Browsing by Author "Chang, HW"

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Dissociation dynamics of excited neutral fragments of gaseous SiCl4 following Si 2p and Cl 2p core-level excitations
(2005-09-01)
Chen, JM
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Lu, KT
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Lee, JM
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Ho, SC
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Chang, HW
State-specific dissociation dynamics for excited fragments of gaseous SiCl4 following Cl 2p and Si 2p core-level excitations were characterized by the dispersed UV/optical fluorescence spectroscopy. The core-to-Rydberg excitations at both Si 2p and Cl 2p edges lead to a noteworthy production of excited atomic fragments, neutral and ionic (Si-*,Si+*). In particular, the excited neutral atomic fragments Si-* are significantly reinforced. The core-to-valence excitation at the Si 2p edge generates an enhancement of excited molecular-ion SiCl4+. The experimental results provide deeper insight into the dissociation dynamics for excited neutral fragments of molecules via core-level excitation.
Existence of invariant series consecutive-k-out-of-n : G systems
(1999-09-01)
Chang, HW
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Hwang, FK
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應用數學系
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資訊工程學系
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Department of Applied Mathematics
A consecutive-k-out-of-n:G line has an invariant optimal assignment iff k less than or equal to n less than or equal to 2k. This paper studies a system consisting of consecutive-k(i)-out-of-n(i) :G lines with k(i) less than or equal to n(i) less than or equal to 2k(i), completely characterizes the existence of an invariant optimal assignment.
Formation of interfacial layer during reactive sputtering of hafnium oxide
(2003-06-15)
Tsui, BY
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Chang, HW
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Hafnium oxide is one of the most promising high dielectric constant materials to replace silicon dioxide as the gate dielectric. To take the advantages of high dielectric constant of HfO2 thoroughly, the relatively low dielectric constant interfacial layer must be controlled carefully. In this work, the formation of an interfacial SiO2 layer at the HfO2/Si interface was studied comprehensively. It is observed that during reactive sputtering deposition of the HfO2 layer, a very thick interfacial SiO2 layer, thicker than 3 nm, would be grown. O-radical signals, instead of O-2-radicl signals, are detected in the sputtering chamber. An O-radical enhanced oxidation model is proposed to explain such an unusual thick SiO2 layer. The adoption of a two-step deposition method, the thickness of interfacial SiO2 layer can be reduced only if the bottom Hf layer is thicker than 5 nm. However, the reduction of effective oxide thickness would be limited. Reoxidation of Hf film sounds a better choice. A 1.0-1.5-nm-thick interfacial SiO2 layer is still observed. This implies that the traced oxygen in the sputtering chamber plays a critical role on the formation of the interfacial layer. It is thus concluded that reactive sputtering is not a suitable method to prepare a HfO2 layer with a negligible interfacial SiO2 layer. Reoxidation of Hf film is a better choice, but the oxygen content in the sputtering chamber must be well controlled. (C) 2003 American Institute of Physics.
Rare-event component importance for the consecutive-k system
(2002-03-01)
Chang, HW
;
Hwang, FK
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應用數學系
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Department of Applied Mathematics
Various indices of component importance with respect to system reliability have been proposed. The most popular one is the Birnbaum importance. In particular, a special case called uniform Birnbaum importance in which all components have the same reliability p has been widely studied for the consecutive-k system. Since it is not easy to compare uniform Birnbaum importance, the literature has looked into the case p = 1/2, p --> 1, or p greater than or equal to 1/2. In this paper, we look into the case p --> 0 to complete the spectrum of examining Birnbaum importance over the whole range of p. (C) 2002 Wiley Periodicals, Inc.
The structural Birnbaum importance of consecutive-k systems
(2002-06-01)
Chang, HW
;
Chen, RJ
;
Hwang, FK
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應用數學系
;
資訊工程學系
This paper is concerned with three types of structural Birnbaum importance of components in a consecutive-k system. We accomplish the following three tasks: (i) Survey existing results, including pointing out results claimed but proofs are incomplete. (ii) Give some new results and useful lemmas. (iii) Observe what are still provable and what are not with the help of extensive computing.