Browsing by Author "Lee, C. -S."

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Electron transport mechanisms in individual cobalt-doped ZnO nanorods
(2012-11-01)
Ko, T. Y.
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Tsai, M. -H.
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Lee, C. -S.
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Sun, K. W.
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應用化學系
This study examined carrier transport in single cobalt-doped zinc oxide (Co:ZnO) nanorods in temperatures ranging from 80 to 405 K. Measurements were taken on single nanorods deposited on a Si template, where two- and four-point metallic contacts were previously made using e-beam lithography, dielectrophoresis, and focused ion beam. In both two-and four-point probe measurements, the current-voltage curves were clearly linear and symmetrical with respect to both axes. The electrical measurements were carried out according to three different measuring methods to accurately determine the resistivity of the single Co:ZnO nanorods. The Co-doped nanorods exhibited ferromagnetic behavior at room temperature. The remanence permanent magnet of the nanorods increased with increasing Co concentration, however, this was accompanied by the decrease in electrical resistivity. The transport properties were dominated by the thermal activation of electrons from the Fermi level to the conduction band for a temperature above 140-160 K, and to the impurity band at a lower temperature. The electronic transport of the nanorods was influenced by the surface states when exposed in the air.
Guest Editorial Special Issue on Deep/Reinforcement Learning and Games
(2018-12-01)
Wu, I. -C.
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Lee, C. -S.
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Tian, Y.
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Mueller, M.
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資訊工程學系
Magnetophotoluminescence properties of Co-doped ZnO nanorods
(2009-04-13)
Lin, C. Y.
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Wang, W. H.
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Lee, C. -S.
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Sun, K. W.
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Suen, Y. W.
We present the detailed experimental results of the magnetic and optical properties of cobalt doped ZnO nanorods, especially the temperature and magnetic field dependence of photoluminescence up to 14 T. The Raman measurements indicate that our Co-doped ZnO nanorods have the same lattice constant as crystalline bulk ZnO. Sharp luminescence peaks centered at around 670 nm were observed at low temperature and their intensity decreased with increasing magnetic field. The luminescence peaks were attributed to d-d transitions in the Ligand field from the doped Co ions. We also observed a diamagnetic shift at a temperature of 1.5 K when the magnetic field was scanned from 0 to 14 T. The exciton radius of the Co-doped ZnO nanorods was deduced from the magnetophotoluminescence results.
Simply self-restored ring-based time-division-multiplexed passive optical network
(2008-04-01)
Yeh, C. -H.
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Lee, C. -S.
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Chi, S.
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光電工程學系
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Department of Photonics
A simply self-restored ring-based time-division-multiplexed passive optical network by a clockwise and counterclockwise circulating fiber against the fiber fault in an access system is proposed and experimentally investigated. The proposed optical line terminal and optical network unit modules can be used to prevent and protect the occurrence of fiber failure in the ring-based passive optical networks (PONs). Using the proposed self-healing access network, the ring-based PON can be revived promptly under fiber failure. The protection and restoration time of the access network is measured within 7 ms. In addition, the performance of data traffic in the access network is also discussed. (C) 2008 Optical Society of America.