Atom probe tomography of a-axis GaN nanowires: Analysis of nonstoichiometric evaporation behavior

James R. Riley, Rodrigo A. Bernal, Qiming Li, Horacio Dante Espinosa, George T. Wang, Lincoln James Lauhon*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

63 Scopus citations


GaN nanowires oriented along the nonpolar a-axis were analyzed using pulsed laser atom probe tomography (APT). Stoichiometric mass spectra were achieved by optimizing the temperature, applied dc voltage, and laser pulse energy. Local variations in the measured stoichiometry were observed and correlated with facet polarity using scanning electron microscopy. Fewer N atoms were detected from nonpolar and Ga-polar surfaces due to uncorrelated evaporation of N 2 ions following N adatom diffusion. The observed differences in Ga and N ion evaporation behaviors are considered in detail to understand the influence of intrinsic materials characteristics on the reliability of atom probe tomography analysis. We find that while reliable analysis of III-N alloys is possible, the standard APT procedure of empirically adjusting analysis conditions to obtain stoichiometric detection of Ga and N is not necessarily the best approach for this materials system

Original languageEnglish (US)
Pages (from-to)3898-3906
Number of pages9
JournalACS Nano
Issue number5
StatePublished - May 22 2012


  • Atom probe tomography
  • GaN
  • Semiconductor nanowires

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)


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