Browsing by Author "Wu, S. -C."

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Effects of stress relief coupled with reduced EBW energy on flow formed maraging steel weldment
(2008-07-01)
Lee, Y. -J.
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Wu, S. -C.
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Chang, J. -L.
;
Chou, C. -P.
;
Lee, I. -K.
A flow formed C-250 maraging steel tubing was welded by electron beam welded (EBW) process and subsequently age hardened. Conventional EB welding with high energy input had resulted in seriously inadequate percentage elongation of the weldment. With an additional prewelding stress relief treatment and EBW with a lower energy input, the elongation of the weldment showed significant improvement after being treated with age hardening. It was found that the tensile strength was increased by 12% and the percentage elongation was remarkably increased by 92%.
Multi-level control of conductive nano-filament evolution in HfO2 ReRAM by pulse-train operations
(2014-06-07)
Zhao, L.
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Chen, H. -Y.
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Wu, S. -C.
;
Jiang, Z.
;
Yu, S.
Precise electrical manipulation of nanoscale defects such as vacancy nano-filaments is highly desired for the multi-level control of ReRAM. In this paper we present a systematic investigation on the pulse-train operation scheme for reliable multi-level control of conductive filament evolution. By applying the pulse-train scheme to a 3 bit per cell HfO2 ReRAM, the relative standard deviations of resistance levels are improved up to 80% compared to the single-pulse scheme. The observed exponential relationship between the saturated resistance and the pulse amplitude provides evidence for the gap-formation model of the filament-rupture process.
Strain study of self-assembled InAs quantum dots by ion channeling technique
(2006-11-15)
Wang, Hsing-Yeh
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Lee, Chien-Ping
;
Niu, H.
;
Chen, C. H.
;
Wu, S. -C.
Ion channeling technique using MeV C++ ions was used to study strain in self-assembled InAs quantum dots (QDs) buried in GaAs matrix. Because of the use of heavy ions, we were able to observe an angular shift in the angular scan of the In signal relative to that of the Ga/As signal. This provided a direct evidence that the InAs lattice is larger than that of GaAs in the growth direction. Combining the channeling results in [100] and [110] directions and the photoluminescence emission spectrum, we conclude that the InAs QDs are under tensile strain in the growth direction and have the same lattice constant as that of GaAs in the lateral direction. Thermal annealing causes the strain to relax, first in the growth direction and then in the lateral direction as the annealing temperature increases. The photoluminescence spectra of the QDs before and after annealing indicate, however, that composition intermixing also takes place during annealing and is the dominant factor in determining the band gap energy of the QDs. (c) 2006 American Institute of Physics.