GaN基绿光LED芯片电流加速失效机理研究

采用电流加速的电应力老化方法研究GaN基绿光 LED芯片的失效机理。LED芯片在经过60 mA 电流老化424 h后,其发光效率总体趋势都是随老化时间增加而减小 ,但是小测量电流相比于大测量电 流的发光效率衰减程度更为明显。同时,在正向偏压下电流电压曲线基本没有变化,而反向 偏压下的反向 电流随老化时间的增加而快速增加。笔者认为在电应力老化作用下,随老化时间增加,有源 区的缺陷能级 增多,在正向偏压下,缺陷能级起到一个有效陷阱的作用,增加了载流子的寿命,降低了辐 射复合的几率, 使得发光效率降低,但是并没有减小正向偏压下的电流,而反向偏压时,缺陷能级起到了一 个漏电通道的作用,使得反向电流增大。

Degradation mechanisms of GaN-based green LED after accelerated DC current agin g

The failure mechanism of GaN based green LED chip was studied by elect rical accelerated aging method.After aging for 424h at 60mA current,the optical power of LED dec reased with the increasing aging time,but the trend of optical power decay at low measuring current levels is mo re obvious than that at high measuring current levels.The aging stress does not affect the forward-bias ele ctrical characteristics.However,the reverse-bias current increased rapidly with the increasing aging time.The auth or considers that the defect energy level in the active region increases with the aging time.It is believed that th e defect in LED by electrical stress acted as the effective trap in the forward voltage,which increased the lifetime of carriers and reduced the probability of the radiation recombination.When the voltage is reversed,the de fect acted as the channel of leakage current,which increased the reverse current.