Browsing by Author "Chang, Y. M."

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Effect of layout on electromigration characteristics in copper dual damascene interconnects
(2014-10-05)
Cheng, Y. L.
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Chang, Y. M.
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Leu, Jihperng
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Bo, T. C.
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Wang, Y. L.
This study demonstrates that the electromigration (EM) behavior of dual damascene Cu lines is strongly affected by the layout which surrounded the tested EM lines, especially for Cu line below 0.10 mu m used for 40 nm or below technologies. The Cu EM lifetime declines as the number of local dummy lines increase, and the global dummy line density increases with the width of the Cu line below 0.063 mu m. This work presents mechanisms of layout effects that explain the EM characteristics and can be exploited to improve the layout effect. Therefore, not only the stressed Cu line structures, but also the surrounding layouts must to be considered in assessing EM reliability of a real IC circuit in 40 nm or below technology. (C) 2014 Elsevier B.V. All rights reserved.
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.
Picosecond Creation of Switchable Optomagnets from a Polar Antiferromagnet with Giant Photoinduced Kerr Rotations
(2019-08-30)
Sheu, Y. M.
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Chang, Y. M.
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Chang, C. P.
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Li, Y. H.
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Babu, K. R.
On-demand spin orientation with a long polarized lifetime and an easily detectable signal is the ultimate goal for spintronics. However, there still exists a trade-off between controllability and stability of spin polarization, awaiting a significant breakthrough. Here, we demonstrate switchable optomagnet effects in (Fe1-xZnx)(2)Mo3O8, from which we can obtain tunable magnetization (spanning from -40% to 40% of a saturated magnetization) that is created from zero magnetization in the antiferromagnetic state without magnetic fields. It is accomplishable by utilizing circularly polarized laser pulses to excite spin-flip transitions in polar antiferromagnets that have no spin canting, traditionally hard to control without very strong magnetic fields. The spin controllability in (Fe1-xZnx)(2)Mo3O8 originates from its polar structure that breaks the crystal inversion symmetry, allowing distinct on-site d-d transitions for selective spin flip. By chemical doping, we exploit the phase competition between antiferromagnetic and ferrimagnetic states to enhance and stabilize the optomagnet effects, which result in long-lived photoinduced Kerr rotations. The present study creating switchable giant optomagnet effects in polar antiferromagnets sketches a new blueprint for the function of antiferromagnetic spintronics.