Browsing by Issue Date, starting with "2005-09-22"

Now showing 1 - 20 of 65967

An interfacial investigation of high-dielectric constant material hafnium oxide on Si substrate
(2005-09-22)
Chen, SC
;
Lou, JC
;
Chien, CH
;
Liu, PT
;
Chang, TC
In this study, the hump in the capacitance-voltage (C-V) curves, variation of leakage current, interfacial layer increase, and electron trapping in non-surface treated hafnium oxide (HfO2) samples were observed and investigated. From the results of the investigation, it was found that both rapid thermal oxidation and NH3 surface treatments improved the C-V curves. In addition, it was observed that samples treated with ammonia exhibited a lower leakage current when compared with the others. From the results of the dielectric, leakage current study, a severe electron trapping effect was exhibited under higher electric field stress. Finally, the conduction mechanism in the HfO2 thin film was dominated by Frenkel-Poole emission in a high electric field. (c) 2005 Elsevier B.V All rights reserved.
The nitrogen doping effect on the properties of Ge-In-Sb-Te phase-change recording media investigated by blue-light laser
(2005-09-22)
Yeh, TT
;
Hsieh, TE
;
Shieh, HPD
;
材料科學與工程學系
;
光電工程學系
This work investigates the thermal, optical and recrystallization properties as well as the microstructure of nitrogen-doped Ge-In-Sb-Te (GIST) phase-change material when irradiated by blue-light laser. The experimental results showed that nitrogen doping at the condition of N-2/Ar sputtering gas flow ratio equals to 3% might enhance the recrystallization speed of GIST recording layer up to 1.5 times. However, the disk failed when too much nitrogen (N-2/Ar >= 5.0%) was introduced. The data obtained by differential scanning calorimetry, X-ray diffraction and ellipsometry revealed changes of thermal and optical properties due to the nitrogen doping in GIST. When appropriate amount of nitrogen was added, the activation energy (E-a) of amorphous-crystalline phase transition of GIST decreased and the optical constants of amorphous and crystalline phases (except the k value of amorphous phase) gradually reduced with the increase of wavelength in the range of 600-750 nm. Modulation simulation based on the reflectively of doped GIST layers obtained from static test indicated that appropriate nitrogen doping benefited the signal characteristics of optical disks. Transmission electron microscopy observed numerous tiny precipitates uniformly distributed in the doped GIST layers. These were believed to be nitride particles generated by nitrogen doping that might offer the preferential sites for amorphous-crystalline phase transition so that the recrystallization speed was accelerated. (c) 2005 Elsevier B.V. All rights reserved.
Efficient white organic light emitting devices with dual emitting layers
(2005-09-22)
Wu, YS
;
Hwang, SW
;
Chen, HH
;
Lee, MT
;
Shen, WJ
In this paper, a new white organic light-emitting device (OLED) with the structure of indium tin oxide/CFx/1,4-bis[N-(1-naphthyl)-N'-phenylamino]-biphenyl (NPB) (30 mn)NPB: 2,8-di(t-butyl)-5,11-di[4-(t-butyl)phenyl]-6,12-diphenylnaphthacene (20 nm; 1.6 %)/2-methyl-9,10-di(2-naphthyl) anthracene: p-bis(p-NN-di-phenyl-aminostyryl)benzene (40 nm, 3%)/aluminum tris(8-hydroxyquinoline) (20 nm)/LiF (1 nm)/Al (200 mn) has been investigated. The device showed white emission with a high-luminous yield of 9.75 cd/A at 20 mA/cm(2), but its Commission Internationale de l'Eclairage chromaticity coordinates appeared to change from (0.34, 0.42) at 6 mA/cm(2) to (0.27, 0.37) at 200 mA/cm(2) due to the shift of recombination zone. The change of color with drive current was suppressed by introduction of an electron-blocking layer of NPB along with a hole-blocking layer of aluminum (III) bis(2-methyl-8-quinolinato)4-phenylphenolato to the white OLED which successfully confined the recombination site and achieved a luminous yield of 9.9 cd/A at 20 mA/cm(2). (c) 2005 Elsevier B.V All rights reserved.
