InGaN-Based Light-Emitting Diodes With an AlGaN Staircase Electron Blocking Layer

In this letter, we investigate the external quantum efficiency (EQE) and efficiency droop characteristics of InGaN-based light-emitting diodes (LEDs) incorporating Al
_x
Ga
_1-x
N staircase electron blocking layers (EBLs). The LED featuring a composition-stepped EBL (x: 0.21, 0.14, and 0.07) exhibited the highest EQE under low current levels, but a severe efficiency droop at high current levels. In contrast, the LED with a composition-stepped EBL (x: 0.07, 0.14, and 0.21) exhibited a significant improvement in its onset of droop and a mitigated efficiency droop; we ascribe these features to the increased hole injection rate and the decreased built-in electric field.