Fabrication of dielectric DBR for long-wavelength VCSELs by magnetron sputtering

In order to fabricate dielectric distributed Bragg reflectors (DBRs) with high thermal conductivity and reflectivity, magnetron sputtering of AlF₃/ZnS DBR structures was systematically investigated. The fluorine deficiency issue in AlF₃ films was addressed by introducing SF₆ gas, which significantly improved stoichiometry control. When the SF₆ flow rate exceeded 9 sccm, AlF₃ films achieved both target stoichiometric ratios and ideal refractive indices. Subsequently, the reflectivity of multilayer DBR combined with a gold layer reached 99%. Finally, lift-off-based patterning enables damage-free mesa definition, demonstrating applicability for long-wavelength vertical-cavity surface emitting lasers.