Structural Properties of Wurtzite InP–InGaAs Nanowire Core–Shell Heterostructures

We report on growth and characterization of wurtzite InP–In_1–<i>x</i>Ga_<i>x</i>As core–shell nanowire heterostructures. A range of nanowire structures with different Ga concentration in the shell was characterized with transmission electron microscopy and X-ray diffraction. We found that the main part of the nanowires has a pure wurtzite crystal structure, with occasional stacking faults occurring only at the top and bottom. This allowed us to determine the structural properties of wurtzite In_1–<i>x</i>Ga_<i>x</i>As. The InP–In_1–<i>x</i>Ga_<i>x</i>As core–shell nanowires show a triangular and hexagonal facet structure of {1100} and {101̅0} planes. X-ray diffraction measurements showed that the core and the shell are pseudomorphic along the <i>c</i>-axis, and the strained axial lattice constant is closer to the relaxed In_1–<i>x</i>Ga_<i>x</i>As shell. Microphotoluminescence measurements of the nanowires show emission in the infrared regime, which makes them suitable for applications in optical communication