Sterling silver plate was cut into a doughnut shape, and lattices with 0.43-mm line-width were imprinted on it. The sample was folded by forging using dies with slopes of 45°, 60°, and 75° and annealing. For comparison, samples were also fabricated without annealing. Strain was identified by measuring the length of lattices. Vernier calipers, a Vickers hardness tester, an optical microscope, and a UV-VIS colorimeter were used to determine the size, hardness, microstructure, and body color. Without annealing, cracks occurred. However, successful deformation was possible when annealing was used. The results of macro strain measurements show that the outer diameter and width decreased, while the inner diameter and thickness increased after the final process. The maximum strain was increased 0.128 toward the parallel direction. The Vickers hardness decreased after annealing and increased after the folding process. The microstructure results showed that the grain size increased after annealing but decreased after folding. The color difference based on the Lab index was under 10 for all processes. Eventually, a doughnut-shaped silver plate was successfully deformed into a ring shape by the folding process.

다공성 은의 폴리실록센 첨가에 따른 물성 변화

김은석(Eun-seok Kim),김익규(Ik-gyu Kim),김광배(Kwangbae Kim),송오성(Ohsung Song) 한국산학기술학회 2020 한국산학기술학회논문지 Vol.21 No.8

20 ㎛급 은 분말과 53 ㎛급 소금 30 wt%의 혼합체에 폴리실록센을 1∼4 wt%까지 첨가시키고 750℃-60min 소결하고, 소금을 선택적으로 녹여내어 액상 향수를 담지할 수 있는 다공체를 제작하였다. 소결전후에 폴리실록센 첨가량에 따라 기공, 경도, 그리고 미세구조의 변화를 확인하였다. 제작한 은 담지체는 소결 전후 모두 열린 기공으로 형성되고, 소결 후에는 지름 및 높이 방향으로 2∼7 % 수축하였다. 비커스 경도는 소결 후 모두 증가하였고, 특히 2 wt%의 폴리실록센을 첨가한 경우 소결 전보다 2배 증가하는 것을 확인하였다. 미세구조의 경우 폴리실록센 첨가에 따라 은담지체 표면상태는 어두워졌고, 기공이 50 ㎛에서 10 ㎛ 이하로 작아지는 것을 확인하였다. 조성분포 확인 결과 폴리실록센 2 wt% 첨가하였을 때 고루 분포되어 있었으며, 3 wt%이상 첨가하였을 때 뭉쳐져서 강도가 저하되는 문제가 있었다. 따라서 열린기공을 가진 다공성 은에 대해 주얼리 용도로 2 wt%의 적정량의 폴리실록센을 첨가하여 성공적인 강화가 가능하였다. A porous material which can contain liquid perfume was manufactured by adding 1∼4 wt% of polysiloxane into a composite containing 20 ㎛ Ag powder and 30 wt% of 53 ㎛ salt, sintering for 60 min at 750℃, and melting salt selectively. The changes in pore, hardness, and microstructure were confirmed according to the polysiloxane content both before and after sintering. The manufactured silver liquid container was formed with open pores both before and after sintering, and the container shrunk by 2∼7 % in both perpendicular and parallel directions after sintering. Vickers hardness was increased after sintering and was doubled when 2 wt% of polysiloxane was added. In case of the microstructure, the surface condition of the silver liquid container became darker according to the polysiloxane content, and the pore size was decreased from 50 ㎛ to under 10 ㎛. The composition distribution result revealed an even distribution when 2 wt% of polysiloxane was added but uneven distribution when over 3 wt% of polysiloxane was added due to decreased hardness by cluster. Therefore, the addition of an appropriate amount of 2 wt% polysiloxane reinforced the porous silver with open pores to offer application for jewelry usage.