Performance improvement of GaN-based blue and ultraviolet double quantum well laser diodes by using stepped-doped lower waveguide

Abstract

We have proposed a new stepped-doped lower waveguide (LWG) and systematically investigated its effect on GaN-based blue and ultraviolet laser diodes (LDs) through the simulation software LASTIP. It is found that increasing doping concentration of the LWG is beneficial to decrease the threshold current and raise the output power. Furthermore, when a suitably designed stepped-doped LWG layer replaces the homogeneously heavily doped LWG layer, the performance of the blue and ultraviolet LDs is further improved. It is mainly attributed to the decrease of electron leakage current and the increase of hole injection current. In addition, the stepped-doped LWG improves ultraviolet LDs characteristics more significantly than the blue LDs, which is due to the reduction of the total optical loss.