A Fast Method for Lifetime Estimation of Blue Light-Emitting Diode Chips Based on Nonradiative Recombination Defects

• Published in: IEEE photonics journal 2017-08, Vol.9 (4), p.1-9
• Main Authors: Xu, Lin-Wang, Qian, Ke-Yuan
• Format: Article
• Language: English
• Subjects: Aging; defect density; Density measurement; lifetime estimation; Light emitting diodes; Light-emitting diode (LED) chip; Radiative recombination; Semiconductor device measurement; semiconductor device reliability; Stress
• ISSN: 1943-0655; 1943-0647
• DOI: 10.1109/JPHOT.2017.2703851

This paper proposes a new method for estimating the lifetime of the InGaN/GaN-based light-emitting diode (LED) chip by analysing the density of nonradiative recombination defects. The nonradiative recombination defect is a major factor affecting the performance of LED chips, and the increase in defects eventually leads to the chip failure. Therefore, the growth rate of defects determines the lifetime of the LED chip. A new measurement method of the defect density is introduced. A batch of 1-W blue LED chips is selected to conduct 6000-h accelerated life tests with constant current stresses. And through studying the data of defect densities and light output, it is concluded that compared with light output, the defect density is more sensitive to the current stress, which indicates that the defect density is more advantageous to reflect the performance degradation of the LED chip. In particular, the growth of defects induced by aging stress is found to follow a logarithmic law, then a mathematical model of the defect growth is introduced. And with the model we can obtain the key parameters about the growth rate of defects. Furthermore, we establish the quantitative relationship between the growth rate of defects and aging lifetime. Based on this relationship, the lifetime of the LED chip can be predicted in a more accurate and faster way. The result shows that under the stress condition of our experiments, this new method requires less than 1000-h stress time, and the traditional method requires more than 6000 h.