Browsing by Issue Date, starting with "2001-02-01"

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Interface induced uphill diffusion of boron: An effective approach for ultrashallow junction
(2001-02-01)
Wang, HCH
;
Wang, CC
;
Chang, CS
;
Wang, TH
;
Griffin, PB
This paper investigates anomalous diffusion behavior for ultra low energy implants in the extension or tip of PMOS devices. Transient enhanced diffusion (TED) is minimal at these low energies, since excess interstitials are very close to the surface, Instead, interface induced uphill diffusion is found, for the first time, to dominate during low temperature thermal cycles. The interface pile-up dynamics can be taken advantage of to produce shallower junctions and improve short channel effect control in PMOS devices, Attempts to minimize TED before spacer deposition by inclusion of extra RTA. anneals are shown to be detrimental to forming boron ultra shallow junctions.
Differential capacitance measurements of relaxation-induced defects in InGaAs/GaAs Schottky diodes
(2001-02-01)
Chen, JF
;
Chen, NC
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Wang, JS
;
Chen, YF
;
電子物理學系
The use of a differential capacitance technique for characterizing the relaxation-induced defect states in Schottky diodes has been studied, Based on a proposed equivalent circuit including the effect of potential drop across the carrier-depletion layer, a simple equation of capacitance at different voltages and frequencies is derived and compared with experimental data obtained from relaxed In0.2Ga0.8As/GaAs samples, It is shown that the carrier-depletion layer will introduce capacitance dispersion over frequency like traps; from it the device's geometric parameters, the resistance of the carrier-depletion lager and the ionization energy of the deep level that gives rise to this resistance can be obtained. The relation between the low-frequency capacitance and reverse voltage can be well explained by the depletion of the free carriers between the Schottky depletion and the carrier-depletion layer The relaxation-induced traps are believed to be at 0.535 and 0.36 eV, respectively, in the GaAs and In0.2Ga0.8As regions.
Mode control of vertical-cavity surface-emitting lasers by germanium coating
(2001-02-01)
Chiou, SW
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Lin, G
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Lee, CP
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Yang, HP
;
Sung, CP
We have successfully developed a selective surface coating technique to control the modal behavior of the ion-implanted vertical-cavity surface-emitting laser (VCSEL). With selective deposition of a germanium coating by the lift-off process, we could spatially control the threshold gain condition of the VCSEL to support the single transverse mode. The threshold current is 7 mA and single transverse mode operation is maintained up to I mW. The method is simple and nondestructive compared with other techniques.
Obstacle avoidance in person following for vision-based autonomous land vehicle guidance using vehicle location estimation and quadratic pattern classifier
(2001-02-01)
Ku, CH
;
Tsai, WH
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資訊工程學系
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Department of Computer Science
An obstacle avoidance method for use in person following for vision-based autonomous land vehicle (ALV) guidance is proposed. This method is based on the use of vehicle location estimation and a quadratic pattern classifier, and aims to guide the ALV to follow a walking person in front by navigating along a derived collision-free path. Before generating the collision-free path, the person's location is obtained from extracted objects in the image by a person detection method. The object closest to a predicted person location is regarded as the followed person and the remaining objects are regarded as obstacles. The collision-free navigation path is designed for ALV guidance in such a way that the ALV not only can keep following the person but also can avoid collision with nearby obstacles. The navigation path results from a quadratic classifier that uses the vehicle and all of the objects in the image as input patterns. A turn angle is then computed to drive the ALV to follow the navigation path. Successful navigation sessions confirm the feasibility of the approach.
High quality interpoly-oxynitride grown by NH3 nitridation and N2O RTA treatment
(2001-02-01)
Pan, TM
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Lei, TF
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Yang, WL
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Cheng, CM
;
Chao, TS
In this letter, a method to grow high quality interpolysilicon-oxynitride (interpoly-oxynitride) film is proposed. Samples, nitridized by NH3 with additional N2O annealing and CVD TEOS deposited on poly-oxynitride (poly-I) with RTA NaO oxidation, show excellent electrical properties in terms of very high electric breakdown field, ion; leakage current, high charge to breakdown, and low electron trapping rate. This novel film is a good candidate for an interpoly dielectric of future high density EEPROM and flash memory devices.
