Strain compensated type Ⅱ superlattices grown by molecular beam epitaxy

We investigate a strain compensation method for the growth of complex interband cascade laser structures. For thick In As/Al Sb superlattice clad layers, the sublayer thicknesses were adjusted so that the tensile strain energy in the In As sublayer was equal to the compressive strain energy in the Al Sb sublayer. For the four-constituent active region, as the compressive strain in the Ga0.65In0.35Sb alloy layer was large, a tensile strain was incorporated in the chirped In As/Al Sb superlattice region for strain compensation to the Ga0.65In0.35Sb alloy. A laser structure of thickness 6 μm was grown on the Ga Sb substrate by molecular beam epitaxy. The wafer exhibited good surface morphology and high crystalline quality.