Vertically-aligned CdTe nanowire (NWs) were grown for the first time by metalorganic vapor phase epitaxy, using diisopropyl-telluride and dimethylcadmium as precursors, and Au nanoparticles as metal catalysts. The NWs were grown between 485 and 515, °C on (111)B-GaAs substrates, the latter overgrown with a 2-μm thick CdTe epilayer. To favor the Au-catalyst assisted process against planar deposition of CdTe, an alternate precursors flow process was adopted during NW self-assembly. Field emission electron microscopy observations and X-ray energy dispersive analyses of CdTe NWs revealed the presence of Au-rich droplets at their tips, the contact-angle between Au-droplets and NWs being, ~130°. The NW height increases exponentially with the growth temperature, indicating that the Au-catalyzed process is kinetics-limited (activation energy: ~57, kcal/mol), but no tapering is observed. Low temperature cathodoluminescence spectra recorded from single NWs evidenced a band-edge emission typical of zincblend CdTe, and a dominant (defects-related) emission band at 1.539 eV.

Au-Catalyst Assisted MOVPE Growth of CdTe Nanowires for Photovoltaic Applications

DI CARLO, VIRGINIA;Fabio Marzo;Massimo Di Giulio;Paola Prete;Nicola Lovergine
2018-01-01

Abstract

Vertically-aligned CdTe nanowire (NWs) were grown for the first time by metalorganic vapor phase epitaxy, using diisopropyl-telluride and dimethylcadmium as precursors, and Au nanoparticles as metal catalysts. The NWs were grown between 485 and 515, °C on (111)B-GaAs substrates, the latter overgrown with a 2-μm thick CdTe epilayer. To favor the Au-catalyst assisted process against planar deposition of CdTe, an alternate precursors flow process was adopted during NW self-assembly. Field emission electron microscopy observations and X-ray energy dispersive analyses of CdTe NWs revealed the presence of Au-rich droplets at their tips, the contact-angle between Au-droplets and NWs being, ~130°. The NW height increases exponentially with the growth temperature, indicating that the Au-catalyzed process is kinetics-limited (activation energy: ~57, kcal/mol), but no tapering is observed. Low temperature cathodoluminescence spectra recorded from single NWs evidenced a band-edge emission typical of zincblend CdTe, and a dominant (defects-related) emission band at 1.539 eV.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11587/417945
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