Browsing by Author "Hsieh, Y. C."

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An AlGaAs/InGaAs HEMT Grown on Si Substrate with Ge/GexSi1-x Metamorphic Buffer Layers
(2008)
Chang, Edward Yi
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Lin, Yueh-Chin
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Hsiao, Yu-Lin
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Hsieh, Y. C.
;
Chang, Chia-Yuan
An AlGaAs/InGaAs HEMT grown on Si substrate with Ge/GexSi1-x buffer is demonstrated. The Ge/GexSi1-x metamorphic buffer layer used in this structure was only 1.0 mu m thick. The electron mobility in the In0.18Ga0.82As channel of the HEMT sample was 3,550 cm(2)/Vs. After fabrication, the HEMT device demonstrated a saturation current of 150 mA/mm and a maximum transconductance of 155 mS/mm. The well behaved characteristics of the HEMT device on the Si substrate are believed to be due to the very thin buffer layer achieved and the lack of the antiphase boundaries (APBs) formation and Ge diffusion into the GaAs layers. Index Terms: HEW GaAs on Si, SiGe buffer layer
Growth of very-high-mobility AlGaSb/InAs high-electron-mobility transistor structure on si substrate for high speed electronic applications
(2007-01-08)
Lin, Y. C.
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Yamaguchi, H.
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Chang, E. Y.
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Hsieh, Y. C.
;
Ueki, M.
The growth of the AlGaSb/InAs high-electron-mobility transistor (HEMT ) epitaxial structure on the Si substrate is investigated. Buffer layers consisted of UHV/chemical vapor deposited grown Ge/GeSi and molecular beam epitaxy-grown AlGaSb/AlSb/GaAs were used to accommodate the strain induced by the large lattice mismatch between the AlGaSb/InAs HEMT structure and the Si substrate. The crystalline quality of the structure grown was examined by x-ray diffraction, transmission electron microscopy, and atomic force microscopy. Finally, very high room-temperature electron mobility of 27 300 cm(2) /V s was achieved. It is demonstrated that a very-high-mobility AlGaSb/InAs HEMT structure on the Si substrate can be achieved with the properly designed buffer layers. (c) 2007 American Institute of Physics.
Improved electrochemical performances by carbon nanocapsules as an electrocatalyst support for direct methanol fuel cells
(2009-02-01)
Chang, Y. M.
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Hsieh, Y. C.
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Wu, R. W.
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材料科學與工程學系
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Department of Materials Science and Engineering
The carbon nanocapsules (CNCs) were evaluated as a catalyst support for direct methanol fuel cells (DMFC). The gas diffusion electrodes (GDE) of CNCs exhibited smaller pores, higher electrochemical surface areas, lower charge transfer resistances, and reduced resistivities as compared to those of Vulcan XC72R (VXC72R). The observed superiorities were attributed to their narrow size distributions and graphene layers on the perimeters. In addition, binary PtRu nanoparticles were synthesized and impregnated to the CNCs and VXC72R. The images from the transmission electron microscope indicated that the PtRu nanoparticles were dispersed better in the CNCs, resulting in relatively reduced particle sizes and greater uniformity. In cyclic voltammery, the PtRu/CNCs catalyzed GDEs revealed significantly larger current responses with lower onset potentials as compared to those of PtRu/VXC72R. Our results confirm the superb characteristic of CNCs as an electrocatalyst support for DMFC applications. (c) 2008 Elsevier B.V. All rights reserved.
Levosimendan shortens action potential duration, decreases alternans threshold and prevents ventricular arrhythmia during therapeutic hypothermia in isolated rabbit hearts
(2019-10-01)
Hsieh, Y. C.
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Li, C. H.
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Liao, Y. C.
;
Lin, J. C.
;
Weng, C. J.
Self-assembled In0.22Ga0.78As quantum dots grown on metamorphic GaAs/Ge/SixGe1-x/Si substrate
(2006-09-15)
Hsieh, Y. C.
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Chang, E. Y.
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Luo, G. L.
;
Chen, S. H.
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Biswas, Dhrubes
Self-assembled In0.22Ga0.78As quantum dots (QDs) grown on Si substrate with Ge/SiGe as buffer layer grown by metal organic vapor phase epitaxy were investigated. Transmission electron microscopy and atomic force microscopy images were used to observe the size and space distribution of the In0.22Ga0.78As QDs grown on the GaAs/Ge/GeSi/Si layer structure. The influence of the growth temperature on the QDs size and density distribution was investigated. For QDs grown at 450 degrees C, the density of the In0.22Ga0.78As dots was estimated to be 1x10(11) cm(-2) and the In0.22Ga0.78As QDs thickness was 5 ML (monolayer) thick. (c) 2006 American Institute of Physics.
Use of Si+ pre-ion-implantation on Si substrate to enhance the strain relaxation of the GexSi1-x metamorphic buffer layer for the growth of Ge layer on Si substrate
(2007-02-19)
Hsieh, Y. C.
;
Chang, E. Y.
;
Luo, G. L.
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Pilkuhn, M. H.
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Tang, S. S.
Si+ pre-ion-implantation combined with a GexSi1-x metamorphic buffer structure for the growth of Ge layer on Si substrate is proposed. Enhanced strain relaxation of the GexSi1-x metamorphic buffer layer on Si substrate was achieved due to the introduction of the point defects by heavy dose Si+ pre-ion-implantation. Because of the strain relaxation enhancement and the interface blocking of the dislocations in the GexSi1-x metamorphic buffer structure, the total thickness of the buffer layers was only 0.45 mu m. No cross-hatch pattern was observed on the Ge surface and the dislocation density for the top Ge film was only 7.6x10(6) cm(-2). (c) 2007 American Institute of Physics.