Improved carrier confinement and stimulated recombination rate in GaN-based vertical-cavity surface-emitting lasers with buried p-AlGaN inversion layer

A GaN-based vertical cavity surface emitting laser (VCSEL) featuring a buried ring-shape p-Al0.10Ga0.90N inside n-GaN contact layer for lateral electron confinement is proposed. The p-AlGaN layer inserted in n-GaN forms an n-p-n structure, acting as a potential barrier to prevent vertical electron migration outside the aperture of the VCSEL, where optical gain is accumulated. By adjusting the thickness and position of the p-AlGaN layer, electron concentration and stimulated recombination rate in the aperture of the VCSEL increased significantly. Consequently, the output power of VCSEL with buried p-AlGaN layer increases by 57% compared to the conventional VCSEL at an injection current of 10 mA. The detailed mechanism responsible for this enhancement is further explored. This work suggests that the introduction of the buried p-AlGaN layer in VCSEL can provide new line of thought in achieving effective current confinement in the development of high-efficient, low-threshold solid-state lasers