• EDISON SW 활용 경진대회 논문집
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• 제5회(2016년)
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• pp.299-304
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• 2016

2차원 반도체 소재의 경우 물질종류마다 내포하고 있는 고유결함에 의해서 Fermi-Level Pinning 이 발생하여 이로 인한 Schottky Barrier transistor로 동작을 하게 되며, 이는 접합부에 Carrier Injection 정도와 Schottky Barrier을 통과하는 Tunneling 정도에 의해서 소자의 특성이 결정 된다. 본 연구에서는 시뮬레이션을 통하여 2차원 반도체인 $MoS_2$소자를 설계하고, S/D Doping에 따라 접촉 저항 개선 효과와 소자의 동작특성이 어떠한 영향을 미치는지 연구하여 최대 $250cm^2/V{\cdot}sec$의 field effect mobility 의 결과를 얻었다. 또한 S/D doping 에 따라 각 저항 성분의 영향을 분석하였으며 면저항 및 접촉 저항 둘 다 doping 농도가 증가함에 따라 감소하는 결과를 나타내며, S/D doping의 영향은 접촉저항에서 더 크게 나타났다. 더불어 2차원 반도체의 Resistance network model 을 제안하여 subthreshold 영역에서는 $R_{ic}$, saturation 영역에서는 $R_{ish}$ 가 전체저항에서 주요한 변수로 전체저항식에 포함되어야 한다는 것을 시뮬레이션을 통해서 검증하였다.

• 공업화학
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• 제26권2호
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• pp.121-127
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• 2015

전기화학적 양극산화 기법으로 제조한 타이타늄 나노튜브는 타이타늄 특유의 강한 화학내구성 및 나노튜브의 높은 종횡비로 인하여 넓은 범위에 응용된 소재이다. 전해질의 구성 성분과 종류, pH, 전압, 온도 그리고 양극산화 시간이 타이타늄 나노튜브의 성상을 결정짓는 요소들이며 도핑을 통해 촉매능을 부여할 수 있다. 비금속 및 금속 원소 모두 도핑 가능하며 도핑 방법 역시 다양하다. 도핑 방법에는 합금 양극산화, 열처리법, 함침법, 전기도금법 등 다양한 방법들이 이용되며 점차 간단하고 빠른 도핑 방법을 찾는 방향으로 연구가 진행되고 있다. 본 총설에서는 타이타늄 나노튜브의 생성 원리와 상용된 제법들에 관하여 기술하고 도핑과 그 응용 및 최근의 도핑 연구 동향을 다루도록 하겠다.

• 대한전자공학회논문지SD
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• 제37권4호
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• pp.25-30
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• 2000

금속 유도 측면 결정화에 의한 다결정 실리콘 박막 트랜지스터의 제작에서 이온 질량 주입이 MILC 속도 및 거동에 미치는 영향을 분석하였다. 비정질 실리콘에 도펀트를 주입하거나 이온충돌을 가하면 MILC의 속도가 50% 이상 감소하고 MILC선단이 불균일 해졌다. IMD에 따른 비정질 실리콘 박막의 성질 변화를 분석하기 위하여 자외선 반사도 및 표면 거칠기를 관찰하였고, 이온 충돌에 의한 표면 거칠기의 증가가 MILC 속도 감소와 균일도에 영향을 주는 것으로 나타났다.

• Journal of Magnetics
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• 제20권2호
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• pp.97-102
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• 2015

The waste of sintered Nd-Fe-B magnets was recycled using the method of dopingPrNd nanoparticles. The effect of PrNd nanoparticle doping on the magnetic properties of the regenerated magnets has been studied. As the content of the PrNd nanoparticles increases, the coercivity increases monotonically, whereas both the remanence and the maximum energy products reach the maximum values for 4 wt% PrNd doping. Microstructural observation reveals that the appropriate addition of PrNd nanoparticles improves the magnetic properties and refines the grain. Domain investigation shows that the self-pinning effect of the rare earth (Re)-rich phase is enhanced by PrNd nano-particle doping. Compared to the magnet with 4 wt% PrNd alloy prepared using the dual-alloy method, the regenerated magnet doped with the same number of PrNd nanoparticles exhibits better magnetic properties and a more homogeneous microstructure. Therefore, it is concluded that PrNd nanoparticle doping is an efficient method for recycling the leftover scraps of Nd-Fe-B magnets.

• Bulletin of the Korean Chemical Society
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• 제32권3호
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• pp.921-926
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• 2011

This study investigates a root cause of the improved rate performance of $LiFePO_4$ after metal doping to Fesites. This is because the metal doped $LiFePO_4$/C maintains its initial capacity at higher C-rates than undoped one. Using $LiFePO_4$/C and doped $LiFe_{0.97}M_{0.03}PO_4$/C (M=$Al^{3+}$, $Cr^{3+}$, $Zr^{4+}$), which are synthesized by a mechanochemical process followed by one-step heat treatment, the Li content before and after chemical delithiation in the $LiFePO_4$/C and the binding energy are compared using atomic absorption spectroscopy (AAS) and X-ray photoelectron spectroscopy (XPS). The results from AAS and XPS indicate that the low Li content of the metal doped $LiFePO_4$/C after chemical delithiation is attributed to the low binding energy induced by weak Li-O interactions. The improved capacity retention of the doped $LiFePO_4$/C at high discharge rates is, therefore, achieved by relatively low binding energy between Li and O ions, which leads to fast Li diffusivity.

