• Transactions on Electrical and Electronic Materials
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• 제15권4호
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• pp.193-197
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• 2014

Si-carbon composites as anode materials for lithium rechargeable batteries were prepared simply by mixing Si nanoparticles with carbon black and/or graphite through a solution process. Si nanoparticles were well dispersed and deposited on the surface of the carbon in a tetrahydrofuran solution. Si-carbon composites showed more than 700 mAh/g of initial capacity under less than 20% loading of Si nanoparticle in the composites. While the electrode with only Si nanoparticles showed fast capacity fading during continuous cycling, Si-carbon composite electrodes showed higher capacities. The cycle performances of Si nanoparticles in composites containing graphite were improved due to the role of the graphite as a matrix.

• Journal of Electrochemical Science and Technology
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• 제4권3호
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• pp.108-112
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• 2013

Lithium diffusivity of the silicon (Si)-based materials of Si-Cu and $SiO_x$ (x = 0.4, 0.85) with improved interfacial stability to electrolyte have been determined, using variable rate cyclic voltammetry with film model electrodes. Lithium diffusivity is found to depend on the intrinsic properties of anode material and electrolyte; the fraction of oxygen for $SiO_x$ (x = 0.4, 0.85), which is directly related to electrical conductivity, and the electrolyte type with different ionic conductivity and viscosity, carbonate-based liquid electrolyte or ionic liquid-based electrolyte, affect the lithium diffusivity.

• Journal of Korean Vacuum Science & Technology
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• 제3권1호
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• pp.54-58
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• 1999

We deposited diamond-like carbon (DLC) films using ion beam sputtering of a graphite target on flat substrates for use as a thin film field emitter. An n-type silicon wafer, titanium-coated silicon, and indium tin oxide (ITO) coated glass were used as a substrate. All films exhibited a sudden increase in the emission after a breakdown occurred at high voltage. The morphology of the films after the breakdown depended on the substrate. On ITO and Ti substrates, the DLC film peeled off upon breakdown, but on the Si substrate the surface melting due to breakdown resulted in the formation of various structures such as a sharp point, mound, and crater. By scanning the deformed surface with a tip anode, we found that the emission was concentrated at the deformed sites, indicating that the field enhancement due to the morphology change was responsible for the increased emission.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.241-241
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• 2008

Macrofore formation in silicon and other semiconductors using electrochemical etching processes has been, in the last years, a subject of great attention of both theory and practice. Its first reason of concern is new areas of macropore silicone applications arising from microelectromechanical systems processing (MEMS), membrane techniques, solar cells, sensors, photonic crystals, and new technologies like a silicon-on-nothing (SON) technology. Its formation mechanism with a rich variety of controllable microstructures and their many potential applications have been studied extensively recently. Porous silicon is formed by anodic etching of crystalline silicon in hydrofluoric acid. During the etching process holes are required to enable the dissolution of the silicon anode. For p-type silicon, holes are the majority charge carriers, therefore porous silicon can be formed under the action of a positive bias on the silicon anode. For n-type silicon, holes to dissolve silicon is supplied by illuminating n-type silicon with above-band-gap light which allows sufficient generation of holes. To make a desired three-dimensional nano- or micro-structures, pre-structuring the masked surface in KOH solution to form a periodic array of etch pits before electrochemical etching. Due to enhanced electric field, the holes are efficiently collected at the pore tips for etching. The depletion of holes in the space charge region prevents silicon dissolution at the sidewalls, enabling anisotropic etching for the trenches. This is correct theoretical explanation for n-type Si etching. However, there are a few experimental repors in p-type silicon, while a number of theoretical models have been worked out to explain experimental dependence observed. To perform ordered macrofore formaion for p-type silicon, various kinds of mask patterns to make initial KOH etch pits were used. In order to understand the roles played by the kinds of etching solution in the formation of pillar arrays, we have undertaken a systematic study of the solvent effects in mixtures of HF, N-dimethylformamide (DMF), iso-propanol, and mixtures of HF with water on the macrofore structure formation on monocrystalline p-type silicon with a resistivity varying between 10 ~ 0.01 $\Omega$ cm. The etching solution including the iso-propanol produced a best three dimensional pillar structures. The experimental results are discussed on the base of Lehmann's comprehensive model based on SCR width.

