Atomically Precise Control of Carbon Insertion into hBN Monolayer Point Vacancies using a Focused Electron Beam Guide

Abstract

Precise controlled filling of point vacancies in hBN with carbon atoms is demonstrated using a focused electron beam method, which guides mobile C atoms into the desired defect site. Optimization of the technique enables the insertion of a single C atom into a selected monovacancy, and preferential defect filling with sub-2 nm accuracy. Increasing the C insertion process leads to thicker 3D C nanodots seeded at the hBN point vacancy site. Other light elements are also observed to bind to hBN vacancies, including O, opening up a wide range of complex defect structures that include B, C, N, and O atoms. The ability to selectively fill point vacancies in hBN with C atoms provides a pathway for creating non-hydrogenated covalently bonded C molecules embedded in the insulating hBN.

Quantum sensor in a single layer van der Waals material

“…In our measurements, a nearly defect free hBN layer is suspended on a metallic grid. As the electron beam scans through the sample defects, more likely boron vacancies are created 32 . Prior work showed that electron beam irradiation of monolayer hBN causes ejection of B and N atoms around point defects.…”

“…A range of different small point defects result, and in some cases the VB2 defect is produced. We note also that high positioning accuracy may be achieved in defect fabrication in STEM by using focused electron beam pulses at specific points instead of scanning the surface 32 . The VB2 configuration may also be realized in bulk hBN by either electron or neutron irradiation and subsequent annealing at 1000 K. For further details on fabrication, see Supplementary Note 2 .…”

Towards automating structural discovery in scanning transmission electron microscopy *

“…Structural discovery is not a universal concept, as it can be driven by different considerations and often reward functions are defined a priori. For example, in atomic manipulation experiments [19][20][21][39][40][41][42][43][44][45][46], we seek to find regions of clean graphene, away from contaminations and free of defects. Reversely, in experiments focusing on exploring the chemistry of graphene, we want to find regions with high defect density.…”

Ultraviolet Quantum Emitters in Hexagonal Boron Nitride from Carbon Clusters

“…Among those, we identify a six-carbon ring defect, in which the carbon atoms substitute one BN honeycomb of hBN lattice, as one stable defect configuration. It is noteworthy that this defect has already been unambiguously identified via annular dark field scanning transmission electron microscopy (ADF-STEM) 31 , 32 and can be intentionally introduced into the lattice with atomic precision by the focused electron beam. 32 We show that this color center emits light due to strong electron coupling with E -phonon modes, caused by the product Jahn–Teller effect.…”

“…It is noteworthy that this defect has already been unambiguously identified via annular dark field scanning transmission electron microscopy (ADF-STEM) 31 , 32 and can be intentionally introduced into the lattice with atomic precision by the focused electron beam. 32 We show that this color center emits light due to strong electron coupling with E -phonon modes, caused by the product Jahn–Teller effect. More specifically, the respective symmetry lowering is found to activate a forbidden transition through an intensity borrowing mechanism from a higher-lying bright state.…”