Efficiency droop contributors in InGaN green light emitting diodes

Abstract

Here, efficiency droop contributors (i.e., inherent Auger–Meitner recombination, polarization-induced effects, thermal effects, and light extraction) in InGaN green light emitting diodes (LEDs) are decoupled and quantified. First, a modified ABC model is developed, and external quantum efficiency measurements are taken under constant and pulsed currents (EQEConstant and EQEPulsed, respectively). The LED internal quantum efficiency with and without thermal effects (IQEConstantABC and IQEPulsedABC, respectively) is extracted using the modified model. Then, using Raman spectroscopy, the LED junction temperature is extracted. Finally, using the optical-electrical model (OEM), the polarization- and temperature-independent LED internal quantum efficiency (IQEOEM) is calculated from the modified ABC model and the extracted junction temperature. By comparing external (EQEConstant) and the three internal quantum efficiencies (IQEConstantABC, IQEPulsedABC, and IQEOEM), the impacts of inherent Auger–Meitner recombination, polarization-induced effects, thermal effects, and light extraction on the efficiency droop are decoupled and quantified. It is found that inherent Auger–Meitner recombination-induced droop is approximately 49% of the total efficiency droop in commercial green LEDs, while polarization-induced effects contribute about 35%, and thermal droop accounts for nearly 16%. These findings suggest, to quash the green gap, it is critical to search for materials and device designs with low inherent Auger–Meitner coefficients and polarization fields, respectively.