Browsing by Author "Liu, C. 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]
Carrier gas effects on the SiGe quantum dots formation
(2008-07-30)
Lee, C. -H.
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Yu, C. -Y.
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Lin, C. M.
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Liu, C. W.
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Lin, H.
SiGe quantum dots (QDs) grown by ultra-high vacuum chemical vapor deposition using H(2) and He carrier gases are investigated and compared. SiGe QDs using He carrier gas have smaller dot size with a better uniformity in terms of dot height and dot base as compared to the H(2) carrier gas. There is a higher Ge composition and less compressive strain in the SiGe QDs grown in He than in H(2) as measured by Raman spectroscopy. The Ge content is higher for He growth than H(2) growth due to hydrogen induced Si segregation and the lower interdiffusivity caused by the more strain relaxation in the He-grown SiGe dots. The photoluminescence also confirms more compressive strain for H(2) growth than He growth. Hydrogen passivation and Ge-H cluster formation play an important role in the QDs growth. (C) 2008 Elsevier B. V. All rights reserved.
Electrical and Optical Properties of a Single Sb(2)Se(3) Nanorod
(2009-06-01)
Ko, T. Y.
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Yang, C. H.
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Sun, K. W.
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Chang, H. W.
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Sarkar, B.
In this paper we present the methods to chemically synthesize the Sb(2)Se(3) nanorods and study the electrical and optical properties of a single Sb(2)Se(3) nanorod with an average size of 70 nm in diameter and a length of about 1 mu m to 2 mu m. The techniques we devised can immobilize and allocate a single nano-object on an electron beam (E-beam) patterned smart substrate. It can also overcome the limitation of the spatial resolution of conventional optical techniques (similar to 1 mu m) to obtain optical spectroscopy in an individual nano-object less than 100 nm in size. We also demonstrate the techniques in using E-beam defined metallic coordination markers as electrodes to measure the conductance of a single Sb(2)Se(3) nanorod.
Electrical and Optical Properties of a Single Sb2Se3 Nanorod
(2009-06-01)
Ko, T. Y.
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Yang, C. H.
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Sun, K. W.
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Chang, H. W.
;
Sarkar, B.
In this paper we present the methods to chemically synthesize the Sb2Se3 nanorods and study the electrical and optical properties of a single Sb2Se3 nanorod with an average size of 70 nm in diameter and a length of about 1 mu m to 2 mu m. The techniques we devised can immobilize and allocate a single nano-object on an electron beam (E-beam) patterned smart substrate. It can also overcome the limitation of the spatial resolution of conventional optical techniques (similar to 1 mu m) to obtain optical spectroscopy in an individual nano-object less than 100 nm in size. We also demonstrate the techniques in using E-beam defined metallic coordination markers as electrodes to measure the conductance of a single Sb2Se3 nanorod.
Performance enhancement of the nMOSFET low-noise amplifier by package strain
(2007-01-01)
Hua, W. -C.
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Chang, H. -L.
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Wang, T.
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Lin, C. -Y
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Lin, C. -P.
The package strain improves the noise figure (NF) of the low-noise amplifier (LNA). The maximum noise reduction is similar to 0.53 dB (13%) at the operating frequency of 2.4 GHz under the biaxial tensile strain of 0.037%. The NIT reduction of the strained LNA is mainly due to the enhanced transconductance and cutoff frequency of the individual nMOSFET device under the same strain and bias conditions.
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.
;
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.