• Title/Summary/Keyword: accumulation charge

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SPACE CHARGE IN PE LAMINATE (PE Laminate의 공간전하 형성)

  • Roh, Hong-S.;Lee, Jae-Y.;Han, Jae-H.;Suh, Kwang-S.
    • Proceedings of the KIEE Conference
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    • 1994.07b
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    • pp.1428-1430
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    • 1994
  • The accumulation of space charge in PE/PE/PE laminates was investigated using the low density polyethylenes having different melt indices from 0.25 to 45 g/10 min. Both heterocharge and homocharge accumulated in parent polyethylenes depend on the value of melt index. A general rule found in this study was that the heterocharge decreases as the melt index increases and finally the homocharge accumulates when the melt index is very high. Because of this reason, PE laminates showed different charge formation characteristics depending on melt index of polyethylene. Details of up to date results are described in the text.

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A Study on Threshold Voltage and I-V Characteristics by considering the Short-Channel Effect of SOI MOSFET (SOI MOSFET의 단채널 효과를 고려한 문턱전압과 I-V특성 연구)

  • 김현철;나준호;김철성
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.31A no.8
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    • pp.34-45
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    • 1994
  • We studied threshold voltages and I-V characteristics. considering short channel effect of the fully depleted thin film n-channel SOI MOSFET. We presented a charge sharing model when the back surface of short channel shows accumulation depletion and inversion state respectively. A degree of charge sharing can be compared according to each of back-surface conditions. Mobility is not assumed as constant and besides bulk mobility both the mobility defined by acoustic phonon scattering and the mobility by surface roughness scattering are taken into consideration. I-V characteristics is then implemented by the mobility including vertical and parallel electric field. kThe validity of the model is proved with the 2-dimensional device simulation (MEDICI) and experimental results. The threshold voltage and charge sharing region controlled by source or drain reduced with increasing back gate voltage. The mobility is dependent upon scattering effect and electric field. so it has a strong influence on I-V characteristics.

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A study on the characteristics of inner cell pressure for sealed type Ni-MH rechargeable battery using Zr-based hydrogen storage alloy as anode (Zr-based 수소저장합금을 음극으로 사용한 밀패형 Ni-MH 2차전지의 내압특성에 관한 연구)

  • Kim, Dong-Myung;Lee, Ho;Jang, Kuk-Jin;Lee, Jai-Young
    • Journal of Hydrogen and New Energy
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    • v.8 no.2
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    • pp.79-90
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    • 1997
  • Extensive work has been done on investigating the inner cell pressure characteristics of sealed type Ni-MH battery in which Zr-Ti-Mn-V-Ni alloy is used as anode. The inner cell pressure of this type Ni-MH battery much more increases with the charge/discharge cycling than that of the other type Ni-MH battery where commercialized $AB_5$ type alloy is used as anode. The increase of inner cell pressure in the sealed type Ni/MH battery using Zr-Ti-Mn-V-Ni alloy system is mainly due to the accumulation of oxygen gas during charge/discharge cycling. The accumulation of oxygen gas arises mainly due to the low rate of oxygen recombination on the MH electrode surface during charge/discharge cycling. The difference of oxygen recombination rate between $AB_5$ type electrode and Zr-Ti-Mn-V-Ni electrode is caused by the difference of electrode reaction surface area resulting from different particle size after their activation and the difference of surface catalytic activity for oxygen recombination reaction, respectively. After EIS analysis, it is identified that the surface catalytic activity affects much more dominantly on the oxygen recombination reaction than the reaction surface area does. In order to suppress the inner cell pressure of Ni-MH battery where Zr-Ti-Mn-V-Ni is used as anode, it is suggested that the surface catalytic activity for oxygen recombination should be improved.

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Experiments & numerical analysis of charge accumulation and flat band voltage shifts in irradiated MIS capacitor (放射線이 照射된 MIS capacitor의 電荷 蓄積 및 flat band 전압 이동에 대한 實驗 및 數値的 硏究)

  • 황금주;김홍배;손상희
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.44 no.4
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    • pp.483-489
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    • 1995
  • To investigate the mechanism generated by irradiation in the insulator layer irradiated MIS (Metal - Insulator - Semiconductor) device, the various types of MIS capacitors depending on insulator thickness, insulator types and implanted impurities are fabricated on the P-type wafer. MIS capacitors exposed by 1Mrad Co$^{60}$ .gamma.-ray are measured for flat band voltage and charge density shifts pre- and post-irradiation. The measuring results of post-irradiation show the flat band voltage shifting toward negative direction and charge density increasing regardless of parameters. This results have a good agreement with calculated data by computer simulation. Si$_{3}$N$_{4}$ layers have a good radiation-hardness than SiO$_{2}$ layers compared to the results of post-irradiation. Also, radiation-induced negative trap is discovered in the implanted insulator layer. Using numerical analysis, four continuty equations (conduction-band electrons continuity equation, valence-band holes continuity equation, trapped electrons continuity equation, trapped holes continuity equation) are solved and charge distributions according to the distance and Si-Insulator interface states are investigated.

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Effect of Surface Charge in Hydrophobicity of Insulating Material and Decay of Surface Voltage after Corona Charging

  • Huh, Chang-Su;Youn, Bok-Hee;Seo, You-Jin;Hwang, Sun-Mook
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.05e
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    • pp.1-5
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    • 2003
  • This paper presented the effects of accumulation of surface charges on hydrophobicity level and the surface states of silicone polymer used for outdoor insulator treated by ultraviolet irradiation and corona discharge through measuring surface voltage decay of a corona-charged specimen were investigated. The surface resistivity by the method of the surface potential decay was compared with the value by the three electrodes methods. From this study, it was found that the accumulation of surface charges above a critical surface voltage on silicone insulating materials could lead to the temporary loss of surface hydrophobicity. In addtion, uv stress lead to a longer decay time of surface charges. We could conclude that the effects of surface charges on hydrophocity level and the changes of surface state by various artificial treatments were understood through a trend of surface potential decay.

