This week saw the appearance of a preprint concerning silicon diffusion in graphene, driven by 60 keV electron beam exposure. The authors conclude that the primary mechanism involves direct bond “inversion”. This entails an out-of-plane motion of a carbon atom, followed by translocation of the silicon and re-insertion of the carbon in the site just vacated by the silicon. The initial energy driving the carbon ejection comes from a strongly inelastic electron scattering event, with ~15 eV transferred
Recalling the careful and extensive measurements of thermally driven silicon diffusion in silicon at LBNL, one must wonder whether it is possible to measure analogous thermally driven, EUV driven, etc. silicon diffusion in graphene.
Susi, et al., “Silicon-carbon bond inversions driven by 60 keV electrons in graphene”, arXiv:1407.4274
Eugene E Haller, web page at UC Berkeley