Motion associated with a single rouse segment versus the alpha relaxation. 2
(2005-09-22)
Lin, YH
;
應用化學系
;
Department of Applied Chemistry
The dynamics in polystyrene melt and concentrated solution as probed by depolarized photon-correlation spectroscopy has been shown to reflect the motion associated with a single Rouse segment. In the concentrated solution case (entanglement-free), the analysis using the frictional factor K (= zeta < b(2)>/kT pi(2)m(2)) extracted from the viscosity data in terms of the Rouse theory and aided by the Monte Carlo simulation based on the Langevin equation of the Rouse model confirms the conclusion in a precise manner. In the melt case (entangled), the Rouse-segmental motion as observed by depolarized photon-correlation spectroscopy is compared with the alpha relaxation and the highest Rouse-Mooney normal mode extracted from analyzing the creep compliance J(t) of sample A reported in the companion paper. Another well-justified way of defining the structural (alpha-) relaxation time is shown basically to be physically equivalent to the one used previously. On the basis of the analysis, an optimum choice tau(s) = 18 (G) ((G) being the average glassy-relaxation time) is made, reflecting both the temperature dependence of WG and the effect on the bulk mechanical property by the glassy-relaxation process. In terms of thus defined tau s, two traditional ways of defining the alpha-relaxation time are compared and evaluated. It is shown that as the temperature approaches the calorimetric T-g, two modes of temperature dependence are followed by the dynamic quantities concerning this study: One includes the time constant of the highest Rouse-Mooney normal mode, tau(v); the temperature dependence of the viscosity corrected for the changes in density and temperature, eta/rho T; and the average correlation time obtained by depolarized photoncorrelation spectroscopy, . The other, being steeper, is followed by the alpha-relaxation time tau(s) derived from the glassy-relaxation process and the temperature dependence of the recoverable compliance J(r)(t) as obtained by Plazek. The comparison of the dynamic quantities clearly differentiates the motion associated with a single Rouse segment as characterized by tau(v) or from the alpha-relaxation as characterized by tau(s); due to the lack of clear definition of these two types of motion in the past and the proximity of one to the other in the time scale-actually the two crossing over each other-as the temperature is approaching T-g, the two modes could be easily confused. Below similar to 110 degrees C, the rate of changing with temperature lags behind that of tau(v) is explained as due to the loss of effective ergodicity taking place in the system.
Whole range of chain dynamics in entangled polystyrene melts revealed from creep compliance: Thermorheological complexity between glassy-relaxation region and rubber-to-fluid region. 1
(2005-09-22)
Lin, YH
;
應用化學系
;
Department of Applied Chemistry
The rubber(like)-to-fluid region of the creep compliance J(t) results reported by Plazek of two nearly monodisperse polystyrene melts in the entanglement region have been quantitatively analyzed in terms of the extended reptation theory (ERT), giving the frictional factor K (= zeta < b(2)>/kT pi(2)m(2)) in quantitative agreement with the values obtained previously from analyzing the relaxation modulus G(t) line shapes as well as calculated from the viscosity and diffusion data-a quantity shown independent of molecular weight as expected from the theory. Using the successful description of J(t) in terms of ERT in the rubber(like)-to-fluid region as the reference-frame in time, the glassy-relaxation process pG(t) that occurs in the small-compliance short-time region of J(t) can be studied in perspective. As shown from the analysis in terms of a stretched exponential form for mu(G)(t) incorporated into ERT, the temperature dependence of the energetic interactions-derived mu(G)(t) process being stronger in a simple manner than that of the entropy-derived ERT processes accounts fully for the uneven thermorheological complexity occurring in J(t) as initially observed by Plazek. When the results of analysis being displayed in the G(t) form, the relative roles of the energetic interactions-derived dynamic process and the entropy-derived ones in polystyrene are clearly revealed. It is shown that at the calorimetric glass transition temperature (T-g) the contribution from energetic interactions among segments to G(t) at the time scale of the highest Rouse-Mooney normal mode greatly exceeds that derived from entropy, indicating vitrification at the Rouse-segmental level. At the same time the Rouse-Mooney normal modes provide an internal yardstick for estimating the characteristic length scale of a polymer at T-g, giving similar to 3 nm for polystyrene. On the basis of the obtained results, the basic mechanism for the thermorheological complexity occurring in polystyrene is analyzed. It is shown that this basic mechanism should be also responsible for. the breakdown of the Stoke-Einstein equation in relating the translational diffusion constant and viscosity as observed in glass-forming liquids, such as OTP and TNB, in approaching T-g from above.
