Midinfrared InGaAsSb quantum well lasers with digitally grown tensile-strained AlGaAsSb barriers

Abstract

The InGaAsSb lasers emitting in the midinfrared with strain-compensated multiple-quantum-well (MQW) active region have been grown by solid-source molecular-beam epitaxy (MBE). Digitally grown tensile-strained AlGaAsSb was employed as barriers to increase the valence-band offset for hole confinement. The laser structures were characterized by reflection high-energy electron diffraction, x-ray diffraction, and photoluminescence. The digital-growth approach for the tensile-strained AlGaAsSb barriers improved the reliability and controllability of MBE growth for the MQW active region. The optical and structural qualities of InGaAsSb MQW were improved significantly as compared to those with random-alloy barriers due to the removal of growth interruption at the barrier/well interfaces in digital growth. As a result, high-performance devices were achieved in the InGaAsSb lasers with digital AlGaAsSb barriers. A low threshold current density of 163A∕cm2 at room temperature was achieved for 1000-μm-long lasers emi...