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Shou-gwo Wuu - One of the best experts on this subject based on the ideXlab platform.

  • A Comparison of Behaviors between Hydrogenated/Unhydrogenated Polysilicon Thin Film Transistors under Electric Stress
    Japanese Journal of Applied Physics, 2000
    Co-Authors: Dun-nian Yaung, Kan-yuan Lee, Y.k. Fang, Shou-gwo Wuu, Kuo-ching Hwang, M.s. Liang
    Abstract:

    The effects and kinetics of Electric Stress on hydrogenated/unhydrogenated polysilicon thin-film transistors (poly-TFTs) have been investigated. The postStress characteristics of TFTs depend not only on the Stress condition but also on the hydrogenation process. Under off-state Stress conditions (Vgs=0 V and Vds=-15 V), the postStress subthreshold swing and on-current of unhydrogenated TFTs are improved due to the annealing effect of donor-like traps, which is caused by tunneling electrons/captured holes interaction. While under on-state Stress conditions (Vgs=-20 V and Vds=-15 V), these characteristics are first improved, then deteriorated because of electron trapping in the gate oxide and carrier-induced metastable defects in the channel. The postStress characteristics will not be improved if the trap states have been previously removed by hydrogenation. In addition, we found that the postStress characteristics under off-state Stress conditions are not changed after thermal annealing at 250°C for 30 min, while the metastable defects and electron trapping under on-state Stress conditions can be easily annealed after thermal treatment.

  • The anomalous behavior of hydrogenated/unhydrogenated polysilicon thin-film transistors under Electric Stress
    IEEE Electron Device Letters, 1997
    Co-Authors: Kan-yuan Lee, Y.k. Fang, C.w. Chen, K.c. Huang, M.s. Liang, Shou-gwo Wuu
    Abstract:

    The characteristics of high-temperature processed thin-film transistors (TFT's) with/without plasma hydrogenation under the Stress condition of V/sub ds/=-15 V and V/sub gs/=0 V have been investigated and compared. It is found that, after Stress, the subthreshold swing is greatly improved for unhydrogenated TFT's but not for hydrogenated TFT's. Also, the off-state current is deteriorated for unhydrogenated TFT's but, on the contrary, it is improved for hydrogenated TFT's. A model that takes the effect of hydrogen passivation into account is proposed to interpret the anomalous behavior of TFT's under Electric Stress.

George Chen - One of the best experts on this subject based on the ideXlab platform.

  • Space charge and charge trapping characteristics of cross-linked polyethylene subjected to ac Electric Stresses
    Journal of Physics D: Applied Physics, 2006
    Co-Authors: Y L Chong, George Chen, Hiroaki Miyake, Yasuhiro Tanaka, K Matsui, Tatsuo Takada
    Abstract:

    This paper reports on the result of space charge evolution in cross-linked polyethylene (XLPE) planar samples approximately 220 µm thick. The space charge measurement technique used in this study is the pulsed electroacoustic method. There are two phases to this experiment. In the first phase, the samples were subjected to dc 30 kVdc mm −1 and ac (sinusoidal) Electric Stress levels of 30 kVpk mm −1 at frequencies of 1, 10 and 50 Hz ac. In addition, ac space charge under 30 kVrms mm −1 and 60 kVpk mm −1 Electric Stress at 50 Hz was also investigated. The volts-off results showed that the amount of charge trapped in XLPE sample under dc Electric Stress is significantly bigger than samples under ac Stress even when the applied ac Stresses are substantially higher. The second phase of the experiment involves studying the dc space charge evolution in samples that were tested under ac Stress during the first phase of the experiment. Ac ageing causes positive charge to become more dominant over negative charge. It was also discovered that ac ageing creates deeper traps, particularly for negative charge. This paper also gives a brief overview of the data processing methods used to analyse space charge under ac Electric Stress. (Some figures in this article are in colour only in the electronic version)

  • Space charge measurement in polymer insulated power cables using flat ground electrode PEA
    IEE Proceedings - Science Measurement and Technology, 2003
    Co-Authors: George Chen
    Abstract:

    Data processing methods used to accurately determine the space charge and Electric Stress distributions in DC power cables using the pulsed electroacoustic (PEA) system are described. Due to the coaxial geometry and the thick-walled insulation of highvoltage cables, factors such as divergence, attenuation and dispersion of the propagated acoustic pressure wave in the PEA can strongly influence the resultant measurements. These factors are taken into account ensuring accurate measurements to be made. Most importantly, a method is presented to determine the Electric Stress profile across the insulation due to both the divergent applied field and that as a consequence of trapped charge in the bulk of the insulating material. Results of spacecharge measurements and the corresponding derived Electric Stress distributions in XLPE DC cables are presented.

