GaN基LED电流加速失效机理分析

Study on the fabrication and thermal performance of aluminum substrate for high power LED

自行封装了一体化大功率白光GaN基发光二极管(LED),将LED芯片直接封装到铝板上。在室温1A下进行电流加速老化实验,通过对老化前后不同时间段器件的电学、光通量和光谱特性进行测量来分析器件的失效机理,主要分析器件的芯片和荧光粉的失效机理。器件老化前后的电学特性表明,老化过程中,器件的串联电阻和低正向偏压下的热电子发射电流增大;光通量曲线表明,LED所加驱动电压低时,多数载流子的迁移率低,复合效率高,所以在低电流测试下LED的衰减慢;光谱曲线和色温曲线表明,在老化初始阶段,荧光粉的退化很快,一段时间后蓝光芯片衰减占主导。

Accelerated aging tests at 1A were carried out on a new type of integrated high-power white GaN-based light-emitting diodes which we encapsulated the LED chip to the aluminum plate directly.Then the electrical,luminous and spectral characteristics were researched to analyse the failure mechanism of the device including the LED chips and phosphor.The electrical characteristics demonstrated that both the series resistance and thermionic emission current increase after aging.Luminous flux curve shows that the lower electron mobility,the higher the recombination rate,so the decay rate of the LED is slow when the drive current is low.Spectra and color temperature curves show that the phosphor degradated fast in initial stage of aging,well blue chip attenuation was dominant after a certain period of time.