Browsing by Author "Chen, L. J."

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Effects of capping layers on the electrical characteristics of nickel silicided junctions
(2007-05-01)
Wu, Chi-Chang
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Wu, Wen-Fa
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Su, P. Y.
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Chen, L. J.
;
Ko, Fu-Hsiang
In this paper, effects of capping layers on formation and electrical properties of Ni-silicided junctions have been investigated. Nickel silicide films using the Ti or TiN-capped layer process are used to compare to those by the uncapped process. The uncapped (Ni single layer) and TiN-capped samples are shown to exhibit better thermal stability than the Ti-capped samples. For the silicided junctions, samples using Ti capping layer processes exhibit larger leakage current densities. A high-resistivity NiTiSi, compound layer is formed on the surface during silicidation for the Ti-capped sample, while the uncapped and TiN-capped samples are not. In addition, it is found that the thickness of NiSi layer, as well as the Ni,TiySi, layer, increases with increasing the Ti capping layer thickness. The formation of Ni,TiySi, layer not only increases the contact resistance, but also deepens the silicide thickness. (c) 2007 Elsevier B.V. All rights reserved.
Growth of Multiple Metal/Semiconductor Nanoheterostructures through Point and Line Contact Reactions
(2010-10-01)
Wu, W. W.
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Lu, K. C.
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Wang, C. W.
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Hsieh, H. Y.
;
Chen, S. Y.
Forming functional circuit components in future nanotechnology requires systematic studies of solid-state chemical reactions in the nanoscale Here, we report efficient and unique methods, point and line contact reactions on Si nanowtres, fabricating high quality and quantity of multiple nanoheterostructures of NiSi/Si and investigation of NiSi formation in nanoscale By using the point contact reaction between several Ni nanodots and a Si nanowire carried out in situ in an ultrahigh vacuum transmission electron microscopy, multiple sections of single-crystal NISI and Si with very sharp interfaces were produced in a Si nanowire Owing to the supply limited point contact reaction, we propose that the nucleation and growth of the sugar cane-type NISI grains start at the middle of the point contacts between two Ni nanodots and a Si nanowire The reaction happens by the dissolution of Ni into the Si nanowire at the point contacts and by interstitial diffusion of Ni acorns within a Si nanowire. The growth of NISI stops as the amount of Ni in the Ni nanodots is consumed Additionally, without lithography, utilizing the line contact reaction between PS nanosphere-mediated Ni nanopatterns and a nanowire of Si. we have fabricated periodic multi-NiSi/Si/NiSi heterostructure nanonowires that may enhance the development of circuit elements in nanoscale electronic devices Unlike the point contact reaction, suicide growth starts at the contact area in the line contact reaction, the different silicide formation modes resulting from point and line contact reactions are compared and analyzed A mechanism on the basis of flux divergence is proposed for controlling the growth of the nanomultiheterostructures
Growth of Multiple Metal/Semiconductor Nanoheterostructures through Point and Line Contact Reactions
(2010-10-01)
Wu, W. W.
;
Lu, K. C.
;
Wang, C. W.
;
Hsieh, H. Y.
;
Chen, S. Y.
