Facetted growth of Fe3Si shells around GaAs nanowires on Si(111)

TL;DR

This study demonstrates the controlled growth of facetted Fe3Si shells around GaAs nanowires on Si(111), revealing nanofacet formation and pseudomorphic crystallography through molecular-beam epitaxy.

Contribution

It introduces a method for growing facetted Fe3Si shells on GaAs nanowires with specific crystallographic orientation and surface morphology.

Findings

Fe3Si shells exhibit nanofacets mainly of Fe3Si(111) planes.

Shell growth is pseudomorphic with the GaAs core.

Facetted shells result from Vollmer-Weber island growth mode.

Abstract

GaAs nanowires and GaAs/Fe3Si core/shell nanowire structures were grown by molecular-beam epitaxy on oxidized Si(111) substrates and characterized by transmission electron microscopy. The surfaces of the original GaAs NWs are completely covered by magnetic Fe3Si exhibiting nanofacets and an enhanced surface roughness compared to the bare GaAs NWs. Shell growth at a substrate temperature of T{S} = 200 {\deg}C leads to regular nanofacetted Fe3Si shells. These facets, which lead to thickness inhomogeneities of the shells, consist mainly of well pronounced Fe3Si(111) planes. The crystallographic orientation of core and shell coincide, i.e. they are pseudomorphic. The nanofacetted Fe3Si shells found in the present work are probably the result of the Vollmer-Weber island growth mode of Fe3Si on the {110} side facets of the GaAs NWs.