Suppressing efficiency droop using graded AlGaN/InGaN superlattice electron blocking layer for InGaN-based light-emitting diodes

In this study, the numerical simulations with graded p-AlxGa1-xN/InyGa1-yN shortperiod superlattice (SPS) electron blocking layer (EBL) of blue InGaN/GaN light-emitting diodes (LEDs) have been investigated by the Advance Physical Model of Semiconductor Devices (APSYS) program. The simulation results show that the LEDs with graded p-AlxGa1-xN/InyGa1-yN SPS EBL exhibit better performances of internal quantum efficiency (IQE) and efficiency droop than those of conventional p-AlGaN/GaN SPS EBL. This is attributed to higher and lower effective potential barrier heights created in the conduction and valence band for electron and hole, respectively. The electron overflow effect can be effectively suppressed and the hole injection ability can also be remarkably enhanced. Therefore, the simulation results exhibit a significant increment in the IQE and the ratio of efficiency droop of the LEDs can be obviously reduced from 17.2% to 4.7%.