Forming functional circuit components in future nanotechnology requires systematic studies of solid-state chemical reactions in the nanoscale Here, we report efficient and unique methods, point and line contact reactions on Si nanowtres, fabricating high quality and quantity of multiple nanoheterostructures of NiSi/Si and investigation of NiSi formation in nanoscale By using the point contact reaction between several Ni nanodots and a Si nanowire carried out in situ in an ultrahigh vacuum transmission electron microscopy, multiple sections of single-crystal NISI and Si with very sharp interfaces were produced in a Si nanowire Owing to the supply limited point contact reaction, we propose that the nucleation and growth of the sugar cane-type NISI grains start at the middle of the point contacts between two Ni nanodots and a Si nanowire The reaction happens by the dissolution of Ni into the Si nanowire at the point contacts and by interstitial diffusion of Ni acorns within a Si nanowire. The growth of NISI stops as the amount of Ni in the Ni nanodots is consumed Additionally, without lithography, utilizing the line contact reaction between PS nanosphere-mediated Ni nanopatterns and a nanowire of Si. we have fabricated periodic multi-NiSi/Si/NiSi heterostructure nanonowires that may enhance the development of circuit elements in nanoscale electronic devices Unlike the point contact reaction, suicide growth starts at the contact area in the line contact reaction, the different silicide formation modes resulting from point and line contact reactions are compared and analyzed A mechanism on the basis of flux divergence is proposed for controlling the growth of the nanomultiheterostructures
In situ TEM investigation of dynamical changes of nanostructures
(2010-11-22)
Chen, L. J.
;
Wu, W. W.
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材料科學與工程學系
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Department of Materials Science and Engineering
In situ investigation of the temperature induced phase transformation, structural and chemical evolution of nanocrystals is important for understanding the structure and stability of nanomaterials. Transmission electron microscopy (TEM), one of the most powerful tools for characterizing nanostructured materials, is essential for the development of nanotechnology. In situ TEM is a technique that allows a direct observation of dynamic properties in nanoscale. Recent development of ultra-high vacuum TEM (UHV-TEM) further enables the investigation on atomic-scale materials systems in a clean environment. The appropriate utilization of the UHV-TEM will be beneficial in studying the fundamental mechanisms of dynamic reactions, formation of transient phase, solid-state amorphization, epitaxial growth, growth kinetics and evolution of defects. In this paper, we present the most recent progress in observing dynamic processes in nanoscale by in situ UHV-TEM. (C) 2010 Elsevier B.V. All rights reserved.
In situ TEM investigation of dynamical changes of nanostructures
(2010-11-22)
Chen, L. J.
;
Wu, W. W.
;
材料科學與工程學系
;
Department of Materials Science and Engineering
In situ investigation of the temperature induced phase transformation, structural and chemical evolution of nanocrystals is important for understanding the structure and stability of nanomaterials. Transmission electron microscopy (TEM), one of the most powerful tools for characterizing nanostructured materials, is essential for the development of nanotechnology. In situ TEM is a technique that allows a direct observation of dynamic properties in nanoscale. Recent development of ultra-high vacuum TEM (UHV-TEM) further enables the investigation on atomic-scale materials systems in a clean environment. The appropriate utilization of the UHV-TEM will be beneficial in studying the fundamental mechanisms of dynamic reactions, formation of transient phase, solid-state amorphization, epitaxial growth, growth kinetics and evolution of defects. In this paper, we present the most recent progress in observing dynamic processes in nanoscale by in situ UHV-TEM. (C) 2010 Elsevier B.V. All rights reserved.
In Situ Ultrahigh Vacuum Transmission Electron Microscope Investigations of Nanostructures
(2009-07-01)
Chen, L. J.
;
Wu, W. W.
;
材料科學與工程學系
;
Department of Materials Science and Engineering
In-situ TEM Study of Electromigration in Cu lines
(2009)
Liao, C. N.
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Chen, K. C.
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Wu, W. W.
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Chen, L. J.
;
Tu, K. N.
The density of electric current passing through interconnecting wires in integrated circuits (IC) is increasing with continuous miniaturization of IC. Under a high operating temperature and large electric current density, some voids and hillocks may form in the interconnecting wires due to electromigration (EM), leading to device failures eventually. In this study atomic-scale EM in unpassivated copper lines has been investigated in ultrahigh vacuum by in situ transmission electron microscopy (TEM). The EM-induced atomic surface diffusion was found to be crystal-orientation dependent and occurred preferentially on the {111} planes along < 110 > directions. The high-resolution TEM images and the electron diffraction patterns of a (111)-oriented Cu grain in the Cu line revealed an EM-induced step structure at surface. Moreover, the triple point where a twin boundary meets a grain boundary was found to slow down atomic EM at grain boundaries because of the incubation time of nucleation of a new step at the triple point. The long incubation time slows down the overall rate of atomic transport. The results suggest that the EM reliability of Cu interconnects may be enhanced by forming a high density of nanometer scaled twins in the coarse-grain Cu wires.
