Insight into the physical mechanism of AlxGa1-xN electron blocking layer in GaN-based light emitting diodes

The effect of AlxGa1-xN electron blocking layer (EBL) on suppressing electron leakage from the multiple quantum wells (MQWs) active region has been systematically investigated by conducting the first-principles calculations. Our results revealed that the Al concentration in EBL plays a dominant role in modulating the band offsets of AlxGa1-xN/GaN(0001) (0 < x <= 1) heterointerfaces. The existence of charge accumulation and band bending at these heterointerfaces can be attributed to the strong polarization electric field with the order of MV/cm. We further demonstrated that the EBL can suppress electron leakage from the active region as well as prevent the hole injection from the p-GaN region. Lastly, to boost the quantum efficiency of light-emitting diodes (LEDs), we proposed a "synergistic effect" of Al concentration in EBL and In-content in MQWs. These results provided a fundamental insight into the physical mechanism of the AlxGa1-xN EBL to reduce the efficiency droop in GaN-based LEDs. (c) 2018 Author(s).