Incorporating error shaping technique into LSF vector quantization
(2001-02-01)
Nein, HW
;
Lin, CT
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電控工程研究所
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Institute of Electrical and Control Engineering
This paper presents an error shaping technique for line spectrum frequency (LSF) vector quantization, The error shaping technique based on the weighted logarithm spectral distortion (WLSD) measure can be used for shaping the spectral distortion distribution of quantization error into any different curve depending on what kind of weighting function is used. However, the high computational complexity of the WLSD measure deters this error shaping technique from practical use. To solve this problem, we approximate the WLSD measure by the quadratically weighted measure or the weighted mean squared error (WMSE) measure and propose an optimal error shaping technique of LSF vector quantization. In this proposed error shaping technique, the optimal WMSE weights (i.e., the optimal weights of LSF parameters) are determined based on the theoretical analysis of the WLSD measure. Three experiments are performed to check the performance of the proposed error shaping technique. One experiment is set up by incorporating human perception into the LSF quantization and another is set up by emphasizing the human-sensitivity frequency band in lower frequency bandwidth 0-3 kHz. In the third experiment, we apply the proposed error shaping technique to the LSF quantization of a CELP coder to test how it affects the overall speech quality in an actual speech coding algorithm.
1.55-mu m and infrared-band photoresponsivity of a Schottky barrier porous silicon photodetector
(2001-02-01)
Lee, MK
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Chu, CH
;
Wang, YH
;
Sze, SM
;
電子工程學系及電子研究所
We have investigated the spectral responsivity of porous silicon Schottky barrier photodetectors in the wavelength range 0.4-1.7 mum The photodetectors show strong photoresponsivity in both the visible and the infrared bands, especially at 1.55 mum. The photocurrent can reach 1.8 mA at a reverse bias of 6 V under illumination by a 1.55-mum, 10-mW laser diode. The corresponding quantum efficiency is 14.4%. (C) 2001 Optical Society of America.
A note on optimal policies for a periodic inventory system with emergency orders
(2001-02-01)
Chiang, C
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管理科學系
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Department of Management Science
In this article, we develop a dynamic programming model for a periodic review inventory system in which emergency orders can be placed at the start of each period, while regular orders are placed at the beginning of an order cycle (which consists of a number of periods). We assume that the regular and emergency supply lead times differ by one period. We devise a simple algorithm of computing the optimal policy parameters. Thus, the ordering policy developed is easy to implement.
Discovering anomalies in access modifiers in Java with a formal specification
(2001-02-01)
Yang, W
;
交大名義發表
;
National Chiao Tung University
The Java programming language provides three access modifiers to control the visibility of the members of a class. Though identifying the weaknesses of the access modifiers from the informal semantics stated in the language manual is difficult, this does not mean that the access modifiers provide a sound ground for building secure programs. A rigorous study of the access modifiers with attribute grammars has uncovered several situations that are irregular or counterintuitive. These situations are confusing to programmers and may create weaknesses in Java programs.
Bayesian analysis of a growth curve model with power transformation, random effects and AR(1) dependence
(2001-02-01)
Lee, JC
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Lien, WH
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統計學研究所
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Institute of Statistics
In this paper we devote ourselves to a general growth curve model with power transformation, random effects and AR(1) dependence via a Bayesian approach. Two priors are proposed and both parameter estimation and prediction of future values are considered. Some numerical results with a set of real data are also given.
Behaviors of negative resistances and its influences on VCO design
(2001-02-01)
Kao, YH
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Wu, TH
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傳播研究所
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Institute of Communication Studies
The features of the negative resistance in common source and common gate FET configurations for wideband VCO are studied. They are also explained by the simplified three-capacitor model. A design procedure is then developed. The results are applied to a design of wide band oscillator at the several gigahertz region.
Photo-alignment of liquid crystals using a crosslinked discotic film
(2001-02-01)
Wu, LH
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Lee, WC
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Hsu, CS
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Wu, ST
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應用化學系
A new photo-alignment layer using a crosslinked discotic compound was demonstrated. This discotic compound exhibits excellent solubility in common organic solvents, the possibility of low temperature processing and good thermal stability. A linearly polarized long wavelength ultraviolet (LPUV) light (lambda = 350 nm) was used to initiate the crosslinking process and induce liquid crystal alignment on the discotic film surface. The induced LC directors were found parallel to the electric field direction of the LPUV light. A 1.2 degrees pre-tilt angle was achieved using a single exposure at a 30 degrees oblique angle.
