测量了GaN基紫光LED的光功率(P)在不同工作电流和环境温度(室温和60℃)下随时间的变化,研究了LED的可靠性.结果表明,紫光LED的功率在前48h内迅速衰减,而在48h后衰减速率减慢;与光功率的衰减规律相对应,其I-V曲线的变化显示反向漏电流和正向小电压下的电流都有明显的增加.对载流子的输运机制的分析表明,在LED的工作过程中,缺陷提供的辅助电流通道使载流子的辐射复合几率降低,LED光功率下降.
Optical power of violet light emitting diodes were measured during DC aging test up to 312 h at different current levels (20 and 40 mA), and different ambient temperatures (room temperature and 60 ℃). It was found that violet LED optical power decreased drasmaticaly with aging time within 48 h and slowly after 48 h. Analyzing the I-V curve of virgin violet LED and aged ones, tunneling current is the main component of reverse current and forward current at low bias. It is believed that tunneling current increases mainly because large amount of defects, which provides opportunity of electron tunneling from n-GaN to p-GaN involving unradiative recombination processes.