Hot-Electron-Mediated Ion Diffusion in Semiconductors for Ion-Beam Nanostructuring

Cheng Wei Lee, André Schleife

Research output: Contribution to journalArticle

Abstract

Ion-beam-based techniques are widely utilized to synthesize, modify, and characterize materials at the nanoscale, with applications from the semiconductor industry to medicine. Interactions of the beam with the target are fundamentally interesting, as they trigger multilength and time-scale processes that need to be quantitatively understood to achieve nanoscale precision. Here we demonstrate for magnesium oxide, as a testbed semiconductor material, that in a kinetic-energy regime in which electronic effects are usually neglected, a proton beam efficiently excites oxygen-vacancy-related electrons. We quantitatively describe the excited-electron distribution and the emerging ion dynamics using first-principles techniques. Contrary to the common picture of charging the defect, we discover that most of the excited electrons remain locally near the oxygen vacancy. Using these results, we bridge time scales from ultrafast electron dynamics directly after impact to ion diffusion over migration barriers in semiconductors and discover a diffusion mechanism that is mediated by hot electrons. Our quantitative simulations predict that this mechanism strongly depends on the projectile-ion velocity, suggesting the possibility of using it for precise sample manipulation via nanoscale diffusion enhancement in semiconductors with a deep, neutral, intrinsic defect.

Original languageEnglish (US)
Pages (from-to)3939-3947
Number of pages9
JournalNano letters
Volume19
Issue number6
DOIs
StatePublished - Jun 12 2019

Keywords

  • Multiscale
  • constrained density functional theory
  • enhanced point defect diffusion
  • first principles
  • hot electrons
  • ionizing particle radiation

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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