Effects of incoherent processes on the quantum transport through a finite-range time-modulated potential
(2001-02-01)
Liang, HC
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Chu, CS
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電子物理學系
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Department of Electrophysics
We study the effect of phase randomization on the quantum transport through a finite-range time-modulated potential. The time-modulated potential leads only to coherent inelastic scatterings, and the incoherent processes are described by an S-matrix model proposed originally by Buttiker for the case of time-independent transport. This S-matrix model provides us a systematic way to reinject into the system those electrons that have suffered with incoherent scatterings. The distribution of these reinjected electrons is determined by an effective chemical potential <()over tilde>. For comparison, we study the cases where the incoherent processes occur inside and outside the time-modulated region. The incoherent processes are found to broaden and to smear the structures in the conductance G that are associated with the coherent inelastic scatterings. However, the smearing is more effective when the incoherent processes occur inside the time-modulated potential region.
Biotreatment of hydrogen sulfide- and ammonia-containing waste gases by fluidized bed bioreactor
(2001-02-01)
Chung, YC
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Huang, CP
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Liu, CH
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Bai, HL
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環境工程研究所
Gas mixtures of H2S and NH3 are the focus of this study of research concerning gases generated from animal husbandry and treatments of anaerobic wastewater lagoons. A heterotrophic microflora (a mixture of Pseudomonas putida for H2S and Arthrobacter oxydans for NH3) was immobilized with Ca-alginate and packed into a fluidized bed reactor to simultaneously decompose H2S and NH3. This bioreactor was continuously supplied with H2S and NH3 separately or together at various ratios. The removal efficiency, removal rate, and metabolic product of the bioreactor were studied. The results showed that the efficiency remained above 95% when the inlet H2S concentration was below 30 ppm at 36 L/hr. Furthermore, the apparent maximum removal and the apparent half-saturation constant were 7.0 x 10(-8) gS/cell/day and 76.2 ppm, respectively, in this study. The element sulfur as a main product prevented acidification of the biofilter, which maintained the stability of the operation. As for NH3, the greater than 90% removal rate was achieved as long as the inlet concentration was controlled below 100 ppm at a flow rate of 27 L/hr. In the NH3 inlet, the apparent maximum removal and the apparent half-saturation constant were 1.88 x 10(-6) g-N/cell/day and 30.5 ppm, respectively. Kinetic analysis showed that 60 ppm of NH3 significantly suppressed the H2S removal by Pseudomonas putida, but H2S in the range of 5-60 ppm did not affect NH3 removal by Arthrobacter oxydans. Results from bioaerosol analysis in the bioreactor suggest that the co-immobilized cell technique applied for gas removal creates less environmental impact.
Influence of a holistic color interval on color harmony
(2001-02-01)
Chuang, MC
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Ou, LC
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應用藝術研究所
;
Institute of Applied Arts
This study investigates how a holistic color interval i.e. the nondirectional color difference between a pair of colors in a CIELAB uniform color space, influences perceived color harmony. A set of 1035 test color pairs displayed on a CRT was evaluated for the degree of harmony. These test color years consist of pairs combined from among the selected 46 test colors evenly distributed in color space. The subjects were asked to select their three preferred colors from these 46 test colors and then to evaluate the degree of harmony of the test color combinations. The color intervals (DeltaE(ab)*) of each test color combination were calculated and treated as values of a independent variable. In addition, the evaluated degrees of color harmony were considered as values of a dependent variable, in which statistical analysis confirmed the relationship: the degree of harmony is a cubic function of the color interval. Moreover; the plot of this relationship allowed us to identify four color intervals: roughly corresponding to the regions of first ambiguity, similarity, second ambiguity, and contrast in Moon and Spencer's model. However, our results indicated that Moon and Spencer's principles for classifying harmonious/disharmonious regions in ten,ls of the color interval for three color attributes-lightness, chroma and hue-may be inappropriate in predicting perceived color harmony. As for the color intervals between a pair of colors considered as a function of the three attributes, the interval for lightness may have a predominant effect on color harmony, expressed in terms of a cubic relationship Results of the study further demonstrated that the subject's choice of colors significantly influences perceived color harmony. (C) 2001 John Wiley & Sons, Inc.
