Browsing by Author "Chen, HY"

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A new method to extract MOSFET threshold voltage, effective channel length, and channel mobility using S-parameter measurement
(2004-05-01)
Chen, HY
;
Chen, KM
;
Huang, GW
;
Chang, CY
;
Huang, TY
In this work, a simple method for extracting MOSFET threshold voltage, effective channel length and channel mobility by using S-parameter measurement is presented. In the new method, the dependence between the channel conductivity and applied gate voltage of the MOSFET device is cleverly utilized to extract the threshold voltage, while biasing the drain node of the device at zero voltage during measurement. Moreover, the effective channel length and channel mobility can also be obtained with the same measurement. Furthermore, all the physical parameters can be extracted directly on the modeling devices without relying on specifically designed test devices. Most important of all, only one S-parameter measurement is required for each device under test (DUT), making the proposed extraction method promising for automatic measurement applications.
A novel approach for parameter determination of HBT small-signal equivalent circuit
(2005-06-01)
Chen, HY
;
Chen, KM
;
Huang, GW
;
Chang, CY
;
電子工程學系及電子研究所
Direct parameter extraction is believed to be the most accurate method for equivalent-circuits modeling of heterojunction bipolar transistors (HBT's). Using this method, the parasitic elements, followed by the intrinsic elements, are determined analytically. Therefore, the quality of the extrinsic elements extraction plays an important role in the accuracy and robustness of the entire extraction algorithm. This study proposes a novel extraction method for the extrinsic elements, which have been proven to be strongly correlated with the intrinsic elements. By utilizing the specific correlation. the equivalent circuit modeling is reduced to an optimistation problem of determining six specific extrinsic elements. Converting the intrinsic equivalent circuit into its common-col lector configuration, all intrinsic circuit elements are extracted using exact closed-form equations for both the hybrid-pi and the T-topology equivalent circuits. Additionally, a general explicit equation on the total extrinsic elements is derived, subsequently reducing the number of optimization variables. The modeling results are presented, showing that the proposed method can yield a good fit between the measured and calculated S parameters.
A novel erase scheme to suppress overerasure in a scaled 2-bit nitride storage flash memory cell
(2004-09-01)
Yeh, CC
;
Wang, TH
;
Tsai, WJ
;
Lu, TC
;
Liao, YY
The cause of over-erasure in a two-bit nitride storage Flash memory cell is investigated. Extra positive charges accumulated above the n(+) unction and channel-shortening enhanced drain-induced barrier lowering effect are found to be responsible for threshold voltage (V-t) lowering in an over-erased cell. A modified erase scheme is proposed to resolve this issue. By applying a source voltage during erase, the erase speed can be well controlled for cells with different channel lengths and a wide range of program-state Vt distribution, which will reduce overerasure significantly.
A product-coded WDM coding system
(1996-01-01)
Kao, MS
;
Chen, HY
;
Lin, D
;
電信工程研究所
;
電信研究中心
Forward error correction is a feasible approach to decline the bit error floor of lightwave systems, arising from the fact that a simple single-error-correcting code can reduce the error floor from O(P-e) to O(P-e(2)). Here we propose a novel wavelength demultiplexer (WDM) coding system using product code to improve performances of WDM systems with an error floor caused by fiber dispersion or system noises.
An assessment of single-electron effects in multiple-gate SOI MOSFETs with 1.6-nm gate oxide near room temperature
(2006-03-01)
Lee, W
;
Su, P
;
Chen, HY
;
Chang, CY
;
Su, KW
This letter provides an assessment of single-electron effects in ultrashort multiple-gate silicon-on-insulator (SOI) MOSFETs with 1.6-nm gate oxide. Coulomb blockade oscillations have been observed at room temperature for gate bias as low as 0.2 V. The charging energy, which is about 17 meV for devices with 30-nm gate length, may be modulated by the gate geometry. The multiple-gate SOI MOSFET, with its main advantage in the suppression of short-channel effects for CMOS scaling, presents a very promising scheme to build room-temperature single-electron transistors with standard silicon nanoelectronics process.
