Highly efficient InGaN green mini-size flip-chip light-emitting diodes with AlGaN insertion layer

Abstract

We demonstrate highly efficient InGaN-based mini-size green light-emitting diodes (mLEDs) with AlGaN insertion layer in InGaN/GaN multiple quantum wells (MQWs) using metal organic chemical vapor deposition (MOCVD). High resolution transmission electron microscopy (HRTEM) results reveal that ‘V’ defects within active region can be effectively reduced by AlGaN insertion layer. Photoluminescence (PL) and time resolved photoluminescence (TRPL) results indicate an increase of radiative recombination efficiency. Very high performance 523 nm InGaN green flip-chip mLEDs (0.025 mm2) with distributed Bragg reflector (DBR) show a high external quantum efficiency (EQE) of 38.0%, a high wall-plug efficiency (WPE) of 32.1% and a low forward voltage of 2.8 V at a working current density of 20 A cm−2, which are very promising for display application.