We investigated by means of transmission electron microscopy (TEM) GaAs-AlGaAs core-shell nanowires (NWs) grown by Au-catalyzed metalorganic vapor phase epitaxy under As-rich vapor conditions. The structural analysis reveals that the NWs exhibit zincblende phase only and a very low density of twin defects along the NW trunk; a higher amount of twins around the NW axial (growth) direction occur instead within a tapered region closeby the NW tip. We correlate this finding to the Alrich composition of the tapered region, as deduced by scanning-TEM (STEM) mass contrast analysis, this region being the effect of residual Au-assisted self-assembly of the material during shell overgrowth. In addition a few percent of NWs show branching during their growth, and we determine the crystal properties and defects of branched NWs. We propose that this phenomenon may be induced by Au nanoparticle instabilities during NW growth and further demonstrate that twin defects occur at the NW branching points.

Structural characterization of MOVPE-grown GaAs/AlGaAs core-shell nanowires through transmission electron microscopy

PRETE, Paola;MICCOLI, ILIO;LOVERGINE, Nicola;
2018-01-01

Abstract

We investigated by means of transmission electron microscopy (TEM) GaAs-AlGaAs core-shell nanowires (NWs) grown by Au-catalyzed metalorganic vapor phase epitaxy under As-rich vapor conditions. The structural analysis reveals that the NWs exhibit zincblende phase only and a very low density of twin defects along the NW trunk; a higher amount of twins around the NW axial (growth) direction occur instead within a tapered region closeby the NW tip. We correlate this finding to the Alrich composition of the tapered region, as deduced by scanning-TEM (STEM) mass contrast analysis, this region being the effect of residual Au-assisted self-assembly of the material during shell overgrowth. In addition a few percent of NWs show branching during their growth, and we determine the crystal properties and defects of branched NWs. We propose that this phenomenon may be induced by Au nanoparticle instabilities during NW growth and further demonstrate that twin defects occur at the NW branching points.
2018
978-150905151-9
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11587/413379
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 0
  • ???jsp.display-item.citation.isi??? ND
social impact