Interface engineered MBE grown InAs/GaSb based type-II superlattice heterostructures

Abstract Strain balanced InAs/GaSb type-II superlattice structures have been grown using molecular beam epitaxy. InSb like interfaces have been introduced at both InAs on GaSb and GaSb on InAs surfaces using migration enhanced epitaxy to compensate the tensile strain between the constituent binaries of the superlattice. The superlattice layers have been characterized using high resolution X-ray diffraction, atomic force microscopy, transmission electron microscopy and absorption spectroscopy. It is shown that the substrate temperature influences the InSb thickness at the interface and therefore the net strain in the superlattice. The dependence of the surface morphology on the strained or relaxed state of the superlattice is discussed. The optimized InAs(10 ML)/InSb(0.5 ML)/GaSb(12 ML)/InSb(0.5 ML) superlattice epilayers up to 200 periods have been grown at temperature of 450 °C and have a small net strain of 0.0013%. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) analysis in the strain compensated superlattice layers reveal InSb like interfaces. Excellent crystalline quality and morphology with an absorption edge at 5.4 µm in the mid-wave infra-red (MWIR) region are observed for the optimized epilayers.