title: Phase separation in single In(x)Ga(1-x)N nanowires revealed through a hard X-ray synchrotron nanoprobe.
abstract: In this work, we report on the composition, short- and long-range structural order of single molecular beam epitaxy grown In(x)Ga(1-x)N nanowires using a hard X-ray synchrotron nanoprobe. Nano-X-ray fluorescence mapping reveals an axial and radial heterogeneous elemental distribution in the single wires with Ga accumulation at their bottom and outer regions. Polarization-dependent nano-X-ray absorption near edge structure demonstrates that despite the elemental modulation, the tetrahedral order around the Ga atoms remains along the nanowires. Nano-X-ray diffraction mapping on single nanowires shows the existence of at least three different phases at their bottom: an In-poor shell and two In-rich phases. The alloy homogenizes toward the top of the wires, where a single In-rich phase is observed. No signatures of In-metallic precipitates are observed in the diffraction spectra. The In-content along the single nanowires estimated from X-ray fluorescence and diffraction data are in good agreement. A rough picture of these phenomena is briefly presented. We anticipate that this methodology will contribute to a greater understanding of the underlying growth concepts not only of nanowires but also of many nanostructures in materials science.
authors: Experiments Division, European Synchrotron Radiation Facility , 38043 Grenoble, France.
authors: J
authors: J
authors: Segura-Ruiz
authors: G
authors: G
authors: Martínez-Criado
authors: C
authors: C
authors: Denker
authors: J
authors: J
authors: Malindretos
authors: A
authors: A
authors: Rizzi
mesh_terms: D005708:Gallium / Q000737:chemistry; D007204:Indium / Q000737:chemistry; D053770:Nanowires / Q000737:chemistry* / Q000648:ultrastructure*; D017356:Synchrotrons; D014965:X-Rays
chemical_list: D007204:Indium; D005708:Gallium