  Colour centres in hexagonal boron nitride (hBN) have emerged as intriguing
contenders for integrated quantum photonics. In this work, we present detailed
photophysical analysis of hBN single emitters emitting at the blue spectral
range. The emitters are fabricated by different electron beam irradiation and
annealing conditions and exhibit narrow-band luminescence centred at 436 nm.
Photon statistics as well as rigorous photodynamics analysis unveils potential
level structure of the emitters, which suggests lack of a metastable state,
supported by a theoretical analysis. The potential defect can have an
electronic structure with fully occupied defect state in the lower half of the
hBN band gap and empty defect state in the upper half of the band gap. Overall,
our results are important to understand the photophysical properties of the
emerging family of blue quantum emitters in hBN as potential sources for
scalable quantum photonic applications.