An improved approach for small-signal equivalent-circuit parameter determination of InGaP/GaAs HBT
(2005-03-05)
Chen, HY
;
Chen, KM
;
Huang, GW
;
Chang, CY
;
Huang, TY
In this paper, an improved method for extracting the small-signal equivalent-circuit elements of an HBT is proposed. A more general HBT equivalent circuit and a more general explicit equation on the total extrinsic elements are introduced. Linear least-square algorithms are cleverly adopted to reduce the number of error function. As a result, the modified approach can yield a better fit between the measured and simulated S-parameters over the conventional method. (C) 2005 Wiley Periodicals, Inc.
An improved parameter-extraction method of SiGe HBTs' substrate network
(2006-06-01)
Chen, HY
;
Chen, KM
;
Huang, GW
;
Chang, CY
;
電子工程學系及電子研究所
In this letter, an improved method for substrate network parameter extraction of SiGe heterojunction bipolar transistors (HBTs) is proposed. It is found that, without taking the intrinsic circuit elements into consideration, the conductance of substrate network will be underestimated while the susceptance of substrate network will be overestimated. Therefore, an iteration procedure is developed,to determine the intrinsic circuit elements of SiGe HBTs first. The intrinsic circuit elements are then applied to remove their influence on the substrate network parameter extraction. Compared with the conventional method, the proposed one can avoid some unphysical modeling results and provide reliable substrate network parameters.
Capillary electrophoresis, potentiometric and laser excited luminescence studies of lanthanide(III) complexes of 1,7-dicarboxymethyl-1,4,7,10-tetraazacyclododecane (DO2A)
(1998-10-07)
Chang, CA
;
Chen, YH
;
Chen, HY
;
Shieh, FK
;
生物科技學系
The protonation constants of the ligand 1,7-dicarboxymethyl-1,4,7,10-tetraazacyclododecane (DO2A) were redetermined by the potentiometric pH titration method (log K 10.94, 9.55, 3.85, 2.55) and the macrocycle ring protonation sites have also been confirmed by NMR techniques to be the secondary amine nitrogen atoms. The stability constants of calcium(II) and all trivalent lanthanide (Ln(3+)) metal complexes of DO2A (Ca2+, log K-ML 7.16; Ln(3+), log K-ML 10.94-13.31) were determined by the potentiometric pH titration and capillary electrophoresis methods, respectively. In general, the stabilities of the Ln(DO2A)(+) complexes increase with increasing atomic number for the lighter lanthanides (La3+-Sm3+) and remain relatively unchanged for the heavier lanthanides (Eu3+-Lu3+). Laser-excited spectroscopy of the F-7(o) --> D-5(o) transition of Eu3+ is used to study the aqueous Eu3+-DO2A complex system. At low pH (e.g. pH 5-6) Eu3+ forms a 1:1 species with the ligand DO2A, presumably Eu(DO2A)(H2O)(q)(+), where q is the number of inner-sphere coordinated water molecules. As the solution pH increases the hydrolysis product, Eu(DO2A)(OH)(H2O)(q-1), is formed. Lifetime measurements of each species in H2O and D2O allow the determination of the corresponding number of inner-sphere coordinated water molecules to be 3.0 and 2.6, consistent with the proposed structures (i.e. q = 3). The first hydrolysis constant (pK(h)) is estimated to be 8.1 +/- 0.3.
