title: Synthesis of Hierarchical ZnO/CdSSe Heterostructure Nanotrees.
abstract: A two-step chemical vapor deposition procedure is here employed to prepare tree-like hierarchical ZnO/CdSSe hetero-nanostructures. The structures are composed of CdSSe branches grown on ZnO nanowires that are vertically aligned on a transparent sapphire substrate. The morphology was measured via scanning electron microscopy. The crystal structure was determined by X-ray powder diffraction analysis. Both the ZnO stem and CdSSe branches have a predominantly wurtzite crystal structure. The mole ratio of S and Se in the CdSSe branches was measured by energy dispersive X-ray spectroscopy. The CdSSe branches result in strong visible light absorption. Photoluminescence (PL) spectroscopy showed that the stem and branches form a type-II heterojunction. PL lifetime measurements showed a decrease in the lifetime of emission from the trees when compared to emission from individual ZnO stems or CdSSe branches and indicate fast charge transfer between CdSSe and ZnO. The vertically aligned ZnO stems provide a direct electron transport pathway to the substrate and allow for efficient charge separation after photoexcitation by visible light. The combination of the abovementioned properties makes ZnO/CdSSe nanotrees promising candidates for applications in solar cells, photocatalysis, and opto-electronic devices.
authors.affiliation: Department of Chemistry & Biochemistry, University of Delaware; Department of Physics & Astronomy, University of Delaware.
authors.forename: Zhengxin
authors.initials: Z
authors.lastname: Li
authors.affiliation: Department of Chemistry & Biochemistry, University of Delaware; Department of Physics & Astronomy, University of Delaware.
authors.forename: Jesus
authors.initials: J
authors.lastname: Nieto-Pescador
authors.affiliation: Department of Chemistry & Biochemistry, University of Delaware; Department of Physics & Astronomy, University of Delaware.
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Carson
authors.affiliation: Department of Chemistry & Biochemistry, University of Delaware; Department of Physics & Astronomy, University of Delaware.
authors.forename: Jolie C
authors.initials: JC
authors.lastname: Blake
authors.affiliation: Department of Chemistry & Biochemistry, University of Delaware; Department of Physics & Astronomy, University of Delaware; larsg@udel.edu.
authors.forename: Lars
authors.initials: L
authors.lastname: Gundlach
mesh_terms: D000537:Aluminum Oxide; D019187:Cadmium Compounds; D008027:Light; D049329:Nanostructures; D053770:Nanowires; D015034:Zinc Oxide
chemical_list: D019187:Cadmium Compounds; D000537:Aluminum Oxide; D015034:Zinc Oxide