Fabrication of 1.55 μm In0.53Ga0.47As/In0.53(Ga0.6Al0.4)0.47As SCH MQW laser with InGaAlAs digital alloy by post-growth rapid thermal annealing using dielectric capping layers

We fabricated MBE-grown InGaAs/InGaAlAs SCH MQW ridge-waveguide lasers with InGaAlAs digital alloy layers after post-growth rapid thermal annealing using an SiO₂ capping layer. The lasers fabricated on as-grown substrate and annealed substrates were compared by I-V and I-L measurements. The electrical characteristics of the annealed lasers were not degraded by the annealing process compared to those of as-grown lasers. The threshold current and slope efficiency of the fabricated lasers were improved with the increase of RTA temperature. For a 10-μm-wide and 600-μm-length laser fabricated after an RTA of 850°C for 45 sec, the internal quantum efficiency of about 27.6% per facet and the threshold current density of about 1.53 kA/cm² were obtained at room temperature.