Browsing by Author "TSAI, JY"

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2 NEW GENERALIZED EQUATIONS FOR MINORITY-CARRIER TRANSPORT IN BIPOLAR-TRANSISTORS WITH HEAVILY DOPED BASE AND NONUNIFORM BAND-STRUCTURE
(1992-06-01)
CHANG, KM
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TSAI, JY
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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
Two new, simple, general and rigorous closed-form integral solutions to the base current density and to the base transit time for electron transport in NPN bipolar transistors with heavily doped base and non-uniform band structure are presented. The expressions include the effects of non-uniform band structure, the influence of Fermi-Dirac statistics, the position-dependent mobility and the velocity saturation effect at the base-collector depletion-layer edge on the base side. An application of this new simplified base current density of equation to Early voltage in a narrow-base bipolar transistor is illustrated. A simple example for the effects of the minority-carrier density and of the base built-in field on the minority-carrier base transit time is also qualitatively discussed.
EFFECT OF FLUORINE INCORPORATION ON THE THERMAL-STABILITY OF PTSI/SI STRUCTURE
(1993-01-01)
TSUI, BY
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TSAI, JY
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WU, TS
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CHEN, MC
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交大名義發表
The effect of fluorine incorporation on PtSi/Si structure is studied systematically. It is observed that the fluorine incorporation from ion implantation improves the high-temperature stability of the PtSi/Si structure. The optimum implantation energy is determined to be the energy at which the maximum percentage of the as-implanted fluorine ion locates at the PtSi/Si interface region. The SIMS analysis shows that the fluorine atom piles up at the PtSi/Si interface. The XPS analysis indicates that the fluorine atoms at the PtSi/Si interface are bonded to the silicon atoms in a form of SiF2 or SiF3. A fluorine-buffer (FB) model is proposed to explain the effect of fluorine incorporation. It is postulated that the Si-F layer acts as a buffer layer to change the PtSi/Si interface energy and preserve the integrity of the silicide layer at high temperature. Fluorinated Schottky junctions are fabricated and the electrical characteristics show that the sustainable process temperature can be improved from 650-degrees-C for the unfluorinated Schottky junctions to higher than 800-degrees-C for the fluorinated Schottky junctions.
FORMATION OF PTSI-CONTACTED P+N SHALLOW JUNCTIONS BY BF2+ IMPLANTATION AND LOW-TEMPERATURE FURNACE ANNEALING
(1991-04-15)
TSUI, BY
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TSAI, JY
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CHEN, MC
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This work investigates the characteristics of PtSi-silicided p+n shallow junctions fabricated by implanting BF2+ ions into either the Pt/Si (ITM scheme) or the PtSi/Si (ITS scheme) structure followed by annealing in N2 furnace at temperatures from 650 to 800-degrees-C. For a structure with Pt film of 30 nm thickness or PtSi film of 60 nm thickness, the implantation energy ranges from 40 to 80 keV with a dose ranging from 1 x 10(15) to 1 x 10(16) cm-2. For the ITS samples with BF2+ implantation at 40 keV, all ions are confined in the PtSi layer; therefore, only a modified Schottky junction is formed by the diffusion of boron atoms from the PtSi film during the annealing. The junction depth may be as shallow as 30 nm from the PtSi/Si interface. A complete p+n junction is formed for the ITM samples with implantation at 40 keV as well as all the samples implanted at 80 keV. The junction thus obtained has a forward ideality factor lower than 1.02 and a reverse current density less than 0.2 nA/cm2 at -5 V. Activation energy measurement indicates that most of the implantation damages have been recovered after annealing at a temperature as low as 700-degrees-C. The reverse area and peripheral leakage current density are separated by measuring diodes of different perimeter/area ratio. For good samples, the reverse peripheral current comes from the surface generation current within the depletion region underneath the field oxide. All of the experimental results reveal that either Pt or PtSi film can be employed as an efficient barrier film in the ITM/ITS technique to form excellent and ultrashallow junctions with a low thermal budget.
HIGH-TEMPERATURE STABILITY OF PLATINUM SILICIDE ASSOCIATED WITH FLUORINE IMPLANTATION
(1990-04-01)
TSAI, JY
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TSUI, BY
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CHEN, MC
;
交大名義發表
;
電控工程研究所
MULTISTAGE PRE-CANDIDATE SELECTION IN HANDWRITTEN CHINESE CHARACTER-RECOGNITION SYSTEMS
(1994-08-01)
TUNG, CH
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LEE, HJ
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TSAI, JY
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資訊工程學系
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Department of Computer Science
This paper presents a model for reducing the processing time needed for recognition of handwritten Chinese characters via multi-stage pre-candidate selection. The features used in pre-candidate selection are ordered according to the reduction rates evaluated from a set of training characters. A multi-stage pre-candidate selection module is activated for each input character. In each stage, we use a single feature computed from the input character to eliminate impossible categories of characters. When the number of stages increases, the pre-candidate selection time will increase, while the candidate selection time will decrease. The total execution time will decrease when the increase in pre-candidate selection time is less than the decrease in candidate selection time. The total execution time can be predicted from the set of training characters. The number of stages of the pre-candidate selection module is selected to be that which results in the minimum total execution time. Experiments are performed on the CCL/HCCR1 database with 5401 categories of handwritten Chinese characters. The experimental results show that the proposed model can reduce the total execution time significantly without decreasing the precision of the candidate selection module.
NEW PHYSICAL FORMULATION OF THE THERMIONIC EMISSION CURRENT AT THE HETEROJUNCTION INTERFACE
(1993-07-01)
CHANG, KM
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TSAI, JY
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CHANG, 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
The thermionic emission current for electrons across the heterointerface is classically modeled as the difference between two opposing electron fluxes. Here we have developed a new consistent physical model, which includes the carrier degeneracy and nonideal behavior effects, for thermionic emission current at the heterojunction interface. It is shown that the thermionic emission current at the heterojunction interface can be expressed in a simple closed-form formalism which gives the relations among the average directional thermal velocity of electrons, the conduction band discontinuity, and the carrier activities at both sides of the interface. We also discuss the conditions under which the thermionic emission occurs at the heterointerface.