Etching mechanisms of graphene nanoribbons in downstream H2 plasmas: Insights from molecular dynamics simulations

A. Davydova, E. Despiau-Pujo, G. Cunge, D. B. Graves

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

Lateral etching mechanisms of graphene nanoribbons (GNRs) with zigzag (ZZ) edges in downstream H2 plasmas are investigated using molecular dynamics simulations. A new etching mechanism is found, which occurs in three consecutive phases and requires a continuous exposure of GNRs to H atoms and high substrate temperatures (∼800 K). Full hydrogenation of GNR free edges during phase 1 reduces the potential barriers to H chemisorption on near-edge C atoms from the basal plane. Subsequent hydrogenation of near-edge C-C dimers creates mechanical stress between C atoms (due to local sp2-to-sp3 rehybridizations) which leads to the rupture of C-C dimers bonds, unzipping locally the 1st and 2nd edge carbon rows. The unzipping then propagates randomly along the GNR edges and creates suspended linear carbon chains (phase 2). Weakened by their exposure to continuous H bombardment and strong thermal vibrations, the suspended carbon chains may then rupture, leading to the sputtering of their carbon atoms as single C atoms or C2 molecules (phase 3). Thus no formation of volatile hydrocarbon etching products is observed in this three-phase mechanism, which explains why the ribbon edges can be sharp-cut without generation of line-edge roughness, as also observed experimentally. Influence of substrate temperature on ZZ-GNRs etching is investigated and suggests the dominant mechanisms for understanding the temperature dependence of the etch rate observed experimentally (peaks at 800 K and decreases for lower or higher temperatures).

Original languageEnglish (US)
Pages (from-to)195202
Number of pages1
JournalJournal of Physics D: Applied Physics
Volume48
Issue number19
DOIs
StatePublished - May 20 2015
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Acoustics and Ultrasonics
  • Surfaces, Coatings and Films

Keywords

  • Etching
  • Graphene nanoribbons
  • H plasmas
  • Molecular dynamics

Fingerprint

Dive into the research topics of 'Etching mechanisms of graphene nanoribbons in downstream H2 plasmas: Insights from molecular dynamics simulations'. Together they form a unique fingerprint.

Cite this