Browsing by Author "Tsai, C. Y."

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Anisotropic strain, magnetic properties, and lattice dynamics in self-assembled multiferroic CoFe2O4-PbTiO3 nanostructures
(2014-04-07)
Tsai, C. Y.
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Chen, H. R.
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Chang, F. C.
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Kuo, H. H.
;
Cheng, H. M.
We investigate the anisotropic stress dependent magnetic and phonon behaviors in self-assembled CoFe2O4-PbTiO3 (CFO-PTO) nanostructures deposited on SrRuO3 buffered SrTiO3 substrates of various thickness. The increased vertical compressed stress with increasing thickness enhances the vertical magnetic anisotropy of CFO while gradually reducing the vertical polarization of PTO. By applying the magnetic-field dependent Raman scattering, the CFO-A(1g) and T-2g(1) phonon frequencies shift oppositely because of the magnetostriction. Moreover, the PTO-A(1) mode intensities anomalously enhance and the A(1) and E mode frequencies, respectively, increase and decrease, which prove the existence of the stress-mediated magnetoelectric (ME) effect. This study shows that the ME transmission process is dominated by interfacial stress, which is critical for enhancing the ME efficiency. (C) 2014 AIP Publishing LLC.
Arsenic-Implanted HfON Charge-Trapping Flash Memory With Large Memory Window and Good Retention
(2011-03-01)
Tsai, C. Y.
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Lee, T. H.
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Chin, Albert
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電機工程學系
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Department of Electrical and Computer Engineering
We have fabricated the TaN-[SiO(2)-LaAlO(3)]-HfON-[LaAlO(3)-SiO(2)]-Si charge-trapping Flash device. A large 6.4-V initial memory window, a 4.3-V 10-year extrapolated retention window at 125 degrees C, and a 5.5-V endurance window at 10(6) cycles were measured under very fast 100-mu s and low +/- 16-V program/erase. These excellent results were achieved using an As(+) implant into the HfON trapping layer, which were significantly better than those of the control device without ion implantation.
Corrosion behaviors of austenitic Fe-30Mn-7Al-xCr-1C alloys in 3.5% NaCl solution
(2009-04-15)
Tuan, Y. H.
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Wang, C. S.
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Tsai, C. Y.
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Chao, C. G.
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Liu, T. F.
The corrosion behaviors of the as-quenched Fe-30wt.%Mn-7wt.%Al-xwt.%Cr-1 wt.%C alloys (x = 0, 3, 6 and 9) in 3.5% NaCl have been investigated. Passivation could be observed for all the alloys except for the alloy without Cr content. The corrosion potential (E(corr)) and pitting potential (E(pp)) increased pronouncedly with increasing Cr content up to 6 wt.%, and decreased as Cr content up to 9 wt.%. The decrease of E(corr) and E(pp) of the alloy containing 9 wt.% Cr was due to the formation of (Fe,Mn,Cr)(7)C(3) carbides in the austenite matrix and on the grain boundaries. It is noted that the corrosion behaviors of the austenitic Fe-Mn-Al-Cr-C alloys with higher Cr(>= 3 wt.%) content have never been reported in previous literatures. (C) 2008 Elsevier B.V. All rights reserved.
Development of new features of ant colony optimization for flowshop scheduling
(2008-04-01)
Lin, B. M. T.
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Lu, C. Y.
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Shyu, S. J.
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Tsai, C. Y.
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資訊管理與財務金融系註：原資管所+財金所
Ant colony optimization (ACO) is a meta-heuristic based on the indirect communication of a colony of artificial ants mediated by pheromone trails with the collaboration and knowledge-sharing mechanism during their food-seeking process. In this study, we introduce two new features that are inspired from real ant behavior to develop a new ACO algorithm to produce better solutions. The proposed ACO algorithm is applied to two NP-hard flowshop scheduling problems. The first problem is to minimize the total completion time and the second is to minimize a combination of makespan and total completion time. Numerical results indicate that the proposed new features of ACO are very effective and the synergy of combining all the new features for the proposed ACO algorithm can solve the two problems to a certain scale by producing schedules of better quality. (C) 2007 Elsevier B.V. All rights reserved.
Effect of geometry on the magnetic properties of CoFe2O4-PbTiO3 multiferroic composites
(2013)
Wang, B. Y.
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Wang, H. T.
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Singh, Shashi B.