  • Space charge formation under dc conditions and its influence on Electric Stress profile after voltage reversal in XLPE cable
    2003
    Co-Authors: George Chen
    Abstract:

    The paper presents the space charge evolution in a cross-linked polyethylene (XLPE) power cable under dc Stress and its influence on the Electric Stress distribution after the voltage reversal. Due to the relatively high stability of the space charge formed in previous voltage polarity, the Electric Stress profile across the insulation was severely distorted during the voltage reversal process.

  • Space charge measurements in XLPE insulation under 50 Hz ac Electric Stress
    Eighth International Conference on Dielectric Materials Measurements and Applications, 2000
    Co-Authors: George Chen, A.e. Davies, R.n. Hampton, S. Hobdell, S.g. Swingler, S. J. Sutton
    Abstract:

    Space charge is believed to play an important role in Electrical ageing of polymeric insulation, particularly where Electric tree initiation is the dominant cause of premature failure of the material. However, space charge trapping and dynamics under ac operating conditions are not fully understood. This paper reports on an on-going investigation into the measurement of space charge in cross-linked polyethylene (XLPE) insulation subjected to 50 Hz ac Electric Stress. This paper describes the main features of the laser induced pressure pulse (LIPP) method used for the ac space charge measurements. Preliminary results of the charge and Electric Stress distributions in as received and degassed XLPE plaque samples Stressed at ac Stress of up to 30 kV/mm/sub peak/ are also presented.

  • Space charge measurements in power cables using a modified PEA system
    Eighth International Conference on Dielectric Materials Measurements and Applications, 2000
    Co-Authors: George Chen, A.e. Davies, J.g. Head
    Abstract:

    This paper briefly describes the signal processing to determine the space charge and Electric Stress distributions using the newly developed pulsed electro-acoustic (PEA) system for use on power cables. Due to the coaxial geometry and the thick walled insulation, factors such as divergence, attenuation and dispersion of the propagated acoustic pressure wave can strongly influence the resultant measurements. This paper describes the development of a data processing technique, which allows for the factors previously mentioned, ensuring accurate measurements to be made. Most importantly, a method is presented to determine the Electric Stress profile across the insulation due to both the divergent applied field and consequence of trapped charge in the material. Some preliminary results of space charge measurements and the corresponding derived Electric Stress distributions in XLPE cables are also given.

Kan-yuan Lee - One of the best experts on this subject based on the ideXlab platform.

  • A Comparison of Behaviors between Hydrogenated/Unhydrogenated Polysilicon Thin Film Transistors under Electric Stress
    Japanese Journal of Applied Physics, 2000
    Co-Authors: Dun-nian Yaung, Kan-yuan Lee, Y.k. Fang, Shou-gwo Wuu, Kuo-ching Hwang, M.s. Liang
    Abstract:

    The effects and kinetics of Electric Stress on hydrogenated/unhydrogenated polysilicon thin-film transistors (poly-TFTs) have been investigated. The postStress characteristics of TFTs depend not only on the Stress condition but also on the hydrogenation process. Under off-state Stress conditions (Vgs=0 V and Vds=-15 V), the postStress subthreshold swing and on-current of unhydrogenated TFTs are improved due to the annealing effect of donor-like traps, which is caused by tunneling electrons/captured holes interaction. While under on-state Stress conditions (Vgs=-20 V and Vds=-15 V), these characteristics are first improved, then deteriorated because of electron trapping in the gate oxide and carrier-induced metastable defects in the channel. The postStress characteristics will not be improved if the trap states have been previously removed by hydrogenation. In addition, we found that the postStress characteristics under off-state Stress conditions are not changed after thermal annealing at 250°C for 30 min, while the metastable defects and electron trapping under on-state Stress conditions can be easily annealed after thermal treatment.

  • The anomalous behavior of hydrogenated/unhydrogenated polysilicon thin-film transistors under Electric Stress
    IEEE Electron Device Letters, 1997
    Co-Authors: Kan-yuan Lee, Y.k. Fang, C.w. Chen, K.c. Huang, M.s. Liang, Shou-gwo Wuu
    Abstract:

    The characteristics of high-temperature processed thin-film transistors (TFT's) with/without plasma hydrogenation under the Stress condition of V/sub ds/=-15 V and V/sub gs/=0 V have been investigated and compared. It is found that, after Stress, the subthreshold swing is greatly improved for unhydrogenated TFT's but not for hydrogenated TFT's. Also, the off-state current is deteriorated for unhydrogenated TFT's but, on the contrary, it is improved for hydrogenated TFT's. A model that takes the effect of hydrogen passivation into account is proposed to interpret the anomalous behavior of TFT's under Electric Stress.

