Epitaxial type-I and type-II InAs-AlAsSb core–shell nanowires on silicon

InAs-AlAsSb core-shell nanowire (NW) systems with widely tunable AlAsSb shell composition may offer many ideal properties suited for forthcoming applications in nanoelectronics, energy harvesting, as well as mid-infrared (MIR) photonics and optoelectronics integrated on silicon (Si). Here, we present high-uniformity InAs-AlAsSb NW arrays grown by selective-area molecular beam epitaxy. Further, we study systematically the effects of shell composition on the morphological, structural as well as strain and optical properties using correlated electron microscopy techniques, combined with micro-Raman scattering and micro-photoluminescence spectroscopy (PL). While controlling the emission wavelength over a large range (~0.4–0.55 eV), we highlight the tunability between type-I and type-II like transitions in this system supported by simulations.