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Shao, Y. C.
;
Wang, Y. F.
In this study, X-ray absorption near-edge structure (XANES), extended X-ray absorption fine structure (EXAFS), X-ray magnetic circular dichroism (XMCD) and element-and site-specific magnetic hysteresis (ESMH) are used to elucidate the effect of geometry (0-3- and 2-2-type) on the magnetic properties of CoFe2O4-PbTiO3 (CFO-PTO) multiferroic composites by comparison with those of the reference CFO and PTO powders. Magnetic Co ions in CFO have been confirmed to be located at both the tetrahedral (A)- and octahedral (B)-sites. CFO retains its mixed-spinel structure as verified by the EXAFS, XMCD and ESMH measurements. ESMH measurements further demonstrate that the magnetic moments of Co2+ and Fe3+/Fe2+ cations at both the A-and B-sites in the composites are smaller than those of the CFO powder. The reduction of the magnetic moments in the 2-2-type composite was larger than that in the 0-3-type composite. The reduction of the magnetic moments in the composites was attributable to the formation of anti-phase boundaries owing to the compressive strain in CFO, which is the largest strain in the 2-2-type composite. Based on the Ti L-3,L-2-edge XMCD measurements of the CFO-PTO composites, no induced magnetic moment was observed at the Ti sites in the PTO matrix, excluding the possibility that the Ti ions in the PTO matrix affect the magnetic properties of these CFO-PTO composites.
High Performance Ultra-Low Energy RRAM with Good Retention and Endurance
(2010)
Cheng, C. H.
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Tsai, C. Y.
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Chin, Albert
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Yeh, F. S.
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電子工程學系及電子研究所
High performance novel RRAM of 0.3 mu W set power (0.1 mu A at 3 V), 0.6 nW reset power (-0.3 nA at -1.8 V), fast 20 ns switching time, ultra-low 6 fJ switching energy, large 7x10(2) resistance window for 10(4) sec retention at 125 degrees C, and 10(6) cycling endurance were measured simultaneously. This is the first time that the switching energy of new non-volatile memory is close to existing Flash Memory.
High-Performance Charge-Trapping Flash Memory Device With an Ultrathin 2.5-nm Equivalent-Si(3)N(4)-Thickness Trapping Layer
(2012-01-01)
Tsai, C. Y.
;
Chin, Albert
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電機工程學系
;
Department of Electrical and Computer Engineering
We made the MoN-[SiO(2)-LaAlO(3)]-[Ge-HfON]-[LaAlO(3)-SiO(2)]-Si charge-trapping (CT) Flash device with a record-thinnest 2.5-nm equivalent-Si(3)N(4)-thickness trapping layer, a large 4.4-V initial memory window, a 3.2-V ten-year extrapolated retention window at 125 degrees C, and a 3.6-V endurance window at 106 cycles, under very fast 100 mu s and low +/- 16-V program/erase pulses. These were achieved using Ge reaction with a HfON trapping layer for better CT and retention.
High-Performance Charge-Trapping Flash Memory Device With an Ultrathin 2.5-nm Equivalent-Si3N4-Thickness Trapping Layer
(2012-01-01)
Tsai, C. Y.
;
Chin, Albert
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
We made the MoN-[SiO2-LaAlO3]-[Ge-HfON]-[LaAlO3-SiO2]-Si charge-trapping (CT) Flash device with a record-thinnest 2.5-nm equivalent-Si3N4-thickness trapping layer, a large 4.4-V initial memory window, a 3.2-V ten-year extrapolated retention window at 125 degrees C, and a 3.6-V endurance window at 106 cycles, under very fast 100 mu s and low +/- 16-V program/erase pulses. These were achieved using Ge reaction with a HfON trapping layer for better CT and retention.
High-Performance GaN MOSFET With High-k LaAlO(3)/SiO(2) Gate Dielectric
(2012-01-01)
Tsai, C. Y.
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Wu, T. L.
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Chin, Albert
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電機工程學系
;
Department of Electrical and Computer Engineering
Using a high-k LaAlO(3)/SiO(2) gate dielectric, the recessed-gate GaN MOSFET has a low threshold voltage (V(t)) of 0.1 V, low on-resistance (R(on)) of 13.5 Omega . mm, high breakdown voltage of 385 V, high transconductance (g(m)) of 136 mS/mm, and record-best normalized drive current (mu C(ox)) of 172 mu A/V(2). Such excellent device integrity is due to the small capacitance equivalent thickness of 3.0 nm, using a high-k gate dielectric and recessed-gate etching.