Characterization of intact Penicillium spores by matrix-assisted laser desorption/ionization mass spectrometry
(2005)
Chen, HY
;
Chen, YC
;
應用化學系
;
Department of Applied Chemistry
The fungal spores of Penicillium expansum, P. chrysogenum, P. citrinum, P. digitatum, P. italicum, and P. pinophilum were characterized by using matrix-assisted laser desorption/ionization with time-of-flight mass spectrometry (MALDI-TOFMS). These fungal spores are frequently found in grain and fruit. The mass spectra of these six species were directly obtained from the intact spores without any pretreatment. The results obtained indicate that 2,5-dihydroxybenzoicacid and sinapinic acid are suitable matrices for the analysis of Penicillium spores. Characteristic ions representing the different species were obtained with sufficiently high reproducibility that these ions can be employed to identify the different fungal species. On the basis of these characteristic ions obtained from these authentic Penicillium spores, the approach was applied to characterize the fungal species contaminating the surfaces of fruit. It was demonstrated that the fungal spores directly scratched from the surfaces of fruit contaminated by unknown fungi can be rapidly identified using MALDI-TOFMS analysis without any tedious pretreatment. Copyright (c) 2005 John Wiley & Sons, Ltd.
Characterization of NH3 plasma-treated Ba0.7Sr0.3TiO3 thin films
(2000-04-01)
Wuu, DS
;
Horng, RH
;
Liao, FC
;
Leu, CC
;
Huang, TY
The effects of plasma surface treatment, using NH3 gas, of Ba0.7Sr0.3TiO3 (BST) films on the leakage and dielectric characteristics of a Pt/BST/Pt capacitor were investigated. As a result of the exposure of BST to the plasma, the leakage current density of the BST capacitor can be improved by three orders of magnitude as compared to that of the nonplasma-treated sample at an applied voltage of 1.5 V. Nevertheless, the surface morphology of BST was also changed by the NH3 plasma, as explored by atomic force microscopy. From the X-ray photoelectron spectroscopy examination, the existence of the N 1 s peak was observed in the plasma-treated sample. It induces the additional space charge and results in the reduction of the dielectric constant. (C) 2000 Elsevier Science Ltd. All rights reserved.
Computation of noise parameters using genetic algorithms
(2004)
Chen, HY
;
Chen, KM
;
Huang, GW
;
Cho, MH
;
Chang, CY
In this study, an improved computation method for the noise parameters of a linear noisy two-port network is introduced. A new error function, which considers noise figure and source admittance error simultaneously, is proposed to estimate the four noise parameters. The global optimization of the error function is searched directly by using a genetic algorithm.
Determination of stability constants of metal complexes by capillary electrophoresis
(1999-08-01)
Chang, CE
;
Chen, CY
;
Chen, HY
;
生物科技學系
;
Department of Biological Science and Technology
The stability constants of several divalent first row transition and trivalent lanthanide metal complexes were determined by capillary electrophoresis (CE) methods. Four different approaches, i.e. direct formation, ligand exchange, metal exchange and metal-ligand double exchange were developed. To verify if these CE methods are indeed applicable, the stability constant of CuHEDTA was re-determined to be 17.47 +/- 0.20 (consistent with the published 17.50) using the CuEDTA and ZnHEDTA metal-ligand double exchange approach. The stability constants of lanthanide (Ce3+ and Eu3+) and transition metal (Ni2+ and Zn2+) complexes of an aminopolycarboxylate ligand, DO2A (1,7-dicarboxymethyl-1,4,7, 10-tetraazacyclododecane) were measured under the direct complex formation condition. The stability constant of the NiDO2A complex was determined by the ligand exchange method using 1,4,8,11-tetraazaundecane (2,3,2-tet) as the competing ligand. The stability constant of CuDO2A complex was determined by the metal exchange method using Zn2+ ion as the competing metal ion, and complex formation competitions of Ni2+ and Cu2+ between DO2A and 2,3,2-tet were studied by the metal-ligand double exchange method. Effects of experimental conditions and the advantages and limitations of these CE methods are discussed.
