Development of Strain-compensated Distributed Bragg Reflectors for GaN-based VCSELs With Potential for Faster Growth and Higher Productivity

In this presentation, we introduce novel strain-compensated AlGaN/InGaN DBRs for GaN-based VCSELs. By adopting an asymmetric structure in which the InGaN layer is thicker than λ/4 and the AlGaN layer is thinner than λ/4, and by compensating for strain, we achieved a larger refractive index contrast compared to conventional λ/4 structures. Through a high growth rate of 1–several µm/h and minimizing growth interruption, we successfully fabricated DBRs with over 99.9% reflectivity in approximately 5 hours. With further optimization, this technology has the potential to reduce growth time to 2–3 hours, comparable to GaAs-based DBRs, and could significantly lower the manufacturing cost of GaN VCSEL wafers.