Inelastic electron irradiation damage in hexagonal boron nitride

Abstract

We present a study of the inelastic effects caused by electron irradiation in monolayer hexagonal boron nitride (h-BN). The data was obtained through in situ experiments performed inside a low-voltage aberration-corrected transmission electron microscope (TEM). By using various specialized sample holders, we study defect formation and evolution with sub-nanometer resolution over a wide range of temperatures, between -196 and 1200 °C, highlighting significant differences in the geometry of the structures that form. The data is then quantified, allowing insight into the defect formation mechanism, which is discussed in comparison with the potential candidate damage processes. We show that the defect shapes are determined by an interplay between electron damage, which we assign to charging, and thermal effects. We additionally show that this damage can be avoided altogether by overlapping the samples with a monolayer of graphene, confirming this for h-BN and providing a way to overcome the well-known fragility of h-BN under the electron beam.

Structural Attributes and Photodynamics of Visible Spectrum Quantum Emitters in Hexagonal Boron Nitride

“…The vacancy sizes created cannot only be pointlike (atomic) but also nano-sized as seen in the TEM images of Refs. 35,36. Annealing at 850 °C may cause vacancies to diffuse inside the flake 37 similar to diffusion known for the NV defect annealing in diamond, 38 leaving defects not exposed to the external environment.…”

Electron radiation damage mechanisms in 2D MoSe2

“…2) The difference between a free-standing MoS 2 and G/MoS 2 gives the inelastic contribution. This, in turn, is based on the assumption that graphene, which is a supreme electric and thermal conductor, quenches the electronic excitations and dissipates any introduced heat and eliminates sample charging, thus removing the inelastic damage 16 . Of the two, the latter is more conjecture because the damage created by inelastic collisions with high energy electrons is not fully understood.…”

Postsynthesis of h‐BN/Graphene Heterostructures Inside a STEM

“…We also report the postsynthesis of isolated carbon islands, performed by first drilling holes on the h‐BN layer and reknitting these holes by newly grown graphene. H‐BN has threefold symmetry and typically forms triangular holes under the electron beam; however, under certain conditions, such as high temperatures, circular, and hexagonal holes are observed . Graphene typically has sixfold symmetry, but the newly grown graphene filling the triangular holes of h‐BN shows special magnetic properties .…”

“…H-BN has threefold symmetry and typically forms triangular holes under the electron beam; [ 21 ] however, under certain conditions, such as high temperatures, circular, and hexagonal holes are observed. [ 22 ] Graphene typically has sixfold symmetry, but the newly grown graphene fi lling the triangular holes of h-BN shows special magnetic properties. [23][24][25][26][27][28][29] Patchworks formed by such reknitting of holes [ 30 ] can result in quantum confi nement effects.…”