拐杖牡丹
(2005-09-25)
管管
Improvement in light-output efficiency of near-ultraviolet InGaN-GaN LEDs fabricated on stripe patterned sapphire substrates
(2005-09-25)
Lee, YJ
;
Hsu, TC
;
Kuo, HC
;
Wang, SC
;
Yang, YL
InGaN/GaN multi-quantum wells near ultraviolet light-emitting diodes (LEDs) were fabricated on a patterned sapphire substrate (PSS) with parallel stripe along the (1100)(sapphire) direction by using low-pressure metal-organic chemical vapor deposition (MOCVD). The forward- and reverse-bias electrical characteristics of the stripe PSS LEDs are, respectively, similar and better than those of conventional LEDs on sapphire substrate. The output power of the epoxy package of stripe PSS LED was 20% higher than that of the conventional LEDs. The enhancement of output power is due not only to the reduction of dislocation density but also to the release of the guided light in LEDs by the geometric shape of the stripe PSS, according to the ray-tracing analysis. (c) 2005 Elsevier B.V. All rights reserved.
Singlemode InAs quantum dot photonic crystal VCSELs
(2005-09-29)
Yang, HPD
;
Chang, YH
;
Lai, FI
;
Yu, HC
;
Hsu, YJ
An InAs quantum dot photonic crystal vertical-cavity surface-emitting laser (QD PhC-VCSEL) for fibre-optic applications is first demonstrated. Single fundamental mode CW output power of 0.2 mW has been achieved in the 1300 nm range, with a threshold current of 4.75 mA. Side-mode suppression ratio larger than 40 dB has been observed over the entire thermally limited operation range.
Spin Hall effect on edge magnetization and electric conductance of a 2D semiconductor strip
(2005-09-30)
Mal'shukov, AG
;
Wang, LY
;
Chu, CS
;
Chao, KA
;
電子物理學系
The intrinsic spin Hall effect on spin accumulation and electric conductance in a diffusive regime of a 2D electron gas has been studied for a 2D strip of a finite width. It is shown that the spin polarization near the flanks of the strip, as well as the electric current in the longitudinal direction, exhibit damped oscillations as a function of the width and strength of the Dresselhaus spin-orbit interaction. Cubic terms of this interaction are crucial for spin accumulation near the edges. As expected, no effect on the spin accumulation and electric conductance have been found in case of Rashba spin-orbit interaction.
Defending against spoofed DDoS attacks with path fingerprint
(2005-10-01)
Lee, FY
;
Shieh, S
;
資訊工程學系
;
Department of Computer Science
In this paper, we propose anew scheme, called ANTI D, for detecting and filtering DDoS attacks which use spoofed packets to circumvent the conventional intrusion detection schemes. The proposed anti-DDoS scheme intends to complement, rather than replace conventional schemes. By embedding in each IP packet a unique path fingerprint that represents the route an IP packet has traversed, ANTID is able to distinguish IP packets that traverse different Internet paths. In ANTID, a server maintains for each of its communicating clients the mapping from the client's IP address to the corresponding path fingerprint. The construction and renewal of these mappings is performed in an on-demand fashion that helps to reduce the cost of maintenance. With presence of the mapping table, the onset of a spoofed DDoS attack can be detected by observing a surge of spoofed packets. Consequently, spoofed attack packets are filtered so as to sustain the quality of protected Internet services. ANTID is lightweight, robust, and incrementally deployable. Our experiment results showed that the proposed scheme can detect 99.95% spoofed IP packets and can discard them with little collateral damage to legitimate clients. It also showed that the higher the aggregated attack rate is, the sooner the attack can be detected. (C) 2005 Elsevier Ltd. All rights reserved.
