Comprehensive study of current-density-dependent degradation in AlGaInP/GaInP based red micro-LEDs

초록

The reliability degradation behavior of 20-& micro;m AlGaInP/GaInP red micro-LEDs under electrical stress was systematically investigated as a function of current density. Devices operated at 750 A/cm2 exhibited a degradation rate more than twice that observed at 250 A/cm2, together with markedly enhanced spectral broadening and chromaticity variation, revealing pronounced optical instability at high injection levels. Quantitative analysis of recombination kinetics showed a significant increase in the Shockley-Read-Hall (SRH) coefficient A, associated with defect-assisted recombination, accompanied by a slight decrease in the radiative recombination coefficient B, while the Auger-related coefficient C remained nearly invariant. Electroluminescence mapping further demonstrated that degradation is spatially concentrated near the device sidewalls under high-current operation, directly linking the observed color variation to intensified surface-dominated nonradiative recombination. These findings highlight the critical role of sidewall-related defect activation under high-current operation. Consequently, the operating current region for red micro-LEDs should be defined by jointly considering lifetime degradation and color stability, establishing an application-specific reliability strategy that balances optical uniformity and long-term device stability.

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