Abstract

Understanding electron irradiation effects is vital not only for reliable characterization of materials using transmission electron microscopy, but increasingly also for the controlled manipulation of two-dimensional materials. Knock-on displacements due to elastic electron backscattering are theoretically straightforward to model, and appear to correctly describe damage in pristine graphene. For semiconducting MoS2, however, a combination of elastic and inelastic effects appears to be needed to explain experiments. For insulating hexagonal boron nitride (hBN), much less is currently known. The paper measures displacement cross sections of suspended monolayer hBN using aberration-corrected scanning transmission electron microscopy in near ultra-high vacuum at primary beam energies between 50 and 90 keV, shows that single vacancies can be created by electron irradiation, and develops a theoretical description of ionization-assisted displacement threshold reduction using charge-constrained density functional theory molecular dynamics.

Abstract

Understanding electron irradiation effects is vital not only for reliable characterization of materials using transmission electron microscopy, but increasingly also for the controlled manipulation of two-dimensional materials. Knock-on displacements due to elastic electron backscattering are theoretically straightforward to model, and appear to correctly describe damage in pristine graphene. For semiconducting MoS2, however, a combination of elastic and inelastic effects appears to be needed to explain experiments. For insulating hexagonal boron nitride (hBN), much less is currently known. The paper measures displacement cross sections of suspended monolayer hBN using aberration-corrected scanning transmission electron microscopy in near ultra-high vacuum at primary beam energies between 50 and 90 keV, shows that single vacancies can be created by electron irradiation, and develops a theoretical description of ionization-assisted displacement threshold reduction using charge-constrained density functional theory molecular dynamics.

Abstract

Understanding electron irradiation effects is vital not only for reliable characterization of materials using transmission electron microscopy, but increasingly also for the controlled manipulation of two-dimensional materials. Knock-on displacements due to elastic electron backscattering are theoretically straightforward to model, and appear to correctly describe damage in pristine graphene. For semiconducting MoS2, however, a combination of elastic and inelastic effects appears to be needed to explain experiments. For insulating hexagonal boron nitride (hBN), much less is currently known. The paper measures displacement cross sections of suspended monolayer hBN using aberration-corrected scanning transmission electron microscopy in near ultra-high vacuum at primary beam energies between 50 and 90 keV, shows that single vacancies can be created by electron irradiation, and develops a theoretical description of ionization-assisted displacement threshold reduction using charge-constrained density functional theory molecular dynamics.

Abstract

Understanding electron irradiation effects is vital not only for reliable characterization of materials using transmission electron microscopy, but increasingly also for the controlled manipulation of two-dimensional materials. Knock-on displacements due to elastic electron backscattering are theoretically straightforward to model, and appear to correctly describe damage in pristine graphene. For semiconducting MoS2, however, a combination of elastic and inelastic effects appears to be needed to explain experiments. For insulating hexagonal boron nitride (hBN), much less is currently known. The paper measures displacement cross sections of suspended monolayer hBN using aberration-corrected scanning transmission electron microscopy in near ultra-high vacuum at primary beam energies between 50 and 90 keV, shows that single vacancies can be created by electron irradiation, and develops a theoretical description of ionization-assisted displacement threshold reduction using charge-constrained density functional theory molecular dynamics.