Effects of channel width on electrical characteristics of polysilicon TFTs with multiple nanowire channels
(2005-10-01)
Wu, YC
;
Chang, TC
;
Liu, PT
;
Chen, CS
;
Tu, CH
This brief studies the electrical characteristics of a series of polysilicon thin-film transistors (poly-Si TFTs) with different numbers of multiple channels of various widths, with lightly doped drain (LDD) structures. The nanoscale TFT with ten 67-nm-wide split channels (M10) has superior and more uniform electrical characteristics than other TFTs. Additionally, experimental results reveal that the electrical performance of proposed TFTs enhances with each channel width decreasing, yielding a profile from a single-gate to tri-gate structure.
Electrochemical study on screen-printed carbon electrodes with modification by iron nanoparticles in Fe(CN)(6)(4-/3-) redox system
(2005-10-01)
Lee, SH
;
Fang, HY
;
Chen, WC
;
Lin, HM
;
Chang, CA
The remarkable enhancement of electron transfer on screen-printed carbon electrodes (SPCEs) with modification by iron nanoparticles (Fe-nano), coupled with Fe(CN)(6)(4-/3-) redox species, was characterized with an increase of electroactive area (A(ea)) at electrode surface together with a decrease of heterogeneous. electron transfer rate constant (k degrees) in the system. Hence, Fe-nano-Fe(CN)(6)(3-) SPCEs with deposition of glucose oxidase (GOD) demonstrated a higher sensitivity to various glucose concentrations than Fe(CN)(6)(3-)/GOD-deposited SPCEs. In addition, an inhibited diffusion current from cyclic voltammograms was also observed with an increase in redox concentration and complicated the estimation of A(ea). Further analysis by the electrochemical impedance method, it was shown that this effect might be resulted from the electrode surface blocking by the products of activated complex decomposition.
Novel single-poly EEPROM with damascene control-gate structure
(2005-10-01)
Sung, HC
;
Lei, TF
;
Hsu, TH
;
Wang, SW
;
Kao, YC
A novel single-poly EEPROM using damascene control gate (CG) structure is presented in this letter. The CG is tungsten (W) line made by a damascene process, and intergate dielectric is Al2O3 grown by atomic layer deposition (ALD). The program and erase mechanism is the same as the one for traditional stacked-gate cell, which uses the channel hot electron injection for programming and Fowler-Nordheim tunneling for channel erasing. With the high dielectric constant (K) property of Al2O3, we can perform the program and erase function with a voltage less than 6.5 V, which can be handled by 3.3 V devices instead of traditional high voltage devices. In the process compatibility aspect, this new cell needs only two extra masking steps over the standard CMOS process, and the high-kappa material is deposited in the back-end metallization steps without the contamination concerns on the front-end process. Therefore, this new technology is suitable for embedded application. In this letter, the good cell performance is demonstrated; such as, fast programming/erasing, good endurance and data retention.
Tunable deep-ultraviolet source generated by scattering off adiabatically prepared Raman coherence in hydrogen gas
(2005-10-01)
Chen, WJ
;
Kung, AH
;
光電工程學系
;
Department of Photonics
We demonstrate a tunable deep-ultraviolet coherent source generated by the beating of a tunable UV laser and strongly driven vibrational Raman coherence in hydrogen. The total energy conversion efficiency reaches a maximum of 50% at the phase side of the Raman coherence. The generated spectrum of Raman sidebands tunes with the input and extends from 435 to 146 nm for an input at 282 nm. (c) 2005 Optical Society of America.
