Failure Analysis of a Phosphor-Converted White Light-Emitting Diode due to the CaS:Eu Phosphor

Autor:	Bo Yong Han, Jae Soo Yoo, Jin Hyung Kim, Hyun Ho Shin
Rok vydání:	2008
Předmět:	Materials science Physics and Astronomy (miscellaneous) business.industry General Engineering Analytical chemistry General Physics and Astronomy Gas release Phosphor engineering.material Reflectivity Moisture resistance Coating White light engineering Optoelectronics Particle business Diode
Zdroj:	Japanese Journal of Applied Physics. 47:3524-3526
ISSN:	1347-4065 0021-4922
DOI:	10.1143/jjap.47.3524
Popis:	To improve the longevity of phosphor-converted white light-emitting diode (LED), CaS:Eu red phosphor is usually coated by SiO2. The coating characteristics such as moisture resistance were found to be excellent and critically dependent upon the processing variables such as precursor concentration, pH value, and the temperature of the solution in case of the sol–gel process. Very interestingly, even though SiO2-coated CaS:Eu phosphor shows very strong moisture resistance, longevity of white LED is not improved that much when the coated phosphor applied to LED chip. Our consecutive experimental results show that the CaS:Eu particle is decomposed provoking a H2S gas release and silver pad under the chip is damaged by the H2S gas, which leads to the decrease of reflectivity and consequently luminance from the LED.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::fa65dfb6c59bdfc52bc5ac09ae8c5ce1 https://doi.org/10.1143/jjap.47.3524 Zobrazit plný text záznamu