Boll Mads K, Radko Ilya P, Huck Alexander, Andersen Ulrik L
Opt Express. 2020 Mar 2;28(5):7475-7487. doi: 10.1364/OE.386629.
Quantum emitters in hexagonal boron nitride (hBN) have attracted significant interest due to their bright and narrowband photon emission even at room temperature. The wide-bandgap two-dimensional material incorporates crystal defects of yet-unknown configuration, introducing discrete energy levels with radiative transition frequencies in the visible spectral range. The commonly observed high brightness together with the moderate fluorescence lifetime indicates a high quantum efficiency, but the exact dynamics and the underlying energy level structure remain elusive. In this study we present a systematic and detailed analysis of the photon statistics recorded for several individual emitters. We extract the individual decay rates by modeling the second-order correlation functions using a set of rate equations based on an energy level scheme involving long-lived states. Our analysis clearly indicates excitation-power-dependent non-radiative couplings to at least two metastable levels and confirms a near unity quantum efficiency.
六方氮化硼（hBN）中的量子发射器因其即使在室温下也能发出明亮且窄带的光子而备受关注。这种宽带隙二维材料包含构型未知的晶体缺陷，从而引入了在可见光谱范围内具有辐射跃迁频率的离散能级。普遍观察到的高亮度以及适中的荧光寿命表明其具有高量子效率，但确切的动力学过程和潜在的能级结构仍不清楚。在本研究中，我们对几个单个发射器记录的光子统计进行了系统而详细的分析。我们通过基于包含长寿命态的能级方案，使用一组速率方程对二阶关联函数进行建模，从而提取出各个衰减率。我们的分析清楚地表明，至少与两个亚稳态存在与激发功率相关的非辐射耦合，并证实了接近单位的量子效率。
