Browsing by Author "Huang, T. C."

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A novel technique to fabricate 28 nm p-MOSFETs possessing gate oxide integrity on an embedded SiGe channel without silicon surface passivation
(2012-12-12)
Yu, M. H.
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Liao, M. H.
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Huang, T. C.
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Wang, L. T.
;
Lee, T. L.
A novel technique to create a suspending stacked gate oxide and subsequently to fill in an embedded SiGe channel (ESC) between the gate oxide and the underlying silicon substrate is proposed for the first time to fabricate 28 nm p-metal-oxide-semiconductor field-effect transistors (p-MOSFET). Without Si surface passivation on the ESC, such an ESC structure could achieve a p-FET transconductance (G(m)) gain of 26% higher and a better I-on-I-off performance gain of 8% than that of conventional strained Si p-FETs with the source/drain (S/D) SiGe. Better S/D resistance (R-sd) in the resistance versus gate length plot and improved swing slope of the I-d-V-gs plot indicates higher mobility in the ESC devices. Moreover, the off-state gate current of the ESC structure is also comparable to the conventional ones. From the x-ray photoelectron spectrum analysis, only the Si-O bonding, and no Ge-O bonding at the SiGe/SiO2 interface could account for this superior gate oxide integrity for the ESC and strained Si structure. Therefore, such a novel technique with an ESC structure is very promising for the 28 nm p-MOSFET devices era.
Anisotropic Ultrafast Dynamics of Quasiparticles on CuO(2) Planes of Y(0.7)Ca(0.3)Ba(2)Cu(3)O(7-delta)
(2010-07-01)
Luo, C. W.
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Huang, T. C.
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Chiang, M. T.
;
Wu, K. H.
;
Juang, J. Y.
The orientation-resolved femtosecond spectroscopy, combined with the well-textured (110)- and (001)Y(0.7)Ca(0.3)Ba(2)Cu(3)O(7-delta) thin films, serves as an effective probe to quasiparticle relaxation dynamics on the ab planes and along the diagonal orientations. The significant divergences in the temperature-dependent relaxation time (tau) associated with the opening of superconducting gap were observed along the nodal directions and on the CuO(2) planes which are dominated by the a axis and b axis in the over-doped region. Moreover, the divergence in the temperature-dependent served along the nodal direction disappears around optimal doped region. This implies that the superconducting gap evolves from the dominant s-wave symmetry in over-doped region into the dominant d-wave symmetry in optimal doped region.
Anisotropic Ultrafast Dynamics of Quasiparticles on CuO2 Planes of Y0.7Ca0.3Ba2Cu3O7-delta
(2010-07-01)
Luo, C. W.
;
Huang, T. C.
;
Chiang, M. T.
;
Wu, K. H.
;
Juang, J. Y.
The orientation-resolved femtosecond spectroscopy, combined with the well-textured (110)- and (001)Y0.7Ca0.3Ba2Cu3O7-delta thin films, serves as an effective probe to quasiparticle relaxation dynamics on the ab planes and along the diagonal orientations. The significant divergences in the temperature-dependent relaxation time (tau) associated with the opening of superconducting gap were observed along the nodal directions and on the CuO2 planes which are dominated by the a axis and b axis in the over-doped region. Moreover, the divergence in the temperature-dependent served along the nodal direction disappears around optimal doped region. This implies that the superconducting gap evolves from the dominant s-wave symmetry in over-doped region into the dominant d-wave symmetry in optimal doped region.
Electron-Boson Coupling Constant of Oxygen-Deficient Y(0.7)Ca(0.3)Ba(2)Cu(3)O(7-delta) Measured by Ultrafast Spectroscopy
(2011-01-01)
Luo, C. W.
;
Chen, J. -Y.
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Huang, T. C.
;
Wu, K. H.
;
Lin, J. -Y.
The ultrafast dynamics in an (001) oxygen-deficient Y(0.7)Ca(0.3)Ba(2)Cu(3)O(7-delta) thin film were measured by using the ultrafast spectroscopy. According to the model of time-dependent distributions of electrons in the case of electron-phonon relaxation, the electron-boson coupling constant lambda could be directly obtained from the relaxation time of the transient reflectivity change (Delta R/R). For the overdoped case with T (c)=61.3 K and the underdoped case with T (c)=65.5 K, the relaxation time of Delta R/R is around 4.32 ps and 3.66 ps, respectively, which correspond to lambda similar to 0.06. However, the lambda become larger (similar to 0.15) in the optimal doped region with T (c)=82.1 K while the relaxation time of Delta R/R shrinks to similar to 1.51 ps. These results indicate that the lambda is strongly hole-doping dependent, which may govern the T (c) of cuprate superconductors.
Electron-Boson Coupling Constant of Oxygen-Deficient Y0.7Ca0.3Ba2Cu3O7-delta Measured by Ultrafast Spectroscopy
(2011-01-01)
Luo, C. W.
;
Chen, J. -Y.
;
Huang, T. C.
