Current- and temperature-dependent efficiency droops in InGaN-based blue and AlGaInP-based red light-emitting diodes

Abstract

We investigate the current-dependent and temperature-dependent efficiency droops ("J-droop" and "T-droop", respectively) in InGaN-based blue and AlGaInP-based red light-emitting diodes (LEDs). It is found that the blue and red LEDs show different droop behaviors with increasing current density and temperature. The J-droop is significant in the blue LED while the T-droop is severe in the red LED. In case of the blue LED, the carrier accumulation caused by the saturation of the radiative recombination rate is thought to increase the quasi-Fermi level rapidly, thus causing the J-droop. On the other hand, the T-droop of the red LED is influenced by redistribution of carriers due to the increased thermal energy with a small barrier height in the AlGaInP material system. The comparison of different droop characteristics of blue and red LEDs helps understand the recombination mechanisms of both LEDs and provides useful insight for improving the device performance further. (C) 2019 The Japan Society of Applied Physics.