Browsing by Author "Lu, Chun-Yi"

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Optical joint density of states in InGaN/GaN-based multiple-quantum-well light-emitting diodes
(2011-11-15)
Wang, Yu-Shou
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Chen, Nai-Chuan
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Lu, Chun-Yi
;
Chen, Jenn-Fang
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電子物理學系
The optical joint densities of states of three InGaN/GaN-based light-emitting diodes with different emission wavelengths (violet, blue and green) operated at various currents were investigated. The results indicate that the blueshift of the emission with increasing current is related to the variation in optical joint density of states. Thus, the blueshift is ascribed to the screening of the piezoelectric field by carriers. A tail at the low-energy end of the density of states, corresponding to localized states, was found, and the presence of these tails broadens the spectra of the devices. (C) 2011 Elsevier B.V. All rights reserved.
Trajectory of a Non-Magnetic Particle Transported by a Rotating Magnetic Particle Chain
(2019-02-01)
Lo, Wen-Yuan
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Lu, Chun-Yi
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Lin, Chih-Ru
;
Chen, Ching-Yao
;
機械工程學系
Transportation of microscale subject is important in the MEMS application. In this paper, movement of a non-magnetic particle driven by a chain consisted of several magnetic particles in a rotational field is experimentally manipulated and observed. The results reveal two distinct motion behaviors of the non-magnetic particle depending on its initial position. For an "outer" particle, whose initial position is at the edge of gyration region, the angular movement is most significant at the timing when contacting with the chain. The net rotating angle of an outer particle per contact remains nearly constant regardless of the length of the rotating chain. Nevertheless, interaction with an "inner" particle, whose initial position is well covered by the gyration, would cause the chain drifting, so that its radial distance to the rotational origin varies continuously. As a result, the overall movement of an inner particle follows a spiral-like trajectory with varying radius in each cycle. Based on the experimental measures, a kinematic model is developed, which enables to numerically predict the trajectory of a non-magnetic particle.