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收集所有交通大學研究人員與學生個人或團體所發表之各項學術著作，涵蓋期刊論文、教師專書、學位論文等項。;;Collections of Publications of NCTU Researchers and Students Like Journal Papers and Thesis.

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Access type: Metadata onlyAuthor: search.filters.author.TSAI, KL

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Now showing 1 - 10 of 11
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    INFLUENCE OF THIN PROTECTIVE INAS LAYERS ON THE OPTICAL-QUALITY OF ALGAAS AND QUANTUM-WELLS
    (1992-09-15)
    TSAI, KL
    ;
    CHANG, KH
    ;
    LEE, CP
    ;
    HUANG, KF
    ;
    CHANG, Y
    Influence of a thin protective but subsequently evaporated InAs layer on the regrowth of AlGaAs has been studied. It was found tha although most of the InAs could be evaporated by thermal desorption, some would react with Al0.36Ga0.64As to form InAlGaAs. These InAlGaAs islands act as potential wells for carrier recombination and dominate the photoluminescence spectrum. Transmission electron microscopy photographs show that dislocations are formed near the islands. These defects are caused by lattice mismatch between AlGaAs and InAlGaAs. These islands and defects strongly affect the optical quality of surrounding Al0.36Ga0.64As and quantum wells.
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    TRANSIENT ANALYSIS OF AN ASYMMETRIC ROTOR-BEARING SYSTEM DURING ACCELERATION
    (1992-11-01)
    LEE, AC
    ;
    KANG, Y
    ;
    TSAI, KL
    ;
    HSIAO, KM
    ;
    交大名義發表
    This paper deals with the transient vibration of asymmetric rotor systems during acceleration passing through several critical speeds at which synchronous or super-harmonic resonance occurs. The dynamic equations of the rotor-bearing system are formulated by the finite element model and the resulting dynamic equations are time-varying due to the effects of acceleration and asymmetry. In the formulation, a Timoshenko beam element is employed to simulate the rotating shaft and Eulerian angles are used to describe the orientations of the shaft element and disk. The numerical integration scheme for transient analysis is generated from the finite element model. Numerical examples are presented to illustrate (1) the effects of acceleration on peak amplitude and speed at which the peak occurs as the system passes through critical speeds, (2) the optimal acceleration process, which can be obtained by minimizing the peak response and the period of acceleration, (3) the speed regions where the transient instability exists.
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    NOVEL ALGAAS/GAAS HETEROJUNCTION BIPOLAR-TRANSISTORS FABRICATED BY 2-STAGE MOLECULAR-BEAM EPITAXY
    (1993-04-01)
    CHEN, HR
    ;
    CHANG, CY
    ;
    TSAI, KL
    ;
    TSANG, JS
    ;
    LEE, CP
    Two-stage molecular beam epitaxy (MBE) growth was employed to fabricate AlGaAs/GaAs heterojunction bipolar transistors (HBTs) for the first time. Due to the unique base contact layer design, the base can be made very thin without increasing the extrinsic base sheet resistance and the etching of the base contact can be done very easily and very reliably. In addition, the base-collector separation layer design contributed to the reduction of parasitic capacitance. D.C. differential current gains up to 110 and 200 were obtained for 1000 and 500 angstrom base width, respectively.
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    FUNDAMENTAL MODE-OPERATION OF HIGH-POWER INGAAS/GAAS/ALGAAS LASER ARRAYS
    (1993-05-01)
    TSANG, JS
    ;
    LIOU, DC
    ;
    TSAI, KL
    ;
    CHEN, HR
    ;
    TSAI, CM
    A new ridge waveguide laser array with stable fundamental mode operation has been fabricated. By introducing absorption regions in all the laser stripes except for the central one, the electric field distribution of the laser arrays and the modal gains of the array supermodes are changed, resulting in fundamental mode operation. The threshold current of an array with five elements is typically 40 mA and the maximum output power is higher than 150 mW. The single-lobed far-field pattern centered at 0-degrees with full width at half maximum of 2-degrees is obtained at 1.5 times of the threshold current (I(th)).
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    2-COLOR INFRARED PHOTODETECTOR USING GAAS/ALGAAS AND STRAINED INGAAS/ALGAAS MULTIQUANTUM WELLS
    (1993-06-28)
    TSAI, KL
    ;
    CHANG, KH
    ;
    LEE, CP
    ;
    HUANG, KF
    ;
    TSANG, JS
    A two-color infrared detector using GaAs/A]GaAs and strained InGaAs/AlGaAs multiquantum wells is demonstrated. The response peak of the GaAs/AlGaAs quantum well is at 8 mum, and that of the InGaAs/AlGaAs quantum well is at 5.3 mum. The responsivity of the detector is 1 A/W at 8 mum and 0.27 A/W at 5.3 mum; these are the best values reported for a two-color quantum well infrared detectors (QWIPs) with peak sensitivities in the spectral regions of 3-5.3 mum and 7.5-14 mum. Single-colored 5.3 and 8 mum QWIPs were also fabricated to study the bias dependent behavior. This behavior can be explained using the concept of current continuity. Because of a higher electrical resistance, a high electric field domain is always formed first in the shorter wavelength quantum well stack.
