title: Shape Engineering Driven by Selective Growth of SnO2on Doped Ga2O3Nanowires.
abstract: Tailoring the shape of complex nanostructures requires control of the growth process. In this work, we report on the selective growth of nanostructured tin oxide on gallium oxide nanowires leading to the formation of SnO2/Ga2O3complex nanostructures. Ga2O3nanowires decorated with either crossing SnO2nanowires or SnO2particles have been obtained in a single step treatment by thermal evaporation. The reason for this dual behavior is related to the growth direction of trunk Ga2O3nanowires. Ga2O3nanowires grown along the [001] direction favor the formation of crossing SnO2nanowires. Alternatively, SnO2forms rhombohedral particles on [110] Ga2O3nanowires leading to skewer-like structures. These complex oxide structures were grown by a catalyst-free vapor-solid process. When pure Ga and tin oxide were used as source materials and compacted powders of Ga2O3acted as substrates, [110] Ga2O3nanowires grow preferentially. High-resolution transmission electron microscopy analysis reveals epitaxial relationship lattice matching between the Ga2O3axis and SnO2particles, forming skewer-like structures. The addition of chromium oxide to the source materials modifies the growth direction of the trunk Ga2O3nanowires, growing along the [001], with crossing SnO2wires. The SnO2/Ga2O3junctions does not meet the lattice matching condition, forming a grain boundary. The electronic and optical properties have been studied by XPS and CL with high spatial resolution, enabling us to get both local chemical and electronic information on the surface in both type of structures. The results will allow tuning optical and electronic properties of oxide complex nanostructures locally as a function of the orientation. In particular, we report a dependence of the visible CL emission of SnO2on its particular shape. Orange emission dominates in SnO2/Ga2O3crossing wires while green-blue emission is observed in SnO2particles attached to Ga2O3trunks. The results show that the Ga2O3-SnO2system appears to be a benchmark for shape engineering to get architectures involving nanowires via the control of the growth direction of the nanowires.
authors.affiliation: Departamento de Física de Materiales, Facultad de Ciencias Físicas, Universidad Complutense de Madrid , 28040-Madrid, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Alonso-Orts
authors.affiliation: Department of Physics, University of Warwick , Coventry, CV4 7AL, United Kingdom.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Sánchez
authors.affiliation: Department of Physics, University of Warwick , Coventry, CV4 7AL, United Kingdom.
authors.forename: Steven A
authors.initials: SA
authors.lastname: Hindmarsh
authors.affiliation: Departamento de Física de Materiales, Facultad de Ciencias Físicas, Universidad Complutense de Madrid , 28040-Madrid, Spain.
authors.forename: Iñaki
authors.initials: I
authors.lastname: López
authors.affiliation: Departamento de Física de Materiales, Facultad de Ciencias Físicas, Universidad Complutense de Madrid , 28040-Madrid, Spain.
authors.forename: Emilio
authors.initials: E
authors.lastname: Nogales
authors.affiliation: Departamento de Física de Materiales, Facultad de Ciencias Físicas, Universidad Complutense de Madrid , 28040-Madrid, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Piqueras
authors.affiliation: Departamento de Física de Materiales, Facultad de Ciencias Físicas, Universidad Complutense de Madrid , 28040-Madrid, Spain.|Department of Physics, University of Warwick , Coventry, CV4 7AL, United Kingdom.
authors.forename: Bianchi
authors.identifier: 0000-0002-6289-7437
authors.initials: B
authors.lastname: Méndez
keywords: Complex oxide nanowires; cathodoluminescence; crossed nanowires; selective growth; transmission electron microsopy