Numerically Investigate Al _0.78 Ga _0.22 N/Al _0.72 Ga _0.28 N/Al _0.78 Ga _0.22 N p‐Electron Blocking Layer to Manipulate the Carrier Transport for AlGaN‐based Deep‐Ultraviolet Fabry–Pérot Laser Diodes

Due to high ionization energy of Mg impurity and low hole mobility, AlGaN‐based deep‐ultraviolet Fabry–Pérot laser diodes suffer from poor hole injection efficiency and thus low laser power. Here, we design an Al _0.78 Ga _0.22 N (L1)/Al _0.72 Ga _0.28 N (L2)/Al _0.78 Ga _0.22 N (L3) p‐type electron blocking layer (p‐EBL) structure. We find that the proposed p‐EBL affects both thermionic emission and intraband tunneling for holes. Our studies indicate that thin layer L3 favors the hole injection into the layer L2. The very strong polarization‐induced electric field causes hole accumulation at the L1/L2 interface. The other advantage for such a design is that the layer L2 can spatially separate the injection holes and leakage electrons. This will suppress the recombination between holes with leakage electrons in the bulk p‐type region, which further increases the local hole concentration at the L1/L2 interface and helps reduce the valence band barrier height of the layer L1. As a result, the thermionic emission for holes can be enhanced, leading to the enhanced laser power. The simultaneously reduced electron leakage level also suppresses the roll‐over of the laser power for the proposed device. Moreover, if the carrier injection and optical loss are balanced, the performance can be further improved.