Impact of an AlGaN thin insertion layer in the p-GaN region on InGaN/GaN vertical-cavity surface-emitting laser diodes

In this work, we propose a p-GaN/p-Al x Ga 1-x N/p-GaN structure in p-type hole injection layer for InGaN/GaN vertical-cavity surface-emitting laser diodes (VCSEL), and this design can efficiently improve the hole injection into the multiple quantum wells (MQWs). In the p-GaN/p-Al x Ga 1-x N/p-GaN structure, the polarization induced charges generated at the heterojunction interface can produce the polarization induced electric field, which can accelerate holes. Meanwhile, the p-Al x Ga 1-x N layer also favors the current transport into the cavity center that can better enhance the device performance, i.e., the threshold current can be reduced and the lasing power can be enhanced. Moreover, we also find that the device performance is sensitive to the structural designs for the p-GaN/p-Al x Ga 1-x N/p-GaN junctions. Thus, the parametric investigations have also been conducted in this work. • The p-Al x Ga 1-x N layer can create the polarization induced electric field and accelerate holes. • p-GaN/p-Al x Ga 1-x N/p-GaN structure can efficiently improve hole injection into the multiple quantum wells (MQWs). • p-GaN/p-Al x Ga 1-x N/p-GaN structure can better reduce the threshold current and enhance the lasing power.