Effects of O-2 plasma treatment on the electric and dielectric characteristics of Ba0.7Sr0.3TiO3 thin films
(2000-04-01)
Leu, CC
;
Chan, SH
;
Chen, HY
;
Horng, RH
;
Wuu, DS
The effects of the O-2 plasma treatment on the electric and dielectric characteristics of Ba0.7Sr0.3TiO3 (BST) thin films were investigated. As a result of the exposure of the as-deposited or the annealed BST films to the O-2 plasma, the leakage current density of the BST films can be improved. Typically, the leakage current density can decrease by three orders of magnitude as compared that of the non-plasma treated sample at an applied voltage of 1.5 V. It is found that the plasma treatment changes the surface morphology. The capacitance of the BST films was reduced by 10%similar to 30%. The improvement of the leakage current density and the reduction of a dielectric constant for the plasma treated samples could be attributed to the reduction of carbon contaminations of BST thin films. The 10 year life time of the time-dependent dielectric breakdown (TDDB) studies indicates that all the samples have a life time of over 10 years of operation at a voltage bias of 1 V. (C) 2000 Elsevier Science Ltd. Al rights reserved.
Iridium(III) complexes with orthometalated quinoxaline ligands: Subtle tuning of emission to the saturated red color
(2005-03-07)
Hwang, FM
;
Chen, HY
;
Chen, PS
;
Liu, CS
;
Chi, Y
Rational design and syntheses of four iridium complexes (1-4) bearing two substituted quinoxalines and an additional 5-(2-pyridyl) pyrazolate or triazolate as the third coordinating ligand are reported. Single-crystal X-ray diffraction studies of 1 reveal a distorted octahedral geometry, in which two dpqx ligands adopt an eclipse configuration, for which the quinoxaline N atoms and the C atoms of orthometalated phenyl groups are located at the mutual trans-and cis-positions, respectively. The lowest absorption band for all complexes consists of a mixture of heavy-atom Ir(III)-enhanced (MLCT)-M-3 and (3)pipi(*) transitions, and the phosphorescent peak wavelength can be fine-tuned to cover the spectral range of 622-649 nm with high quantum efficiencies. The cyclic voltarnmetry was measured, showing a reversible, metal-centered oxidation with potentials at 0.76-1.03 V, as well as two reversible reduction waves with potentials ranging from -1.61 to -2.06 V, attributed to the sequential addition of two electrons to the more electron-accepting heterocyclic portion of two distinctive cyclometalated CAN ligands. Complex 1 was used as the representative example to fabricate the red-emitting PLEDs by blending it into a PVK-PBD polymer mixture. The devices exhibited the characteristic emission profile of 1 with peak maxima located at 640 nm. The maximum external quantum efficiency was 3.15% ph/el with a brightness of 1751 cd/M-2 at a current density of 67.4 mA/cm(2) and the maximum brightness of 7750 cd/m(2) was achieved at the applied voltage of 21 V and with CIE coordinates of (0.64, 0.31).
Layout design of high-quality SOI varactor
(2003)
Chen, HY
;
Chen, KM
;
Huang, GW
;
Huang, CH
;
Yang, TH
This paper presents the geometry effect on the characteristics of accumulation type SOI varactor with Mesa-isolation technology. Constant gate area varactors with various geometry condition were implemented to investigate the effects of layout design parameters on overall varactor performance. Physical and mathematic analysis based on the measurement results show that parasitic capacitance at the edge of active region seriously degrads the device quality factor at smallest gate length. The optimized SOI varactor has a quality factor Q of about 150 /GHz/pF at medium gate length varactor. The experiment result can serve as a design reference for high-quality SOI varactors.
Linearity and power characteristics of SiGeHBTs at high temperatures for RF applications
(2005-07-01)
Chen, KM
;
Peng, AS
;
Huang, GW
;
Chen, HY
;
Huang, SY
In this paper, the power gain, power-added efficiency (PAE) and linearity of power SiGe heterojunction-bipolar transistors at various temperatures have been presented. The power characteristics were measured using a two-tone load-pull system. For transistors biased with fixed base voltage, the small-signal power gain and PAE of the devices increase with increasing temperature at low base voltages, while they decrease at high base voltages. Besides, the linearity is improved at high temperature for all voltage biases. However, for devices with fixed collector current, the small-signal power gain, PAE, and linearity are nearly unchanged with temperature. The temperature dependence of power and linearity characteristics can be understood by analyzing the cutoff frequency, the collector current, Kirk effect and nonlinearities of transconductance at different temperatures.