High-Performance GaN MOSFET With High-k LaAlO3/SiO2 Gate Dielectric
(2012-01-01)
Tsai, C. Y.
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Wu, T. L.
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Chin, Albert
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Using a high-k LaAlO3/SiO2 gate dielectric, the recessed-gate GaN MOSFET has a low threshold voltage (V-t) of 0.1 V, low on-resistance (R-on) of 13.5 Omega . mm, high breakdown voltage of 385 V, high transconductance (g(m)) of 136 mS/mm, and record-best normalized drive current (mu C-ox) of 172 mu A/V-2. Such excellent device integrity is due to the small capacitance equivalent thickness of 3.0 nm, using a high-k gate dielectric and recessed-gate etching.
Highly scaled charge-trapping layer of ZrON nonvolatile memory device with good retention
(2010-11-22)
Tsai, C. Y.
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Lee, T. H.
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Cheng, C. H.
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Chin, Albert
;
Wang, Hong
We have fabricated the TaN-[SiO(2)-LaAlO(3)]-ZrON-[LaAlO(3)-SiO(2)]-Si charge-trapping flash device with highly scaled 3.6 nm equivalent-Si(3)N(4)-thickness. This device shows large 4.9 V initial memory window, and good retention of 3.4 V ten-year extrapolated retention window at 85 degrees C, under very fast 100 mu s and low +/- 16 V program/erase. These excellent results were achieved using deep traps formed in ZrON trapping layer by As(+) implantation that was significantly better than those of control device without ion implantation. (C) 2010 American Institute of Physics. [doi:10.1063/1.3522890]
Highly-Scaled 3.6-nm ENT Trapping Layer MONOS Device with Good Retention and Endurance
(2010)
Tsai, C. Y.
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Lee, T. H.
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Chin, Albert
;
Wang, Hong
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Cheng, C. H.
Novel MONOS CTF, with record thinnest 3.6 nm ENT trapping layer, has a large 3.1 V 10-year extrapolated retention window at 125 degrees C and excellent 10(6) endurance at a fast 100 mu s and +/- 16 V program/erase. This is achieved using an As(+)-implanted higher. trapping layer with deep 5.1 eV work-function of As. In contrast, the un-implanted device only has a small 10-year retention window of 1.9 V at 125 degrees C.
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.
;
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.
;
Chiang, K. C.
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Lin, S. H.
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Hsu, K. C.
;
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.
Improved Device Characteristics in Charge-Trapping-Engineered Flash Memory Using High-kappa Dielectrics
(2009)
Chin, Albert
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Lin, S. H.
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Tsai, C. Y.
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Yeh, F. S.
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電子工程學系及電子研究所
The much shallower trap energy in Si3N4 of [poly-Si]-SiO2-Si3N4-SiO2- Si (SONOS) charge-trapping flash (CTF) device than conventional poly-Si floating gate flash is the fundamental challenge for CTF device. We have pioneered the high-trapping layer CTF memory to increase the trapping energy, where the AlGaN has a large conduction band offset to barrier oxide layer close to conventional poly-Si floating gate. Further device performance improvement is achieved using the novel Charge-Trapping-Engineered Flash (CTEF) device with double barriers for carrier confinements and double shallow-/deep-trapping layers for charge storage. Excellent memory device integrities of large extrapolated 10-year retention of 3.8 V at 150 degrees C, 4 logic levels MLC operation, very fast 100 mu s write speed and good 100,000 cycling stress are measured at the same time. These excellent results may allow further down-scaling the flash memory for additional nodes.
Optical properties of one- and two-dimensional excitons in m-plane ZnO/MgZnO multiple quantum wells
(2016-03-09)
Chen, H. R.
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Tsai, C. Y.
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Huang, Y. C.
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Kuo, C. C.
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Hsu, H. C.
Five pairs of ZnO/Zn0.9Mg0.1O multiple quantum wells (MQWs) with fixed barrier thickness of 55 nm and three well widths of 4, 8 and 16 nm have been grown on m-plane sapphires by pulsed laser deposition. Due to 2D quantum confinement with decreasing well width, the emission of excitons bound to the basal-plane stacking faults, which are one-dimensionally confined in MQWs, encounters larger blue shift than that of the near-band edge excitons. Furthermore, remarkably reducing coupling of free excitons with A1 longitudinal optical phonons is closely correlated with increasing exciton binding energy but enhanced coupling of E-2-low phonons is a result of increasing interaction with the interface phonons with decreasing well width.
