Epitaxial Structure Optimization for High Brightness InGaN Light Emitting Diodes by Using a Self-consistent Finite Element Method

Abstract

The epitaxial layer structures for blue InGaN light emitting diodes have been optimized for high brightness applications with the output power levels exceeding 1000 W/cm 2 by using a self-consistent finite element method. The light-current-voltage relationship has been directly estimated from the multiband Hamiltonian for wurtzite crystals. To analyze the efficiency droop at high injection levels, the major nonradiative recombination processes and carrier spillover have also been taken into account. The wall-plug efficiency at high injection levels up to several thousand A/cm 2 has been successfully evaluated for various epilayer structures facilitating optimization of the epitaxial structures for desired output power levels.

Numerical Study of Enhanced Performance in InGaN Light-Emitting Diodes with Graded-composition AlGaInN Barriers

“…This well-known phenomenon is referred to as efficiency droop. Over the past years, several different suggestions regarding the mechanism of efficiency droop have been reported, including carrier leakage out of the multi-quantum well (MQW) active region [9,10], Auger nonradiative recombination [11], junction heating [12], the dislocation density [13], non-uniform distribution of holes [14], polarization fields [15] and the quantum-confined Stark effect (QCSE) [16]. Nevertheless, the major origin of the efficiency droop behavior is still not completely understood.…”