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    THE STUDY OF EMITTER THICKNESS EFFECT ON THE HETEROSTRUCTURE EMITTER BIPOLAR-TRANSISTORS
    (1993-07-15)
    CHEN, HR
    ;
    LEE, CP
    ;
    CHANG, CY
    ;
    TSANG, JS
    ;
    TSAI, KL
    AlGaAs/GaAs heterostructure emitter bipolar transistors were grown with emitter thicknesses varied from 300 to 900 angstrom and the emitter thickness effects on the current gain and offset voltage were studied. It was found that both the current gain and offset voltage are strongly dependent on the emitter thickness. The current gain decreases with increasing emitter thickness. For an emitter thickness smaller than 500 angstrom, the offset voltage decreases with increasing emitter thickness, but for an emitter thickness larger than 500 angstrom, the offset voltage stays at a nearly constant value. Offset voltage as low as 55 mV was obtained for an emitter thickness of 700 angstrom. This low offset voltage, mostly contributed by the geometric effect, indicates that the base-emitter junction is a homojunction. From the current gain and offset voltage considerations, the optimal emitter thickness was found to be about 300-500 angstrom.
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    EVIDENCE OF ZERO POTENTIAL SPIKE ENERGY IN ALGAAS GAAS HETEROSTRUCTURE EMITTER BIPOLAR-TRANSISTORS
    (1993-10-01)
    CHEN, HR
    ;
    LEE, CP
    ;
    CHANG, CY
    ;
    TSAI, KL
    ;
    TSANG, JS
    The potential spike energy at the emitter junction of AlGaAs/GaAs heterostructure emitter bipolar transistors (HEBT) was directly measured for the first time. Experimental data revealed that emitter thickness as thin as 300 angstrom is thick enough to eliminate potential spike without compositional grading. It is found that the band bending in n-GaAs reduces the potential spike and hence very low offset voltage of 70 mV with high current gain of 150 can be obtained.
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    INVESTIGATION OF INDIUM DOPING IN INGAAS GAAS ALGAAS GRADED-INDEX SEPARATED CONFINEMENT HETEROSTRUCTURE LASERS
    (1993-10-15)
    TSANG, JS
    ;
    LEE, CP
    ;
    LIU, DC
    ;
    CHEN, HR
    ;
    TSAI, KL
    The effect of indium doping in the graded-index regions of the InGaAs/GaAs/AlGaAs graded-index separated confinement heterostructure quantum well laser has been studied. It was found that the threshold current density can be greatly reduced by a proper amount of In doping in the graded AlGaAs region. This result is attributed to an improvement in material quality due to a reduction in group III vacancies. The effect of thermal treatment on laser performance has also been studied. Although high temperature annealing can significantly improve non-In-doped lasers, it has little effect on In-doped lasers.
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    ASYMMETRIC DARK CURRENT IN QUANTUM-WELL INFRARED PHOTODETECTORS
    (1994-05-02)
    TSAI, KL
    ;
    LEE, CP
    ;
    CHANG, KH
    ;
    LIU, DC
    ;
    CHEN, HR
    Asymmetric dark current versus voltage characteristics in quantum weil infrared photodetectors have been studied. A model based on asymmetrical potential barriers was proposed. The asymmetrical potential barriers, which are most likely due to the accumulation of oxygen impurities at one of the interfaces, cause the asymmetrical I-V characteristics. The height of the potential spike is found to increase with the Al content in the AlGaAs barriers. Calculations based on our model agree well with experimental results.
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    INFLUENCE OF OXYGEN ON THE PERFORMANCE OF GAAS/ALGAAS QUANTUM-WELL INFRARED PHOTODETECTORS
    (1994-07-01)
    TSAI, KL
    ;
    LEE, CP
    ;
    CHANG, KH
    ;
    CHEN, HR
    ;
    TSANG, JS
    The influence of oxygen on the performance of GaAs/AlGaAs quantum well infrared photodetectors (QWIP) has been studied. Photoluminescence and secondary ion mass spectroscopy were used to examine the relationship between the quality of AlGaAs and the oxygen content that were then correlated to the performance of QWIPs. It was found that oxygen is the dominant impurity in the GaAs/AlGaAs superlattice. Because oxygen atoms behave likes electron traps, which effectively reduce the carrier concentration in the material, both of the responsivity and the dark current of QWIP are reduced. The detectivities of QWIPs with lower oxygen concentrations are better than those with higher oxygen concentrations.