Browsing by Author "Chi, C. C."

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A wide range THz pulses generation in ZnTe crystals
(2012)
Ku, S. A.
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Tu, C. -M.
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Luo, C. W.
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Wu, K. H.
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Yabushita, A.
The THz generation in ZnTe crystals by widely varying pumping fluences is reported. Some abnormal nonlinear effects were observed including the evolution of THz spectra and the phase shift of temporal waveforms. Moreover, the THz efficiency can enhance again at high pumping fluence due to the saturation of free carrier.
Advanced Metal-Gate/High-kappa CMOS with Small EOT and Better High Field Mobility
(2012)
Chin, Albert
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Chen, W. B.
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Chen, P. C.
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Wu, Y. H.
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Chi, C. C.
Continuously down-scaling the operation voltage, saving energy, and maintaining high performance are the major challenge for CMOS device. Small 0.95 similar to 1.4 nm equivalent-oxide thickness (EOT) and 1.4 similar to 2.5X better mobility than universal SiO2/Si data are achieved in metal-gate/high-kappa/Ge CMOS at 1 MV/cm effective field (E-eff). These excellent performances were achieved by using interface engineering and novel process, to overcome the poor high-kappa/Ge interface reaction, low source-drain dopant activation, and n(+)/p ohmic contact. The all-Ge CMOS with measured higher electron and hole mobility has irreplaceable merits of much simpler process, lower cost, and potentially higher yield than the InGaAs-nMOS/Ge-pMOS platform for IC manufacture.
Comparison of InGaAs MOSFETs with germanium-on-insulator CMOS
(2006-08-01)
Chin, Albert
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Chen, C.
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Yu, D. S.
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Kao, H. L.
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McAlister, S. P.
High mobility channel materials such as Ge and compound semiconductors (CS) show promise for future generation MOSFETs. The challenge is to integrate these materials with a Si substrate and create good interfaces in the devices. Here we show dislocation-free CSOI and Ge-on-insulator (GOI) devices with good characteristics. The InAlAs/InGaAs/InAlAs-OI on Si MESFETs shows a mobility of 8100 cm(2)/V s. To reduce the leakage current an Al2O3/InGaAs MOSFET was fabricated. Good 451 cm(2)/V S mobility was obtained, higher than the 340 cm(2)/V S of GOI MOSFETs. However the marginally better mobility than GOI and 18X lower mobility than MESFETs indicate that the soft phonon scattering, high-kappa interface scattering and process variations are challenges for CS MOSFETs. In contrast, the GOI CMOS provides a simpler process and significantly higher electron and hole mobilities than its Si counterparts. (C) 2006 Elsevier Ltd. All rights reserved.
Critical current of superconducting YBa2Cu3O7-delta films with different in-plane orientations
(2007-06-01)
Lin, P. A.
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Chi, C. C.
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Rosenstein, B.
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電子物理學系
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Department of Electrophysics
By using a pulsed-laser deposition (PLD) technique, we grow high quality YBa2Cu3O7-delta films on YSZ (Yt-stabilized Zr) substrates with 0-degree and 45-degree in-plane orientations at 810 degrees C and 690 degrees C respectively. Surprisingly, despite the large difference in growth temperature the qualities of the films are almost the same. To study the subtle differences between these two types of films, we measured both the temperature and magnetic field dependencies of the critical current. Although there is very little difference in their magnetic field dependence, there is a distinct temperature dependence, i.e. J(c)(1 - T/T-c) proportional to (1 - T/T-c)(5/4) for 0 degree in-plane orientation and proportional to (1 - T/T-c)(3/2) for 45 degree in-plane orientation at temperatures near T-c. We also studied the critical current densities with different fractions of mixed orientations, and found an empirical formula J(c) proportional to e(5 alpha) where alpha is the fraction of the majority domain.
DC-RF performance improvement for strained 0.13 mu m MOSFETs mounted on a flexible plastic substrate
(2006)
Kao, H. L.
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Chin, Albert
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Liao, C. C.
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Tseng, Y. Y.
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McAlister, S. P.
