Performance characteristics of InAlGaN laser diodes depending on electron blocking layer and waveguiding layer design grown by metalorganic chemical vapordeposition

We report the effects of epitaxial layer design on III-N visible laser diode (LD) performance. In order to mitigate electron accumulation at the interface between the top GaN quantum barrier and the AlGaN electron blocking layer (EBL) induced by polarization fields, a tapered AlGaN EBL was used. Compared to LDs with conventional AlGaN EBLs, the threshold current density of LDs with a tapered AlGaN EBL is significantly reduced and the slope efficiency is increased. In0.03Ga0.97N was used as waveguide layers in blue LD structures to increase the optical confinement. It is observed that In0.03Ga0.97N waveguiding layers significantly improve the emission efficiency of the active region in addition to offering better optical confinement. The responsible underlying mechanism has been investigated.