Browsing by Author "Shei, Shih-Chang"

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Degradation of AlGaInP light emitting diodes under reverse-bias operations in salty water vapor
(2015-08-01)
Chen, Hsiang
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Chu, Li-Chen
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Lee, Ming Ling
;
Kang, Nai Chung
;
Shei, Shih-Chang
GaP-based light emitting diodes (LEDs) reliability tests are crucial to further development for high-performance LED lighting technology. In this study, we perform reverse-bias stress tests for LEDs in water vapor and salty water vapor ambient, respectively. The results indicate that salty water vapor can quickly degrade LEDs. To investigate the failure mechanisms, electrical measurements, forward-bias and reverse-bias electroluminescence images, and multiple material analyses have been taken to study the failure mechanism. Results indicate that NaCl clustering solids and atom diffusion may cause deformation of the electrode and enhance the degradation of the LEDs. (c) 2014 Elsevier Ltd. All rights reserved.
Optical and electrical characterization of reverse bias luminescence in InGaN light emitting diodes
(2011)
Chen, Hsiang
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Kao, Chyuan-Haur
;
Lu, Tien-Chang
;
Shei, Shih-Chang
;
光電工程學系
This study investigates the reliability physics of the reverse bias luminescence (RBL) of InGaN/GaN light emitting diodes. Optical and electrical characterization techniques including surface temperature measurements, 2D X-ray fluorescent element analysis, and 2D electroluminescence (EL) measurements reveal the leakage current distribution and the origin of the reverse bias leakage current. Using these techniques, this study examines the electroluminescence behavior and surface temperature distribution in forward bias and reverse bias conditions. Results show that the reverse bias EL originates from hot electron-induced emission, which in turn is due to the leakage current in the high electric field region caused by metal contact abnormalities. The optical and electrical characterization techniques adopted in this study are a promising screening tool for correlating device failures with fabrication processes.