Degradation behaviors of high power GaN-based blue light emitting diodes

Abstract

The degradation mechanism of high power InGaN/GaN blue light emitting diodes (LEDs) is investigated in this paper. The LED samples were stressed at room temperature under 350-mA injection current for about 400 h. The light output power of the LEDs decreased by 35% during the first 100 h and then remained almost unchanged, and the reverse current at −5 V increased from 10 −9 A to 10 −7 A during the aging process. The power law, whose meaning was re-illustrated by the improved rate equation, was used to analyze the light output power-injection current (L-I) curves. The analysis results indicate that nonradiative recombination, Auger recombination, and the third-order term of carriers overflow increase during the aging process, all of which may be important reasons for the degradation of LEDs. Besides, simulating L-I curves with the improved rate equation reveal that higher-than-third-order terms of carriers overflow may not be the main degradation mechanism, because they change slightly when the LED is stressed.

Effects of High‐g Impact on Physical, Electrical, and Optical Characteristics of Light‐Emitting Diodes

“…The exact mechanism for the change in properties is not clear, but there are some similarities with past LED degradation studies. In these studies, with conditions 150 A/cm 2 forward current stress or À20 V reverse bias stress up to 120 h, forward voltage decreases as stress time increase (13,14). Trends in reverse current with stress are also observed; they are not fully understood yet but are attributed to defect growth and annealing processes (15).…”

A Technique for Improving the Precision of the Direct Measurement of Junction Temperature in Power Light-Emitting Diodes

“…Despite the efficiency and the long-term durability claimed by LED manufacturers, high power LEDs still suffer from excessive heating, which affects their luminous flux and operating lifetime [6][7][8][9]. Proper heat dissipation systems, whether active or passive, can mitigate these side effects, but impose higher costs and more performing form factors of the lamp housing [10,11].…”

Enhanced performance of photonic crystal GaN light-emitting diodes with graphene transparent electrodes

“…Finally, the single-layer graphene grown by CVD was transferred to the surface of the LED for two times, to form the transparent electrodes. The Ni/Au thin layer was inserted between the graphene and the p-GaN to get a better ohmic contact [24][25][26]. The sheet resistances of the mono-and two-layer graphene are about~600 Ω/□ and~300 Ω/□, respectively.…”