Size-Dependent Trapping Effect in Nano-Dot Non-Volatile Memory
(2011)
Tsai, C. Y.
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Cheng, C. H.
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Chang, T. Y.
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Chou, K. Y.
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Chin, Albert
We report a flash memory using deep traps nano-dot formed in ZrON charge trapping layers by As+ implantation to improve the device performance of MONOS CTF device. The TaN-[SiO2-LaAlO3]-[As+-implanted ZrON]-[LaAlO3-SiO2]-Si device shows a 6 nm ENT, a large initial memory window of 9.8 V, a 10-year extrapolated retention window of 3.6 V at 85 degrees C, and an endurance window of 5.1 V after 10(5) cycles under fast 100 mu s and low +/- 16 V program/erase. The performance of As+-implanted ZrON is significantly better than that of stacked Si3N4/Ir-dot/HfON device with poor thickness scaling due to excess Ir metal dot.
Spin and phonon anomalies in epitaxial self-assembled CoFe2O4-BaTiO3 multiferroic nanostructures
(2014-06-23)
Tsai, C. Y.
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Cheng, H. M.
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Chen, H. R.
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Huang, K. F.
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Tsai, L. N.
Temperature dependent magnetic and phonon anomalies in epitaxial self-assembled CoFe2O4 (CFO) rods embedded in BaTiO3 (BTO) matrix nanostructures were investigated. The temperature dependence of A(1)(2TO) phonon frequency of BTO indicates that the BTO matrix experiences structural transformations. The lattice strain produced during the structural transformations drives spin reorientation in CFO rods, resulting in anomalous changes of magnetization. Through correlating the phonon anomalies with the increase of in-plane spin ordering, we show the spin-phonon coupling induces the softening of A(1g) and A(1)(2TO) phonons. It suggests that spin strongly couples with lattice strain and phonons in this nanostructure. (C) 2014 AIP Publishing LLC.
Spin and phonon anomalies in epitaxial self-assembled CoFe2O4-BaTiO3 multiferroic nanostructures
(2014-06-23)
Tsai, C. Y.
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Cheng, H. M.
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Chen, H. R.
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Huang, K. F.
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Tsai, L. N.
Temperature dependent magnetic and phonon anomalies in epitaxial self-assembled CoFe2O4 (CFO) rods embedded in BaTiO3 (BTO) matrix nanostructures were investigated. The temperature dependence of A(1)(2TO) phonon frequency of BTO indicates that the BTO matrix experiences structural transformations. The lattice strain produced during the structural transformations drives spin reorientation in CFO rods, resulting in anomalous changes of magnetization. Through correlating the phonon anomalies with the increase of in-plane spin ordering, we show the spin-phonon coupling induces the softening of A(1g) and A(1)(2TO) phonons. It suggests that spin strongly couples with lattice strain and phonons in this nanostructure. (C) 2014 AIP Publishing LLC.
Stress-mediated magnetic anisotropy and magnetoelastic coupling in epitaxial multiferroic PbTiO3-CoFe2O4 nanostructures
(2013-04-01)
Tsai, C. Y.
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Chen, H. R.
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Chang, F. C.
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Tsai, W. C.
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Cheng, H. M.
This study reports a self-assembled multiferroic nanostructure, composed of PbTiO3 (PTO) pillars embedded in a CoFe2O4 (CFO) matrix, deposited on MgO(001) by pulsed laser deposition. The epitaxial relationship in the PTO-CFO nanostructure is (100) [101](PTO) parallel to (001) [101](CFO) parallel to (001) [101](MgO), confirming the in-plane aligned polarization of PTO. The perpendicular magnetic anisotropy of this thin film results from the magnetoelastic anisotropy that exceeds the shape anisotropy. The increased frequency and the enhanced intensity of the tetrahedral (T-) site phonon modes by increasing the magnetic field indicate strong magnetoelastic coupling through magnetostriction in this multiferroic nanostructure. The anisotropic Raman strength enhancement of the T-site phonon along different directions suggests the magnetoelastic coupling is most efficient in the in-plane direction. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4800069]