GaN基白光LED电极的失效机制

Failure Mechanism Analysis of Negative Electrode in GaN-based White LED

对负电极脱落造成白光LED失效进行了研究。结合扫描电子显微镜(SEM)和能谱分析(EDS)对退化样品芯片进行了表面形貌表征和微区成分分析。SEM观察到退化样品负极脱落处表面粗糙不平,且透明导电薄膜存在颗粒状结晶。经EDS检测发现负极脱落处存在腐蚀性氯元素,并在封装胶中检测出氯。分析认为,封装胶中残留的氯离子与负极中Al层发生的电化学腐蚀是致使样品失效的主要原因。

The failure mechanism of white LED negative electrode shedding phenomenon was investigated. Scanning electron microscopy（ SEM） and energy dispersive spectroscopy（ EDS） were used as two main techniques to characterize the surface morphology and composition of the chip. SEM shows that the surface of negative electrode dropped off is coarse,and granular crystals are formed in the transparent conductive film. Chlorine element has been detected in both corroded negative electrode part and the packaging glue by EDS testing. It is found that the electrochemical corrosion between chloridion and aluminum is the main reason to result in LED failure.