Low-frequency noise in as-fabricated and degraded blue InGaAs/GaN LEDs

Study of the spectral noise density and its dependence on current density in as-fabricated and degraded blue light-emitting diodes (LEDs) based on InGaN/GaN quantum-well structures are reported. It is shown that defects are generated nonuniformly in the course of degradation, being concentrated along extended defects penetrating into the active region of LEDs. It is demonstrated that the decrease in the external quantum efficiency in the course of aging is due to the enhancement of charge transport uniformity, which leads to the formation of shunts and local overheating regions. Typically, in blue LEDs, these effects are responsible for the ambiguous development of the degradation process, which hinders prognostication of LED service life. The effect of noise suppression is observed in a narrow current density range (10$^{-2}$ to 10$^{-1}$ A cm10$^{-2}$) corresponding to the onset of radiative recombination.