Enhanced performance in AlGaN deep-ultraviolet laser diodes without an electron blocking layer by using a thin undoped Al0.8Ga0.2N strip layer structure

AlGaN-based deep ultraviolet laser diodes (DUV LD) often use electron blocking layers (EBL) to prevent electron leakage into the p-type region. However, EBL can also impede the injection of holes into the active region, resulting in a reduction of laser efficiency. To address this issue, we propose using an undoped thin Al_0.8Ga_0.2N strip structure after the last quantum barrier (LQB) instead of the EBL. Our results show that the 1 nm Al_0.8Ga_0.2N strip layer can effectively suppress electron leakage and enhance hole injection by increasing the effective barrier height when compared to conventional laser designs with EBLs. This improved efficiency results in a higher carrier concentration in the active region, higher recombination efficiency in the quantum well, and a significant increase in the output power of the laser.