Browsing by Author "Chang, DY"

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In situ compatibility of polystyrene and liquid crystalline polymer blends
(1996-12-01)
Chiou, YP
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Chang, DY
;
Chang, FC
;
應用化學系
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Department of Applied Chemistry
The styrene-glycidyl methacrylate (SG) copolymer can be used to compatibilize the immiscible and incompatible blends between polystyrene (PS) and liquid crystalline polymer (LCP) copolyester. The epoxy functional groups present in the SG copolymer can react with the carboxylic and/or the hydroxyl terminal groups of the LCP at interface to form the SG-g-LCP copolymer during melt processing. This in situ-formed graft copolymer tends to reside along the interface to reduce the interfacial tension in the melt state and to increase the interphase adhesion in the solid state. However, the compatibilized PS/LCP blends reduce the number of LCP fibrils formed and have a tendency to form droplet LCP domains. The overall mechanical properties, stiffness and toughness of the blends improved after compatibilization, but the extent of the improvement is not very significant. It appears that the gain from the adhesion enhancement is more than offset by the loss due to the reduction in LCP fibril formation. The ethyl triphenylsphosponium bromide catalyst can further improve the compatibility of the blends by increasing the rate of the graft reaction. Copyright (C) 1996 Elsevier Science Ltd.
Optimizing the match in weakly inverted MOSFET's by gated lateral bipolar action
(1996-05-01)
Chen, MJ
;
Ho, JS
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Chang, DY
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The on-chip n-type MOSFET current mirror circuit with different drawn gate widths and lengths has been fabricated, and has been characterized across the wafer with back gate slightly forward biased. The weakly inverted MOSFET device with a small back-gate forward bias represents equivalently the high-gain gated lateral bipolar transistor in low-level injection, Experimental results have exhibited a substantial improvement in the match of the drain current in weak inversion due to action of the gated lateral bipolar transistor, especially for the small size devices. The extensively measured mismatch of the weak inversion drain current has been successfully reproduced by an analytic statistical model with back-gate forward bias and device size both as input parameters. The experimentally extracted variations in process parameters such as the Rat band voltage and the body effect coefficient each have been found to follow the inverse square root of the device area, The mismatch model thus can serve as a quantitative design tool, and has been used to optimize the trade-off between the device area and the match with the forward back-gate bias as a parameter.