A new approach of group-based VLC codec system with full table programmability
(2001-02-01)
Shieh, BJ
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Lee, YS
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Lee, CY
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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
In this paper, the algorithm and architecture of a variable-length-code (VLC) codec system using a new group-based approach and achieving full table programmability are presented. According to the proposed codeword grouping and symbol memory mapping, both group searching and encoding/decoding procedures are completed by applying numerical properties and arithmetic operations to codewords and symbol addresses, By a novel symbol conversion, the memory requirement of the encoding process is reduced and the programmability of codewords and symbols is achieved, For MPEG applications, a 0.6-mum CMOS design that performs concurrent VLC codec processes is shown. This VLSI implementation occupies an area of 5.0 x 4.5 mm(2) with 110 k transistors and satisfies a coding table up to 256-entry 12-bit symbols and 16-bit codewords, In addition, both encoding and decoding throughputs of this design achieve 100 Msymbols/s at a 100-MHz clock rate. Therefore, the proposed VLC codec system is suitable for applications which require high operation throughput, such as HDTV, and simultaneous compression and decompression, such as videoconferencing.
Second-order delta-sigma modulation with interfered reference
(2001-02-01)
Huang, YC
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Wey, WS
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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
A delta-sigma (Delta Sigma) modulator has been traditionally analyzed by assuming its reference to be constant, but practically the reference may be interfered and thus vary with time. For an interfered reference modulator, the performance of quantization noise is degraded by quantization noise leakage due to interfered feedback. In this paper, a systematic study for observing the behavior of a second-order modulator with an interfered references is presented, based on a linear modeling, spectral analysis, and beharioral simulations. An analytical form of the output of a a Delta Sigma modulator with an interfered feedback is obtained and compared with behavioral simulation. Due to the agreement between the theoretical calculation and the behavioral simulation results, it is concluded that the quantization noise leakage should be considered for describing the behavior of the Delta Sigma modulators more precisely.
Effects of ceramic processing parameters on the microstructure and dielectric properties of (Ba1-xCax)(Ti0.99-y, ZryMn0.01)O-3 sintered in a reducing atmosphere
(2001-02-01)
Lee, WH
;
Tseng, TY
;
Hennings, D
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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
The effect of A/B ratio, sintering temperature, and oxygen partial pressure on microstructure and ceramic dielectric properties of 1 mol % MnO2 doped (Ba,Ca)(Ti,Zr,)O-3 sintered in a reducing atmosphere were investigated. Microstructure is found to be closely related to processing parameters. With decreasing A/B ratio, decreasing oxygen partial pressure and increasing sintering temperature, grain growth is enhanced. Concurrent with the grain size reduction, the crystal structure transformed from tetragonal to pseudocubic at room temperature and the dielectric constant, the dissipation factor and Curie point all decreased. However, the effects of grain size give a marked discrepancy on breakdown. The effect of A/B ratio and sintering temperature both suggest that breakdown voltage is decreased with increasing grain size. However, the breakdown voltage in relation to grain size by changing the oxygen partial pressure seems to show no significant difference. (C) 2001 Kluwer Academic Publishers.
Extended Gauss-Markov theorem for nonparametric mixed-effects models
(2001-02-01)
Huang, SY
;
Lu, HHS
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交大名義發表
;
National Chiao Tung University
The Gauss-Markov theorem provides a golden standard for constructing the best linear unbiased estimation for linear models. The main purpose of this article is to extend the Gauss-Markov theorem to include nonparametric mixed-effects models. The extended Gauss-Markov estimation (or prediction) is shown to be equivalent to a regularization method and its minimaxity is addressed. The resulting Gauss-Markov estimation serves as an oracle to guide the exploration for effective nonlinear estimators adaptively. Various examples are discussed. Particularly, the wavelet nonparametric regression example and its connection with a Sobolev regularization is presented. (C) 2001 Academic Press.
Characterization of hot-hole injection induced SILC and related disturbs in flash memories
(2001-02-01)
Yih, CM
;
Ho, ZH
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Liang, MS
;
Chung, SS
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電子工程學系及電子研究所
In this paper, we have proposed a new method for the study of disturb failure mechanisms caused by stress induced leakage current (SILC) in source-side erased flash memories. This method is able to directly separate the individual components of SILC due to either carrier charging/disharging in the oxide or the positive charge/trap assisted electron tunneling into the floating gate, In addition, the present method is very sensitive with capability of measuring ultralow current (<10(-19) A), Results show that, at low oxide field, the disturb is mainly contributed by the so-called charging/disharging of carriers into/from the oxide due to the capacitance coupling effect. While at high oxide field, the positive charge/trap assisted electron tunneling induced floating-gate charge variation is the major cause of disturb failure.