• 한국분말재료학회지
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• 제24권1호
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• pp.24-28
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• 2017

Silicon alloys are considered promising anode active materials to replace Li-ion batteries by graphite powder, because they have a relatively high capacity of up to 4200 mAh/g, and are environmentally friendly and inexpensive ECO-materials. However, its poor charge/discharge properties, induced by cracking during cycles, constitute their most serious problem as anode electrode. In order to solve these problems, Si-Ge-Al alloys with porous structure are designed as anode alloy powders, to improve cycling stability. The alloys are melt-spun to obtain the rapidly solidified ribbons, and then ball-milled to make fine powders. The powders are etched using 1 M HCl solution, which gives the powders a porous structure by removing the element Al. Subsequently, in this study, the microstructures and the characteristics of the etched powders are evaluated for application as anode materials. As a result, the etched porous powder shows better electrochemical properties than as-milled Si-Ge-Al powder.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제36회 동계학술대회 초록집
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• pp.192.1-192.1
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• 2009

• 한국재료학회:학술대회논문집
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• 한국재료학회 2005년도 춘계학술발표대회 및 제8회 신소재 심포지엄 논문개요집
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• pp.207-207
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• 2005

• Korean Chemical Engineering Research
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• 제59권1호
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• pp.35-41
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• 2021

차세대 리튬이차전지용 음극활물질로 각광을 받고 있는 실리콘은 높은 이론용량을 가지고 있어 상용화를 하기 위해 많은 연구가 진행되었다. 하지만 실리콘은 충방전시 부피팽창이 심하고, 전기전도도가 낮은 단점을 가지고 있다. 이러한 문제를 해결하기 위해서 실리콘 표면에 SiO2를 형성시키고, 탄소를 코팅함으로써 실리콘의 부반응을 억제시키고 전기전도도를 향상시켰다. 추가적으로 CNF와 CNT를 복합적으로 첨가하여 부피팽창에 대한 완충효과를 부여하고 전기전도도를 향상시켰다. 제조된 샘플은 XRD, SEM, EDS로 물리적 특성 분석을 실시하였으며, 전기화학적 특성은 전기전도도, EIS, CV 그리고 사이클 테스트를 통해 분석하였다. (Si/SiO2/C)+CNT&CNF 복합체의 경우 다른 샘플들에 비하여 높은 전기전도도 및 낮은 전하전달저항을 보여주었으며, 사이클테스트 결과 첫 번째 사이클에서 1528 mAh/g 그리고 50번째 사이클에서 1055 mAh/g의 용량을 가졌으며 83%의 용량 유지율을 보여주었다.

• 한국정보통신학회논문지
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• 제18권6호
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• pp.1407-1412
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• 2014

근적외선 파장대역 850 nm ~ 1000 nm에서 레이저를 검출하기 위해 포토다이오드의 분광감응도를 향상시키고자 본 논문에서 실리콘 기반 고감도 PIN 포토 다이오드를 제작하고 전기적 및 광학적 특성을 분석하였다. 제작된 소자는 TO-18형으로 패키징 하였고 포토다이오드의 전기적 특성으로 역 바이어스 전압이 5V일 때 암전류는 Anode 1과 Anode 2는 약 0.055 nA 의 값을 나타내었으며 정전용약은 0V 일 때 1 kHz 주파수 대역에서 약 19.5 pF, 200 kHz 주파수 대역에서 약 19.8 pF의 적은 정전용약을 나타내었다. 또한 출력신호의 상승시간은 10 V의 전압일 때 약 30 ns의 고속 응답특성을 확인하였다. 광학적 특성 분석으로는 880 nm에서 최대 0.66 A/W의 분광감응도 값을 나타내었고 1000 nm에서는 0.45 A/W로 비교적 우수한 분광감응도를 나타내었다.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2004년도 추계학술대회
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• pp.99-102
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• 2004

Display process has adopted RCA clean, being applied to large area and coped with environmental issue for last ten years. However, the approaching concept of ozonized, hydrogenised, or electrolyzed water cleaning technologies is within RCA clean paradigm. In this work, only electrolyzed anode water was applied to clean particles and organics as well as metals based on Pourbaix concept, and as a test vehicle, MgO particles were introduced to prove the new concept. The electrolyzed anode water is very oxidative with high oxidation reduction potential(ORP) and low in pH of more than 900mV and 3.1, respectively. MgO particles were immerged in the anode water and its weight losses due to dissolution were measured with time. Weight losses were in the ranges of 100 to 500 micrograms in 250m1 anode waters depending on their ORP and pH. Therefore it was concluded that the cleaning radicals in the anode water was at least in the range of 1 to 5E20 ea per 250 ml anode water equivalent to IE18 ea/cm3. Hence it can be assumed that the anode water be applied to display cleaning since 1E10 to IE15 ea/cm3 ranges of contaminants are being treated. In addition, it was observed that anode water does not develop micro-roughness on hydrophobic surface while it does on the native silicon oxide.