Browsing by Author "Yeh, C. C."

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Improvement of lumen efficiency in white light-emitting diodes with air-gap embedded package
(2012-05-01)
Chen, H. C.
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Chen, K. J.
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Lin, C. C.
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Wang, C. H.
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Yeh, C. C.
In this paper, white light-emitting diodes (LEDs) with air-gap embedded package were proposed and fabricated by a simple method including pulsed spray coating. The lumen efficiency of air-gap embedded LED was enhanced by 8.8% at driving current of 350 mA, compared to conventional remote phosphor white LED. This improvement was due to the enhanced utilization of blue and yellow rays, which were confirmed by pulse current-dependent correlated color temperature (CCT). The utilization efficiency of blue rays was enhanced by 12.4% due to the embedded air-gap layer. The simulation results performed by Monte-Carlo ray tracing method agreed with our experiments, which showed enhancement in lumen efficiency and similar CCT. Finally, the electric field intensity versus different thickness for air-gap and no air-gap embedded white LED was calculated to check the incident blue rays trapped in phosphor layer. Crown Copyright (C) 2012 Published by Elsevier Ltd. All rights reserved.
Insight of stress effect on the ONO stack layer in a SONOS-type flash memory cell
(2006)
Yeh, C. C.
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Liao, Y. Y.
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Wang, Tahui
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Tsai, W. J.
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Lu, T. C.
The stress effect on the ONO stack layer in a two-bit SONOS-type memory cell is investigated. Our results show that P/E cycles induced stress will generate extra nitride, oxide, and interface traps in the ONO stack layer. Besides, these stress created traps are unstable and will be annealed by additional thermal treatment. Storage electrons escape from stress-created nitride and oxide traps and the trap annealing effects are root causes of charge loss in a SONOS cell.
Investigation of charge loss in cycled NBit cells via field and temperature accelerations
(2006)
Tsai, W. J.
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Zous, N. K.
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Chen, H. Y.
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Liu, Lenvis
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Yeh, C. C.
In nitride storage flash memories, the high-V-T state retention loss induced by field and temperature acceleration is compared between single cells and products. Our result reveals that the charge loss path is the same no matter which accelerating methods is used. The traps created at the bottom oxide during P/E cycling provide such leak paths. In addition, the annealing of interface states would play a role in the V-T loss during high-temperature bake.