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Effects of Surface Charges on Hydrophobicity and Surface Potential Decay with Various Surface States of Silicone Rubber for Outdoor Insulator (옥외용 실리콘 절연재료의 발수성에 미치는 표면전하의 영향과 표면 상태에 따른 표면전위 감쇠)

  • 연복희;박충렬;허창수
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.15 no.8
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    • pp.678-686
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    • 2002
  • This paper presents the effects of accumulation of surface charges on hydrophobic level and the changes of surface potential decay with various artificial environment treatments on high temperature vulcanized (HTV) silicone rubber used for outdoor insulating material. For this study, the charging apparatus by corona discharge, in which grid electrode was installed between the main corona and ground electrode, was used. From this study, it was found that the accumulation of surface charges above a critical surface potential on silicone insulating materials could lead to the temporary loss of surface hydrophobicity. In addition, corona stress and water absorption stress increase the decay rate of surface charges of HTV silicone rubber, while ultraviolet (UV) stress causes longer decay time. We could conclude that the effects of surface charges on hydrophobicity level and the changes of surface state by various artificial treatments were found through a trend of surface potential decay.

High Efficiency Control scheme of EDLC for DVR System (DVR 시스템을 위한 EDLC의 고효율 제어 기법)

  • Han Jong-Hee;Jeon Hee-Jong;Lim Byung-Kuk;Shon Jin-Geun;Park Jong-Chan
    • Proceedings of the KIPE Conference
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    • 2006.06a
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    • pp.421-423
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    • 2006
  • In this paper, we propose EDLC's high effective operating techniques. EDLC is energy storage device that has advantages of electrolytic capacitor and accumulation capacitor and that supplements defect such as energy storing accumulation capacity, life time and safety. But, EDLC needs for more complex control scheme because is influenced directly in efficiency and life time by charge and discharge control method. In this paper, DVR system's performance is proposed by EDLC's high effective operating technique.

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Electron Accumulation in LaAlO3/SrTiO3 Interfaces by the Broken Symmetry of Crystal Field

  • Choe, Hui-Chae;Park, Ha-Yan;Jeong, Yong-Jae
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.02a
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    • pp.452-452
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    • 2011
  • Using ab initio calculations, we reveal the origins of the extraordinarily increased electric conductivity of the LaAlO3/SrTiO3 interface. In both of the two (LaAlO3)m/ SrTiO3 heterojunction models (m=3, 5), the oxygen atoms in the cells were displaced toward the n-type interface and the Ti-centered octahedron structure was compressed along the [001] direction by the atomic reconstructions at the (LaAlO3)m/(SrTiO3)4 interfaces. As a result, the 3dxy orbital of the Ti atom was preferentially occupied due to the lowered energy state of the 3dxy orbital, which arises from the crystal field asymmetry. We reason that the extra electrons occupy the 3dxy orbital are accumulated at the interface by the displacement of the oxygen atoms. This accumulation contributes to the conductivity of the n-type interface. In addition, through a comparison of the atomic displacements and charge accumulation amounts between the two thickness models (m=3, 5), the thickness-dependency of the conductivity can be explained.

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Improvement of Hybrid EL Efficiency in Nanoparticle EL Devices by Insertion of the Layers of PVK and BaF2

  • Lee, Jun-Woo;Cho, Kyoung-Ah;Kim, Hyun-Suk;Park, Byoung-Jun;Kim, Sang-Sig;Kim, Sung-Hyun
    • Transactions on Electrical and Electronic Materials
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    • v.6 no.3
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    • pp.101-105
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    • 2005
  • Electroluminescence(EL) and current-voltage(I-V) characteristics of hybrid EL devices containing Pr and Mn co-doped ZnS nanoparticles were investigated in this study. For the insertion of a hole transport layer of poly (N-vinyl carbazole)(PVK), the current level became lower due to the accumulation of electrons at the interface between PVK and nanoparticles. When both PVK and buffer layer $BaF_2$ were simultaneously introduced, the enhanced EL efficiency and improved I-V characteristics were obtained. This results from the additional increase of hole injection owing to the internal field induced by the significant accumulation of electrons at the interface. The presence of buffer layer $BaF_2$ together with PVK makes it possible the charge accumulation enough to induce the sufficient internal field for further hole injection.

A Study on Space Charge of Organic Pentacene/metal Interface (유기물 Pentacene 박막과 금속 계면에서의 Space Charge 연구)

  • Yoon, Young-Woon;Babajayan, Arsen;Lee, Hoo-Neung;Kim, Song-Hui;Lee, Kie-Jin
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.20 no.1
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    • pp.41-46
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    • 2007
  • Surface potential properties at the interface of pentacene thin films on gold (Au) and aluminum (Al) surfaces were investigated by using a near-field scanning microwave microprobe (NSMM). The surface potential formed across the pentacene film was observed by measuring the microwave reflection coefficient $S_{11}$ and compared with the result of a Kelvin-probe method. The obtained reflection coefficient ${\Delta}S_{11}$ of the pentacene thin films on Al was decreased as the pentacene film thickness increased due to the increased accumulation of negative space charges, while for Au ${\Delta}S_{11}$ was essentially constant.