• 제목/요약/키워드: Space charge field

검색결과 172건 처리시간 0.023초

폴리이미드 박막의 공간전하현상 (Space Charge Phenomena in Polyimide Films)

  • 윤주호;최용성;이경섭
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2007년도 추계학술대회 논문집
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    • pp.311-312
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    • 2007
  • Polyimide is widely used as a high-temperature insulating material. Space charge distributions in polyimide (PI) films strongly depend upon electric field, temperature, water content and so on. We observed space charge distributions in PI films with various water contents. When a dc field was applied to as-received PI films or water-treated PI films, positive and negative homo space charges were observed near the respective electrodes at 333 K. In dried PI films, the homo space charges were much reduced, and positive and negative hetero space charges in the bulk were clearly observed. The space charge amounts in water-treated PI films were smaller than in as-received ones, while the current density in water-treated PI film was larger than that in as-received one by two or more orders of magnitude. These suggest not only that the charge injection from the electrode is enhanced by absorbed water but also that absorbed water makes carriers mobile. The decay of space charge was also faster in water-treated PI than in as-received or dried one. This also supports the enhancement of apparent mobilities of carriers in PI by absorbed water.

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Photorefractive Performance of Poly[methyl-3-(9-carbazolyl) propylsiloxane] Based Composites Sensitized with Poly(3-hexylthiophene) in a 0.2-1wt % Range

  • Oh, Jin-Woo;Kim, Nak-Joong
    • Bulletin of the Korean Chemical Society
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    • 제31권1호
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    • pp.41-46
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    • 2010
  • In this work, we report on the characterization of six low-$T_g$ poly[methyl-3-(9-carbazolyl) propylsiloxane] based photorefractive (PR) composites sensitized with poly(3-hexylthiophene) (P3HT) in different concentrations, ranging from 0.2 to 1 wt %. At 632.8 nm, photoconductivity, space charge field, refractive index modulation, and grating buildup time were measured versus external electric field. The photoconductivity was strongly dependent on the visible light absorption and mobility. The magnitude of space charge field was affected by the conductivity contrast $\sigma_{ph}/(\sigma_{ph}+\sigma_d)$. The refractive index modulation increased with the magnitude of space charge field and the PR grating buildup speed increased with the photoconductivity.

폴리이미드 박막의 공간전하현상 및 수분의 영향 (Space Charge Phenomena in Polyimide Films and Effects of Absorbed Water)

  • 윤주호;최용성;황종선;이경섭
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2008년도 춘계학술대회 논문집 센서 박막재료연구회 및 광주 전남지부
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    • pp.82-85
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    • 2008
  • Polyimide is widely used as a high-temperature insulating material. Space charge distributions in polyimide (PI) films strongly depend upon electric field, temperature, water content and so on. We observed space charge distributions in PI films with various water contents. When a dc field was applied to as-received PI films or water-treated PI films, positive and negative homo space charges were observed near the respective electrodes at 333 K. In dried PI films, the homo space charges were much reduced, and positive and negative hetero space charges in the bulk were clearly observed. The space charge amounts in water-treated PI films were smaller than in as-received ones, while the current density in water-treated PI film was larger than that in as-received one by two or more orders of magnitude. These suggest not only that the charge injection from the electrode is enhanced by absorbed water but also that absorbed water makes carriers mobile. The decay of space charge was also faster in water-treated PI than in as-received or dried one. This also supports the enhancement of apparent mobilities of carriers in PI by absorbed water.

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Energetic Disorder Dependence of Optimal Trap Depth in the Space Charge Field Formation for Photorefractivity

  • Lee, Choong-Keun;Park, Sun-Kyung;Yang, Min-O;Lee, Nam-Soo;Kim, Nak-Joong
    • Bulletin of the Korean Chemical Society
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    • 제28권3호
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    • pp.447-450
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    • 2007
  • Trap effects on the formation of space-charge field (SCF) associated with the photorefractivity of nonlinear optical polymers were studied by the Monte Carlo simulation using modified Gaussian disorder model. The charge transport dynamics influenced by the presence of trap molecules controls the formation of SCF via the charge distribution. Temporal behavior of SCF formation and SCF dependence on the trap depth are discussed in terms of the concentration and distribution of charges (holes and ionized acceptors) developed following illumination of light. The correlation of the trap depth and the energetic disorder is presented for an optimal efficiency for the SCF formation.

공간전하에 따른 전도전류의 변화에 대한 연구 (Study on the Effects of Space Charge on Conduction Current)

  • 최수일;이준호;김규언;김종민;황보승
    • 전기학회논문지
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    • 제59권12호
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    • pp.2225-2229
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    • 2010
  • In this study, we have investigated the effects of space charge on the conduction current with the variation of applied time of electric field in polymer insulators. We had also improved the PEA method, and then we could measure a simultaneously the space charge and the conduction current in insulators under the DC electric field. From this experiment, we have known the variation of conduction current due to the existence of space charge in XLPE1 and XLPE2.

