Low-Thermal-Budget Activation of Quantum Emitters in hBN Flakes

Single photon emitters (SPEs), including those in hexagonal boron nitride (hBN), are key components of quantum technology. Although various techniques can activate SPEs in hBN, they often yield substantial fluorescence backgrounds and broad emission line widths, resulting in spectral congestion and potentially hindering quantitative applications. In this study, we demonstrate a systematic oxygen-rich annealing strategy at moderate temperatures that effectively activates quantum emitters in hBN flakes. This approach can activate emitters exhibiting sharp zero-phonon lines (ZPLs), high signal-to-noise ratios (SNRs), and large Debye–Waller (DW) factors, while remaining nondestructive to the hBN surface. Furthermore, statistical analysis of the emitters’ ZPLs offers clues to their possible origins, while spectral curve fitting provides additional insights supporting the autocorrelation measurements. Our study introduces an emitter activation method that could fulfill the requirements for practical or quantitative applications: for example, device fabrication and thermal measurement.