• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.6-6
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• 2010

Indium Tin Oxide (ITO)를 포함한 Transparent Conduction Oxide (TCO)는 LCD, OLED와 같은 Display, 그리고 Solar Cell 등 광신호와 전기신호간 변환이 필요한 모든 Device에 반드시 필요한 핵심 물질로, 특히 고특성 Display의 투명전극에서 요청되는 95% 이상의 투과도와 $15\;{\Omega}/{\square}$ 이하의 면저항 특성을 동시에 만족할 수 있는 기술은 현재까지 Plasma Sputtering 공정으로 $160^{\circ}C$ 이상에서 증착된 ITO 박막이 유일하다. 그러나, 최근 차세대 기술로서 Plastic Film을 기반으로 하는 Flexible Display 및 Flexible Solar Cell 구현에 대한 요구가 급증하면서, Plastic Film 기판위에 Plasma Damage이 없이 상온에 가까운 저온 ($100^{\circ}C$ 이하)에서 특성이 우수한 ITO 투명전극을 형성 할 수 있는 기술의 확보가 중요한 현안이 되고 있다. 지난 10년 동안 $100^{\circ}C$이하 저온에서 고특성의 ITO 또는 TCO 박막을 얻기위한 다양한 연구와 구체적인 공정이 활발히 연구되어 왔으나, ITO의 결정화 온도 (통상 $150{\sim}180^{\circ}C$)이하에서 증착된 ITO박막은 비정질 상태의 물성적 특성을 보여 원하는 전기적, 광학적 특성확보가 어려웠다. 본 논문에선 기본적으로 절연체 특성을 가져야 하는 산화물인 TCO가 반도체 또는 도체의 물리적 특성을 보여주는 기본원리의 고찰을 토대로, 재료학적 특성상 Crystalline 구조를 보여야 하는 ITO (Complex Cubic Bixbyte Structure)가 Plasma Sputtering 공정으로 저온에서 증착될 때 비정질 구조를 갖게 되는 원인을 규명하고, 이를 바탕으로 저온에서 증착된 ITO가 Crystalline 구조를 유지 할 수 있게 하고, Stress Control에 유리한 Nano-Crystalline 박막을 형성하면서 Crystallinity를 임의로 조절 할 수 있는 새로운 기술인 Magnetic Field Shielding Sputtering (MFSS) 공정과 최근 성과를 소개한다. 한편, 또 다른 새로운 저온 TCO 박막형성 기술로서, 유기반도체와 같은 Process Damage에 매우 취약한 유기물 위에 Plasma Damage 없이 TCO 박막을 직접 형성할 수 있는 Neutral Beam Assisted Sputtering (NBAS) 기술의 원리를 설명하고, 본 공정을 적용한 Top Emission OLED 소자의 결과를 소개한다. 또한, 고온공정이 수반되는 Solar Cell용 투명전극의 경우, 통상의 TCO박막이 고온공정을 거치면서 전기적 특성이 열화되는 원인을 규명하고, 이에 대한 근본적 해결 방법으로 ITO 박막의 Dopant인 Tin (Sn) 원자의 활성화를 증가시킨 Inductively Coupled Plasma Assisted DC Magnetron Sputtering (ICPDMS)의 원리와 박막의 물성적 특성과 내열 특성을 소개한다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 II
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• pp.727-730
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• 2003

Thin tin oxide film with nano-size particle was prepared on silicon substrate by hydrothermal synthetic method and successive sol-gel spin coating method. The fabrication method of tin oxide film with ultrafine nano-size crystalline structure was tried to be applied to fabrication of micro gas sensor array on silicon substrate. The tin oxide film on silicon substrate was well patterned by chemical etching upto 5${\mu}{\textrm}{m}$width and showed very uniform flatness. The tin oxide film preparation method and patterning method were successfully applied to newly proposed 2-dimensional micro sensor fabrication.

