Effect of Carrier Localization and Shockley-Read-Hall Recombination on the Spatial Distribution of Electroluminescence in InGaN LEDs

We investigate divergent behaviors in the emission of blue and green light-emitting diodes (LEDs) when they are subjected to the current-stress aging. Microscopic hyperspectral imaging is introduced to measure spatially resolved mappings of the peak intensity, the peak energy, and the full width at half maximum. Also, plots of external quantum efficiency versus injection current are measured to determine the extent of the Shockley-Read-Hall (SRH) nonradiative recombination rate based on the two-level model. As a result, a phenomenological model is proposed to account for the competitive mechanism between the carrier localization and the SRH recombination. In the blue LED case, the increase in the radiative recombination within localization states cancels the SRH nonradiative recombination within point defects. While in the green LED case, the enhancement of SRH recombination and the remission of carrier localization jointly kill the radiative recombination.