The effect of increased valence band offset on the operation of 2 μm GaInAsSb-AlGaAsSb lasers

Two and four quantum-well (QW) GaInAsSb-AlGaAsSb lasers emitting at 2 μm are reported. In comparison to previously published data, it is found that higher Al content in the QW barrier improves the internal efficiency, saturated modal gain, and characteristic temperature of the lasers. These results are attributed to an increased valence band offset that provides superior hole confinement in the GaInAsSb QW. A differential efficiency of 74% is observed at 25/spl deg/C under pulsed conditions for a 900-μm cavity length, 2-QW device, and a record characteristic temperature of 140 K is measured for a 4-QW laser.