By applying 0.7% tensile strain to the flexible die of a 0.13 mu m thin-body (40 mu m) Si MOSFET mounted on plastic, both the DC and RF performance have been improved. The current I(d,sat) was 14.3% higher, and f(T) increased from 103 to 118 GHz with NF(min) decreasing from 0.89 to 0.75 dB at 10 GHz. These improvements are comparable with those for SiN-capped 90 nm strained-Si nMOS and consistent with device simulations. The approach has the advantages of better RF passive devices on the insulating plastic substrate and low cost.
Ferromagnetic GeMn thin film prepared by ion implantation and ion beam induced epitaxial crystallization annealing
(2012-06-11)
Chen, C. H.
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Niu, H.
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Yan, D. C.
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Hsieh, H. H.
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Lee, C. P.
Ferromagnetic GeMn was prepared by Mn implantation followed by ion beam-induced epitaxial crystallization annealing. The damage caused by Mn implantation was repaired by subsequent helium ion irradiation. Various structural analyses were performed and Mn ions were found to incorporate uniformly into the Ge lattice without the formation of any secondary phases. The remnant magnetic moment exhibited room temperature ferromagnetism. Anomalous Hall effect and field dependent magnetization were measured at the same time at room temperature indicating spin polarized free carrier transport. Additional measurement using x-ray magnetic circular dichroism also revealed that the carriers were spin-polarized. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4729752]
Higher kappa Metal-Gate/High-kappa/Ge n-MOSFETs with < 1 nm EOT Using Laser Annealing
(2010)
Chen, W. B.
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Shie, B. S.
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Chin, Albert
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Hsu, K. C.
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Chi, C. C.
High performance metal-gate/high-kappa/Ge n-MOSFETs are reached with low 73 Omega/sq sheet resistance (R(s)), 1.10 ideality factor, 0.95 nm EOT, small 106 mV/dec sub-threshold slope (SS), good 285 cm(2)/Vs high-field (1 MV/cm) mobility and low 37 mV Delta V(t) PBTI (85 degrees C, 1 hr). This is achieved by using 30-ns laser annealing that leads to 57% higher gate capacitance, better n(+)/p junction and 10X better I(ON)/I(OFF).
Improved Capacitance Density and Reliability of High-k Ni/ZrO(2)/TiN MIM Capacitors Using Laser-Annealing Technique
(2010-07-01)
Tsai, C. Y.
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Chiang, K. C.
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Lin, S. H.
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Hsu, K. C.
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Chi, C. C.
We have fabricated high-k Ni/ZrO(2)/TiN metal-insulator-metal capacitors with a very high 52-fF/mu m(2) capacitance density, a low leakage current of 1.6 x 10(-7) A/cm(2), and good ten-year reliability with a small Delta C/C of 1.7% at 2 V. From X-ray diffraction measurements, laser annealing can improve the permittivity of ZrO(2) due to tetragonal-phase formation which in turn helps enhance capacitance density and reliability. Such excellent device integrity is attributed to the combination of enhanced ZrO(2) tetragonal phase by laser annealing, high work-function Ni electrode, and good bottom-interface treatment.
Improved Capacitance Density and Reliability of High-k Ni/ZrO2/TiN MIM Capacitors Using Laser-Annealing Technique
(2010-07-01)
Tsai, C. Y.
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Chiang, K. C.
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Lin, S. H.
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Hsu, K. C.
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Chi, C. C.
We have fabricated high-k Ni/ZrO2/TiN metal-insulator-metal capacitors with a very high 52-fF/mu m(2) capacitance density, a low leakage current of 1.6 x 10(-7) A/cm(2), and good ten-year reliability with a small Delta C/C of 1.7% at 2 V. From X-ray diffraction measurements, laser annealing can improve the permittivity of ZrO2 due to tetragonal-phase formation which in turn helps enhance capacitance density and reliability. Such excellent device integrity is attributed to the combination of enhanced ZrO2 tetragonal phase by laser annealing, high work-function Ni electrode, and good bottom-interface treatment.
Local structure and magnetic properties of ferromagnetic GaMnAs made by helium ion induced epitaxial crystallization annealing
(2014-08-15)
Chen, C. H.
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Niu, H.
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Yan, D. C.
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Hsieh, H. H.
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Huang, R. T.
