Browsing by Author "Lin, C. A."

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n-ZnO/LaAlO3/p-Si heterojunction for visible-blind UV detection
(2012-03-15)
Tasi, D. S.
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Kang, C. F.
;
Wang, H. H.
;
Lin, C. A.
;
Ke, J. J.
A visible-blind UV photodetector (PD) using a double heterojunction of n-ZnO/LaAlO3 (LAO)/p-Si was demonstrated. Inserted LAO layers exhibit electrical insulating properties and serve as blocking layers for photoexcited electrons from p-Si to n-ZnO, leading to an enhanced rectification ratio and a visible-blind UV detectivity of the n-ZnO/LAO/p-Si PDs due to the high potential barrier between LAO and p-Si layers (similar to 2.0 eV). These results support the use of n-ZnO/LAO/p-Si PDs in the visible-blind UV PDs in a visible-light environment. (C) 2012 Optical Society of America
Photoinduced fluorescence enhancement in colloidal CdSeTe/ZnS core/shell quantum dots
(2008-05-05)
Yuan, C. T.
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Chou, W. C.
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Chuu, D. S.
;
Chen, Y. N.
;
Lin, C. A.
Photoinduced fluorescence enhancement (PFE) in colloidal CdSeTe/ZnS core/shell quantum dots (QDs) was investigated by monitoring ensemble fluorescence and single-QD fluorescence blinking behavior upon illumination. Ensemble fluorescence was increased in air and in vacuum with different enhanced factors. At the single-QD levels, fluorescence was also enhanced for some individual QDs. Relatively long on times, high quantum yields within the on times, and multilevel on states were found in fluorescence time traces. We suggest that the PFE origin from single-QD viewpoint is attributed to the contributions of surface passivation by photoinduced charged carriers and the formation of neutral core/charged shell QD states. (C) 2008 American Institute of Physics.
Single fluorescent gold nanoclusters
(2009-08-31)
Yuan, C. T.
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Chou, W. C.
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Tang, J.
;
Lin, C. A.
;
Chang, W. H.
Both ensemble and single-molecule measurements were performed to explore the fluorescence properties of Au nanoclusters (NCs). Photoinduced fluorescence enhancement was observed for ensemble NCs in solution, but photobleaching was found at ambient environments. At the single-molecule level, fluorescence blinking and single-step photobleaching were observed. Furthermore, their time-resolved fluorescence shows a single exponential decay with a lifetime of similar to 7 ns and is insensitive to changes in fluorescence intensity. The lifetime distribution is more homogeneous within ensemble Au NCs as compared to CdSe QDs. Therefore, Au NCs have potential applications as nontoxic fluorescent labels for lifetime-based imaging microscopy. However, their low quantum yields and poor photostability are disadvantageous factors, which require further improvement. (C) 2009 Optical Society of America