Catalyst Incorporation at Defects during Nanowire Growth

Scanning and transmission electron microscopy was used to correlate the structure of planar defects with the prevalence of Au catalyst atom incorporation in Si nanowires. Site-specific high-resolution imaging along orthogonal zone axes, enabled by advances in focused ion beam cross sectioning, reveals substantial incorporation of catalyst atoms at grain boundaries in ⟨110⟩ oriented nanowires. In contrast, (111) stacking faults that generate new polytypes in ⟨112⟩ oriented nanowires do not show preferential catalyst incorporation. Tomographic reconstruction of the catalyst–nanowire interface is used to suggest criteria for the stability of planar defects that trap impurity atoms in catalyst-mediated nanowires

Catalyst Incorporation at Defects during Nanowire Growth

Scanning and transmission electron microscopy was used to correlate the structure of planar defects with the prevalence of Au catalyst atom incorporation in Si nanowires. Site-specific high-resolution imaging along orthogonal zone axes, enabled by advances in focused ion beam cross sectioning, reveals substantial incorporation of catalyst atoms at grain boundaries in ⟨110⟩ oriented nanowires. In contrast, (111) stacking faults that generate new polytypes in ⟨112⟩ oriented nanowires do not show preferential catalyst incorporation. Tomographic reconstruction of the catalyst–nanowire interface is used to suggest criteria for the stability of planar defects that trap impurity atoms in catalyst-mediated nanowires

Size-Dependent Polar Ordering in Colloidal GeTe Nanocrystals

The question of the nature and stability of polar ordering in nanoscale ferroelectrics is examined with colloidal nanocrystals of germanium telluride (GeTe). We provide atomic-scale evidence for room-temperature polar ordering in individual nanocrystals using aberration-corrected transmission electron microscopy and demonstrate a reversible, size-dependent polar-nonpolar phase transition of displacive character in nanocrystal ensembles. A substantial linear component of the distortion is observed, which is in contrast with theoretical reports predicting a toroidal state