• 한국산학기술학회논문지
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• 제19권1호
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• pp.699-704
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• 2018

일차원 나노구조물은 양자 갇힘 효과 및 나노와이어가 갖는 체적 대비 높은 표면적 비에 기인하는 독특한 전기적, 광학적, 광전기적, 전기화학적 특성으로 인하여 많은 주목을 받아왔다. 특히 수직으로 성장된 나노와이어는 체적 대비 높은 표면적 비의 특성을 나타낸다. VLS(Vapor-Liquid-Soild) 공정은 나노구조물의 성장 과정에서 자기정렬 효과 때문에 더욱 주목을 받는다. 본 연구에서는 두 영역 열화학 기상증착법을 이용하여 Si\$SiO_2$(300 nm)\Pt 기판 위에 수직으로 정렬된 실리콘 옥사이드 나노기둥을 VLS 공정으로 성장시켰다. 성장된 실리콘 옥사이드 나노기둥의 형상과 결정학적 특성을 주사전자현미경 및 투과전자현미경으로 분석하였다. 그 결과 성장된 실리콘 옥사이드 나노기둥의 지름과 길이는 촉매 박막의 두께에 따라 변하였다. 실리콘 옥사이드 나노 기둥의 몸체는 비정질 상을 나타내었으며, Si과 O로 구성되어 있었다. 또한 성장된 실리콘 옥사이드 나노 기둥의 머리는 결정성을 나타내었으며, Si, O, Pt 및 Ti으로 구성되어 있었다. 실리콘 옥사이드 나노 기둥의 수직 정렬은 촉매물질인 Pt/Ti 합금의 결정성 정렬 선호에 기인하는 것으로 판단되며, 수직 성장된 실리콘 옥사이드 나노기둥은 기능성 나노소재로 활용이 가능할 것으로 기대된다.

• Bulletin of the Korean Chemical Society
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• 제29권8호
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• pp.1485-1490
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• 2008

Dumbbell-shaped aromatic amphiphilic molecules consisting of a dodeca-p-phenylene as a rigid segment and oligoether dendrons as a flexible chains were synthesized, characterized, and their aggregation behavior was investigated in the bulk and at the air-water interface. In contrast to the molecule 2 which shows a nematic liquid crystalline state, molecule 1 based on shorter dendritic chains was observed to self-assemble into a 3-D primitive orthorhombic supercrystal. And molecule 1 at the air-water interface was observed to reorganize from circular plates to ring structures by lateral compressions.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 추계학술발표대회
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• pp.40.2-40.2
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• 2009

Using the favorable resorption behavior of amorphous Calcium phosphate (CaP) we fabricated a gelatin basednano fibrous mat by electrospinning for using as a fast healing patch for minorbone defects. Bone is predominantly formed by an inorganic phase of nano-crystalline HAp materials and nano fibrous protein material of collagen. The osteoblast cells, which are the bone formation cells and are key to the new bone formation, receive these materials to form new bone. Taking these considerations we make a new nano fibrous mat of amorphous CaP and gelatin, which is derived from collagen itself. A polymer carrier of poly caprolactone(PCL) was used in the system to stabilize the materials in biological condition. The electrospinning conditions were optimized for smooth mat without any droplet formation. The fabricated mat was characterized for its morphologyby SEM. Mechanical properties like tensile strength was evaluated. To investigate the bio-compatibility we performed the MTT assay and investigated its resorption behavior and apatite formation behavior by SBF immersion.

• Journal of Magnetics
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• 제16권4호
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• pp.403-407
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• 2011

Metal-insulator type, nano-granular soft magnetic films have been reviewed from the viewpoint of high frequency magnetic materials. The formation of nano-granular structure is related to the magnitude of heat of formation of intergranule materials. Variation of the ratio of granule phase to intergranule phase in the film is found to produce various characteristics in the magnetic properties of the film. The HRTEM observation reveals that neighboring granules in the film with above 60 at.% Co, contact at considerable points and the films show soft magnetic properties which are explainable in terms of the random anisotropy model for nano-crystalline materials. Addition of Ni group elements in Co-O based films enhances their anisotropy field up to 400 Oe and they exhibit excellent frequency response of permeability. Also, large electromagnetic noise suppression effect is demonstrated as one of their potential applications.

