Auger recombination kinetics of the free carriers in hexagonal boron nitride

Hexagonal boron nitride (hBN) is a broad-bandgap strongly luminescent semiconductor many orders of magnitude higher than diamond, which holds great promise for optoelectronic devices over a wide frequency range spanning from UV to mid-IR. Auger recombination, is a nonradiative mechanism, is one of the three mechanisms that determine the kinetics of the photoexcited carriers and strongly contributes to losses in efficiency. Here we report on the dynamics of photogenerated free carriers in exfoliated ¹⁰B-enriched (99%) hBN at room temperature. Auger and defect-assisted recombination mechanisms were identified experimentally by utilizing ultrafast transient reflection spectroscopy. Recombination at high carrier density occurs via an Auger process with a characteristic rate constant of with a strong dependence on the excitation fluence. A slower recombination mechanism independent of the excitation fluence at a rate of × was assigned to defects.