In-situ Ultrahigh Vacuum Transmission Electron Microscope Investigations of Nanostructures
(2010)
Chen, L. J.
;
Wu, W. W.
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Low-dimensional nanostructures, such as nanodots, nanowires and nanotubes, are especially attractive candidates for developing a bottom-up paradigm for nanotechnology-enabled architectures. In situ ultrahigh vacuum transmission electron microscope (UHV-TEM) is a powerful tool to investigate the dynamic changes of nanostructures. By observing growth and phase transitions in situ, understanding of their mechanisms can be used to model relevant processes. Recent development of UHV-TEM further enables the investigation on atomic-scale materials systems in a clean environment. With the precise knowledge of the changes occurred on an atomic level, accurate control of the growth process can be achieved [1]. The appropriate utilization of the UHV-TEM will be beneficial in studying the fundamental mechanisms of dynamic reactions, formation of transient phase, solid-state amorphization, epitaxial growth, growth kinetics and evolution of defects. The dynamical changes occurred on the nano scale are often unexpected, which also underscores the importance of the approach. In this presentation, we will highlight several examples to demonstrate the unique capability of in situ TEM to study the dynamical changes. The examples include growth of high-density titanium silicide nanowires in a single direction on a silicon surface [2], controlled growth of atomic-scale Si layer with huge strain in the nano-heterostructure NiSi/Si/NiSi through point contact reaction between nano-wires of Si and Ni and reactive epitaxial growth [3], observation of repeating events of nucleation in epitaxial growth of nano CoSi2 in nanowires of Si [4] and observations of electromigration in copper lines at room temperature [5].
Metal nanocrystals as charge storage nodes for nonvolatile memory devices
(2007-02-10)
Yeh, P. H.
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Chen, L. J.
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Liu, P. T.
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Wang, D. Y.
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Chang, T. C.
The memory effects of the metal nanocrystals were found to be more pronounced than those of the semiconductor nanocrystals. Various metal nanocrystals as charge storage nodes are reviewed. The memory effects have strong relationship with the work function, and the work function can be modulated by changing the metal species. By tunneling dielectrics engineering, the optimum I-GWrite/Erase/I-G Retention ratio can be obtained. (c) 2006 Elsevier Ltd. All rights reserved.
Synthesis of ethanol-soluble few-layer graphene nanosheets for flexible and transparent conducting composite films
(2011-07-22)
Nguyen, D. D.
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Tai, N. H.
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Chueh, Y. L.
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Chen, S. Y.
;
Chen, Y. J.
We report a facile method of preparing few-layer graphene nanosheets (FLGs), which can be soluble in ethanol. Atomic force microscopy and high-resolution transmission electron microscopy studies reveal that FLGs have average thicknesses in the range of 2.6-2.8 nm, corresponding to 8-9 layers. A graphene/nafion composite film has a sheet resistance of 9.70 k Omega/sq at the transmittance of 74.5% (at 550 nm) while the nafion film on polyethylene terephthalate has a sheet resistance of 128 k Omega/sq at transmittance of 90.0%. For the cycling/bending test, almost no change in resistance was exhibited when the film was bent at an angle up to 140 degrees, and no obvious deviation in resistance could be found after 100 bending cycles was applied. In addition, an FLGs-poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) composite layer was demonstrated as the effective hole transporting layer to improve the hole transporting ability in an organic photovoltaic device, with which the power conversion efficiency was enhanced from 3.10% to 3.70%. The results demonstrated the promising applications of FLGs on graphene-based electronics, such as transparent electrode and flexible conducting film.