Current-induced degradation of high performance deep ultraviolet light emitting diodes

Abstract

Lifetime measurements on single-chip, packaged 285 nm light-emitting diodes (LEDs) performed under constant current injection at 20 and 75 mA, were compared to the performance of unbiased LEDs baked at the equivalent operating junction temperatures. The thermally stressed devices showed a lesser degradation than those electrically stressed, indicating that elevated temperature alone does not cause degradation. Despite a decay to less than half of the initial power under current injection, time-resolved photoluminescence of the active region exhibits little change, while capacitance-voltage measurements imply that the reduced efficiency and power decay originate from the generation of point defects near the p-side of the p-n junction.