• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.32-32
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• 2009

실리콘 박막 태양전지에서 전면 투명전도막(TCO)은 태양전지의 전기, 광학적 특성을 결정하는 중요한 기능을 한다. ZnO:Al TCO는 기존에 사용되던 $SnO_2:F$와는 비정질 실리콘(a-Si:H) 박막 태양전지의 윈도우 층으로 사용되는 p a-SiC:H와의 일함수(work function) 차이로 인해 접촉전위(contact barrier)를 형성하게 되며 이로 인해 태양전지의 충진율(fill factor)이 $SnO_2:F$에 비해 감소하는 단점을 보인다. 본 연구에서는 ZnO:Al/p a-SiC:H 계면의 접촉전위 발생원인 및 태양전지 충진율 감소현상에 관한 정확한 원인규명을 위해 다양한 특성을 갖는 버퍼층을 삽입하여 계면특성 및 태양전지의 동작특성을 분석하고자 한다.

• Wind and Structures
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• 제20권2호
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• pp.237-247
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• 2015

Wind tunnel experiments are used to investigate the aerodynamic interactions between vehicles and wind barriers on a railway bridge. Wind barriers with four different heights (1.72 m, 2.05 m, 2.5 m and 2.95 m, full-scale) and three different porosities (0%, 30% and 40%) are studied to yield the aerodynamic coefficients of the vehicle and the wind barriers. The effects of the wind barriers on the aerodynamic coefficients of the vehicle are analyzed as well as the effects of the vehicle on the aerodynamic coefficients of the wind barriers. Finally, the relationship between the drag forces on the wind barriers and the aerodynamic coefficients of the vehicle are discussed. The results show that the wind barriers can significantly reduce the drag coefficients of the vehicle, but that porous wind barriers increase the lift forces on the vehicle. The windward vehicle will significantly reduce the drag coefficients of the porous wind barriers, but the windward and leeward vehicle will increase the drag coefficients of the solid wind barrier. The overturning moment coefficient is a linear function of the drag forces on the wind barriers if the full-scale height of the wind barriers $h{\leq}2.5m$ and the overturning moment coefficients $C_O{\geq}0$.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 학술대회 논문집 전문대학교육위원
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• pp.29-32
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• 2000

Ozone has been widely applied to many industrial fields because of its strong oxidation effects. Therefore, the studies have been progressed for the effective and high concentration of one generation. The silent or surface discharge have been mainly used for high concentration ozone generation until now. But these two types of ozone generators have shortcomings to be improved. In this study, the ozone generator which improved the shortcomings of above two type of ozone generators was proposed and manufactured for high concentration ozone generation. And the proposed ozone generator could generate the surface and barrier discharge simultaneously. For this purpose, a mesh type discharge electrodes were proposed and the experiments were fulfilled as a function of the widths and spacings of mesh electrodes and gap spacings between the dielectric barrier and mesh electrode. When the width of mesh electrode[WM] and spacing of mesh electrode[SM] are 0.3[mm] and 0.8[mm] respectively, the maximum ozone concentration of 2.96[vol%] was obtained at 5.6[kV], 830[mA], gap spacing (S)=0.65[mm].

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.72-72
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• 2010

Recent development of organic solar cell approaches the level of 8% power conversion efficiency by the introduction of new materials, improved material engineering, and more sophisticated device structures. As for interface engineering, various interlayer materials such as LiF, CaO, NaF, and KF have been utilized between Al electrode and active layer. Those materials lower the work function of cathode and interface barrier, protect the active layer, enhance charge collection efficiency, and induce active layer doping. However, the addition of another step of thin layer deposition could be a little complicated. Thus, on a typical solar cell structure of Al/P3HT:PCBM/PEDOT:PSS/ITO glass, we used Li:Al alloy electrode instead of Al to render a simple process. J-V measurement under dark and light illumination on the polymer solar cell using Li:Al cathode shows the improvement in electric properties such as decrease in leakage current and series resistance, and increase in circuit current density. This effective charge collection and electron transport correspond to lowered energy barrier for electron transport at the interface, which is measured by ultraviolet photoelectron spectroscopy. Indeed, through the measurement of secondary ion mass spectroscopy, the Li atoms turn out to be located mainly at the interface between polymer and Al metal. In addition, the chemical reaction between polymer and metal electrodes are measured by X-ray photoelectron spectroscopy.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.128.2-128.2
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• 2014

Long-wave infrared detectors using the type-II InAs/GaSb strained superlattice (T2SL) material system with the nBn structure were designed and fabricated. The band gap energy of the T2SL material was calculated as a function of the thickness of the InAs and GaSb layers by the Kronig-Penney model. Growth of the barrier material (Al0.2Ga0.8Sb) incorporated Te doping to reduce the dark current. The full width at half maximum (FWHM) of the 1st satellite superlattice peak from the X-ray diffraction was around 45 arc sec. The cutoff wavelength of the fabricated device was ${\sim}10.2{\mu}m$ (0.12eV) at 80 K while under an applied bias of -1.4V. The measured activation energy of the device was ~0.128 eV. The dark current density was shown to be $1.2{\times}10^{-5}A/cm^2$ at 80 K and with a bias -1.4 V. The responsivity was 1.9 A/W at $7.5{\mu}m$ at 80K and with a bias of -1.9V.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.433-433
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• 2011

