Browsing by Author "Chan, C. H."

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Carrier Dynamics and Dynamic Band-Bending in Type-II ZnTe/ZnSe Quantum Dots
(2013-11-01)
Syperek, M.
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Misiewicz, J.
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Chan, C. H.
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Dumcenco, D. O.
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Huang, Y. S.
Carrier dynamics and dynamic band-bending in self-assembled ZnTe/ZnSe quantum dots have been studied by means of time-resolved photoluminescence experiment at low temperatures. The experiment reveals clearly type-II character of the confinement potential in the dot manifested in: (i) long photoluminescence decay time constant of 28-35 ns, and (ii) temporal shift of the quantum dot peak emission towards low energy following the laser pulse excitation. The magnitude of the spectral shift Delta E depends on the dot size and the power density of excitation pulse. For the dots under study and given experimental conditions Delta E approximate to 28 divided by 42 meV.
The Study of a Dual-Disk Type Piezoelectric Actuator
(2013)
Chen, W. M.
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Chan, C. H.
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Liu, T. S.
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機械工程學系
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Department of Mechanical Engineering
This study presents an innovative piezoelectric actuator, capable of long travel distance and fast speed. Main components of the actuator include a rod and two piezoelectric buzzers of disk geometry. Being subject to the piezoelectric force and Coulomb friction, the piezoelectric actuator can move rapidly. Equations of motion are derived based on piezoelectric properties and Newton's law. Static and kinetic friction effects are incorporated. Stress and strain calculations and piezoelectric equations are included in derivation. Circular plate models with polar coordinates are used to account for piezoelectric properties of buzzers. Experimental results are compared with theoretical results. According to experimental results, the present actuator can move at the speed of 37.5 mm/sec and generate the force of 15.4 mN.