Special section on papers presented at IDMC '05 - Introduction
(2005-10-01)
Shieh, HPD
;
Wu, IW
;
顯示科技研究所
;
Institute of Display
小孩
(2005-10-01)
管管
小孩
(2005-10-01)
管管
Optimal design of CMOS pseudoactive pixel sensor (PAPS) structure for low-dark-current and large-array-size imager applications
(2005-10-01)
Shih, YC
;
Wu, CY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this paper, a pixel structure called the optimal pseudoactive pixel sensor (OPAPS) is proposed and analyzed for the applications of CMOS imagers. The shared zero-biased-buffer in the pixel is used to suppress both dark current of photodiode and leakage current of pixel switches by keeping both biases of photodiode and parasitic pn junctions in the pixel bus at zero voltage or near zero voltage. The factor of photocurrent-to-dark-current ratio per pixel area (PDRPA) is defined to characterize the performance of the OPAPS structure. It is found that a zero-biased-buffer shared by four pixels can achieve the highest PDRPA. In addition, the column sampling circuits and output correlated double sampling circuits are also used to suppress fixed-pattern noise, clock feedthrough noise, and channel charge injection. An experimental chip of the proposed OPAPS CMOS imager with the format of 352 x 288 (CIF) has been designed and fabricated by using 0.25-mu m single-poly-five-level-metal (1P5M) N-well CMOS process. In the fabricated CMOS imager, one shared zero-biased-buffer is used for four pixels where the PDRPA is equal to 47.29 mu m(-2). The fabricated OPAPS CMOS imager has a pixel size of 8.2 x 8.2 mu m, fill factor of 42%, and chip size of 3630 x 3390 mu m. Moreover, the measured maximum frame rate is 30 frames/s and the dark current is 82 pA/cm(2). Additionally, the measured optical dynamic range is 65 dB. It is found that the proposed OPAPS structure has lower dark current and higher optical dynamic range as compared with the active pixel sensor (APS) and the conventional passive pixel sensor (PPS). Thus, the proposed OPAPS structure has high potential for the applications of high-quality and large-array-size CMOS imagers.
從代理理論的角度探討董事會特性、股權結構與負債之關聯性
(2005-10-01)
洪榮華
;
陳香如
;
柯璟瑩
;
Jung-Hua Hung
;
Hsiang-Ju Chen
本文從代理問題的角度，檢視董事會特性及股權結構與負債之關聯性，同時探討負債、內部人持股、機構人持股與股利政策等監督機制之替代效果，並進一步驗證集團與非集團企業之差異性。以上市公司為對象，資料從1995到2001年，透過聯立模型以3SLS實證發現：(1)內部人持股、機構人持股與負債間互呈顯著正相關，符合管理據守、利益衝突與策略合力假說；其他股權結構、董事會特性變數與負債間則多不顯著，顯示國內公司治理尚有很大的進步空間。(2)股利與負債政策間互呈顯著負相關，兩者為替代的監督機制。(3)集團與非集團樣本可能因融資方式與條件不同，而有不同的融資考量。
An automatic pin identification method for a three-phase DC brushless motor
(2005-10-01)
Wang, SJ
;
Cheng, CC
;
Lin, SK
;
Ju, JJ
;
Huang, DR
The pin identification is to find the definition of each connecting pin of a three-phase brushless motor. The 11 pins of the motor can be distinguished into three groups by a simple resistance measurement method. An automatic method has two steps. In the first step, the motor is in an open-circuited mode; and the individual pins of the windings are identified by comparing back electromotive forces. A special integral is defined and used to match Hall signal pins with the Hall sensors. The polarity of each pair of the Hall signal pins is determined by the second step of a standstill method. The proposed method is illustrated and verified by an experiment.