Hexagonal boron nitride (hBN) is a wide, indirect bandgap semiconductor with
significant potential for optoelectronic applications in the ultraviolet and mid-
infrared spectral ranges. More importantly, it is a promising platform for single-
photon emission (quantum light), making it a candidate for optical quantum qubits
operating at room temperature. The performance of such optoelectronic devices is
largely governed by the dynamics of photogenerated carriers. In this work, we
investigate the dynamics of photoexcited free carriers in exfoliated, 10B-enriched
(99%), hBN at room temperature using ultrafast spectroscopy. We identify three
distinct recombination mechanisms: a slow, excitation-independent process
attributed to Shockley−Read−Hall (SRH) recombination associated with lattice
defects and impurities; a bimolecular recombination mechanism that dominates at
moderate excitation densities; and Auger recombination, which becomes
significant at higher excitation densities. Notably, the Auger recombination rate
observed in hBN is considerably higher than in other nitride-based semiconductors.
This elevated rate is sufficient to reduce the internal quantum efficiency of hBN-
based devices under high charge carrier densities. The large Auger coefficient may
be attributed to charge localization induced by defects and impurities, as well as
strain-related built-in polarization fields. Finally, I will highlight how our work
informs the development of next-generation electronic and photonic devices,
paving the way for advancements in high-performance, energy-efficient
technologies.