;
Wu, K. H.
;
Lin, J. -Y.
The ultrafast dynamics in an (001) oxygen-deficient Y0.7Ca0.3Ba2Cu3O7-delta thin film were measured by using the ultrafast spectroscopy. According to the model of time-dependent distributions of electrons in the case of electron-phonon relaxation, the electron-boson coupling constant lambda could be directly obtained from the relaxation time of the transient reflectivity change (Delta R/R). For the overdoped case with T (c)=61.3 K and the underdoped case with T (c)=65.5 K, the relaxation time of Delta R/R is around 4.32 ps and 3.66 ps, respectively, which correspond to lambda similar to 0.06. However, the lambda become larger (similar to 0.15) in the optimal doped region with T (c)=82.1 K while the relaxation time of Delta R/R shrinks to similar to 1.51 ps. These results indicate that the lambda is strongly hole-doping dependent, which may govern the T (c) of cuprate superconductors.
Electronic structure investigation of a charge density wave coupled to a metal-to-metal transition in Ce3Co4Sn13
(2018-12-18)
Singh, A.
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Huang, H. Y.
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Chin, Y. Y.
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Liao, Y. F.
;
Huang, T. C.
We study the electronic structure of the skutterudite Ce3Co4Sn13, which is known to exhibit a charge density wave (CDW) transition, at temperature T-CDW similar to 160 K, coupled to a metal-to-metal transition. We use temperature dependent hard x-ray photoemission spectroscopy (HAXPES) and x-ray absorption spectroscopy (XAS) to investigate the occupied and unoccupied electronic states of Ce3Co4Sn13. The Co 2p and Sn 3p core level spectra show small but finite shifts in binding energy positions across T-CDW while Ce 3d core level spectra do not show any change across the transition. The Ce M-4,M-5-edge XAS spectrum compared with calculations indicate a typical trivalent ionic Ce3+ spectral shape, ruling out Kondo screening in Ce3Co4Sn13. In contrast, the Co L-2,L-3-edge XAS spectrum compared with a calculated spectrum shows evidence for hybridization with neighboring Sn atoms in a trigonal prismatic co-ordination. Temperature dependent XAS across the Co L-2,L-3-edge shows a small shift across T-CDW, consistent with HAXPES results. Detailed XAS measurements as a function of temperature show that the spectral shifts occur with a hysteresis across T-CDW , indicative of a first-order transition. Valence band spectra show a normal Fermi edge above and below T-CDW. The Co 3d states are observed at a binding energy of similar to 2 eV while the Ce 4f states occur as a weak feature within 0.5 eV of the Fermi level. The results suggest an unusual CDW transition coupled to a metal-to-metal transition in Ce3Co4Sn13.
The Strained-SiGe Relaxation Induced Underlying Si Defects Following the Millisecond Annealing for the 32 nm PMOSFETs
(2012)
Yu, M. H.
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Wang, L. T.
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Huang, T. C.
;
Lee, T. L.
;
Cheng, H. C.
The formation of the induced defects in the underlying Si substrate from the interaction of the partly relaxed source/drain strained-SiGe layer and subsequent millisecond annealing (MSA) have been systematically explored. It could be found that implantation in the shallower region of the strained-SiGe layer did not form defects in the underlying Si because the remaining strained-SiGe layer was sufficiently thick to resist wafer bending in response to the MSA thermal stress. However, deeper medium-level implantation indeed destroyed the part of the pseudomorphic strained-SiGe and the remaining strained-SiGe was too thin to withstand a significantly compressive stress induced by MSA surface heating and larger coefficient of thermal expansion (CTE) for SiGe than it for Si. Then brittle silicon substrate suffered a great tensile stress to generate numerous defects into plastic deformation. During MSA cooling, the over-bending of the surface SiGe layer contracted more than Si substrate and further results in highly tensile bending. Consequently, high defect density in the underlying Si results in high junction leakage and wafer bending leads to photolithographic limitation. A new approach for modifying the implantation conditions was developed to achieve a relaxation-less strained-SiGe layer and defect-free underlying Si substrate for the 32 nm PMOSFETs. (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.017203jes] All rights reserved.
Ultrafast dynamics in oxygen-deficient Y(0.7)Ca(0.3)Ba(2)Cu(3)O(7-delta) superconductors
(2009)
Luo, C. W.
;
Huang, T. C.
;
Wu, K. H.
;
Juang, J. Y.
;
Lin, J-Y
The transient reflectivity change (Delta R/R) in oxygen-deficient Y(0.7)Ca(0.3)Ba(2)Cu(3)O(7-delta) (YCaBCO) thin films have been systematically measured at various temperatures by femtosecond spectroscopy. The magnitude change of Delta R/R from normal state to superconducting state were clearly observed in YCaBCO with various oxygen deficient, e.g. from overdoped region over optimaldoped region to underdoped region. Additionally, the carrier-phonon coupling strength was also characterized by the relaxation time of Delta R/R at various temperatures and hole concentration.