GaAs Core/SrTiO₃ Shell Nanowires Grown by Molecular Beam Epitaxy

Abstract

We have studied the growth of a SrTiO3 shell on self-catalyzed GaAs nanowires grown by vapor-liquid-solid assisted molecular beam epitaxy on Si(111) substrates. To control the growth of the SrTiO3 shell, the GaAs nanowires were protected using an arsenic capping/decapping procedure in order to prevent uncontrolled oxidation and/or contamination of the nanowire facets. Reflection high energy electron diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy were performed to determine the structural, chemical, and morphological properties of the heterostructured nanowires. Using adapted oxide growth conditions, it is shown that most of the perovskite structure SrTiO3 shell appears to be oriented with respect to the GaAs lattice. These results are promising for achieving one-dimensional epitaxial semiconductor core/functional oxide shell nanostructures.

GaAs nanowires with oxidation-proof arsenic capping for the growth of an epitaxial shell

“…GaAs (core)/SrTiO 3 (shell) NWs were recently achieved by using the As-capping method. 65 The first results show that a partial epitaxial-shell was grown on As-capped/ decapped GaAs NWs, on the contrary to the air-oxidized-GaAs NWs (Fig. S11 †), as positive proof that the As-capping method can facilitate epitaxial heterogeneous shells, such as functional oxides, on III-V semiconductor NWs.…”

X-ray photoelectron spectroscopy study of Ga nanodroplet on silica-terminated silicon surface for nanowire growth

“…In this part we have replicated the early stages of standard NW growth conditions 14,25,26 : Ga was deposited at a substrate temperature of 510 °C and the substrate temperature was then increased to reach the temperature at which GaAs NWs are grown. This post-deposition annealing has been performed between 560 °C and 660 °C.…”

Insights into the Arsenic Shell Decapping Mechanisms in As/GaAs Nanowires by X-ray and Electron Microscopy

“…III–V semiconducting nanowires (NWs) are promising for a large range of applications including solar energy harvesting, − microelectronics, and integrated photonics. − In most of these applications, an epitaxial shell or a passivation layer wrapping the III–V core of the NW is needed to modify their functional properties or to avoid the formation of surface recombination traps due to undesirable oxidation. Materials such as silicon and germanium, , aluminum, , Fe 3 Si, and SrTiO 3 have been used as shell-material wrapping of III–V NWs to enhance or optimize their properties. Nevertheless, growing such heterogeneous shells is challenging; in most cases, the shell and the core must be deposited in separate reactors, which implies that the oxidation of the as-deposited III–V facets must be avoided when the NWs are transferred between the deposition chambers.…”