Comparative Study on Temperature‐Dependent Internal Quantum Efficiency and Light–Extraction Efficiency in III‐Nitride–, III‐Phosphide–, and III‐Arsenide–based Light‐Emitting Diodes

This study attempts to understand and elucidate the factors limiting/determining the external quantum efficiency (EQE) of light‐emitting diodes (LEDs) depending on material systems, i.e., III‐arsenide (GaAs), III‐phosphide (AlGaInP), and III‐nitride (GaInN), via the temperature measurements (30–500 K). The behaviors of EQEs are investigated carefully in terms of the thermal droop and efficiency droop, revealing that the thermal droop in the AlGaInP and GaAs LEDs, while the efficiency droop in the GaInN LEDs, is a critical factor limiting the EQE. To deepen the insight, the EQE is separated into internal quantum efficiency (IQE) and light‐extraction efficiency (LEE). Further, the IQE is separated into radiative efficiency (RE) and injection efficiency (IE). The analysis shows that the LEE plays a significant role in the thermal droop for the AlGaInP and GaAs LEDs. Meanwhile, the IE and RE play a significant role in the EQE reduction of the blue and red LEDs at high temperatures and high current injection.