Since the concept of graphene was established, it has been intensively investigated by researchers. The unique characteristics of graphene have been reported, the graphene attracted a lot of attention for material overcomes the limitations of existing semiconductor materials. Because of these trends, economical fabrication technique is becoming more and more important topic. Especially, the epitaxial growth method by sublimating the silicon atoms on Silicon carbide (SiC) substrate have been reported on the mass production of high quality graphene sheets. Although SiC exists in a variety of polytypes, the 3C-SiC polytypes is the only polytype that grows directly on Si substrate. To practical use of graphene for electronic devices, the technique, forming the graphene on 3C-SiC(111)/Si structure, is much helpful technique. In this paper, we report on the growth of graphene on 3C-SiC(111) surface. To investigate the morphology of formed graphene on the 3C-SiC(111) surface, the radial distribution function (RDF) was calculated using molecular dynamics (MD) simulation. Through the comparison between the kinetic energies and the diffusion energy barrier of surface carbon atoms, we successfully determined that the graphitization strongly depends on temperature. This graphitization occurs above the annealing temperature of 1500K, and is also closely related to the behavior of carbon atoms on SiC surface. By analyzing the results, we found that the diffusion energy barrier is the key parameter of graphene growth on SiC surface.

• 센서학회지
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• 제8권6호
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• pp.448-453
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• 1999

Pd-SiC 쇼트키 다이오드를 이용한 수소 가스 센서를 개발하였다. Pd-SiC 쇼트키 다이오드의 수소 가스 감지특성을 I-V 및 ${\Delta}I$-t 분석을 통하여 수소 농도와 온도 함수로서 분석하였다. 또한, 수소 흡착에 의한 Pd-SiC 쇼트키 다이오드의 장벽 높이의 변화를 조사하였다. 수소 원자의 흡착이 다이오드의 장벽 높이의 변화와 관계되는 것을 I-V 분석을 이용하여 정상 상태에서의 가스 반응 속도론에 의하여 확인하였다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권7호
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• pp.388-393
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• 2000

Hydrogen-sensing behaviors of Pd- and Pt-SiC Schottky diodes, fabricated on the same SiC substrate, have been systematically compared and analyzed as a function of hydrogen concentration and temperature by I-V and$\DeltaI-t$ methods under steady-state and transient conditions. The effects of hydrogen adsorption on the device parameters such as the barrier height are investigated. The significant differences in their hydrogen sensing characteristics have been examined in terms of sensitivity limit, linearity of response, response rate, and response time. For the investigated temperature range, Pd-SiC Schottky diode shows better performance for H2 detection than Pt-SiC Schottky diode under the same testing conditions. The physical and chemical mechanisms responsible for hydrogen detection are discussed. Analysis of the steady-state reaction kinetics using I-V method confirmed that the atomistic hydrogen process is responsible for the barrier height change in the diodes.

• 전자공학회논문지A
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• 제32A권7호
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• pp.51-57
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• 1995

The theoretical analysis for AlInAs/GaInAs resonant tunneling diodes (RTDs), which have shown the improved negative differential resistance (NDR) characteristics, has scarcely been made in comparison with AlGaAS/GaAs RTDs. In this paper, the static current-voltage relation of Al$_{0.48}In_{0.52}As/Ga_{0.47}In_{0.53}$As RTDs were numerically estimated by using a self-consistent method. Assuming a simplified RTD with single quantum well structure and spacer layers, the peak current density (J$_{P}$) and the peak-to-valley current ratio (PVCR) were analysed as the function of the thickness of the well, the barrier and the spacer layer, and temperature. As the results, the peak current density and the peak-to-valley current ratio indicated a reciprocal relation roughly in respect to the thicknesses of the well and the barrier, and it was theoretically predicted that it be not attainable to provide a high peak current desity (J$_{P}$) over 1${\times}10^{5}A/cm^{2}$ as well as the large peak-to-valley current ratio (PVCR) over 10 that were the the critical conditions for the practical use.

• 한국세라믹학회지
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• 제54권5호
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• pp.443-447
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• 2017

The initial reaction of hexachlorodisilane ($Si_2Cl_6$, HCDS) on amorphous silica ($SiO_2$) surface for atomic layer deposition was investigated using density functional theory. Two representative reaction sites on the amorphous $SiO_2$ surface for HCDS reaction, a surface hydroxyl and a two-membered ring, were considered. The reaction energy barrier for HCDS on both sites was higher than its adsorption energy, indicating that it would desorb from the surface rather than react with the surface. At high temperature range, some HCDSs can have kinetic energy high enough to overcome the reaction energy barrier. The HCDS reaction on top of the reacted HCDS was investigated to confirm its self-limiting characteristics.