Influence of Indium and Arsenic composition on structural properties of InGaAsSb/AlGaAsSb multi-quantum wells grown by molecular beam epitaxy

InGaAsSb/AlGaAsSb multiple quantum well (MQW) structures, with their narrow band gap quaternary compositions, are well suited for devices operating in the 2–3 µm mid-infrared spectral region. In this study, to investigate the effects of compositional variation on structural properties, twenty-period MQW structures were grown by molecular beam epitaxy on (100) GaSb substrates. It was demonstrated that varying the In and As concentrations while keeping the V/III beam equivalent pressure ratio constant significantly influenced the surface morphology due to defect formation. It was found that in the samples with In concentrations ranging from 30 to 44%, low As content resulted in an increase in the number of surface defects. However, a smooth, defect-free surface and improved crystal quality were achieved at 44% In content when the As concentration in the QWs was 14% or higher. These results highlight the importance of precise compositional tuning for achieving high structural quality in mid-infrared MQW devices.