• 한국응용과학기술학회지
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• 제19권2호
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• pp.97-102
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• 2002

Recently, the phosphorescent organic light-emitting devices (OLEDs) have been extensively studied for their high internal quantum efficiency. In this study, we synthesised several phosphorescent metal complexes, and certified their composition using NMR. We also investigated the characteristics of the phosphorescent OLEDs with the green emitting phosphor, $Ir(ppy)_{3}$. The devices with a structure of indium-tin-oxide(ITO)/N,N'-diphenyl-N,N'-(3-methylphenyI}-1,1'-biphenyl-4,4'-diamine (TPD)/metal complex doped in host materials/2,9-dimethyl-4,7-diphenyl-l,10-phenanthroline(BCP)/tris (8-hydroxyquinolinato) Aluminum($Alq_{3}$)/Li:Al/Al was fabricated, and its electrical and optical characteristics were studied. By changing the doping concentration of tris(2-phenylpyridine)iridium ($Ir(ppy)_{3}$), we fabricated several devices and investigated their characteristics.

• Transactions on Electrical and Electronic Materials
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• 제12권3호
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• pp.93-97
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• 2011

In this paper, we discuss design considerations for an n-channel metal-oxide-semiconductor field-effect transistor (MOSFET) with a lateral asymmetric channel (LAC) doping profile. We employed a 0.35 ${\mu}M$ standard complementary MOSFET process for fabrication of the devices. The gates to the LAC doping overlap lengths were 0.5, 1.0, and 1.5 ${\mu}M$. The drain current ($I_{ON}$), transconductance ($g_m$), substrate current ($I_{SUB}$), drain to source leakage current ($I_{OFF}$), and channel-hot-electron (CHE) reliability characteristics were taken into account for optimum device design. The LAC devices with shorter overlap lengths demonstrated improved $I_{ON}$ and $g_m$ characteristics. On the other hand, the LAC devices with longer overlap lengths demonstrated improved CHE degradation and $I_{OFF}$ characteristics.

• 한국재료학회지
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• 제14권4호
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• pp.293-299
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• 2004

Transition metal ions doped $TiO_2$ nanostructured powders were prepared with simply heating aqueous $TiOCl_2$ solutions, contained various metal ions (Ni, Al, Fe, Zr, and Nb) of 1.47 mol% added as metal-chlorides, at $100^{\circ}C$ for 4 hrs by homogeneous precipitation process under suppressing conditions of water vaporization. The characterizations for prepared $TiO_2$ powders were carried out to observe doping of metal ions, their concentrations and microstructures using XRD, UV-VIS (DRS), XPS, SEM, TEM and ICP. Also, photo-oxidative abilities were evaluated by decomposition of 4-chlorophenol (4CP) under ultraviolet light irradiations. No secondary oxide phases were formed in all the $VTiO_2$ powders, showing doping with various transition metal ions. When adding ions ($Ni^{2+}$ or$ Al^{3+ }$ and $Zr^{4+}$ ) having valance states or ionic radii greatly different from those of $Ti^{4+}$ , the $TiO_2$ powders of mixed anatase and rutile phases were formed, whereas in the case of additions of $^Fe{3+ }$ and $Nb^{ 5+}$ as well as no addition of metal ion the powders with pure rutile phase alone were formed. Among the prepared $TiO_2$ powders, Ni$^{2+}$ doped $TiO_2$ powders, containing a small amount of anatase phase, showed excellent photo-oxidative ability in 4CP decomposition because of relative decreases in electron-hole recombination and poisoning of $TiO_2$ surface during the photoreaction.n.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2002년도 High Temperature Superconductivity Vol.XII
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• pp.4-4
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• 2002

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2182-2187
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• 2007

The relative contributions of phonon and electron to the thermal conductivity of silicon film with varying doping density are evaluated from the modified electron-phonon interaction model, which is applicable to the micro/nanoscale simulation of energy transport between energy carriers. The thermal conductivities of intrinsic silicon layer thicknesses from 20 nm to 500 nm are calculated and extended to the variation in n-type doping densities from 1.0 ${\times}$ $10^{18}$ to 5.0 ${\times}$ $10^{20}$ $cm^{-3}$, which agree well with the experimental data and theoretical model. From simulation results, the phonon and electron contributions to thermal conductivity are extracted. The electron contribution in the silicon is found to be not negligible above $10^{19}$ $cm^{-3}$, which can be classified as semimetal or metal by the value of its electrical resistivity at room temperature. The thermal conductivity due to electron is about 57.2% of the total thermal conductivity at doping concentration 5.0 ${\times}$ $10^{20}$ $cm^{-3}$ and silicon film thickness 100 nm.