Resonance-Enhanced Excitation of Interlayer Vibrations in Atomically Thin Black Phosphorus
Resonance-Enhanced Excitation of Interlayer Vibrations in Atomically Thin Black Phosphorus
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DOI：
10.1021/acs.nanolett.1c00917
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发表时间：
2021-05-28
期刊：
影响因子：
10.8
通讯作者：
Tisdale, William A.
中科院分区：
文献类型：
--
作者：
Mao, Nannan;Lin, Yuxuan;Tisdale, William A.
层间耦合的强度严重影响了诸如黑磷（BP）的2D材料的物理性质，其中电子结构敏感地取决于层厚度。刚性层振动直接反映了二维货车德瓦耳斯固体中的层间耦合强度，但由于样品的不稳定性和原子级薄的元素晶体中小的拉曼散射截面，使得这些特征频率的测量变得困难。在这里，我们克服了这些挑战，在BP下进行共振增强的低频拉曼散射氩气保护的环境。原子薄BP层间呼吸模式是以前无法观察到的常规（非共振）激发下，但变得强烈增强时，激发能量匹配的子带电子跃迁的几层BP，双层厚度。在BP中测得的面外层间力常数为10.1 × 10（19）N/m（3），与石墨烯相当。层间耦合强度的准确表征为今后探索BP扭曲结构和异质结构奠定了基础。
The strength of interlayer coupling critically affects the physical properties of 2D materials such as black phosphorus (BP), where the electronic structure depends sensitively on layer thickness. Rigid-layer vibrations reflect directly the interlayer coupling strength in 2D van der Waals solids, but measurement of these characteristic frequencies is made difficult by sample instability and small Raman scattering cross sections in atomically thin elemental crystals. Here, we overcome these challenges in BP by performing resonance-enhanced low-frequency Raman scattering under an argon-protective environment. Interlayer breathing modes for atomically thin BP were previously unobservable under conventional (nonresonant) excitation but became strongly enhanced when the excitation energy matched the subband electronic transitions of few-layer BP, down to bilayer thicknesses. The measured out-of-plane interlayer force constant was found to be 10.1 x 10(19 )N/m(3) in BP, which is comparable to graphene. Accurate characterization of the interlayer coupling strength lays the foundation for future exploration of BP twisted structures and heterostructures.