Site-Selective Creation of Blue Emitters in Hexagonal Boron Nitride

Hexagonal boron nitride (hBN) has been of great interest due to its ability to host several bright quantum emitters at room temperature. However, the identification of the observed emitters remains challenging due to spectral variability, as well as the lack of atomic defect structure information. In this work, we demonstrate the site-selective creation of blue emitters in exfoliated hBN flakes with high-energy ion irradiation. With the correlation analysis of cryogenic and temperature-dependent photoluminescence (PL) spectroscopy, we observe two zero phonon lines (ZPLs) at ∼432.8 and 454.3 nm. Photoluminescence excitation (PLE) measurements further confirm the emission origins of the two prominent lines. Scanning transmission electron microscopy (STEM) reveals that the dominant defect structures present in ion-irradiated samples are vacancy-type (V_x) and adatom(intercalant)-type (A_x). Together with first-principles GW-BSE (Bethe-Salpeter equation) calculations, we deduce that the observed blue emissions are likely related to boron intercalants (B_int). Our results not only discover a group of blue emissions in hBN but also provide insights into the physical origin of the emissions with local atomic structures in hBN.