Threshold current density of 1.3-μm GaAsSbN/GaAs quantum-well lasers

The threshold current density of a GaAsSbN/GaAs quantum well (QW) structure is investigated using the multiband effective mass theory and the non-Markovian gain model. This is compared with that of a type-II GaAsSb/GaAs QW structure for a self-consistent method. The GaAsSbN/GaAs QW structure is found to have a larger optical gain than the GaAsSb/GaAs QW structure. This can be explained by the fact that the former has a larger optical matrix element and an improved quasi-Fermi-level separation (ΔEfc + ΔEfv) than the latter. The improvement in the total quasi-Fermi-level separation of the GaAsSbN/GaAs QW structure is mainly attributed to a larger energy spacing in the conduction band. The GaAsSbN/GaAs QW structure shows a significantly smaller threshold current density compared to that of the GaAsSb/GaAs QW structure because the GaAsSbN/GaAs QW structure has a much smaller threshold carrier density than the GaAsSb/GaAs QW structure.