Defect conversion in h-BN using electron beam irradiation for blue emission

Hexagonal boron nitride (h-BN) is a layered van der Waals material with a bandgap of 6 eV. Thanks to its ultra-wide bandgap, h-BN can host a series of solid-state color centers, covering a range of wavelengths from UV to the visible region. h-BN emitters have attracted particular attention, not only for their high stability and strong luminescence at room temperature, but also due to their anti-bunching behavior, a characteristic of quantum emitters. In this work, we report the controlled generation of 437 nm quantum emitters (referred to as “blue emitters”) in h-BN <i>via</i> electron beam irradiation. We demonstrate that irradiation of h-BN using 3–10 keV electron beams in a scanning electron microscope (SEM) produces the blue emitters in a spatially precise manner, as measured using photoluminescence (PL). We establish the correlation between the incident electron dose and PL intensity, indicating that the negative charge trapped in h-BN facilitates the 437 nm emission.<br/>To explore the structural origin of the h-BN blue emitters, we introduce point defects to h-BN using a helium ion microscope (HIM) before electron beam irradiation and show that the blue emitter PL intensity increased in the defect-engineered area. Furthermore, using a scanning transmission electron microscope (STEM) coupled with cathodoluminescence (CL), we observe the real-time activation and saturation of the blue emitter in pristine h-BN. The resulting emission is stable for &gt;1000 s, making it a promising candidate for photonic device integration. We achieved controlled production of electron beam-induced blue emitters in h-BN by tuning the electron dose and native defect density, which advances our understanding of their structural origin as the conversion of native defects in the h-BN lattice. These h-BN blue emitters with enhanced spectral stability can serve as a building block for future photonic devices.