In this study we show GaMnAs preparation by Mn implantation in GaAs followed by helium ion beam induced epitaxial crystallization annealing. The characteristics of the Mn-implanted layer were investigated by X-ray diffraction, and transmission electron microscopy. The magnetic nature of the Mn-implanted layer was investigated with a superconducting quantum interference device. Structure analysis showed that Mn ions were incorporated substitutionally into the GaAs lattice without the formation of any detectable secondary phases. The remanent magnetic moment exhibited room temperature ferromagnetism. Additional measurement using X-ray magnetic circular dichroism also revealed that the carriers were spin polarized. (C) 2014 Elsevier B.V. All rights reserved.
Local structure and magnetic properties of ferromagnetic GaMnAs made by helium ion induced epitaxial crystallization annealing
(2014-08-15)
Chen, C. H.
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Niu, H.
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Yan, D. C.
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Hsieh, H. H.
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Huang, R. T.
In this study we show GaMnAs preparation by Mn implantation in GaAs followed by helium ion beam induced epitaxial crystallization annealing. The characteristics of the Mn-implanted layer were investigated by X-ray diffraction, and transmission electron microscopy. The magnetic nature of the Mn-implanted layer was investigated with a superconducting quantum interference device. Structure analysis showed that Mn ions were incorporated substitutionally into the GaAs lattice without the formation of any detectable secondary phases. The remanent magnetic moment exhibited room temperature ferromagnetism. Additional measurement using X-ray magnetic circular dichroism also revealed that the carriers were spin polarized. (C) 2014 Elsevier B.V. All rights reserved.
Pulsed terahertz radiation due to coherent phonon-polariton excitation in < 110 > ZnTe crystal
(2012-11-01)
Tu, C. M.
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Ku, S. A.
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Chu, W. C.
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Luo, C. W.
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Chen, J. C.
Pulsed terahertz (THz) radiation, generated through optical rectification (OR) by exciting < 110 > ZnTe crystal with ultrafast optical pulses, typically consists of only a few-cycles of electromagnetic field oscillations with a duration about a couple of picoseconds. However, it is possible, under appropriate conditions, to generate a long damped oscillation tail (LDOT) following the main cycles. The LDOT can last tens of picoseconds and its Fourier transform shows a higher and narrower frequency peak than that of the main pulse. We have demonstrated that the generation of the LDOT depends on both the duration of the optical pulse and its central wavelength. Furthermore, we have also performed theoretical calculations based upon the OR effect coupled with the phonon-polariton mode of ZnTe and obtained theoretical THz waveforms in good agreement with our experimental observation. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4764917]
Saturation of the free carrier absorption in ZnTe crystals
(2013-06-17)
Ku, S. A.
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Tu, C. M.
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Chu, W. -C.
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Luo, C. W.
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Wu, K. H.
This study systematically investigates the influence of free carriers on the generation of THz in ZnTe crystals, over a wide range of pumping fluences. As the pumping fluence is increased (< 6.36 mJ/cm(2)), the concentration of free carriers gradually increases and the THz output power is saturated, as clearly demonstrated by the time delay in the THz temporal waveforms, the changes in the THz spectral weight and the red-shift in the PL spectra. For high pumping fluences (> 6.36 mJ/cm(2)), spectacularly, there is a significant quadratic increase in the THz output power when the pumping fluence is increased, as well as at low pumping fluences of < 0.58 mJ/cm(2), because of the saturation of free carriers. (C) 2013 Optical Society of America
Strain enhanced DC-RF performance of 0.13 mu m nMOSFETs on flexible plastic substrate
(2006-07-06)
Chin, A.
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Kao, H. L.
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Kao, C. H.
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Liao, C. C.
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Tseng, Y. Y.
A 14.3% saturation current I-d,(sat) improvement and 0.75 dB minimum noise figure (NFmin) at 10 GHz were measured by applying similar to 0.7% tensile strain for 16 finger, 0.13 mu m RF MOSFETs with thin-body (40 mu m) substrate mounted on plastic. These excellent results for mechanical-strain on DC-RF MOSFETs are better than those of SiN-capped 90 nm strained-Si nMOSFETs and consistent with device simulations.