通过发光光谱区分层状材料中的不同堆叠方式
Distinguishing different stackings in layered materials via luminescence spectroscopy
AI总结：
本文结合阴极荧光实验与第一性原理计算，通过完整积分激子和声子动量，解释了六方与菱方氮化硼紫外发光峰的差异，实现层状材料堆叠方式的区分。
摘要：
尽管层状氮化硼晶体结构简单，但其声子辅助发光峰却呈现出令人惊讶的复杂多样性。我们提出了一项结合实验与理论的研究，针对六方和菱方体块体氮化硼晶体中的紫外光发射。高质量样品的发射光谱通过阴极荧光光谱测量，显示出两种多型体之间的特征差异。这些差异通过一种完全第一性原理的计算技术加以解释，该技术考虑了来自“间接”有限动量激子通过耦合有限动量声子的辐射发射。我们表明，一旦对激子和声子的所有相关动量进行完整积分，峰位置、峰数量以及相对强度的差异便可以得到定性和定量的解释。
英文摘要：
Despite its simple crystal structure, layered boron nitride features a surprisingly complex variety of phonon-assisted luminescence peaks. We present a combined experimental and theoretical study on ultraviolet-light emission in hexagonal and rhombohedral bulk boron nitride crystals. Emission spectra of high-quality samples are measured via cathodoluminescence spectroscopy, displaying characteristic differences between the two polytypes. These differences are explained using a fully first-principles computational technique that takes into account radiative emission from ``indirect'', finite-momentum, excitons via coupling to finite-momentum phonons. We show that the differences in peak positions, number of peaks and relative intensities can be qualitatively and quantitatively explained, once a full integration over all relevant momenta of excitons and phonons is performed.
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