Browsing by Author "Lee, S. W."

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A transition of three to two dimensional Si growth on Ge (100) substrate
(2012-12-15)
Tu, W. -H.
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Lee, C. -H.
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Chang, H. T.
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Lin, B. -H.
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Hsu, C. -H.
For the initial growth of Si on Ge, three-dimensional Si quantum dots grown on the Ge surface were observed. With increasing Si thickness, the Si growth changes from three-dimensional to two-dimensional growth mode and the dots disappear gradually. Finally, the surface is smooth with the roughness of 0.26 nm, similar to the original Ge substrate, when 15 nm Si is deposited. More Ge segregation on the wetting layer leads to more open sites to increase the subsequent Si growth rate on the wetting layer than on the Si dots. The in-plane x-ray diffraction by synchrotron radiation is used to observe the evolution of tensile strain in the Si layer grown on Ge (100) substrate. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4770408]
Computational Modeling of a Lightweight Composite Space Reflector using Geometrically Nonlinear Solid Shell Elements
(2008-08-01)
Lee, K.
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Wu, C. T.
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Clarke, G. V.
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Lee, S. W.
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A geometrically nonlinear finite element analysis of a low area] density composite space reflector is conducted under static conditions and the results are compared with independently carried out experimental data. The finite element analysis is based on an assumed strain formulation of a geometrically nonlinear nine-node solid shell element. Numerical results are in good agreement with experimental data. This demonstrates the effectiveness of the present solid shell element approach when applied to the analysis of highly flexible space structures. The results of numerical analysis and the experimental data reported in the present paper provide a benchmark for future investigations on the modeling and analysis of geometrically nonlinear composite shell structures via computational tools.
Enhanced growth of low-resistivity titanium silicides on epitaxial Si(0.7)Ge(0.3) on (001)Si with a sacrificial amorphous Si interlayer
(2010-10-01)
Wu, W. W.
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Wang, C. W.
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Chen, K. N.
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Cheng, S. L.
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Lee, S. W.
Enhanced growth of low-resistivity self-aligned titanium silicides on epitaxial Si(0.7)Ge(0.3) with a sacrificial amorphous Si (a-Si) interlayer has been achieved. The a-Si layer with appropriate thickness was found to prevent Ge segregation, decrease the growth temperature, as well as maintain the interface flatness and morphological stability in forming low-resistivity C54-TiSi(2) on Si(0.7)Ge(0.3) grown by molecular beam epitaxy. The process promises to be applicable to the fabrication of high-speed Si-Ge devices. (C) 2010 Published by Elsevier B.V.
Enhanced growth of low-resistivity titanium silicides on epitaxial Si0.7Ge0.3 on (001)Si with a sacrificial amorphous Si interlayer
(2010-10-01)
Wu, W. W.
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Wang, C. W.
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Chen, K. N.
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Cheng, S. L.
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Lee, S. W.
Enhanced growth of low-resistivity self-aligned titanium silicides on epitaxial Si0.7Ge0.3 with a sacrificial amorphous Si (a-Si) interlayer has been achieved. The a-Si layer with appropriate thickness was found to prevent Ge segregation, decrease the growth temperature, as well as maintain the interface flatness and morphological stability in forming low-resistivity C54-TiSi2 on Si0.7Ge0.3 grown by molecular beam epitaxy. The process promises to be applicable to the fabrication of high-speed Si-Ge devices. (C) 2010 Published by Elsevier B.V.
Ni silicide formation on epitaxial Si(1-y)C(y)/(001) layers
(2010-10-01)
Lee, S. W.
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Huang, S. H.
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Cheng, S. L.
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Chen, P. S.
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Wu, W. W.
The formation of Ni silicides on Si(1 - y)C(y) (y=0.01 and 0.018) epilayers grown on Si(001) has been investigated. The presence of C atoms was found to significantly retard the growth kinetics of NiSi and enhances the thermal stability of thin NiSi films. For Ni(11 nm)/Si(0.982)C(0.018) samples, the process window of NiSi was shifted and extended to 450-700 degrees C. Moreover, there was an additional strain introduced into the Si(1 - y)C(y) epilayers during Ni silicidation. This work shows the potential of Ni silicidation on Si(1y)C(y) for device applications. (C) 2010 Elsevier B.V. All rights reserved.
Ni silicide formation on epitaxial Si1-yCy/(001) layers
(2010-10-01)
Lee, S. W.
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Huang, S. H.
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Cheng, S. L.
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Chen, P. S.
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Wu, W. W.
The formation of Ni silicides on Si1 - yCy (y=0.01 and 0.018) epilayers grown on Si(001) has been investigated. The presence of C atoms was found to significantly retard the growth kinetics of NiSi and enhances the thermal stability of thin NiSi films. For Ni(11 nm)/Si0.982C0.018 samples, the process window of NiSi was shifted and extended to 450-700 degrees C. Moreover, there was an additional strain introduced into the Si1 - yCy epilayers during Ni silicidation. This work shows the potential of Ni silicidation on Si1yCy for device applications. (C) 2010 Elsevier B.V. All rights reserved.
SiGe nanorings by ultrahigh vacuum chemical vapor deposition
(2009-04-06)
Lee, C. -H.
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Shen, Y. -Y.
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Liu, C. W.
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Lee, S. W.
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Lin, B. -H.
Formation of SiGe nanorings from Si capped Si(0.1)Ge(0.9) quantum dots (QDs) grown at 500 degrees C by ultrahigh vacuum chemical vapor deposition was investigated. SiGe nanorings have average diameter, width, and depth of 185, 30, and 9 nm, respectively. Based on both Raman and x-ray diffraction results, the formation of SiGe nanorings can be attributed to Ge outdiffusion from central SiGe QDs during in situ annealing. Moreover, the depth of SiGe nanorings can be controlled by Si cap thickness. The Si cap is essential for nanorings formation.