Criteria of unpredictable failure for high-power InGaN LEDs

The results of the degradation study of commercial InGaN/GaN LEDs with the external quantum efficiency (EQE) ∼ 40–50 % at 450–460 nm are presented. It has been clarified that one of the mechanisms responsible for EQE degradation and the unpredictable failure of LEDs is the multiphonon recombination of carriers. The distorted forward branch of I-V characteristics at U < 2V and the appearance of the SI ∼j4 section on the current spectral noise density dependences on current density in LEDs before or after 100 hours of aging test are the criteria identifying an unpredictable failure.