Weakly Index Guided Buried-Stripe Type 980 nm Laser Diodes Grown by a Combination of Gas Source Molecular Beam Epitaxy and Metalorganic Vapor Phase Epitaxy with an AlGaAs/InGaP/GaAs Double Etch Stop Structure

Abstract

In order to fabricate weakly index guided buried-stripe type 980 nm laser diodes (LDs) precisely and reproducibly, we have developed a novel double etch stop (DES) structure which consists of AlGaAs/InGaP/GaAs layers. By employing the DES structure, an effective refractive index step (Δneff) of 3.6×10-3 and a waveguide bottom width (Wb) of 2.2 µm were realized to maintain a stable transverse mode. The LDs were fabricated by a combination of gas-source molecular beam epitaxy (GS-MBE) and metalorganic vapor phase epitaxy (MOVPE) on a 2-inch wafer and showed uniformly high performance, especially in the region within a 15.5 mm radius from the center. A high kink level of 315±15 mW was achieved. Considering wafer uniformity, we estimated that Δneff and Wb should be controlled to about 3.6×10-3± 3.5×10-4 and 2.22±0.06 µm, respectively, under the condition of a vertical optical confinement factor \\varGamma\\fallingdotseq1.16%/well. We have also confirmed the high quality of the entire process, including the DES method, by employing a reliability test at 200 mW light output power up to 2500 h.