Single-Crystalline γ-Ga₂S₃ Nanotubes via Epitaxial Conversion of GaAs Nanowires

Abstract

The chemical transformation of nanowire templates into nanotubes is a promising avenue toward hollow one-dimensional (1D) nanostructures. To date, high-quality single crystalline tubes of non-layered inorganic crystals have been obtained by solid-state reactions in diffusion couples of nanowires with deposited thin film shells, but this approach presents issues in achieving singlephase tubes with a desired stoichiometry. Chemical transformations with reactants supplied from the gas-or vapor-phase can avoid these complications, allowing single-phase nanotubes to be obtained through self-termination of the reaction once the sacrificial template has been consumed. Here, we demonstrate the realization of this scenario with the transformation of zincblende GaAs nanowires into single-crystalline cubic γ-Ga 2 S 3 nanotubes by reaction with sulfur vapor. The conversion proceeds via the formation of epitaxial GaAs-Ga 2 S 3 core-shell structures, vacancy injection and aggregation into Kirkendall voids, elastic relaxation of the detached Ga 2 S 3 shell, and finally complete incorporation of Ga in a crystalline chalcogenide tube.Absorption and luminescence spectroscopy on individual nanotubes show optoelectronic properties, notably a ~3.1 eV bandgap and intense band-edge and near band-edge emission consistent with high-quality single crystals, along with transitions between gap-states due to the inherent cation-vacancy defect structure of Ga 2 S 3 . Our work establishes the transformation of nanowires via vapor-phase reactions as a viable approach for forming single-crystalline hollow 1D nanostructures with promising properties.

Ga2Se3 Nanowires via Au-Assisted Heterovalent Exchange Reaction on GaAs

“…The tubes formed by retraction of GaAs cores due to injection and coalescence of vacancies into the Kirkendall voids, with simultaneous evaporation of As. 32 In this paper, we demonstrate that freestanding Ga 2 Se 3 NWs can be obtained by MBE on Au-decorated GaAs surfaces without any external Ga supply, via a heterovalent exchange reaction mediated by Au nanoparticles. We show that at a suitable temperature the presence of Au on the surface favors the decomposition of the GaAs substrate and the release of Ga atoms, which react with the incoming Se and feed the NW growth.…”

“…The nanostructures showed excellent nonlinear optical properties. Finally, single crystalline Ga 2 S 3 nanotubes were obtained by conversion of GaAs NWs exposed to sulfur vapor . The conversion process was investigated as a function of the exposure time.…”

“…It was found to proceed via the formation of epitaxial core–shell GaAs–Ga 2 S 3 NWs, followed by the development of hollow Ga 2 S 3 tubes. The tubes formed by retraction of GaAs cores due to injection and coalescence of vacancies into the Kirkendall voids, with simultaneous evaporation of As …”

“…Finally, single crystalline Ga 2 S 3 nanotubes were obtained by conversion of GaAs NWs exposed to sulfur vapor. 32 The conversion process was investigated as a function of the exposure time. It was found to proceed via the formation of epitaxial core−shell GaAs−Ga 2 S 3 NWs, followed by the development of hollow Ga 2 S 3 tubes.…”

Gallium-based anodes for alkali metal ion batteries

“…Nevertheless, the controllable preparation of Ga 2 S 3 nanostructures remains a challenge. Up to now, the synthesis mainly focuses on the template-assited method followed by a thermal treatment [64,129,[131][132][133]. Hiring metal-organic frameworks (MOFs, MIL-96) as template precursor accompanied by a sulfuration process, Wang et al obtained dodecahedral Ga 2 S 3 /C structures, as is shown in Fig.…”