Imaging Atomic-Level Random Walk of a Point Defect in Graphene

Abstract

Deviations from the perfect atomic arrangements in crystals play an important role in affecting their properties. Similarly, diffusion of such deviations is behind many microstructural changes in solids. However, observation of point defect diffusion is hindered both by the difficulties related to direct imaging of non-periodic structures and by the time scales involved in the diffusion process. Here, instead of imaging thermal diffusion, we stimulate and follow the migration of a divacancy through graphene lattice using a scanning transmission electron microscope operated at 60 kV. The beam-activated process happens on a timescale that allows us to capture a significant part of the structural transformations and trajectory of the defect. The low voltage combined with ultra-high vacuum conditions ensure that the defect remains stable over long image sequences, which allows us for the first time to directly follow the diffusion of a point defect in a crystalline material.

References in corpus (3)

• Two-dimensional transition metal dichalcogenides under electron irradiation: defect production and doping
• From Point Defects in Graphene to Two-Dimensional Amorphous Carbon
• Stone-Wales--type transformations in carbon nanostructures driven by electron irradiation

Cited by in corpus (5)

• Manipulating low-dimensional materials down to the level of single atoms with electron irradiation
• Towards atomically precise manipulation of 2D nanostructures in the electron microscope
• Doping transition-metal atoms in graphene for atomic-scale tailoring of electronic, magnetic, and quantum topological properties
• The role of temperature on defect diffusion and nanoscale patterning in graphene
• Radiation-induced mobility of small defect clusters in covalent materials