• Journal of Magnetics
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• 제13권3호
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• pp.106-109
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• 2008

Almost monodisperse iron oxide nanoparticles with an average particle size ranging from 5 to 43 nm were fabricated using an environmentally friendly starting material, ferrous acetate. The smallest particles were formed in the presence of a reductant, 1,2-dodecanediol, while the particle size increased with increasing concentration of dispersing agents. The dispersants consisted of various combinations of oleic acid, oleylamine, trioctylphosphine, and polyvinylpyrrolidone. The threshold temperature to form crystalline particles was found to be $240^{\circ}C$. The 43 nm nanoparticles exhibited a room temperature saturation magnetization and coercivity of 57 emu/g and 47 Oe, respectively.

• 한국세라믹학회지
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• 제37권7호
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• pp.625-631
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• 2000

In this study, the characteristics and sinterablities of TiO2 powders which were fabricated on sol-gel process and supercritical fluid process were examined. The powders fabricated on sol-gel process were amorphous. The particle size and shape were changed with the amount of water used for hydrolysis of titanium ethoxide. The powders were changed from amorphous to crystalline by heating at 400℃. The crystalline anatase TiO2 powders were directly prepared in ethanol supercritical fluid condition that temperature was 270±3℃ and pressure was 7.3 MPa. It's primary crystalline size was 20 nm and agglomerated as spherical shape whose size was 0.7∼1㎛. The powders prepared on sol-gel process were not sintered densely at 900℃ because of abnormal grain growth. However, the powders which prepared on supercritical fluid process were sintered densely at the comparatively low temperature of 800℃ by ideal growth of grain, which are fired at 900℃.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1328_1329
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• 2009

Nano porous indium tin oxide (ITO) powder was synthesized employing a new route sol-gel combustion hybrid method using Ketjen Black as a fuel. The nano porous ITO powder was composed of $SnCl_4$-98.0% and $In(NO_3)_3{\cdot}XH_2O$-99.999%, produce with a $NH_4OH$ with sol-gel method as a catalyst [1,2]. Crystal structures were examined by powder X-ray diffraction (XRD), and those results show shaper intensity peak at $25.6^{\circ}(2{\Theta})$ of $SnO_2$ by increased sintering temperature. A particle morphology as well as crystal size was investigated by scanning electron microscopy(FE-SEM), and the size of the nano porous powder was found to be in the range of 20~30nm. ITO films could controlled by nano porous powder at various sintering temperature in this paper[3,4]. The sol-gel combustion method was offered simple and effective route for the synthesis of nano porous ITO powder[5].

• Journal of Information Display
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• 제11권3호
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• pp.109-112
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• 2010

The solid phase compositions and dielectric properties of silicon nitride ($SiN_x$) films prepared using the plasma enhanced chemical vapor deposition (PECVD) technique at a low temperature ($200^{\circ}C$) were studied. Controlling the source gas mixing ratio, R = $[N_2]/[SiH_4]$, and the plasma power successfully produced both silicon-rich and nitrogen-rich compositions in the final films. The composition parameter, X, varied from 0.83 to 1.62. Depending on the film composition, the dielectric properties of the $SiN_x$ films also varied substantially. Silicon-rich silicon nitride (SRSN) films were obtained at a low plasma power and a low R. The photoluminescence (PL) spectra of these films revealed the existence of nano-sized silicon particles even in the absence of a post-annealing process. Nitrogen-rich silicon nitride (NRSN) films were obtained at a high plasma power and a high R. These films showed a fairly high dielectric constant ($\kappa$ = 7.1) and a suppressed hysteresis window in their capacitance-voltage (C-V) characteristics.