K. Fukunaga - One of the best experts on this subject based on the ideXlab platform.

  • Millisecond time-range analysis of space-charge distribution and electroluminescence in insulating polymers under transient Electric Stress
    Journal of Applied Physics, 2005
    Co-Authors: M. Fukuma, Gilbert Teyssedre, Christophe Laurent, K. Fukunaga
    Abstract:

    The combined analysis of the space charge and electroluminescence (EL) in insulating polymers provides useful information on charge transport and energy dissipation. We are particularly interested in defining critical transport regimes leading to energy releases potentially harmful for the material. These critical regimes can be characterized by investigating the internal charge distribution when electroluminescence is detected. The dc case has been adequately covered: however, very few results are reported involving transient Electric Stress because its investigation needs a very fast space-charge detection setup. We have carried out such an analysis in the case of low-density polyethylene and polyethylene naphthalate (PEN) films by using fast acquisition techniques for both, the space-charge profile (resolution of 40μs in time and 15μm in depth) and the electroluminescence acquisition (250μs time resolution). The films were subjected to a voltage ramp up to a targeted level followed by a stabilization a...

  • in PE and PEN under transient Electric Stress Millisecond-time range analysis of space charge distribution and electroluminescence
    2004
    Co-Authors: M. Fukuma, Gilbert Teyssedre, K. Fukunaga, C. Lauren, I Matsue
    Abstract:

    The combined analysis of space charge and electroluminescence in insulating polymers provides useful information on charge transport and energy dissipation. We are particularly interested in defining critical transport regimes leading to energy release in a range that is potentially harmful for the material. These critical regimes can he characterized by investigating the internal charge distribution when electroluminescence is detected. If the DC case has been treated recently, very few results are reported concerning transient Electric Stress because the experiment needs ultra-fast space charge detection set- up. We have carried out such analysis when low density polyethylene and polyethylene naphthalate films are submitted to transient voltages of 50 ms in duration, by using fast acquisition techniques for both space charge profile (50 ps time resolution) and electroluminescence acquisition (250 ps time resolution).

  • Millisecond-time range analysis of space charge distribution and electroluminescence in PE and PEN under transient Electric Stress
    The 17th Annual Meeting of the IEEE Lasers and Electro-Optics Society 2004. LEOS 2004., 1
    Co-Authors: M. Fukuma, Gilbert Teyssedre, K. Fukunaga, Christophe Laurent
    Abstract:

    The combined analysis of space charge and electroluminescence in insulating polymers provides useful information on charge transport and energy dissipation. We are particularly interested in defining critical transport regimes leading to energy release in a range that is potentially harmful for the material. These critical regimes can be characterized by investigating the internal charge distribution when electroluminescence is detected. If the DC case has been treated recently, very few results are reported concerning transient Electric Stress because the experiment needs an ultra-fast space charge detection setup. We have carried out such an analysis when low density polyethylene and polyethylene naphthalate films are submitted to transient voltages of 50 ms in duration, by using fast acquisition techniques for the both space charge profile (50 /spl mu/s time resolution) and electroluminescence acquisition (250 /spl mu/s time resolution).

M.s. Liang - One of the best experts on this subject based on the ideXlab platform.

  • A Comparison of Behaviors between Hydrogenated/Unhydrogenated Polysilicon Thin Film Transistors under Electric Stress
    Japanese Journal of Applied Physics, 2000
    Co-Authors: Dun-nian Yaung, Kan-yuan Lee, Y.k. Fang, Shou-gwo Wuu, Kuo-ching Hwang, M.s. Liang
    Abstract:

    The effects and kinetics of Electric Stress on hydrogenated/unhydrogenated polysilicon thin-film transistors (poly-TFTs) have been investigated. The postStress characteristics of TFTs depend not only on the Stress condition but also on the hydrogenation process. Under off-state Stress conditions (Vgs=0 V and Vds=-15 V), the postStress subthreshold swing and on-current of unhydrogenated TFTs are improved due to the annealing effect of donor-like traps, which is caused by tunneling electrons/captured holes interaction. While under on-state Stress conditions (Vgs=-20 V and Vds=-15 V), these characteristics are first improved, then deteriorated because of electron trapping in the gate oxide and carrier-induced metastable defects in the channel. The postStress characteristics will not be improved if the trap states have been previously removed by hydrogenation. In addition, we found that the postStress characteristics under off-state Stress conditions are not changed after thermal annealing at 250°C for 30 min, while the metastable defects and electron trapping under on-state Stress conditions can be easily annealed after thermal treatment.

  • The anomalous behavior of hydrogenated/unhydrogenated polysilicon thin-film transistors under Electric Stress
    IEEE Electron Device Letters, 1997
    Co-Authors: Kan-yuan Lee, Y.k. Fang, C.w. Chen, K.c. Huang, M.s. Liang, Shou-gwo Wuu
    Abstract:

    The characteristics of high-temperature processed thin-film transistors (TFT's) with/without plasma hydrogenation under the Stress condition of V/sub ds/=-15 V and V/sub gs/=0 V have been investigated and compared. It is found that, after Stress, the subthreshold swing is greatly improved for unhydrogenated TFT's but not for hydrogenated TFT's. Also, the off-state current is deteriorated for unhydrogenated TFT's but, on the contrary, it is improved for hydrogenated TFT's. A model that takes the effect of hydrogen passivation into account is proposed to interpret the anomalous behavior of TFT's under Electric Stress.