공기층을 가진 저밀도 폴리에틸렌에서의 전도특성과 공간전하 효과 (Effects of Space Charge on Conduction Mechanism in Low density Polyethylene with Air Gap)

  • 박희웅;권윤혁;전승익;황보승;한민구
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1998년도 하계학술대회 논문집 D
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    • pp.1438-1440
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    • 1998
  • In this work, simultaneous measur of space charge and conduction current was c out in LDPE with air gap by Pulsed-Electro-Aco Method. Also, effect of long time charging at con electric field on the formation of space charge conduction was investigated. From the experim results. we knew that the homo space charge formed near the dielectric surfaces and moving the bulk of dielectric as the electric field elevated. This was related with the deep traps b carriers and de trapping by Poole-field lowering conduction current was coincident with the Pool emission. From the long time charging experimen obtained the results that the negative space was moving into the dielectric bulk as the cha continued and the positive space charge accumulated at upper surface of LDPE.

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HDPE/EVA혼합수지의 공간 전하 분포에 관한 연구 (A Study on Space Charge Distribution of HDPE Mixed with EVA)

  • 정의환;허준;윤재훈;임기조;이흥규
    • 전기학회논문지
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    • 제58권11호
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    • pp.2229-2235
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    • 2009
  • In this paper, each specimen blended at weight proportions of 80% HDPE to 20% EVA, 70% HDPE to 30% EVA, 60% HDPE to 40% EVA, and 50% HDPE to 50% EVA was manufactured respectively. The insulation performances of the proposed insulator were compared with conventional XLPE, main insulating material of CV cable on the basis of the investigation results of DC insulation performances. From the space charge density, electric field and potential profiles with raising DC voltage and time variation in HE82, distortion of electric field distribution was improved. As EVA mixed into the bulks acts as nucleation in crystallization process of HDPE, the size of spherulites became decreased and finally formed continuous network structure. Ultimately, it resulted from extinction of space charge in the interfacial region of spherulites.

LDPE에서 공간전하분포와 측정전류의 시간특성에 대한 수치해석 (Numerical Analysis about the Time Characteristics of Space Charge Distribution and Measured Current in LDPE)

  • 황보승;박대희;남석현;권윤혁;한민구
    • 대한전기학회논문지:전기물성ㆍ응용부문C
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    • 제49권9호
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    • pp.502-509
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    • 2000
  • In this paper in order to evaluat quantitavely the formation mechanism of space charge and its effects on the conduction characteristics in LDPE we have carried out the numerical analysis on the basis of experimental results of space charge distribution cathode field and current with time which had been simultaneously measured at applied field of 50kV/mm and room temperature. As the models for numerical analysis we employ the Richarson-Schottky theory for charge injection from electrode into LDPE and the band-tail conduction at crystalline regions and the hopping conduction by traps which mainly exist at the interface regions of crystalline-amorphous region for charge transport in LDPE. Futhermore in order to investigate the influence of physical parameters on the time characteristcs of space charge distribution and measured current we have changed the values of trap density activation energies for charge injection and transport and have analyzed their effects.

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금속/copper(Ⅱ)-phthalocyanine 계면에서의 Space Charge 연구 (Study of Space Charge of Metal/copper(Ⅱ)-phthalocyanine Interface)

  • 박미화;유현준;유형근;나승욱;김송희;이기진
    • 한국전기전자재료학회논문지
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    • 제18권4호
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    • pp.350-356
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    • 2005
  • We report the space charge and the surface potential of the interface between metal and copper(Ⅱ)-phthalocyanine(CuPc) thin films by measuring the microwave reflection coefficients S/sub 11/ of thin films using a near-field scanning microwave microscope(NSMM). CuPc thin films were prepared on Au and Al thin films using a thermal evaporation method. Two kinds of CuPc thin films were prepared by different substrate heating conditions; one was deposited on preheated substrate at 150。C and the other was annealed after deposition. The microwave reflection coefficients S/sub 11/ of CuPc thin films were changed by the dependence on grain alignment due to heat treatment conditions and depended on thickness of CuPc thin films. Electrical conductivity of interface between metal and organic CuPc was changed by the space charge of the interface. By comparing reflection coefficient S/sub 11/ we observed the electrical conductivity changes of CuPc thin films by the changes of surface potential and space charge at the interface.

PCB 절연체에서 전하 형성과 수분 흡수 (Water Absorption and Charge Formation in PCB)

  • 이정수;황종선
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2008년도 추계학술대회 논문집 전기설비전문위원
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    • pp.233-234
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    • 2008
  • We observed internal space charge behavior for two types of epoxy composites under dc electric fields to investigate the influence of water at high temperature. In the case of glass/epoxy specimen, homocharge is observed at water-treated specimen, and spatial oscillations become clearer in the water-treated specimens. Electric field in the vicinity of the electrodes shows the injection of homocharge. In aramid/epoxy specimens, heterocharge is observed at water-treated specimens, i.e. negative charge accumulates near the anode, while positive charge accumulates near the cathode. Electric field is enhanced just before each electrode. In order to further examine the mechanism of space charge formation, we have developed a new system that allows in situ space charge observation during ion migration tests at high temperature and high humidity. Using this in situ system.

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