Molecular beam epitaxial growth of GaAsSb/GaAsSbN/GaAlAs core-multishell nanowires for near-infrared applications

We report on the bandgap engineering of the GaAsSb/GaAsSbN heterostructured nanowires (NWs) in the core–shell architecture using the unique properties of dilute nitride material system for near-infrared photodetection. A high density of vertical GaAsSb/GaAsSb(N)/GaAlAs core-multishell configured NWs with well faceted, smooth surface morphology has been grown on Si (111) substrates using Ga-assisted molecular beam epitaxy. A low Sb content GaAsSb core has been shown to enable the coherently strained growth of dilute nitride shell with higher Sb content in GaAsSbN shell NWs. A systematic study of N and V/III beam equivalent pressure ratios is carried out to achieve the large band-gap reduction, while successfully incorporating higher Sb content in the dilute nitride shells (GaAs_1−xSb_xN; x = 0.27). The incorporation of N acts to relieve strain and provide a smooth surface morphology as well as redshift the 4K photoluminescence (PL) peak energy by ∼160 meV in comparison to a non-nitride shell. The selected area diffraction pattern confirms zinc-blende structure in all the NWs and did not show any noticeable planar defects in dilute nitride NWs. We successfully, thus demonstrate GaAsSb/GaAsSbN/GaAlAs core–shell NWs by engineering the lattice strain of nitride shell with the non-nitride ternary core, for extending the 4K photoemission up to 1.43 μm. (paper)