Impacts of SiO2-Buried Structure on Performances of GaN-Based Vertical-Cavity Surface-Emitting Lasers

Numerical analysis of the optical and electrical properties of GaN-based vertical-cavity surface-emitting lasers (VCSELs) with SiO2-buried structure were performed. The simulation results show that, as the SiO2 layer gets thicker, threshold simply gets lower, but slope efficiency gets initially smaller and then gets larger. The mechanism of these tendencies are explained as, when the SiO2 layer becomes thicker, a better lateral optical confinement can be achieved, while the current confinement becomes worse due to the existence of polarization electric field. Furthermore, since the injection current density is higher for VCSEL with small aperture size, the worse current confinement will result in lower slope efficiency. A proper design of SiO2-buried structure to avoid the effect of leakage current is essentially important to achieve high-efficiency GaN-based VCSELs.