Browsing by Author "LEE, YS"

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AMBIPOLAR PERFORMANCES OF NOVEL AMORPHOUS SILICON-GERMANIUM ALLOY THIN-FILM TRANSISTORS
(1993-08-01)
HSIEH, SW
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CHANG, CY
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LEE, YS
;
LIN, CW
;
WU, BS
The limitation of low hole mobility in hydrogenated amorphous silicon thin-film transistors (a-Si:H TFTs) was overcome in this present work by utilizing hydrogenated amorphous silicon-germanium (a-Si1-xGex:H) alloys as the active channel of TFTs. The performance of hydrogenated amorphous silicon-germanium thin film transistors (a-SiGe:H TFTs) was optimized by switching the germane-to-silane flow ratio. The fabricated a-SiGe:H TFT with 12 at% germanium content was measured as possessing an electron mobility of 0.71 cm2/V.s and a hole mobility of 0.54 cm2/V.s. The on/off current ratio ranging over almost six orders of magnitude in both conduction modes was obtained. Thus a-SiGe:H TFT has offered the opportunity for upgrading of a-Si:H TFTs and would be feasible for application in [CMOS] circuits.
ELECTRICAL-PROPERTIES OF MULTILAYER-CHIP ZNO VARISTORS IN A MOIST-AIR ENVIRONMENT
(1994-11-01)
YEN, AJ
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LEE, YS
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TSENG, TY
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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
Multilayer-chip varistors mere prepared using the ZnO-glass system by applying tape casting technology. The effect of processing conditions on the multilayer ceramic microstructure and electrical properties mas studied. The location, size, and density of the pores within the multilayer structure were examined by scanning electron microscopy and the displacement method using distilled mater. The experimental results showed that the electrical properties of a multilayer-chip varistor could be influenced substantially by the porosities associated with environmental moisture in the range approximate to 15%-95% relative humidity at 25 degrees C. Such an effect can cause substantial current leakage as well as the separation of the I-V curves into four regions, i.e., prebreakdown, linear, breakdown, and upturn. A proposed pore model and equivalent circuit for the multilayer-chip ZnO varistors have been simulated with a commercial varistor and a serial resistance to demonstrate the observed I-V phenomena.
INFLUENCE OF PROCESSING PARAMETERS ON THE MICROSTRUCTURE AND ELECTRICAL-PROPERTIES OF MULTILAYER-CHIP ZNO VARISTORS
(1995-04-01)
LEE, YS
;
TSENG, TY
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Multilayer-chip varistors based on ZnO with lead zinc borosilicate glass instead of Bi2O3 were prepared by tape casting and green-sheet lamination processes using a non-aqueous slurry system. The influences of slurry composition and the degassing process on the microstructure and non-ohmic properties of multilayer-chip varistors were studied. The electrical properties of chip varistors can be influenced substantially by the pore defects resulting from an unsuitable slurry formulation for the tape-casting process. The sintering temperature of the chip varistors was lowered to 1100 degrees C and silver-palladium alloys were employed as internal electrodes. The non-linear coefficients of 27-32 and breakdown voltages of 7.6-24.5 V were achieved by controlling the green-sheet thickness and sintering temperatures in the present study. The Delta V-br/V-br values for the chip varistors lie within +/-10%, indicating excellent surge-withstanding capability.
OBJECT MOVEMENT IN DISTRIBUTED OBJECT-ORIENTED SYSTEMS
(1994-05-01)
LEE, YS
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WANG, FJ
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CHANG, CH
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交大名義發表
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資訊科學與工程研究所
In a distributed object-oriented system-a system containing more than one object-oriented system (OOS)-different OOSs may contain classes with different definitions, different definitions but the same name, or the same definition but different names. Moving an object between two OOSs includes locating a suitable class and creating an instance of the class with the value of the moved object in the destination system. This study discusses what is a suitable class for a moved object in the destination OOS and presents the algorithms for finding such a suitable class. It also discusses the activities of copying the value of the moved object into the instance of a located class in the destination site. A general object movement mechanism and its implementation for a domain specific model are then incorporated into a prototype of a distributed OOS, called DOOSPE.
PHASE IDENTIFICATION AND ELECTRICAL-PROPERTIES IN ZNO-GLASS VARISTORS
(1992-06-01)
LEE, YS
;
TSENG, TY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Ceramic varistors based on ZnO with lead zinc borosilicate glass instead of Bi2O3 Were prepared. The effect of sintering conditions on the electrical properties was studied by sintering samples at various temperatures and cooling them at different rates. The sample sintered at 1250-degrees-C for 1 h, then furnace cooled, possessed the best electrical properties, as characterized by the highest nonlinear coefficient, lowest leakage current, and lowest degradation. The microstructure and crystal structure of the glass phase of ZnO-glass varistors were examined by means of scanning electron microscopy, transmission electron microscopy, and powder X-ray diffractometry. The glass phase was originally amorphous, but crystallized as an intergranular layer in the sintered and furnace-cooled samples. This crystallized phase was a zinc borate phase (5ZnO.2B2O3), which was identified by X-ray diffractometry, transmission electron microscopy, and Auger electron spectroscopy. The zinc borate phase at the grain boundary of ZnO-glass samples enhanced the nonohmic characteristics of the ceramic varistors.
PROPERTIES OF PLASMA-ENHANCED CHEMICAL-VAPOR-DEPOSITED A-SINX-H BY VARIOUS DILUTION GASES
(1994-09-15)
HSIEH, SW
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CHANG, CY
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LEE, YS
;
LIN, CW
;
HSU, SC
The effects of dilution gases on hydrogenated amorphous silicon nitride (a-SiNx:H) films were investigated. Silane and ammonia were used as the reactive species, while nitrogen, helium, hydrogen, and argon were used as the-dilution gases in a plasma-enhanced chemical vapor-deposition system at a substrate temperature of 300 degrees C. The electrical, physical, and chemical properties of the a-SiNx:H films were found to be highly sensitive to the various kinds and flow rates of the carrier gases in the deposition. Additionally, the physical properties of growth rate, refractive index, and etching rate were also investigated. The hydrogen bonding configuration was explored by infrared spectroscopy. The total hydrogen concentrations for all a-SiNx:H films were observed to be smaller than 3.0X 10(22) cm-(3). The electrical properties were characterized by I-V and C-V measurements in metal-insulator-semiconductor structures. The breakdown strength was determined at the current density of 3 mA/cm(2); in addition, the dominant mode of electronic conduction would appear to be the Poole-Frenkel emission. The interface trap state density D-it which ranged from 3.4X10(11) to 1.3X10(12) cm(-2) eV(-1) was evaluated by the C-V characteristics. Finally, the influences of the gas dilution in the alpha-SiNx:H films, as applied to the devices, were investigated by using the hydrogenated amorphous silicon thin-film transistors (a-Si:H TFTs). Analyses of the transfer characteristics of the TFT devices revealed that the density of deep gap states is 4x10(12) cm(-2) eV(-1) and the field-effect mobility mu(FE) is changing from 0.37 to 1.45 cm(2)/V s.