Researchers at the University of Vienna and Uppsala University found that electron irradiation of hexagonal boron nitride creates circular pores in ultra-high vacuum, revising earlier assumptions about defect formation in the two-dimensional material.
According to a study published in Nature Communications, exposing hexagonal boron nitride to electron beams under ultra-high vacuum produces circular pores. However, introducing even small amounts of oxygen into the atmosphere during testing drives those pores to expand into triangular shapes with nitrogen-terminated edges.
For nearly two decades, researchers using transmission electron microscopes attributed triangular pores to the lower displacement threshold energy of boron atoms, with or without inelastic scattering events. Those previous experiments took place under standard high-vacuum conditions, generally assuming that chemical reactions caused by residual gases had negligible effects.
The team confirmed that the shape mechanism holds across samples from different manufacturers and across distinct material types. The outcome remained identical across different electron energies, appearing under both focused scanning beams and defocused stationary beams.
The results explain the chemical origin of triangular pores and establish a deterministic approach to creating atomically defined pores in hexagonal boron nitride.
The peer-reviewed research was received on 15 December 2025, accepted on 30 July 2026, and published on 11 August 2026. The Austrian Science Fund funded the study in part under project codes 10.55776/COE5 and 10.55776/P36264, with the authors declaring no competing interests.
