结合六方氮化硼中发光中心的实验与极化子模型及从头算方法以探究其微观起源
Combining experiments on luminescent centres in hexagonal boron nitride with the polaron model and ab initio methods towards the identification of their microscopic origin
AI总结：
本研究结合ab initio计算与非微扰开放量子系统理论，分析了26种缺陷跃迁，将hBN中发光中心的微观起源缩小至三种碳基缺陷，并验证了基于极化子的理论方法与PLE实验高度一致。
摘要：
二维材料六方氮化硼（hBN）包含发射能量为2 eV且表现出明显声子侧带的发光中心。我们通过结合ab initio计算与非微扰开放量子系统理论，研究了26种缺陷跃迁的发射和吸收特性，从而探究这些发光中心的微观起源。通过将计算出的线形与实验进行比较，我们将微观起源缩小至三种碳基缺陷：$\mathrm{C_2C_B}$、$\mathrm{C_2C_N}$和$\mathrm{V_NC_B}$。所开发的理论方法使我们能够计算所谓的光致发光激发（PLE）图，该图与我们的实验表现出极好的一致性。后者解析了高阶声子跃迁，从而证实了光学跃迁的电子振动结构以及具有170 meV声子能量的声子辅助激发机制。我们认为，所提出的实验和基于极化子的方法准确描述了hBN中的发光中心，并将有助于确定其微观起源。
英文摘要：
The two-dimensional material hexagonal boron nitride (hBN) hosts luminescent centres with emission energies of 2 eV which exhibit pronounced phonon sidebands. We investigate the microscopic origin of these luminescent centres by combining ab initio calculations with non-perturbative open quantum system theory to study the emission and absorption properties of 26 defect transitions. Comparing the calculated line shapes with experiments we narrow down the microscopic origin to three carbon-based defects: $\mathrm{C_2C_B}$, $\mathrm{C_2C_N}$, and $\mathrm{V_NC_B}$. The theoretical method developed enables us to calculate so-called photoluminescence excitation (PLE) maps, which show excellent agreement with our experiments. The latter resolves higher-order phonon transitions, thereby confirming both the vibronic structure of the optical transition and the phonon-assisted excitation mechanism with a phonon energy 170 meV. We believe that the presented experiments and polaron-based method accurately describe luminescent centres in hBN and will help to identify their microscopic origin.
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