Hexagonal boron nitride (h-BN) crystal powders were characterized for structural and optical properties. Deep UV photoluminescence (PL) spectroscopy was employed for the optical characterization. We studied the effect of annealing on the PL emissions from the h-BN crystal powders. We observed sharp atomic-like PL emission lines in the UV spectral region at 4.10 and 4.12 eV along with their longitudinal optical phonon replicas from the samples annealed in ambient air around 700 ^oC for 1 hour which were not present in the unannealed samples. Our study suggests that the point defects related to the atomic-like emissions are generated during the annealing process of the h-BN. Based on the theoretical calculation results, the atomic-like emissions in the UV region have been assigned to a carbon dimer defect. The annealed h-BN powder samples also exhibited pronounced phonon assisted band-edge emission peaks at 5.78 and 5.89 eV, and enhanced emission intensity of the major peak at 5.49 eV in the low temperature (8 K) PL spectrum.

表征六方氮化硼（h-BN）晶体粉末的结构和光学性质。深紫外光致发光（PL）光谱用于光学表征。我们研究了退火对h-BN晶体粉末PL排放的影响。我们在4.10和4.12 eV的UV光谱区域观察到了尖锐的原子状PL发射线，以及在约700 ^o的环境空气中退火的样品中的纵向光学声子副本保持1小时，这在未退火的样品中不存在。我们的研究表明，与原子状发射有关的点缺陷是在h-BN的退火过程中产生的。根据理论计算结果，将UV区的类原子发射归因于碳二聚体缺陷。退火的h-BN粉末样品在低温（8 K）PL光谱中还显示出明显的声子辅助的带边发射峰，其在5.78和5.89 eV处，并且主峰的发射强度在5.49 eV处增强。