Noise parameters computation of microwave devices using genetic algorithms
(2005-07-01)
Chen, HY
;
Huang, GW
;
Chen, KM
;
Chang, CY
;
電子工程學系及電子研究所
In this letter, a new computation method for the noise parameters of a linear noisy two-port network is introduced. A new error function, which considers noise figure and source admittance error simultaneously, is proposed to estimate the four noise parameters. The global optimization of the error function is searched directly by using a genetic algorithm.
Optimization of second harmonic generation in non-linear film structure
(2004-06-01)
Dyankov, G
;
Chen, HY
;
Chao, S
;
Chi, S
;
光電工程學系
The problem about optimization of second harmonic generation (SHG) by a laser beam in a non-linear medium with dimensions less than the beam size has not been solved yet. We present a theoretical method providing an optimization of SHG in the case of non-linear film non-waveguide structure. We have found that even in the case of perfect phase matching there is an optimum length for maximum non-linear interaction. The dependence of generation efficiency on different type of non-linear profiles has been established and related with experimental results. (C) 2004 Elsevier B.V. All rights reserved.
Single- and multiepoch analyses of global positioning system baseline network: Application to coordinate and velocity determinations in Central Taiwan
(2004-05-01)
Hwang, CW
;
Lee, LH
;
Yu, SB
;
Chen, HY
;
土木工程學系
Theories and computer programs are developed for single- and multiepoch analyses of a global positioning system (GPS) baseline network using the datum-free and weighted constraint solutions. Single-epoch analysis is for evaluating data quality, removing outliers, examining network precision, and estimating coordinates. Multiepoch analysis is for simultaneously determining epoch coordinates and station velocities. The datum-free solution yields estimable data residuals and relative coordinates and is suitable for adjusting data only and for detecting changes of relative coordinates. The weighted constraint solution allows a lower-order network to be attached to an existing, higher-order network. The analysis methods are applied to a multiepoch GPS baseline network in central Taiwan, which was hit by the 1999 Chi-Chi earthquake measuring 7.3 on the Richter scale. The velocities computed by the methods developed in this study are consistent with those from the Bernese GPS software. The result of the multiepoch analysis indicates that, in the first year after the Chi-Chi earthquake, the crust east of the Chelungpu Fault moved northwestwards at a mean rate of about 10 cm/year, while the crust west of the Chelungpu Fault moved in the opposite direction at a much lower speed.
Synthesis and opto-electrical properties of stellar polyfluorene derivatives containing polyhedral oligomeric silsesquioxanes as the center core
(2006-06-01)
Chen, KB
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Chen, HY
;
Yang, SH
;
Hsu, CS
;
應用化學系
Three polyfluorene derivatives (P1-P3) emitting blue, green and red light were prepared via a Suzuki coupling method. Polyhedral oligomeric silsesquioxanes (POSS) were integrated into the center core of the derivatives to create stellar light-emitting polymers (POSS-P1-POSS-P3). The glass-transition and decomposition temperatures were raised after introducing POSS moieties. The starlike polymers showed a reduced emissive band at 540 nm when annealing at 200 degrees C. The result implies that integrated POSS at the center core suppresses the keto effect generally occurring for polyfluorenes. Double-layer light-emitting devices of indium tin oxide/poly(ethylenedioxythiophene)/polymer/Ca/Al were fabricated to evaluate polymer potential. Compared with pristine polymers, the maximum brightness and the current efficiency of devices using POSS-containing polymers as active layers were enhanced. A blending method using P1 or POSS-P1 as the host matrix further improved device performance.