Observation of Boron Vacancy Concentration in Hexagonal Boron Nitride at Nanometer Scale.

Kikkawa, Jun; Shinei, Chikara; Chen, Jun; Masuyama, Yuta; Yamazaki, Yuichi; Mizoguchi, Teruyasu; Kimoto, Koji; Taniguchi, Takashi et al. · Nano Lett · 2025

basic_science · Level V

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Abstract

Negatively charged boron vacancy (V<sub>B</sub><sup>-</sup>) ensembles in hexagonal boron nitride (h-BN) have attracted considerable attention as a promising platform for quantum sensing. Current challenges include the experimental validation of the spatial distribution and electronic states of optically active V<sub>B</sub><sup>-</sup> and optically inactive neutral boron vacancy (V<sub>B</sub><sup>0</sup>) defects. To address these issues, we employ electron energy loss spectroscopy (EELS) combined with scanning transmission electron microscopy (STEM) using monochromated 30-keV electrons, effectively reducing background interference. This approach unveils distinct spectral peaks at 2.5 and 1.9 eV, corresponding to V<sub>B</sub><sup>-</sup> and V<sub>B</sub><sup>0</sup> defects, respectively. Furthermore, we achieve nanometer-scale concentration mapping for V<sub>B</sub><sup>-</sup> and V<sub>B</sub><sup>0</sup> defects, advancing insights into spin defect configurations crucial for optimizing quantum sensor performance.